Patent GB-697259-A (GB)
Title: Improvements in hydraulic copying lathes
IPC: B23Q35/18
Filed: 1951-05-17
Abstract: 697,259. Copy-turning. FISCHER AKT.-GES., G. May 17, 1951 [May 17, 1950], No. 11603/61. Class 83 (iii). Hydraulic copying lathes in which a tracer point operating in conjunction with a control piston has means which scans patterns on the machine frame and comprises valve means which are brought by hand into operating position for initiating the first turning operation, and which are successively operated automatically by tripping members to control the turning cycle, at least two patterns being used in succession and a change in the distance between the tool and the point of contact of the tracer point with the pattern being effected to increase the amount of cut. The work 4 is held between a headstock 2 and tailstock 3 on a bed 1 and is rotated by means, not shown. Successive cuts represented by broken lines 101 ... 103, are made by a tool 7 carried by a crossslide 6 which is in turn mounted on a longitudinally movable saddle 5. The latter is moved by rack and pinion gear 29, 28, the former secured to the bed, and the latter, with worm gearing and clutch-controlled driven pinions 18, 19, being mounted on the saddle. The drive to the clutch shaft 17 is not shown. Operation of the clutch 20 to give feed, dwell, or return movement to the saddle is effected through a spring- returned rod 22, a hinged plate 24, and a stepped cam 91 ... 93, the latter being carried by the cross-slide. Movement of the cross-slide 6 is effected by hydraulic-pressure fluid from a pump 14 which passes through a line 16 to a differential piston 13. A reducing valve (not shown), in the passage 97 of the piston maintains a constant pressure. The cross-slide forms the cylinder, moving over the piston 13, and cutting movements of the tool are controlled by a spring-pressed leak-valve 50 in the slide which bears against the arm 68 of a pivoted tracer 9, the point of which follows a pattern 8 carried by the lathe bed 1. An auxiliary scanning lever 39, also pivoted to the slide 6, has one end engaging the tracer arm 68 and the other end contacting stops 37, 38 on the saddle to limit the " in " and " out " movements of the cross-slide. The lever 39 may also be moved to halt the feed movement of the cross-slide by a lug 73 on a lever 70 pivoted about the same axis as lever 39 and pressed by a spring 71 so that a roller 72 adjacent the lug 73 engages a bar 36 moved parallel to itself by mechanism described below. Construction of tracer.-The tracer point 100 moves along a dovetailed guide 88, Fig. 6, in the end 9 of the arm 68. The point is normally retained in its lower position by a spring 98, a bar 99 contacting an external ledge. When hydraulic pressure is applied through a flexible line 47, however, a piston 49 contacts the bar 99 and raises it into contact with a pre-set stop screw 59. The difference between the upper and lower positions of the tracer governs the amount of the cut taken in two successive passes over the same pattern. Operation. Initiation of the cycle and automatic control is effected from valves 32, 52, the latter consisting of a rod 42, Fig. 8, with a handknob 79 at one end and flattened valve parts 112 at the other end controlling pressure and exhaust to the various passages. The rod 42 is urged by a spring 86 to the right and carries a plate 81 with stops 83, 84 contacting a cooperating stop 43 on the saddle for rotating the valve. A boss integral with the plate 81 is provided with three notches into which a spring- pressed ball 105 is urged in turn fixing the indexed positions of the valve. A further plate 55 is rotatable on the rod 42 and co-operates with a stop plunger 53 on the slide and a rotatable stop 40 on the saddle. A lug 95, Fig. 1, on the plate 55 engages, in certain positions, a stop lug 82 on the plate 81. With the slide 6 fully withdrawn (lever 39 contacting stop 37), the saddle in the right-hand position and valve 52 set to allow pressure to pass through passage 60 to stopplunger 53 (the position of the parts after a previous cycle), the pump 14 is started and fluid passes to piston 13 to move the tool-slide towards the work. Line 74 is also under pressure which passes to valve 32 and to piston 34 which moves the bar 36 to the left in a direction parallel to itself against spring- pressure 94. As the tool slide moves towards the work the hinged plate 24 is on the middle tip of the slide and there is no saddle movement. Stop plunger 53 has rocked plate 55 so that this contacts stop 40 which moves bar 36 to the right, allowing lever 70 to rock and move lever 39 clockwise to open leak valve 50 and stop the in-feed. Knob 79 is then pressed in so that valve 42, Fig. 8, may be turned anticlockwise to bring plate 81 into the first indexed position. Stop 82 on plate 81, Fig. 1, is thus brought against stop lug 95 on plate 55. Bar 36 again moves to the left, allowing a spring 51 to close the leak valve 50 and in-feed movement of the tool-slide recommences. Valve 52 is now set so that pressure may pass to line 89 and flexible pipe 90 to a device 107, Fig. 4, for rotating the pattern carrier 109, and a plunger of this device moves against a spring to bring a pattern 8 into position for engagement with the tracer 100 (second pattern 108 is shown in the operation position in Fig. 4). Hinged plate 24 moves on to step 91 as the tool approaches the work and saddle-feed is operated to move tool to left, tool is brought under control of tracer at this stage and first turning operation proceeds. An adjustable stop 11 on a rod carried by the machine bed determines the extent of this operation, a lever 30 on the saddle on contacting this stop is thrown over to the right and operates valve 32 so that fluid no longer flows to plunger 34, bar 36 moves again to the right, allowing lever 70 to rotate and stop feed-movement of slide as above by opening valve 50, and the tracer point is at the same time moved clear of the pattern. As the valve 50 is opened wider the motion of the slide 6 is reversed and it returns until the lever 39 contacts the stop 37. Stop-lug 43 pivots back against spring pressure when the plate 81 returns past it and is ineffective to rotate it. Saddle is first halted and then return movement is started when the hinged plate 24 reaches step 93. Return movement of the saddle continues until lever 30 thereon strikes a further adjustable stop 12 on the bar 10. Valve 32 is then again set over to allow pressure to pass to plunger 34 to move bar 36, close valve 50, and re-start the in-feed movement of the tool-slide. The operations then follow similarly to those above except that lug 83 on plate 81 contacts the ratchet stop 43 to index the plate one notch so that valve 52 now allows pressure to pass to the plunger in the tracer-head to move the tracer up against the set stop. Pressure to the rotatable pattern carrier is also cut off so that a new pattern 108 is brought into position, Fig. 4. The action then proceeds as for the first cut. Finally, the plate 81 is indexed a further notch by lug 84 and stop 43 on the third in-feed movement to cut off pressure to the tracer-head so that the tracer point moves back the distance of the final cut; the same pattern 108 is used for this cut. The parts are automatically returned to the initial position described above where the slide stops in the retracted position. Valve 52 may be initially set by the knob 79 to give only two cutting strokes if required.