Patent GB-670500-A (GB)
Title: Improvements in copying lathes
IPC: B23Q35/18
Filed: 1948-08-21
Abstract: 670,500. Copy-turning. B.S.A. TOOLS, Ltd., and PETZOLDT, F. G. Aug. 20, 1949 [Aug. 21, 1948], No. 22087/48. Class 83 (iii). A hydraulically - controlled copying lathe comprising a saddle and a crossslide on the saddle for carrying cutting means has stylus means carried by the cross-slide and movable in contact with a former so as to be tiltable in two directions at right angles, tilting of the stylus in one direction causing movement of the slide at right angles to the line of movement of the saddle, and in the other direction causing an interruption in the movement of the saddle together with a contemporaneous movement of the slide again in a direction at right angles to the line of movement of the saddle but opposite to its previously mentioned movement. The saddle 10, Fig. 1, has secured thereto a cylinder 12 which is movable by fluid pressure applied to its ends in conjunction with a stationary piston 13 secured to the machine bed. Admission and exhaust of this fluid is controlled by a valve 19 loaded by a spring 20 at one end, and formed at its other end with an abutment 21. The latter co-operates with a stop 22 carried by an arm on a control bar 24 formed with rack teeth and slidable along the bed by a pinion 26 which is geared to the machine spindle through a variable gear train. The pinion 26 is driven by a friction clutch which is adapted to slip when the control rod 24 is held against sliding movement by a plunger 83 controlled as described below. Cross-slide operation. The cross slide 33 has secured at the rear end a cylinder 36 and valve gear 39. The co-operating piston 37 of the cylinder is fixed to the saddle by a bracket 96, Fig. 2. A replica 50, Figs. 2 and 3, of the workpiece to be produced, is arranged at the rear of the saddle to be engaged by a stylus 47. The latter is pivoted at 48 to a lever 51 which is in turn movable in a direction at right angles to the first movement about a pivot 52 in a bracket 53 on the cross slide. The lower end of the stylus lever has a roller 46 engaging a transverse slot on the end of the valve member 43 which controls admission and exhaust of fluid for the cross-slide movements. In addition the stylus lever may be rotated about pivot 48 through a roller 55 on an extension 54 of the lever contacting a short lever 56 pivoted at 57, the forward end of which carries a roller 61 engaging an adjustable stop-bar 62 formed with a protruding cam surface at its inner end. The lever 56 is carried in a swivel member 58 on a bracket 59 secured 'to the cross slide and, adjacent the roller 61 is provided with an upstanding portion 60 which may strike the side of the stop-bar 62 and thus rotate the stylus and arm 51. The latter carries a stud at its lower end to move a valve member 65 and allow fluid to pass to a piston 71 actuating a rocker 75 and valve 45 and additionally moving a lever 77 which, through cross shaft 78, Fig. 2, and lever 82, Fig. 1, depresses plunger 83 to stop sliding motion of the control bar 24. Operation. The control bar 24 is traversed at the desired rate of feed to the left, Fig. 1 by the feed gearing and operates valve 21 for saddle movement. The front tool 86, Figs. 2 and 3, effects turning during this movement to the diameter of the pattern. The stops 62 are previously set to the position at which they rock the stylus and lever 51 to stop the saddle feed for shouldering. The rear tool 90 is used for L.H. shoulders and grooving and as the valve 43 is operated by lever 75 to start the transverse movement of the tool the cam surface on the lower face of the stop rod operates through roller 61, lever 56 and roller 55 further to open valve 43 and thus increase the rate of approach of the tool until it is about to start cutting. When abutment 60 moves clear of stop 62 the stylus and arm 51 assume a vertical position and the valve members are released and spring-returned. The valve 43 admits fluid to the L.H. end of cylinder 36 causing the front tool to approach the work again to cut a new diameter represented by the next section of the pattern, the saddle contact bar being released by reverse rotation of lever 77 and upward motion of pin 83. In a modification the saddle is driven by a lead screw with a friction clutch interposed in the drive thereto, the clutch is operated from the stylus to stop the saddle during surfacing movements by mechanism similar to that described above but including a switch and a solenoid for operating the clutch. In this arrangement a cut-off sleeve-valve is used with a plunger member, tilting of the stylus in one direction operating the sleeve while tilting at right angles thereto moves the plunger.