Patent GB-1506448-A (GB)
Title: Indexing mechanisms and machine tools incorporating the same
IPC: B23Q5/50
Filed: 1975-08-04
Abstract: 1506448 Grinding; linear indexing CAPLIN ENG CO Ltd 30 July 1976 [4 Aug 1975] 32584/75 Headings B3D and B3B An indexing mechanism for affecting stepwise advance between a workpiece and a tool or workpiece of a machine tool by an indexing stroke of predetermined length comprises first and second displaceable members 10, 11 interconnected for displacement, in turn, alternately towards and away from each other, the extent of the displacement determining the indexing stroke, means 22 to adjust the extent of the stroke, and means 14, 16 operable to selectively immobilize each member during displacement of the other. The indexing stroke may be curved or linear and in a vertical, horizontal or other direction. As described, the mechanism effects linear vertically downward movement of a silicon rod 3 which is to be cut into slices or wafers by an annular saw 4, as described in Specification 1,319,768. The indexing mechanism is mounted in slideways 5 of a carrier 6 fixed to a plate 7 of an arm 8 of a feed mechanism 9. The first and second displaceable members consist of slide blocks 10, 11 having a dovetail configuration to engage the slideway 5, the block 10 being below block 11 and having a bore 10d in which a mount for the rod 3 to be sliced is held by a bolt 18. One or both of the dovetail surfaces 10a, 11a of the blocks 10, 11 has a releasable primary clamp 14, 16. The clamp 14 is similar to the clamp 16 and consists of a gib strip which is located in a slot in the surface 10a and can be pressed against the slide 5 to clamp the block 10 by an hydraulic actuator having a thrust strip 12d and sealing strip 12c retained in a chamber 12c by clips 12e. Fluid pressure supplied to the chamber through a port 12f urges the thrust strip against the gib strip 14 to clamp the block 10 to the slide 5. A secondary clamp comprising springs 17 acts to urge the gib strip 14 against the slide 5 with a lower pressure than that applied by the hydraulic actuator to hold the block against undesired movement. A pin 15 prevents axial movement of the gib strip 14 relative to the slide block. The slide block 11 is formed with a stepped passage having a portion 11d receiving a linear actuator consisting of a cylinder 19 and a double acting piston 20 having rods 20a, 20b. Rod 20a is connected to a pillar 10e on the slide block 10 and movement of the piston to the right (Fig. 5) is limited by an end plate 21. Movement of the piston to the left is limited by engagement of the rod 20b with a reduced portion 22a of an index stop 22, a large diameter portion 22b of which is axially slidable in a portion 11e of the stepped bore 11d. Rotation of the stop is prevented by a key 24 engaging a keyway 11f in the portion 11e, play between the key and keyway being prevented by a spring- pressed tensioner block 25 slidable in an enlarged keyway 25a, A reduced portion 22c of the index stop 22 is in screw threaded engagement with the hub 28a of a worm wheel 28 engaging a worm 33 fixed to a manually rotatable shaft. Rotation of the shaft by a knob axially displaces the index stop to determine the length of the index stroke between the slide blocks 10, 11 upon actuation of the linear actuator 19, 20. Graduations on the knob and on a dial 39, or a linear transducer engaging the end 22d of the index stop, indicate the length of the indexing stroke. The blocks can be moved at fast or slow speed, in unison, along the slide by an actuator 44 having a rod 44a connected to the block 11 to initially position the rod to be cut. After cutting of an initial slice, the mechanism is automatically controlled by an electro-hydraulic circuit. During cutting, both gibs 14, 16 of the blocks are clamped to the slide. Thereafter, the gib 16 of the upper block 11 is released, and the actuator 19, 20 operated to draw the block 11 down towards block 10. The gib 16 is then reclamped to the slide, the clamp 14 of the lower slide released and the actuator 19, 20 operated to move the block 10 away from block 11 to effect the indexing stroke, the gib of block 14 again being operated to clamp the block to the slide for the cutting operation.