GB463995A - Improvements in and relating to abrading machines - Google Patents

Abstract

463,995. Abrading-machines. TRIGGS, W. W. (Norton Co.) Jan. 6, 1936, No. 428. [Class 60] In an abrading-machine comprising one or more discs having flat abrading or lapping surfaces, a work carriage, and means for causing an approaching movement between the discs and the work, the abrasion of the work to a predetermined extent causes the completion of the circuit to a relay which after a predetermined time stops the abrading action. In the apparatus shown a number of work-pieces 40 mounted in a cage 41 are rotated and revolved by the mechanism described in Specification 254,919, [Class 60], between a lower abrading disc 11 rotating in the base 10 and an upper abrading disc 14 rotating in a slide 16 which is movable vertically on an extension 13 of the base 10. The discs 11, 14 are rotated in opposite directions by an electric motor 50 through a clutch 56 controlled by a hand lever 57. The slide 16 is operable by a shaft 25 through worm gearing 23, 24 and rack and pinion gearing 20, 21. The shaft 25 may be rotated either by a hand wheel 30 or through a centrifugal clutch 37 by a reversible electric motor 32 controlled by a switch 38. Movement of the switch lever 39 to the position 39b causes the disc 14 to be lowered into contact with the work, when an adjustable stop 80 engages a lever 75 and restores the lever 39 to the neutral position. The slide is then lowered by turning the hand wheel 30, the worm 24 which is mounted between springs 26, 27 moving axially on the shaft 25 to give the desired pressure which is indicated on a dial 85. When the abrading action has proceeded to a predetermined extent a plunger 91 on the slide engages a fixed stop 95 and operates a lever 113 to separate contacts 115, 116 in the circuit of an electromagnet 140. A member 141 is thereby released to complete the circuit to a relay 142 which after a predetermined time energizes a solenoid 143 and thereby closes the circuits of solenoids 144, 145. The solenoid 144 operates to move the switch lever 39 to its upper position 39a causing the slide 16 to move upwards until a stop 81 swings the lever into its neutral position and the solenoid 145 operates the lever 57 to disengage the clutch 56. The circuit of the electromagnet 140 is supplied with low tension direct current from a transformer 126 through a rectifier 127. The transformer circuit is controlled by a mercury switch 130 which is opened by an adjustable stop 134 on the slide 16 as the slide moves upwards. The plunger 91 is mounted in an adjustable sleeve 100 carrying a dial indicator 90 operated by the plunger. Specifications 338,317, [Class 60], 363,695, and 421,568, also are referred to.