GB651922A - Improvements in and relating to cutter mechanisms - Google Patents

Abstract

651,922. Grinding grooves in welding electrodes and the like. METROPOLITANVICKERS ELECTRICAL CO., Ltd. July 9, 1948, No. 18541. Convention date. July 25, 1947. [Class 60] [Also in Group XXII] A cutter mechanism for producing a predetermined depth of cut in continuously fed strip or rod like material comprises an adjustably mounted cutter and a guide for positioning the material relative to the cutter, a device for gauging the depth of cut which engages an unsupported portion of the material and is freely movable therewith at right-angles to the direction of the feed, and means controlled by the gauging device for re-establishing an initial adjustment of the cutter relative to the guide when a predetermined decrease in the depth of cut has occurred. The cutter may be used with the welding machine described in Specification 548,820, [Group XXII], to cut a groove 67 in the electrode 3 prior to the engagement of the latter with the contact mechanism for supplying the welding current. The cutter 45, which takes the form of a thin disc-type grinding wheel of, say, eight inches diameter rotating at about 3,400 r.p.m., is driven by a motor 12 secured to a slide 16 which is traversed by a screw 23 actuated by a pawl 26 and a ratchet wheel 25 in a slideway provided with a transversely adjustable guide bar so that play may be taken up. The rod 3 may be fed in the normal way by the welding head and is guided by a grooved roller 52 and two bevelled rollers 53. The latter are journalled in a slide 54 which also supports the roller 52 and are biassed away from the cutter by a spring- loaded member 57 provided with balltipped bearing members 58 to bear on the central portions of the rollers. The guide for the slide 54 is secured to an adjustable platform 49 which freely supports by means of four links 69 a member 68 carrying the gauging device. The latter comprises a guide roller 78. journalled in a slide 79 and a calipering roll 70 journalled in a lever 72 pivoted on a pin supported by lugs 77 secured to the member 68. This lever, which is electrically insulated from the calipering roll, is spring-loaded towards the guide roller 78 and carries a stop 90 in contact with a second lever 88 also pivoted between the lugs 77. This second lever is also spring-loaded so that it presses on the plunger of a micro switch 94 controlling the circuit of an electromagnet 42. A plunger under the influence of the magnet is connected to one arm of a spring-loaded lever 27 which carries the pawl 26 and is pivoted about a support for the lead screw 23. As the peripheral face of the grinding wheel wears, the depth of the groove 67 is decreased and the calipering roller 70 consequently displaced away from the roller 78 to deflect the lever 72 and its stop 90 so that the second lever 89 may be displaced by its loading springs to close the switch 94. The resulting energization of the magnet 42 deflects the lever 27 to displace the slide 16 and restore the cut to its original depth. A stop 92 prevents excessive deflection of the lever 89. The spindle of the pawl 26 has two flats which are alternately engaged by a spring 28 to hold the pawl in either an operative or inoperative position, and the tension of the spring 28 is adjusted by a screw 31 which bears on a block 29 pivoted at 30. The slides 54 and 79 are adjusted by screw and nut mechanism, the screw 87 of which, in each case, Fig. 6, is bored and tapped to receive a screw 85. The latter bears on a pin 86 carried by a sleeve 84. When the screw 85 is tightened, a flange carried by the slide is gripped between a collar on the screw 87 and the sleeve 84. The ratchet wheel 25 is attached to the screw 23 in a similar fashion. The entire mechanism is enclosed in a casing provided with an inspection window and allowing access to parts requiring adjustment. A hood over the grinding disc extracts dust from the casing.