Patent GB-963819-A (GB)
Title: Automatic lens grinding machine
IPC: B24B13/04
Filed: 1961-05-19
Abstract: 963,819. Grinding lenses. COBURN MANUFACTURING CORPORATION. May 19, 1961 [Dec. 16, 1960], No. 18281/61. Heading B3D. Lens grinding apparatus for shaping compound surfaces on a lens comprises a first assembly for supporting a lens blank having one surface of known curve, a second assembly for supporting an abrading tool which travels on an arcuate path past the first assembly, and means for effecting relative movement of the components of the first assembly and of the second assembly to positions determined by said curve and by the desired centre thickness of the finished lens. A tool-supporting assembly 14 and a lenssupporting assembly 16 are supported by a housing 18 containing driving motors &c. and having attached thereto a housing 20 with a control panel 21. The assembly 14 includes a cup-shaped abrading tool 22 and means for rotating the tool at speeds desired by the operator and for causing it to travel on a selected base curve as by means of a track 26. The angular disposition of the tool with respect to its travel can be varied. The assembly 14 is longitudinally adjustable by means 28. A top deck 34 is adjustable about a pin 32 secured to a framing member 33 of the assembly, the axis of the pin passing through the centre of the semi-circular edge 38 of the tool 22. An oil bath housing 24 serves for lubrication of the surface being ground The assembly 16 includes a chuck 48 carried by a tailstock 46 adjustable, by a micrometer dial and hand wheel 50, on a carriage 44 movable, by a hand wheel 60, on a platform 40 secured to the housing 18. A yoke 52 is slidably mounted in the carriage 44, having slots 53, 53<SP>1</SP> engaged by rollers 55, 55<SP>1</SP>. The yoke 52 has at one end a notch 521 for co-operation with the pin 32. The other end of the yoke 52 is connected by a link 57<SP>1</SP> to a member 67 secured to a rod 61 rotatable, by a hand lever 58, in a block 59. The member 67 has a face 69 co-operating with a stop 71. The block 59 is adjustable, by a micrometer dial and hand wheel 56, on the carriage 44. The chuck 48 has circumferential clamping fingers 49 which engage a pitch block 95 secured to the convex surface 92 of the lens blank 91, the outboard vertical faces of the fingers 49 lying in a plane 53. A fibre ring 74 is interposed between the blank and the chuck. The ring comprises a cylindrical body 87 having arcuate projections 88, 90 extending longitudinally from the outboard face and a flange 76 extending inwardly from the inboard face. The inner periphery of the flange closely engages the periphery of the pitch block 95 passed therethrough. The ends of the projections 88, 90 are spaced 90 degrees apart and provide four-point contact with the convex surface 92 of the blank. In the case of a toric lens the four points of contact are 45 degrees from the major and minor curves. In operation, the assembly 14 is adjusted longitudinally and locked. The lens is mounted to the chuck, and the mean diopter value is set on the micrometer 56. The handle 58 is turned to extend yoke 52 to its outward position. Hand wheel 60 is thus operated to move the carriage 44 towards the assembly 14 until the yoke 52 engages the pin 32. The required centre thickness of lens is set by the micrometer 50.