Patent GB-912465-A (GB)
Title: Incremental linear actuator
IPC: B23Q7/04
Filed: 1959-10-12
Abstract: 912,465. Grinding. FAIRCHILD CAMERA & INSTRUMENT CORPORATION. Oct. 12, 1959 [Oct. 30, 1958], No. 34471/59. Class 60. [Also in Groups XXII and XXIX] A device for imparting incremental translation to a machine part or the like comprises an elongate drive-rod, first and second clamp means operable to grip the rod at different locations thereon, compression means positioned on the rod at a location between said first and second clamp means and operable to compress the rod in a direction transverse of the length thereof to effect lengthwise elongation of same, and control means connected to said first and second clamp means and to said compression means to operate such three means sequentially. A workpiece 14, Fig. 1, supported on a work-holder 16 mounted on base 10 is ground by a grinding-wheel 18 carried by a member 12 movable on the base 10. A steel rod 24 secured at 22 to the member 12 passes through a housing 26, on which are housings 28, 30, 32. The housing 28 contains a first gripper 52, Fig. 3, the interior of which is connected to the output of a pressure intensifier 58, the input of which is connected through normally closed valve 56 with a fluid pressure line 54. The housing 32 contains a second gripper 60, the interior of which is connected to the output of a pressure intensifier 64, the input of which is connected through normally closed valve 62 with the line 54. The housing 30 contains a compression cylinder 66, the interior of which is connected to the output of a pressure intensifier 76, the input of which is connected with the line 54 through normally closed valve 74 and pressure regulator 70 operated by handle 42, a pressure indicator 44 being provided. The valves 56, 62, 74 are opened in the desired sequence by a cam 78 operated by handle 40. The pressure intensifier 58 within housing 28 comprises a flexible diaphragm 108, Fig. 5, supported by a piston 110. When air pressure (from line 54) is admitted to the space 106 in housing 28 the stem 114 of piston 110 pressurizes oil in cylinder 116 communicating with a chamber 96 surrounding the flexible inner wall 94 of the gripper 52. The piston is urged by a spring 112 into an upper position in which ports 118 are uncovered to permit replenishment of the oil in cylinder 116 from a reservoir 102. The pressure intensifier 64 within housing 32 is identical with intensifier 58. The pressure intensifier 76 within housing 30 is identical with intensifier 58 but the liquid cylinder communicates with the annular space 134 surrounding the rod 24 whereby the rod is compressed radially. A feed cycle results from rotation of the cam 78 in one direction through successive positions in which (1) grippers 52, 60 operative and compression unit 66 inoperative, (2) gripper 60 rendered inoperative, (3) compression unit 66 rendered operative, whereby rod 24 elongates away from gripper 52, (4) gripper 60 rendered operative, (5) gripper 52 rendered inoperative, (6) compression unit 66 rendered inoperative, whereby rod 24 contracts towards gripper 60, (7) gripper 52 rendered operative and the parts are all as in (1). Rotation of the cam in the opposite direction effects movement of the rod 24 to the left. In a modification, Fig. 4, the rod 86 has, within the compression unit 66, a reduced diameter portion 88 whereby the elongation produced by radial compression is augmented by that caused by fluid pressure acting on the annular faces 90, 92. In a modification, Fig. 2, a rod 48 secured to base 10 at 50 passes through a housing 46 attached to the movable member 12. Coarse feed may be effected by a lead-screw, the fine feed being effected by an actuator as above, e.g. under the control of a size gauge.