GB569251A - Improvements in or relating to magnetic holding devices - Google Patents

Abstract

569,251. Permanent magnets. BELITSKY, J. June 4, 1943, Nos. 9017/43 and 12699/44. [Class :35] [Also in Groups XXIII and XXXVI] A magnetic holding device for holding the negative electrodes of an electric arc-welding system in contact with the part to be welded, comprises two magnets 1, 2 of permanent or electro-magnetic type and of horseshoe shape. spaced by blocks 3 of non-magnetic material, for example, brass, and bridged by a plate 4. The magnets are provided with polepieces 5, 6 the gap between the polepieces being filled in by a strip 7 of non-magnetic but electrically conducting material. for example, copper, and passing through the plate 4 and polepieces 5, 6 are electrodes 9, 10 insulated by brushes 11 or by tubes and connected to a bar 8 to which the negative lead 14 is clamped : a spring 16 .normally holds the electrodes in a position projecting beyond the face of the polepieces. Rotatably supported between the poles of the magnets is a. cylindrical member composed partly of non-magnetic material 17 and partly of magnetic material 18, the part 18 having radial projections 20 adapted, when the member is rotated by an arm to bring the part 18 between the polepieces and so partially to divert the magnetic flux to pass through slots 21 to contact the work and assist in removal of the holder. In a modification, the construction is generally similar to that described above, but a single electrode is employed resting on the centre part of the rotatable cylindrical member, through which and the non-magnetic strip between the polepieces, the current passes. In a further modification, Fig, 12, the magnet comprises a rectangular block 26 with polepieces 27, 28 carrying extensions 29, 30 between which is the rotatable member 31 ; the lower ends of the polepieces carry interchangeable sole pieces 34,35 secured by screws 37 and having faces shaped to fit the work. The negative lead 14 is connected to two electrodes 9, 10 slidable in insulating sleeves and pressed down by a spring 42 ; the electrodes may have removable and interchangeable lower ends, shaped to fit the work, or the electrodes may be removable and interchangeable. The holder parts are enclosed in a casing 46 and the member 31 may be rotatable by a knurled knob, or by an arm.