NZ212809A

NZ212809A - Self centering tool holder for lathe

Info

Publication number: NZ212809A
Application number: NZ21280985A
Authority: NZ
Inventors: Bernard Sydney Philpott
Original assignee: Bernard Sydney Philpott
Priority date: 1985-07-19
Filing date: 1985-07-19
Publication date: 1987-07-31
Also published as: AU6026386A; AU583138B2

Description

212809 M.2. PATENT Oi ;- !C£ " A AuAasnqgw 22 Ju. 1935 rtscsr^p PATENTS FORM NO: 5 PATENTS ACT 1953 No: 212809 Date: 19th Julyl985 COMPLETE SPECIFICATION "CENTERING TOOL HOLDER" I, BERNARD SYDNEY PHILPOTT a New Zealand citizen of 38 Massey Crescent, Christchurch, New Zealand, hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- 212309 The present: invention relates to a tool holder for holding tools on a lathe or similar machine tool.

At present, a lathe tool normally is mounted on the toolpost of the lathe, and whenever a new tool is fitted to the lathe it must be adjusted in the toolpost (by shims) until the cutting edge of the tool coincides with the centre line of the lathe. This adjustment can take some time, and can be a serious inconvenience if a piece of machinery requires the use of several different tools. One way to overcome this difficulty is to use a 'quick-change' toolholder which comprises a number of tool-holder units, each of which holds one tool, and is pre-set to hold that tool at the correct height when fitted to the toolholder body. Thus, if a large number of different tools are required for a particular machining job, each tool is fitted to a different toolholder unit which is adjusted to the correct height before the job is started. Then as the job progresses, each toolholder unit with its tool is mounted on the toolholder body in turn, and the tools do not require further adjustment. However, a quick-change toolholder of this type is expensive, because to be of practical value it must provide enough toolholder units for each tool to be used.

An object of the present invention is the provision of a tool holder which overcomes the above-described drawbacks and provides the advantages of a quick-change toolholder at a much lower cost.

The present invention provides a toolholder comprising: a stem connected to two support members which extend outwards therefrom to form a V-cross section support, and securing 212309 means for securing a tool with the longitudinal shank of the tool making equal contact with each of the facing surfaces of the support members; said stem being dimensioned and arranged to be securable in a toolholder of a lathe or similar machine.

The included angle between said facing surfaces preferably is 90°.

Preferably, said securing means comprises: a brace of generally U-shaped cross-section, one side of said brace being securable to the outer edge of one support member and the other side of said brace being securable to the outer edge of the other support member, such that said brace forms a bridge above said facing surfaces; and a securing member engagable with said brace and arranged to be movable in either direction along a line which bisects the included angle between said facing surfaces.

The securing means may comprise one or more braces, which may be rigidly or slidably engaged with the securing members. By way of example only, a preferred embodiment of the present invention is described in detail with reference to the accompanying drawings, in which:- Fig. 1 is a side view of a toolholder in accordance with the present invention; Fig. 2 is a front view taken in the direction of arrow 2 of Fig 1; and Fig. 3 is a rear view taken in the direction of arrow 3" ' of Fig. 1.

In all views, the centre line of the lathe is designated Referring to the drawings, a toolholder 1 comprises a stem 212309 3 of rectangular cross-section, formed integrally with two support members 4 which extend outwards from the stem 3. The facing surfaces 5 of the support members 4 are smooth and flat and the included angle X between said inner surfaces is 90°.

The outer edge of each support member 4 is enlarged in width and is angled to provide a projection 6 the outer face 7 of which lies in a plane parallel to the planes of the side faces of the stem 3.

A pair of spaced, U-cross-section braces 8 is arranged to link the support members 4 adjacent each end of the toolholder. Each brace 8 comprises an arched portion formed with a channel 9 on its inner surface, adjacent each free end of the brace. Each channel 9 is dimensioned to be an easy sliding fit over the corresponding projection 6, so that each brace 8 can be slidably engaged with each of the projections 6, retaining the brace 8 on the support members 4.

Each brace 8 is formed with a screw threaded hole in the centre of the arched portion, and a screw 10 is engaged in said hole. The longitudinal axis of each screw 10 bisects the angle X between the inner surfaces 5 of the support members 4. Two braces 8 are shown in the drawings, one at each end of the support members, but the braces can be positioned at any spaced positions along the length of the support members, and any number of braces can be used. Alternatively, a single solid brace extending all or most • of the distance between the ends of the support members can' be used.

The braces 8 are shown as slidably mounted on the support 212309 members 4 but they can be rigidly secured to the projections 6 of said members.

The above-described toolholder is used as follows:- the toolholder is mounted on the lathe toolpost, and a test bar is passed through the toolholder, between the support members 4, and is supported between the tailstock and headstock centres of the lathe. The toolholder is then adjusted in height as necessary, by means of shims 11, until the test bar contacts each of the inner surfaces 5 of the support members A' equally i.e. the centre line of the lathe bisects the angle X of the toolholder. Once this is achieved, the shims are permanently or semi-permanently secured to the stem of the toolholder, so that the toolholder can be removed from the lathe, and replaced as required, without needing further adjustment.

The toolholder can now be used to hold any tool which has a shank of circular cross-section or a shank which is of regular cross-section and has a cross-sectional shape which provides two mutually perpendicular faces (not necessarily adjacent).

The tool is held in the toolholder by placing the tool shank between the facing surfaces 5 of the support members 4, with the longitudinal axis of the shank parallel to the line 12 at the junction of the facing surfaces 5. The screws 10 are then adjusted until the inner ends of said screws press the shank of the tool firmly into equal contact with the facing surfaces 5, holding the tool securely in the tool-holder. Since the angle X between said inner surfaces is bisected by the screws 10, the tool is automatically centred 212309 in the toolholder, and when the toolholder is secured to the toolpost, the tool is also centred relative to the centre-line of the lathe, because the toolholder has been pre-centred as described above. Different' tools can be quickly and easily fitted to the toolholder simply by releasing and re-tightening the screws 10, without any further centering being needed.

It will be appreciated that the angle X between the surfaces 5 need not be 90° but can be any other angle, providing always that the longitudinal axes of the screws 10 bisect this angle. However, if the angle X is not 90°, the tools secured in the toolholder must have a shank which is either circular in cross-section or has a cross-sectional shape compatible with said angle X in that the angles between faces of the shank in cross-section are equal to, or multiples or sub-multiples of, said angle X.

Claims

I' •% _ 7 _ $\2<609 WHAT I CLAIM IS:-

1. A toolholder for a lathe or similar machine, said toolholder comprising: a stem connected to two support members which extend outwards therefrom to form a V-cross-section support, and securing means for securing a tool with the longitudinal shank of the tool making equal contact with each of the facing surfaces of the support members; said stem being dimensioned and configured so as to be securable in a toolholder of a lathe or similar machine. I i! P. L. B. & A per-2^jL~. /A / S If J

2. The toolholder as claimed in Claim 1 wherein said securing means comprises: a brace of generally U-shaped cross section; one side of said brace being securable to the outer edge of one support member and the other side of said brace being securable to the outer edge of the other ocr«u support member, such that said brace forms a bridge above said facing surfaces; and a securing member engagable with said brace and arranged to be movable in either direction along a line which bisects the included angle between said facing surfaces.

3. The toolholder as claimed in claim 2 wherein said securing means comprises a single brace.

4. The toolholder as claimed in claim 2 wherein said securing means comprises two or more spaced braces.

5. The toolholder as claimed in any one of claims 2-4 : .7 Z2ALA?<0 18 MAY 1987 w lerein the or each said brace is rigidly secured to said PATENT OFRC ■ ' /' V."" ■... 1 . ■ ' -- 4k) ' " 8 " support members.

6. The toolholder as claimed in any one of claims 2-4 wherein the or each said brace is slidably secured to said support members.

7. The toolholder as claimed in claim 6 wherein the or .-\L. L". :aA. each said brace is formed with a channel on the internal jU/ ■ surface adjacent each end thereof, and the edge of edge 3.^ iA support member is formed with a projection dimensioned to be a sliding fit with the corresponding channel. \

8. The toolholder as claimed in any preceding claim wherein the included angle between said facing surfaces is 90°.

9. A toolholder for a lathe or similar machine and substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

10. The combination of a toolholder as claimed in claim 2 and a tool having a shank of circular cross-section, wherein the included angle between said facing surfaces is £ I 90°.

11. The combination of a toolholder as claimed in claim 2 and a tool having a shank of circular cross-section, wherein the included angle between said facing surfaces is than 90 °. N.Z. PATENT Of-'FiCc 1 MAY 1987 RECEIVED - 9 - 212809

12. The combination of a toolholder as claimed in claim 2 and a tool having a shank of non-circular cross-section, wherein the angles between adjacent faces of the shank in cross-section are equal to, or multiples or sub-multiples of, the included angle between said facing surfaces.

13. The combination of a toolholder and a tool, substantially as hereinbefore described with reference to and as shown in the accompanying drawings. Bernard Sydney Philpott, by his authorised Agents, P.L. BERRY & ASSOCIATES.