Patent GB-222716-A (GB)
Title: Improvements in automatic engraving machines
IPC: B23Q35/20
Filed: 1923-12-06
Abstract: 222,716. Braren, L. K. Dec. 6, 1923. Engraving.-The design to be engraved is resolved into component movements at right-angles, and these movements are transferred to cams which are utilized to control the cutting tool through the intermediary of a pantograph linkage. An additional cam may also be provided for controlling the movement of the cutter in the third dimension. Workholders adapted for work of various shapes and means for automatically or manually stopping the machine are also described. The cutting tool may also be controlled manually from a tracer. General arrangement. A frame 1, Figs. 3 and 4, is provided with a guide 2 on which are mounted (1) a bracket 3 carrying a pantograph linkage 101 - - 104, a cutting tool 5, and a tracer 6; (2) a slide carrying a work support 128; and (3) a second slide carrying either a casing 7 containing automatic controlling mechanism or a pattern table 130. The tracer 6 is fixed on the end of the link 104, and the tool 5 is mounted in a bracket 109 slidable on the link 102 which is adjustable on the links 103, 104. The linkage can oscillate in a horizontal plane on pivot screws 117, 118 carried in a bracket 119 mounted to allow for vertical movement on a horizontal pivot shaft 46. Pivoted to the bracket 119 is a slotted arm 132 sliding on a bolt 134, a screw 135 limiting the depth of cutting. The weight of the linkage is counterbalanced by counterweights 122, 123 adjustably fixed on rods 120, 121 extending from the links 101, 103. The tool 5 is rotated by a belt running over idle pulleys and driven by an electric motor spring-supported on a hinged bracket for maintaining the tension of the belt. Automatic controlling-mechanism. Mounted in the casing 7 is a shaft 8, Figs. 5 and 6, carrying cam discs 22, 23, 25, the first two representing the components of the design in a horizontal plane and the cam 25 the vertical component. The cams 22, 23 act through arms 33, 35 on spring-pressed levers 29, 30 pivoted respectively at 31 and 32 and situated mutually at rightangles, the tracer 6 extending through a sleeve 37 sliding in a slot in the lever 30 and carrying a bush 38 engaging a slot in the lever 29. The lower end of the tracer rests on a plate 40 which is suspended by parallel links 41 from the lever 30 and is spring-pressed upwardly so that the tracer is raised in accordance with the movements of a lever 43 co-operating with the cam 25. The cam shaft 8 is driven by change-gear wheels and worm gearing through a clutch 12. Manual control. The tracer 6 is moved over a pattern mounted on the table 130. In order to adjust the points of the tracer 6 and tool 5 into a plane containing the pivot axis 46 before executing plastic reproductions, a gauge 136, Fig. 3, is removably mounted on that axis. Work-holders. The work-holder may be rotated, reciprocated or oscillated. For engraving on cylindrical and conical objects, a holder 60, Fig. 10, is rotated by worm gearing 58, 59 from the shaft driving the cam shaft 8, the holder being angularly adjustable about the axis of the worm. For straight-line engravings, a cam 28, Fig. 14, mounted on the lower end of the camshaft 8, is adapted to oscillate a pivoted arm 64 which is slotted to receive a slide 66 connected by a telescopic rod 68 to a toothed sector 71 adapted to reciprocate by rack and pinion gearing a slide carrying a work-holder. For engraving on an arcuate surface, the sector 71 is arranged to oscillate the work-holder. The work-holder may be advanced continuously or intermittently. Stopping the machine. The clutch 12 may be automatically disengaged to stop the cam shaft 8 after a part-revolution by means of a controlling lever provided with a spring-pressed nose engaging a cam 26, Fig. 5, on the shaft. The nose may be supported by a stiff spring such that pressure on the lever will disengage the clutch at any time, an eccentric being provided for holding the lever in the disengaged position.