Patent GB-151081-A (GB)
Title: New or improved machine for grinding the edges of lenses and the like
IPC: B24B9/14
Filed: 1919-06-13
Abstract: 151,081. Course, J. June 13, 1919. Lenses, grinding; bevelling. - A machine for grinding and bevelling the edges of lenses &c. comprises a holder for the lens mounted on a rotary shaft carried by a frame adapted to swing to bring the edge of the lens into contact successively with two grinding - w h e e l s whereby both bevels are ground, t h e frame, when the lens is in contact with a grinding-wheel, being oscillated under the control of a former having an outline corresponding to that of the lens and mounted on the lensholding shaft. A framework 1 has journaled therein two grinding-wheels 2 and between the wheels is provided a swinging frame 7, rotatably mounted upon the end 10 of a hollow cylindrical shank 8 slidably but non-rotatably supported in a bearing 9, and adapted to be swung to present the lens to either wheel at the correct angle. The frame is swung over by means of a handle 11 secured to a spindle 12 rotatably mounted in a cover 14 secured to the shank and having a cranked end 13 engaging between a pair of flat springs 16; movement of the handle is limited by steps 22, which are adapted to engage a finger 21 on the handle 11, the lens thus being held up resiliently to the grinding-wheel by the springs 16. Mounted in bearings 24, 25 in the frame is a shaft 26 free to slide ondways and having at its lower end a clamp 35 adapted to co-operate with a rotatable foot 37 bearing on a ball 39 to hold the lens 40. At the upper end the shaft has therein a transverse pin 27 engaging in slots in the hullow lower end of a spindle 31 rotatably mounted in a nut 30 screwing into the frame and engaging a ball thrust bearing 34 bearing on the pin whereby movement of the nut lowers or raises the shalt 26; a spring 28 is located beneath the pin 27 in a hollow sleeve 29. The spindle 31 carries a cam or former 32 of the shape to which the lens is to be ground adapted to engage tappets 52 adjustably carried by arms 51 formed on the shank 8, one tappet engaging the cam when the frame is swung over to one grinding-wheel, and the other tappet engaging the cam when Hie frame is swung over to the other grinding-wheel. The shaft 26 is rotated through toothed gears 41, 42 by a shaft 43 located inside the shank and having a keyway engaged by a part 45<a> of a sleeve 45 surrounding the shaft and driven through worm-gearing by one of the. grinding-wheel shafts. To prevent scoring of the grinding-wheels the shank 8 is moved endways, to carry the lens across the face of the grinding-wheels, by means of a cam surface 59 formed on a gear-wheel 60 and engaging the end of the shank; the shank is held up to the cam by a spring 67, and the wheel 60 is driven by a pinion 66 on the sleeve 45. To insert or remove a lens, the frame 7 and shank 8 are withdrawn longitudinally through the bearing 9, such movement also moving the shaft 43 axially of the sleeve 45 whereby the shaft is unclutched from the driving-shaft 76 and ceases to rotate. The clutch comprises a conical part 75 on the driving- shaft 76 provided with a recess 74 adapted to accommodate a ball 73 having driving engagement with a slot in the pinion 66. Withdrawal of the shaft 43 from beneath the end 69 of a lever 70 allows this to fall into a slot 71 in the sleeve 45, and the end 72 of the lever rising, the ball is freed from the recess 74. On returning the frame and the shank to the operative position, the clutch is thrown again into gear. The movement of the frame 7 to and from the grinding-wheels may be performed automatically by crank gearing driven from the wheel 60 and thrown in and out of operation by a clutch operated by a trip gear by the wheel 60. In grinding the lens this is preferably swung over into contact with both grinding-wheels successively so that the grinding of both bevels proceeds by short stages until the lens is down to size. In setting the lens in the holder, the optical centre of the lens is positioned in correct register with the cam 32 by securing adhesive disks 36 to the lens having central pin-holes brought into register with the optical centre, the disks being then set concentric with the circular clamps 35, 37. According to the Provisional Specification, the lens may be fed up to the grinding-wheels by cam-gearing operating on the tappets, the feed automatically ceasing when grinding is completed, and to equalize the wear of the grinding-wheels, these may be moved laterally instead of moving the lens; for grinding meniscus lenses the tappetheads may be removable and adjustable and of a shape to give the necessary undercut.