GB613072A - Improvements in apparatus for polishing diamonds and the like - Google Patents

Abstract

613,072. Polishing diamonds. NAGY, A. April 18, 1946, No. 12018. [Class 60] Apparatus for polishing diamonds and the like of the type comprising a horizontal lap, means for rotating the lap, a table parallel to the lap, and a dop holder adapted to rest on the table and comprising an arm supported at one end on spaced feet and carrying at the other end a fixing head carrying a dop for supporting the diamond, the fixing head being rotatable in relation to the arm for the purpose of presenting the grain of the diamond at the correct orientation to the lap, and in which apparatus the fixing head is rotatable in relation to the arm about a vertical axis passing through the point of the diamond, comprises a stopbar on the table having a horizontal upper surface and a lateral extension on the arm carrying a downwardly depending point adapted to coact with and be supported by the stopbar to prevent further polishing of the diamond, said point'being at substantially the same distance from the line joining the supporting feet as is the diamond. Two diamond holders 11, co-operating with a lap 10, each comprise a metal bar having spaced feet 12 at one end resting on a horizontal metal table 13 and carrying at their other end, as in Specification 541,451, a fixing head 14 rotatably adjustable about a vertical axis 15 and carrying a diamond dop. Fixed to the table 13 are a pair of horizontal stop-bars 20; insulated from the table 13, which are adapted to be engaged by stop points 22, of metal, and 23, of insulating material, carried on lateral extensions 21 of the holders 11. The stop points are originally clear of the stopbars but when the diamond has been ground sufficiently they contact the bars to complete electric circuits which operate a lamp or buzzer; one stop-bar only may be used. The holders 11, and thus the diamonds, are reciprocated by rods 56 engaging the holders 11 and carried by a rod 47 reciprocated by a cam 50. The rods 56 are weighted by nuts 60 threaded on quick-pitch threads 59 on the rods so that on each complete reciprocation of the holders 11 the nuts 60 are rotated a quarter turn by engagement with spring-pressed pawls on the table 13, thus progressively increasing the load applied to the diamonds. The lap spindle 30 has conical ends engaging oiled cavities in top and bottom bearings (Fig. 3, not shown), the top bearing being mounted on cross slides for adjustment in any direction parallel to the surface of the lap. The lap 10 is kept heated to a temperature of 50‹-70‹ C. by an electric heater located beneath it. A drum 46 surrounds the lap to collect particles of diamond. Diamond dust may be fed on to the lap. According to the Provisional Specification, on completion of the electric circuits the diamond may be automatically lifted off the lap. Gauges may be provided for indicating progress of the work. The stops may be spring loaded or connected to a piston moving in an air cylinder in such a way as to increase the load on the diamond and then decrease it to zero. Specification 25,483/13, [Class 60], also is referred to.