Patent GB-617220-A (GB)
Title: Apparatus for shaping objects provided with curved surfaces
IPC: C03B33/04
Filed: 1946-08-19
Abstract: 617,220. Lens cutting and bevelling. HOFFER, H. G. Aug. 19, 1946, No. 24652. [Class 56] [Also in Group XXII] Apparatus for cutting and bevelling non-circular lenses &c. includes a rotatable spindle for holding the lens blank and a fixed pattern cam, a rocker shaft parallel to the spindle with a cam follower and tool holder, and means for axially moving the rocker-shaft while under the influence of the pattern cam to impart a combined transverse and axial movement to a tool in the tool holder so that it follows the curved surface of the lens. As shown, a frame 16 mounted on a base 15 supports a compound spindle 18 with a pair of opposed friction jaws 19, 20 for holding the lens blank with its axis along the axis of the spindle. The shaft 22 secured to the jaw 19 is journalled at 23, 24 and has a slot and key engagement with the sleeve 28 of the pinion 29. When the wedge member 30 is rotated on the shaft the cam faces 32, 33 cause the wedge, the collar 25 and the shaft 22 to which it is secured to move endwise against the spring 27, permitting the blank to be positioned. The jaw 20 is secured to the shaft 36 journalled at 37, 38, adjustable endwise by the collar 39, and with a similar pinion 40, the pinions being driven at the same speed by gears 41, 42, and the pattern cam 43 is fixed at the end of the shaft. The rocker shaft 45, journalled at 46, 47, 48, has a cam follower arm 49 fixed thereto, with a resilient extension 52 and follower wheel 55 which is kept in contact with the cam 43 by the spring 65. The screw 56 adjusts the angle of the arm 49 and therefore the size of the lens to be cut. Bevel cutters 61, 62 are held in tool holders 57, 58, fixed to the rocker. A sleeve 68 with cap 69 is fixed to the end of the shaft 45, and a stub shaft 70 extends through the cap and slides in a recess 77 of the rocker, confining the spring 72, while the transverse pin 73 pulls against the cap but permits the shaft 45 to rotate relative to the stub shaft. The part 74 of the stub shaft slides longitudinally on a gib on the frame 16, and the adjustable arm 77 is connected by universal joints 80, 82 to the parts 74 and 58. The arm 88 secured to the stub shaft at 90, and eccentrically secured at 89 to the gear 87, with the gear 85 reciprocates the rocker member. 95, 96 and 97 form a time switch. The reciprocation of the rocker causes the tools to cut in turn, and the wheel 55 following the pattern causes the tool holders to follow the same pattern. As the wheel 55 and tools 61, 62 move from the axis, the end 81 of the arm 77 will move transversely and since the end 79 is relatively fixed will also move axially, giving this combined movement to the tools. If the length of the arm 77 is adjusted to equal the radius of curvature of the lens the tools will follow the curvature of the lens. In the form shown in Fig. 7 the arms 49, 57, 58 are attached to the sleeve 100 journalled at 46, 47, 48, and with a fixed flange 101 in which spiral gears 103, 104 are mounted on fixed shafts 105, 106. Shaft 107 rotatable within the sleeve 100 has a fixed spiral gear 108 meshing with the gears 103, 104, while a squared portion 109 slides in the sleeve 110 which prevents rotation. The arm 88 reciprocates the shaft 107 moving the gear 108 which moves the gears 103, 104 and the sleeve' 100. Transverse movement of the follower is transmitted to the tools 61, 62, and causes the sleeve 100 and jaws 103, 104 to rotate, but since the gear 108 is fixed, the gears 103, 104 slide endwise, adding this axial movement to the transverse movement of the tools. The gears 103, 104, 108 must be chosen according to the radius of curvature of the lens.