GB869040A - Improvements in and relating to the automatic control of the handling and working ofwork pieces on machine tools - Google Patents

Abstract

869,040. Control of several motors. COMPAGNIA ITALIANA FORME ACCIAIO. Nov. 11, 1958 [Nov. 11, 1957], No. 36275/58. Addition to 816,105. Class 38 (3). [Also in Groups XXII, XXXVIII and XL (b)] In a method of controlling the operation of a machine tool such as a drill or a punch on a workpiece such as a metal plate at a number of points defined by a system of co-ordinates, a separate tape and a co-operating scanning head are used for each of two co-ordinate axes, each tape being made of flexible, opaque, inextensible material, and being provided with pin holes at positions corresponding to the points on the workpiece at which operations are to be effected. The relative movement between each tape and its related scanning head corresponds to the relative movement between the workpiece and the tool in the direction of the respective co-ordinate axis. Each scanning head comprises a light source on one side of the tape and, on the other side of the tape, one or more pairs of photo-electric cells which may be excited when light rays from the source pass through pin holes in the tape, one cell of each pair operating, when thus excited, to produce a considerable deceleration of the relative movement associated with the head, and the other cell operating quickly to stop such movement. As shown, Fig. 1, an elongated workpiece 6, in which holes are to be punched at predetermined positions, is mounted on a table 23 which is movable longitudinally on rollers 24 through rack and pinion gearing driven by an assembly comprising an electric motor 31, a smaller motor 26, speed reducers 27, 29, electromagnetic clutches 28, 30, and an electromagnetic brake 25. High-speed movement of the table 23 is effected by energizing motor 31 and clutch 30; slow speed is obtained by energizing motor 26, clutch 28, and brake 25; and rapid braking is achieved by de-energizing motor 26 and brake 25 while clutch 28 remains closed. The longitudinal movement of the workpiece 6 is controlled by a tape 48 stretched parallel to and mounted for movement with the workpiece, and a scanning head 52. A second tape 51, and a scanning head 54, control the transverse movement of a carriage 8 on which a punch 4 is mounted, fast and slow movement of the carriage and rapid braking thereof being transmitted through a worm drive 12 from an assembly comprising high- and low-power motors 13, 13a, clutches 14, 14a and a brake 16. Photo-electric control apparatus.-Each scanning head 52, 54 comprises two scanning boxes 66, 67 (Fig. 3) each having a pair of diaphragms 68, 69 and 72, 73, between which the tape runs, and an opaque, insulating base 70, 74. Ten holes are drilled in the diaphragms and base of each box along lines 99, 100, a photo diode 86 (Fig. 5) being disposed in each hole in the bases and a light source 76 being located on the other side of each pair of diaphragms. Each tape 48, 51 (Fig. 9) has ten tape lines corresponding to ten gauge lines on the workpiece 6, and each hole to be punched is represented by a pin-hole in the corresponding position on the tape 48. Tape 51 has ten pin holes (five only shown) arranged diagonally, one on each tape line. Operation.-The workpiece 6 and tape 48 are set in longitudinal movement at high speed. When a pin hole in tape 48 reaches line 99 (Fig. 3) of scanning head 52, it permits light to impinge on a photo diode in box 66 to produce a signal which operates circuitry (not shown) to decelerate the workpiece. When the pin hole reaches line 100, the corresponding photo diode in box 67 is illuminated to apply swift braking to the workpiece to cause the corresponding photo diodes in scanning head 54 to be activated, and to initiate the transverse movement of the punch 4 and tape 51. When the pin hole in tape 51 which is located on the same tape line as the pin hole in tape 48 reaches line 99 of scanning head 54, an activated diode operates to decelerate the transverse movement of the punch, and when the pin hole reaches line 100, the punch is stopped, and operated by drive mechanism 3 (Fig. 1). When all the holes in the tape 51 have been scanned and holes punched where appropriate, the high-speed longitudinal movement of the workpiece is resumed.