Patent GB-146490-A (GB)
Title: Process and appliance for grinding safety razor blades
IPC: B24B3/48
Filed: 1920-07-05
Abstract: 146,490. Schr÷ther, W., (Assignees of Braun, H. A. and Schmidt, E.). March 22, 1919, [Convention date]. Void [Published under Sect. 91 of the Act]. Stropping-apparatus.-A machine for grinding safety-razor blades comprises a rotating shaft 4 carrying grinding-wheels 9 and a shaft 3, driven through variable-speed friction gear 5, 6 and worm gearing 7, 8 from the shaft 4, and carrying eccentrics 13, two cams 22, and a cam 23. The blades are mounted in holders 10 pivotally carried by a frame 11 and connected to bars 20, located within the frame, by means of wires 21; the frame 11 is pivoted to supports 12 and is oscillated by the eccentrics 13 to move the blades up to, across the surface of, and from the grinding- wheels. The bars 20 are moved endways to rock the blade-holders by means of a lever 18 pivoted at 17 to the frame and acted on at its lower end by a lever 19 carried by an oscillating disk 28<1> having therein a slot 27 engaged by one end of a lever 26. The other end of this lever is loosely connected to a forked lever 25 which engages with the cam 23, and is pivoted to a support 24, and the lever 26 is engaged between its ends by the forked part 27<1> on a slide 28. The slide is moved by the engagement of runners 31 thereon with grooves in the cams 22, the slide being moved in opposite directions at the end of each revolution of the cams through the action of the crossed parts of the grooves. The grinding is stopped after any required number of reversals of the blades by mechanism comprising a ratchet-wheel 33 adapted to be moved one tooth at each reciprocation of the frame 11 by means of levers 34. 36 and a pawl 35, the ratchet-wheel carrying a disk 39 with notches 40 therein adapted to be engaged by one end of a lever pivoted at 42, such engagement of the lever with a notch allowing the outer end of the lever to fall and thereby also allowing the friction disk 6, whose shaft 43 rests on the lever, to fall out of contact with the disk 5; the movement of the lever also completes the circuit of an electro-magnet 44 which then acts as a brake to the disk 6. In operation, the shafts 4, 3 being rotated by a motor 1, the eccentrics 13 move the frame 11 to bring the blades up to the grinding-wheels and the cams 22 move the slide 28, thus moving the lever 26 to one end of the slot 27. The cam 23, through levers 25, 26, 19, 18, causes the blades to rock into contact with one face of the grinders across which they are moved by the eccentrics 13. Continued rotation of the shaft 3 causes the blades to rock into contact with the faces of adjacent grinders whilst being moved outwardly by the eccentrics 13. The other grooves of the eccentrics 22 then come into operation and cause the lever 26 to move to the other end of slot 27 so that the next stroke of the lever 25 brings the blades into contact with the same face of the grinders as on the previous stroke, but with the blades moving, under the action of the eccentrics 13, inwardly across the grinding-faces. This sequence of operations is repeated until the lever engages one of the notches 40 when grinding is completed and the blades may be changed; the grinding of blades by this means is stated to prevent the formation of burrs on the blade edges. In a modification, the endlong movement of the bars 20 for tilting the blades is produced by means of two electro-magnets whose plungers operate the bars, and to which energizing-current is supplied to give the correct sequence of operations by means of a controlling- switch rotated by the shaft 3.