Patent GB-967085-A (GB)
Title: Improvements in and relating to grinding machines
IPC: B24B41/06
Filed: 1961-11-22
Abstract: 967,085. Grinding. LANDIS TOOL CO. Nov. 22, 1961 [Dec. 2, 1960], No. 41701/61. Heading B3D. A machine for grinding the external peripheral surface of a ring-like workpiece comprises a rotatable face plate, means for supporting the workpiece at peripherally spaced points on the external peripheral surface so that the workpiece moves radially as it is ground to a smaller diameter, a workpiece holding means, the holding means being capable of radial movement relative to the face plate, corresponding to the radial movement of the workpiece and including a pressure cylinder housing a piston resiliently loaded towards the face plate, and one end of an arbor, which arbor has a projection for supporting a ring-like workpiece on an internal surface of the latter to move the workpiece from a magazine to the face plate, there being a fluid passageway for supplying fluid under pressure to those faces of the piston and the arbor remote from the face plate, whereby, in use, fluid acting on the face of the arbor urges a workpiece into engagement with the face plate and, simultaneously, against the resilient loading of the piston, forms a fluid bearing between the arbor and the piston thereby permitting rotation of the arbor, relative to the piston. A housing 15 has a tapered portion 16 mounted in a tapered bore 17 in an arm 10 and has a threaded portion 20 by which it is secured to the arm 10. Pressure fluid, e.g. air, is directed to a passage 30 in the housing 15 through a connector 25. In a recess 31 in the housing 15 is a piston 32 having a conical portion 33. Within and attached to the piston 32 is a short cylindrical member 40 in which is slidably mounted a piston 41 having a recess 42 containing a spring 43 acting between the end of the recess 42 and the end portion 45 of the member 40. The piston 41 has a head 50 slightly smaller in diameter than the inside of the piston 32. A restricted passage 46 in the part 45 admits pressure air from the passage 30 into the recess 42 and a larger passageway 47 in the head 50 permits discharge from the recess 42. A work-engaging arbor 60 has at its outer end a portion 61 of a diameter slightly smaller than the inside diameter of the workpiece 70 and also has a conical flange 71 shaped to coact with the inner face of the conical portion 33 of the piston 32 to centre the arbor 60 relative to a workpiece which it is to remove from a work-feeding shoot. The flange 71 has a recess 72 formed therein to provide a chamber with the head 50 of the piston 41 serving as one side thereof. Pressure air supplied through the passageway 47 separates the arbor 60 from the piston 41 by urging the piston to the right against the spring 43 leaving the arbor 60 to rotate with the workpiece free of frictional resistance from the piston 41. A sleeve 80 slidably mounted on the arbor 60 engages and holds a workpiece against a face plate 75. Spaced flanges 81, 81 provide a groove 82 by which the sleeve 80 may be moved endwise to remove the workpiece 70 from the arbor 60. The flange 81 at the end of the sleeve 80 is relieved so that only an annular portion 83 engages the face of the flange 71 of the arbor 60. A work-supporting member 90 attached to the housing 15 has formed thereon work-engaging surfaces 91, 92. For ejecting a workpiece 70 from the portion 61 of the arbor 60 a plate 100 has a fork 101 engaging the groove 82 of the sleeve 80, the plate 100 being attached to a plunger 105 slidable in a sleeve 106 in the arm 10, the plunger being loaded by a spring 109 and actuated by a cam (not shown). A guide pin 115 on the arm 10 passes through an opening 116 in the plate 100. The head 108 of the plunger 105 is in operative relation with a safety signal transmitting member 110 such as a limit switch or air nozzle which prevents advance of the grinding wheel 120 if the arm 10 is down with no workpiece in the machine and the sleeve 80 lying in the path of the grinding wheel. Operation.-When the surfaces of parts 71, 33 are in contact arbor 60, 61 is held in axial alignment with a workpiece in a feed shoot to engage the workpiece. Piston 32 is moved to the right. Initially the arm 10 swings downwardly to place the workpiece in operative relation to the face plate 75, the spring 43 urging the piston 41 against part 71. When the arm 10 reaches the operative position, it closes a limit switch 8LS energizing a relay 14CR energizing a solenoid 6 actuating a valve 130 to direct pressure air through a supply line 24 to the passage 30, so advancing the piston 32 to the left and separating the conical parts 33, 71. Pressure air from the passage 30 passes through the restricted passage 46 into the recess 42 in the piston 41 and through the passageway 47 into the chamber formed between the head 50 of the piston 41 and the recess 72 in the part 71. This pressure moves the piston 41 to the right, separating it from the part 71, the flow of air from between the piston 41 and the part 71 providing a thin air bearing which permits substantially frictionless rotation of the arbor 60, 61 with the workpiece 70. The space between the surfaces of parts 33, 71 permits radial movement of the arbor 60, 61 to follow the workpiece as its diameter is reduced. The pressure acting on the piston 41 operates a pressure switch 3PS energizing a relay 17CR energizing a solenoid 7 actuating a valve 135 to admit pressure air to a cylinder 140 to advance the grinding wheel 120 for a grinding operation.