Collet

Abstract

A circular flexible collet that provides a 360 degree gripping engagement with a cylindrical workpiece and which is operable by an actuator member incorporated in a workpiece chuck. The collet may be constructed as an internal collet for gripping engagement with a workpiece internal periphery, or as an external collet for gripping engagement with a workpiece external periphery. The flexible collet may be used for single, or plural workpiece gripping actions. The collet includes a split spring steel body having a radial opening split space and an outer and an inner circular periphery. One circular periphery is a workpiece gripping surface, and the other circular periphery has a tapered cam surface engageable by a workpiece chuck actuator member. The tapered cam surface has a plurality of circumferentially spaced apart slots, having an open outer end. In an internal collet the tapered cam surface is formed around the collet body inner periphery. In an external collet the tapered cam surface is formed around the collet body outer periphery.

What is claimed is:  
     
       1. In a collet chuck having a chuck body provided with at least one circular collet seat, a circular collet mounted on said collet seat, a movable power operated actuator means slidably mounted on the chuck body for engagement with said collet to bias it into a gripping engagement with a circular periphery on a cylindrical-like workpiece when the actuator means is moved in one direction, a return means mounted on the chuck body in engagement with the actuator means for moving the actuator means in another direction to release the collet gripping engagement with the cylindrical-like workpiece, the improvement comprising: 
       (a) said circular collet having a flexible circular collet body which has an outer circular periphery and an inner circular periphery;  
       (b) said flexible circular collet body having a radial opening formed therethrough which extends between said outer and inner peripheries;  
       (c) one of said collet body circular peripheries having a workpiece gripping surface and the other of said collet body circular peripheries having a tapered cam surface engageable by said actuator means to bias the collet into said engagement with said workpiece; and,  
       (d) said tapered cam surface having a plurality of circumferentially spaced apart slots, and each of said slots has an open outer end and an arcuate inner end.  
     
     
       2. A collet chuck as defined in claim  1 , wherein: 
       (a) an elastomeric seal is mounted in the radial opening in said circular collet body.  
     
     
       3. A collet chuck as defined in claim  1 , wherein: 
       (a) said circular collet body has a plurality of radial openings formed therethrough.  
     
     
       4. A collet chuck as defined in claim  3  wherein: 
       (a) an elastomeric seal is mounted each of said plurality of radial openings in said circular collet body.  
     
     
       5. A collet chuck as defined in claim  1 , wherein: 
       (a) a closure tang is mounted on the collet body and extends over the radial opening.  
     
     
       6. A collet chuck as in any of claims  1 - 5 , in which the collet body has a hole formed at an inner arcuate end of each of said plurality of slots in said tapered cam surface, and the axis of each hole is parallel to and spaced radially apart from the workpiece gripping surface. 
     
     
       7. A collet chuck as in any of claim  1 - 5 , in which the workpiece gripping surface is formed on the outer circular periphery of the collet body for gripping an internal surface of a cylindrical-like workpiece, and the tapered cam surface is formed on the inner circular periphery of the collet body. 
     
     
       8. A collet as in any of claims  1 - 5 , in which the workpiece gripping surface is formed on the inner circular periphery of the collet body for gripping an external surface of a cylindrical-like workpiece, and the tapered cam surface formed on the outer circular periphery of the collet body. 
     
     
       9. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with two longitudinally spaced apart circular collet seats;  
       (b) a circular collet is mounted on each of said collet seats;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the outer circular periphery of each of the collet bodies for gripping an internal surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the inner circular periphery of each of the collet bodies; and,  
       (d) one of said circular collets is disposed radially outward from the other circular collet to permit the circular collets to engage a stepped internal surface of a cylindrical-like workpiece when the tapered cam surface on each of the collets is engaged by the actuator means to expand the collets into a gripping engagement with a stepped internal surface of a cylindrical-like workpiece.  
     
     
       10. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with two longitudinally spaced apart circular collet seats;  
       (b) a circular collet is mounted on each of said collet seats;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the outer circular periphery of each of the collet bodies for gripping an internal surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the inner circular periphery of each of the collet bodies; and,  
       (d) said chuck has a pair of actuator means and the tapered cam surface on each of the collets is engaged by one of the actuator means to expand the collets into a gripping engagement with an internal surface of a cylindrical-like workpiece.  
     
     
       11. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with two longitudinally spaced apart circular collet seats and a pair of actuator means;  
       (b) a circular collet is mounted on each of said collet seats;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the outer circular periphery of each of the collet bodies for gripping an internal surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the inner circular periphery of each of the collet bodies; and,  
       (d) the workpiece gripping surfaces on said circular collets are provided with different tapered outer circular peripheries to permit the circular collets to engage a tapered internal surface of a cylindrical-like workpiece when the tapered cam surface on each of the collets is engaged by one of the actuator means to expand the collets into a gripping engagement with a tapered internal surface of a cylindrical-like workpiece.  
     
     
       12. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with two longitudinally spaced apart circular, tapered collet seats, with one of said tapered collet seats being formed as a fixed tapered seat on the chuck body and the other tapered seat being formed on the actuator means;  
       (b) a circular collet is mounted on each of said tapered collet seats, and each of the circular collets has a top end and a bottom end;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the outer circular periphery of each of the collet bodies for gripping an internal surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the inner circular periphery of each of the collet bodies; and,  
       (d) the circular collets are disposed with their bottom ends in abutting engagement with each other, and with the tapered cam surface on one circular collet seated on said fixed tapered collet seat on the chuck body to permit the circular collets to engage an internal surface of a cylindrical-like workpiece when the tapered cam surface on one of the collets is engaged by the tapered seat on the actuator means, and the tapered cam surface on the other collet is engaged by the fixed tapered collet seat, to bias both collets endwise and expand the collets into a gripping engagement with an internal surface of a cylindrical-like workpiece.  
     
     
       13. A collet chuck as defined in claim  1 , wherein: 
       (a) said circular collet body has a top end and a bottom end, and a pair of diametrically opposite disposed radial openings formed therethrough, and a pair of diametrically opposite disposed anchor slots formed in the bottom end of the collet body on a diametrical axis perpendicular to a diametrical axis of the pair of radial openings;  
       (b) the collet body has a hole formed at an inner arcuate end of each of said plurality of slots in said tapered cam surface, and the axis of each hole is parallel to the workpiece gripping surface;  
       (c) the workpiece gripping surface is formed on the outer circular periphery of the collet body for a gripping engagement with the internal surface of a cylindrical-like workpiece, and the tapered cam surface is formed on the inner circular periphery of the collet body; and,  
       (d) a pair of anchor pins are fixedly mounted in a pair of diametrically spaced apart, longitudinal bores in the chuck body with the outer ends of the anchor pins positioned inside of the anchor slots formed in the bottom of the collet body, whereby when the tapered cam surface on the collet body is engaged by the actuator means, the collet body is expanded into a gripping engagement with the internal surface of a cylindrical-like workpiece and the anchor pins coact with the anchor slots in the collet body to prevent rotational slippage of the collet body during machining operations on a cylindrical-like workpiece.  
     
     
       14. A collet chuck as defined in claim  1 , wherein: 
       (a) said collet body comprises an inner primary internal collet, around which is concentrically and telescopically disposed an outer circular secondary, size enlarging internal collet;  
       (b) the collet body of said inner primary internal collet has a hole formed at an inner arcuate end at each of said plurality of slots in said tapered cam surface, and the axis of each hole is parallel to the workpiece gripping surface;  
       (c) the workpiece gripping surface of the inner primary internal collet body is formed on the outer circular periphery of the primary internal collet body for gripping engagement with the inner peripheral surface of the outer circular secondary, size enlarging internal collet, and the tapered cam surface is formed on the inner circular periphery of the collet body of the inner primary internal collet;  
       (d) the outer secondary, size enlarging internal collet has a collet body with atop end which is planar and parallel to a bottom end thereof which is also planar, and the collet body of the outer circular secondary, size enlarging internal collet body has an outer periphery surface, and an inner peripheral surface and each of the last mentioned surfaces are vertical, concentric surfaces which are also concentric with the outer peripheral workpiece engaging surface of the inner primary internal collet body; and,  
       (e) the outer circular secondary, size enlarging internal collet body is provided with a plurality of slots which each extend radially outward from the inner peripheral surface thereof and terminate at an outer end with a hole, and the outer circular secondary, size enlarging internal collet body has a radial opening formed therethrough, whereby when the tapered cam surface on the collet body of the inner primary internal collet is engaged by the actuator means, the inner primary internal collet and the outer circular secondary, size enlarging internal collet are expanded into a gripping engagement with the internal surface of a cylindrical-like workpiece.  
     
     
       15. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with two longitudinally spaced apart circular collet seats;  
       (b) a circular collet is mounted on each of said collet seats;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the inner circular periphery of each of the collet bodies for gripping an external surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the outer circular periphery of each of the collet bodies; and,  
       (d) said chuck has a pair of actuator means and the tapered cam surface on each of the collets is engaged by one of the actuator means to contract the collets into a gripping engagement with an external surface of a cylindrical-like workpiece.  
     
     
       16. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with two longitudinally spaced apart circular collet seats and a pair of actuator means;  
       (b) a circular collet is mounted on each of said collet seats;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the inner circular periphery of each of the collet bodies for gripping an external surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the outer circular periphery of each of the collet bodies; and,  
       (d) the workpiece gripping surfaces on said circular collets are provided with different tapered inner circular peripheries to permit the circular collets to engage a tapered outer surface of a cylindrical-like workpiece when the tapered cam surface on each of the collets is engaged by one of the actuator means to contract the collets into a gripping engagement with a tapered external surface of a cylindrical-like workpiece.  
     
     
       17. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with a plurality of longitudinally spaced apart, stepped circular collet seats;  
       (b) a circular collet is mounted on each of said collet seats;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the inner circular periphery of each of the collet bodies for gripping a stepped external surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the outer periphery of each of the collet bodies; and,  
       (d) said chuck has a plurality of actuator means and the tapered cam surface on each of the circular collets is engaged by one of the actuator means to contract the collets into a gripping engagement with the stepped external surface of a cylindrical-like workpiece.  
     
     
       18. A collet chuck as defined in claim  1 , wherein: 
       (a) said chuck is provided with two longitudinally spaced apart circular, tapered collet seats, with one of said tapered collet seats being formed as a fixed tapered seat on the chuck body and the other tapered seat being formed on the actuator means;  
       (b) a circular collet is mounted on each of said tapered collet seats, and each of the circular collets has a top end and a bottom end;  
       (c) the workpiece gripping surface on each of said circular collets is formed on the inner circular periphery of each of the collet bodies for gripping an external surface of a cylindrical-like workpiece, and the tapered cam surface on each of the circular collets is formed on the outer circular periphery of each of the collet bodies; and,  
       (d) the circular collets are disposed with their bottom ends in abutting engagement with each other, and with the tapered cam surface on one circular collet seated on said fixed tapered collet seat on the chuck body to permit the circular collets to engage an external surface of a cylindrical-like workpiece when the tapered cam surface on one of the collets is engaged by the tapered seat on the actuator means, and the tapered cam surface on the other collet is engaged by the fixed tapered collet seat, to bias both collets endwise and contract the collets into a gripping engagement with an external surface of a cylindrical-like workpiece.  
     
     
       19. A collet chuck as defined in claim  1 , wherein: 
       (a) said circular body has a top end and a bottom end, and a pair of diametrically opposite disposed radial openings formed therethrough, and a pair of diametrically opposite disposed anchor slots formed in the bottom end of the collet body on a diametrical axis perpendicular to a diametrical axis of the pair of radial openings;  
       (b) the collet body has a hole formed at an inner arcuate end of each of said plurality of slots in said tapered cam surface, and the axis of each hole is parallel to the workpiece gripping surface;  
       (c) the workpiece gripping surface is formed on the inner circular periphery of the collet body for a gripping engagement with the external surface of a cylindrical-like workpiece, and the tapered cam surface is formed on the outer circular periphery of the collet body; and,  
       (d) a pair of anchor pins are fixed mounted in a pair of diametrically spaced apart, longitudinal bores in the chuck body with the outer ends of the anchor pins positioned inside of the anchor slots formed in the bottom of the collet body, whereby when the tapered cam surface on the collet body is engaged by the actuator means, the collet body is contracted into a gripping engagement with the external surface of a cylindrical-like workpiece and the anchor pins coact with the anchor slots in the collet body to prevent rotational slippage of the collet body during machining operations on a cylindrical-like workpiece.  
     
     
       20. A collet chuck as defined in claim  1 , wherein: 
       (a) said collet body comprises an outer primary external collet, around which is concentrically and telescopically disposed an inner circular secondary, size reducing external collet;  
       (b) the collet body of said outer primary external collet has a hole formed at an inner arcuate end at each of said plurality of slots in said tapered cam surface, and the axis of each hole is parallel to the workpiece gripping surface;  
       (c) the workpiece gripping surface of the outer primary internal collet body is formed on the inner circular periphery of the primary external collet body for gripping engagement with the outer peripheral surface of the inner circular secondary, size reducing external collet, and the tapered cam surface is formed on the outer circular periphery of the collet body of the outer primary external collet;  
       (d) the inner secondary, size reducing external collet has a collet body with a top end which is planar and parallel to a bottom end thereof which is also planar, and the collet body of the inner circular secondary, size reducing external collet body has an inner periphery surface, and an outer peripheral surface and each of the last mentioned surfaces are vertical, concentric surfaces which are also concentric with the inner peripheral workpiece engaging surface of the outer primary external collet body; and,  
       (e) the inner circular secondary, size reducing external collet body is provided with a plurality of slots which each extend radially inward from the outer peripheral surface thereof and terminate at an inner end with a hole, and the inner circular secondary, size reducing external collet body has a radial opening formed therethrough, whereby when the tapered cam surface on the collet body of the outer primary external collet is engaged by the actuator means, the outer primary external collet and the inner circular secondary, size reducing external collet are contracted into a gripping engagement with the external surface of a cylindrical-like workpiece.  
     
     
       21. The improvement of claim  1 , wherein the collet body further includes an annular base including the workpiece gripping surface and a plurality of radial arms appended to the annular base and arranged to extend in radial directions away from the workpiece gripping surface and each pair of adjacent radial arms cooperate to define one of the circumferentially spaced-apart slots therebetween.  
     
     
       22. The improvement of claim  21 , wherein each radial arm includes a root appended to the annular base and a distal tip arranged to lie in spaced-apart relation to the annular base and the distal tips of the radial arms cooperate to define the cam surface.  
     
     
       23. The improvement of claim  22 , wherein the collet body further includes a plurality of internal end walls and each internal end wall is arranged to define a boundary of one of the circumferentially spaced-apart slots and lie in a position between the workpiece gripping and cam surfaces.  
     
     
       24. The improvement of claim  21 , wherein each pair of adjacent radial arms is configured to define a pair of spaced-apart flat slot surfaces and an arcuate slot surface interconnecting the pair of spaced-apart flat slot surfaces and the flat slot and arcuate slot surfaces cooperate to provide the slot defined between said the pair of adjacent radial arms with a keyhole shape in cross-section.  
     
     
       25. The improvement of claim  24 , wherein each radial arm includes a root appended to the annular base and a distal tip arranged to lie in spaced-apart relation to the annular base and the distal tips of the radial arms cooperate to define the cam surface.  
     
     
       26. The improvement of claim  1 , wherein the collet body includes a central axis and the cam surface is tapered relative to the central axis.  
     
     
       27. The improvement of claim  1 , wherein the collet body includes a second collet body, the second collet body having a central axis and two peripheral surfaces parallel to the central axis.  
     
     
       28. A collet comprising 
       
         a flexible collet body having a workpiece gripping surface and a cam surface, the collet body being split to include a first end and a second end positioned to lie in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end, the collet body formed to include a plurality of circumferentially spaced slots, each slot having an opening in the cam surface and terminating at a terminus located in the collet body at a location between the workpiece gripping surface and the cam surface, and  
       
       
         a tang coupled to the collet body positioned to lie adjacent the end surfaces to cover the split space.  
       
     
     
       29. The improvement of claim  28 , wherein the collet body includes a second collet body, the second collet body having a central axis and two peripheral surfaces parallel to the central axis.  
     
     
       30. A collet comprising 
       
         a flexible collet body having a workpiece gripping surface and a cam surface, the collet body being split to include a first end and a second end positioned to lie in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end, the collet body formed to include a plurality of circumferentially spaced slots, each slot having an opening in the cam surface and terminating at a terminus located in the collet body at a location between the workpiece gripping surface and the cam surface, and  
       
       
         wherein the flexible collet body is split into a plurality of collet pieces to include a plurality of first and second end surfaces to define a plurality of split spaces.  
       
     
     
       31. The collet of claim  30  further comprising a plurality of seals positioned to lie in the split spaces.  
     
     
       32. A chuck for holding a workpiece, the chuck comprising 
       
         an actuator,  
       
       
         a chuck body, and  
       
       
         a flexible collet positioned to lie on the chuck body, the flexible collet including a collet body having an outer periphery and an inner periphery, the collet body being split to include a first end and a second end positioned to lie in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end, one of the peripheries being adapted to be urged by the actuator to flex the flexible collet so that the other periphery moves into engagement with a workpiece to be held by the chuck, the collet body being formed to include a plurality of circumferentially spaced slots each slot, having an opening in one of the peripheries and terminating at a terminus located at a location between the peripheries, and  
       
       
         a pin positioned to lie adjacent the flexible collet to prevent rotational slippage of the flexible collet relative to the chuck body.  
       
     
     
       33. A chuck for holding a workpiece, the chuck comprising 
       
         an actuator,  
       
       
         a chuck body, and  
       
       
         a flexible collet positioned to lie on the chuck body, the flexible collet including a collet body having an outer periphery and an inner periphery the collet body being split to include a first end and a second end positioned to lie in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end, one of the peripheries being adapted to be urged by the actuator to flex the flexible collet so that the other periphery moves into engagement with a workpiece to be held by the chuck, the collet body being formed to include a plurality of circumferentially spaced slots, each slot having an opening in one of the peripheries and terminating at a terminus located at a location between the peripheries, and  
       
       
         a tang coupled to the collet body and positioned to lie adjacent to the end surfaces to cover the split space.  
       
     
     
       34. The chuck of claim  33 , wherein the collet body is formed to include a notch sized to receive the tang.  
     
     
       35. A chuck for holding a workpiece, the chuck comprising 
       
         an actuator,  
       
       
         a chuck body, and  
       
       
         a flexible collet positioned to lie on the chuck body, the flexible collet including a collet body having an outer periphery and an inner periphery the collet body being split to include a first end and a second end positioned to lie in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end, one of the peripheries being adapted to be urged by the actuator to flex the flexible collet so that the other periphery moves into engagement with a workpiece to be held by the chuck, the collet body being formed to include a plurality of circumferentially spaced slots, each slot having an opening in one of the peripheries and terminating at a terminus located at a location between the peripheries, and  
       
       
         wherein the flexible collet body is split into a plurality of collet pieces to include a plurality of first and second end surfaces to define a plurality of split spaces.  
       
     
     
       36. A chuck for holding a workpiece, the chuck comprising 
       
         an actuator,  
       
       
         a chuck body,  
       
       
         a collet including a collet body formed to include means for circumferentially flexing the collet body to grip a workpiece upon engagement of the collet by the actuator, and  
       
       
         wherein the collet body is formed to include a plurality of split spaces providing a portion of the flexing means.  
       
     
     
       37. In a collet chuck having a chuck body provided with at least one collet seat, a collet positioned on the collet seat, an actuator positioned on the chuck body for engagement with the collet to urge the collet into a gripping engagement with a periphery on a workpiece when the actuator is moved in one direction relative to the collet, the improvement comprising: 
       
         the collet having a flexible collet body having an outer periphery, an inner periphery, and a plurality of circumferentially spaced-apart slots;  
       
       
         the flexible collet body being split to include a first end and a second end positioned in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end;  
       
       
         one of the peripheries having a workpiece gripping surface and the other of the peripheries having a cam surface engageable by the actuator urge the workpiece gripping surface into sliding engagement with the workpiece;  
       
       
         the cam surface being formed to include an inlet opening for each of the plurality of circumferentially spaced-apart slots formed in the flexible collet body, and wherein:  
       
       
         the collet body has a plurality of split spaces formed therein.  
       
     
     
       38. A collet chuck as defined in claim  37  wherein: 
       
         an elastomeric seal is positioned between each of the plurality of split spaces in the collet body.  
       
     
     
       39. In a collet chuck having a chuck body provided with at least one collet seat, a collet positioned on the collet seat, an actuator positioned on the chuck body for engagement with the collet to urge the collet into a gripping engagement with a periphery on a workpiece when the actuator is moved in one direction relative to the collet, the improvement comprising: 
       
         the collet having a flexible collet body having an outer periphery an inner periphery, and a plurality of circumferentially spaced-apart slots;  
       
       
         the flexible collet body being split to include a first end and a second end positioned in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end;  
       
       
         one of the peripheries having a workpiece gripping surface and the other of the peripheries having a cam surface engageable by the actuator urge the workpiece gripping surface into sliding engagement with the workpiece;  
       
       
         the cam surface being formed to include an inlet opening for each of the plurality of circumferentially spaced-apart slots formed in the flexible collet body, and wherein:  
       
       
         a closure tang is mounted on the collet body and extends over the split space.  
       
     
     
       40. A collet chuck as in any of claims  37 ,  38 , or  39 , in which the collet body has a hole formed at an inner end of each of the plurality of slots in the cam surface, and the axis of each hole is parallel to and spaced radially apart from the workpiece gripping surface.  
     
     
       41. A collet chuck as in any of claims  37 ,  38 , or  39 , in which the workpiece gripping surface is formed on the outer periphery of the collet body to grip an internal surface of a workpiece, and the cam surface is formed on the inner periphery of the collet body.  
     
     
       42. A collet as in any of claims  37 ,  38 , or  39 , in which the workpiece gripping surface is formed on the inner periphery of the collet body to grip an external surface of a workpiece and the cam surface is formed on the outer periphery of the collet body.  
     
     
       43. In a collet chuck having a chuck body provided with at least one collet seat, a collet positioned on the collet seat, an actuator positioned on the chuck body for engagement with the collet to urge the collet into a gripping engagement with a periphery on a workpiece when the actuator is moved in one direction relative to the collet, the improvement comprising: 
       
         the collet having a flexible collet body having an outer periphery, an inner periphery, and a plurality of circumferentially spaced-apart slots;  
       
       
         the flexible collet body being split to include a first end and a second end positioned in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end;  
       
       
         one of the peripheries having a workpiece gripping surface and the other of the peripheries having a cam surface engageable by the actuator urge the workpiece gripping surface into sliding engagement with the workpiece;  
       
       
         the cam surface being formed to include an inlet opening for each of the plurality of circumferentially spaced-apart slots formed in the flexible collet body, and wherein:  
       
       
         the collet body has a top end and a bottom end, and a pair of diametrically opposite disposed split spaces formed therethrough, and a pair of diametrically opposite disposed anchor slots formed in the bottom end of the collet body on a diametrical axis perpendicular to a diametrical axis of the pair of split spaces;  
       
       
         wherein the workpiece gripping surface is formed on the outer periphery of the collet body for a gripping engagement with the internal surface of a workpiece, and the cam surface is formed on the inner periphery of the collet body; and  
       
       
         a pair of anchor pins are fixedly mounted in a pair of diametrically spaced apart, longitudinal bores in the chuck body with the outer ends of the anchor pins positioned inside of the anchor slots formed in the bottom of the collet body, whereby when the cam surface on the collet body is engaged by the actuator, the collet body is expanded into a gripping engagement with the internal surface of a workpiece and the anchor pins coact with the anchor slots in the collet body to prevent rotational slippage of the collet body during machining operations on a workpiece.  
       
     
     
       44. In a collet chuck having a chuck body provided with at least one collet seat, a collet positioned on the collet seat, an actuator positioned on the chuck body for engagement with the collet to urge the collet into a gripping engagement with a periphery on a workpiece when the actuator is moved in one direction relative to the collet, the improvement comprising: 
       
         the collet having a flexible collet body having an outer periphery, an inner periphery, and a plurality of circumferentially spaced-apart slots;  
       
       
         the flexible collet body being split to include a first end and a second end positioned in spaced-apart relation to the first end to define a split space therebetween to permit relative movement of the second end toward and away from the first end;  
       
       
         one of the peripheries having a workpiece gripping surface and the other of the peripheries having a cam surface engageable by the actuator urge the workpiece gripping surface into sliding engagement with the workpiece;  
       
       
         the cam surface being formed to include an inlet opening for each of the plurality of circumferentially spaced-apart slots formed in the flexible collet body; and  
       
       
         wherein the collet body has a top end and a bottom end and a pair of diametrically opposite disposed split spaces formed therethrough, and a pair of diametrically opposite disposed anchor slots formed in the bottom end of the collet body on a diametrically axis perpendicular to a diametrical axis of the pair of split spaces.