GB2065515A - Method and machine for forming a chamfer or groove on a workpiece - Google Patents

Abstract

For producing, for instance, a chamfer (36) on the pre-worked edge (26) of a glass (4) of a watch- casing, the glass is pressed against the end of the spindle (19) of the machine, by a lever (20), without paying attention specially to the fact the glass is perfectly centered on the spindle. The surface (26) of the glass (4) is used as a copying templet by maintaining this surface (26) applied against a rotatable disc (27) forming an abutting roller. The grinding-wheel (3) is displaced axially, and the front face of the disc (27) is provided with the recess (34) to receive the grinding-wheel (3) during the axial movement thereof. The lateral wall (35) of the recess (34) is frusto-conical so as to maintain to the disc (27) rigid. In another arrangement a groove is formed in the workpiece. <IMAGE>

Description

SPECIFICATION Working method and machine for carrying out this method The present invention relates to a working method, by copying, of a workpiece a surface of which is already pre-worked, as well as to a machine for carrying out this method.

The purpose of the invention is to simplify the working and the machine by using the very preworked surface of the workpiece as a copying templet that permits moreover to place the workpiece on the spindle of the machine without having to center it precisely.

The drawing shows, by way of example, one embodiment of the invention and a modification of a workpiece represented in work.

Figure 1 is an elevational view of the two portions, separated, of a machine serving to grind the edge of watch glasses made of extra-hard material.

Figure 2 is a profile view of the right portion, seen in Fig. 1, of the machine.

Figure 3 is a plan view of this machine, the two portions of which are in their working position.

Figure 4 is a view of a detail at a larger scale.

Figure 5 is a view of a portion of this detail at a still larger scale, and Figure 6 is a sectional view of a modification of a workpiece.

The machine as illustrated comprises two distinct portions, generally designated by 1 and 2, respectively, the first one of which serves to drive the cutting tool, a diamond grinding-wheel 3 in the example as represented and, the second one to the driving of the workpiece, a watch glass 4 in the present case, on the pre-worked edge of which it is contemplated to provide a chamfer.

The portion 1 of the machine comprises a stationary frame 5 carrying a crossed slides generally designated by 6, on the upper part of which is mounted a sliding member 7 carrying a quill 8 the shaft 9 of which, carrying the grinding-wheel 3, is driven by a motor 10 by means of a transmission belt 11.

The motor 10 thus drives the grinding-wheel 3.

The sliding member 7 carries moreover, mounted on a bracket 12, a motor 13 driving a crank 14 the crank-shaft 15 of which is moved in a rectilinear slide 16. The motor 13 thus produces a go-and-back movement, in the sense of the arrow 17 of Fig. 1, of the quill 8 and of the grinding-wheel 3, which is necessary when it is matter of working extrahard materials such as Corindon, sapphire, etc.

The portion 2 of the machine comprises a quill 18 against the end of the spindle 19 of which is applied the work-piece 4 by means of a lever 20, articulated at 21, and which is submitted to the action of a control shaft 22 exerting thereon a pull.

The quill 18 is carried by an oscillating arm 23 articulated at 24 on the frame 25 of this portion of the machine and which, in its working position, is slightly inclined, as shows Fig. 2, thus maintaining, by its own weight, the glass 4 bearing, by its preworked edge 26 (Figs. 4 and 5), against an abutting member constituted by a circular disc 27, of the same diameter as the grinding-wheel 3, mounted on a shaft 28 rotating in a headstock 29. The spindle 19 on which is mounted the workpiece is driven by a motor 30 through the intermediary of two transmission belts 31 and 32.

So as to permit the axial go-and-back movement of the grinding-wheel 3 indicated by the arrow 33 of Fig. 5, without the said grindingwheel encounters the disc 27 constituting an abutting roller, the front face of this disc, facing the grinding-wheel 3, is provided with a recess 34 the lateral face 35 of which (Figs.

4 and 5) is frusto-conical so as to maintain the rigidity of the disc 27. The angle made by the frusto-conical face 35 of the recess 34 of the disc 27 depends from the inclination of the chamfer 36 one wants to realize, by means of the grinding-wheel 3, on the edge 26 of the glass 4.

Owing to the present arrangement, one uses the very pre-worked surface of the workpiece as a copying templet, that is a great simplification. Moreover, one prevents one of the main difficulties of any operation comprising successive stages, which consists in placing on the machine the workpiece in a rigorously exact position. As a matter of fact, a glass 4 can be placed on the spindle 19 in any position, its centering with respect to the spindle playing no role so far as the precision of the working is concerned, since the working is effected while using a surface of the very workpiece as a reference. The outline of the worked surface, here the chamfer 36, corresponds automatically to the outline of the pre-worked surface, here the edge 26 of the glass 4.

The working thus realized can be different from a chamfer and constitutes, for instance, a groove, as groove 37 of glass 38 of Fig. 6 provided in the preworked edge 39 thereof.

This edge 39 serves as a reference surface or as a templet for the working of the groove 37 the same way as in the case of the chamfer 36 of the glass 4. Here, the grinding-wheel will not have to effect an axial go-and-back movement.

Obviously, the method and the machine according to the invention could serve to the working of any workpiece needing an operation comprising successive steps and not only to the work of watch-casings.

Moreover, the workpieces can be other than circular, but be shaped, quadrangular for in stance, the pre-worked surface being able to be made of segments of a plane surface separated by edges. In this case, the experience shows that more the axis of the grindingwheel is inclined with respect to the axis of the spindle, more it is necessary to reduce the diameter of the abutting disc.

Claims (11)

1. Method of working, by copying, of a workpiece the surface of which is already preworked, wherein one uses the said pre-worked surface as a copying templet.

2. Method according to claim 1, wherein one drives in rotation the workpiece while maintaining it, by its pre-worked surface, bearing against a bearing member and effects the working by means of a rotatable cutting tool in such a way that the outline of the worked surface corresponds to the outline of the pre-worked surface.

3. Method according to claim 2, wherein one realizes, by means of a grinding-wheel, a chamfer on the pre-worked edge of the workpiece.

4. Method according to claim 3, wherein one uses, as an abutting member, the edge of a rotatable circular disc, forming a roller, one of the faces of which is provided with a recess giving passage, at least partially, to the chamfering grinding-wheel.

5. Machine for carrying out the method according to claim 2, comprising a stationary abutting member, a quill, carried by a movable support, on the spindle of which is secured the workpiece, means permitting to apply elastically the pre-worked surface of the workpiece against the said abutting member, and a rotatable cutting tool, which is stationary, cooperating with the workpiece.

6. Machine according to claim 5, wherein the support of the quill carrying the workpiece is constituted by a bed articulated on the frame of the machine, and which maintains, by its own weight, the workpiece applied against the abutting member.

7. Machine according to claim 5, wherein the abutting member is constituted by a rotatable circular disc forming a roller, the cutting tool being constituted by a grinding-wheel.

8. Machine according to claim 7, wherein the axial face of the said disc forming a roller is provided with a recess giving passage, at least partially, to the grinding-wheel.

9. Machine according to claim 8 for the working of workpieces made of extra-hard material, by means of a diamond grindingwheel, wherein the grinding-wheel is submitted to an axial go-and-back movement, combined with its rotatable movement, during which it engages partially the recess of the abutting disc.

10. A method of working, by copying, of a workpiece the surface of which is already pre-worked, substantially as herein described.

11. A machine for working, by copying, of a workpiece constructed and arranged substantially as herein particularly described with reference to Figs. 1 to 5 of the accompanying drawing.