Title of Invention	HOLDER FOR A WORKPIECE OR TOOL HAVING A TAPERED COLLAR
Abstract	The Invention relates to an apparatus for holding a (2) or tool having a tapered collar (1) or the like and having a pull-back rod (4) axially shift able in a body (3) for actuating a chuck head (6) cooperating with jaws (5). The axial position of the pill-back rod (4) is maintained in the holding position without utilizing the force of a tension spring by means of a self-locking mechanism FIG. 1)

Title of Invention

HOLDER FOR A WORKPIECE OR TOOL HAVING A TAPERED COLLAR

Abstract

The Invention relates to an apparatus for holding a (2) or tool having a tapered collar (1) or the like and having a pull-back rod (4) axially shift able in a body (3) for actuating a chuck head (6) cooperating with jaws (5). The axial position of the pill-back rod (4) is maintained in the holding position without utilizing the force of a tension spring by means of a self-locking mechanism FIG. 1)

Full Text	HOLDER FOR A WDRKPIECE OR TOOL HAVINS A TAPERED COLLAR The invention relates to an apparatus for holding a workpiece or tool having a hollow tapered collar or the like, the apparatus having a pull-back rod axially shift able in a body for actuating a chuck head cooperating with jaws. The actuation of such an apparatus is carried out by axially moving the pull-back rod, it being tensioned for holding and compressed for releasing the holding of the workpiece or tool and shifting again into the releasing position. In order to hold the axial position a£ the pull-back rod in the holding position, it is common according to prior art to prestress it by means of a tension spring, usually using a stack of spring washers or bolt disk springs that press the pull-back rod into the holding position with great force and hold it in place even if tension is no longer applied to the pill-back rod. However, one disadvantage is that the balance of the rotating spindle of the machine tool supporting the apparatus is adversely affected by the stack o£ spring washers. The invention is therefore based on the object providing an apparatus of the above-mentioned type in such a manners that the abidance can be improved. This object is attained according to the invention in an apparatus of the above mentioned type in that the axial position of the pull-back rod is mEd.ntained in the holding position in a self-locking manner without utilizing the force of a tension spring. Such an apparatus provides the advantage that after the force has been applied, the tension can be released and the stored force will be stored by the self--locking action in the pull-back rod without requiring a tension spring* The balance of the rotating spindle of the machine tool is significantly improved and higher rotational speeds can be achieved. Furthermore, this creates the advantage that essentially is simplified because the required components can be simply inserted into the body axially from the front without being obstructed by the tension spring* It is especially preferred within the scope of the invention, if a holding sleeve is axially fixed on the body and axially guides a gripper whose inner face bears on the pull-back rod, and the pull-back rod has a tapered head, the gripper has a wedge ring, and the holding sleeve has a tapered inner surface The tapered heel, the wedge ring, and the tapered inner surface, created the required high holding force by moue’s of axial relative displacement of the components involved to maintain the required security to safely clanp the workpiece or the tool at high rotation speeds. It is further advantageous when the tapered head is stepped in toward the pull-back rod at a shoulder, the gripper has elm inner ridge for engaging the shoulder, mad the gripper can spread and move past the shoulder with its inner ridge in the axial region of the tapered inner surface of the holding sleeve This configuration initially ensures that the axial displacement of the pull-back rod into the holding position is transmitted via the gripper as a large axial displacement of the chuck head to press the jaws against the tapered collar and produce the clasping effect and movement of the pill-back rod along the wedge ring spreads the grlpper outward and engages it with the tapered head. Although axial displacement of the grlpper is reduced in this manner with a given axial stroke of the pull-back rod, self-locking action occurs, however, with Increasing force, in that the wedge ring is literally wedged between the tapered head and the tapered inner surface of the holding sleeve This position of the grlpper Is maintained even if axial tension on the pull-back rod is released so that the pull-back rod can rotate out of contact with the spindle of the machine tool and any actuating system It is further provided within the scope of the invention that the grlpper Is coupled to the chuck head for axial displacement thereof via a threaded bolt, as well as via a threaded ring. In principle, the possibility exists to allow the grlpper to directly act upon the chuck head, such enibodiroent providing advantages with the use of the threaded bolt and the threaded ring with regard to the manufacture, installation, and c ool ant throughput. In order to avoid any rotation of the grlpper relative to the chuck head’ which could lead to a lateral off-center position of the grlpper resulting in the creation of an undefined holding force, the grlpper is guided in a longitudinal slot of the holding sleeve It has proven advantageous within the scope of the invention, if the tapered head has an apex angle of 4E to 8E, particularly of 6E, since this angle advantageously meets the requirements for a sufficient axial displacement of the grlpper during displacement of the pull-back rod when the grlpper is pressed against the tapered inner surface of the holding This is facilitated; if the tapered inner surface of the holding sleeve has an apex angle of 9E to 15E particularly of 12E, whereby in this case the inner surface of the wedge ring purposefully has an angle corresponding to the apex angle of the tapered head, and the outer surface of the wedge ring has an angle corresponding to the apex angle of the holding sleeve for ensuring a large engagement surface Furthermore; it is advantageous if the tapered head has an engagement surface that comes bears on the threaded ring, if the inner ridge of the gripper engages the shoulder of the tapered head. This configuration ensures that the gripper is moved jointly with the pull-back rod without any clearance from the releasing position into the holding position, i. a the gripper engages the shoulder of the pull-back rod flush with its inner ridge In the following the invention is explained in greater detail with reference to an embodiment shown in the drawing; the sole FIG. 1 shows a longitudinal section through the apparatus according to the invention. The drawing shows an apparatus serving to hold a workpiece 2 or a tool having a frustoconically tapered collar 1, to which end the apparatus has a pull-back rod 4 that is axially e in body 3 and that serves for actuating a chuck head 6 cooperating with jaws 5, namely by axial displacement of the pull-back rod 4 between a releasing position shown in the drawing in the bottom half and a holding position shown in the upper half of the drawing. For holding the workpiece 2 the pull-back rod 4 is pulled from the greasing position back into the holding position by means of actuator not shown in the drawing’ so that the chuck head 6 is axially displaced via a tong-like gripper 7, a threaded bolt 8, and a threaded ring 9, thus radially outwardly displacing the outer jaw ends 10 of the jaws 5 into engagement with the tapered collar 1. It is important in the apparatus shown in the drawing that a holding sleeve 11 is axially fixed in the body 1 and axially guides the gripper 7 that bears with its inner faces on the pull-back rod 4 that has a tapered head 12, the gripper 7 having a radially spread able wedge ring 13 and the holding sleeve 11 having a frustoconical inner surface 14 that on movement of the pull-back rod 4 from the releasing position into the holding position creates a self-locking action that maintains the axial position of the gripper 7 without even having to maintain tension on the pull-back rod 4 with the actuator. The force applied to the pull-back rod 4 by the actuator is therefore in effect stored by means o£ this self-locking roechanisnv and the safe holding of the workpiece 2 at its tapered collar 1 is ensured without having to exploit a tension spring that has to maintain the axial position of the pull-back rod 4 in the holding position with its tension against the body 3 or the holding sleeve 11* Such safe holding is therefore not compromised by any fatigue on the part o£ the tension spring. Furthermore; with the use of the self-locking mechanism provided by the invention the pull-back rod 4 is not engaged by a tension spring and can rotate with the spindle or the body 3 without having to be connected to its actuator so that balance is improved and rotational speed can be increased. The drawing further shows that the tapered head 12 is stepped radially in at a shoulder 15 toward the pull-back rod 4, the gripper 7 has an inner ridge 16 for engageznent with the shoulder 15, and the gripper 7 nay spread and pass the shoulder 15 with the inner ridge 16 in the region of the tapered inner surface 14 of the holding sleeve 11. In the embodiment shown in the drawing the tapered head 12 has an apex audible of 6E, while the tapered inner surface 14 of the holding sleeve 11 has an apex angle of 12E. The angle of the inner surface’ as well as that of the outer surface of the wedge ring 13 correspond to the angle of the respective confronting surfaces. The operation of the apparatus is briefly below. Based on the releasing position shown in the bottom had-f, tension is applied to the pill-back rod 4 by the unillustrat ed actuator, by means of which the rod 4 is pulled back to the left in the drawing. This covenant causes the pull-back rod 4 to engage the inner ridges 16 of the gripper 7 on the coiler of the pull-back bolt 4 first to entrain the gripper 7 that, in order to avoid an unbalance are guided in two slots 17 of the tightening sleeve, and thus via the threaded bolt 8 and the threaded ring 9 entrains the head 6 so that the outer ends 10 of the jaws 5 pivot outward and engage a shoulder 18 of the tapered collar 1. The engagement of the shoulder 15 with the inner ridge 16 effects a rapid axial movement of the chuck head 6 and after moving through a predetermined short axial stroke the inner ridge 16 of the gripper 7 spreads and moves axially past the shoulder 15 while riding on the inner surface cC the wedge ring 13 c’ the tapered head and simultaneously the outer surface of the wedge ring presses against the tightening sleeve 11. With continued axial movement of the pull-back rod 4. the gripper 7 is therefore entrained through a very short axial stroke and then is wedged between the tapered head 12 and the holding sleeve 11 with increased force’ until the mechanism self-locks, thereby providing the desired tension even if the actuator is disconnected from the pull-back rod 4, If the holding is to be released, the pull-back rod 4 is pushed left to right from the holding position into the releasing position, thus releasing the gripper 7 wedged between the tapered head 12 and the holding sleeve 11, and the pull-back rod 4 also novas relative to the gripper 7 until it engages the threaded ring 9 with its end 19, and the inner ridge 16 can again engage behind the shoulder 15 of the pull-back rod 4, Continued movement of the pull-back rod 4 pushes the chuck head 6 so that the jaws 5 release the workpiece 2 with their outer jaw ends 10. Patent CI aims: 1. An apparatus for holding a workplace (2) or a tool having a tapered collar (1) or the like, having a pull-back rod (4) axially shift able in a body (3) for actuating a chuck head (6) cooperating with jaws (5)/ characterized in that the axial position of the pull-back rod (4) is maintained in the holding position without utilizing the force of a tension spring by means of a self-locking mechanism 2. The apparatus according to claim 1, characterized in that a holding sleeve (11) is axially fixed in the body (3) axially guides a gripper (7) having an inner surface engaging the pull-back rod (4) and that the pull-back rod (4) has a tapered head (12); the gripper (7) has a wedge ring, and the holding sleeve (11) has a frustoconical inner surface (14). 3. The apparatus according to claims 1 or 2, characterized in that the tapered head (12) is stepped back toward the pull-back rod (4) at a shoulder (15), that the gripper (7) has an inner ridge (16) for engagement with the shoulder (15) , and that the gripper (7) may spread and pass the shoulder (15) with their inner ridge (16) in the axial region of a frustoconical inner surface (14) of the holding sleeve (11). 4. The apparatus according to claim 3, characterized in that the gripper (7) is coupled to the chuck head (6) for axially shifting it by means a£ a threaded bolt (8) and a threaded ring (9). 5* The apparatus according to one of the clause 2 to 4, characterized in that the gripper (7) is guided in at least one longitudinal slot (17) of the holding sleeve (11). 6. The apparatus according to one of the claims 2 to 5’ characterized in that the tapered head (12) has an apex angle of 4E to 8E, patricianly of 6E. 7. The apparatus according to one of the claims 2 to 6 ‘ characterized in that the frustoconical inner surface (14) of the holding sleeve (11) has an apex angle of 9E to 15E, particularly of 12E. 8. The apparatus according to claims 6 or 1, characterized in that the inner surface of the wedge ring (13) has an. apex angle corresponding to the apex angle of the tapered head (12), and the outer surface of the wedge ring (13) has an apex angle corresponding to the apex angle of the holding sleeve (11). 9. The apparatus according to one of the claims 3 to 8, characterized in that the tapered head (12) has a surface (19) that is level with the threaded ring (9) when the inner ridge (16) cf the gripper (7) engages behind the shoulder (15) of the tapered head (12),

Full Text

HOLDER FOR A WDRKPIECE OR TOOL HAVINS A TAPERED COLLAR
The invention relates to an apparatus for holding a workpiece or tool having a hollow tapered collar or the like, the apparatus having a pull-back rod axially shift able in a body for actuating a chuck head cooperating with jaws.
The actuation of such an apparatus is carried out by axially moving the pull-back rod, it being tensioned for holding and compressed for releasing the holding of the workpiece or tool and shifting again into the releasing position. In order to hold the axial position a£ the pull-back rod in the holding position, it is common according to prior art to prestress it by means of a tension spring, usually using a stack of spring washers or bolt disk springs that press the pull-back rod into the holding position with great force and hold it in place even if tension is no longer applied to the pill-back rod. However, one disadvantage is that the balance of the rotating spindle of the machine tool supporting the apparatus is adversely affected by the stack o£ spring washers.
The invention is therefore based on the object providing an apparatus of the above-mentioned type in such a manners that the abidance can be improved.
This object is attained according to the invention in an apparatus of the above mentioned type in that the axial position of the pull-back rod is mEd.ntained in the holding position in a self-locking manner without utilizing the force of a tension spring.
Such an apparatus provides the advantage that after the force has been applied, the tension can be released and the stored

force will be stored by the self--locking action in the pull-back rod without requiring a tension spring* The balance of the rotating spindle of the machine tool is significantly improved and higher rotational speeds can be achieved. Furthermore, this creates the advantage that essentially is simplified because the required components can be simply inserted into the body axially from the front without being obstructed by the tension spring*
It is especially preferred within the scope of the invention, if a holding sleeve is axially fixed on the body and axially guides a gripper whose inner face bears on the pull-back rod, and the pull-back rod has a tapered head, the gripper has a wedge ring, and the holding sleeve has a tapered inner surface The tapered heel, the wedge ring, and the tapered inner surface, created the required high holding force by moue’s of axial relative displacement of the components involved to maintain the required security to safely clanp the workpiece or the tool at high rotation speeds.
It is further advantageous when the tapered head is stepped in toward the pull-back rod at a shoulder, the gripper has elm inner ridge for engaging the shoulder, mad the gripper can spread and move past the shoulder with its inner ridge in the axial region of the tapered inner surface of the holding sleeve This configuration initially ensures that the axial displacement of the pull-back rod into the holding position is transmitted via the gripper as a large axial displacement of the chuck head to press the jaws against the tapered collar and produce the clasping effect and movement of the pill-back rod along the wedge ring

spreads the grlpper outward and engages it with the tapered head. Although axial displacement of the grlpper is reduced in this manner with a given axial stroke of the pull-back rod, self-locking action occurs, however, with Increasing force, in that the wedge ring is literally wedged between the tapered head and the tapered inner surface of the holding sleeve This position of the grlpper Is maintained even if axial tension on the pull-back rod is released so that the pull-back rod can rotate out of contact with the spindle of the machine tool and any actuating system
It is further provided within the scope of the invention that the grlpper Is coupled to the chuck head for axial displacement thereof via a threaded bolt, as well as via a threaded ring. In principle, the possibility exists to allow the grlpper to directly act upon the chuck head, such enibodiroent providing advantages with the use of the threaded bolt and the threaded ring with regard to the manufacture, installation, and c ool ant throughput.
In order to avoid any rotation of the grlpper relative to the chuck head’ which could lead to a lateral off-center position of the grlpper resulting in the creation of an undefined holding force, the grlpper is guided in a longitudinal slot of the holding sleeve
It has proven advantageous within the scope of the
invention, if the tapered head has an apex angle of 4E to 8E,
particularly of 6E, since this angle advantageously meets the requirements for a sufficient axial displacement of the grlpper during displacement of the pull-back rod when the grlpper is

pressed against the tapered inner surface of the holding
This is facilitated; if the tapered inner surface of the holding sleeve has an apex angle of 9E to 15E particularly of 12E, whereby in this case the inner surface of the wedge ring purposefully has an angle corresponding to the apex angle of the tapered head, and the outer surface of the wedge ring has an angle corresponding to the apex angle of the holding sleeve for ensuring a large engagement surface
Furthermore; it is advantageous if the tapered head has an engagement surface that comes bears on the threaded ring, if the inner ridge of the gripper engages the shoulder of the tapered head. This configuration ensures that the gripper is moved jointly with the pull-back rod without any clearance from the releasing position into the holding position, i. a the gripper engages the shoulder of the pull-back rod flush with its inner ridge
In the following the invention is explained in greater detail with reference to an embodiment shown in the drawing; the sole FIG. 1 shows a longitudinal section through the apparatus according to the invention.
The drawing shows an apparatus serving to hold a workpiece 2 or a tool having a frustoconically tapered collar 1, to which end the apparatus has a pull-back rod 4 that is axially e in body 3 and that serves for actuating a chuck head 6 cooperating with jaws 5, namely by axial displacement of the pull-back rod 4 between a releasing position shown in the drawing in the bottom half and a holding position shown in the upper half

of the drawing. For holding the workpiece 2 the pull-back rod 4 is pulled from the greasing position back into the holding position by means of actuator not shown in the drawing’ so that the chuck head 6 is axially displaced via a tong-like gripper 7, a threaded bolt 8, and a threaded ring 9, thus radially outwardly displacing the outer jaw ends 10 of the jaws 5 into engagement with the tapered collar 1.
It is important in the apparatus shown in the drawing that a holding sleeve 11 is axially fixed in the body 1 and axially guides the gripper 7 that bears with its inner faces on the pull-back rod 4 that has a tapered head 12, the gripper 7 having a radially spread able wedge ring 13 and the holding sleeve 11 having a frustoconical inner surface 14 that on movement of the pull-back rod 4 from the releasing position into the holding position creates a self-locking action that maintains the axial position of the gripper 7 without even having to maintain tension on the pull-back rod 4 with the actuator. The force applied to the pull-back rod 4 by the actuator is therefore in effect stored by means o£ this self-locking roechanisnv and the safe holding of the workpiece 2 at its tapered collar 1 is ensured without having to exploit a tension spring that has to maintain the axial position of the pull-back rod 4 in the holding position with its tension against the body 3 or the holding sleeve 11* Such safe holding is therefore not compromised by any fatigue on the part o£ the tension spring. Furthermore; with the use of the self-locking mechanism provided by the invention the pull-back rod 4 is not engaged by a tension spring and can rotate with the spindle or the body 3 without having

to be connected to its actuator so that balance is improved and rotational speed can be increased.
The drawing further shows that the tapered head 12 is stepped radially in at a shoulder 15 toward the pull-back rod 4, the gripper 7 has an inner ridge 16 for engageznent with the shoulder 15, and the gripper 7 nay spread and pass the shoulder 15 with the inner ridge 16 in the region of the tapered inner surface 14 of the holding sleeve 11. In the embodiment shown in the drawing the tapered head 12 has an apex audible of 6E, while the tapered inner surface 14 of the holding sleeve 11 has an apex angle of 12E. The angle of the inner surface’ as well as that of the outer surface of the wedge ring 13 correspond to the angle of the respective confronting surfaces.
The operation of the apparatus is briefly below. Based on the releasing position shown in the bottom had-f, tension is applied to the pill-back rod 4 by the unillustrat ed actuator, by means of which the rod 4 is pulled back to the left in the drawing. This covenant causes the pull-back rod 4 to engage the inner ridges 16 of the gripper 7 on the coiler of the pull-back bolt 4 first to entrain the gripper 7 that, in order to avoid an unbalance are guided in two slots 17 of the tightening sleeve, and thus via the threaded bolt 8 and the threaded ring 9 entrains the head 6 so that the outer ends 10 of the jaws 5 pivot outward and engage a shoulder 18 of the tapered collar 1. The engagement of the shoulder 15 with the inner ridge 16 effects a rapid axial movement of the chuck head 6 and after moving through a predetermined short axial stroke the inner ridge 16 of the gripper

7 spreads and moves axially past the shoulder 15 while riding on the inner surface cC the wedge ring 13 c’ the tapered head and simultaneously the outer surface of the wedge ring presses against the tightening sleeve 11. With continued axial movement of the pull-back rod 4. the gripper 7 is therefore entrained through a very short axial stroke and then is wedged between the tapered head 12 and the holding sleeve 11 with increased force’ until the mechanism self-locks, thereby providing the desired tension even if the actuator is disconnected from the pull-back rod 4,
If the holding is to be released, the pull-back rod 4 is pushed left to right from the holding position into the releasing position, thus releasing the gripper 7 wedged between the tapered head 12 and the holding sleeve 11, and the pull-back rod 4 also novas relative to the gripper 7 until it engages the threaded ring 9 with its end 19, and the inner ridge 16 can again engage behind the shoulder 15 of the pull-back rod 4, Continued movement of the pull-back rod 4 pushes the chuck head 6 so that the jaws 5 release the workpiece 2 with their outer jaw ends 10.

Patent CI aims:
1. An apparatus for holding a workplace (2) or a tool having a tapered collar (1) or the like, having a pull-back rod (4) axially shift able in a body (3) for actuating a chuck head (6) cooperating with jaws (5)/ characterized in that the axial position of the pull-back rod (4) is maintained in the holding position without utilizing the force of a tension spring by means of a self-locking mechanism
2. The apparatus according to claim 1, characterized in that a holding sleeve (11) is axially fixed in the body (3) axially guides a gripper (7) having an inner surface engaging the pull-back rod (4) and that the pull-back rod (4) has a tapered head (12); the gripper (7) has a wedge ring, and the holding sleeve (11) has a
frustoconical inner surface (14).
3. The apparatus according to claims 1 or 2, characterized in that the tapered head (12) is stepped back toward the pull-back rod (4) at a shoulder (15), that the gripper (7) has an inner ridge (16) for engagement with the shoulder (15) , and that the gripper (7) may spread and pass the shoulder (15) with their inner ridge (16) in the axial region of a frustoconical inner surface (14) of the holding sleeve (11).
4. The apparatus according to claim 3, characterized in that the gripper (7) is coupled to the chuck head (6) for axially

shifting it by means a£ a threaded bolt (8) and a threaded ring (9).
5* The apparatus according to one of the clause 2 to 4,
characterized in that the gripper (7) is guided in at least one longitudinal slot (17) of the holding sleeve (11).
6. The apparatus according to one of the claims 2 to 5’ characterized in that the tapered head (12) has an apex angle of 4E to 8E, patricianly of 6E.
7. The apparatus according to one of the claims 2 to 6 ‘ characterized in that the frustoconical inner surface (14) of the
holding sleeve (11) has an apex angle of 9E to 15E, particularly of
12E.
8. The apparatus according to claims 6 or 1, characterized in that the inner surface of the wedge ring (13) has an. apex angle corresponding to the apex angle of the tapered head (12), and the outer surface of the wedge ring (13) has an apex angle corresponding to the apex angle of the holding sleeve (11).
9. The apparatus according to one of the claims 3 to 8, characterized in that the tapered head (12) has a surface (19) that is level with the threaded ring (9) when the inner ridge (16) cf

the gripper (7) engages behind the shoulder (15) of the tapered head (12),

Documents:

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Patent Number

272950

Indian Patent Application Number

1233/CHENP/2008

PG Journal Number

19/2016

Publication Date

06-May-2016

Grant Date

04-May-2016

Date of Filing

12-Mar-2008

Name of Patentee

ROHM GMBH

Applicant Address

HEINRICH-ROHM-STRASSE 50, 89567 SONTHEIM, GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	HANGLEITER, EUGEN	KRONENSTRASSE 3, 89268 HERMARINGEN, GERMANY

PCT International Classification Number

B23B31/20

PCT International Application Number

PCT/DE06/01016

PCT International Filing date

2006-06-14

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	102005043722.2	2005-09-13	Germany
2	102005049377.7	2005-10-15	Germany