GB717356A - Improvements relating to the measurement of electrode current and pressure in electric spot welding - Google Patents

Abstract

717,356. Dynamometers. NATIONAL RESEARCH DEVELOPMENT CORPORATION. April 8, 1953 [April 8, 1952], No. 8970/52. Class 106 (2). [Also in Groups XXII and XXXVI] In apparatus for measuring and recording the welding current and electrode pressure of a spot or projection welding machine, a copper-chromium tube 1 is formed at its upper end with a shouldered female taper accommodating a welding electrode 4 and its lower end with a dished flange: 24 clamped by screws 26 through its rim 28 to a similar dished flange 25 provided with a male taper 2 for connection to the electrode adapter of a welding machine. The space between the flanges is sealed from the inner bore of the tube (through which a coolant may be circulated) by a rubber ring 29 and is connected by a tube 30 with a non-magnetic Bourdon tube 31 encircling the conducting tube 1 and carrying a pointer 33 bearing on a waxed paper recording strip 20 traversed by a motor-driven drum 21 during welding. A rectangular moving coil 5 is suspended by phosphor bronze strips 6, 7 between insulated clamps 8, 9 mounted on the tube 1 for vibration about an axis parallel to that of the tube at a natural frequency of at least 100 c.p.s. and is energized through a terminal block 16 with a constant direct current in series with an electromagnet coil 13, whose polepieces 12 enbrace a damping vane 10 carried by the moving coil. The coil 5 carries a pointer 18 bearing on the waxed paper strip, on which traces are recorded to represent the variations of the pressure imposed on the welding electrodes and of the fluctuations of current in the weld, the damping characteristics of the coil system being such as to follow accurately the individual cycles of we!ding current if the latter is alternating.