Patent GB-1179176-A (GB)
Title: Belt Sanding and Polishing Machine.
IPC: B24B21/10
Filed: 1967-01-24
Abstract: 1,179,176. Sanding. CARBORUNDUM CO. 24 Jan., 1967 [16 Feb., 1966], No. 3534/67. Heading B3D. A sanding and polishing machine comprises: (a) a base, (b) an upper frame mounted on said base, (c) an abrasive belt mounted for movement on said upper frame, (d) a lower frame mounted on said base and spaced beneath said upper frame, (e) a conveyer means supported by said lower frame for advancing a workpiece through a path of travel toward said abrasive belt and normal to said movement of said abrasive belt, (f) aligning means mounted on said upper frame forwardly of said abrasive belt and extending transversely of said path of travel for interrupting the advancement of said workpiece until the leading edge thereof abuts said aligning means and is disposed parallel thereto, and (g) power means for elevating said aligning means to allow the workpiece to pass thereby A frame 10, Fig. 2, supported by a base comprising pedestals 12, 14 mounts pulleys 16, 18 for an endless back-up belt 20 and pulleys 22, 24 for an endless abrasive belt 26. Pulleys 18, 24 are driven by a motor 28, the linear speed of the back-up belt 20 being approximately half that of the abrasive belt 26. A frame 30 is supported by screw jacks 32, 34 on the pedestals 12, 14, the jacks being operated by a motor 36. The frame has, at opposite ends, rollers (38), (40) about which is trained an endless conveyer belt 42. A baseplate 44 mounted on the frame supports the active run of belt 42. The active runs of belts 20, 26 are urged against a workpiece by a caul assembly 46 having brackets 62 connected to levers 58, pivoted in bearings 60 on frame 10; the levers 58 are connected by a bar (56) raised and lowered by an hydraulic cylinder (54). The caul assembly 46 and belts 20, 26 are enclosed in a housing 48, dust-laden air being drawn out of the housing through outlets 50, 52. Vertically adjustable rollers 66 mounted along the front and rear of housing 48 urge the workpiece against the conveyer belt 42. A work guide fence (64) secured at one end of the conveyer frame 30 extends transversely of the run of belt 26 for guiding the advance of the workpiece on conveyer belt 42. A second force may be secured at the other end of conveyer frame 30. To ensure that the leading edge of a workpiece will be in alignment in a direction parallel to the longitudinal axis of abrasive belt 26 a stop gate assembly 68 is provided, being mounted between brackets 70, 72 secured to frame 10 and spaced upwardly from conveyer belt 42. Pneumatic cylinders 74, 76 secured to the brackets contain pistons having rods secured to a support 86 extending substantially along the width of conveyer belt 42; upward extensions of the rods carry bevelled collars 92, 94, upward movement of which closes normally open limit switches 154, 156 mounted on the brackets 70, 72. The support 86 has a longitudinal bottom slot 100 receiving rectangular, relatively thin, vertically depending stop-bars 102 having integral shoulders 104 to limit their downward travel. A member 106 of U-shaped cross-section and a member 108 of inverted L-shaped cross-section extend along the bottom of the stop gate assembly and are secured to the brackets 70, 72; the bight portion of member 106 and the longer leg of member 108 are spaced to form a slot receiving the stop-bars 102. A rail 110 secured to the edge of the shorter leg of member 108 carries brackets 112, 114 adjustable along the length of the rail. Pneumatic cylinders 118, 120 secured to the brackets 112, 114 contain pistons having rods to the lower ends of which are rotatably secured rollers 126, 128; upward extensions of the rods carry bevelled collars 134, 136, upward movement of which closes normally open limit switches 142, 144 mounted on the brackets 112, 114. Operation.-A workpiece, e.g. a veneered wood panel, is placed on conveyer belt 42. Assuming the leading edge of the workpiece is not parallel with the stop gate assembly, a portion of the leading edge will contact one of the rollers 126, 128 and raise it to close its associated switch 142 or 144; when the other roller is engaged by another portion of the leading edge, the other of the switches 142, 144 is closed. Switches 142, 144 are in series and when both are closed, a timer (210) is energized, maintaining the stop gate assembly down for a predetermined time until the workpiece abuts stop-bars 102 whereby the workpiece is aligned. At the end of this time, a solenoid (188) is energized, actuating a valve (170) to supply pressure to the lower ends of cylinders 74, 76 and put the upper ends to exhaust; support 86 is thus raised, allowing the workpiece to advance beneath the abrasive belt 26. Actuation of the cylinders 74, 76 closes switches 154, 156, thus (a) energizing a solenoid (194) actuating a valve (192) to supply pressure to the upper ends of cylinders 118, 120 to exert pressure on the workpiece to maintain its alignment and (b) energizing a relay to control the exact instant of caul assembly lowering dependent on the linear speed of the conveyer belt. When the rollers 126, 128 drop off the trailing edge of the workpiece switches 142, 144 open, solenoid (188) is de-energized and valve (170) is actuated to supply pressure to the upper ends of cylinders 74, 76 and put the lower ends to exhaust so that support 86 is lowered; the stop-bars 102 ride on top of the workpiece until it has passed, when they descend by gravity to down position in readiness for the next workpiece. Lowering of the support 86 opens switches 154, 156, de-energizing solenpid (194), actuating valve (194) to put the upper ends of cylinders 118, 120 to exhaust so that the next workpiece can easily raise the rollers 126, 128. Two workpieces of shorter lengths and substantially equal widths may be aligned in a side-by-side relationship by means of the stop gate assembly prior to approaching the caul assembly.