| 摘要 |
607,148. Magnets. NEILL & CO: (SHEFFIELD), Ltd., J., and EDWARDS, A. Jan. 28; 1946, No. 2662. [Class 35] [Also in Group XXV] A catch for doors or the like comprises a permanent magnet 10, Fig. 1, cast with a central gap 11 leaving on one side two polar faces 12, 13 spaced well apart, the gap being continued shallower into the adjacent side 14, and with two slots 18 for fixing the door to the frame, and a mild steel keeper 21, Fig. 3, secured at a point intermediate the pole faces to 'a leaf spring 23 attached to the frame or door 26. Alternatively, the magnet, or both magnet and keeper, may be resiliently mounted. A modification is described in which the magnet consists of a member of square cross-section secured between two mild steel polepieces of greater cross-section by a non-magnetic rivet, the polepieces having lugs for securing the magnet in position so that there are three remaining pairs of pole edges exposed, of which any pair may be used to attract the keeper. The keeper may be somewhat longer than the magnet to provide for irregularities. A magnetic alloy of the iron-nickel-aluminium type, with or without other elements such as copper cobalt and titanium should preferably be used, and may be cooled in a magnetic field to render it anisotropic. Instead of being cast, the magnet may be made by moulding, pressing and sintering powdered ingredients. |
