| 摘要 |
1,179,088. Screw-and-nut mechanism. LANDIS TOOL CO. 6 March, 1968 [9 March, 1967], No. 10810/68. Heading F2Q. [Also in Division B3] A machine tool comprises a cutting tool 16 on a tool support 20, a work support S, means mounting the tool support for movement towards the work support, a feed mechanism for effecting the movement of the tool support including a feed screw 25 and nut 26, means 38 for effecting relative rotation of the screw and nut, means 50 for continuously stabilizing the relation between the screw and nut in one direction, and means for rendering the stabilizing means inoperative when the feed mechanism is actuated. The tool may be a grinding wheel or a cutting tool, such as a lathe tool, movable relative to a workpiece, or as described, a dressing tool 16 which is operable upon a grinding wheel 17. The dressing tool is mounted on a dresser bar 20 which is adjustable by the screw 25 and nut 26 on a slide member 15 mounted on a carriage 10 longitudinally movable in the support S by a piston-and-cylinder device 11, 12 controlled by a reversing valve 14. The nut 26 is secured to the bar 20 and the screw is rotated by a wheel 32 meshing with a worm 33 which can be rotated by a handle 35 or a pawl-and-ratchet 36 operated by a piston 38 movable in a cylinder 41 by fluid pressure from a solenoid-operated valve 48. The stabilizing means 50 consists of a cylinder 51 having a piston 52, the rod 53 of which is connected by a rod 57 to the dressing bar 20, fluid supply to the rod side of the piston being controlled by a valve 61. During a dressing operation, the valve 61 supplies fluid to the rod side of piston 53 so that backlash between the feed screw 25 and nut is taken up. When feed of the dressing tool is to be effected, the valves 48, 61 are simultaneously operated so that the supply to piston 53 is cut off to release the screw and nut and is connected to cylinder 41 to move pawl 38 to effect a feed of the dressing tool. |
