GB1046748A - Process and apparatus for the preparatory grinding of rough conical shapes on precious stones - Google Patents

Abstract

1,046,748. Shaping precious stones. J.R.M. MICHIELSEN. Sept. 16, 1964 [Sept. 18, 1963; Jan. 24, 1964; Aug. 12, 1964], No. 37828/64. Heading B5E. Apparatus for the preliminary forming of rough conical shapes on precious stones comprises a carrier 51 for a first stone 1 and adapted to be continuously rotated by means 55, 59, a carrier 61 for a second stone 3 and adapted to be reciprocated and rotated in a step-by-step motion, and means 12, 13 for providing a relative approach between the two stones so that they are moved into contact and thereby, by a mutual cutting action, produce the preliminary conical shape. The stone 1 is held in a chuck 51 mounted on the end of a shaft 7 rotatable in a housing 8, which is slidable in a base-plate 11; the housing is urged by springs 12, 13 against an adjustable stop 14. The second stone 3 is held in a chuck 61, carried by a shaft 15 which is rotatable in a housing 16, the housing being mounted on a slide 17 movable in a base 19 against the action of a spring. The shaft 7 is rotated via a belt-and-pulley arrangement 54, 55, 56 and bevel gears 57, 58 driven by a motor 59. The motor also rotates an adjustable eccentric 21 which is adapted to co-operate with a roller 64 secured to the slide 17. In operation, the motor is started so that shaft 7 is rotated and the slide is reciprocated; in addition the shaft 15 is, at every stroke of the slide, partially rotated by a pawl-and-ratchet device 70, 71. In order to bring both stones into contact, the stop screw 14 is adjusted either manually or automatically thereby allowing the housing 8 to move under the action of the spring 12, 13; the rubbing action of the two stones is continued until the conical shapes 5, 6, Fig. 11 (not shown), are produced. In a modification, Fig. 21 (not shown), the two shafts 7, 15 are continuously rotated by means of bevel gears 57, 58, 78 and pulley-drive 55, 56, 76, 77; the reciprocating movement of the slide 17 is produced by a piston-and-cylinder device 73 instead of the eccentric 21.- In other modifications, the axis of the shafts are arranged in various relative angular positions. In a further construction, Fig. 10 (not shown), a third shaft 28 is provided having a pin 31 which is adapted to press against the rear surface of the stone in order that a chamfer may be formed thereon by means of the stone 3.