Patent GB-859650-A (GB)
Title: A grinding machine, particularly for grinding the rims of spectacle lenses
IPC: B24B9/14
Filed: 1959-02-05
Abstract: 859,650. Grinding. STRUNCK, H. J. Feb. 5, 1959 [Feb. 7, 1958], No. 4073/59. Class 60. A grinding machine, particularly for grinding the rims of spectacle lenses, comprises several grinding wheels working in parallel of which at least one is a diamond wheel and another a ceramic wheel, means for lowering the work on to any one of the grinding wheels and raising the work therefrom, and transferring means, preferably in the form of a spring-loaded scissors motion, automatically releasable by a control shaft, for transferring the work from one grinding wheel to the other by imparting a swivel motion to the workholder. A machine for grinding the edges of spectacle lenses has a diamond grinding wheel 6 and a ceramic grinding wheel 7. The lens is gripped between members 26, 34 mounted in a casing 4 which pivots about a horizontal shaft 5 so as to move the lens towards and away from a grinding wheel, the shaft 5 being carried by a part 2 which swivels about a vertical pin 3a so as to transfer the lens from one grinding wheel to the other. The member 26 is urged towards the member 34, so as to grip the lens, by a spring 31 and is retracted by operation of a lever 29. The member 26 is driven by a motor on the part 2 through belt 12, pulley 10, clutch disc 8, shaft 9, worm gearing 13, 14, shaft 25, worm gearing 18, 20 and shaft 19. The worm gearing 18, 20 can be disengaged by operating a pin 22. The member 34 is driven in synchronism with member 26 through gearing 38, 39 by a control shaft 37 driven through gearing 35, 36 by the shaft 19. A template 46 rotates with the member 34. With the lens in register with one grinding wheel, and the clutch 8, 10 disengaged by a spring 55 so that the lens is not rotating, grinding proceeds until the template 46 contacts an abutment 64 adjustably mounted in a frame 60 which is thus swung about pivots 58, 59 and against the urge of a spring 61 so that a thrust pin 81 also carried by the frame 60 engages the end 9a of the shaft 9, so engaging the clutch 8, 10 and causing partial rotation of the lens to a position in which the template 46 leaves contact with the abutment 64. The abutment 64 has formations 95 engaging formations 94 on a control bar 71, so that longitudinal movement of the bar 71 effects vertical adjustment of the abutment 64 and thus, through the template 46, of the lens. The means for swivelling the part 2 about the vertical pin 3a includes a lower member 130 movable about a pivot 132 between stops 134, 135 and clampable in desired position by a shoe 138 moved by a screw 139 to engage a friction block 137 on the member 130. An upper pivotal member 129 has a pin 141 co-operating with an abutment 140 on the member 130. A drum 153 secured to the member 130 contains a tension spring 154 secured at one end to a pin 156 on the drum and at the other end to a pin 155 on the member 129. The drum is embraced by a brake strap 157 secured at one end to a pin 145 on the member 129 and at the other end to a pin 159 on a lever 146 pivoted on the pin 145. If the member 129 is initially in a deflected position relative to member 130, operation of a Bowden cable 103 to move lever 146 against the action of a spring 147 causes slackening of the brake strap 157 so that the tension spring swings the upper member 129. The machine can be adjusted so as to work in any of the following ways (1) Grinding a lens in the V-groove of the ceramic wheel without preliminary grinding on the diamond wheel, (2) Grinding a lens on the diamond wheel followed by finishing in the V-groove of the ceramic wheel, (3) Grinding a lens on the diamond wheel followed by grinding on the cylindrical portion of the ceramic wheel.