GB1304915A - - Google Patents

Abstract

1304915 Casting composite articles; grinding and polishing lenses J & S WYLDE Ltd 28 April 1971 [29 April 1970] 20604/70 Headings B3D and B3F Apparatus for casting a holding block on to a multifocal lens preparatory to grinding, polishing and finishing the lens, comprises an annular lens-seating member 18, and means for receiving a lens button or support 38, the annular member 18 being rotatable about its axis over a graduated segment scale 44 and the means for receiving the lens support being rotatable over a second scale 46. In operation a lens button 38 is located in the mould so that pins 36 on a shaft 22 are received within holes 40. A lens blank is then seated on the ring 18 which is rotated for the amount of segment inset required as measured by the scale 44. The shaft 22 is then rotated over the scale 46 by an amount which corresponds to the axis of astigmatism prescribed, the shaft 22 being provided with a pointer 52. The lens button 38 and lens blank are now in their correct relative positions and a low melting alloy is introduced into the space between the button 38 and lens blank so as to anchor the latter to former. The lens blank and holding block are removed from the mould by pushing a rod 56 against the action of a spring 58 so that the nose 60 of the rod presses against the underside of the lens button 38 and ejects it.