Surface finishing machine

摘要

926,297. Fluid-pressure servomotor control systems. YATES-AMERICAN MACHINE CO. June 16, 1961 [April 14, 1961], No. 21801/61. Class 135. [Also in Group XXIII] A surface-finishing machine having an abrasive belt and means for automatically maintaining correct tracking of the belt comprises upper and lower rolls 11, 12 supporting the abrasive belt 13 above a work conveyer 17. A cross-beam 14 is supported at one end by an upstanding portion 15 of a main frame 16 and is supported at its other end by a member 18 pivoted by pin 20 on the frame 16 and having a bolt 21 adapted to engage a threaded socket in a bracket 23 secured to the end of the beam 14 so that the member 18 can be released and swung down to permit removal of the belt 13. The lower roll 12 is driven and its elevation is adjustable. The ends of the shaft 40 of the upper roll 11 are mounted in bearing-carrying brackets 41, 411 supported on the upper ends of pistons 42, 421 extending upwardly of power cylinders 43, 431 mounted in recesses in the ends of the beam 14. The roll 11 is thus urged upwardly to tension the belt 13. To equalize the movement a shaft 66 journalled in the beam 14 carries pinions 67, 671 engaging racks 68, 681 on the piston 42, 421. Vertical movement is limited by stops 70, 701 engaging slots 71, 711 in the pistons 42, 421. The bracket 411 is secured by a vertical pin 45 extending upwardly of the end of the piston 421; the bearing in the bracket 411 is selfaligning and is axially slidable in the bracket 411. The bracket 41 has a horizontal base with end sections 46, 461 to the bottom faces of which are secured plates 47, 471 riding on rollers 48, 481. These rollers are freely rotatable on shafts 49, 491 extending between upstanding guide plates 50, 501 disposed in parallel spaced relation on the top of the piston 42. Pairs of guide blocks 51, 511 secured on the ends of the top edges of the plates 50, 501 slidably engage the side edges of the end sections 46, 461 of the base of the bracket 41. Hold-down bars 52, 521 extending across the tops of the two pairs of guide blocks 51, 511 slidably engage the top surfaces of the end sections 46, 461 of the base of the bracket 41. A centre bearing roller 54 is mounted on a stub shaft 55 depending from the bottom of the bracket 41. A power cylinder 56 mounted between the plates 50, 501 has its piston 57 extending at opposite ends to engage angle brackets 59, 591 secured to the base of the bracket 41. Movement of the bracket 41 is limited in each direction by spring-pressed stop-pins 61, 611. The cylinder 56 is supplied through an electromagnetic valve (not shown) under the control of airoperated switches 62, 621 supported in a bracket 63 adjustably mounted on a bar support 64 having its ends secured on the beam 14. The operating fingers of the switches are disposed opposite spaced apertures in an air-control tube 65 secured by a bracket to the bracket 63 and connected to a compressed-air supply. When the belt 13 is tracking properly its edge lies between the switches 62, 621, the switch 62 being held closed by the unobstructed air stream and the switch 621 being held open due to the blocking of the air stream by the belt. If the belt 13 moves too far to the right, the switch 621 is closed by the uncovered air stream and the cylinder 56 is actuated to swing the roll 11 in the direction to cause the belt to move to the left; if the belt 13 moves too far to the left the switch 62 opens and the cylinder 56 is actuated to swing the roll 11 in the opposite direction.