GB1202070A - Belt grinding machine - Google Patents

Abstract

1,202,070. Grinding. K. HEESEMANN. 17 Nov., 1967 [26 Nov., 1966], No. 52448/67. Heading B3D. A belt grinding machine comprises an elastically flexible load beam extending over the entire operative length of an endless grinding belt 12, the effective pressure-applying surface 19 of the beam being suspended for elevational control from support elements 18a, 18b distributed at intervals along the beam and attached to elevationally movable carrier means consisting of transverse beams 56 mounted on push-rods 43 operable by a pressure medium, the rods being associated with delay means responsive, on the one hand, to the difference in time between the instant of response of sensing means 31 to the passage of the leading end of a workpiece 11 and the instant grinding begins, and, on the other hand, so the difference in time between the instant of response of the sensing means at the passage of the trailing end of the workpiece and the instant grinding terminates. The workpieces 11 are fed by a belt-conveyer 13 below the grinding belt 12 which runs under a mat 22 fastened at one end to the beam, the mat being backed by a pad 21 of felt or sponge rubber, an elastic steel plate 19, and a flexible tube 20 which receives pressure air and abuts the lower face 17 of the beam. The plate 19 is carried at spaced points along its length by tie-rods 18a, 18b secured to levers 25, 26 fixed to shafts 57. A control lever 56 is carried by each shaft 57 and has a roller 55 positioned above the rod 43 of a piston 41 which carries a cam 44 for cooperation with rollers 60, 61 on a pawl 61 movable against a spring 63. The upper surface of the piston 41 is supplied with a constant air pressure through connection 40, and the lower surface is connected through a pipe 48, with air pressure or exhaust by a valve 38 which is supplied with pressure from an adjustable throttle valve 50 and is actuated by rocking of a lever 36 by a cam 29a moved when a lever 29 carrying a roller 31 is displaced by a workpiece 11. When the leading edge of a workpiece engages the roller to rock lever 29, valve 38 is actuated to connect pipe 48 from the lower surface of the piston to exhaust and thus lower rod 43. When the cam 44 engages the roller 64 and rocks pawl 61 against the spring 63, roller 60 is moved to permit lowering of the levers 56 by the pressure in the flexible tube 20 acting on the steel plate 19 and tie-rods. The arrangement of cam 29a and the rollers 60, 64 provides a time delay between the contact of the workpiece with the roller and the lowering of the associated part of the pressure beam to avoid over-grinding of the edge of the workpiece. Each lever 29 carries an antrainment arm 39 which extends across the adjacent levers 29 so that when a lever 29 is moved by contact with a workpiece, the adjacent levers are moved by the entrainment arm but to a lesser extent so that the parts of the pressure beam associated with those levers are lowered by a lesser amount than that part lowered by the lever contacted by the workpiece. The difference in delay times necessary to prevent over-grinding of the leading and trailing edges is provided by the retaining of levers 56 until the rods 43 have completed part of their downward movement. In other embodiments photo-cells or magnetic valves control the raising and lowering of the surface of the beam.