Title of Invention	PROCESS OF AND DEVICE FOR MACHINING OF BALL TRACKS AND GUIDING WEBS OF BALL HUBS SIMULTANEOUSLY
Abstract	A process machining inner joint parts 11 of constant velocity universal ball joints, which inner joint parts 11 comprise a longitudinal axis A and at least one guiding face by means of which the inner joint part 11 is continiously angularly movably guided in a ball cage, and which comprise a plurality of ball tracks 12 which are distributed around the circumference of the guiding face and which divide the guiding face into a corresponding plurality of guiding webs 13 and in which torque transmitting balls can be held so as to be longitudinally displaceable, wherein one ball track 12 and at least one guiding web 13 are machined simultaneously.

Title of Invention

PROCESS OF AND DEVICE FOR MACHINING OF BALL TRACKS AND GUIDING WEBS OF BALL HUBS SIMULTANEOUSLY

Abstract

A process machining inner joint parts 11 of constant velocity universal ball joints, which inner joint parts 11 comprise a longitudinal axis A and at least one guiding face by means of which the inner joint part 11 is continiously angularly movably guided in a ball cage, and which comprise a plurality of ball tracks 12 which are distributed around the circumference of the guiding face and which divide the guiding face into a corresponding plurality of guiding webs 13 and in which torque transmitting balls can be held so as to be longitudinally displaceable, wherein one ball track 12 and at least one guiding web 13 are machined simultaneously.

Full Text	1 GKN Driveline International GmbH 29th November 2004 Hauptstrasse 130 Ne/bec (20040424) 53797 Lohmar Q04017WO00 Process of and device for machining ball hubs Description The invention relates to processes of and devices for machin- ing the inner joint parts of constant velocity universal ball joints, which inner joint parts are also referred to as ball hubs. Such inner joint parts have a longitudinal axis A and comprise at least one guiding face by means of which the inner joint part is continuously angularly movably guided relative to the ball cage. On said guiding face there is positioned a plurality of circumferentially distributed ball tracks which divide the guiding face into a corresponding plurality of guiding webs. Torque transmitting balls of the constant veloc- ity universal ball joint can be longitudinally displaceably held in the ball tracks. As is generally known, constant ve- locity universal ball joints of this type comprise an outer joint part with first ball tracks, a ball cage holding a plu- rality of balls, as well as the inner joint part which is re- ferred to here and which has second ball tracks (not explained in greater detail below). More particularly, but not exclu- sively, the inner joint parts of the above-described type are suitable for constant velocity universal ball joints which are referred to by the applicant as AC (angular contact), UF (undercut free), DO (double offset), HAI (high angle inboard) and TBJ (twin ball joint) joints. These designations have largely developed into standard terms referring to species. 2 When producing prior art inner joint parts it is already known to subject the workpieces in a common clamping device first to machining operations on the individual ball tracks and subse- quently to machining operations on the guiding webs. When ma- chining the ball tracks, the ball hub is held in position and by means of rotating tools, the ball tracks are machined track by track in a chip-forming way. More particularly, the already hardened tracks are ground. Thereafter, the ball hub, in a ro- tatingly driven condition, is finish-turned (on outer diame- ter) and then form-ground. It is the object of the present invention to further rational- ise the process of producing ball hubs of said type and to provide devices for carrying out said process. A first solution consists in providing a process of machining the inner joint parts of constant velocity universal joints, which inner joint parts have a longitudinal axis A and com- prise at least one guiding face by means of which the inner joint part is continuously angularly movably guided in a the ball cage, and which comprises a plurality of ball tracks which are distributed around the circumference of the guiding face, which divide the guiding face into a corresponding plu- rality of guiding webs and in which the torque transmitting balls can be held so as to be longitudinally displaceable, which inner joint part is characterised in that at least one ball track and at least one guiding web are machined in a chip-forming way simultaneously. With set-up times which are as advantageous as those used so far, i.e. by using a clamping device, the inventive process is suitable for shortening the machining times and for considera- bly reducing the down-times of the individual tools. Said chip-forming machining operation can comprise both milling 3 processes and grinding processes as well a combination of the two. With a given output the investment costs are reduced con- siderably by the inventive process. More particularly while adhering to the further embodiments mentioned below, it is possible to achieve quality improve- ments, i.e. that in the case of uneven numbers of ball tracks and guiding webs, one ball track and one radially opposed gui- ding web are machined simultaneously and that in the case of even numbers of ball tracks and guiding webs, one ball track and one guiding web adjoining the radially opposed ball track are machined simultaneously. In this way, either no transverse forces or only low transverse forces are applied to the clamping device for the workpiece, so that the tracks and guiding webs can be produced with a higher degree of preci- sion. Because the rotating tools used are form tools, tracks of any cross-section can be produced. Production can be increased further in that two ball tracks and two faces are machined simultaneously or that at least two - more particularly two ball tracks positioned in planes ex- tending parallel relative to one another - are simultaneously machined in the longitudinal direction synchronously and, with one or two guiding webs being machined at least par- tially simultaneously thereto. According to a second solution which substantially has the same advantages as the above-described solution, there is pro- posed a process of machining inner joint parts of constant velocity universal ball joints , which inner joint parts have a longitudinal axis and comprise at least one guiding face by means of which the inner joint part is continuously angularly movably guided in a the ball cage, and which comprises a plu- rality of ball tracks which are distributed around the circum- 4 ference of the guiding face, which divide the guiding face in- to a corresponding plurality of guiding webs and in which the torque transmitting balls can be held so as to be longitu- dinally displaceable, wherein at least two ball tracks are ma- chined simultaneously in a chip-forming way in the longitudi- nal direction. Finally, according to a third solution which also has the same advantages as described above, there is proposed a process of machining inner joint parts of constant velocity universal ball joints , which inner joint parts have a longitudinal axis and comprise at least one guiding face by means of which the inner joint part is continuously angularly movably guided in a ball cage, and which comprises a plurality of ball tracks which are distributed around the circumference of the guiding face, which divide the guiding face into a corresponding plu- rality of guiding webs and in which the torque transmitting balls can be held so as to be longitudinally displaceable, wherein at least two guiding tracks are machined simultane- ously in a chip-forming way in the longitudinal direction. With the processes mentioned here it is also possible to achieve an improvement in quality in that with uneven numbers of ball tracks and guiding webs, a first ball track or web face and the second ball track or guiding web adjoining the radially opposed partial face or ball track are machined si- multaneously and that with even numbers of ball tracks and guiding webs, two radially opposed ball tracks or guiding webs are machined simultaneously. In this case, too, the forces acting on the workpiece can be largely balanced, so that the transverse forces and bearing load at the clamping device are reduced, with the production accuracy being increased. 5 According to a preferred process which will be explained in more detail with reference to the drawings, the ball tracks are machined by rotating tools whose axes of rotation inter- sect the longitudinal axis of the inner joint part perpendicu- larly and whose centre is guided in radial planes which, rela- tive to the inner joint part, extend through the longitudinal axis. Alternatively, it is possible for the ball tracks to be ma- chined by rotating tools whose axes of rotation are aligned substantially radially relative to the longitudinal axis of the inner joint part, wherein the axis of rotation, rela- tively, is guided in radial planes extending through the lon- gitudinal axis of the inner joint part. With reference to the production of the guiding webs it is proposed that the guiding webs are machined by rotating tools whose axis of rotation intersects the longitudinal axis of the inner joint part perpendicularly and whose centre, relative to the inner joint part, is guided in radial planes which extend through the longitudinal axis of the inner joint part because in view of the hollow shape of the tool face, only disc tools can be used and not finger tools. In order to make it possible for several guiding webs to be machined by one tool without having to rotate the clamped-in workpiece, it is proposed ac- cording to a further supplementary process that the guiding webs are machined by rotating tools, whose centre, relative to the inner joint part, additionally carries out pivot movements around its longitudinal axis. In accordance with the initially mentioned objective, the in- vention furthermore, according to a first proposal, comprises a device for machining inner joint parts of constant velocity universal ball joints , which inner joint parts have a longi- 6 tudinal axis and comprise at least one guiding face by means of which the inner joint part is continuously angularly mova- bly guided in a ball cage, and which comprises a plurality of ball tracks which are distributed around the circumference of the guiding face, which divide the guiding face into a corre- sponding plurality of guiding webs and in which the torque transmitting balls can be held so as to be longitudinally dis- placeable, wherein said device comprises a clamping device for the inner joint part and at least two rotating tools for si- multaneously machining at least one ball track and at least one guiding web in the longitudinal direction. According to a second solution variant which substantially leads to the same results, the invention comprises a device of the above-mentioned species which is characterised in that it comprises a clamping device for an inner joint part and at le- ast two rotating tools for simultaneously machining at least two ball tracks in the longitudinal direction. According to a further solution variant which also leads to said advantageous results, there is proposed a device which is characterised in that it comprises a clamping device for an inner joint part and at least two rotating tools for simulta- neously machining at least two guiding webs in the longitudi- nal direction. Due to the fact that it is possible to machine simultaneously a plurality of functional faces of the inventive inner joint part, productivity is improved with existing investment costs. The device can be particularly simple in design and cost- effective if the clamping device for an inner joint part com- prises feeding means at least for feeding the workpiece in the longitudinal direction of the inner joint part and if the at least two rotating tools comprise feeding means to ensure 7 feeding in the radial direction only relative to the longitu- dinal axis of the inner joint part. In addition it is proposed that the clamping device additionally comprises adjusting means for rotatingly adjusting the clamping device around the longitudinal axis of the inner joint part. More particularly, the clamping device is able to clamp in the inner joint part axially. After the rotating tools have been returned radially out- wardly, the workpiece can be rotated in its clamping device by the pitch angle of the ball tracks and the next synchronous machining operation for two functional faces can be repeated with the workpiece being fed in entirely axially and with the rotating tools being moved forward entirely radially. It is also possible to provide alternative adjusting means for ro- tatingly adjusting the rotating tools around the longitudinal axis of the inner joint part. In a preferred embodiment, the axes of rotation of all rotat- ing tools participating simultaneously in the machining opera- tion are positioned in one plane. According to a further embodiment it is proposed that the axes of rotation of the rotating tools are positioned in at least two planes extending parallel relative to one another, wherein especially the tools for dressing the guiding webs are posi- tioned in a second common plane. In this way, it is possible, with simple means, to use further tools, with the clamping de- vice remaining unchanged. It would not be possible for such further tools to be accommodated in an annular assembly in one plane with reference to the longitudinal axis of the work- piece . 8 As already indicated, the rotating tools for the ball tracks can be disc tools whose axes of rotation intersect the longi- tudinal axis of the inner joint part at a distance. However, the rotating tools for the ball tracks can also be finger tools which axes of rotation are arranged substantially ra- dially relative to the longitudinal axis of the inner joint part. As far as the rotating tools for the web faces are con- cerned, these have to be provided in the form of disc tools. Illustrations of preferred embodiments of the inventive proc- ess from which there are derived preferred embodiments of in- ventive devices are contained in the drawings and will be de- scribed below. Figure 1 shows an inventive process wherein a ball track and a web face are machined simultaneously a) in an axial view of the longitudinal axis of the inner joint part b) in a radial view of the longitudinal axis of the inner joint part in a first variant c) in a radial view of the longitudinal axis of the inner joint part in a second variant d) in a radial view of the longitudinal axis of a deviating inner joint part. Figure 2 shows an inventive process wherein two ball tracks and two web faces are machined simultaneously, in an axial view of the longitudinal axis of the inner joint part. Figure 3 shows the execution of an inventive process wherein two ball tracks are machined simultaneously, in an axial view of the longitudinal axis of the inner joint part. 9 Figure 4 shows the execution of an inventive process wherein two web faces are machined simultaneously, in an axial view of the longitudinal axis of the inner joint part. Figure 5 shows the execution of an inventive process wherein two parallel ball tracks and one web face are machined simul- taneously. Figure la shows the inventive process of machining an inner joint part 11 of a constant velocity universal joint according to a first solution. The inner joint parts of constant veloc- ity universal joints are often also referred to as ball hubs. The longitudinal axis of the inner joint part 11 has been gi- ven the reference symbol A and, below, will repeatedly be used with reference to the arrangement and to the movements of the tools used. The inner joint part 11 is shown to comprise six circumferentially distributed ball tracks 12 which, in the longitudinal direction, comprise a substantially uniform cross-section and which are shown here as approximately semi- circular round tracks. The ball tracks 12 are separated from one another by web faces 13 which are partial faces of an ima- ginary partially spherical guiding face of the inner joint part by means of which the inner joint part 11 is guided so as to be articulatable relative to a ball cage. It is common practice for said guiding face to be a disc portion of a ball. However, the guiding face can also be interrupted by a central over-turning, so that, as an imaginary guiding face, it forms two axially spaced ball discs between which there is posi- tioned a non-guiding intermediate portion. At the guiding webs 13 and at the delimiting edges of the ball tracks 12 it is possible to identify chamfers 14, 15 which are irrelevant for the inventive production process. The inner joint part 11 com- prises a through-aperture 16 which extends coaxially relative to the longitudinal axis A and comprises inner shaft teeth 17 10 which are provided for inserting a drive shaft journal. There are provided a first rotating tool 21 constituting a form tool for rotatingly machining the ball tracks 12 as well as a sec- ond rotating tool 31 constituting a rotating form tool for ma- chining the guiding webs 13, which rotating tools 21, 31, in accordance with the invention, engage the inner joint part si- multaneously. The axis of rotation of the tools 21 has been given the reference symbol R21 and the axis of rotation of the tool 31 has been given the reference symbol R31. The two axes X21 and X31 which intersect the longitudinal axis A in the same point and whose significance will be referred to in connection with the following figure each extend perpendicularly relative to the direction of the longitudinal axis A. An arch-shaped arrow P shown in dash-dotted lines indicates the possibility of adjusting the tools 21, 31 relative to the inner joint part 11, with the centre of movement being positioned on the longi- tudinal axis A. However, said possibility of movement consti- tutes one option only. Alternatively, a holding element for the inner joint part 11 can be designed so as to be rotatingly adjustable. Figures lb, lc show the process and the device according to Figure la in an angled longitudinal section through the axis A and the axes X21, X31. The inner joint part 11 is shown to com- prise an aperture 16 which extends coaxially relative to the longitudinal axis A and comprises inner teeth 17. One of the ball tracks 12 is shown to engage the rotating tool 21. One of the web faces 13 is shown to engage the rotating tool 31. The movement of the tools 21, 31 relative to the inner joint part 11 is such that the inner joint part 11 is moved entirely axi- ally on the clamping axis Z in the direction of the double ar- row Z11, whereas the rotating tools 21, 31 are each moved en- tirely in the direction of the double arrows X12, X113 along the axes X21, X31. The axes X21, X31 are positioned in a common plane 11 which extends radially relative to the clamping axis Z; ac- cording to Figure lb they coincide and according to Figure lc they are offset in parallel relative to one another. In order to change over to machining a further ball track and a further web face after a ball track 12 and a web face 13 have been fully machined simultaneously, the tools 21, 31 can be moved out of the engagement with the inner joint part 11 radially relative to the clamping axis Z, and the inner joint part 11 can be rotated around the clamping axis Z by a pitch angle of the ball tracks 12. The necessary types of movement and con- trol of the device are thus the rotation of the clamping de- vice and the displacement of the clamping device in direction Z as well as an entirely axial displacement of the axes of rotation R21, R31 along the radial axes X21, X31. Figure 1d shows a process and a device similar to those shown in Figure la for a deviating inner joint part 11 in an angled longitudinal section through the axis A and the axes X21, X31. The inner joint part 11 is axially clamped into a two-part clamping device 18. The inner joint part 11 can be seen to comprise a through-aperture 16 extending coaxially relative to the longitudinal axis A. One of the straight ball tracks 12 engages the rotating tool 21. One of the web faces 13 engages the rotating tool 31. The path of the tools 21, 13 relative to the inner joint part 11 has been indicated by dash-dotted li- nes. The actual movement, however, is such that the inner joint part 11 is moved on the clamping axis Z entirely axially in the direction of the double arrow Z11 whereas the rotational tools 21, 13 are moved entirely in the direction of the double arrows X12, X13 along the axes X21, X31, the former operation be- ing only for setting purposes and the latter operation taking place during the entire process. The axes X21, X31 are posi- tioned in a common plane extending radially relative to the clamping axis Z. In order to change over to machining a fur- 12 ther ball track and a further web face after a ball track 12 and a web face 13 have been fully machined simultaneously, the tools 21, 31 can be moved out of the engagement with the inner joint part 11 radially relative to the clamping axis Z, and the inner joint part 11 can be rotated around the clamping axis Z by a pitch angle of the ball tracks 12. The necessary types of movement and control of the device are thus the rota- tion of the clamping device 18 and the displacement of the clamping device 18 in direction Z as well as an entirely ra- dial displacement of the axes of rotation R21, R31 along the radial axes X21, X31. As can be seen in Figure la, it is advantageous if, for the purpose of balancing the forces, the two tools 21, 31 are ar- ranged largely radially opposite one another. With the even number of ball tracks 12 shown here, it is necessary to devi- ate from said ideal by half a pitch angle of the ball tracks. If the chip-forming machining process requires several succes- sive stages such as milling and grinding, further sets of pairs of tools can be arranged in planes extending parallel to the drawing plane of Figure la, so that the inner joint part 11, without having to be re-clamped and while using the en- tirely axial feeding facilities can be fed to the further set(s) of tools. These sets of tools, too, require only one axial feeding facility in the radial direction with reference to the clamping axis Z. Figure 2 shows a modified and further embodiment of the proc- ess illustrated in Figure 1, again in an axial view of the longitudinal axis A of the inner joint part 11 analogously to Figure la. Identical details have been given the same refer- ence numbers as in Figure 1, so that reference is made to the description of same. In addition to the rotating tool 21 for 13 the ball track 12, there is shown a deviating second tool 22 for a ball track 12' positioned radially opposite. Further- more, in addition to the tool 31 for the web region 13, there is illustrated a further identical tool 32 for a web 13' posi- tioned radially opposite. The axes X21, X31 form a 90° angle, so that at the inner joint part 11, during the chip-forming ma- chining operation, the forces are largely balanced with refer- ence to the clamping axis Z, i.e. in contrast to the embodi- ment according to Figure 1, no resulting forces act on the clamping axis Z. In this case, the device is preferably de- signed in such a way that the inner joint part 11 is displace- able along the clamping axis Z and, for the purpose of chang- ing between the individual machining operations, it can be ro- tated around the clamping axis, whereas the tools 21, 22, 31, 32 can only be moved in the direction of the individual axes X21, X22, X31, X32. Figure 3 shows the inventive machining process according to a third solution, again illustrating an inner joint part 11 in an axial view of the longitudinal axis A. Identical details have been given the same reference numbers as in the preceding figures, so that reference is made to the description of same. In accordance with the invention, two ball tracks 12, 12' are subjected to a chip-forming machining operation simultaneously by two rotating tools 21, 22 which correspond to those shown in Figure 2 and, in the same way, engage radially opposed ball tracks. In this case, too, an axial feeding operation takes place along the longitudinal axis A of the inner joint part 11 along the clamping axis Z and, in addition, the inner joint part 11 is rotatable around the axis Z by the track pitch an- gle (a). In contrast hereto, the axes of the rotatingly driven tools 21, 22 can move in the direction of the double arrows X12, X12' in the radial direction relative to the clamping axis Z. Their axes of movement X21, X22 are positioned in a common 14 plane, i.e. more particularly on a common straight line. In accordance with the arrow P' shown in dash-dotted lines, it is possible, in this case, too, to allow the tools 21, 22 to be adjustable relative to the inner joint part 11 around the cen- tre of movement A. Figure 4 shows an inventive machining process according to a fourth solution, again showing the inner joint part 11 in an axial view of the longitudinal axis. Identical details have been given the same reference numbers as the preceding fig- ures, so that reference is made to the description of same. In accordance with the invention, two web regions 13, 13' are ma- chined simultaneously by two rotating tools 31', 32 which cor- respond to those shown in Figure 2 and which, in the same way, engage radially opposed ball tracks. In this case, too, the longitudinal axis A of the inner joint part is fed forward along the clamping axis Z, and, in addition, the inner joint part is rotatable around the axis Z by the track pitch angle (a). On the other hand, the rotatingly driven tools 31', 32 can move their axes only in the direction of the double arrows X13, X13' in the radial direction relative to the clamping axis Z. Their axes of movement X32', X32 are positioned in a common plane, i.e. more particularly on a common straight line. In accordance with the dash-dotted arrow P", this case, too, al- lows the tools 31', 32 to be adjustable relative to the inner joint part 11 around the centre of movement A. Figure 5 shows a further embodiment of an inventive process, wherein the inner joint part 11 comprises ball tracks 12]., 122 which extend in pairs arranged in parallel relative to one an- other and which form first wider web regions 131 positioned be- tween two pairs and second narrower web regions 132 positioned between the two tracks 121, 122 of a pair. In this case, the tracks 121, 122 of a pair are machined by two rotating tools 23, 15 24 which comprise a common axis of rotation R23 and are rotat- ingly drivably held in a common holding device 25. The holding device 25 and thus the tools 23, 24 move radially relative to the longitudinal axis A of the inner joint part and to the clamping axis Z in the direction of the radial ray X23. The web regions 131, 132 are each machined by a rotating tool 33 which comprises an axis of rotation R33 and is rotatingly drivably received in a holding device 34. The holding device 34 and thus also the tool 33 again move radially relative to the lon- gitudinal axis A of the inner joint part 11 and thus to the clamping axis in the direction of the radial ray X33. In this case, too, the axes R32, R33 are preferably positioned in a com- mon plane. A dash-dotted arrow P"' indicates that the holding device 34 is additionally adjustable relative to the holding device 25 so that the holding device 34 can be adjusted from machining the web region 131 (as illustrated) to machining the web region 132 around the centre of movement A without there being a need to rotate the workpiece around the clamping axis. Only after the operation of machining two web regions 131, 132, which takes place at least partially simultaneously with the machining of the tracks 121, 122, has been completed, is the workpiece 11 rotated around its clamping axis by the pitch an- gle between the pairs of tracks, i.e. in this case by 90°. The holding device 34 is pivoted back into its starting position. Alternatively, with the workpiece 11 being held in a fixed po- sition, it is possible for both holding devices 25, 34 to be adjusted jointly relative to the fixed workpiece 11 around the centre of movement A. Modifications of the above-described process are possible, for example by additionally providing two tools for simultaneously machining two web regions, but which two tools have to com- prise different axes of rotation. 16 GKN Driveline International GmbH 29th November 2004 Hauptstrasse 130 Ne/bec (20040424) 53797 Lohmar Q04017WO00 Process of and device for machining ball hubs List of reference numbers 11 inner joint part 12 ball track 13 guiding web/web face 14 chamfer 15 chamber 16 through-aperture 17 teeth 18 clamping device 19 - 20 - 21 tool 22 tool 23 tool 24 tool 25 tool 31 tool 32 tool 33 tool 34 tool A longitudinal axis Z clamping axis R axis of rotation X radial axis 17 GKN Driveline International GmbH 2 9th November 2004 Hauptstrasse 130 Ne/bec (20040424) 53797 Lohmar Q04017WO00 Process of and device for machining ball hubs Claims 1. A process of machining inner joint parts (11) of con- stant velocity universal ball joints, which inner joint parts (11) comprise a longitudinal axis (A) and at least one guiding face by means of which the inner joint part (11) is orbitally angularly movably guided in a ball cage, and which comprise a plurality of ball tracks (12) which are distributed around the circumference of the guiding face and which ball tracks divide the guiding face into a corresponding plurality of guiding webs (13) and in which ball tracks torque transmitting balls can be held so as to be longitudinally displaceable, characterised in that one ball track (12) and at least one guiding web (13) are machined simultaneously. 2. A process according to claim 1, characterised in that in the case of uneven numbers of ball tracks (12) and guiding webs (13), one ball track (12) and one ra- dially opposed guiding web (13) each are machined simul- taneously. 18 3. A process according to claim 1, characterised in that in the case of even numbers of ball tracks (12) and guiding webs (13), one ball track (12) and one guiding web (13) adjoining the radially opposed ball track each are machined simultaneously. 4. A process according to any one of claims 1 to 3, characterised in that two ball tracks (12) and two guiding webs (13) each are machined simultaneously. 5. A process according to any one of claims 1 to 3, characterised in that two ball tracks (12) - more particularly two ball tracks positioned in planes extending parallel relative to one another - are simultaneously machined in the lon- gitudinal direction synchronously and at least one guid- ing web (13) is machined at least partially simultane- ously therewith. 6. A process according to claim 5, characterised in that two ball tracks positioned in planes extending par- allel relative to one another are machined by jointly driven tools (23, 24) . 19 7. A process of machining inner joint parts (11) of con- stant velocity universal ball joints, which inner joint parts (11) comprise a longitudinal axis (A) and are pro- vided with at least one guiding face by means of which the inner joint part (11) is guided orbitally angularly movably guided in a ball cage and which comprise a plu- rality of ball tracks (12) which are distributed around the circumference of the guiding face, which ball tracks divide the guiding face into a corresponding number of guiding webs (13) and in which ball tracks torque trans- mitting balls are held so as to be longitudinally dis- placeable, characterised in that at least two ball tracks (12) are machined simulta- neously in the longitudinal direction. 8. A process of machining inner joint parts (11) of con- stant velocity universal ball joints, which inner joint parts (11) comprise a longitudinal axis (A) and are pro- vided with at least one guiding face by means of which the inner joint part (11) is guided orbitally angularly movably in a ball cage and which comprise a plurality of ball tracks (12) which are distributed around the cir- cumference of the guiding face, which ball tracks divide the guiding face into a corresponding number of guiding webs (13) and in which ball tracks torque transmitting balls are held so as to be longitudinally displaceable, characterised in 20 that at least two guiding webs (13, 13') are machined simultaneously in the longitudinal direction. 9. A process according to any one of claims 7 or 8, characterised in that, in the case of uneven numbers of ball tracks (12) and guiding webs (13), a first ball track (12) or web face (13) and the second ball track (12') or guiding web (13') adjoining the radially opposed web face or ball track each are machined simultaneously. 10. A process according to any one of claims 7 or 8, characterised in that, in the case of even numbers of ball tracks (12) and guiding webs (13), two radially opposed ball tracks (12, 12') or guiding webs (13, 13') each are machined simultaneously. 11. A process according to any one of claims 1 to 10, characterised in that the ball tracks (12) are machined by rotating tools (21,22,23,24) whose axes of rotation (R) perpendicularly cross the longitudinal axis (A) of the inner joint part (11) and whose centre is guided in radial planes (X) which, relative to the inner joint part (11), extend through the longitudinal axis (A). 21 12. A process according to any one of claims 1 to 10, characterised in that the ball tracks (12) are machined by rotating tools whose axis of rotation extends substantially radially relative to the longitudinal axis (A) of the inner joint part (11), wherein the axis of rotation, relative to the inner joint part (11) , is guided in radial planes ex- tending through the longitudinal axis (A) of the inner joint part (11). (No Figure). 13. A process according to any one of claims 1 to 12, characterised in that the guiding webs (13) are machined by rotating tools (31,32,33) whose axis of rotation (R) perpendicu- larly crosses the longitudinal axis (A) of the inner joint part and whose centre is guided in radial planes which, relative to the inner joint part (11), extend through the longitudinal axis (A). 14. A process according to claim 13, characterised in that the guiding webs (13) are machined by rotating tools whose centre, relative to the inner joint part (11), additionally carries out pivot movements around its longitudinal axis (A). 15. A device for machining inner joint parts (11) of con- stant velocity universal ball joints, which inner joint 22 parts (11) comprise a longitudinal axis (A) and at least one guiding face by means of which the inner joint part (11) is orbitally angularly movably guided in a ball cage, and which comprise a plurality of ball tracks (12) which are distributed around the circumference of the guiding face and which ball tracks divide the guiding face into a corresponding plurality of guiding webs (13) and in which ball tracks torque transmitting balls can be held so as to be longitudinally displaceable, characterised in that it comprises clamping means for an inner joint part (11) and at least two rotating tools (21, 31) for simul- taneously machining at least one ball track (12) and at least one guiding web (13). 16. A device for machining inner joint parts (11) of con- stant velocity universal ball joints, which inner joint parts (11) comprise a longitudinal axis (A) and at least one guiding face by means of which the inner joint part (11) is orbitally angularly movably guided in a ball cage, and which comprise a plurality of ball tracks (12) which are distributed around the circumference of the guiding face and which ball tracks divide the guiding face into a corresponding plurality of guiding webs (13) and in which ball tracks torque transmitting balls can be held so as to be longitudinally displaceable, characterised in that it comprises clamping means for an inner joint part (11) and at least two rotating tools (21, 22) for simul- taneously machining two ball tracks (12, 12') in the 23 longitudinal direction. 17. A device for machining inner joint parts (11) of con- stant velocity universal ball joints, which inner joint parts (11) comprise a longitudinal axis (A) and at least one guiding face by means of which the inner joint part (11) is orbitally angularly movably guided in a ball cage, and which comprise a plurality of ball tracks (12) which are distributed around the circumference of the guiding face and which ball tracks divide the guiding face into a corresponding plurality of guiding webs (13) and in which ball tracks torque transmitting balls can be held so as to be longitudinally displaceable, characterised in that it comprises clamping means for an inner joint part (11) and at least two rotating tools (31, 32) for simul- taneously machining two guiding webs (13, 13') in the longitudinal direction. 18. A device according to any one of claims 16 to 17, characterised in that the clamping means for an inner joint part (11) comprise at least feeding elements to ensure feeding in the longitudinal direction (Z) of the inner joint part and that the at least two rotating tools comprise feed- ing means to ensure feeding only in the radial direction relative to the longitudinal direction of the inner joint part. 24 19. A device according to any one of claims 15 to 18, characterised in that the axes of rotation (R) of all rotating tools which simultaneously engage the inner joint part (11) are positioned in a common plane. 20. A device according to claim 19, characterised in that the axes of rotation (R) of the rotating tools are positioned at least in two parallel planes, wherein more particularly tools for dressing the guiding webs are po- sitioned in a second common plane. 21. A device according to any one of claims 15 to 20, characterised in that the clamping means of the inner joint part (11) ad- ditionally comprise adjusting means for rotatingly ad- justing the clamping means around the longitudinal axis (A) of the inner joint part (11). 22. A device according to any one of claims 15 to 21, characterised in that the rotating tools (21,22,23,24) for the ball tracks (12) are disc tools whose axes of rotation cross the longitudinal axis (A) of the inner joint part (11) at a distance from one another. 25 23. A device according to any one of claims 15 to 21, characterised in that the rotating tools for the ball tracks are finger tools whose axes of rotation are aligned substantially radially relative to the longitudinal axis (A) of the inner joint part (11). 24. A device according to any one of claims 15 to 23, characterised in that the rotating tools (31,32,33) for the guiding webs (13) are disc tools whose axes of rotation cross the longitudinal axis (A) of the inner part (11) at a dis- tance from one another. 25. A device according to any one of claims 15 to 24, characterised in that the clamping means for the inner joint part (11) clamp in the latter axially. 26. A device according to any one of claims 15 to 25, characterised in that there are provided adjusting means for rotatingly adjusting the rotating tools around the longitudinal axis (A) of the inner joint part (11). A process machining inner joint parts 11 of constant velocity universal ball joints, which inner joint parts 11 comprise a longitudinal axis A and at least one guiding face by means of which the inner joint part 11 is continiously angularly movably guided in a ball cage, and which comprise a plurality of ball tracks 12 which are distributed around the circumference of the guiding face and which divide the guiding face into a corresponding plurality of guiding webs 13 and in which torque transmitting balls can be held so as to be longitudinally displaceable, wherein one ball track 12 and at least one guiding web 13 are machined simultaneously.

Full Text

1 GKN Driveline International GmbH 29th November 2004
Hauptstrasse 130 Ne/bec (20040424)
53797 Lohmar Q04017WO00
Process of and device for machining ball hubs
Description
The invention relates to processes of and devices for machin-
ing the inner joint parts of constant velocity universal ball
joints, which inner joint parts are also referred to as ball
hubs. Such inner joint parts have a longitudinal axis A and
comprise at least one guiding face by means of which the inner
joint part is continuously angularly movably guided relative
to the ball cage. On said guiding face there is positioned a
plurality of circumferentially distributed ball tracks which
divide the guiding face into a corresponding plurality of
guiding webs. Torque transmitting balls of the constant veloc-
ity universal ball joint can be longitudinally displaceably
held in the ball tracks. As is generally known, constant ve-
locity universal ball joints of this type comprise an outer
joint part with first ball tracks, a ball cage holding a plu-
rality of balls, as well as the inner joint part which is re-
ferred to here and which has second ball tracks (not explained
in greater detail below). More particularly, but not exclu-
sively, the inner joint parts of the above-described type are
suitable for constant velocity universal ball joints which
are referred to by the applicant as AC (angular contact), UF
(undercut free), DO (double offset), HAI (high angle inboard)
and TBJ (twin ball joint) joints. These designations have
largely developed into standard terms referring to species.

2
When producing prior art inner joint parts it is already known
to subject the workpieces in a common clamping device first to
machining operations on the individual ball tracks and subse-
quently to machining operations on the guiding webs. When ma-
chining the ball tracks, the ball hub is held in position and
by means of rotating tools, the ball tracks are machined track
by track in a chip-forming way. More particularly, the already
hardened tracks are ground. Thereafter, the ball hub, in a ro-
tatingly driven condition, is finish-turned (on outer diame-
ter) and then form-ground.
It is the object of the present invention to further rational-
ise the process of producing ball hubs of said type and to
provide devices for carrying out said process.
A first solution consists in providing a process of machining
the inner joint parts of constant velocity universal joints,
which inner joint parts have a longitudinal axis A and com-
prise at least one guiding face by means of which the inner
joint part is continuously angularly movably guided in a the
ball cage, and which comprises a plurality of ball tracks
which are distributed around the circumference of the guiding
face, which divide the guiding face into a corresponding plu-
rality of guiding webs and in which the torque transmitting
balls can be held so as to be longitudinally displaceable,
which inner joint part is characterised in that at least one
ball track and at least one guiding web are machined in a
chip-forming way simultaneously.
With set-up times which are as advantageous as those used so
far, i.e. by using a clamping device, the inventive process is
suitable for shortening the machining times and for considera-
bly reducing the down-times of the individual tools. Said
chip-forming machining operation can comprise both milling

3
processes and grinding processes as well a combination of the
two. With a given output the investment costs are reduced con-
siderably by the inventive process.
More particularly while adhering to the further embodiments
mentioned below, it is possible to achieve quality improve-
ments, i.e. that in the case of uneven numbers of ball tracks
and guiding webs, one ball track and one radially opposed gui-
ding web are machined simultaneously and that in the case of
even numbers of ball tracks and guiding webs, one ball track
and one guiding web adjoining the radially opposed ball track
are machined simultaneously. In this way, either no
transverse forces or only low transverse forces are applied to
the clamping device for the workpiece, so that the tracks and
guiding webs can be produced with a higher degree of preci-
sion. Because the rotating tools used are form tools, tracks
of any cross-section can be produced.
Production can be increased further in that two ball tracks
and two faces are machined simultaneously or that at least two
- more particularly two ball tracks positioned in planes ex-
tending parallel relative to one another - are simultaneously
machined in the longitudinal direction synchronously and,
with one or two guiding webs being machined at least par-
tially simultaneously thereto.
According to a second solution which substantially has the
same advantages as the above-described solution, there is pro-
posed a process of machining inner joint parts of constant
velocity universal ball joints , which inner joint parts have
a longitudinal axis and comprise at least one guiding face by
means of which the inner joint part is continuously angularly
movably guided in a the ball cage, and which comprises a plu-
rality of ball tracks which are distributed around the circum-

4
ference of the guiding face, which divide the guiding face in-
to a corresponding plurality of guiding webs and in which the
torque transmitting balls can be held so as to be longitu-
dinally displaceable, wherein at least two ball tracks are ma-
chined simultaneously in a chip-forming way in the longitudi-
nal direction.
Finally, according to a third solution which also has the same
advantages as described above, there is proposed a process of
machining inner joint parts of constant velocity universal
ball joints , which inner joint parts have a longitudinal axis
and comprise at least one guiding face by means of which the
inner joint part is continuously angularly movably guided in a
ball cage, and which comprises a plurality of ball tracks
which are distributed around the circumference of the guiding
face, which divide the guiding face into a corresponding plu-
rality of guiding webs and in which the torque transmitting
balls can be held so as to be longitudinally displaceable,
wherein at least two guiding tracks are machined simultane-
ously in a chip-forming way in the longitudinal direction.
With the processes mentioned here it is also possible to
achieve an improvement in quality in that with uneven numbers
of ball tracks and guiding webs, a first ball track or web
face and the second ball track or guiding web adjoining the
radially opposed partial face or ball track are machined si-
multaneously and that with even numbers of ball tracks and
guiding webs, two radially opposed ball tracks or guiding webs
are machined simultaneously. In this case, too, the forces
acting on the workpiece can be largely balanced, so that the
transverse forces and bearing load at the clamping device are
reduced, with the production accuracy being increased.

5
According to a preferred process which will be explained in
more detail with reference to the drawings, the ball tracks
are machined by rotating tools whose axes of rotation inter-
sect the longitudinal axis of the inner joint part perpendicu-
larly and whose centre is guided in radial planes which, rela-
tive to the inner joint part, extend through the longitudinal
axis.
Alternatively, it is possible for the ball tracks to be ma-
chined by rotating tools whose axes of rotation are aligned
substantially radially relative to the longitudinal axis of
the inner joint part, wherein the axis of rotation, rela-
tively, is guided in radial planes extending through the lon-
gitudinal axis of the inner joint part.
With reference to the production of the guiding webs it is
proposed that the guiding webs are machined by rotating tools
whose axis of rotation intersects the longitudinal axis of the
inner joint part perpendicularly and whose centre, relative to
the inner joint part, is guided in radial planes which extend
through the longitudinal axis of the inner joint part because
in view of the hollow shape of the tool face, only disc tools
can be used and not finger tools. In order to make it possible
for several guiding webs to be machined by one tool without
having to rotate the clamped-in workpiece, it is proposed ac-
cording to a further supplementary process that the guiding
webs are machined by rotating tools, whose centre, relative to
the inner joint part, additionally carries out pivot movements
around its longitudinal axis.
In accordance with the initially mentioned objective, the in-
vention furthermore, according to a first proposal, comprises
a device for machining inner joint parts of constant velocity
universal ball joints , which inner joint parts have a longi-

6
tudinal axis and comprise at least one guiding face by means
of which the inner joint part is continuously angularly mova-
bly guided in a ball cage, and which comprises a plurality of
ball tracks which are distributed around the circumference of
the guiding face, which divide the guiding face into a corre-
sponding plurality of guiding webs and in which the torque
transmitting balls can be held so as to be longitudinally dis-
placeable, wherein said device comprises a clamping device for
the inner joint part and at least two rotating tools for si-
multaneously machining at least one ball track and at least
one guiding web in the longitudinal direction.
According to a second solution variant which substantially
leads to the same results, the invention comprises a device of
the above-mentioned species which is characterised in that it
comprises a clamping device for an inner joint part and at le-
ast two rotating tools for simultaneously machining at least
two ball tracks in the longitudinal direction.
According to a further solution variant which also leads to
said advantageous results, there is proposed a device which is
characterised in that it comprises a clamping device for an
inner joint part and at least two rotating tools for simulta-
neously machining at least two guiding webs in the longitudi-
nal direction.
Due to the fact that it is possible to machine simultaneously
a plurality of functional faces of the inventive inner joint
part, productivity is improved with existing investment costs.
The device can be particularly simple in design and cost-
effective if the clamping device for an inner joint part com-
prises feeding means at least for feeding the workpiece in the
longitudinal direction of the inner joint part and if the at
least two rotating tools comprise feeding means to ensure

7
feeding in the radial direction only relative to the longitu-
dinal axis of the inner joint part. In addition it is proposed
that the clamping device additionally comprises adjusting
means for rotatingly adjusting the clamping device around the
longitudinal axis of the inner joint part. More particularly,
the clamping device is able to clamp in the inner joint part
axially.
After the rotating tools have been returned radially out-
wardly, the workpiece can be rotated in its clamping device by
the pitch angle of the ball tracks and the next synchronous
machining operation for two functional faces can be repeated
with the workpiece being fed in entirely axially and with the
rotating tools being moved forward entirely radially. It is
also possible to provide alternative adjusting means for ro-
tatingly adjusting the rotating tools around the longitudinal
axis of the inner joint part.
In a preferred embodiment, the axes of rotation of all rotat-
ing tools participating simultaneously in the machining opera-
tion are positioned in one plane.
According to a further embodiment it is proposed that the axes
of rotation of the rotating tools are positioned in at least
two planes extending parallel relative to one another, wherein
especially the tools for dressing the guiding webs are posi-
tioned in a second common plane. In this way, it is possible,
with simple means, to use further tools, with the clamping de-
vice remaining unchanged. It would not be possible for such
further tools to be accommodated in an annular assembly in one
plane with reference to the longitudinal axis of the work-
piece .

8
As already indicated, the rotating tools for the ball tracks
can be disc tools whose axes of rotation intersect the longi-
tudinal axis of the inner joint part at a distance. However,
the rotating tools for the ball tracks can also be finger
tools which axes of rotation are arranged substantially ra-
dially relative to the longitudinal axis of the inner joint
part. As far as the rotating tools for the web faces are con-
cerned, these have to be provided in the form of disc tools.
Illustrations of preferred embodiments of the inventive proc-
ess from which there are derived preferred embodiments of in-
ventive devices are contained in the drawings and will be de-
scribed below.
Figure 1 shows an inventive process wherein a ball track and a
web face are machined simultaneously
a) in an axial view of the longitudinal axis of the inner
joint part
b) in a radial view of the longitudinal axis of the inner
joint part in a first variant
c) in a radial view of the longitudinal axis of the inner
joint part in a second variant
d) in a radial view of the longitudinal axis of a deviating
inner joint part.
Figure 2 shows an inventive process wherein two ball tracks
and two web faces are machined simultaneously, in an axial
view of the longitudinal axis of the inner joint part.
Figure 3 shows the execution of an inventive process wherein
two ball tracks are machined simultaneously, in an axial view
of the longitudinal axis of the inner joint part.

9
Figure 4 shows the execution of an inventive process wherein
two web faces are machined simultaneously, in an axial view of
the longitudinal axis of the inner joint part.
Figure 5 shows the execution of an inventive process wherein
two parallel ball tracks and one web face are machined simul-
taneously.
Figure la shows the inventive process of machining an inner
joint part 11 of a constant velocity universal joint according
to a first solution. The inner joint parts of constant veloc-
ity universal joints are often also referred to as ball hubs.
The longitudinal axis of the inner joint part 11 has been gi-
ven the reference symbol A and, below, will repeatedly be used
with reference to the arrangement and to the movements of the
tools used. The inner joint part 11 is shown to comprise six
circumferentially distributed ball tracks 12 which, in the
longitudinal direction, comprise a substantially uniform
cross-section and which are shown here as approximately semi-
circular round tracks. The ball tracks 12 are separated from
one another by web faces 13 which are partial faces of an ima-
ginary partially spherical guiding face of the inner joint
part by means of which the inner joint part 11 is guided so as
to be articulatable relative to a ball cage. It is common
practice for said guiding face to be a disc portion of a ball.
However, the guiding face can also be interrupted by a central
over-turning, so that, as an imaginary guiding face, it forms
two axially spaced ball discs between which there is posi-
tioned a non-guiding intermediate portion. At the guiding webs
13 and at the delimiting edges of the ball tracks 12 it is
possible to identify chamfers 14, 15 which are irrelevant for
the inventive production process. The inner joint part 11 com-
prises a through-aperture 16 which extends coaxially relative
to the longitudinal axis A and comprises inner shaft teeth 17

10
which are provided for inserting a drive shaft journal. There
are provided a first rotating tool 21 constituting a form tool
for rotatingly machining the ball tracks 12 as well as a sec-
ond rotating tool 31 constituting a rotating form tool for ma-
chining the guiding webs 13, which rotating tools 21, 31, in
accordance with the invention, engage the inner joint part si-
multaneously. The axis of rotation of the tools 21 has been
given the reference symbol R21 and the axis of rotation of the
tool 31 has been given the reference symbol R31. The two axes
X21 and X31 which intersect the longitudinal axis A in the same
point and whose significance will be referred to in connection
with the following figure each extend perpendicularly relative
to the direction of the longitudinal axis A. An arch-shaped
arrow P shown in dash-dotted lines indicates the possibility
of adjusting the tools 21, 31 relative to the inner joint part
11, with the centre of movement being positioned on the longi-
tudinal axis A. However, said possibility of movement consti-
tutes one option only. Alternatively, a holding element for
the inner joint part 11 can be designed so as to be rotatingly
adjustable.
Figures lb, lc show the process and the device according to
Figure la in an angled longitudinal section through the axis A
and the axes X21, X31. The inner joint part 11 is shown to com-
prise an aperture 16 which extends coaxially relative to the
longitudinal axis A and comprises inner teeth 17. One of the
ball tracks 12 is shown to engage the rotating tool 21. One of
the web faces 13 is shown to engage the rotating tool 31. The
movement of the tools 21, 31 relative to the inner joint part
11 is such that the inner joint part 11 is moved entirely axi-
ally on the clamping axis Z in the direction of the double ar-
row Z11, whereas the rotating tools 21, 31 are each moved en-
tirely in the direction of the double arrows X12, X113 along the
axes X21, X31. The axes X21, X31 are positioned in a common plane

11
which extends radially relative to the clamping axis Z; ac-
cording to Figure lb they coincide and according to Figure lc
they are offset in parallel relative to one another. In order
to change over to machining a further ball track and a further
web face after a ball track 12 and a web face 13 have been
fully machined simultaneously, the tools 21, 31 can be moved
out of the engagement with the inner joint part 11 radially
relative to the clamping axis Z, and the inner joint part 11
can be rotated around the clamping axis Z by a pitch angle of
the ball tracks 12. The necessary types of movement and con-
trol of the device are thus the rotation of the clamping de-
vice and the displacement of the clamping device in direction
Z as well as an entirely axial displacement of the axes of
rotation R21, R31 along the radial axes X21, X31.
Figure 1d shows a process and a device similar to those shown
in Figure la for a deviating inner joint part 11 in an angled
longitudinal section through the axis A and the axes X21, X31.
The inner joint part 11 is axially clamped into a two-part
clamping device 18. The inner joint part 11 can be seen to
comprise a through-aperture 16 extending coaxially relative to
the longitudinal axis A. One of the straight ball tracks 12
engages the rotating tool 21. One of the web faces 13 engages
the rotating tool 31. The path of the tools 21, 13 relative to
the inner joint part 11 has been indicated by dash-dotted li-
nes. The actual movement, however, is such that the inner
joint part 11 is moved on the clamping axis Z entirely axially
in the direction of the double arrow Z11 whereas the rotational
tools 21, 13 are moved entirely in the direction of the double
arrows X12, X13 along the axes X21, X31, the former operation be-
ing only for setting purposes and the latter operation taking
place during the entire process. The axes X21, X31 are posi-
tioned in a common plane extending radially relative to the
clamping axis Z. In order to change over to machining a fur-

12
ther ball track and a further web face after a ball track 12
and a web face 13 have been fully machined simultaneously, the
tools 21, 31 can be moved out of the engagement with the inner
joint part 11 radially relative to the clamping axis Z, and
the inner joint part 11 can be rotated around the clamping
axis Z by a pitch angle of the ball tracks 12. The necessary
types of movement and control of the device are thus the rota-
tion of the clamping device 18 and the displacement of the
clamping device 18 in direction Z as well as an entirely ra-
dial displacement of the axes of rotation R21, R31 along the
radial axes X21, X31.
As can be seen in Figure la, it is advantageous if, for the
purpose of balancing the forces, the two tools 21, 31 are ar-
ranged largely radially opposite one another. With the even
number of ball tracks 12 shown here, it is necessary to devi-
ate from said ideal by half a pitch angle of the ball tracks.
If the chip-forming machining process requires several succes-
sive stages such as milling and grinding, further sets of
pairs of tools can be arranged in planes extending parallel to
the drawing plane of Figure la, so that the inner joint part
11, without having to be re-clamped and while using the en-
tirely axial feeding facilities can be fed to the further
set(s) of tools. These sets of tools, too, require only one
axial feeding facility in the radial direction with reference
to the clamping axis Z.
Figure 2 shows a modified and further embodiment of the proc-
ess illustrated in Figure 1, again in an axial view of the
longitudinal axis A of the inner joint part 11 analogously to
Figure la. Identical details have been given the same refer-
ence numbers as in Figure 1, so that reference is made to the
description of same. In addition to the rotating tool 21 for

13
the ball track 12, there is shown a deviating second tool 22
for a ball track 12' positioned radially opposite. Further-
more, in addition to the tool 31 for the web region 13, there
is illustrated a further identical tool 32 for a web 13' posi-
tioned radially opposite. The axes X21, X31 form a 90° angle, so
that at the inner joint part 11, during the chip-forming ma-
chining operation, the forces are largely balanced with refer-
ence to the clamping axis Z, i.e. in contrast to the embodi-
ment according to Figure 1, no resulting forces act on the
clamping axis Z. In this case, the device is preferably de-
signed in such a way that the inner joint part 11 is displace-
able along the clamping axis Z and, for the purpose of chang-
ing between the individual machining operations, it can be ro-
tated around the clamping axis, whereas the tools 21, 22, 31,
32 can only be moved in the direction of the individual axes
X21, X22, X31, X32.
Figure 3 shows the inventive machining process according to a
third solution, again illustrating an inner joint part 11 in
an axial view of the longitudinal axis A. Identical details
have been given the same reference numbers as in the preceding
figures, so that reference is made to the description of same.
In accordance with the invention, two ball tracks 12, 12' are
subjected to a chip-forming machining operation simultaneously
by two rotating tools 21, 22 which correspond to those shown
in Figure 2 and, in the same way, engage radially opposed ball
tracks. In this case, too, an axial feeding operation takes
place along the longitudinal axis A of the inner joint part 11
along the clamping axis Z and, in addition, the inner joint
part 11 is rotatable around the axis Z by the track pitch an-
gle (a). In contrast hereto, the axes of the rotatingly driven
tools 21, 22 can move in the direction of the double arrows
X12, X12' in the radial direction relative to the clamping axis
Z. Their axes of movement X21, X22 are positioned in a common

14
plane, i.e. more particularly on a common straight line. In
accordance with the arrow P' shown in dash-dotted lines, it is
possible, in this case, too, to allow the tools 21, 22 to be
adjustable relative to the inner joint part 11 around the cen-
tre of movement A.
Figure 4 shows an inventive machining process according to a
fourth solution, again showing the inner joint part 11 in an
axial view of the longitudinal axis. Identical details have
been given the same reference numbers as the preceding fig-
ures, so that reference is made to the description of same. In
accordance with the invention, two web regions 13, 13' are ma-
chined simultaneously by two rotating tools 31', 32 which cor-
respond to those shown in Figure 2 and which, in the same way,
engage radially opposed ball tracks. In this case, too, the
longitudinal axis A of the inner joint part is fed forward
along the clamping axis Z, and, in addition, the inner joint
part is rotatable around the axis Z by the track pitch angle
(a). On the other hand, the rotatingly driven tools 31', 32
can move their axes only in the direction of the double arrows
X13, X13' in the radial direction relative to the clamping axis
Z. Their axes of movement X32', X32 are positioned in a common
plane, i.e. more particularly on a common straight line. In
accordance with the dash-dotted arrow P", this case, too, al-
lows the tools 31', 32 to be adjustable relative to the inner
joint part 11 around the centre of movement A.
Figure 5 shows a further embodiment of an inventive process,
wherein the inner joint part 11 comprises ball tracks 12]., 122
which extend in pairs arranged in parallel relative to one an-
other and which form first wider web regions 131 positioned be-
tween two pairs and second narrower web regions 132 positioned
between the two tracks 121, 122 of a pair. In this case, the
tracks 121, 122 of a pair are machined by two rotating tools 23,

15
24 which comprise a common axis of rotation R23 and are rotat-
ingly drivably held in a common holding device 25. The holding
device 25 and thus the tools 23, 24 move radially relative to
the longitudinal axis A of the inner joint part and to the
clamping axis Z in the direction of the radial ray X23. The web
regions 131, 132 are each machined by a rotating tool 33 which
comprises an axis of rotation R33 and is rotatingly drivably
received in a holding device 34. The holding device 34 and
thus also the tool 33 again move radially relative to the lon-
gitudinal axis A of the inner joint part 11 and thus to the
clamping axis in the direction of the radial ray X33. In this
case, too, the axes R32, R33 are preferably positioned in a com-
mon plane. A dash-dotted arrow P"' indicates that the holding
device 34 is additionally adjustable relative to the holding
device 25 so that the holding device 34 can be adjusted from
machining the web region 131 (as illustrated) to machining the
web region 132 around the centre of movement A without there
being a need to rotate the workpiece around the clamping axis.
Only after the operation of machining two web regions 131, 132,
which takes place at least partially simultaneously with the
machining of the tracks 121, 122, has been completed, is the
workpiece 11 rotated around its clamping axis by the pitch an-
gle between the pairs of tracks, i.e. in this case by 90°. The
holding device 34 is pivoted back into its starting position.
Alternatively, with the workpiece 11 being held in a fixed po-
sition, it is possible for both holding devices 25, 34 to be
adjusted jointly relative to the fixed workpiece 11 around the
centre of movement A.
Modifications of the above-described process are possible, for
example by additionally providing two tools for simultaneously
machining two web regions, but which two tools have to com-
prise different axes of rotation.

16
GKN Driveline International GmbH 29th November 2004
Hauptstrasse 130 Ne/bec (20040424)
53797 Lohmar Q04017WO00
Process of and device for machining ball hubs
List of reference numbers
11 inner joint part
12 ball track
13 guiding web/web face
14 chamfer
15 chamber
16 through-aperture
17 teeth
18 clamping device
19 -
20 -
21 tool
22 tool
23 tool
24 tool
25 tool
31 tool
32 tool
33 tool
34 tool
A longitudinal axis
Z clamping axis
R axis of rotation
X radial axis

17
GKN Driveline International GmbH 2 9th November 2004
Hauptstrasse 130 Ne/bec (20040424)
53797 Lohmar Q04017WO00
Process of and device for machining ball hubs
Claims
1. A process of machining inner joint parts (11) of con-
stant velocity universal ball joints, which inner joint
parts (11) comprise a longitudinal axis (A) and at least
one guiding face by means of which the inner joint part
(11) is orbitally angularly movably guided in a ball
cage, and which comprise a plurality of ball tracks (12)
which are distributed around the circumference of the
guiding face and which ball tracks divide the guiding
face into a corresponding plurality of guiding webs (13)
and in which ball tracks torque transmitting balls can
be held so as to be longitudinally displaceable,
characterised in
that one ball track (12) and at least one guiding web
(13) are machined simultaneously.
2. A process according to claim 1,
characterised in
that in the case of uneven numbers of ball tracks (12)
and guiding webs (13), one ball track (12) and one ra-
dially opposed guiding web (13) each are machined simul-
taneously.

18
3. A process according to claim 1,
characterised in
that in the case of even numbers of ball tracks (12) and
guiding webs (13), one ball track (12) and one guiding
web (13) adjoining the radially opposed ball track each
are machined simultaneously.
4. A process according to any one of claims 1 to 3,
characterised in
that two ball tracks (12) and two guiding webs (13) each
are machined simultaneously.
5. A process according to any one of claims 1 to 3,
characterised in
that two ball tracks (12) - more particularly two ball
tracks positioned in planes extending parallel relative
to one another - are simultaneously machined in the lon-
gitudinal direction synchronously and at least one guid-
ing web (13) is machined at least partially simultane-
ously therewith.
6. A process according to claim 5,
characterised in
that two ball tracks positioned in planes extending par-
allel relative to one another are machined by jointly
driven tools (23, 24) .

19
7. A process of machining inner joint parts (11) of con-
stant velocity universal ball joints, which inner joint
parts (11) comprise a longitudinal axis (A) and are pro-
vided with at least one guiding face by means of which
the inner joint part (11) is guided orbitally angularly
movably guided in a ball cage and which comprise a plu-
rality of ball tracks (12) which are distributed around
the circumference of the guiding face, which ball tracks
divide the guiding face into a corresponding number of
guiding webs (13) and in which ball tracks torque trans-
mitting balls are held so as to be longitudinally dis-
placeable,
characterised in
that at least two ball tracks (12) are machined simulta-
neously in the longitudinal direction.
8. A process of machining inner joint parts (11) of con-
stant velocity universal ball joints, which inner joint
parts (11) comprise a longitudinal axis (A) and are pro-
vided with at least one guiding face by means of which
the inner joint part (11) is guided orbitally angularly
movably in a ball cage and which comprise a plurality of
ball tracks (12) which are distributed around the cir-
cumference of the guiding face, which ball tracks divide
the guiding face into a corresponding number of guiding
webs (13) and in which ball tracks torque transmitting
balls are held so as to be longitudinally displaceable,
characterised in

20
that at least two guiding webs (13, 13') are machined
simultaneously in the longitudinal direction.
9. A process according to any one of claims 7 or 8,
characterised in
that, in the case of uneven numbers of ball tracks (12)
and guiding webs (13), a first ball track (12) or web
face (13) and the second ball track (12') or guiding web
(13') adjoining the radially opposed web face or ball
track each are machined simultaneously.
10. A process according to any one of claims 7 or 8,
characterised in
that, in the case of even numbers of ball tracks (12)
and guiding webs (13), two radially opposed ball tracks
(12, 12') or guiding webs (13, 13') each are machined
simultaneously.
11. A process according to any one of claims 1 to 10,
characterised in
that the ball tracks (12) are machined by rotating tools
(21,22,23,24) whose axes of rotation (R) perpendicularly
cross the longitudinal axis (A) of the inner joint part
(11) and whose centre is guided in radial planes (X)
which, relative to the inner joint part (11), extend
through the longitudinal axis (A).

21
12. A process according to any one of claims 1 to 10,
characterised in
that the ball tracks (12) are machined by rotating tools
whose axis of rotation extends substantially radially
relative to the longitudinal axis (A) of the inner joint
part (11), wherein the axis of rotation, relative to the
inner joint part (11) , is guided in radial planes ex-
tending through the longitudinal axis (A) of the inner
joint part (11). (No Figure).
13. A process according to any one of claims 1 to 12,
characterised in
that the guiding webs (13) are machined by rotating
tools (31,32,33) whose axis of rotation (R) perpendicu-
larly crosses the longitudinal axis (A) of the inner
joint part and whose centre is guided in radial planes
which, relative to the inner joint part (11), extend
through the longitudinal axis (A).
14. A process according to claim 13,
characterised in
that the guiding webs (13) are machined by rotating
tools whose centre, relative to the inner joint part
(11), additionally carries out pivot movements around
its longitudinal axis (A).
15. A device for machining inner joint parts (11) of con-
stant velocity universal ball joints, which inner joint

22
parts (11) comprise a longitudinal axis (A) and at least
one guiding face by means of which the inner joint part
(11) is orbitally angularly movably guided in a ball
cage, and which comprise a plurality of ball tracks (12)
which are distributed around the circumference of the
guiding face and which ball tracks divide the guiding
face into a corresponding plurality of guiding webs (13)
and in which ball tracks torque transmitting balls can
be held so as to be longitudinally displaceable,
characterised in
that it comprises clamping means for an inner joint part
(11) and at least two rotating tools (21, 31) for simul-
taneously machining at least one ball track (12) and at
least one guiding web (13).
16. A device for machining inner joint parts (11) of con-
stant velocity universal ball joints, which inner joint
parts (11) comprise a longitudinal axis (A) and at least
one guiding face by means of which the inner joint part
(11) is orbitally angularly movably guided in a ball
cage, and which comprise a plurality of ball tracks (12)
which are distributed around the circumference of the
guiding face and which ball tracks divide the guiding
face into a corresponding plurality of guiding webs (13)
and in which ball tracks torque transmitting balls can
be held so as to be longitudinally displaceable,
characterised in
that it comprises clamping means for an inner joint part
(11) and at least two rotating tools (21, 22) for simul-
taneously machining two ball tracks (12, 12') in the

23
longitudinal direction.
17. A device for machining inner joint parts (11) of con-
stant velocity universal ball joints, which inner joint
parts (11) comprise a longitudinal axis (A) and at least
one guiding face by means of which the inner joint part
(11) is orbitally angularly movably guided in a ball
cage, and which comprise a plurality of ball tracks (12)
which are distributed around the circumference of the
guiding face and which ball tracks divide the guiding
face into a corresponding plurality of guiding webs (13)
and in which ball tracks torque transmitting balls can
be held so as to be longitudinally displaceable,
characterised in
that it comprises clamping means for an inner joint part
(11) and at least two rotating tools (31, 32) for simul-
taneously machining two guiding webs (13, 13') in the
longitudinal direction.
18. A device according to any one of claims 16 to 17,
characterised in
that the clamping means for an inner joint part (11)
comprise at least feeding elements to ensure feeding in
the longitudinal direction (Z) of the inner joint part
and that the at least two rotating tools comprise feed-
ing means to ensure feeding only in the radial direction
relative to the longitudinal direction of the inner
joint part.

24
19. A device according to any one of claims 15 to 18,
characterised in
that the axes of rotation (R) of all rotating tools
which simultaneously engage the inner joint part (11)
are positioned in a common plane.
20. A device according to claim 19,
characterised in
that the axes of rotation (R) of the rotating tools are
positioned at least in two parallel planes, wherein more
particularly tools for dressing the guiding webs are po-
sitioned in a second common plane.
21. A device according to any one of claims 15 to 20,
characterised in
that the clamping means of the inner joint part (11) ad-
ditionally comprise adjusting means for rotatingly ad-
justing the clamping means around the longitudinal axis
(A) of the inner joint part (11).
22. A device according to any one of claims 15 to 21,
characterised in
that the rotating tools (21,22,23,24) for the ball
tracks (12) are disc tools whose axes of rotation cross
the longitudinal axis (A) of the inner joint part (11)
at a distance from one another.

25
23. A device according to any one of claims 15 to 21,
characterised in
that the rotating tools for the ball tracks are finger
tools whose axes of rotation are aligned substantially
radially relative to the longitudinal axis (A) of the
inner joint part (11).
24. A device according to any one of claims 15 to 23,
characterised in
that the rotating tools (31,32,33) for the guiding webs
(13) are disc tools whose axes of rotation cross the
longitudinal axis (A) of the inner part (11) at a dis-
tance from one another.
25. A device according to any one of claims 15 to 24,
characterised in
that the clamping means for the inner joint part (11)
clamp in the latter axially.
26. A device according to any one of claims 15 to 25,
characterised in
that there are provided adjusting means for rotatingly
adjusting the rotating tools around the longitudinal
axis (A) of the inner joint part (11).

A process machining inner joint parts 11 of constant velocity
universal ball joints, which inner joint parts 11 comprise a
longitudinal axis A and at least one guiding face by means of
which the inner joint part 11 is continiously angularly movably guided in a ball cage, and which comprise a plurality of
ball tracks 12 which are distributed around the circumference
of the guiding face and which divide the guiding face into a
corresponding plurality of guiding webs 13 and in which torque
transmitting balls can be held so as to be longitudinally displaceable, wherein one ball track 12 and at least one guiding
web 13 are machined simultaneously.

Documents:

01304-kolnp-2007-abstract.pdf

01304-kolnp-2007-claims.pdf

01304-kolnp-2007-correspondence others 1.1.pdf

01304-kolnp-2007-correspondence others 1.2.pdf

01304-kolnp-2007-correspondence others 1.3.pdf

01304-kolnp-2007-correspondence others.pdf

01304-kolnp-2007-description complete.pdf

01304-kolnp-2007-drawings.pdf

01304-kolnp-2007-form 1.pdf

01304-kolnp-2007-form 2.pdf

01304-kolnp-2007-form 3.pdf

01304-kolnp-2007-form 5.pdf

01304-kolnp-2007-gfa.pdf

01304-kolnp-2007-international publication.pdf

01304-kolnp-2007-international search report.pdf

01304-kolnp-2007-others.pdf

01304-kolnp-2007-pct request.pdf

01304-kolnp-2007-priority document.pdf

1304-KOLNP-2007-(29-08-2011)-PETITION UNDER RULE 137.pdf

1304-KOLNP-2007-ABSTRACT-1.1.pdf

1304-KOLNP-2007-AMANDED CLAIMS.pdf

1304-KOLNP-2007-AMANDED PAGES OF SPECIFICATION.pdf

1304-KOLNP-2007-DESCRIPTION (COMPLETE)-1.1.pdf

1304-KOLNP-2007-DRAWINGS-1.1.pdf

1304-KOLNP-2007-EXAMINATION REPORT REPLY RECIEVED.pdf

1304-KOLNP-2007-FORM 1-1.1.pdf

1304-kolnp-2007-form 18.pdf

1304-KOLNP-2007-FORM 2-1.1.pdf

1304-KOLNP-2007-FORM 3-1.1.pdf

1304-KOLNP-2007-FORM 5-1.1.pdf

1304-KOLNP-2007-OTHERS-1.1.pdf

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Patent Number

251283

Indian Patent Application Number

1304/KOLNP/2007

PG Journal Number

10/2012

Publication Date

09-Mar-2012

Grant Date

05-Mar-2012

Date of Filing

13-Apr-2007

Name of Patentee

GKN DRIVELINE INTERNATIONAL GMBH

Applicant Address

HAUPTSTRASSE 130, D-53797 LOHMAR

Inventors:

#	Inventor's Name	Inventor's Address
1	CREMERIUS, ROLF	WEIMARSTRASSE 40, 53757 ST. AUGUSTIN

PCT International Classification Number

F16D 3/223

PCT International Application Number

PCT/EP2004/013794

PCT International Filing date

2004-12-03

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA