GB2092935A - Spark erosion machines - Google Patents

Abstract

An orbital device, in or for a spark erosion machine, which includes a housing (11) connected or connectable to the electrode position control mechanism of the machine and a carrier (12) to which an electrode and holder may be connected by means of block (13), wherein the carrier (12) and housing (11) are interconnected by bearings (22 and 35) and ring (21) to permit freedom of movement of the carrier (12) with respect to the housing (11) in any direction at right angles (or nearly so) to the direction of electrode feed, the housing (11) and the carrier (12) being interconnected by position control means (30, 31 and 33) arranged so that the carrier (12) may be displaced laterally with respect to the housing (11) and, alternatively or simultaneously, moved in an orbital path. <IMAGE>

Description

SPECIFICATION Spark erosion machines This invention relates to spark erosion machines and more particularly to an orbital device for applying an orbital motion to the electrode of a spark erosion machine. The orbital device may be built into the electrode position control structure of a spark erosion machine or it may take the form of an attach mentwhich may be inserted in the electrode position control structure of an existing spark erosion machine.

The present invention consists in an orbital device, in or for a spark erosion machine, which includes a housing connected or connectable to the electrode position control mechanism of the machine and a carrier to which an electrode and holder may be connected, wherein the carrier and housing are interconnected by bearings to permit freedom of movement of the carrier with respect to the housing in any direction at right angles (or nearly so) to the direction of electrode feed, the housing and the carrier being interconnected by position control means arranged so that the carrier may be displaced laterally with respect to the housing and, alternative ly or simultaneously, moved in an orbital path.

The position control means may include cooperating surfaces arranged so that when an axial force is applied to one surface, the carrier is displaced laterally, at least one of the surfaces being rotatable to move the carrier in an orbital path.

In one form of the invention the position control means includes a co-axial bush mounted for rotation and having an inclined bore receiving a cylinder, the arrangement being such that relative axial movement between the cylinder and bush causes lateral displacement of the carrier and rotation of the cylinder and/or bush causes orbital movement of the carrier.

In an alternative form of the invention, an axial shaft mounted for lateral movement and having an inclined end face is arranged so that when an axial force is applied to the end force of the shaft the shaft is displaced laterally to move the carrier laterally, the mounting of the shaft being rotatable axially with respect to the device so as to determine the direction of lateral movement of the shaft and to effect orbital movement of the carrier.

In the accompanying drawings: Figure 1 is a vertical section taken through the axis of one form of orbital device according to the present invention, Figure 2 is a view from the left hand side of Figure 1, partly in section, Figure 3 is a vertical section taken through the axis of an alternative form of orbital device according to the present invention, and Figure 4 is a horizontal section taken on line 4-4 of Figure 3.

In carrying the invention into effect according to one convenient mode by way of example, the accompanying drawings show an orbital motion attachment which includes a housing 11 securable to the electrode position control structure of an existing spark erosion machine and an electrode carrier 12 having a dovetail grooved block 13 by means of which an electrode may be connected to the carrier 12.

The housing 11 and the carrier 12 are constructed an interconnected in the following manner such that the carrier 12 may be moved horizontally (or nearly so) in any direction from its central position as shown in the drawings.

The housing 11 includes a circulartop plate 14 secured to a control boss 15 and to a cylindrical member 16 having an inwardly extending annular flange 17.

The carrier 12 has a circular bottom plate 18 having a horizontal bore 19 ans is secured by a clamping ring 20 to an annular ring 21 forming an outwardly extending flange extending over the inwardly extending flange 17. A circular series of spring-loaded ball bearings 22 is provided between the upper surface of ring 21 and the lower surface of top plate 14 and a further series of ball bearings 35 is provided between the lower surface of ring 21 and the flange 17.

With the arrangement thus far described it will be appreciated that the carrier 12 is free to move for a limited distance in any horizontal direction relative to the housing 11, and the carrier 12 can also perform small movements out of the horizontal plane against the spring-loading of the ball bearings.

Bearings 23 are provided in bore 19 and receive a shaft 24 connected at each end to the lower end of an arm 25 constrained at its upper end 26 in a slot 27 in the cylindrical member 16 so that the shaft 24 is suspended from the slots 27 by the arms 25.

The boss 15 accommodates a bearing 28 for a central vertical shaft 29 keyed at its lower end to a drive cylinder 30 arranged with its axis at an angle with respect to the axis of shaft 29. The cylinder 30 is mounted by means of bearings 31 in an inclined bore 32 in a bush or collar 33 itself free to rotate coaxially with shaft 29 by means of bearings 34 mounted in the carrier 12.

With this arrangement, when the shaft 29 is moved downwardly from its uppermost position shown in the drawings, the drive cylinder 30 acting on the bush 33 will cause the carrier 12 to be moved horizontally to the right sliding on the shaft 24 and bearing 22 and 35 The carrier 12 can thus be offset from its central position by an amount dependent upon the amount of vertical movement of the shaft 29.

If the shaft 29 is rotated through 90 from the position shown in the drawing, as may be indicated by a calibrated wheel 37 secured to shaft 29 and a position 36 secured to the housing 11, the bush 33 will also be rotated through 90 and any subsequent vertical movement of the shaft 29 will cause the carrier to be moved in a direction at right angles to the plane of the paper, the shaft 24 performing a swinging movement about the upper ends 26 of the arms 25.

If the shaft 29 is rotated to any other angular position, then vertical movement of the shaft 29 will cause a combination of the above two movements, that is to say horizontal sliding of the carrier 12 on the shaft 24 and near horizontal swinging with the shaft 24.

It will be appreciated that vertical axial reciprocation of the shaft 29 without rotation will cause horizontal (or near horizontal) reciprocation of the carrier 12 in a direction determined by the angular position of shaft 29 in relation to the housing 11.

Alternatively, continuous rotation of the shaft 29 without axial reciprocation (but after displacement of the carrier from its central position shown in the drawing) will cause the carrier 12 to orbit in a circle whose radius is determined by the vertical position of the shaft 29.

Combined vertical axial reciprocation and rotation of the shaft 29 will thus cause the carrier 12 and any electrode connected to it to perform a complex motion of combined orbiting and reciprocation which has many useful applications in the carrying out of spark erosion processes.

Various control devices may be provided to provide intermittent and/or continuous rotation and/or vertical movement of the shaft 29 to achieve a desired motion of the electrode.

Figures 3 and 4 show an alternative form of orbital device in which, in similar manner to the embodiment of Figures 1 and 2, the carrier 12 is mounted upon a shaft 24 and has an annular ring 21 supported between series of ball bearings 22 and 35.

However, a different form of position control means is used to control movement of carrier 12 relative to the housing 11.

A control rod 41 is connected to a cam 42 arranged so that when the rod 41 is moved to the right with respect to Figure 3 the cam 42 urges axially downardly a series of three balls 43, the lowermost of which bears upon the inclined end face 44 of a shaft 45 mounted for rotation in bearings in the carrier 12 and thus imparts a thrust to shaft 45 and carrier 12 towards the left hand side of Figure 3. The upper end of shaft 45 is connected to two yoke arms 46 (Figure 4) mounted for sliding movement upon horizontal rods 47 thereby permitting movement of shaft 45 with carrier 12 to the left.

The ends of the rods 47 are mounted in an annular member 48 connected to disc 49 which is connected to a co-axial pinion 50 arranged to be rotated by a worm 51. Rotation of worm 51 thus rotates shaft 45 and its inclined end face 44 and thus determines the lateral direction in which carrier 12 will be moved in response to movement of control rod 41. Once the carrier 12 has been offset from its central position as shown in Figure 3 by means of movement of rod 41, continuing rotation of worm 51 will cause the carrier 12 to orbit around the axis of the housing.

In similar manner to the first embodiment, combined reciprocation of rod 41 and rotation of worm 51 may be used to cause the carrier 12 and the electrode connected to its to perform any desired complex motion of combined orbiting and reciprocation.

In the embodiment shown in Figures 3 and 4, the top of the housing 11 is provided with a dovetail fitting 52 to facilitate the connection of the device to the electrode position control structure of a spark erosion machine.

Claims (5)

1. An orbital device, in or for a spark erosion machine, which includes a housing connected or connectable to the electrode position control mechanism of the machine and a carrier to which an electrode and holder may be connected, wherein the carrier and housing are interconnected by bearings to permit freedom of movement of the carrier with respect to the housing in any direction at right angles (or nearly so) to the direction of electrode feed, the housing and the carrier being interconnected by position control means arranged so that the carrier may be displaced laterally with respect to the housing and, alternatively or simultaneously, moved in an orbital path.

2. A device as claimed in claim 1, wherein the position control means includes co-operating surfaces arranged so that when an axial force is applied to one surface, the carrier is displaced laterally, at least one of the surfaces being rotatable to move the carrier in an orbital path.

3. A device as claimed in claim 1 or 2, wherein the position control means includes a co-axial bush mounted for rotation and having an inclined bore receiving a cylinder, the arrangement being such that a relative axial movement between the cylinder and bush causes lateral displacement of the carrier and rotation of the cylinder and/or bush causes orbital movement of the carrier.

4. A device as claimed in claim 1 or 2, wherein an axial shaft mounted for lateral movement and having an inclined end face is arranged so that when an axial force is applied to the end face of the shaft the shaft is displaced laterally to move the carrier laterally, the mounting of the shaft being rotatable axially with respect to the device so as to determine the direction of lateral movement of the shaft and to effect orbital movement of the carrier.

5. An orbital device substantially as described with reference to the accompanying drawings.