Patent GB-1437908-A (GB)
Title: Betl grinding machine
IPC: B24B21/06
Filed: 1974-04-08
Abstract: 1437908 Grinding K HEESEMANN 8 April 1974 [21 April 1973] 15446/74 Heading B3D A belt grinding machine comprises a motordriven conveyer device 12 for a workpiece 10, an endless grinding belt 13 travelling above the conveyer transversely or longitudinally of the direction of movement of the workpiece, and a resilient pressure member 14 which is moved to press the grinding belt against the workpiece by a plurality of pressure units 16, 17, at least some 17 of the units being displaceable towards and away from the workpiece independently of the displacement of the pressure elements 53 of those units to adapt the pressure member to the form of the workpiece surface. The conveyer device may consist of a belt or pair of laterally adjustable chains 12 for conveying the workpiece 10, such as a chair seat, beneath the grinding belt 13 which is pressed against the workpiece by the pressure member 14. The latter has a resilient compression plate 54, preferably of steel, engaged by the pressure elements 53, layers of felt 55, foam rubber 56 and thinner felt 57, and a mat 58. The pressure elements 53 are mounted on the rods 21 of pistons 20 in the pressure units 16, 17. The units 16 are bolted to tubes 30, 31 connected to a beam 29 of the machine, the bolts being hollow so that low pressure in the tube 31 is connected by a passage 22 to lower chambers 33a of the units, and high pressure in tube 30 is connected by passages 24 and valves 26 to upper chambers 33b of the units. The units 17, however, have their upper and lower chambers 33b, 33a connected by flexible pipes 25a, 23a and valves 26 to the tubes 30, 31, the bodies 19 of the units being secured to guide rods 38 slidable in linear ball races 35 mounted in members 36 secured to the beam 29. The bodies 19 of the units 17 have extensions 40 which are connected by hydraulic lines or flexible cables 39 to respective pins or rollers 34a carried by pivoted arms 41 urged to an upper position by pressure devices 44. The rollers 34a engage the lower surface 10b of the workpiece which corresponds to the desired shape of the surface 10a to be ground, the movement of the rollers, through cables 39 effecting a corresponding movement of the bodies 19 of the units so that the pressure beam is deformed to the desired shape of the workpiece, e.g. concave, convex or flat. The upper surface 10a of the workpiece is sensed by rollers 27 associated with each of the pressure units 16, 17 whereby when the workpiece displaces a roller 27, a switch 51 is actuated to operate the associated valve 26 of unit 16 or 17 after a time delay so that high pressure is connected to chamber 33b of the unit to cause the pressure element 23 to press the beam, and hence the grinding bell; against the workpiece. In other embodiments, the rollers 34a scan the actual workpiece surface to be ground or a template, the resilient beam may be air-filled, the pressure units 16, 17, which are pneumatic or hydraulic, may be single or double acting or replaced by mechanical devices, and the displaceable units moved by further hydraulic cylinders or rack and pinion mechanisms.