GB1273050A - Method and apparatus for producing a relative micrometric movement between two members of a precision machine tool - Google Patents

Abstract

1,273,050. Gauging; grinding. M. G. CHANCEL. 22 Sept., 1969 [20 Sept., 1968], No. 46555/69. Headings B3B and B3D. A method of producing relative micrometric movement between two members of a precision machine tool, e.g. a grinding machine, comprises adjusting the pressure of hydraulic fluid within a first deformable element 1 bearing against the two members until a second deformable element hydraulically interconnected with the first deformable element, and whose interior contains fluid which is subjected to the same pressure as the first deformable element, is deformed to an extent which is representative of the desired relative movement, the deformation of the second deformable element being used to gauge the movement produced by the first deformable element. Apparatus for carrying out the method comprises a pressure generator or multiplier 3 connected with the elements 1 and 2, a float controlled regulating means 15, and a setting arrangement 8 which carries the regulating means 15 and is movable along a graduated scale 9. The float 14 is moved, via a hose 13 by a liquid 12 in a reservoir 10 and acted upon by a pressure fluid that also actuates the multiplier 3. A bleed nozzle 17 leads from the reservoir 10 and its outlet is controlled by the movement of the control element 2. A column of liquid 23 is used to stabilize the pressure in the line feeding the reservoir 10. In operation the arrangement 8 may be set for a given displacement of the workpiece 6. For a given setting, high pressure fluid from the multiplier 3 expands the control element 2 and pressurizes the elements 1, the position of the control element determining the amount of fluid escaping from nozzle 17. This in turn provides a pressure in the reservoir 10 which supports a head of fluid in the hose 13. Should events occur at the workpiece to cause the control element 2 to expand, then the orifice 17 will be restricted causing a pressure rise in the reservoir 10 which will raise the float 14 and allow pressure fluid, e.g. air, to escape to atmosphere. This will reduce the pressure acting on the multiplier 3 which will correspondingly reduce the pressure in the control element 2 to re-establish correct flow through the nozzle 17 and restore equilibrium in the circuit. In a second embodiment (Fig. 3, not shown) a setting is achieved by moving a motor-driven balance weight along a pivoted balance arm (31). The free end of the arm moves between two valves which control the pressure flow to the multiplier 3 and to a pressure diaphragm (32) to balance the arm at each setting. In a third embodiment (Fig. 4, not shown) high pressure for the elements 1 and 2 is provided by an hydraulic pump and accumulator arrangement. The nozzle 17 is supplied with liquid under a constant head. The arrangement is set by adjusting the height of a reservoir and float 14, 15. The deformable elements 1 may be situated in varous places in a machine tool, e.g. supporting a chuck, or other work fixing means; the headstock, tailstock or tool holder; for correcting or monitoring the deformation of bases; for compensating tool wear, e.g. grinding wheels or lathe tools; for obtaining slight curvature on paper making rolls; for steadies for lathes and grinding machines; for removing a tool from a workpiece after a cutting operation for a return stroke; for mounting a spindle for longitudinal adjustment or compensation for its loading or temperature.