GB595416A - Improvements in electro-mechanical control mechanism for lathes and like machine tools - Google Patents

Abstract

595,416. Driving machines ; turning. CARVER, T. A. B. Jan. 11, 1945, No. 902. [Class 83 (iii)] [Also in Group XXIII] A lathe, grinding- machine, or like machine tool having electro-mechanical control means for disengaging the feed motions and means by which the rate of feed is reduced prior to the disengagement, is characterized in that a switch, Fig. 6, attached either to the saddle or the bed, closes the circuit to electrical feed controlling and shifting mechanism when the tool reaches the end of a cutting operation, the switch consisting of a pair of contact points a, alpha<1>. urged into contact with one another by a light spring # and controlled by the movement of a long pivoted lever having a stronger spring # acting oppositely to the other spring ; the short arm of the lever carries a hardened piece #, pressure on which closes the switch ; a second pair of contact points p, p<1> being in circuit with the means for controlling the change from fast to slow speed drive arranged similarly to the other contact points, and utilizing the same lever arm, but adjusted to come into operation earlier than these. Pressure on the piece e is provided by a rod # secured to a micrometer Á clamped to a bracket provided on the bed or saddle of the machine according to which of these members the switch is secured. Closing of the contacts p, p<1> operates an electromagnet P, Fig. 7, which releases a trip N from a spring- controlled lever K. This lever is linked to a further lever L, connected to a pivoted arm C, which carries on the shaft T a wheel B -of the feed train. The lever movement disengages the wheel B from the normal feed drive wheel F and throws it into engagement with a very fine ratchet-feed wheel H. With fine feed now engaged, after a small further movement of a saddle or cross slide, the contacts alpha, alpha<1> of the switch are closed and an electro-mechanical relay is set in motion, Fig. 1, the shaft J of which carries an arm and a chain which rolls on the sleeve J<1 >to exert a pull on one or more flexible wire transmission members X. The pull may be transmitted to a disengaging device, Fig. 2, of a half nut, to stop the feed motion, or to a belt-shifter to stop the whole machine. These devices are fitted with cut-out switches V so that after operation the main circuit may still be ready to operate for any other feed movements. For setting up the switch operating stops visual or audible means may be included in the control circuits and also the circuits may be so arranged that the contact of tool and work stops the machine. Specification 345,325, [Group XXIV], which describes the electro-mechanical relay device, is referred to.