Patent GB-190618170-A (GB)
Title: Improvements in Machines for Grinding and Polishing Lenses and other like Convex or Concave Surfaces.
Inventor: GRAHAM CHAUNCEY LE ROY
Filed: 1906-08-13
Granted: 1907-03-14
Abstract: 18,170. Graham, C. Le R., and Tilden, W. D. Aug. 13. Lenses.-In a machine for grinding and polishing lenses and other curved surfaces, particularly adapted for the production of toric lenses, a pair of radius bars are mounted in brackets independentlyadjustable on a support and capable of oscillating in vertical planes transverse to each other. A grinding or polishing head is carried at the end of one bar and engages with the work cemented to a work-carrying head carried at the end of the other bar. The bars have slightly differing periods of oscillation imparted to them in order to make the point of grinding contact change its position continually. The square-section radius bars 17, 18, Fig. 1, are slidably supported in sleeves 11, 12 carried by horizontal spindles 13, 14 capable of oscillating in brackets 3, 4, vertically adjustable in grooves 5 in the standard 2. The brackets 3, 4 are clamped in position by bolts 6, Fig. 3, having ends shaped to fit the grooves 5 and locked by nuts 7. The brackets are roughly placed in position and then rods 8 which pass through holes in these bolts are locked to the bolts by screws 9. These rods, which are screw-threaded at their upper ends and engaged by nuts 10 which bear on the top of the standard 2, serve to effect the final adjustment of the brackets. The radius bars are fixed in the sleeves 11, 12 by screws 16. A screw passing through a lug removably attached to the bar and engaging with the sleeve serves to give a final adjustment to the vertical position of the bar, and also to allow of a limited vertical movement being given to one bar with respect to the other during the grinding operation. To the ends of the bars are removably attached heads 21, 22. In grinding a convex lens as shown in Figs. 1 and 7, the upper head 22 carries the work while the lower head 21 carries the grinding or polishing device. The stem of the head 21 is held in a recess in the horizontal member 19 attached to the bar 17 by a sliding bar 23 operated by a handled cam 24. The stem of the upper head 22 is held in a recessed piece 26 by a screw 25. The screw 25 works through one arm of a forked end of an horizontal piece 20 attached to the bar 18, and the piece 26 is held to the other arm of the fork by a bolt 27. The piece 26 can be rotated about this bolt as a pivot to give an angular adjustment of the lens with respect to the grinder to allow one end to be ground away more than the other. The amount of this adjustment is registered by a scale 28. To facilitate adjustment of the lens about the vertical axis of the stem of the head, an horizontal segment scale 29 and pointer 30 are provided. In grinding a concave lens, the grinder is carried by the upper head and the lens on the lower one as shown in Fig. 11. The lens is attached by cement to a plate 31, which slides in dovetail grooves in cheeks 32 on the head 22. These cheeks are drawn together and the plate clamped in position by screws 33 engaging a transverse bar 34. A raised bearing ridge 35, Fig. 9, preferably of circular form against which the lens abuts to insure correct alinement. and an elliptical ridge 36 to assist in placing an elliptical lens in the correct position are provided on the plate 31. The heads 21, 22 are oscillated by eccentrics 45, 46 and connecting-rods 49, 50. Fixed guides 39, 40, engaging the pieces 19, 20, are provided on the frame to ensure the heads 21, 22 travelling in straight lines. The eccentrics are mounted on shafts 41, 42 at right-angles to one another and connected by bevel-wheels, one of which has a slightly less number of teeth than the other in order to give the shaft a differential degree of rotation and cause the point of grinding contact to shift its position constantly and pursue a path such as that illustrated'in Fig. 12. The arms of the eccentrics can be adjusted to regulate the amplitude of the oscillation of the heads to suit various widths and lengths of lenses. A conical receptacle 37 made of india-rubber &c., to allow of ready removal, having an annular collar 38 is provided to contain the grinding &c. materials and to supply it to the actiog surface as required.