Grinding device for the simultaneous grinding of the two surfaces of a continuous glass ribbon can be advanced in the horizontal plane

摘要

671,961. Grinding sheet glass. PILKING- TON BROS., Ltd. Aug. 24, 1950 [Ang. 24, 1949], No. 22055/49. Class 60. A method of grinding horizontally-disposed flat glass on both faces simultaneously is characterized in that the underface is ground by a rotary disc having an annular series of curved bars, the circumferential width of each bar and the angle which its leading edge makes to a radius at any point increasing continuously from the inner to the outer end of the bar so that abrasive fluid supplied to the centre of the annulus is driven between the bars where, it is subjected to a lifting force which distributes it along the entire length of the upper surfaces of the bars. This lifting force is produced by the configuration of the bars 12, 13 the leading faces of which are inclined to the upper surfaces at an obtuse angle which diminishes continuously from the inner to the outer end of the bar. The abrasive fluid is fed upwardly through a shaft 22 into the centre 17 of the annulus where it is driven outwards into the channels 15 under the combined effect of the hydrostatic head and centrifugal force. The disc is preferably constructed with.a rim 14 having a surface of relatively soft material and is made to a diameter slightly in excess of the width of the ribbon of glass so that connecting channels 16 are progressively uncovered as the disc rotates to allow abrasive fluid to move along the channels 15. If the disc is constructed without a rim, soft metal plugs may be inserted in the channels 15 to regulate the flow. The discs are arranged in co-axial pairs along the length of the glass and use progressively finer abrasive as the polishing stage is approached. In the smooth grinding discs the bars are of the same width as the channels while in the coarse grinding discs they may be twice as wide. The increase in the width of the bars may be from 5 to 10 cms. in proportion to the radius and the increase in the angle of the leading edge from 55 to 70 degrees. On the lower discs the leading face angle varies from 110 to 130 degrees at the centre of the annulus to 93 to 113 degrees at its outer diameter. The upper discs may have a perpendicular leading face since the distribution of abrasive is assisted by gravity. Rollers on opposite sides of the glass feed it between the discs which rotate at about 60 r.p.m.