Patent GB-1421612-A (GB)
Title: Buffing machine for the buffing of skins or like materials
IPC: C14B1/46
Filed: 1973-04-25
Abstract: 1421612 Buffing LUIGI RIZZI & C SpA 25 April 1973 [27 May 1972] 19717/73 Heading B3D [Also in Division G3] A machine for buffiing skin or like material P comprises a buffing roller 3, a rocking lever 8 carrying a skin driving roller 1 and pivoted to move the axis of the roller towards and away from the axis of the buffing roller, an hydraulic thrustor 11, 13 for the driving roller and an adjustable hydraulic valve 16, the spool 22 of which is actuated in such a manner that with every movement of the roller axis there is a corresponding movement of the spool to supply pressure fluid to the thrustor to restore the driving roller to a predetermined position. The buffing roller 3 is covered with abrasive material or drives a continuous strip of abrasive material tensioned by an idler roller. The buffing roller 3 is driven in the direction B at a greater speed than the roller 1 is driven in the direction A, the driving roller 1 having an elastic facing and co-operating with a retaining roller 2, which is mounted on an adjustable arm 4, to feed the skin past the buffing roller. The roller 1 is mounted on the lever 8 which is pivotable about an axis 9 and has a projection 10 engaged by the rod 11 of a piston 12 in a cylinder 13 connected by conduits 14, 15 to the valve 16. The latter is in adjustable relation to the frame of the machine by rotation of a handwheel 20 and has a spool 22 which closes ports 14b, 15b leading to pipes 14, 15 connected to the cylinder 13. The spool is urged by a spring 23 into engagement with an eccentric 28 carried by an arm 29 on the end 8b of the lever 8. The eccentric is connected to a lever 33 movable by the rod 32 of a piston 31 in a cylinder 30 in the arm 29, the cylinder being connected by pipes 37, 38 to a valve 39. An extension 36 carries a stop 34 for the lever 33 movable into various positions 35. In operation, the position of the valve 16 is adjusted by rotation of the handwheel 20 so that the ports 14b, 15b are closed when the distance between the driven and buffing rollers 1, 3 corresponds to the desired thickness of the skins to be buffed. During buffing, an increase in the thickness of a skin causes lowering of the lever 8 in the direction of arrow C and a rise in the position of the eccentric 28 permitting the spring 23 to move the spool 22 and open port 15b so that pressure fluid from port 24 passes through conduit 15 to act on piston 12 and restore roller 1 to its set position, the eccentric 28 moving the spool to close the ports 14b, 15b. When the end of the skin passes beyond the roller 2, an operative or automatic scanner operates solenoid-operative valve 39 so that piston 31 is moved to the right to a position determined by engagement of lever 33 with stop 34 and the spool 22 is displaced downwardly connecting port 156 to exhaust 25 and port 14b to the source 24. The piston 12 and roller 1 thus moves downwardly and the eccentric 48 is raised to establish a position of equilibrium of the spool 22 resulting in an increase in spacing between the rollers 1, 3 to avoid turning over of the freed end of the skin and buffing of the wrong side thereof.