Patent GB-1421332-A (GB)
Title: Apparatus for polishing gem stones
IPC: B24B9/16
Filed: 1972-03-23
Abstract: 1421332 Polishing gem stones SPECTRUM DIAMONDS (PTY) Ltd 20 March 1973 [23 March 1972] 13381/73 Divided out of 1421331 Heading B3D [Also in Division F2] Apparatus for polishing, shaping, grinding or cutting gem stones, such as natural or artificial rubies, emeralds, semi-precious stones, diamonds, hand glasses and the like comprises a polishing head 2, Fig. 1, for supporting a gem stone for polishing on a polishing surface, support means 3 for the head, lifting and lowering means for the support means, the polishing head being pivotally mounted on the support means for movement between an operative polishing position (as shown) and an inoperative store inspection and insertion position (Fig. 2, not shown), and complimentary abutment means 7, 9 on the support means and polishing head adapted to engage one another to determine the operative position. The support means con, sists of a. hollow shaft 3 which extends from a main housing 1 and the polishing head is pivot tally mounted on the rod for movement between an inverted position, for insertion and inspection of a gem stone, and an operativeposition determined by engagement of a member 7 on the head with a bracket 9 on the rod, fine adjustment ofthe operative position being effected by a micrometer screw 15. When the polishing surface is horizontal, the axis of the head may be adjusted to be perpendicular thereto by a gauge or spirit level placed on a surface 17, Fig. 3, of the head. The axis of the head is defined by a shaft 4 which is indexable by a motor and carries, for adjustment about a transverse axis by a micrometer screw 6, a shaft 5 which is also indexable by a motor to position a gem stone carried by a holder on the shaft 5 for polishing of facets on the stone. The polishing head is releasably retained in its operative position by a.spring clip 11 engaging the bracket 9. The support means in the form of the hollow rod 3, through which the leads for the motors for indexing the shafts 4, 5 pass, extends into the main housing 1 and is secured by a bracket 13, Fig. 6, to the upper end of a piston 10 of a dashpot 14 containing mercury. The dashpot is connected by a conduit 16 to a reservoir 18 having a floating piston 20 and adjusting rod 22, and the reservoir is connected by an adjustable restrictor valve 24 to an outlet pipe 26 and glass tube 28. Raising or lowering of the piston 20 by the rod 22 causes lowering or raising, respectively, of the piston 10, and hence the polishing head 2, and accommodates variation in thickness of the polishing plate. The adjustment also determines the polishing pressure which is inidicated by the height of mercury in the glass tube 28, Fig. 1. A bracket 30 is also mounted on the piston 10 and a threaded rod 32 passes through the bracket and engages an arm 34, Fig. 4, which is pivotally mounted and attached to the plunger of a solenoid which, when energized, acts on the arm to raise the rod 32 and hence the piston 10 to thereby lift the polishing head 2 from the polishing surface. Manual means 37 is also provided to act on the arm in the event of an emergency. When the polishing head is lowered, the valve 24 controls the flow of mercury to tube 26 so that the gem stone is gently lowered on to the polishing plate. The rod 3 and the piston 10 are oscillated about the axis of the piston, so that the polishing head oscillates on the polishing plate, by rotation of an eccentric 38 which is driven by a motor and engages the end of the rod which is urged by a spring 46 against the eccentric. The machine may be operated by programmed control means.