GB1233472A - - Google Patents

Abstract

1,233,472. Grinding. CARBORUNDUM CO. 18 Feb., 1969 [29 Feb., 1968], No. 8620/69. Heading B3D. A sanding and polishing machine comprises a plurality of rolls 16, 18, 20 rotatably mounted on a grinding head 14 supported by a frame 12, an abrasive belt 22 carried by the rolls one 18 of which is adapted to apply pressure against a portion of the active run of the belt, and pressure means 40 spaced from said one of the rolls for applying pressure against another portion of the active run of the belt. The abrasive belt is guided over three rolls, the roll 18 being driven and comprising a contact roll for rough grinding a workpiece, such as veneered wood, fed beneath the belt by a conveyer 36. The roll 20 acts as an idler and is spaced from the control roll 18, the space therebetween accommodating the pressure means 40 consisting of a support plate 42 extending across the width of the belt 22. A pair of cover-plates are attached to the plate and extend therebelow to locate an air bag 56 which may have separate air cells. A flexible metal sheet 60 is located below the air bag and between the sheet and bag is a corrugated metal strip 66. A resilient pad 62 is adhered to the sheet 60 and a wearresistant canvas strip 70 is disposed below the pad and has its ends secured to clamps 72 adjustable by screws 80 to tension the strip. The plate 52 is vertically adjustable by differential screws 90. A second belt 106 is disposed to run transversely of the abrasive belt 22 over rolls 108, 110, 112 with its active run between the canvas strip 70 and the belt 22. Roll 108 is driven by a belt 120 fron a motor 114, roll 110 is mounted on a pivotally adjustable shaft to control tracking of the belt, and roll 112 is carried by a lever 148, at one end, mounted on a pivot 150 and, at the other end, guided by a roller 152 guided in a track 154, a fluid-pressure cylinder 158 acting on the lever to tension the belt. In operation, the plate may be vertically adjusted so that the lower run of the belt 106 is at the same vertical height as the lower part of the contact roll 18, the workpiece is rough sanded as it passes below the roll 18 and smooth sanded as it passes below the belt 106. By varying the heights of the plate 42, the workpiece may be either rough sanded or smooth sanded.