GB132543A - - Google Patents

Abstract

132,543. Arter, W. Sept. 10, 1917. Electro-magnetic chucks. - An electro - magnetic chuck is provided with a work-holding face consisting of a series of polar arms or bars radiating from a centre, and a second series of polar arms or bars extending inwards from the perimeter and alternating with the arms or bars of the first series, the arms or bars of each series being formed with lateral projections on one or both sides, with the projections of the arms of one series lying between the projections of the adjacent arms of the other series, and the two series being separated by non-magnetic material. The projections may be concentric, and those on one side of an arm may be staggered relatively to those on the other side. As shown in Figs. 1 and 2, the first series of polar arms 3, with staggered and concentric projections 8, is integral with a core 2 surrounded by a coil 11, the second series 5 being integral with an annular pole-piece 4 surrounding the coil. The core and outer pole-piece are connected by a base 6 of magnetizable material, a plate 15 of non-magnetic material being interposed between the base and a support 12 upon the machine, and current being conducted to the coil by brushes bearing upon slip-rings 17, 18 on an insulating-ring 19. The chuck face may, however, be in the form of an element or plate separate from the core and pole-piece, but adapted to be secured thereto. The chuck may also be provided with an auxiliary face-plate having arms and projections corresponding to the arms and projections of the chuck face, and, when the plate is smaller than the working face of the chuck, non-magnetic material is provided in the plate at' the points where otherwise it would magnetically connect the two series of polar arms of the chuck face. In the construction shown in Fig. 9, the polar arms or bars 38 of the first series are independent of each other and are provided with individual magnetizing-coils and cores 39, a central core and magnetizing-coil 37 being associated with the second series of arms or bars 36, which extend inwards from an outer shell 35. Or the central core may carry a third series of arms, which alternate with the inner ends of the second series of arms and are in line with, but magnetically separated from, the arms of the first series. The chuck may also consist of a circular chuck element closely surrounded by a second chuck element of annular form. This second element comprises an annular pole-piece with spaced radial arms or bars, and a series of cores and coils which are arranged within the pole-piece and provided with other spaced radial arms or bars extending into the spaces between the first arms or bars.