Patent GB-960467-A (GB)
Title: Coated abrasive belt machine
IPC: B24B21/00
Filed: 1961-09-22
Abstract: 960,467. Abrasive belt machines. NORTON CO. Sept. 22, 1961 [Nov. 10, 1960], No. 34082/61. Heading B3D. [Also in Division G3] A coated abrasive belt machine comprises a frame, a contact roll and an idler roll for supporting and driving a coated abrasive belt, mounted on the frame for rotation and for reciprocal movement in directions along their respective axes by means allowing the rolls to be so positioned as to facilitate the training over or removal from the rolls of an abrasive coated belt, means for driving one of the rolls, and a reciprocating device associated with one of the rolls and arranged to effect reciprocal movement of the roll in directions along its axis and transversely to the direction of travel of the belt and thereby indirectly effect reciprocal movement of the other roll through the forces transmitted by the abrasive belt. General.-A machine for buffing tanned hides comprises a frame 10 on which are mounted a feed roll 11 and a pressure roll 12. The feed roll 11 is adjustable by means 15 and is belt driven from a motor 17. The pressure roll 12 is adjustable by means 14. A conveyer belt 18 driven by the motor 17 conveys dust and debris arising from the abrading operation to an exhaust duct 19. In place of the conventional abrasive drum of the buffing machine there is provided a contact roll 20 belt driven from the motor 17. The shaft 20<SP>1</SP> of the roll 20 is mounted in self-aligning bearings 22, 23, the bearing 22 being permanently mounted to frame 10 and the bearing 23 being held in position by a quick release outboard latch 24 and stops 25, 25. A reciprocating mechanism 43 and return spring 44 are provided on the shaft 20<SP>1</SP>. The bearing 23 is movable, once latch mechanism 24 is released, by the air lift device 26 actuated by air cylinder 27 mounted on cantilever beam 28 attached at one end to a column 30 permanently affixed to frame 10. Also on beam 28 is a tension air cylinder 31 operating a frame 34 having bearings 33, 33 for the shaft 32<SP>1</SP> of idler roll 32, means 36, 36 being provided to permit axial reciprocation of the shaft 32<SP>1</SP>. Connected by linkage 37 to the frames 30, 34 are an automatic belt tracking assembly 38 and a manual tracking adjustment 39 which actuate tracking air cylinder 40. A hood 41 is provided. A coated abrasive belt 42 extends round contacroll 20 and idler roll 20. Contact roll reciprocating assembly.-The shaft 54, Fig. 4, of contact roll 20 is mounted in a self-aligning bearing 50 fastened to the machine frame 52 and is driven through pulley 60 at about 1100 R.P.M. A cam plate 51 secured to the frame 52 is slanted to form one wall of a bearing race, the other wall of which is formed by a thrust bearing 53 mounted around shaft 54 with the plane of the bearing substantially normal to the axis of shaft 54 and driven at about 400 R.P.M. by a pulley 55 from the main drive motor. Mounted within the bearing race so formed is a single ball bearing 56. Roller bearings 57, 57 are incoporated in the unit. Mounted around shaft 54 inboard of its bearing 50 are a thrust bearing 58 and spring 59. The cam plate 51 thrust bearing 53 and ball bearing 56 are enclosed in a housing (not shown). Outboard latch assembly.-To permit easy and quick freeing of one end of the contact roll so as to change abrasive belts, a latch 70, Fig. 8, pivoted at 74 to frame 75 has its end 71 mating in a tapered fit with a tapered block 72 fixed to the base of the outboard bearing 73, the latch being held in closed position by a locking screw 76 operated by handle 77. The latch is opened to permit the bearing 73 and contact roll shaft 78 to be lifted by the contact roll air-lift device. Stops 80, 81 assist in re-positioning bearing 73 when the contact roll is allowed to drop back into place. Contact roll air-lift assembly.-The mechanism whereby the outboard end of the contact roll is lifted to permit changing the abrasive belt consists of a support member 90, Fig. 10, fixed to the beam 28 and having a tapering wedgeshaped upper surface 91. A slot extends through the member 90 to permit passage of a hook member 93, whose straight end is fixed to the piston of a double-acting air cylinder 95 and whose curved end engages the shaft 97 of the contact roll between the end of the roll and the outboard bearing. Once the latch mechanism described above has been released, the cylinder 95 is actuated and the shaft 97 is drawn by hook member 93 up the inclined surface 91, thus providing an uninterrupted passage round the outboard end of the contact roll and the idler roll to permit easy removal and replacement of an abrasive belt. An hydraulic cylinder may be used in place of an air cylinder. Automatic belt tracking assembly.-The assembly for automatically keeping the abrasive belt centred on the idler and contact rolls comprises, Figs. 12 and 13, mercury switches 100, 101 actuated by air paddles 102, 103 co-operating with air jets. In normal operation outboard paddle 102 is depressed by its air jet and inner paddle 103 is raised as its air jet is interrupted by the abrasive belt 42. If the belt 42 shifts outwardly, paddle 102 rises due to interruption of its air jet and switch 100 is actuated, whereby the air cylinder 40 lifts one end of the idler roll 32 causing the belt 42 to track back. If the belt 42 shifts inwardly, paddle 103 is depressed by its air jet and actuates switch 101 so that air cylinder 40 makes the necessary correction. Manual belt tracking adjustment assembly.- The air cylinder 40, Fig. 14, can be raised or lowered by adjusting knobs 110, 110<SP>1</SP>. Idler roll reciprocating assembly.-Means positioned at each end of the idler roll permit it to be axially reciprocated with the contact roll through force transmitted by the abrasive belt. The idler roll 120, Fig. 15, which is preferably light, e.g. aluminium tube coated with chromium, is mounted on a shaft 121 journalled in a roller bearing 122. The end of the shaft 121 contacts a thrust bearing 123 backed up by a spring 124 adjustable by a screw 125. Operation.-A belt coated with abrasive of 80-400 grit is driven, by a 15 H.P. motor, at 3700 ft./min. A contact roll surfaced with rubber of about 35 Durometer hardness is preferably used. The pressure roll is steel, and the feed roll is coated with rubber of about 15 Durometer hardness. The axial reciprocation of the rolls is at 200 cycles/min. with a travel of about <SP>7</SP>/ 16 th inch. The controls are preferably interlocked electrically so that the belt must be tracking and under tension before driving power can be applied.