Title of Invention

"CENTER CLAMP"

Abstract

A center clamp (1) for holding a workpiece (6) as it is machined in a grinding apparatus where material is removed, in particular by a cup wheel, characterized by the following: a) the center clamp (1) has a generally C-shaped body (2) with opposite ends (3) laterally offset in the same direction; b) a push rod (4) passes through one of the ends (3); c) the push rod (4) can be forcibly shifted in a straight line relative to the body (2) along an axis for axial clamping; d) the push rod (4) and the workpiece (6) can be pivoted by actuators about the axis for angularly aligning the workpiece (6); e) a controller operates the actuators; f) the other of the ends (3) of the body (2) is provided with a support rod including a rotary joint (5) and pressing the workpiece (6) axially against the push rod (4) ; g) the rotary joint (5) has a generally rotation- symmetrical concave seat part (11) and a generally rotation- symmetrical support part (12) sitting therein; h) both the support part (12) and the seat part (11) are generally rotation-symmetrical to the axis (A); and i) the center clamp (1) is made small compared to the cup wheel.

Full Text

TRANSLATION I Center clamp The invention relates to a center clamp for holding a workpiece as it is machined in a grinding apparatus where material is removed in particular by a cup wheel. Such a center clamp is known in practice. In it the workpiece to be machined is held between two rods and the center clamp is constructed as an expensive and fairly tall device. Both the drive for angularly orienting the gripped workpiece as well as the actuator for exerting the gripping force are at one end of the center clamp while the gripping force passes through a force- transmitting element to the other end and is there applied by a rocker arrangement to avoid deformations of the center clamp from the gripping force being exerted. j The disadvantage with this system is that such known center clamps are only limitedly pivotal as a result of their large size, and cannot normally be swung down into a standard cup wheel since the available space is relatively limited and the center clamp must not touch the edge of the cup wheel. Hence when all the edges of the workpiece must be machined it is necessary that such center clamps be made axially relatively long in order that the necessary machining can take place on the far side of the grinding wheel, since there the required pivoting is possible without the possibility of contact. As a result of the long travel, machining with such a clamp is relatively slow and the long axial reach reduces the stiffness of the machining system leading to sloppier machining results. t It is an object of the invention to avoid the above-mentioned disadvantageous and provide a center clamp that allows a workpiece to be machined when the workpiece must be pivoted into the grinding wheel. This object is attained by a center clamp for holding a workpiece as it is machined in a grinding apparatus where material is removed, in particular by a cup wheel, characterized by the following features: a) the center clamp has a generally C-shaped body with opposite ends laterally offset in the same direction; b) a push rod passes through one of the ends; c) the push rod can be forcibly shifted in a straight line relative to the body along an axis for axial clamping; ' d) the push rod and the workpiece can be pivoted by actuators about the axis for angularly aligning the workpiece; e) a controller operates the actuators; f) the other of the ends of the body is provided with a support rod including a rotary joint and pressing the workpiece axially against the push rod; g) the rotary joint has a generally rotation-symmetrical concave seat part and a generally rotation-symmetrical support part sitting therein; h) both the support part and the seat part are generally ? rotation-symmetrical to the axis (A); and i) the center clamp is made small compared to the cup wheel (body length e.g. about 6 to-10 cm, in particular about 8 cm) . In this manner the center clamp with the gripped workpiece can be pivoted into virtually any position relative to the grinding wheel without any contact between the grinding wheel and the clamp. As a. result virtually any location on the workpiece gripped by the center clamp can be machined without having to.shift the center clamp over a long axial distance relative to the grinding wheel. In addition the force transmission is moment-free, so that no stiffening parts or expensive guides are needed. Furthermore the lever can be swivelmounted between its both ends. The stability and stiffness of the entire device can be further increased, thereby producing better machining results and reducing machining time. As a result of the relatively short height substantial stiffness is obtained with much less actual structure so that the cost of such a device is substantially reduced. Preferably the support part is formed as a. cap-shaped ball segment of such a radius of curvature that its center of curvature lies generally at a center of the workpiece generally equispaced between push-rod/workpiece and rotary-joint/workpiece contact zones. The support part can also be made cylindrical or frustoconical with a correspondingly curved upper end face. The radius of curvature of the seat part is slightly smaller than the radius of curvature of the support part so that there is annular contact in an outer region. The center region forms a small lubricant pocket and the centering action is improved. * According to the invention the support part can lie between the workpiece and the bearing part of the rotary joint, although the opposite arrangement is also possible. Advantageously a tube or the like is provided to hold the support part against unintentional displacement so that without using expensive parts there is good functionality. As a result of the limited rotation at the rotary joint such a protective arrangement is satisfactory. The arrangement can be a shrink sleeve. In this system the support element can be slightly tapered, as a result of which the use of a tube protector or the like provides even better protection against unintended disconnection. In a preferred embodiment the diameter of the rods is very small, in particular only a few millimeters, so that even a relatively small workpiece, e.g. cutting plates with an inner periphery of only a few millimeters, can be machined without problems. According to the invention the support element is harder than the seat part so that wear takes place on the support part. Thus the seat part is made of hardened steel or another hardened metal and the support part of plain steel. In addition the support and seat parts can both be made of the same material, e.g. a hardened metal, so that greater wear or material erosion of one of the parts is avoided. Preferably, for axially gripping the workpiece, the body is held against axial movement, the push rod is forcibly movable relative to the body, and an actuator is provided for operating the push rod, pressing the push rod in particular against a resistance force toward the seat part. In addition, for axially gripping the workpiece, the body is held against axial movement, the push rod is urged, in particular spring biased, relative to the body toward the seat part, and an actuator is provided for shifting the push rod axially in one direction against the resistance force and axially in the opposite direction for periodically releasing gripping by the push rod, so that no expensive structure for actuation through the drive spindle is needed. Alternatively, for axially gripping the workpiece, the push rod is held against axial movement, the body is forcibly shiftable relative to the push rod, and an actuator is provided for shifting the body axially against the resistance force toward the push rod. In addition, for axially gripping the workpiece, the body is held against axial movement, the push rod is urged, in particular spring biased, relative to the body toward the seat part, and an actuator is provided for shifting the push rod axially in one direction against the resistance force and axially in the opposite direction for periodically releasing gripping by the push rod. Here the actuator can be part of the drive spindle of the push rod. In addition the actuator can be formed as at least one lever or the like engaging a projection of the structure to be moved, so that in a technically simple structure a robust and effective actuator construction is possible. In this system the Lever has a forked end with two projecting parts laterally gripping the projection of the structure to be moved and preferably the projecting parts are spaced from each other at the axis of the structure to be moved, e.g. the push rod, so that as a result of moment-free force transmission canting or the like is avoided and the above-discussed small dimension of the object of the invention are retained. The fork can be engages at a portion of the body that is on the outside of the center clamp. In a preferred embodiment of the invention the push rod has, in order to increase the surface pressure where the workplace is gripped, a recess, in particular a seat, having an inner projecting annular region so that the moment transferred by friction to the workpiece is greater and slip is avoided between the push rod and the workpiece. Rotation thus takes place in the rotary joint and not where the push rod contacts the workpiece. The contact interface with the push rod can be formed by an annular surface forming a pocket. The invention also relates to a grinding apparatus wherein material removal is effected by means of a grinding wheel, in particular a cup wheel, with a center clamp for holding the workpiece during machining, and having a center clamp for holding the workpiece during machining. The disadvantages of the prior-art grinding apparatuses have already been described and are avoided in a grinding apparatus provided with a center clamp of the above-described type. An embodiment of the invention shown in the drawing is described in the following. Therein: FIG. 1 is a partly sectional side view of a center clamp according to the invention; FIG. 2 is the structure of FIG. 1 in a partly sectional top view; FIG. 3 is a prior-art clamp; and FIGS. 4 and 5 are schematic illustrations of the clamp according to the invention. In all figures the same or similar parts are identified with the same reference numerals. FIG. 1 shows in sectional view an embodiment of a center clamp 1 for a workpiece 6. The center clamp 1 has a generally C-shaped body 2 having ends 3 offset laterally in the same direction. A push rod 4 projects through one end of the clamp body 2 and the other end 3 of the body 2 is provided with a rotary joint 5 serving as support for the workplace 6 engaged by the push rod 4, the relative position of the push rod 4 and the clamp body 2 being changeable for axial gripping. In the illustrated embodiment for axial gripping of the workpiece 6 the push rod 4 is axially offset, the clamp body 2 can be forcibly moved angularly relative to the push rod 4, and an actuator 7 is provided for pressing the push rod 4 toward the clamp body 2. As shown in FIG. 2 the actuator 7 has a fork-shaped lever 8 with two projecting lateral ends 9, which ends 9 engage corresponding faces of a groove on a projection 10 of the body 2 to be displaced. As a result of the groove-like shape shown in the drawing the actuator 7 can also be set to axially release the clamp and axially adjust the amount the clamp 1 is opened to allow fitting-in and taking-out of the workpiece 6. To this end the fork-shaped lever 8 together with the C-shaped body in this embodiment are responsible for moving the push rod and the push rod 4 functions as a stationary abutment relative to the drive. The push rod 4 can be rotated to angularly align the workpiece 6 by means of unillustrated actuators. The rotary joint 5 has a generally rotation-symmetrical concave seat part 11 and, sitting on and coacting with it, a generally rotation-symmetrical convex support part 12, both oriented so that the centers of the faces of the parts 11 and 12 lie on the axis (A) of the body 2. A sleeve holder 13 constituted as a shrink tube prevents unintentional disconnection of the support part 12. FIGS. 3, 4, and 5 show how much smaller a clamp according to the invention (FIGS. 4 and 5) is than a prior-art clamp (FIG. 3). We claim: ( 1. A center clamp (1) for holding a workpiece (6), as it is machined in a grinding apparatlls where material is removed, in particular by a cup wheel, characterized by the following: . . a) the ~enter clamp (1) has a generally C-shaped body (2) with opposit~ ends (3) laterally offset in the same dh'ectionj b) a push rod (4) passes through one of the ends (3); c) the push rod (4) can be forcibly shifted in a straight line relativ~ to the body (2) along an rods for axial clamping; eI) the push rod (4) and the workpiece (6) can be pivoted by actuators about the axis for angularly aligning the workpiece (6); e) a controller operates the actuators; 1) the other of the ends (3) of the body (2) is provided with a support rod including a rotary joint (5) and pressing the workpiece (6) axially· against the push rod (4); g) the' rotaty joint (5) has a generally rotation:- symmetrical concave seat part (11) and a generally rotation syinmetrlcal support part (12) sitting therein; h) both the support part (12) and the seat part (11) are generally rotationsymmetrical to the.axis (A); and i) the center' damp (1) is made small compared to the cup wheeL -11- 2. The center clamp (1) as claimed in claim 1, whel'ein the support part (12) is formed as a cap-shaped ball segment of such a radius of curvature that its center of curvli\.t\,lre Jies generally at a center of the workpiece (6) generally equi&paced between push-rod/workpiece and rotary joint/workpiece contact zones. 3. The center clamp as c1atmed in claim 1 or 2, wherein Hie' radius of curvature ofthe seat part (11) is slightly smaller than the radius of curvature of the support part (12). 4. The center clamp (1) as claimed in one· of claims 1 to 3, wherein the support part (12) lies between the workpiece (6) and the bearing part (11) of the rotary joint (5). 5. The center clamp (1) as claimed in claim 4, wherein the support part (12) is axially tapered. 6. The center clamp (1) as claimed in one of claims 1 to 5, wherein a tube (13) or the like is provided to hold the support part (12) against unintentional displacement. 7. 'I'he center clamp as claimed in one of claiJ;lls 1 to 6, wherein the diameter of the rods is velY small, in particular only a few millimeters. 8. The center clamp as claime~ in one of claims 1 to 7, wherein the support part (12) is harder than the seatpatt (ll). 9. The center clamp (l) as claimed in one of claim 1 to 8, wherein for axially gripping the workpiece (5) the body (2) is held against axial -=12- ( I( r ( movement, the push rod (4) is forcibly movable relative to the body (2), and an,actuator'for operating the push rod (4) is provided pressing the. push rod (4) in particular against a resistance force toward the seat part (11). 10. The center clamp (1) as claimed in one of claim 1 to 8j wherein, for axially gripping the workpiece (6), the body (2) is held against axial movement,the push rod (4) is urged, in particular spring biased, relative to the body (2) toward the seat part (11),. and an actuator (7) is provided for shifting the push rod (11) axially in one directi~n against the resistance force and axially in the opposite direction Jor periodically releasing gripping by the push rod (4). 11. 'fhe center clamp as claimed in one of claims 1 to 8, wherein, fOl' axially gl'ipping the workpiece (6), the push l'Od (4) is held against axial movement, the body (2) is forcibly shiftable relative to the push rod (4), and an actuator (7) is provided for shifting the body (2) axially against the resistance force toward the push rod (4). 12. 'l'he center clamp (1) as claimed in one of claims 1 to B, wherein, for axially gripping the work.piece (6), the push rod (4) is held against axial movement, the body (2) is forcible shiftable, in particulal'1y.with spring biasing, relative to the push rod (4), and an actuator (7) is pmvided for shifting the body (2) axially against the resistance force away from the push fod (4) for periodically l'eleasing gripping by the body (2). 13. The center clamp (1) as claimed in one of claims 9 to 12, wherein the actuator (7) is part of a drive shaft for the push rod (4). 14. The center clamp (1) as ·claimed in one of claims 9 to 12, wherein the actuator (7) is formed as at least one lever (8) or the like engaging a projection (10) of the structure to be moved.. -13- ( ( 15. The center clamp (I) as claimed in claim 14, wherein the lever (8) has a forked end with two projecting parts (9) laterally grippj~g the projection (10) o~ the structure to be moved. 16. The center clamp (I) as claimed in claim 15, wherein the projecting parts (l0) are spaced Crom each other at the aXis of the structure to be moved. ' 17. The cente"r clamp (1) as claimed in one of claims 14 to 16, wherein the lever (8) is swivelmounted between its both ends. 18. The center clamp (I) as claimed in one of claims 1 to 17, wherein the push" rod (4) has, in order to increase the surface pressure where the workpiece (6) is gripped, a recess, in particular a seat having an inner projecting annual region. 19. A grinding apparatus wherein matedal l'emoval is effected by means of grinding wheel, in particular a cup wheel, with a center clamp for holding the workpiece duing machining, wherein a center clamp as claimed in one of claims 1 to 18 is used. 20. The center clamp as claimed in claim 1 or 2, wherein the radius oflit CUl'vatut'e of the support part (12)- is slightly smaller than the radius of curvature/! 't':;;"h" of the seat pat (11)

Documents:

548-del-2005-Abstract-(22-05-2014).pdf

548-del-2005-abstract.pdf

548-del-2005-Claims-(10-06-2009).pdf

548-del-2005-Claims-(22-05-2014).pdf

548-del-2005-claims.pdf

548-del-2005-Correspondence Others-(18-03-2014).pdf

548-del-2005-Correspondence Others-(22-05-2014).pdf

548-del-2005-Correspondence-Others-(04-04-2011).pdf

548-del-2005-Correspondence-Others-(10-06-2009).pdf

548-DEL-2005-Correspondence-Others-(21-03-2011).pdf

548-DEL-2005-Correspondence-Others-(24-02-2011).pdf

548-del-2005-correspondence-others.pdf

548-del-2005-Description (Complete)-(22-05-2014).pdf

548-del-2005-description (complete).pdf

548-del-2005-Drawings-(22-05-2014).pdf

548-del-2005-drawings.pdf

548-del-2005-form-1.pdf

548-del-2005-Form-13-(10-06-2009).pdf

548-del-2005-form-13.pdf

548-del-2005-form-18.pdf

548-del-2005-form-2.pdf

548-del-2005-Form-24-(04-04-2011).pdf

548-del-2005-Form-3-(10-06-2009).pdf

548-del-2005-form-3.pdf

548-DEL-2005-Form-4-(24-02-2011).pdf

548-del-2005-Form-5-(22-05-2014).pdf

548-del-2005-form-5.pdf

548-del-2005-GPA-(18-03-2014).pdf

548-del-2005-gpa.pdf