GB580110A - Improvements in and relating to the grinding and polishing of lenses - Google Patents

Abstract

580,110. Lens grinding apparatus. LIEBOWITZ, B. March 29, 1944, No. 5805. [Class 60] Lenses are ground and polished on opposite faces simultaneously by the use respectively of a rotating tool treating one face and an oscillating or orbitally moving tool, the path of which may vary periodically, acting on the other face ; the lens is supported by the tools only, no holder being used. The apparatus is described as for use in a bench type drill, having a base 61 and a post 62 carrying an adjustable member 63, and comprises a lower lap 12 and an upper lap 13 between which the lens 11 is located. The lap 13 is removably mounted on a rod 14b slidable in a member 14, itself slidable in a sleeve 16 in which it may be keyed to prevent rotation. The rod 14b is pressed by a spring 14c and its axial movement is limited by a screw 14d movable in a slot 14e ; the sleeve 16 has at its lower end an enlarged portion 16b receiving transverse pivot pins 17 held by the arms of a fork 18 bored for rotational mounting on a stub shaft 20 secured in a bracket 22 adjustable on the shaft portion 63a of the member 63 ; the upper end of the member 14 has therein a socket to receive the ball of a ball-pin 23, which is held in a swinging arm 24 by a pin. The pin 23 is moved in an orbital path the radius of which varies periodically between a maximum and a minimum, thus giving the lap 13 a varying conical motion, by gearing comprising a pinion 32 held from rotation by an arm 43 and rotatable on a shaft 31 secured to a disc 30, which, in turn, is secured to a disc 29 ; the shaft and discs are rotated by the drill chuck 64, and through a planetary gear 33 engaging the pinion 32 and adjustable members 38, 41, 42 carried by the discs this rotation produces the orbital movement, described above, of the pin 23. The lower lap 12 is mounted removably on a cap member 51, screwed on a bearing 52, which is rotatable on a stationary hollow spindle 54 secured to a flange 55 carried by the base 61, and the height of the lap is adjustable by a screwed rod 57 having a head 57a rotatable in and axially movable with the cap 51, the screw engaging in the spindle 54 and being rotatable by a hand wheel 58 ; the screw is locked by an arm 59 and the bearing 52 has a part 52a serving as a pulley. The construction described above is intended for the treatment of lenses other than double-convex lenses with faces of equal curvature ; for those lenses, the pivoted sleeve 16 is not used, the member 14 being mounted in the outer end of an arm pivoted on a vertical axis to another arm, which, in turn is pivoted on a vertical axis to the bracket 22, the lap 12 thus moving parallel to itself when the shaft 31 is rotated by the chuck 64. This last described arrangement may be used also for lenses with nearly equal radii of curvature. Grinding or polishing medium is supplied by means of a cup 81 carried by the lower lap 12, the medium covering the lens. Lenses may be mounted in groups on a lenticular shaped block and ground simultaneously.