Patent GB-363695-A (GB)
Title: Improvements in machines for precision grinding
IPC: B24B49/02
Filed: 1930-06-20
Abstract: 363,695. Grinding. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Norton Co.; New Bond Street, Worcester, Massachusetts, U.S.A.) June 20, 1930, No. 18845. [Class 60.] Gauges; driving and feed devices.- Consists of a calipering-device for a grinding. machine which, when the work is nearly to size opens an electric circuit of a low-voltage relay, whereby a solenoid in a high voltage circuit operates to stop the feed, and when the work is exactly to size opens another circuit to cause a reversal of the feeding movement. The device is described as applied to a machine for grinding a cylindrical work-piece 10, and comprises a grinding-wheel 12 on a slide 16 which is fed towards and moved from the work bv a screw 20. The screw carries a toothed wheel 24 adapted to be driven, for giving the feed motion, from a toothed wheel 40 on a driven spindle 42 through a wheel 44, which is carried by a lever 46 pivoted on the spindle 42 and movable into and out of engagement with the wheel 24 by a lever 50. The screw also carries a toothed wheel 62 driven to give reverse movement to the grinding-wheel slide 16, from the spindle 42 by a train of gears 54, 56, 60 and a gear 64 movable by a lever 68, pivoted on the screw, into and out of gear with the wheel 60; the withdrawal of the grinding-wheel by means of this gearing takes place at higher speed than the feed. The calipering-device comprises a casing 76 carried by a guard 74 for the wheel 12, and within the casing is pivoted on knife edges on bellcrank lever 100, 102, the arm 100 carrying a graduated micrometer screw 90 engaging a feeler rod 78 carried by the casing 76 and having a diamond point resting on the work ; a frame 82 also is mounted on the casing and carries adjustable positioning screws 84, 86. The lever is held on its knife edges by a spring plug 120 and the arm 100 is pressed down by a spring 130. The arm 100 makes electrical contact with an adjustable spring contact 140 until the work is nearly to size, and the arm 102 makes contact with an adjustablecontact 142 until the work is exactly to size; opening of the contacts 100, 140 de-energizes a relay 170 operated from a low-voltage battery 160, and allows this to close a circuit from high voltage lines 182, 184 to a solenoid 176, which actuates the lever 50 to move the wheel 44 from engagement. with the wheel 24 and so to stop the feeding movement of the wheel 12, finish grinding then taking place by the spring of the parts. When the work is exactly to size the contacts 102, 142 are opened and a solenoid 190 is similarly energized through a relay 168 to throw the wheel 64 into gear to start the withdrawal of the grinding-wheel. When the wheel is withdrawn sufficiently, the movement is stopped by the closing of a switch 210, which re-energizes the relay and consequently de-energizes. the solenoid 190. The switch 210 is closed by a cam 218 on a hand-wheel 30 carried by the shaft 28 of the gear wheel 26; the cam has also a second part adapted to open the switch 210 when the grinding-wheel is returned towards the grinding position.