US3735436A

US3735436A - Arrangement for disengaging threading dies in a threading die head

Info

Publication number: US3735436A
Application number: US00261531A
Authority: US
Inventors: G Louys
Original assignee: Georg Fischer AG
Current assignee: Georg Fischer AG
Priority date: 1971-06-14
Filing date: 1972-06-09
Publication date: 1973-05-29
Anticipated expiration: 1990-05-29
Also published as: CH524420A; DE2223831B2; BE784846A; FR2142371A5; AT316262B; GB1332624A; JPS5131714B1; ES403708A1; IT955798B; DE2223831A1

Abstract

For disengageably securing threading dies in the head of a thread-cutting machine or a similar device, axially extending holding bolts are provided in a die carrier for locating the dies in the threading position. The ends of the holding bolts spaced from the dies are secured to a flange displaceably mounted on the die carrier. A slide bushing is in threaded engagement with the flange and extends axially through a bore in the die carrier. A sensing bolt extends through the slide bushing and has a contact surface on one end for contacting a workpiece being threaded. Springs are located in the die carrier for biasing the flange away from the dies. While the workpiece is being threaded, the slide bushing is held against displacement in the axial direction relative to the die carrier, however, when the threading action is completed the sensing bolt is displaced axially and releases the locking action between the slide bushing and the die carrier. As a result, the flange connected to the slide bushing is biased by the spring so that the holding bolts release the dies from the threading position.

Description

O llnited States Patent 91 [111 3,735,436 Louys 1 51 May 29, 1973 1 ARRANGEMENT FOR DISENGAGING 3,580,690 5/1971 McClure ..10/96 R THREADING DIES IN A THREADING DIE HEAD Primary ExaminerCharles W. Lanham Assistant Examiner-E. M. Combs [75] Inventor fi Louys schafihausen Attorney-David Toren, Bernard X. McGeady and let an Leo Stanger [73] Assignee: Georg Fisher Aktiengesellschaft,

Schaffltausen, Switzerland ABSTRACT [22] Filed: June 9, 1972 For disengageably securing threading dies in the head of a thread-cutting machine or a similar device, axially [2]] Appl' 261531 extending holding bolts are provided in a die carrier for locating the dies in the threading position. The [30] Foreign Ap li ti n P i it D ends of the holding bolts spaced from the dies are secured to a flange displaceably mounted on the die June 14, 1971 Switzerland ..8625/71 Garden A Slide bushing is in threaded engagement with the flange and extends axially through a bore in [52] LS. Cl. ..10/96 R, 10/120,408/148 the i Garden A Sensing bolt extends through the [51] "B23g 5/12 slide bushing and has a contact surface on one end for [58] Field Of Search ..10/89 H, 89 P, 94, contacting a workpiece being threaded Springs are 10/95 96 123 located in the die carrier for biasing the flange away 123 S; 279/66 6975; 408/148 153 from the dies. While the workpiece is being threaded, the slide bushing is held against displacement in the [56] References C'ted axial direction-relative t0 the die carrier, however, when the threading action is completed the sensing UNITED STATES PATENTS bolt is displaced axially and releases the locking action 2,130,181 9/1938 Hogg ..10/95 between the slide bushing and the die carrier. As a 2,135,067 11/1938 Breitenstein ..10/95 result, the flange connected to the slide bushing is Breitenstein biased the so that the bolts release 2,471,250 5/1949 Strickland ..10/95 the dies from the threading position. 1 2,746,066 5/1966 Finn et al. ..10/95 16 Claims, 3 Drawing Figures 1 fee, 1 2v v 1 1 A v 8 i 5 26 7 1 f a 0: y A 6 1 1 l T i l 19 1 1 1:1 2t l T 9 7 l 1 I y I 16 l8/ l' I 10 l lla ARRANGEMENT FOR DISENGAGING THREADING DIES IN A THREADING DIE HEAD SUMMARY OF THE INVENTION The present invention is directed to a die head or chuck for disengageably securing threading dies in the threading position and, more particularly, it concerns an arrangement mounted within a die carrier for disengaging the threading dies from the threading position.

In one known threading die head, a setting ring is positioned within and is rotatable relative to a die carrier and holds the threading dies. The setting ring includes a cam, and a compression spring is associated with the cam. The compression spring biases the setting ring into engagement with the contact or abutment surface of a follower and thus'holds the threading dies in the threading position. For determining the length of a thread cut into a pipe or workpiece, a sensing element checks the thread length and whena predetermined length has been reached, it lifts the follower from the cam of the setting ring. When this occurs, the compression spring rotates the setting ring and the dies are lifted out of the threading position.

In this previously known threading die head, a portion of the sensing and release mechanism used in restoring or resetting the threading dies, is arranged in an eccentric and projecting manner on the die carrier. Such an arrangement is dangerous, since it tends to cause injury to personnel asthe threading die head rotates and it is also disadvantageous, because the resetting action can be performed only when the threading die head is at rest.

Another known embodiment of a threading die head includes a setting body for the threading dies in which the positions of the setting body are determined by coupling members. The setting body is biased by a restoring spring which tends to move it into a position in which the threading dies are displaced from the threading position. For actuating the biasing action of the restoring spring, a sensing arrangement is provided to de- When a predetermined length of thread has been cut, the coupling members are released and, due to the biasing action of the restoring spring, the setting body is turned so that the threading dies are displaced from the threading position. To restore the threading die head while tensioning the restoring spring, it is necessary to use a key which is inserted radially into an opening in the setting body. As with the other known embodiment mentioned above, the threading die head can only be restored into the threading position when the arrangement is completely at rest.

Therefore, it is the primary object of the present invention to provide a self-releasing threading die head arrangement which can be returned to the threading position without any danger of accident or injury, even during rotation. Due to this arrangement, accelerated threading is possible.

In accordance with the present invention, a threading die head used in a thread-cutting machine or device has a plurality of disengageable threading dies mounted in a die carrier. The dies are held in the threading position by cams located on the ends of holding bolts which extend through the die carrier. The die carrier has an annular shape and forms an axially extending bore. At the end of the die carrier, spaced from the dies, a flange is positioned about the bore and springs mounted in the termine the length of the thread cut in a workpiece.

die carrier bias the flange away from the dies. A slide bushing is held in threaded engagement with the flange and extends into the bore through the die carrier. Extending through the slide bushing is a sensing bolt and one end of the bolt extends beyond the slide bushing and has a contact surface arranged to contact the end of a workpiece being threaded. During the threading operation, balls fitted into openings in the slide bushing engage in a groove within the die carrier and hold the slide bushing and flange against axial displacement relative to the die carrier. When the threading operation is completed, the sensing bolt is displaced axially and has a groove into which the locking balls in the slide bushing are displaced so that the slide bushing and flange are no longer secured against axial displacement. As a result, the springs in the die carrier bias the flange away from the dies and holding bolts, which are secured to the flange and hold the dies in the threading position, are axially displaced with the flange and release the dies from the threading position.

To limit the axial displacement of the flange and the other parts attached to it, the flange is attached to the die carrier by screws which afford a certain length of axial displacement of the flange.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a longitudinal sectional view of a device embodying the present invention;

FIG. 2 is a partial section of the device shown in FIG. 1; and

FIG. 3 is a partial sectional view of another embodiment of the device shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1 a thread-cutting die head is illustrated which can be mounted in a ratchet wrench or a threadcutting machine. The thread-cutting die head includes an annularly shaped axially extending die support member or carrier 1 having an axially extending bore 12. At one end of the die carrier 1, a plurality of radial grooves 26 are formed in which thread-cutting dies 2 are positioned. At the forward end of the die carrier, that is the end containing the dies 2, an annular plate 17 is detachably secured to the carrier by means of bolts 18 and forms a cover over the ends of the grooves 26.

Each of the threading dies is provided with an obliquely extending holding groove 2' formed into one of its sides and the holding grooves are equidistantly spaced from the axis of the die carrier 1. Complementary shaped holding cams 3 fit into the holding grooves 2' for securing the dies 2 in the threading position. Each holding cam 3 is associated with a holding bolt 4 and extends outwardly'from the end of the holding bolt. The holding bolts are axially movable within a circle of bores'4' formed through the die carrier 1, the circle of the bores is concentrically arranged about the axis of the die carrier. At the opposite end of the holding bolts 4 from the holding cams 3, locking surfaces 27 are provided which engage into corresponding recesses or cutouts in an annular flange 5. The flange 5 is positioned on the rearward end of the die carrier 1 and is arranged concentrically about its axis.

Extending through the flange 5 into the bore 12 in the die carrier 1 is a slide bushing 6 which is in threaded engagement with the flange. The slide bushing 6 is axially movably positionable within the bore 12 so that its threaded engagement with flange can be adjusted.

A sensing bolt 7 extends through the slide bushing 6 from the rearward end toward the forward end of the die carrier. The forward end of the sensing bolt 7 is positioned forwardly of the end of the slide bushing 6 within the bore 12 and has a contact surface 9 at its forward end which contacts the juxtaposed end of a workpiece 8 as the threading operation proceeds. The contact surface has a diameter which is smaller than the root diameter of the thread cut into the workpiece and is larger than the inner diameter of the workpiece when it is of a tubular form. Between the contact surface 9 of the sensing bolt and the forward end of the slide bushing 6, the sensing bolt has a shoulder 9a which projects radially outwardly beyond the radially inner surface of the slide bushing 6. Immediately adjacent the shoulder 9a and extending toward the rearward end of the sensing bolt is an annular groove 10 which has a diameter smaller than the diameter of the inside surface of the slide bushing 6.

Adjacent the forward end of the slide bushing 6, a number of openings 11a each contain a ball 11 which, when the threading dies 2 are in the threading position, seat within a groove 13 extending annularly about the surface of the bore 12. The diameter of the ball is such that it equals the wall thickness dimension of the slide bushing plus the depth 25 of the groove 13. Similarly, the depth 24 of the annular groove 10 in the sensing bolt measured inwardly from the inner surface of the slide bushing is substantially equal to the depth 25 of the groove 13. Accordingly, when the threading die head is in the threading position, the balls 11 are secured within the groove 13 and provide an interengagement between the slide bushing 6 and the die carrier 1 so that the slide bushing is not displaced axially relative to the die carrier.

As can be seen in FIG. 1, the sensing bolt 7 extends rearwardly beyond the rearward end of the slide bushing 6 and a securing ring 19 encircles the rearward end of the sensing bolt for limiting its stroke. Further, a ball and spring device 16 is formed in the lateral surface of the sensing bolt 7 with the ball being biased into a groove or recess in the inner surface of the slide bushing 6 for preventing any accidental displacement of the sensing bolt relative to the slide bushing.

In the flange 5, a safety member extends into locking engagement with the slide bushing 6 to prevent any relative rotation between the flange and the slide bushing when the threaded connection between the two has been established.

In the surface of the die carrier 1 juxtaposed to the face of the flange 5 directed toward the forward end of the die carrier, are a number of bores 21 each containing a spring 14. While one spring could be used, it is preferable to employ a number of such springs. The springs 14 are compressed when the flange is held against the die carrier and the springs bias the flange in the direction outwardly away from the rearward end of the die carrier.

In FIG. 1, one of a number of cams 22 are shown on the outer circumferential surface of the die carrier arranged for engagement within a ratchet wrench or a thread-cutting machine. The cams 22 secure the die carrier to the thread-cutting device in the manner of a bayonet closure so that the threading die head follows the movement of the thread cutting device.

FIG. 1 shows the manner in which the dies 2 are held in the threading position as threads are cut in the surface of the workpiece 8. During the threading operation, the slide bushing 6 secured to the die carrier 1 by the balls 11 extending into the groove 13 holds the flange 5 against the rearward end of the die carrier. With the flange held against the die carrier the holding bolts 4 by means of the cams 3 hold the threading dies 2 in position. When the threading operation is completed, the engagement between the end surface-of the workpiece 8 and the contact surface 9 of the sensing bolt 7 displaces the sensing bolt toward the rearward end of the die carrier until the annular groove 10 in the sensing bolt moves into register in the axial direction with the openings 11a in the slide bushing 6. When the annular groove 10 and the openings are in register, the balls 11 are displaced inwardly so that the slide bushing 6 is no longer held against axial displacement relative to the die carrier. With the slide bushing released, the springs 14 bias the flange outwardly away from the rearward end of the die carrier and the flange in turn pulls the holding bolts 4 and their associated cams 3 from engagement within the grooves 2' of the threading dies 2 so that the threading dies are released from the threading position.

In FIG. 2 a screw 20 is shown extending through a bore 23 in the flange 5 into another bore in the die carrier 1. The head of the screw 20 extends outwardly from the face of the flange and provides a stop surface for limiting the axial displacement of the flange and of the holding bolts 4 when the slide bushing is released from its engagement with the die carrier. While a single screw 20 is shown in FIG. 2, it will be appreciated that it is preferable to provide a number of such screws spaced about the flange.

In FIG. 3 another embodiment of a die carrier 1' is illustrated which includes a screw bushing 28 inserted coaxially into the bore of the die carrier 1'. The screw bushing 28 is inset into the bore of the die carrier from its rearward end. A slide bushing 6' in threaded engagement with an annular flange 5, extends into the bore formed by the screw bushing 28. The screw bushing 28 has a threaded portion 31 in threaded engagement with the bore of the die carrier 1' so that it can be adjusted in the axial direction. This axial adjustment provides a control over the length of the thread to be cut by the device.

The forward end of the screw bushing 28, that is the end spaced from the threaded portion 31, is provided with screw slots 32. A safety device 30 extends through the wall of the die carrier 1' into engagement with the outer surface of the screw bushing 28 for holding the bushing against any undesired or unintentional rotation. Forwardly of the annular groove 10', in the sensing bolt 7', is a packing or washer 29 disposed about the surface of the sensing bolt for preventing the penetration of dirt and other undesired extraneous matter into the bore of the die carrier which affords a guide for the sensing bolt 7'.

ln place of the arrangement shown in FIG. 2, the extent of the axial displacement of the flange 5' in FIG. 3, is provided by an enlarged diameter within the forward interior end of the screw bushing 28 which affords a contact shoulder surface 33 at the point where the inside diameter of the screw bushing is reduced and contacts the outer surface of the slide bushing 6. Adjacent the forward end of the annular groove is a collar 34 which extends radially outwardly so that it projects at least radially outwardly beyond the inner edge of the shoulder surface 33. As can be seen in FIG. 3, the ball locking arrangement is provided between the slide bushing 6 and the screw bushing 28. When the ball lock is released by the axial displacement of the sensing bolt 7 and the ball enters the annular groove 10, the axial displacement of the sensing bolt 7', the slide bushing 6' and the flange 5"are limited by the contacting engagement between the collar 34 on the sensing bolt and the shoulder surface 33 on the screw bushing held within the bore of the die carrier 1.

While specific embodiments of the invention have been shown and described on detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. A threading die head for insertion into a threadcutting machine for cutting threads in a workpiece, said die head including an annularly shaped die carrier having a bore extending axially therethrough, a plurality of disengageable threading dies mounted in said die carrier, holding cams arranged to secure said threading dies in the threading position, and means associated with said cams for releasing said dies from the threading position, wherein the improvement comprises that said die carrier is axially elongated, a plurality of axially movable angularly spaced holding rods extending axially through said die carrier, said means for releasing said die comprises an annular flange located on one end of said die carrier spaced axially from saiddies and having an opening therethrough, means for resiliently biasing said flange in the axial direction away from said dies, means for securing said holding bolts to said flange, a slide bushing positioned within an extending axially through the opening in said flange and the bore in said die carrier, said slide bushing disposed in detachable engagement with. said flange, a sensing bolt arranged coaxially within and extending through said slide bushing, said sensing bolt having a contact surface arranged to engage the workpiece, said sensing bolt having an annular groove formed on its surface'located radially inwardly of the inner surface of said slide bushing, said slide bushing having at least one opening extending through its wall from its outer to its inner surface, a ball positioned within the opening in said slide bushing and having a diameter substantially equal to the wall thickness of said slide bushing and the depth of the annular groove in said sensing bolt, said die carrier having an annular groove formed in the surface of its bore and the annular groove in said die carrier has a depth substantially equal to the depth of the annular groove in said sensing bolt so that said ball can be seated within said annular groove in said die carrier and the opening in said slide bushing, each of said holding bolts at the ends opposite the end secured to said flange having one of said holding cams mounted thereon, so that with said ball positioned within the opening in said slide bushing and in the annular groove in said die carrier said slide bushing is held against axial displacement relative to said die carrier with said dies secured in the threading position by said holding cams and with the annular groove in said sensing bolt displaced axially from said opening in said slide bushing, and when said contact surface of said sensing bolt in engagement with the workpiece displaces said sensing bolt axially within said slide bushing until the annular groove therein is registered opposite the opening in said slide bushing and said ball is displaced inwardly into the annular groove in said sensing bolt affording axial displacement of said slide bushing and flange relative to said die carrier due to said means for resiliently biasing said flange and the axial displacement of said flange effecting the axial withdrawal of said holding cams from said dies for releasing said dies from the threading position.

2. A threading die head, as set forth in claim 1, characterized in that where a tubular workpiece is to be threaded, the outside diameter of the contact surface of said sensing bolt is smaller than the root diameter of the thread to be cut and larger than the inside diameter of the tubular workpiece.

3. A threading die head, as set forth in claim 1, wherein said means for resiliently biasing said flange comprises a plurality of bores formed in said die carrier with the axis of said bores extending in the axial direction of said die carrier, and a spring positioned within each of said bores and contacting said flange so that said springs bias said flange inthe axial direction away from said dies.

4. A threading die head, as set forth in claim 1, wherein said flange and said slide bushing are detachably engaged by a threaded connection therebetween, and means for securing said flange to said slide bushing for preventing relative rotation therebetween.

5. A threading die head, as set forth in claim 4, wherein said means for securing said flange and said sliding bushing against relative rotation comprises a securing device extending through said flange into en gagement with said sliding bushing in the range of the threaded connection therebetween.

6. A threading die head, as set forth in claim 1, wherein a plurality of follower cams mounted on the circumferential periphery of said die carrier and said die cams arranged for engagement within a threadcutting device in the manner of a bayonet closure for securing said threading die head to the thread-cutting device.

7. A threading die head, as set forth in claim 1, wherein said flange having at least one opening therethrough with the axis of said opening in parallel relationship with the axis of the bore in said die carrier, a screw positioned within said bore and extending into engagement with said die carrier, said screw having a head thereon with a diameter greater than the diameter of the opening in said flange and said head disposed in axially spaced relationship from the flange in the threading position of said threading die head so that said head on said screw affords a stop surface for limiting the axial displacement of said flange.

8. A threading die head, as set forth in claim 1, wherein said contact surface is formed on the end surface of said sensing bolt located closer to the end of said die carrier containing said dies.

9. A threading die head, as set forth in claim 1, wherein a bore extending into said sensing bolt transversely of the axis thereof and within the range of said sensing bolt positioned within said slide bushing, aball spring assembly positioned within said bore in said sensing bolt, and the recess formed in the inner surface of said slide bushing opposite the bore in said sensing bolt so that said ball is spring biased into the recess in said slidebushing for preventing accidental axial displacement of said sensing bolt relative to said slide bushing.

10. A threading die head, as set forth in claim 1, wherein said slide bushing having a number of openings therein'and one of said balls located within each of said openings for interconnecting said die carrier and said slide bushing.

11. A threading die head, as set forth in claim 1, wherein a screw bushing is fitted within the bore in said die carrier and is in axially adjustable threaded engagement with said die carrier, and said slide bushing extending into said screw bushing and being axially displaceable relative thereto in releasing said dies from the threading position.

12. A threading die head, as set forth in claim 11, wherein a securing device extending transversely through said die carrier into engagement with said screw bushing for preventing unintentional rotation therebetween.

13. A threading die head, as set forth in claim 1, wherein said sensing bolt extends axially through said slide bushing with its end more remote from said dies extending axially outwardly from said slide bushing, and a securing ring mounted on the end of said sensing bolt which extends outwardly from the end of said slide bushing more remote from said dies.

14. A threading die head, as set forth in claim 1, wherein an annular collar projecting laterally outwardly from said sensing bolt and spaced between the end of said slide bushing within the bore in said carrier and the contact surface on said sensing bolt, said annular collar projecting transversely from said bolt beyond the inner surface of said slide bushing at its end adjacent said annular collar so that the end surface of said slide bushing acts as a stop for limiting the axial displacement of said sensing bolt.

15. A threading die head, as set forth in claim 1, wherein the opposite end of said die carrier from the end adjacent said annular flange having a plurality of angularly spaced radially extending grooves, one of said dies located in each of said grooves, and an annular cover plate removably attached to the end of said die carrier for securing said dies within said grooves.

16. A threading die head, as set forth in claim 1, wherein said means on said holding bolts for securing said bolts to said flange comprises surfaces formed on the ends of said bolts and extending laterally outwardly therefrom, and recesses formed in said flange for receiving the surfaces on said holding bolt for securing said holding bolts to said flange.

Claims

1. A threading die head for insertion into a thread-cutting machine for cutting threads in a workpiece, said die head including an annularly shaped die carrier having a bore extending axially therethrough, a plurality of disengageable threading dies mounted in said die carrier, holding cams arranged to secure said threading dies in the threading position, and means associated with said cams for releasing said dies from the threading position, wherein the improvement comprises that said die carrier is axially elongated, a plurality of axially movable angularly spaced holding rods extending axially through said die carrier, said means for releasing said die comprises an annular flange located on one end of said die carrier spaced axially from said dies and having an opening therethrough, means for resiliently biasing said flange in the axial direction away from said dies, means for securing said holding bolts to said flange, a slide bushing positioned within an extending axially through the opening in said flange and the bore in said die carrier, said slide bushing disposed in detachable engagement with said flange, a sensing bolt arranged coaxially within and extending through said slide bushing, said sensing bolt having a contact surface arranged to engage the workpiece, said sensing bolt having an annular groove formed on its surface located radially inwardly of the inner surface of said slide bushing, said slide bushing having at least one opening extending through its wall from its outer to its inner surface, a ball positioned within the opening in said slide bushing and having a diameter substantially equal to the wall thickness of said slide bushing and the depth of the annular groove in said sensing bolt, said die carrier having an annular groove formed in the surface of its bore and the annular groove in said die carrier has a depth substantially equal to the depth of the annular groove in said sensing bolt so that said ball can be seated within said annular groove in said die carrier and the opening in said slide bushing, each of said holding bolts at the ends opposite the end secured to said flange having one of said holding cams mounted thereon, so that with said ball positioned within the opening in said slide bushing and in the annular groove in said die carrier said slide bushing is held against axial displacement relative to said die carrier with said dies secured in the threading position by said holding cams and with the annular groove in said sensing bolt displaced axially from said opening in said slide bushing, and when said contact surface of said sensing bolt in engagement with the workpiece displaces said sensing bolt axially within said slide bushing until the annular groove therein is registered opposite the opening in said slide bushing and said ball is displaced inwardly into the annular groove in said sensing bolt affording axial displacement of said slide bushing and flange relative to said die carriEr due to said means for resiliently biasing said flange and the axial displacement of said flange effecting the axial withdrawal of said holding cams from said dies for releasing said dies from the threading position.

3. A threading die head, as set forth in claim 1, wherein said means for resiliently biasing said flange comprises a plurality of bores formed in said die carrier with the axis of said bores extending in the axial direction of said die carrier, and a spring positioned within each of said bores and contacting said flange so that said springs bias said flange in the axial direction away from said dies.

5. A threading die head, as set forth in claim 4, wherein said means for securing said flange and said sliding bushing against relative rotation comprises a securing device extending through said flange into engagement with said sliding bushing in the range of the threaded connection therebetween.

6. A threading die head, as set forth in claim 1, wherein a plurality of follower cams mounted on the circumferential periphery of said die carrier and said die cams arranged for engagement within a thread-cutting device in the manner of a bayonet closure for securing said threading die head to the thread-cutting device.

9. A threading die head, as set forth in claim 1, wherein a bore extending into said sensing bolt transversely of the axis thereof and within the range of said sensing bolt positioned within said slide bushing, a ball spring assembly positioned within said bore in said sensing bolt, and the recess formed in the inner surface of said slide bushing opposite the bore in said sensing bolt so that said ball is spring biased into the recess in said slide bushing for preventing accidental axial displacement of said sensing bolt relative to said slide bushing.

10. A threading die head, as set forth in claim 1, wherein said slide bushing having a number of openings therein and one of said balls located within each of said openings for interconnecting said die carrier and said slide bushing.