GB1302723A - - Google Patents

Abstract

1302723 Magnetic holding devices ULVSUNDA VERKSTADER AB 10 June 1970 [18 June 1969] 28119/70 Heading H1P A magnetic chuck comprises a sleeve of magnetisable material on a chuck tailstock 2 formed with annular groove 3 extending coaxially to accommodate annular coil 5, the groove being closed by annular magnetizable member 6 having a gap 24. A rotary spindle is ballbearing mounted in the tailstock to rotate driving sleeve 11 and affixed intermediate sleeve 8 in brass bearing 10 fitted in annular member 6. The sleeve 8 carries a magnetizable retaining ring 12 united over annular non magnetizable member 13 with magnetizable retaining ring 14 screwed to member 6. The rings 12, 14 have external annular flanges 15, 16 coaxial with the centre line and separated by non magnetic ring 17 to engage workpiece 19. On energization of the coil, magnetic flux traverses stationary part 1 and rotating part 8, 12, 14, 6 to retain the workpiece, and a magnetic field responsive device 20 in the field tranversing part 1 (Fig. 2); e.g. an adjustible sensitivity reed relay controlling the energization current for a desired work force. For demagnetization, D.C. is supplied to coil 5 in opposite force to the magnetizing current, and device 20 is associated with core 21 and winding 22 whose excitation is controlled by a potentiometer to produce a premagnetizing field opposed to that of the demagnetizing current so that the resultant field is zero when the chuck is zero, and the relay controls cut-off of the demagnetizing current.