Patent GB-1334256-A (GB)
Title: Method of and apparatus for rapidily abrading workpieces
IPC: B23Q1/50
Filed: 1970-11-09
Abstract: 1334256 Grinding TIMESAVERS Inc 9 Nov 1970 [18 May 1970] 53264/70 Heading B3D A surface abrading machine comprises an endless belt 7 around a contact drum 9, Fig. 2 and 3, which is rotatable about a fixed axis, a work support member 36 movable towards and away from the drum, work feeding means acting on the member, and elastic biasing means 50 acting between the member and a fixed part of the machine and storing mechanical energy for urging the member towards the drum. The belt runs around the contact drum 9 and a roller 8, the latter being carried in bearings 15 of a yoke 16 which is acted upon by a pneumatic cylinder 17 to tension the belt and oscillated about the axis of the cylinder by a motor 18 to shift the belt back and forth along the drum 9 to effect uniform wear of the belt. The contact drum is carried by bearing 14 depending from a beam 11 which is secured at one end to a side wall 12 of the machine and at the other end has a stub shaft 23 clamped between an upper adjustable jaw and an hydraulically-operated lower jaw, the jaws being in an arm which can be swung to an inoperative position to provide access to the drum. Adjustment of the upper jaw permits positioning of the rows of the contact drum in a horizontal or slightly inclined position. The drum is driven by a belt drive 31 from a motor 30. Spent abrasive material can pass through an opening 32 into a cyclone-type separator 33. The work support consists of a pair of turrets 36 carried by a table 37 which can be indexed in 180 degree steps to move the turrets between operating positions and loading positions. The table 37 is supported by a thrust bearing 47, Fig. 5, and is indexed by a motor 48, the bearing being carried by a plate 38 which can be raised and lowered to effect feed of the work support by interconnected screw jacks 41 driven by a motor 46. Each turret consists of a plate 64, Fig. 7, on which a workpiece can be mounted and which is rotatably mounted by a bearing 57 on an arm 51, the arms of both turrets being mounted for pivotal movement on a shaft 56 carried by pedestals 52 on the turntable 37. The turrets are secured to shafts 58 in the arms and are rotatable by worm gearing 60, 61 driven from motors 62. An elastic biasing means 50 is disposed between. each arm 51 and the turntable 37 and consists of a generally cylindrical rubber bag having one end secured by a ring 71 to a disc 70 on the arm and the other end secured by a clamping ring 73 to the turntable. The bags can be charged with air under pressure through a connection 76. Upward pivotal movement of the turrets is limited by stops 79. In operation and with the bags 50 charged with air, a workpiece is mounted on a turret which is then indexed by rotation of the turntable to be below the contact drum. The turntable is elevated at a slow speed by the screw jacks 41 until the workpiece just engages the belt and then again indexed. A control for the screw jacks is set to a desired feed depth, say 0À125 inches. Thereafter, with the turret rotating, the turntable is again indexed to bring the workpiece below the belts and on screw jacks operated to practically instantaneously raise the turntable through the desired feed distance, the turret and its arm 51 being pivoted downwardly by the force of the workpiece engaging the belt against the resistance of the pressure in the bag 50 of the elastic biasing means. The pressure acts to press the turret upwardly to the position determined by the stops 79. After one or two revolutions of the turret, the workpiece is abraded to the desired depth of cut and the speed of rotation of the turret is then increased to improve the finish of the surface. After lowering of the turntable by the jack screw, the turntable is indexed for abrading of a workpiece mounted on the other turret. In another embodiment, the jack screws are only used to set the height of the turntable and hydraulic cylinders are provided to urge the turrets downwardly against the pressure in the elastic biasing means during indexing of the turntable. Upon release of the pressure in the cylinders, the elastic biasing means effects the feed of the turret. In a further embodiment, the turrets are raised by air supported from a source conrolled by a valve.