Patent GB-1431856-A (GB)
Title: Servo copying machine apparatus
IPC: B23Q5/36
Filed: 1973-06-20
Abstract: 1431856 Grinding TOYODA KOKI KK 20 June 1973 [27 June 1972] 29248/73 Heading B3D A servo-copying machining apparatus comprises a headstock 11 guided on a base 10, a main spindle 15 rotatable in the headstock and having means 20 for mounting a workpiece 19 and a template 22 having curved surface 21 corresponding to a not truly circular curved surface which is to be machined as the workpiece, a stylus 26 on the base adapted to contact the template, a first displacement detector 33 for producing an output according to the displacement of the stylus, a first servomotor 13 responsive to the output for effecting a copying movement of the headstock, a carriage 43 carrying a tool 45, a second servomotor 69 for effecting a correcting copying motion of the carriage, a second displacement detector 71 for detecting the correcting copying motion, and means 72 for generating a deviation output in response to the outputs from the first and second detectors, the deviation being applied to the second servomotor 69. As described, the apparatus has a tool in the form of a grinding wheel and the surface to be produced on the workpiece is trochoidal. The headstock 11 is movable along guide ways 12 on the base 10 by a lead screw 14 driven by the first servomotor 13 and has a motor 16 connection by worm-and-wheel mechanism 17 and pulley 18 to the spindle 15. One end of the spindle has a holder 20 for the workpiece 19 and the other end carries the template 22 formed with the surface 21. An arm 25 carries a truncated conical follower 26 for engaging the surface, the arm being mounted on a pivot 27 on a transfer table 28 and urged by a spring 31 so that the follower engages the template surface. The table 28 is intermittently adjustable by a motor 36 and screw 35 to axially adjust the follower 26 to compensate for reduction in size of the grinding wheel following dressing. The arm 26 co-operates with a movable finger 32 of the first differential transformer 33, the output of which is connected to an amplifier 34 and the first servomotor 13 and to the servo amplifier 72, the motor 13 effecting a copying movement of the headstock 11. The grinding wheel 45 is driven by a motor 44 on a carriage 43 movable along guideways 42 on a table 41 which, in turn, is movable along guideways 40 on the base by a feed unit 46, Fig. 3. The carriage 43 is engaged by a feed screw 48 at one end having a gear 49 meshing with a gear 51 rotatable by a handle 54 or by a rack-andpinion mechanism 53 driven by an in-feed cylinder 52 at a continuous rate determined by a throttle 58 for rough grinding and intermittently under the control of a valve 59 for finish grinding. The other end of the lead screw 48 is connected by thrust bearings 65 to a case 66 for a nut 68 engaged by a threaded shaft 67 connected by reduction gearing to the second servomotor 69, the drive from which causes axial movement of the case 66 and lead screw 48, the said one end of which engages the finger 20 of the second differential transformer 71 mounted on the infeed unit 50. The output from the transformer 71 is connected to the amplifier 72 which produces an output proportional to the difference in the outputs from the transformers 33, 71 to actuate the servomotor 69 so as to apply a correcting copying motion to the grinding wheel carriage and the axis l1 of the follower is maintained substantially aligned with the axis l2 of the grinding wheel. In another embodiment an intermediate base is driven by the in-feed unit 50.