GB1600264A - Thread chaser carrier for use in a diehead - Google Patents

Description

(54) THREAD CHASER CARRIER FOR USE IN A DIE-HEAD (71) We, ALFRED HERBERT LIMITED, a British Company located at P.O. Box 30, Edgwick Works, Coventry, CV6 5GT, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a thread chaser carrier for mounting a thread chaser element on a die-head adapted for use in a machine tool.

Our British Patent No. 1552433 describes a chaser carrier comprising a body having a longitudinal recess for reception of a thread chaser element, said recess being generally channel shaped in cross-section and being defined by a base and a pair of opposed sides, one of said sides having a surface inclined to the longitudinal axis of said body to align the chaser element therein at the required helix angle when placed in the recess, the body being deformable so that said sides are relatively movable generally parallel to each other in a direction generally transverse to the recess to grip the chaser element within said recess.

An object- of the present invention is to provide an improvement in or modification of the chaser carrier described in our aforesaid Patent whereby a chaser can be inclined at differing helix angles without substitution of the entire carrier and without the necessity to provide a separate gripping chaser holder.

According to the invention, a thread chaser carrier comprises a body adapted to be mounted on a die-head, the body having a recess to receive a thread chaser element, an insert adapted to be position in the recess with a surface thereof against one side of the recess and another surface arranged to be engaged by the chaser element when the latter is placed in the recess such that said another surface locates the chaser in the recess at the desired helix angle, means adapted to co-operate with the insert, when the latter is in the recess, to locate the insert in a fixed longitudinal position, and a clamd operable to apply a retaining force to the chaser in the recess.

Preferably, the clamp is supported on the body by way of a curved surface which permits the clamp a degree of rocking movement relative to the body to enable its clamping position to vary according to the helix angle of the insert.

The invention will now be described, by way of example, with reference to the accompanying drawings in which: Figures 1 and 2 are respective side elevations of a chaser carrier of the invention; Figure 3 is an end elevation of the carrier of Figures 1 and 2; Figure 4 is a side elevation of a component of the carrier of Figures 1 and 3, and Figure 5 is a section along the line X-X of Figure 4.

Referring to Figures 1 to 3 of the drawings, these show a chaser carrier having a body 1 and a shank 2 for rotatably mounting the carrier on a die-head in known manner. The carrier has a recess indicated generally at 3 extending perpendicularly to the rotary axis of the shank 2 to receive a thread chaser element 4 and partially, an insert 5 which is housed within a groove 6 of the body 1 and located in a fixed position longitudinally of the groove by a peg 7 extending from the body to engage in a notch 8 of the insert. The base 9 of the groove 6 lies in a plane perpendicular to the base 10 of the recess 3 and is engaged by one side 11 of the insert 6.The opposite side 12 of the insert is longitudinally inclined with respect to the side 11 and also undercut at 13, so that in co-operation with an opposed undercut side 14 of the thread chaser element 4, there is formed within the recess a female formation of generally dovetailed configuration to receive a complementary portion 15 of the chaser element 4. It will be seen that, with the insert 5 in position within the groove 6, the side 12 of the insert is inclined to the longitudinal axis of the holder, the angle of inclination being chosen so that a chaser element 4 disposed within the recess and engaging the sides 12 will be disposed at the required helix angle, as will be clearly seen from Figure 2.

The chaser element 4 is held in position in the carrier by means of a clamp 16 which engages one side of the element 4 and has a clamping screw 17 engaged in a threaded hole of the body 1 to provide a clamping force on the chaser element. An inclined surface 18 of the clamp engages a correspondingly inclined surface 19 of the body and a further inclined surface 20 engages the correspondingly inclined side of the dovetail portion 15 of the chaser element.

It will be readily appreciated that the helix angle of the chaser element 4 can readily be changed by unclamping the element and simply replacing the insert 5 with another having the required helix angle. In order to accommodate the resuIting slight change in position of the chaser element, the surface 19 of the clamp is curved along a part of its length to permit a small degree of rocking movement of the clamp as it is tightened against the new chaser element. To facilitate such racking, the side 25 of the clamp is arranged to have a clearance from the adjacent side of the body.

When a chaser element 4 is initially inserted into the carrier, it is necessary to adjust its position accurately in relation to the centre of rotation of the die-head with which the carrier is to be used. For this purpose, there is provided an adjusting device which includes a support member in the form of a plug 26, press-fitted into the body I and retained by an axially extending doweI or spring pin 27. An externally threaded adjusting screw 28 is mounted in a threaded bore of the plug 26 and has a nose 29 which engages an adjacent end surface 30 of the element 4 so that, by rotating the screw 28 in one direction, the chaser element can be slidably adjusted downwardly as seen in Figure 2.

The invention will be seen to provide a carrier for a thread chaser element which is simple to use and, because it eanbles a range of helix angles to be accommodated simply by providing different inserts and without duplicating the entire chaser carrier, it is relatively inexpensive to manufacture.

WHAT WE CLAIM IS:- 1. A thread chaser carrier comprising body adapted to be mounted on a die-head, the body having a recess to receive a thread chaser element an insert adapted to be positioned in the recess with a surface thereof against one side of the recess and another another surface arranged to be engaged by the chaser element when the latter is placed in the recess such that said another surface locates the chaser in the recess at the desired helix angle, means adapted to co-operate with the insert, when the latter is in the recess, to locate the insert in a fixed longitudinal position, and a clamp operable to apply a retaining force to the chaser in the recess.

2. A thread chaser carrier according to Claim 1 wherein the clamp is supported on the body by way of a curved surface which permits the clamp a degree of rocking movement relative to the body to enable its clamping position to vary according to the helix angle of the insert.

3. A thread chaser carrier according to Claim 1 or Claim 2 wherein means are provided for adjusting the position of the chaser along the recess.

4. A thread chaser carrier according to Claim 3 wherein the adjusting means is a screw-threaded element engaged in a normally relatively stationary part of the carrier and engaging a chaser element when disposed therein.

5. A thread chaser carrier according to Claim 4 wherein the element is threadedly engaged with a plug fixedly mounted in the body.

6. A thread chaser carrier according to any one of the preceding claims wherein said one side of the recess is within and forms the base of a groove formed in a side wall of the recess, the insert being disposed within the groove against said base.

7. A thread chaser carrier according to Claim 6 wherein the insert is located longitudinally of the groove by a projection extending from the body to engage in a notch in the insert.

8. A thread chaser carrier according to Claim 6 or Claim 7 wherein the base of the groove lies in a plane perpendicular to a base of the recess against which the chaser element is clamped.

9. A thread chaser carrier according to any one of the preceding claims wherein that side of the insert to be engaged by the chaser element is arranged to form, with the opposed side of the recess, a female formation of generally dovetailed configuration to receive a complementary portion of the element.

10. A thread chaser carrier according to Claim 9 wherein an inclined surface of the clamp engages a correspondingly inclined surface of the body and a further inclined surface of the clamp engages a correspond

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. disposed at the required helix angle, as will be clearly seen from Figure 2. The chaser element 4 is held in position in the carrier by means of a clamp 16 which engages one side of the element 4 and has a clamping screw 17 engaged in a threaded hole of the body 1 to provide a clamping force on the chaser element. An inclined surface 18 of the clamp engages a correspondingly inclined surface 19 of the body and a further inclined surface 20 engages the correspondingly inclined side of the dovetail portion 15 of the chaser element. It will be readily appreciated that the helix angle of the chaser element 4 can readily be changed by unclamping the element and simply replacing the insert 5 with another having the required helix angle. In order to accommodate the resuIting slight change in position of the chaser element, the surface 19 of the clamp is curved along a part of its length to permit a small degree of rocking movement of the clamp as it is tightened against the new chaser element. To facilitate such racking, the side 25 of the clamp is arranged to have a clearance from the adjacent side of the body. When a chaser element 4 is initially inserted into the carrier, it is necessary to adjust its position accurately in relation to the centre of rotation of the die-head with which the carrier is to be used. For this purpose, there is provided an adjusting device which includes a support member in the form of a plug 26, press-fitted into the body I and retained by an axially extending doweI or spring pin 27. An externally threaded adjusting screw 28 is mounted in a threaded bore of the plug 26 and has a nose 29 which engages an adjacent end surface 30 of the element 4 so that, by rotating the screw 28 in one direction, the chaser element can be slidably adjusted downwardly as seen in Figure 2. The invention will be seen to provide a carrier for a thread chaser element which is simple to use and, because it eanbles a range of helix angles to be accommodated simply by providing different inserts and without duplicating the entire chaser carrier, it is relatively inexpensive to manufacture. WHAT WE CLAIM IS:-

1. A thread chaser carrier comprising body adapted to be mounted on a die-head, the body having a recess to receive a thread chaser element an insert adapted to be positioned in the recess with a surface thereof against one side of the recess and another another surface arranged to be engaged by the chaser element when the latter is placed in the recess such that said another surface locates the chaser in the recess at the desired helix angle, means adapted to co-operate with the insert, when the latter is in the recess, to locate the insert in a fixed longitudinal position, and a clamp operable to apply a retaining force to the chaser in the recess.

2. A thread chaser carrier according to Claim 1 wherein the clamp is supported on the body by way of a curved surface which permits the clamp a degree of rocking movement relative to the body to enable its clamping position to vary according to the helix angle of the insert.

3. A thread chaser carrier according to Claim 1 or Claim 2 wherein means are provided for adjusting the position of the chaser along the recess.

4. A thread chaser carrier according to Claim 3 wherein the adjusting means is a screw-threaded element engaged in a normally relatively stationary part of the carrier and engaging a chaser element when disposed therein.

5. A thread chaser carrier according to Claim 4 wherein the element is threadedly engaged with a plug fixedly mounted in the body.

6. A thread chaser carrier according to any one of the preceding claims wherein said one side of the recess is within and forms the base of a groove formed in a side wall of the recess, the insert being disposed within the groove against said base.

7. A thread chaser carrier according to Claim 6 wherein the insert is located longitudinally of the groove by a projection extending from the body to engage in a notch in the insert.

8. A thread chaser carrier according to Claim 6 or Claim 7 wherein the base of the groove lies in a plane perpendicular to a base of the recess against which the chaser element is clamped.

9. A thread chaser carrier according to any one of the preceding claims wherein that side of the insert to be engaged by the chaser element is arranged to form, with the opposed side of the recess, a female formation of generally dovetailed configuration to receive a complementary portion of the element.

10. A thread chaser carrier according to Claim 9 wherein an inclined surface of the clamp engages a correspondingly inclined surface of the body and a further inclined surface of the clamp engages a correspond

ingly inclined side of said complementary portion of the chaser element.

11. A thread chaser carrier substantially as hereinbefore described with reference to the accompanying drawings.