Patent GB-1259406-A (GB)
IPC: H01F7/20
Filed: 1970-06-11
Abstract: 1,259,406. Lifting electromagnets. NISHISHIBA ELECTRIC CO. Ltd. 11 June, 1970, No. 28267/70. Heading H1P. A lifting magnet 20 (Figs. 2, 3) for elongate magnetizable loads is suspended from a traveling crane (Fig. 1, not shown) and energized from a stabilized D.C. source over switching and a drop cable; and comprises a steel yoke frame 21 formed with dependent integral poles 22, 23 wound with main exciting coils. Elongate pole members 25, 26 assembled of welded parallel steel blocks 27, 28, 29; 30, 31, 32 have greater height and length in the inner blocks than in the outer and are widths equal to the diameters of poles 22, 23. The central blocks are slotted along the edges and ends to receive preformed auxiliary windings wedged in (Fig. 4, not shown) and the pole members are rotatably mounted in the frame 21 on tubular steel spindle 39 bolted through the three blocks which extends through pole 22 (or 23) of the frame member 21 into opening 44 of thrust collar 45 radially butted on; a seat 48 welded to frame 12 bearing the weight of the assembly 25. Arm 49 diametrically bolted to collar 45 is linked by the rods 55, 56 to a similar arm bolted to collar 54 of pole member 26 to form a parallel linkage for synchronous rotation of the members in either sense relatively to the frame by an electrohydraulic activator 57 controlled from the crane cabin or a pendant switch. Main and auxiliary coils 24, 124; 36, 136 are excited (Fig. 5) from the D.C. source respectively over normally open series switches 73, 74 shunted by normally open switch 77, and directly. To lift plural loads (Figs. 6a, 6b, not shown) pole members 25, 26 are parallelly positioned normal to the frame and switch 77 is closed to energize all coils, while to lift only one load the members 25, 26 are rotated into alignment with the frame, and the magnet is lowered to contact the selected load. Switch 73 is closed automatically on hoist and switch 74 is closed by relay 75 after a preset interval. Thus coils 36, 136 are initially energized to select and lift clear the required load, after which coils 24, 124 are energized to reinforce the lift after clearance, without attracting adjoining loads, since the side blocks have clearance from the load surface. The pole members may be rotated to intermediate angular positions to select a desired number of adjacent loads.  In a modification (Fig. 7, not shown) the pole members each have single coils and are individually rotated by worm and sector motors, In a further modification (Fig. 8, not shown) the pole members are welded to steel supporting standards and have machined end slots to receive the ends of preformed coils; the sides of which are wedged into position, in slots defined by steel side parts welded or bolted to the central part. In a further modification (Figs. 9, 10, not shown), the pole members are integrally formed with cylindrical supporting standards extending through openings in the frame, having bolted collars which beam on supporting thrust races; the members being rotatable by worm and sector motors. The members have three pairs of square coils wedged in position in slots, and energized in opposite magnetic polarities.