Patent GB-1157211-A (GB)
Title: Improvements in or relating to Machines suitable for use in operating along marginal portions of Workpieces
IPC: B23Q15/22
Filed: 1966-07-28
Abstract: 1,157,211. Skiving machines. BRITISH UNITED SHOE MACHINERY CO. Ltd. 28 July, 1966 [29 July, 1965], No. 33850/66. Heading B4B. [Also in Division H2] A machine similar to that disclosed in Specification 989,874 for skiving the marginal portions of workpieces comprises means for automatically bringing about a reduction in the speed of a D.C. motor 66 driving the workpiece feeding members 16, 18 while the corner detecting photo-electric cell 170 remains uncovered during the negotiating of a corner of the workpiece and for restoring the speed of the motor when the coll 170 is again covered by the workpiece. The machine is also suitable for operating on workpieces provided with a notch at the start and/or at the end of the workpiece margin. For this purpose, a second photo-electric cell 172 is uncovered, after the counting of a predetermined number of corners, by a notch at the end of the workpiece margin. Transfer of control from the cell 170 to the cell 172 is brought about by the passage of the penultimate corner of the predetermined number of corners of the workpiece past the cell 170. In the case of a workpiece having a notch at the start, which delays operation of the steering members 70, 72 until the periphery of the workpiece beyond the notch can engage the finger 78 sensing the edge of the workpiece, the workpiece is guided by an edge gauge (130), Fig. 7 (not shown), which is movable between an operative position, in which it locates a workpiece being fed to the knife (20), and an inoperative position. A spring- influenced pivotally-mounted extension edge gauge (134), similarly movable between operative and inoperative positions, is also provided. When a workpiece is between the feed and steering members, normally-closed switches 46, 96 respectively are opened. The sensing finger 78 is carried by the core (122), Fig 3 (not shown), of a differential transformer (76) controlling a servomotor 74 driving the steering members 70, 72, the transformer core being locked by an arm (120) of a slidable bar (118) connected to the spring-influenced armature (124) of a solenoid (126), when the latter is de-energized. The member 72 is attached to a shaft 80 journalled in a bracket 82 which is rocked to raise the member 72 when a solenoid 102 is energized. Waste is removed from adjacent the knife by a nozzle (160), Fig. 2 (not shown), connected to a vacuum system. The knife (20) is laterally adjustable by a hand wheel (154). The machine is controlled by electrical circuits Figs. 12a, 12b and 12c (not shown), which are respectively, an optical work sensing and control circuit, a speed control circuit by the motor 66, and switching and counting circuits. The circuit Fig. 12a includes the two photo-electric cells (170, 172) a selector switch (190) and two transistors (194, 196). The circuit Fig. 12b comprises a uni-junction transistor (228) and a double-bridge circuit (210) including silicon rectifiers (220, 222). The circuit Fig. 12c includes the normally-closed switches (46, 96), the solenoids (102, 126), the servomotor (74) and differential transformer (76) and selector switches (290, 320 and 351) and comprises a counting and sequencing circuit controlled by the photoelectric cells (170, 172), Fig. 12a (not shown) and including silicon rectifiers (300, 302, 304, 306 and 308).