Patent GB-1066127-A (GB)
Title: Belt sanding and polishing machines
IPC: B24B21/00
Filed: 1965-08-02
Abstract: 1,066,127. Abrading. CARBORUNDUM CO. Aug. 2, 1965 [Aug. 12, 1964], No.32922/65. Heading B3D. A sanding and polishing machine comprises an abrasive belt 18 extending over a pair of guide rollers 12, 14 on a frame 2, a worksupporting table 20 on the frame between the rollers, a pad 78 on the side of the belt opposite the work-table, means 100, 110 for displacing a portion of the pad towards and away from the table, and means for urging the pad against the belt, the means 100, 110 for displacing the portion being adjusted so that the effective length of the pad corresponds to that of a workpiece to be abraded. The frame 2 is mounted on supports 4, 6 and supports the rollers 12, 14 for the abrasive belt and rollers 8, 10 for a back-up belt 16, rollers 10, 14 being driven by a motor 26 so that the speed of the abrasive belt is approximately twice that of the back-up belt. The work-table 20 is supported ;by screw jacks 22 which can be driven by a motor 24 for adjusting the height of the table which consists of a conveyer belt (32, Fig 1) driven by a motor over rollers (30) and a platform 34 Fig 4, beneath the pad. The pad is carried by a caul assembly consisting of a channel member (62, Fig 3) secured to a plate (64) and to thin rigid frames (66, 68) having inwardly turned lower flanges (70 72). A thin flexible metallic sheet (74) is disposed below the plate (74) and between the plate and sheet is a flexible :bag (96) having cells (98, Fig. 6) extending longitudinally of the plate. A canvas (78) is disposed below the pad 76 to prevent excessive wear of the pad and engages the surface of the backup belt (16), the ends of the canvas passing over rollers 80, Fig. 4, and being secured to clamps 82 which are adjustable by screws 86 to vary the tension of the canvas. Positioning plates (90, Fig. 5) are adjustable relative to the rollers by screws 94 to vary the slope of the canvas between the rollers and the pad. The means for displacing a portion of the pad at one or other end of the caul assembly comprises pairs of composite belts, each belt consisting of a tape secured to a chain. One of the pairs of composite belts has tapes 102 which extend between the flanges (70, 72) and the flexible metallic plate (74) and are entrained around shoes 106 and connected to chains 110 entrained about sprockets 128, sprockets on a shaft 122, and sprockets 104 and are connected to the opposite ends of the tapes. When the shaft 122 is rotated by a hand wheel 126, the chains are moved to press the flexible metallic plate 74 against the plate 64 compressing the inflatable end to a greater or lesser extent at the left-hand end as viewed in Fig. 4. The right-hand end of the pad is similarly adjusted by movement of the chains 110 of the other pair composite belt by rotation of a shaft 150. In operation, the bag 96 is deflated and the caul assembly is raised by an hydraulic motor acting on levers (46, Fig. 3) connected by brackets (48) to the channel member (62). A workpiece such as a veneer, is placed beneath the pad and the composite belts are adjusted so that the projecting part of -the pad (76) corresponds to the size of the workpiece. A work guide fence (50, 52, Fig. 1, not shown) is adjusted on the work table and air is supplied to the bag 96 at a controlled pressure. The caul assembly may be levelled by a hand wheel connected by a linkage (54, Fig. 1). The conveyer (32) is then started and the belts 16, 18 are driven by the motor 26. As a workpiece approaches the caul assembly, a stock feed switch 40 is operated which, after a time delay sufficient for the workpiece to move under the pad, operates the hydraulic motor to lower the caul assembly so that the pad presses the abrasive belt against the workpiece with a force which can be varied by adjustment of a linkage (58, Fig. 1) between the hydraulic motor and the caul assembly. As the trailing end of the workpiece moves under the-switch 40, the hydraulic motor raises the caul assembly after a delay sufficient for the workpiece to move under the abrasive belt.