Patent GB-615080-A (GB)
Title: A new or improved machine for making the friction wheels for pocket lighters and like articles
IPC: B23F1/04
Filed: 1946-08-23
Abstract: 615,080. Serrating articles by chisel cuts. TRETHEWEY, W. B. Aug. 23, 1946, No. 25214. [Classes 83 (ii) and 83 (iv)] A machine for forming continuous longitudinal indentations on the surface of a workpiece includes means for supporting and rotating the workpiece, a cutter blade, means for effecting continuous relative movement between the cutter blade and the workpiece in the lengthwise direction of the workpiece, and means for rapidly reciprocating the cutter blade transversely to the longitudinal axis of the workpiece. In the embodiment described, a carriage comprising an upper part 22 embracing tie-rods 13, 14 and a lower part 24 carrying a cutter blade 25 and associated operating gear, is reciprocated by a lead screw 16 operating in a split nut 23 which may be opened by a handle 26 to permit manual movement of the carriage, the portion 24 of the carriage being constrained to follow the movement of the upper portion 22 by the engagement of a lug 31 within a forked portion 30 of the portion 22. Projections 50 on a cam 44, rotated by a main drive shaft 15 which drives the lead screw 16 through gears 18, 19, 20, 21, successively engage within a slot 49 in a plunger 33 carrying the cutter blade 25 in a closely fitting plug 77, to retract the plunger 33 against the action of a spring 43 and then release it to allow the spring to drive the cutter blade 25 against the workpiece 35, which is supported and rotated by a chuck 37, driven from the lead screw 16, and a steady 38. Variation of the level of presentation of the cutter blade 25 to the workpiece 35 is effected by rotation of the screw 36, which causes rotation of the lower portion 24 of the carriage carrying the plunger 33 about the tie-rod 14, corresponding adjustment of the anvil 34, which is offset from the cutter blade 25, being effected by its rotation in its eccentric mounting 61. Variation of the presentation angle of the cutter blade is effected by rotation of a strip 52 about a screw 53, the end of the strip bearing against a flat strip 51 on the plunger 33, which may be held in a retracted position clear of the cam 44 by a catch 57 engaging in a slot 56. Opposite the anvil 61 is a steady 62 carried on a spring- urged rod 63, which may be retracted by a handle 65 and held by the engagement of a pawl 69 in a toothed quadrant 70. Provision for workpieces of varying diameter, requiring a varying number of cuts per revolution of the work, is made by varying the gear ratio between the drive shaft 15 and the lead screw 16. The gear ratio between the lead screw 16 and the chuck 37 is chosen to ensure that the indentations of successive turns of the helix (Fig. 7) do not overlap and do not have spaces between them. In a modification, Fig. 9, provision is made for momentarily interrupting the rotation of the chuck 37 and the reciprocation of the carriage at the times when the cutter blade 25 strikes the workpiece 35, by the insertion of a Geneva wheel 119 in the drive to the lead screw 16, pins 117 on the main drive shaft pulley 17 engaging in slots 118 in the wheel 119 such that as one pin 117 leaves a slot 118, another pin 117 is entering a slot 118, the wheel at these times being momentarily stationary. The invention is applied. to the manufacture of friction wheels for pocket lighters, steels for sharpening purposes, milling-cutters and rotary files. When used for friction wheels the workpiece is preferably tubular and is afterwards parted to form the individual wheels, as by ganged circular saws. The individual wheels are then broached to remove burr, casehardened and finally ground to size.