Patent GB-954443-A (GB)
Title: Improvements in or relating to apparatus for the grinding of spherical or cylindrical bodies
IPC: B24B11/06
Filed: 1961-10-07
Abstract: 954,443. Grinding facets on spherical or cylindrical objects. R. W. KOHN. Oct. 3, 1962 [Oct. 7, 1961], No. 36127/61. Heading B3D. An apparatus for grinding facets on spherical or cylindrical bodies such as glass beads x comprises a carrier plate 10, Fig. 1, apertured to receive the beads, a lower support plate 12 having a friction surface 18 on which the beads are supported, a superposed and vertically-movable grinding device 21, means for causing relative movement between the carrier plate and the support plate to rotate the work between grinding operations, and means for bringing the grinding device, carrier plate and support plate into operative relation so that the beads may be ground. When the grinding wheel 21 is moved downwards by a lever 23 into grinding contact with the beads, the latter are pressed into the rubber or like surface 18 of the support plate 12 and are thereby prevented from rotation whilst grinding. When the wheel 21 is raised, the support plate is manually rotated to bring the objects to new positions prior to the next facetgrinding contact. Water is supplied during grinding by a central channel 24. In the embodiment of Figs. 2 and 3, the intermittent grinding and work re-positioning actions are effected automatically and by powered means. The belt-driven wheel 70 is mounted in a head 72 which is raised and lowered in timed relation with the movement of the carrier plate 30 by a cam 76 driven by a shaft 47 which is itself gear-driven from a speed-reducer 43 through a manually-operable variable-speed pulley 39 from a motor 37. Face-cams 54, 55 at the opposite end of the shaft 47 operate a rocking lever 56 which, through a step-by-step mechanism 61 or pawl and ratchet, causes intermittent uni-directional rotation and oscillatory motion of a disc 60 secured to the vertical shaft 31 on which the carrier plate 30, Fig. 3, is mounted, the shaft 31 being journalled in a pivoted member 78. In this arrangement, the carrier plate 30 is caused to move relatively to the fixed rubber-surfaced support plate 32 for the purpose of repositioning the beads. The beads are fed to the carrier from a hopper 100 and leave by a shoot 102 as they pass over a cut-out portion of the support plate 32. The oscillatory motion of the carrier plate may be varied by a lever, not shown, to provide the desired number and size of facets. In the embodiment of Fig. 1, a simple stop and/or timing means may be provided to aid the operator in the uniform lapping of the beads, but in the powered automatic machine, braking means 92, Fig. 3, is operated by a cam 95 in timed relationship with the movement of the carrier plate 30 to hold it during grinding, the support plate in this embodiment being fixed within a tray 34 which collects and drains the water or other liquid supplied through the grinding wheel spindle 71. The grinding head may be swung clear of the tray 34, after it has been raised by a pedal 81b, to permit the fitting of a carrier plate of different dimensions. When the beads are of cylindrical shape, the apertures in the carrier plate are rectangular so that the beads are constrained to rotate only about their main axes.