GB2084064A

GB2084064A - Turning spheres

Info

Publication number: GB2084064A
Application number: GB8030570A
Authority: GB
Original assignee: Firth Brown Castings Ltd
Current assignee: Bradken UK Ltd
Priority date: 1980-09-22
Filing date: 1980-09-22
Publication date: 1982-04-07
Also published as: GB2084064B

Abstract

A lathe for producing curved articles e.g. spheres has a saddle 3 carrying a base plate 2 having a curved track 1. A tool carrier 5 is driven along the track by an electric motor 6 working through a pinion engaging a rack 4 of the track to move a tool in a smooth curved path. <IMAGE>

Description

SPECIFICATION Shaping machine The invention relates to shaping machines such as lathes and to fittings or attachments for such machines.

The normal method used for machining a curved object e.g. a sphere is by a highly skilled operator "stepping-out" the curvature of the surface and then finishing with a series of fine cuts working to the fit of a gauge or template, or by use of a normal lathe but with a template and copying attachment fitted.

This is a refinement of the first method which removes some of the dependence on the operator's skill but because of the characteristics of the machine is still a stepping-out operation.

A third method is by use of a numerical control or computer control machine. The principle is still the same as in the first two methods but the steps are infinitely small.

The present invention provides a shaping machine, e.g. a lathe, comprising means for rotating a workpiece, a tool carrier, for carrying a tool to shape the workpiece, a curved track along which the tool carrier is moveable and means for moving the tool carrier along the track.

The invention includes a shaping machine as claimed in claim 1 wherein the track is part-circular.

The track may be part circular, e.g. semi-circular, or may be a non-circular curve, e.g. semi-elliptical.

The use of a semi-circular track enables the machin ing of a spherical shape.

Preferably, the track comprises a track and the tool carrier comprises a pinion, engaging the rack so that rotation of the pinion drives the carrier along the track.

Preferably, a reversible electric motor is provided connected to rotate the pinion.

Such an electric motor may be controlled to run at infinitely variable speeds by a control unit.

The invention is applicable generally to machines in which a workpiece is rotated for the removal of material by a tool. Machines of this type include lathes and also vertical turning and boring machines.

The invention will be illustrated by the following description of a preferred embodiment with refer ence to and as illustrated in the accompanying drawing, which is a perspective view from the side of a lathe according to the invention.

The lathe shown is a metal-working lathe adapted for machining spheres by the mounting of an attachment in the normal lathe bed on the lathe saddle.

The attachment consists of a guide track attached ;to a base plate 2 which is itself attached to the saddle 3 of the lathe. An accurately machined rack 4 is contained on the outer circumference of the track.

Mounted on the track is a tool carrier 5, integral with which is an electric motor 6 which drives, through a gear box 7, a pinion (not shown) which engages with the rack 4 on the outer circumference of the track.

The motor is governed by a specialised control unit 8 which gives an infinitely variable speed control and therefore drives and controls the movement of the tool carrier around the track at a speed which can be varied to suit the changing diameter and surface speed of the sphere. Metal cutting tools (not shown) are fastened in the tool posts 9 on the tool carrier and by varying the length of tool shank a range of diameters can be cut with any one guide track. A series of tracks can cover a wide range of sizes.

In normal cutting procedure on a standard lathe the contour is produced by a combination of the longitudinal movement of the machine saddle through rotation of a longitudinal lead screw and the transverse movement of the tool post and cutting tool through rotation of another lead screw at the top of the saddle. With the attachment which is the subject of this invention shown in the drawing neither of these are used. Once the attachment is fixed in a correct setting on the saddle, the workpiece is rotated through the headstock in the normal way but all cutting tool movement is controlled by the attachment and this movement is in a truly circlar path thus producing a smooth and true sphere.

The invention includes an attachment for a shaping machine in which a workpiece is rotated for removal of material by a tool, which attachment comprises a curved track for mounting adjacent the workpiece location of the machine, a tool carrier mountable on the track and means for moving the tool carrier along the track.

1. A shaping machine comprising means for rotating a workpiece, a tool carrier, for carrying a tool to shape the workpiece, a curved track along which the tool carrier is moveable and means for moving the tool carrier along track.

2. A shaping machine as claimed in claim 1 wherein the track is part-circular.

3. A shaping macine as claimed in claim 2 wherein the track is semi-circular.

4. A shaping machine as claimed in any prececing claim wherein the track comprises a rack and the tool carrier comprises a pinion, engaging the rack so that rotation of the pinion drives the carrier along the track.

5. A shaping machine as claimed in claim 4 wherein a reversible electric motor is provided connected to rotate the pinion.

6. A shaping machine as claimed in claim 5 wherein the electric motor is controlled to run at infinitely variable speed by a control unit.

7. A shaping machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

8. An attachment for a lathe comprising a curved track for mounting to extend longitudinally in the lathe bed adjacent the workpiece location, a tool carrier mountable on the track and means for moving the tool carrier along the track.

9. An attachment as claimed in claim 8 wherein the rack, tool carrier and/or means for moving the tool carrier are as defined in any one of claims 2 to 6.

10. An attachment for a lathe substantially as

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Shaping machine The invention relates to shaping machines such as lathes and to fittings or attachments for such machines. The normal method used for machining a curved object e.g. a sphere is by a highly skilled operator "stepping-out" the curvature of the surface and then finishing with a series of fine cuts working to the fit of a gauge or template, or by use of a normal lathe but with a template and copying attachment fitted. This is a refinement of the first method which removes some of the dependence on the operator's skill but because of the characteristics of the machine is still a stepping-out operation. A third method is by use of a numerical control or computer control machine. The principle is still the same as in the first two methods but the steps are infinitely small. The present invention provides a shaping machine, e.g. a lathe, comprising means for rotating a workpiece, a tool carrier, for carrying a tool to shape the workpiece, a curved track along which the tool carrier is moveable and means for moving the tool carrier along the track. The invention includes a shaping machine as claimed in claim 1 wherein the track is part-circular. The track may be part circular, e.g. semi-circular, or may be a non-circular curve, e.g. semi-elliptical. The use of a semi-circular track enables the machin ing of a spherical shape. Preferably, the track comprises a track and the tool carrier comprises a pinion, engaging the rack so that rotation of the pinion drives the carrier along the track. Preferably, a reversible electric motor is provided connected to rotate the pinion. Such an electric motor may be controlled to run at infinitely variable speeds by a control unit. The invention is applicable generally to machines in which a workpiece is rotated for the removal of material by a tool. Machines of this type include lathes and also vertical turning and boring machines. The invention will be illustrated by the following description of a preferred embodiment with refer ence to and as illustrated in the accompanying drawing, which is a perspective view from the side of a lathe according to the invention. The lathe shown is a metal-working lathe adapted for machining spheres by the mounting of an attachment in the normal lathe bed on the lathe saddle. The attachment consists of a guide track attached ;to a base plate 2 which is itself attached to the saddle 3 of the lathe. An accurately machined rack 4 is contained on the outer circumference of the track. Mounted on the track is a tool carrier 5, integral with which is an electric motor 6 which drives, through a gear box 7, a pinion (not shown) which engages with the rack 4 on the outer circumference of the track. The motor is governed by a specialised control unit 8 which gives an infinitely variable speed control and therefore drives and controls the movement of the tool carrier around the track at a speed which can be varied to suit the changing diameter and surface speed of the sphere. Metal cutting tools (not shown) are fastened in the tool posts 9 on the tool carrier and by varying the length of tool shank a range of diameters can be cut with any one guide track. A series of tracks can cover a wide range of sizes. In normal cutting procedure on a standard lathe the contour is produced by a combination of the longitudinal movement of the machine saddle through rotation of a longitudinal lead screw and the transverse movement of the tool post and cutting tool through rotation of another lead screw at the top of the saddle. With the attachment which is the subject of this invention shown in the drawing neither of these are used. Once the attachment is fixed in a correct setting on the saddle, the workpiece is rotated through the headstock in the normal way but all cutting tool movement is controlled by the attachment and this movement is in a truly circlar path thus producing a smooth and true sphere. The invention includes an attachment for a shaping machine in which a workpiece is rotated for removal of material by a tool, which attachment comprises a curved track for mounting adjacent the workpiece location of the machine, a tool carrier mountable on the track and means for moving the tool carrier along the track. CLAIMS

2. A shaping machine as claimed in claim 1 wherein the track is part-circular.

3. A shaping macine as claimed in claim 2 wherein the track is semi-circular.

10. An attachment for a lathe substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

11. An attachment for a shaping machine in which a workpiece is rotated for removal of material by a tool, which attachment comprises a curved track for mounting adjacent the workpiece location of the machine, a tool carrier mountable on the track and means for moving the tool carrier along the track.