GB182538A - Improvements in a machine for bevelling the edges of lenses and the like - Google Patents

Abstract

182,538. Standard Optical Co., and Long, C. M. March 31, 1921. Bevelling; lenses, grinding and polishing.-The lens or like article is rotated diagonallv across and against opposed bevelled grinding-faces of a rotary grinding-wheel, and is so mounted as to be movable axially and transversely of the axis, whereby toric, cylindrical, and irregularly-shaped lenses may be ground. The grinding-wheel comprises two discs 1 having opposing bevelled faces 5 and separated by a thin disc 6 of softer material, for example, felt. The discs are held on a shaft 2 by a sleeve 7 and a collar 7<1>, Fig. 9, the sleeve having passages 10<1> for water, which is carried by centrifugal force outwards and through the pores of the wheel to the bevelled faces; the water &c. is caught in a trough 11. The lens a is supported in a vertical plane diagonally of the grinding-wheel by clamping-heads 13. One head is carried by a spring- pressed spindle 14<1> mounted in a bearing 15<1> at the end of a carriage 16 comprising two arms 16<1> connected by a member 37, and the other head is carried by a shaft 14 and is connected to a sleeve 22 mounted in a bearing 15 coaxial with the bearing 15'. The spindle 14<1> may be moved axially, for insertion or removal of a lens, by a lever 33, which engages an annular recess in a collar on the spindle. The sleeve 22 is provided with a gear-wheel 24, and the outer end of the spindle 14 carries a lens-pattern 25. In order that the lens may rise and fall and move axially to keep the bevels in engagement with the grinding-wheel, the carriage 16 is pivoted, by horizontal pivots 17, to a frame 18 carried by fixed and adjustable vertical pivots 19 on a support 20. The support is vertically adjustable on guides 40, 40<1> in a bracket 21 on the main frame 4, whereby different sizes of lenses may be ground and wear of the grinding-wheel compensated for. The lensholder is driven through worm and spur gearing from a shaft 45. The spur-gearing comprises a wheel 57<1> connected to the worm-wheel 57 and journaled in the bracket 21 and driving a train of three wheels 60, the first two of which are carried by spindles 61, 62 in the frame 18 and the third by a spindle 59 in the carriage 16; the third wheel drives a wheel 63<1> carried by a spindle 63, which also carries a wheel driving the wheel 24. The pattern 25 contacts with a rest 26, and, in order to feed the lens gradually down on to the grinding-wheel, the rest is mounted on the end of a lever 64, Fig. 4, pivoted at 65 to the frame 18, the other end 66 of the lever engaging a cam 67. The cam is connected to a ratchet-wheel 69, and both are rotatably carried by a stud 68 on the frame 18, the ratchetwheel being fed one tooth at each revolution of the shaft 59 by a pawl 71 carried by an eccentric pin 70 on the shaft. The highest part of the cam initially contacts with the lever, and rotation of the cam gradually lowers the rest until the lowest part of the cam contacts with the lever; grinding is then completed, and the carriage is swung upwards to the position shown in dotted lines in Fig. 5. This action is brought about by a member 78, carried by the shaft 62, which engages a lever 77 pivoted on the bar 37 and moved into the path of the member 78 by a spring-pulled lever 74. The lever 74 moves to operate the lever 77 when a bolt 73 carried by the lever moves into a recess in the ratchet-wheel, this action taking place when the lowest part of the cam contacts with the lever 64; the upward movement of the carriage re-sets the cam 67 to its starting position and also releases the lever 77 from the pin 76. A new lens may then be substituted for the finished lens and the operations repeated.