Patent GB-214672-A (GB)
Title: Improvements in pantograph engraving machines
IPC: B44B3/00
Filed: 1922-10-31
Abstract: 214,672. Hope, W. H. Oct. 31, 1922. Engraving.-An engraving-machine of the kind wherein the tracing stylus is moved over a flat design plate to control electrically the operation of an engraving-tool for reproducing the design on a printing-roller, comprises a stylus carriage reciprocated transversely along a second carriage having lateral movement, electrical devices on the latter adapted to be coupled alternately to oppositely moving parts for effecting the reciprocation of the stylus carriage, a switch for controlling the electrical devices, switch throwing means consisting of an endless cable carrying adjustable stops actuated by the reciprocation of the stylus carriage, means for imparting to the printing-roller supports a movement corresponding to the lateral movement of the second carriage but of variable ratio thereto, means for imparting to the engraving-tool a reciprocatory movement corresponding to the movement of the stylus carriage but of variable ratio thereto, and an electromagnet, for controlling the operation of the engraving-tool, actuated by an electrical circuit which is closed by contact of the stylus with conducting portions of the design plate. The pattern 9 is supported on a bed 10 and the stylus 8 is mounted on a carriage 6 movable transversely on a carriage 5 which is movable laterally along rails 3. The top of the carriage 6 has a groove 11 in which are seated wheels 12 carried by brackets 13 on a carriage 14 movable transversely on tracks 16. Electromagnets 23, 24 are secured to the carriage 14 in different planes and are energized alternately to couple the carriage 14 alternately to the upper and lower runs respectively of a belt 17 driven continuously by a motor 21. The circuit of the magnets 23, 24 includes a battery 86 and a snap switch 25, Fig. 9, comprising a pivoted arm 26 influenced by a spring 27 adapted to throw the arm quickly to either side of its dead centre position when the arm is pulled either way, by an endless cable 28. The latter passes round idle pulleys 29 and its lower run passes through a guide tube 30 on the carriage 14, the ends of the tube 30 coacting with adjustably fixed stops 31 on the cable to throw over the pivoted arm 26 of the switch at the end of each transverse movement of the carriage 14. By this means, the carriage 14 is reciprocated transversely of the machine, and with it the carriage 6 which carries the stylus 8. A cable 35 has its ends wound round and secured to a drum 32 journaled on the carriage 6 and passes round pulleys 36, 37, on the carriage 5, the shaft of the pulley 36 carrying a pinion 38 gearing with a rack 39 fixed to the machine base. As the stylus carriage 6 reciprocates transversely the carriage 5 is reciprocated laterally, so that the stylus trends diagonally across the pattern. The drum 32 is held against retrograde movement by a dog 34, Fig. 4, and is engaged by a friction pawl 43 carried by an arm 42 having a pivoted pawl 41 engaging a rack 40 'on the carriage 5. At each reversal of motion of the carriage 6, the pawl 41 swings about its pivot, thereby raising the arm 42 and causing partial rotation of the drum 32 which exerts a pull on the cable 35 to turn the pinion 38 and advance the carriage 5 one step laterally so that the stylus 8 on the carriage 6 travels on a new diagonal line over the pattern. One or more sets of diamond cutters 62 are carried by racks 50, 52, Fig. 1, actuated from a pinion 49 on the shaft of a radially slotted wheel 48 mounted on a fixed upright 46 and driven by a cable 61, Fig. 2. This cable passes round a number of radially adjustable knobs 56 on the wheels 48 and has its ends secured respectively to a screw 59 and a reel 60 mounted on uprights 57, 58 at opposite ends of the carriage 14. By varying the, position of the knobs 56, the ratio of the travel of the cutters 62 to that of the stylus carriage 6 may be varied. The printing-roller 63 to be engraved is rotated synchronously with the movement of the carriage 5 and in variable ratio in a similar manner by means of a cable 75, Fig. 6, having its ends secured to uprights 77, 79 on the side of the carriage 5 and looped round a series of adjustable knobs 74 on a fan-shaped counterbalanced plate 72 carried on the shaft 71 of the members 69, 70 supporting the work 63. Each diamond cutter 62 is controlled by an electromagnet 64 adapted, when energized, to lift the cutter off the work, the pattern or background being prepared in non-conducting varnish on a metallic plate. For this purpose, the circuit of the magnets 64 includes a wire 65. from one terminal of a battery 66, and a wire 45 to the machine base 10 with which the pattern 9 is electrically connected, the other battery terminal connecting by a wire 67 and switch 68 with the stylus 8.