Patent GB-565399-A (GB)
Title: Improvements in and relating to cutting, grinding or polishing machines for diamondsor other stones and the like
IPC: B24B9/16
Filed: 1942-05-19
Abstract: 565,399. Polishing &c. diamonds &c. JEARUM, F. C. May 19, 1942, No. 6794. [Class 60] In a machine for polishing &c. diamonds &c. in which the work is held in a dop and means are provided for moving the dop in an arcuate path in a plane normal to the plane of the rotating disc, means are provided for effecting a simultaneous radial displacement of the dop ; the means comprises an abutment co-operating with an adjustable former on the dop carrier. The disc 4, Fig. 1, is mounted with a radial adjustment in a crank disc 5 which is carried by a mandrel 6 in a block 7 and is rotated by worm gearing 6d. The disc is driven by a belt 10l, Fig. 2, passing round sheaves 10h on a counterpoised post 10a, thus enabling the drive to follow the planetary orbit of the disc. The block 7 is adjustable by means of a screw 7a in a slideway which is carried in a cross-bed 14. The cross-bed is carried by a rail on which it is pivotally adjustable for setting and is furnished with a rack 14c engaged by a pinion 14d on a shaft 14l mounted in bearings in the stand 1 and operable, at will, by a handle 14f to reciprocate the planetary axis B, B in a horizontal direction at right angles to its length. This reciprocation can be automatically effected by a connection with a variable throw crank mechanism 23b. A horizontal knife edge 15 is adjustably mounted on a block 15a on the stand 1 and engages a former 27; the knife edge may be carried by the bed 14 and reciprocated therewith to distribute the wearing contact of the knife edge, which may be straight or curved. The dop is carried on a radial arm 16a fitted with a vertical spindle 16 and having its outer end adjacent a calibrated rail 17 fitted with adjustable limiting stops 17a, 17b, Fig. 4. The arm 16a may be oscillated by means of wormteeth 18a on a sleeve 18 from which the drive is imparted to the spindle 16 through a friction clutch. The worm, serving as a pinion, is engaged by a rack or worm-wheel rotatable for initial adjustment on a link 20d which is reciprocated to oscillate the radial arm 16a from a second, variable-throw crank device 22g driven, with the disc 23b for reciprocating the bed 14, from a worm 21e. The radial arm 16a is provided with a radially displaceable carriage 25 pressed inwardly by springs 25b. A block 26 is detachably secured to the carriage 25 and is fitted with the roller 27 which co-operates with the knife edge 15 ; the roller is carried in a bracket 27b transversely adjustable in a slideway upon a head 27d which is rotatably mounted in the block 26 so that the axis of the roller 27 can be skewed to effect the radial movement of the block 26 as the radial arm 16a is oscillated. The upper side of the block 26 carries a spring-influenced slider 28 in which interchangeable dop holders are mounted and the adjustment of which is effected by micrometer. The grinding operation and initial adjustment may be observed through an eyepiece 33b to which light passes from a source in the base of the apparatus through the hollow spindle 16, or by means of an adjustable illuminated screen 33h carried by an arm 33j. Fig. 9 shows a dop holder mount comprising a cranked arm 31 for the dop pivoted at 31b on a horizontal axis about which it is adjusted by set-screws 32a in the head 32 ; the head can be canted about a pivot bolt 32b by set-screws 33a. The cross-slide 33 on which the head is mounted is carried by a vertical slider 34a mounted on the member 30 secured to the feed slide 28. In another form, shown in Fig. 14, the dop holder while being adjustable about the axis 34l, and along that axis, can be driven by bevel gearing 31h ; the rotation may be effected step-by-step by the provision of a ratchet. The holder may be adapted for polygonal dops. Specification 565,407 is referred to.