IE904017A1

IE904017A1 - A work piece stabilising device

Info

Publication number: IE904017A1
Application number: IE401790A
Authority: IE
Inventors: James Patrick Hayes; Michael Joseph Hayes; John Joseph Byrne
Original assignee: Buchlane Invest Ltd
Priority date: 1990-11-08
Filing date: 1990-11-08
Publication date: 1992-05-20
Also published as: GB2249514B; ZA909181B; GB9122579D0; IE65042B1; GB2249514A

Abstract

The device (1) for stabilising a long work piece (2) in a lathe is mounted on a carriage (15) of the lathe (3). The stabilising device (1) comprises a framework (12) and a support member (20) slidable in the framework (12) and secured in position by a grub screw. A work piece receiving bore (26) defining the cross sectional area of the work piece (2) rotatably and slidably engages the work piece (2) for stabilising the work piece (2) adjacent a cutting tool (7). A strut (29) engages the support member (20) to resist upward pressure of the cutting tool (7) on the work piece (2).

Description

The present invention relates to a work piece stabilising device for use in a lathe, and the invention also relates to a method for turning a work piece in the lathe to form a component using the work piece stabilising device. Further, the invention relates to a component turned from a work piece using the method and work piece stabilising device.

Where it is desired to form a component by turning in a lathe from a relatively long work piece, as well as mounting the work piece in the chuck of the lathe, it is normally necessary to support the work piece at another position spaced apart from the chuck. The work piece may be supported by a centre support device which engages a bore drilled into the end of the work piece remote from the chuck. Alternatively, a work piece stabilising device may be used. Such work piece stabilising devices generally comprise a framework which is mounted on the runners in the bed of the lathe. Two elongated engagement members are mounted in the framework and are movable along axes disposed at an angle to each other and extending transversely of the rotational axis of the work piece. The engagement members are moved relative to the framework so that their free ends engage the surface of the work piece as the work piece rotates. The engagement members in general terminate in bearing surfaces.

However, while such devices are reasonably adequate for supporting work pieces of relatively large diameter, they are, in general, unsuitable for supporting work pieces of relatively small diameter, typically work pieces of up to 25 mm diameter. Even in large diameter components, such work piece stabilising devices are not always suitable, since only two point support is provided by the engagement members and these two points are usually at right angles to each other. One engagement member normally engages the top of the work piece while the other engagement member engages the side of the work piece opposite the side engaged by the cutting tool. In other words, the two engagement members extend respectively horizontally and vertically from the framework to engage the work piece.

A further disadvantage of such known work piece stabilising devices is that it is frequently difficult to align the engagement members with the work piece so that the horizontal and vertical axes of the engagement members intersect at a point coincident with the rotational axis of the work piece. Needless to say, in the event of the point of intersection of the vertical and horizontal axes not coinciding with the rotational axis of the work piece the work piece will be eccentrically turned.

There is therefore a need for a work piece stabilising device which overcomes the problems of prior art devices.

There is also a need for a method for turning a component from a work piece using the stabilising device. Further, there is a need for a component produced from the method and device.

The present invention is directed towards providing such a stabilising device, a method and a component produced from the method and device.

According to the invention, there is provided a work piece stabilising device for stabilising an elongated work piece in a lathe, the stabilising device comprising a framework, a work piece supporting means for rotatably and slidably supporting the elongated work piece, the work piece supporting means being mounted on the framework and defining a central support axis about which the work piece is rotatable and longitudinally slidable, the central support axis being co-axial with the rotational axis of the lathe chuck, and mounting means for mounting the framework for travelling along the bed of the lathe with the central support axis co-axial with the rotational axis of the chuck, wherein the work piece supporting means comprises a support member having a work piece receiving bore extending therethrough for rotatably and slidably receiving the work piece, the bore defining the central support axis.

In one embodiment of the invention, the work piece supporting means comprises an elongated support member slidable in the framework transversely of the central support axis, and securing means for selectively securing the support member relative to the framework.

Preferably, the support member is slidable in a bore extending through portion of the framework. Advantageously, the securing means is provided by a grub screw in the framework engagable with the support member.

In one embodiment of the invention, the cross section of the work piece receiving bore substantially defines the outer cross section of the work piece.

Preferably, a strut extends from the framework, the strut being engagable with the work piece supporting means for preventing upward movement of the work piece supporting means. Advantageously, the strut is releasably engagable with the work piece supporting means.

In one embodiment of the invention, the strut is provided by an elongated strut slidably mounted in the framework.

Preferably, the strut is vertically slidable in the framework.

Additionally, the invention provides a method for stabilising an elongated work piece being turned in a lathe to form a component, the method comprising the step of clamping the work piece in a chuck of the lathe to be rotated about the rotational axis of the chuck, supporting the work piece in the work piece receiving bore of a work piece stabilising device according to the invention, rotating the work piece, bringing a cutting tool mounting on a saddle of the lathe into engagement with the work piece.

In one embodiment of the invention, the work piece stabilising device is mounted on a carriage of the lathe intermediate the chuck and the cutting tool mounted on the saddle.

In another embodiment of the invention, the method further includes the step of boring the work piece receiving bore in the work piece supporting means prior to supporting the work piece in the work piece stabilising device, the work piece receiving bore being bored in the work piece supporting means by a boring tool mounted in the chuck, and the stabilising device being moved longitudinally towards the chuck for boring the hole. Advantageously, the work piece receiving bore is reamed prior to supporting the work piece in the work Ί piece support means .

Further, the invention provides a component turned from a work piece using the method of the invention.

Additionally, the invention provides a component turned 5 from a work piece using the work piece stabilising device according to the invention.

Additionally, the invention provides a component turned from a work piece using the work piece stabilising device according to the invention and the method according to the invention.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a work piece stabilising device according to the invention, Fig. 2 is a side elevational view of the work piece stabilising device of Fig. 1, Fig. 3 is a partly schematic perspective view of a lathe illustrating the work piece stabilising device of Fig. 1 in use, Fig. 4 is a front elevational view of the lathe of Fig. 3 also illustrating the work piece stabilising device of Fig. 1 in use, and Fig. 5 is a perspective view of a component turned using the lathe and the work piece stabilising device of Fig. 1.

Referring to the drawings, there is illustrated a work piece stabilising device according to the invention indicated generally by the reference numeral 1 for supporting an elongated work piece 2 in a lathe 3 while the work piece 2 is being turned to produce a plurality of components, in this case circular section plugs 40, each with a flange 41. One of the components 40 is illustrated in Fig. 5. Before describing the work piece stabilising device, the lathe 3 which is illustrated schematically in Figs. 3 and 4 will first be described. Such lathes will be well known to those skilled in the art, and only those parts of the lathe 3 which are required to understand the invention will be described.

The lathe 3 comprises a bed 4. A chuck 5 rotatable in the bed 4 about a rotational axis receives and rotates the work piece 2. A saddle 6 carries a cutting tool 7 for engagement with the work piece 2 for turning thereof. The saddle 6 is mounted on a carriage 13 and is slidable transversely relative to the rotational axis of the chuck 5. The carriage 13 is slidably carried on a pair of runners 8 in the bed of the lathe 4. A lead screw 9 is provided for driving the carriage 13 longitudinally along the runners 8 towards and away from the chuck 5. A centring member 10 is slidably mounted in a support housing 11 for engaging a bore (not shown) in the free end of the work piece 2 for centring the free end. The support housing 11 is slidable on the runners 8. In normal use of the lathe, the work piece 2 is clamped in the chuck 5 and is rotated. The centring member 10 may or may not be used. The carriage 13 is moved longitudinally along the runners 8 so that the cutting tool 7 is brought into a position radially spaced from but co-inciding with the work piece 2. The saddle 6 is then transversely moved relative to the rotational axis of the chuck 5 to bring the cutting tool 7 into engagement with the work piece 2.

Returning now to the work piece stabilising device 1, the work piece stabilising device 1 comprises a framework 12 having a base member 14, an upstanding member 17 and a transversely extending top member 18 all formed integrally of cast iron. Mounting means in this embodiment of the invention for mounting the device 1 to the carriage 13 intermediate the chuck 5 and the cutting tool 7 comprises a pair of spaced apart holes 16 extending through the base 14 for engaging screws 15 for securing the base 14 to the carriage 13.

A work piece supporting means in this case provided by an elongated support member 20 of bronze of circular cross section is slidable horizontally in a bore 22 in the upstanding member 17. Securing means comprising a grub screw 23 through a threaded hole 24 in the upstanding member 17 engages the support member 20 for securing the support member 20 in any desired position relative to the framework 12. The bore 22 extends horizontally through the upstanding member 17 and transversely of the rotational axis of the chuck 5 and in turn the work piece 2. The bore 22 is provided at a height on the upstanding member 17 relative to the holes 16 so that the central axis of the support member 20 substantially intersects the rotational axis of the chuck.

A work piece receiving bore 26 of circular cross section and of diameter substantially similar to the diameter of the work piece 2 is formed in the support member 20 for rotatably and slidably supporting the work piece 2. The bore 26 defines a central support axis which is co-axial with the rotational axis of the chuck 5 and work piece 2. The diameter of the work piece receiving bore 26 substantially defines the outer cross section of the work piece and is of size sufficient to permit rotation of the work piece 2 within the support member 20 and also to permit longitudinal sliding of the work piece 2 in the bore 26. Further, the bore 26 should be of sufficient size to adequately support the work piece 2 in the support member 20. In practice, it has been found that a bore 26 with a diametrical clearance of approximately + or - 0.01 mm of the diameter of the work piece 2 provides adequate rotational and slidable engagement while at the same time adequate support for the work piece 2.

A strut 29 slidable vertically in a bore 30 in the top member 18 releasably engages the support member 20 for steadying the support member 20 by counter-acting the upwardly directed cutting forces of the cutting tool 7 on the work piece 2. A threaded flange 32 on the top member 18 engages a correspondingly threaded portion 33 of the strut 29 for raising and lowering the strut 29. A grub screw 35 through a threaded hole 36 in the top member 18 engages the strut 29 for securing the strut 29 in the desired position in the bore 30.

In use, the work piece stabilising device 1 may be provided with the support member 20 with the work piece receiving bore 26 of the desired diameter predrilled and reamed. In such cases, when the stabilising device 1 is mounted on the carriage 13, the support member 20 is adjusted horizontally through the bore 22 until the central support axis 25 of the work piece receiving bore 26 is co-axial with the rotational axis of the chuck 5.

When the central support axis 25 and the rotational axis of the chuck 5 co-incide, the support member 20 is secured in position by tightening the grub screw 23. The work piece 2 is then entered through the chuck 5, and is passed through the work piece receiving bore 26. In general, the centring member 10 is engaged in a centring bore (not shown) in the free end of the work piece 2 to support the free end of the work piece 2. The strut 29 is then adjusted downwardly to engage the support member 20 for steadying the support member 20. When the strut 29 engages the support member 20, the grub screw 35 is tightened, thus securing the strut 29 in the desired position. The chuck 5 is then rotated and the carriage 13 and saddle 6 are moved to bring the cutting tool 7 into engagement with the work piece to turn the first component 40. When the first component 40 has been turned, it is parted off by a parting off tool, and by operating the carriage and saddle appropriately, the cutting tool 7 is brought into engagement with the work piece again to turn the next component.

However, it has been found preferable to bore out the work piece receiving bore 26 in the support member 20 using a boring tool mounted in the chuck 5 after the support member 20 has been secured by the grub screw 23 in the upstanding member 17. In this way, the central support axis 25 of the work piece receiving bore 26 is automatically co-axial with the rotational axis of the chuck 5. To bore the work piece receiving bore 26 in the support member 20 the following method is used. With the stabilising device secured to the carriage 13, the support member 20 is secured in the upstanding member 17 by tightening the grub screw 23. A boring tool of the appropriate size is mounted in the lathe chuck 5. The carriage 13 is moved longitudinally along the runners 8 to bring the support member 20 into engagement with the boring tool. The carriage is then moved slowly towards the chuck 5, thus causing the boring tool to bore the work piece receiving bore 26. The work piece receiving bore 26 is then reamed by mounting a reaming tool of the appropriate diameter in the chuck. The work piece stabilising device is then ready for use, and the work piece 2 is passed through the chuck 5 and the work piece receiving bore 26 in the stabilising device 1. The centring member 10, if desired, may be engaged in a centring bore (not shown) in the work piece 2 and the strut 29 is then secured in engagement with the support member 20 as already described. Thereafter, operation of the lathe to form the components using the stabilising device 1 to stabilise the work piece is similar to the method of operation of the lathe just described.

During turning of the work piece should the work piece receiving bore 26 increase in diameter as a result of wear, a fresh work piece receiving bore 26 may be bored and reamed in the support member 20. This merely requires releasing the grub screw 23 and sliding the support member 20 in the direction of the arrow A, see Fig. 2, to permit a fresh work piece receiving bore 26 to be bored through the support member 20.

The advantages of the invention are many. Firstly, by virtue of the fact that the work piece is rotatably supported in the work piece receiving bore 26 in the support member, the work piece stabilising device positively locates and stabilises the work piece. Irrespective of the work piece diameter, the work piece stabilising device achieves results which are substantially better than any known work piece stabilising device, and indeed, the results which have been achieved are quite surprising. In particular, the work piece stabilising device is suitable for supporting work pieces down to the very smallest of diameters, and it has been found that it is particularly suitable for supporting work pieces of relatively small diameter, typically work pieces of diameter less than 25 mm.

Known work piece stabilising devices do not adequately support work pieces of such relatively small diameter.

Furthermore, by virtue of the fact that the strut bears on the upper surface of the support member, the support member is also stabilised in a vertically upwardly direction. This is the direction in which the cutting action of the cutting tool acts to cause upward pressure on the work piece. In general, this upward pressure tends to cause the work piece to run eccentrically, thereby providing an eccentrically turned component. The strut avoids this problem.

While the work piece stabilising device has been described as comprising a framework of particular shape and construction, frameworks of other shape and construction could be used without departing from the scope of the invention. Indeed, it is envisaged in certain cases that the work piece stabilising device need not be formed by a framework. Further, while the support member 20 has been described as being of bronze material, it may be of any other suitable material, and indeed may be of other non-bearing type metal materials, and in such a case, it is envisaged, though not necessarily that inserts of a bearing material may be provided in the support member. Needless to say, where the work piece stabilising device is for use with relatively large diameter work pieces, the portion of the support member in which the work piece receiving bore 26 is to be formed may be of cross section considerably greater than the cross section of the support member engaging the bore 22. In fact, in certain cases, it is envisaged that the work piece support member may be secured to the upstanding member by any means other than engaging a bore, and in certain cases, it is envisaged that the support member need not slidably engage the upstanding member.

While the work piece stabilising device has been described as comprising a strut for stabilising the support member 20 in a vertically upward direction, in certain cases it is envisaged that the strut may be dispensed with altogether. Indeed, where a strut is provided, it is not essential that it should be slidable or movable in the framework, and where it is slidable and/or movable, it need not necessarily be movable along a vertical axis. In certain other cases, it is envisaged that the strut may be mounted in the upstanding member of the framework, or indeed in the base of the framework.

While the stabilising device has been described as being mounted on the carriage of the lathe, it will be appreciated that the stabilising device may be mounted in any other suitable location on the lathe. Indeed, in certain cases, it is envisaged that the stabilising device may be slidably engagable with the runners in the bed of the lathe.

Further, while the work piece stabilising device has been described as being mounted between the chuck and the cutting tool 7, in certain cases, it is envisaged that the work piece stabilising device may be mounted on the side of the cutting tool remote from the chuck.

Claims

1. A work piece stabilising device for stabilising an elongated work piece in a lathe, the stabilising device comprising a framework, a work piece supporting means for rotatably and slidably supporting the elongated work piece, the work piece supporting means being mounted on the framework and defining a central support axis about which the work piece is rotatable and longitudinally slidable, the central support axis being co-axial with the rotational axis of the lathe chuck, and mounting means for mounting the framework for travelling along the bed of the lathe with the central support axis co-axial with the rotational axis of the chuck, wherein the work piece supporting means comprises a support member having a work piece receiving bore extending therethrough for rotatably and slidably receiving the work piece, the bore defining the central support axis.

2. A work piece stabilising device as claimed in Claim 1 in which the work piece supporting means comprises an elongated support member slidable in the framework transversely of the central support axis, and securing means for selectively securing the support member relative to the framework.

3. A work piece stabilising device as claimed in Claim 2 in which the support member is slidable in a bore extending through portion of the framework.

4. A work piece stabilising device as claimed in Claim 2 or 3 in which the securing means is provided by a grub screw in the framework engagable with the support member.

5. 5. A work piece stabilising device as claimed in any of Claims 2 to 4 in which the support member is slidable horizontally.

6. A work piece stabilising device as claimed in any preceding claim in which the cross section of the work 10 piece receiving bore substantially defines the outer cross section of the work piece.

7. A work piece stabilising device as claimed in any preceding claim in which a strut extends from the framework, the strut being engagable with the work piece 15 supporting means for preventing upward movement of the work piece supporting means.

8. A work piece stabilising device as claimed in Claim 7 in which the strut is releasably engagable with the work piece supporting means . 20 9. A work piece stabilising device as claimed in Claim 7 or 8 in which the strut is provided by an elongated strut slidably mounted in the framework. 10. A work piece stabilising device as claimed in Claim

9. In which the strut is vertically slidable in the framework. 5 11. A work piece stabilising device as claimed in any preceding claim in which the framework comprises a base, and an upstanding member extending upwardly from the base, the mounting means being provided on the base for mounting the stabilising device on a carriage of the

10. Lathe.

11. 12. A work piece stabilising device as claimed in Claim 11 in which the mounting means comprises a pair of spaced apart holes for receiving screws for securing the stabilising device to the carriage intermediate the lathe 15 chuck and a cutting tool on a saddle of the lathe.

12. 13. A work piece stabilising device as claimed in Claim 11 or 12 when dependent on Claim 7 in which the framework comprises a transverse cross member spaced apart from the base extending transversely from the upstanding member 20 for slidably supporting the strut.

13. 14. A work piece stabilising device as claimed in Claim 13 in which the strut extends downwardly from the transverse cross member of the framework.

14. 15. A work piece stabilising device substantially as described herein with reference to and as illustrated in the accompanying drawings . 5

15. 16. A method for stabilising an elongated work piece being turned in a lathe to form a component, the method comprising the step of clamping the work piece in a chuck of the lathe to be rotated about the rotational axis of the chuck, supporting the work piece in the work piece 10 receiving bore of a work piece stabilising device according to any of Claims 1 to 15, rotating the work piece, bringing a cutting tool mounting on a saddle of the lathe into engagement with the work piece.

16. 17. A method as claimed in Claim 16 in which the work 15 piece stabilising device is mounted on a carriage of the lathe intermediate the chuck and the cutting tool mounted on the saddle.

17. 18. A method as claimed in Claim 16 or 17 in which the method further includes the step of boring the work piece 20 receiving bore in the work piece supporting means prior to supporting the work piece in the work piece stabilising device, the work piece receiving bore being bored in the work piece supporting means by a boring tool mounted in the chuck, and the stabilising device being moved longitudinally towards the chuck for boring the hole.

18. 19. A method as claimed in Claim 17 in which the work 5 piece receiving bore is reamed prior to supporting the work piece in the work piece support means.

19. 20. A method as claimed in Claim 18 in which a reaming tool is mounted in the chuck, and the work piece supporting means is moved towards the chuck for 10 engagement with the reamer by moving the stabilising device longitudinally towards the chuck.

20. 21. A method as claimed in any of Claims 16 to 20 in which the component is parted off from the work piece.

21. 22. A method for turning a work piece to form a 15 component substantially as described herein with reference to and as illustrated in the accompanying drawings .

22. 23. A component turned from a work piece using the method of any of Claims 16 to 22. 20

23. 24. A component turned from a work piece using the work piece stabilising device of any of Claims 1 to 15.

24.

25. A component turned from a work piece using the work piece stabilising device of any of Claims 1 to 15 and the method of any of Claims 16 to 22.