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.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of art to which this invention pertains may be generally located in the class of devices relating to workpiece holding collets. Class 279 Chucks or Sockets, United States Patent Office Classification, appears to be the applicable general area of art to which the subject matter similar to this invention has been classified in the past.

2. Description of the Prior Art

This invention relates to collet mechanisms used in the machining, inspection and grinding industry, where high accuracy workpiece holding devices are required. U.S. Pat. Nos. 3,434,730 and 4,432,559 are illustrative of the prior art collet mechanisms which employ a plurality of flexible fingers mounted on a support sleeve, and which flexible fingers are adapted to be laterally spaced apart and around the outer periphery of a cylindrical workpiece. The prior art collet fingers are adapted to be cammed or compressed radially inward, into gripping engagement with the peripheral surface of a workpiece. A disadvantage of the prior art collet mechanisms employing flexible gripping fingers is that they do not provide a complete 360 degree gripping engagement with the circumference of a cylindrical workpiece. The lack of a 360 degree gripping engagement ability of the prior art collet mechanisms limits the use thereof for gripping a thin walled tubular workpiece close to an end thereof, without causing deflection of the workpiece. Other disadvantages of the prior art collet mechanisms that employ finger members, that are radially expanded and contracted, is that they are inefficient relative to concentricity and repeatability functions for gripping a workpiece, they are true at only one size, and the collet fingers have very minimal travel radially inward, as for example, seven or eight thousandths of an inch.

SUMMARY OF THE INVENTION

The present invention solves the aforedescribed problems of the prior art collet mechanisms by providing a circular collet structure that incorporates a 360 degree gripping engagement with a workpiece with no collet finger gripping action. The circular collet structure allows the holding of a thin wall workpiece with no distortion of the workpiece. The circular collet is constructed and arranged to hold workpieces with as little as 0.050 inch gripping surface with no deflection, which function is not achievable with the prior art collet mechanisms that employ finger action. The circular collet of the present invention provides efficient contraction and expansion during a workpiece gripping operation, with optimum concentricity and repeatability for all sizes of workpieces.

The collet of the present invention comprises a circular collet which is constructed and arranged for operation with a workpiece chuck. The circular collet is operable for contraction and expansion movements into a 360 degree gripping engagement with a cylindrical workpiece surface. The circular collet may be constructed for internal gripping of a workpiece, or for an external gripping of a workpiece. The expansion and contraction of the flexible circular collet is carried out by an actuator means incorporated in a workpiece chuck. The circular collet may be used for single, or plural workpiece gripping actions. The circular collet may be constructed and arranged for gripping engagement with an internal periphery or an external of a workpiece. The flexible circular collet may be provided for internal workpiece gripping actions with an outer periphery shaped in accordance with the internal workpiece surface which is to be gripped, and with an inner sloping cam surface for engagement by an actuator means to expand the collet into an internal workpiece gripping operation. Alternatively, the collet may be provided for external workpiece gripping actions with an inner periphery shaped in accordance with the external workpiece surface which is to be gripped, and with an external sloping cam surface for engagement by an actuator means to contract the collet into an external workpiece gripping operation. The collet of the present invention is contracted or expanded in a rotary movement that effects a peripheral sliding engagement with a workpiece as compared to the flexible fingers of prior art collet mechanisms which are contracted in straight radial line movements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a preloaded, expanded one-piece circular internal collet made in accordance with the principles of the present invention, and which is constructed and arranged for internal workpiece holding operations.

FIG. 2 is an elevation section view of the internal collet illustrated in FIG. 1, taken along the line 2--2 thereof, and looking in the direction of the arrows.

FIG. 3 is a fragmentary, enlarged view of a portion of the internal collet illustrated in FIG. 1, taken within the circle marked by the numeral "3" in FIG. 1, and showing a split in the collet body, and an integral split closure tang.

FIG. 4 is a longitudinal section view of a workpiece chuck provided with an internal collet as illustrated in FIGS. 1 and 2, and showing the internal collet in a retracted position, prior to being expanded outward toward an internal bore in a workpiece for an internal gripping engagement therewith.

FIG. 5 is a longitudinal section view of a workpiece chuck which is identical to the workpiece chuck shown in FIG. 4, but showing only a portion thereof in an enlarged condition, and with the internal collet in a position fully expanded outward into an internal gripping engagement with an internal bore in a workpiece.

FIG. 6 is a longitudinal section view of a workpiece chuck provided with a pair of independently operable dual action internal collets, of the type shown in FIGS. 1 and 2, and in positions fully expanded outward into gripping engagement with a stepped axial bore in a workpiece.

FIG. 7 is a longitudinal section view of a workpiece chuck, showing a pair of independently operable dual action internal collets, of the type illustrated in FIGS. 1 and 2, and showing the collets in a position partially expanded outward, for an internal gripping engagement with a cylindrical bore of a workpiece, and wherein each of the two collets have a separate ram system, with compression spring return means.

FIG. 8 is a longitudinal section view of a workpiece chuck provided with a pair of independently operable dual action internal collets of the type illustrated in FIG. 7, and wherein the outer periphery of each of the collets is ground to a different taper, for mating with and gripping an internal tapered surface of a tapered axial bore in a workpiece.

FIG. 9 is a top view of an unloaded, released one-piece circular external collet made in accordance with the principles of the present invention, and which is constructed and arranged for exterior workpiece holding operations.

FIG. 10 is an elevation section view of the external collet illustrated in FIG. 9, taken along the line 10--10 thereof, and looking in the direction of the arrows.

FIG. 11 is a fragmentary, enlarged view of a portion of the external collet illustrated in FIG. 9, taken within the circle marked by the numeral "11" in FIG. 9, and showing a split in the collet body, and an integral split closure tang.

FIG. 12 is a longitudinal section view of a workpiece chuck provided with an external collet as illustrated in FIGS. 9 and 10, and showing the external collet in a released position before being contracted toward the periphery of a workpiece, for an external gripping engagement therewith.

FIG. 13 is a longitudinal section view of a workpiece chuck which is identical to the workpiece chuck shown in FIG. 12, but showing only a portion thereof in an enlarged condition, and showing the external collet of FIG. 13 in a position fully contracted inward into an external gripping engagement with the periphery of a cylindrical workpiece.

FIG. 14 is a longitudinal section view of a workpiece chuck, showing a pair of independently operable dual action collets of the type illustrated in FIGS. 9 and 10, and showing the collets in a position partially contracted inward for an external gripping engagement with the periphery of a cylindrical workpiece, and wherein each of the collets has a separate ram system, with compression spring return means.

FIG. 15 is a longitudinal section view of a workpiece chuck provided with a pair of independently operable dual action collets of the type illustrated in FIGS. 9 and 10, and showing the collets in a position partially contracted inward, wherein the inner periphery of each of the collets is ground to a different taper, for mating with and gripping an external surface of a workpiece having a longitudinally tapered periphery.

FIG. 16 is a longitudinal section view of a multiple diameter workpiece chuck provided with a plurality of multiple action external collets, of the type illustrated in FIGS. 9 and 10, for gripping engagement with the periphery of a stepped diameter workpiece and wherein the external collets are actuated independently to provide positive squaring of the workpiece in the chuck, and compensate for workpiece diameter variations, and showing the external collets in released positions.

FIG. 17 is a fragmentary, longitudinal section view of a workpiece chuck provided with a pair of dual action external collets, of the type illustrated in FIGS. 9 and 10, and the external collets are mounted with their bottoms adjacent each other, and a ram contracts the external collets inwardly, to provide a positive squaring of a workpiece in the chuck, and to move the external collets into an external gripping engagement with the periphery of a cylindrical workpiece.

FIG. 18 is a fragmentary, longitudinal section view of a workpiece chuck provided with a pair of dual action internal collets, of the type illustrated in FIGS. 1 and 2, and the internal collets are mounted with their bottoms adjacent each other, and a ram expands the internal collets outwardly, to provide a positive squaring of a workpiece in the chuck, and to move the internal collets into an internal gripping engagement with a cylindrical bore in a workpiece.

FIG. 19 is a top view of a one-piece circular external collet which is constructed the same as the external collet shown in FIGS. 9 and 10, but which is not provided with an integral split closure tang.

FIG. 20 is an elevation section view of the external collet illustrated in FIG. 19, taken along the line 20--20 thereof, and looking in the direction of the arrows.

FIG. 21 is a fragmentary, enlarged view of a portion of the external collet illustrated in FIG. 19, taken within the circle marked by the numeral "21" in FIG. 19, and showing the split in the external collet body but which is not provided with an integral split closure tang.

FIG. 22 is a top view of a one-piece circular internal collet which is constructed the same as the internal collet shown in FIGS. 1 and 2, but which is not provided with an integral split closure tang.

FIG. 23 is an elevation section view of the internal collet illustrated in FIG. 22, taken along the line 23--23 thereof, and looking in the direction of the arrows.

FIG. 24 is a fragmentary, enlarged view of a portion of the internal collet illustrated in FIG. 22, taken within the circle marked by the numeral "24" in FIG. 22, and showing the split in the collet body, but which is not provided with an integral split closure tang.

FIG. 25 is a top view of a one-piece circular external collet which is constructed the same as the external collet shown in FIGS. 19 and 20, and which is provided with a rubber seal positioned in the split in the body of the external collet to prevent dirt from entering into the interior of the collet body and contaminating the actuating surface of the external collet.

FIG. 26 is an elevation section view of the external collet illustrated in FIG. 25, taken along the line 26--26 thereof, and looking in the direction of the arrows.

FIG. 27 is a fragmentary, enlarged view of a portion of the external collet illustrated in FIG. 25, taken within the circle marked by the numeral "27" in FIG. 25, and showing the rubber seal positioned in the split in the external collet body.

FIG. 28 is a top view of a one-piece circular internal collet which is constructed the same as the internal collet shown in FIGS. 22 and 23, and which is provided with a split in the collet body, and a rubber seal positioned in the split to prevent dirt from contaminating the actuating surfaces of the internal collet by passage of dirt outwardly through the split.

FIG. 29 is an elevation section view of the internal collet illustrated in FIG. 28, taken along the line 29--29 thereof, and looking in the direction of the arrows.

FIG. 30 is a fragmentary, enlarged view of a portion of the internal collet illustrated in FIG. 28, taken within the circle marked by the numeral "30" in FIG. 28, and showing the split in the internal collet body in which is positioned a rubber seal.

FIG. 31 is a top view of a two-piece circular external collet which is constructed the same as the external collet shown in FIGS. 9 and 10, but which is provided with a pair of splits in the external collet body which are disposed diametrically opposite each other, and which splits are not provided with integral split closure tangs.

FIG. 32 is an elevation section view of the external collet illustrated in FIG. 31, taken along the line 32--32 thereof, and looking in the direction of the arrows.

FIG. 33 is a top plan view of a two-piece circular internal collet which is constructed the same as the internal collet shown in FIGS. 1 and 2, but which is provided with a pair of splits in the internal collet body which are disposed diametrically opposite each other, and which splits are not provided with an integral split closure tang.

FIG. 34 is an elevation section view of the internal collet illustrated in FIG. 33, taken along the line 34--34 thereof, and looking in the direction of the arrows.

FIG. 35 is a top view of a two-piece circular external collet which is constructed the same as the external collet shown in FIGS. 9 and 10, but which is provided with a pair of splits in the external collet body which are disposed diametrically opposite each other, and in each of which splits is mounted a rubber seal to prevent dirt from passing through the splits into the external collet, and prevent contamination of the actuating surface of the external collet.

FIG. 36 is an elevation section view of the external collet illustrated in FIG. 35, taken along the line 36--36 thereof, and looking in the direction of the arrows.

FIG. 37 is a top view of a two-piece circular internal collet which is constructed the same as the internal collet shown in FIGS. 1 and 2, but which is provided with a pair of splits in the internal collet body which are disposed diametrically opposite each other, and in each of which is positioned a rubber seal to prevent dirt from passing through the splits from the interior of the internal collet and contaminating the actuating surfaces of the collet body.

FIG. 38 is an elevation section view of the internal collet illustrated in FIG. 37, taken along the line 38--38 thereof, and looking in the direction of the arrows.

FIG. 39 is a top view of a one-piece circular external collet which is constructed the same as the external collet shown in FIGS. 9 and 10, and wherein the external collet body is provided with U-shaped slots around the periphery thereof, to provide minimal contraction of the external collet during use thereof.

FIG. 40 is an elevation section view of the external collet illustrated in FIG. 39, taken along the line 40--40 thereof, looking in the direction of the arrows.

FIG. 41 is a fragmentary, enlarged view of a portion of the external collet illustrated in FIG. 39 taken within the circle marked by the numeral "41" in FIG. 39.

FIG. 42 is a top view of a one-piece circular internal collet which is constructed the same as the internal collet shown in FIGS. 1 and 2, and wherein the internal collet body is provided with U-shaped slots around the internal periphery thereof, to provide minimal expansion of the internal collet during use thereof.

FIG. 43 is an elevation section view of the internal collet illustrated in FIG. 42, taken along the line 43--43 thereof, and looking in the direction of the arrows.

FIG. 44 is a fragmentary, enlarged view of a portion of the internal collet illustrated in FIG. 42, taken within the circle marked by the numeral "44" in FIG. 42.

FIG. 45 is a top view of a two-piece circular external collet which is constructed the same as the external collet shown in FIGS. 9 and 10, but which is provided with a pair of diametrically opposite disposed splits in the external collet body, and which splits are not covered by integral split closure tangs, and wherein the external collet body is further provided with a pair of diametrically opposite disposed anchor slots in the bottom end of the external collet body, on a diametrical axis perpendicular to the diametrical axis of the pair of splits, and said anchor slots being adapted for the reception of anchor pins to prevent rotational slippage of the collet during heavy machining or grinding operations on a workpiece.

FIG. 46 is an elevation section view of the external collet illustrated in FIG. 45, taken along the line 46--46 thereof, and looking in the direction of the arrows.

FIG. 47 is a fragmentary, longitudinal section view of a workpiece chuck as shown in FIG. 12 and provided with an external collet as illustrated in FIGS. 45 and 46, and wherein the external collet is in a position fully contracted into a gripping engagement with a workpiece, and showing a pair of anchor pins positioned in the anchor slots formed in the bottom end of the external collet body.

FIG. 48 is a top view of a two-piece circular internal collet which is constructed the same as the internal collet shown in FIGS. 1 and 2, but which is provided with a pair of diametrically opposite disposed splits in the internal collet body, and which splits are not covered by integral split closure tangs, and wherein the internal collet body is further provided with a pair of diametrically opposite disposed anchor slots in the bottom end of the internal collet body on a diametrical axis perpendicular to a diametrical axis of the pair of splits, and said anchor slots being adapted for the reception of anchor pins to prevent rotational slippage of the collet during heavy machining or grinding operations on a workpiece.

FIG. 49 is an elevation section view of the internal collet illustrated in FIG. 48, taken along the line 49--49 thereof, and looking in the direction of the arrows.

FIG. 50 is a fragmentary, longitudinal section view of a workpiece chuck similar to the chuck shown in FIG. 4, and provided with an internal collet as illustrated in FIGS. 48 and 49, and wherein the internal collet is in a position fully contracted into a gripping engagement with a workpiece, and showing a pair of anchor pins positioned in the anchor slots formed in the bottom end of the internal collet body.

FIG. 51 is a fragmentary, longitudinal section view of a workpiece chuck, which is identical to the workpiece chuck shown in FIG. 12, but showing only a portion thereof, in an enlarged condition, and with an outer primary external collet which is constructed the same as the external collet shown in FIGS. 9 and 10, and within which is concentrically and telescopically disposed an inner secondary, size reducing external collet, and further wherein the two collets are in a position fully contracted, with the inner secondary external collet in an external gripping engagement with the periphery of a cylindrical workpiece.

FIG. 52 is a top view of the combined structure of the outer primary external collet and the size reducing inner secondary external collet illustrated in FIG. 51, taken along the line 52--52 thereof, and looking in the direction of the arrows.

FIG. 53 is a fragmentary, longitudinal section view workpiece chuck, which is similar to the workpiece chuck shown in FIG. 4, but showing only a portion thereof, in an enlarged condition, and with an inner primary internal collet which is constructed the same as the internal collet shown in FIGS. 1 and 2, and around which is concentrically and telescopically disposed an outer secondary, size enlarging internal collet, and further wherein the two collets are in a position fully expanded, with the outer secondary internal collet in an internal gripping engagement with the internal bore in a cylindrical workpiece.

FIG. 54 is a top view of the combined structure of the inner primary internal collet and the size reducing outer secondary internal collet illustrated in FIG. 51, taken along the line 54--54 thereof, and looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and in particular to FIGS. 1 and 2, the numeral 10 generally designates the ring shaped or circular body of an internal collet, made in accordance with the principles of the present invention, and which is constructed and arranged for internal holding actions on a workpiece. The numeral 11 designates the upper end of the circular internal collet body 10 and the numeral 12 designates the bottom end thereof. The numeral 13 designates the cylindrical outer workpiece gripping surface of the collet. The collet body 10 has a circular inner periphery 14 as shown in FIG. 1. The ring shaped collet body 10 is provided with a downwardly tapered or sloping inner cam face 15.

As best seen in FIG. 3, the internal collet body 10 is provided with a plurality of radially disposed slots 16 which extend radially outward from the inner circular periphery 14 of the collet body to communication with a vertical hole 17 which is formed vertically through the internal collet body 10. The radial slots 16 divide the inner portion of the internal collet body 10 into a plurality of inwardly extended radial arms 18. As best seen in FIG. 3, the internal collet body 10 is provided with first and second ends 8,9 cooperating to define a split or openingsplits or openings split spaces 19g. The splits or openings slit spaces 19g are not provided with an external integral split closure tang, such as the closure tang 150 shown in the collet body 10 in FIG. 3. The provision of a pair of splits or openings split spaces 19g provides an internal collet which is constructed to allow additional flexibility for greater contraction movement of the collet when the collet moves into a gripping engagement with the internal surface of a cylindrical workpiece.

As shown in FIG. 48 the internal collet body 10g is provided with a pair of diametrically opposite disposed anchor slots 368 in the bottom end (FIG. 49) of the internal collet body 10g. The anchor slots 368 extend radially outward from the inner periphery 14g of the collet body 10g and terminate at a round shoulder 369 (FIG. 48). The anchor slots 368 are disposed on a diametrical axis perpendicular to the diametrical axis of the pair of splits or openings split spaces 19g.

As shown in FIG. 50, the collet body 10g is adapted to be used in a workpiece chuck generally designated by the numeral 373. The workpiece chuck 373 comprises a cylindrical chuck body 374 which is provided on the front end thereof with a transverse shoulder 375. The workpiece chuck 373 includes a centrally mounted, fixed solid cylindrical member 376 which is fixedly mounted within a cylindrical bore 377 in the chuck body 374. Integrally formed on the outer end of the fixed solid cylindrical member 376 is a transverse, annular flange 372. An annular, tubular fluid piston rod 379 is slidably mounted between the cylindrical bore 377 in the chuck body 374 and the cylindrical outer periphery 380 of the fixed solid cylindrical member 376. Integrally formed on the outer end of the fluid piston rod 379 is a collet actuator member 381 which is provided on the outer periphery thereof with a forward diverging, angled cam face 382. A suitable O-ring seal 383 is operatively mounted in a groove formed around the outer periphery 380 of the fixed solid cylindrical member 376 and it sealingly engages the inner cylindrical periphery 378 of the fluid piston rod 379 and integral collet actuator member 381.

As shown in FIG. 50, the collet body 10g is adapted to be used in the workpiece chuck 373 in an operative position disposed around the outer peripheral cam face 382 of the collet actuator member 381, with the bottom end 12g seated on the front end 375 of the chuck body 374, and the top end 11g seated against the inner transverse annular wall 384 formed on the inside of the annular flange 372 on the solid cylindrical member 376. A pair of anchor pins 370 are fixedly mounted in a pair of diametrically spaced apart, longitudinal bores 371 in the chuck body 374. The outer ends of the anchor pins 370 are positioned inside of the anchor slots 368 formed in the bottom end 12g of the collet body 10g. The fluid piston rod 379 would be operated into the operative position shown in FIG. 50 by a suitable fluid piston and supporting structure of the type shown in FIGS. 12 and 13. The collet body 10g is shown in an expanded workpiece engaging position with the outer periphery 13g in gripping engagement with the inner periphery 385 of a workpiece 386. The fluid operated piston 379 would be returned, to the right as viewed in FIG. 50, to an inoperative position, with the outer end of the collet actuator member 381 seated against the annular transverse wall 384 on the annular flange 377, by suitable compression return springs, as is employed in the workpiece chuck 153 shown in FIGS. 12 and 13. The anchor pins 370 coact with the anchor slots 368 to prevent rotational slippage of the collet body 10g during machining or grinding operations on the workpiece 386.

FIG. 51 is a fragmentary, longitudinal section view of a workpiece chuck designated by the numeral 153h, which is identical to the workpiece chuck shown in FIG. 12, but showing only a portion thereof, in an enlarged condition. The parts of the workpiece chuck 153h which are the same as the parts of the workpiece chuck shown in FIG. 12 have been marked with the same reference numerals followed by the small letter "h".

Operatively mounted on the workpiece chuck 153h is an outer primary external collet which is constructed the same the external collet shown in FIGS. 9 and 10, and it has a collet body marked by the numeral 140h. The parts of the outer primary external collet shown in FIG. 51 have been marked with the same reference numerals as used in the description of the external collet shown in FIGS. 9 and 10, followed by the small letter "h". An inner secondary, size reducing external collet, which is constructed substantially like the external collet shown in FIGS. 9 and 10, is concentrically and telescopically disposed within the outer primary external collet and it has a collet body marked by the numeral 140h'. The parts of the inner secondary, size reducing external collet have been marked with the same reference numerals as used in the description of the external collet shown in FIGS. 9 and 10, followed by the small letter "h'". The two collet bodies 140h and 140h' are shown in FIG. 51 in a position fully contracted, with the inner secondary, size reducing external collet body 140h' in an external gripping engagement with the periphery of a cylindrical workpiece 174h.

FIG. 52 is a top view of the combined collet structure, of the outer primary external collet body 140h and the inner secondary, size reducing external collet body 140h' illustrated in FIG. 51, taken along the line 52--52 thereof, and looking in the direction of the arrows.

The inner periphery surface 143h' and the outer peripheral surface 144h' of the collet body 140h' of the inner secondary, size reducing external collet are each machined with vertical, concentric surfaces which are also concentric with the vertical inner peripheral surface 143h of the outer primary external collet body 140h. The inner secondary, size reducing external collet body 140h' has a top end 141h' which is planar and parallel with the bottom end planar surface 142h' (FIG. 51), and it is provided with a plurality of radial slots 146h' which extend inward from the outer periphery 144h' and terminate at their inner ends with the holes 147h'. The parts of the inner secondary, size reducing external collet body 140h' which function in the same manner as the parts of the outer primary external collet body 140h have been marked with the same reference numerals followed by the small letter "h". The combination of the outer primary external collet body 140h and the inner secondary, size reducing external collet body 140h' would be employed to permit a workpiece chuck to be used for a plurality of cylindrical workpieces having difference size external diameters.

FIG. 53 is a fragmentary, longitudinal section view of a workpiece chuck designated by the numeral 25k which is similar to the workpiece chuck 25 shown in FIG. 4, but showing only a portion thereof, in an enlarged condition. The parts of the workpiece chuck 25k which are the same as the parts of the workpiece chuck 25 shown in FIG. 4 have been marked with the same reference numerals followed by the small letter "k".

Operatively mounted on the workpiece chuck 25k is an inner primary internal collet which is constructed the same as the internal collet shown in FIGS. 1 and 2, and it has a collet body marked by the numeral 10k. The parts of the inner primary internal collet shown in FIG. 53 have been marked with the same reference numerals as used in the description of the internal collet shown in FIGS. 1 and 2, followed by the small letter "k". An outer secondary, size enlarging internal collet, which is constructed substantially like the internal collet shown in FIGS. 1 and 2, is concentrically and telescopically disposed around the inner primary internal collet and it has a collet body marked by the numeral 10k'. The parts of the outer secondary, size enlarging internal collet have been marked with the same reference numerals as used in the description of the internal collet shown in FIGS. 1 and 2, followed by the small letter "k". The two collet bodies 10k and 10k' are shown in FIG. 53 in a position fully expanded, with the outer secondary, size enlarging internal collet body 10k' in an internal gripping engagement with the inner periphery of a cylindrical workpiece 67k.

FIG. 54 is a top view of the combined expanded collet structure, of the inner primary internal collet body 10k and the outer secondary, internal collet body 10k' illustrated in FIG. 53, taken along the line 54--54 thereof, and looking in the direction of the arrows.

The outer peripheral surface 13k' and the inner peripheral surface 14k' of the collet body 10k', of the outer secondary, size enlarging internal collet are each machined with vertical, concentric surfaces, which are also concentric with the vertical outer peripheral surface 13k of the inner primary internal collet body 10k. The outer secondary, size enlarging internal collet body 10k' as a top end 11k' which is planar and parallel to the bottom end planar surface 12k' thereof (FIG. 53), and it is provided with a plurality of radial slots 16k' which each extend radially outward from the inner peripheral surface 14k' and terminate at an outer end with a hole 17k'. The parts of the outer secondary, size enlarging internal collet body 10k' which function in the same manner as the parts of the inner primary internal collet body 10k have been marked with the same reference numerals followed by the small "k'". The combination of the inner primary internal collet body 10k and the outer secondary, size enlarging internal collet body 10k' would be employed to permit a workpiece chuck to be used for a plurality of cylindrical workpieces having different size internal diameters.

It will be understood that the transverse annular shoulder or collet seat 54 of the workpiece chuck 25, shown in FIG. 4, functions as a positive stop for the internal collet actuator member 57 when it is actuated, to provide for safe use of the chuck 25 by unskilled users of the chuck 25. The positive stop 54 shown in FIG. 4, also functions to eliminate over expansion or contraction of a collet, for safe use by unskilled users of workpiece chucks employing a collet made in accordance with the present invention. The corresponding positive stop structures employed in the workpiece chucks shown in the other Figures of the application function the same manner as the positive stop 54.

The tapered outer periphery 58 on the collet actuator member 57 is formed at an angle commensurate with the angle of the cam surface 15 on the inner periphery of the collet body 10 shown in FIG. 4. The same relation would exist between the cam surfaces on both the internal and external collet bodies and the tapered peripheries on the collet actuator members for the collets shown in the other Figures of the application.

FIGS. 32 and 35 show external collets split into two parts to allow greater contraction. FIGS. 33 and 34 show two internal collets split into two parts to allow greater expansion. It will be understood that the external and internal collets made in accordance with the invention may be split into more than two parts to allow for greater expansion and contraction, as desired.

The following is an explanation of the procedure for making an internal collet as illustrated in FIGS. 1, 2 and 3. As previously stated herein, the collet body 10 may be made from a suitably spring steel hardened to a 44-46 Rockwell C scale hardness. An optimum spring steel is an S.A.E. spring steel No 6150. A cylindrical workpiece made of the last mentioned spring steel would be mounted in a suitable machine, such as a lathe, and the outer end of the workpiece would be cut off to provide a collet body thickness gripping area of a desired size, as for example, three-eights of an inch, plus a few thousandths of an inch additional stock for a final grinding finish on the top and bottom end faces of the collet body, as on the top and bottom end faces 11 and 12 of, respectively, of the collet body 10 shown in FIG. 2.

Assuming that the selected diameter of the outer periphery 11 of the collet body 10 is 2.5 inches and the selected diameter of the inner periphery 14 of the collet body 10 is 2 inches, an axial bore of 2 inches is then machined through the workpiece. The angle 22 for the inner cam face 15 is then machined to an angle selected from a range of from 1 degree to 45 degrees, depending on the holding force required for the collet, in accordance with the requirement of the ultimate user of the collet, and calculated as set forth hereinbefore to determine the angle 22. The plurality of vertical holes 17 are then radially located and drilled in accordance with the following formula. The holes 17 are drilled to a selective size of 3/32 inch diameter, and they are located on a 1.166 inch radius. The radius location for the 3/32 inch diameter holes is determined as follows. The collet body outer diameter of 2.5 inches has subtracted therefrom the inner diameter of 2.0 inches which equals 0.5 inches. The 0.5 inches is divided by 2, which equals 0.25 inches, the thickness of the body 10 at the lower end 12, between the inner periphery 14 and the outer periphery 13. The axis of each of the holes 17 is to be located outward from the inner periphery 14 at a point 2/3 of said thickness of the body 10. Accordingly the 0.25 inches is multiplied by 2/3 which equals 0.166 inches. The inner diameter radius is 1 inch, and it is added to the 0.166 inches to give a resultant 1.166 inches radius for locating the 3/32 inch diameter holes about the axis of the collet body 10.

The 3/32 diameter holes are then drilled at said 1.166 inches radius location around the axis of the collet body 10, at equally spaced apart circumferential points which are determined as follows.

The inner diameter radius of 1 inch is subtracted from the 3/32 inch diameter hole location radius of 1.166 inches, which results in a figure of 0.166 inches. One half of the dimension of a 3/32 inch diameter hole is 0.046 inches and it is subtracted from said 0.166 inches which equals 0.120 inches, and that is the web thickness from the outer periphery of a 3/32 inch diameter hole to the outer periphery 13 of the collet body 10. The diameter of a 3/32 inch hole, namely 0.093 inches, is added to said web thickness of 0.120 inches to provide a resultant dimension of 0.213 inches for the radial location spacing of the 3/32 inch diameter holes from the inner periphery 14.

The number of 3/32 inch diameter holes 17 is determined by multiplying the location radius of 1.166 for said holes by two, which equals 2.332 inches. The 2.332 inches is multiplied by 3.1416 (PI) which equals 7.326 inches, which is the circumference of the center points of the 3/32 inch diameter holes 17. The circumference of 7.326 inches is divided by 0.213 inches, which is the radial location spacing for the 3/32 inch diameter holes 17, which results in 34 holes. The angular spacing of the 3/32 inch holes 17 is determined by dividing 360 degrees by the number of holes 17, namely 34, which results in an angular spacing of 10 degrees for the 34 holes, on the 1.166 inch radius.

The following is an explanation of the procedure for mating an external collet as illustrated in FIGS. 9, 10 and 11. The external collet body 140 would be made from the same type steel as used for the internal collet body 10. The external collet body 140 would be machined from a workpiece in the same manner as described for the internal collet body 10.

Assuming that the selected diameter of the outer periphery 144 of the external collet body 140 is 2.5 inches and the selected diameter of the inner periphery 143 of the external collet body 140 is 2 inches, an axial bore of 2 inches is then machined through the workpiece. The angle 151 for the outer cam face 145 is then machined to an angle selected from a range of from 1 degree to 45 degrees, depending on the holding force required for the collet, in accordance with the requirement of the ultimate user of the collet, and calculated as set forth hereinbefore to determine the angle 151. The plurality of vertical holes 147 are then radially located and drilled in accordance with the following formula. The holes 147 are drilled to a selective size of 3/32 inch diameter, and they are located on a 1.129 inch radius. The radial location for the 3/32 inch diameter holes is determined as follows. The collet body outer diameter of 2.5 inches has subtracted therefrom the inner diameter of 2.0 inches which equals 0.5 inches. The 0.5 inches is divided by which equals 0.25 inches, the thickness of the collet body 140 at the lower end 142, between the inner periphery 143 and the outer periphery 144. The axis of each of the holes 147 is to be located outward from the inner periphery 143 at a point 1/3 of said thickness of the collet body 140. Accordingly the 0.25 inches is multiplied by 1/3 which equals 0.083 inches. The inner diameter radius is 1 inch, and it is added to the 0.083 inches, and to 1/2 of the diameter of the holes 147, namely 0.046 inches, to give a resultant 1.129 inches radial location for the 3/32 inch diameter holes 147 about the axis of the collet body 140.

The 3/32 diameter holes 147 are then drilled at said 1.129 inches radial location around the axis of the collet body 140, at equally spaced apart circumferential points which are determined as follows.

The inner diameter radius of 1 inch is subtracted from the 3/32 inch diameter hole location radius of 1.129 inches, which results in a figure of 0.129 inches. One half of the dimension of a 3/32 inch diameter hole 147 is 0.046 inches and it is subtracted from said 0.129 inches which equals 0.083 inches, and that is the web thickness from the inner periphery of a 3/32 inch diameter hole to the inner periphery 143 of the collet body 140. The diameter of a 3/32 inch hole, namely 0.093 inches, is added to said web thickness of 0.083 inches to provide a resultant dimension of 0.176 inches for the radial location of the 3/32 inch diameter holes 147 from the outer periphery 144.

The number of 3/32 inch diameter holes 147 is determined by multiplying the location radius of 1.129 inches for said holes 147 by two, which equals 2.258 inches. The 2.258 inches is multiplied by 3.1416 (PI) which equals 7.094 inches, which is the circumference of the center points of the 3/32 inch diameter holes 147. The circumference of 7.094 inches is divided by 0.176 inches, which is the radial location spacing for the 3/32 inch diameter holes 147, which results in 40 holes. The angular spacing of the 3/32 inch holes 147 is determined by dividing 360 degrees by the number of holes 147, namely 40, which results in an angular spacing of 9 degrees for the 40 holes, on the 1.129 inch radius.

The slots 16 in the internal collet body 10 illustrated in FIGS. 1, 2 and 3, and the slots 146 in the external collet body 140 illustrated in FIGS. 9, 10 and 11, may be machined to an optimum width of two-thirds of the diameter of the 3/32 holes 17 and 147, respectively. The machining of the slots 16 and 146 may be carried out by a suitable grinding wheel operation or by the use of an electrical discharge machine.

The internal collet body 10f as shown in FIGS. 42, 43 and 44, and the external collet body 140f as shown in FIGS. 39, 40 and 41, would have the slots 16f and 146f, respectively, formed by first locating and drilling holes, such as 3/32 inch diameter holes, in the same manner as described hereinbefore for the internal collet shown in FIGS. 1, 2 and 3, and the external collet shown in FIGS. 9, 10 and 11. The slots 16f and 146f would then be machined by either a grinding wheel or an electrical discharge machine to make the sides of the last mentioned slots tangent to the inner peripheries of the 3/32 holes.

It will be understood that the 3/32 inch diameter size hole was selected as an illustrative example for explaining the making of illustrative internal and external collets in accordance with the invention. However, other size holes could be used, as for example, a 1/16 inch diameter hole size. It will also be understood that internal and external collets made in accordance with the invention will vary in size in accordance to the size of workpieces to be held by a collet.

The term cylindrical workpiece used in the claims is defined as being any cylindrical-like workpiece, whether solid, hollow or tubular, and having an external circular periphery, or an internal circular periphery, or both an external and an internal circular periphery.

Claims

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.