GB826970A - Improvements relating to workpiece gauges - Google Patents

Abstract

826,970. Gauge-testing apparatus. JONES & SHIPMAN Ltd., A. A., and HOULDSWORTH, J. Oct. 4, 1957 [July 4, 1956], No. 20669/56. Class 106 (2). [Also in Group XXIII] A method of checking and correcting the accuracy of a gauge of the kind having spaced jaws, feelers or points a, b, comprises alternately placing a test dimension of larger size and a test dimension of smaller size than a required datum size between the points and using the resultant reactions of the gauge to apply a correction thereto. The gauge has fixed points b, c, and a movable point a secured to a spring- urged plunger e, which is carried in an axiallymovable sleeve d disposed in a gauge head 6, and has elements arranged in association with the sleeve d, to emit electrical or pneumatic size-indicating signals. The gauge head 6 is resiliently-mounted by means of a crank 30, screw 36 and springs 31, 32 from a plate 34 carried on pivoted arms which swing the head between a lower position, wherein the head gauges a cylindrical workpiece W being ground by a wheel G and automatically controls the withdrawal of the wheel from the workpiece when the latter has been ground to size, to an upper position for checking and correction of the gauge after receipt of a signal that a preselected number of workpieces have been ground or that the grinding-wheel has worn a predetermined amount; the same signal may also be used to actuate a mechanism for trueing the wheel while the gauge is being checked. The signal actuates a series of electromagnetic relays and limit switches which withdraw the control of the machine from the gauge when the latter is moved to its upper position and place the gauge under the control of checking and correcting apparatus. This apparatus comprises a test-piece 1, which is oval in section and has a major diameter greater than and a minor diameter smaller than the diameter to be ground on the workpiece and is mounted on an arm 2 movable about a pivot 3 by energization of a solenoid SOL4 so as to place the test piece between the points of the gauge. The test piece is then rotated by an electric motor through 180 degrees and stopped. If the gauge is correctly set and over and under-size signals have therefore been emitted from the elements associated with the plunger e, the test piece is rotated a further 180 degrees to confirm that over and under-size signals were emitted before the test piece is withdrawn from the gauge by de-energization of the solenoid SOL4, the gauge swung to its lower operative position and the grinding-machine again placed under the control of the gauge. If, however, the gauge is incorrectly set and two under-size or two oversize signals emitted or one signal is considerably larger than the other during the initial 180 degrees rotation of the test piece, either a solenoid SOL1 or a solenoid SOL2 is energized to actuate one or other of pawl-and-ratchet devices 19, 20 or 21, 22 to rotate a worm engaging a wheel formed as a nut on the sleeve d to axiallyadjust the latter in the gauge head. A further solenoid SOL3 is then energized to cause a hammer 7 to strike the head to overcome frictional inertia in the mechanism which is also provided with springs on the shaft of the worm and the sleeve d to eliminate backlash. The respective solenoid SOL1 or SOL2 will be energized once during the stop period following each 180 degrees of rotation of the test piece until an oversize signal and an undersize signal have been received. The test piece is then rotated a further 180 degrees as before to ensure a repetition of over and under-size signals before the head is swung to its lower operative position. A limit may be set to the number of consecutive operations of the solenoids SOL1 or SOL2, a counting mechanism illuminating a lamp to indicate that excessive adjustment has become necessary. In an alternative embodiment, the corrective movements of the solenoids SOL1, SOL2 are operative on the zeroing adjustment of the device which controls the grinding-machine, from the amplified sizeindicating signals from the elements associated with the plunger e. Manually-operated means are provided to permit re-setting the gauge and to assist initial setting-up and maintenance. Coolant may be supplied to the test piece and workpiece to overcome the effect of temperature differences between them. Specification 810,316 is referred to.