Patent GB-630365-A (GB)
Title: Improvements in or relating to duplicating machine tools
IPC: B23Q35/10
Filed: 1945-02-02
Abstract: 630,365. Copying-mechanism for grinding-machines. AKT.-GES. DER EISEN-UND STAHLWERKE VORM G. FISCHER. Feb. 2, 1945, No. 2694. Convention date, Jan. 14,. 1944. [Class 60] [Also in Group XXII] In a metal cutting or like machine tool for copying, having longitudinal and transverse slides controlled by a tracer and pattern, transverse movements imparted by the pattern are used to influence the longitudinal movement so that the speed of the latter is varied or reversed according to the inclination of the pattern in the longitudinal direction. In one form a lathe comprises a bed 1 (Fig. 1) having a headstock 2 and an adjustable tailstock 3 for the work 11. The tool 10 is carried by a transverse slide 7 mounted on a longitudinally movable saddle 6, the slide 7 also carrying a rigid tracer 8 engaging a fixed pattern 9. A compression spring 12 maintains the tracer in contact with the pattern and tends to feed the tool to the work. An electric motor 13 is mounted on a slide 14 movable along the guides 5 for the saddle 6 by the engagement of a pinion thereon, driven from the motor by worm gearing 16, with a fixed rack 17, and the slide is coupled to the saddle by a link 18 pivoted at 18<SP>1</SP> to a bell crank 19 pivoted at 18" on the saddle. The other limb of the crank engages a slot on the tool slide 7. In operation, as the slide 14 is traversed towards the headstock 2 it pushes the saddle in the same direction and if the pattern profile recedes as at A the spring 12 will feed the slide 7 inwardly, thus rocking the crank 19 about the pivot 18<SP>11</SP> and causing the saddle to be traversed at a higher speed than the slide 14. When the pattern is parallel to the work axis the slide 7 and crank 19 have no motion relatively to the saddle, which then moves at the same speed as the slide 14, but if the pattern profile advances as at B, the tracer will move the slide 7 outwardly and the resultant rocking of crank 19 will slow down the saddle traverse relatively to the slide 14. If the tracer encounters a surface perpendicular to the work axis, further traverse of the saddle will be stopped and the crank 19 will be rocked to move the slide 7 outwardly until the perpendicular surface has been surmounted whereas a re-entrant surface on the pattern will rock the crank to such an extent that traverse of the saddle will be reversed and the tool will reproduce the re-entrant surface on the work. In a modification applied to a milling machine the work 34, Fig. 2, is carried by a longitudinal slide 24 mounted on a transverse vertically movable saddle 22 urged upwardly by a hydraulic cylinder 23. The slide 24 carries a tracer 32 engaging a fixed pattern 33 which controls fluid supply to cylinder 23 to move the saddle up or down and the slide also carries a motor 25 driving a pinion 27 through a worm 26. The pinion engages a rack 28 movable on the saddle 22 and meshing with a pinion 29 on the saddle which also engages a rack 30 fixed to the bed at 51. If the pattern surface is parallel to slide 24, the pinion 29 and rack 28 will remain stationary and the pinion 27 will roll along rack 28 to impart a normal rate of traverse to the slide 24, but vertical movement imparted by the pattern to the saddle 22 causes the pinion 29 to roll on the fixed rack 30 and thus move the rack 28 to increase or decrease the speed of traverse according to the direction of vertical movement. This mechanism may also be applied to a lathe. In another lathe similar to that shown in Fig. 1, the motor 13 is mounted directly on the saddle 6 and rotates the pinion engaging the rack 17 through a differential gear whose planet carrier is connected by gearing to a pinion meshing with a rack on the transverse slide 7 so that in and out movements of the latter will vary, stop or reverse the drive for the saddle in conformity with the pattern profile. In a modified form of this mechanism as applied to a milling machine of the kind shown in Fig. 2, a motor on the saddle 22 drives, through a differential gear, a pinion engaging a rack fixed to the slide 24 and the planet carrier is connected through oneway clutches to two pinions, each of which engages a fixed rack but one acts through a reversing idler. Vertical movement of the saddle will then cause the pinions to roll on the racks and actuate the planet carrier so as to reduce the speed of traverse of slide 24 when the saddle moves either upwardly or downwardly. Traverse of the slide 24 by the motor is assisted by a weight and cable. As applied to a hydraulically operated lathe the saddle 63, Fig. 4, is attached to a piston 71 slidable within the hollow plunger 70 of a hydraulic cylinder 67, but normally maintained in a mid-position by springs 72, 73. Fluid is supplied by a pump 68 and a reversing valve 69 to displace the plunger 70 at a  uniform rate. If the pattern surface 79 is parallel to the work axis the piston 71 moves rigidly with the plunger 70 and the saddle will be traversed at a uniform speed but if the pattern moves the cutter slide 78 outwardly a piston 77 attached to the slide will displace fluid from the end 74 of its cylinder on the saddle, through the piston rod 71<SP>1</SP>, to move piston 71 within plunger 70, compressing spring 73 and thus causing piston 71 to impart a reduced rate of traverse to the saddle. Conversely, inward movement of slide 78 will increase the rate of traverse of the saddle and a perpendicular surface on the pattern will reduce the traverse to zero to allow the cutter slide to move radially outwards from the work. The tracer 80 is adjustable on the saddle by a hand wheel 83 and  controls the supply or fluid to a hydraulic cylinder 84 which moves the tool side 78 transversely on the saddle. A change over valve may be used to feed the slide 78 radially inwards instead of outwards when the traverse is stopped. In a modified form of hydraulic control the slide 108, Fig. 8, carrying the work 110 is traversed by the rod 117<SP>1</SP> of a piston 117 in a cylinder 116 attached to the saddle 107 and fed by a pump 114 and reversing valve 115. A cylinder 118 is attached to the bed 106 and contains a piston 119 connected to the saddle so that during a traverse of the slide 108 to the left, upward or downward movement of the saddle caused by the tracer 111 controlling fluid supply to a cylinder 113, will draw fluid through one of the non-return valves 121, 122 and pipe 122<SP>1</SP> from the right hand end of cylinder 116 to reduce the pressure therein and slow down or stop the traverse, fluid from the other side of piston 119 proceeding by one of the non-return valves 123, 124 to an exhaust line 125. In all the mechanical trains, devices for taking up backlash are used, and the invention may be applied to grinding or flamecutting copying machines.