| 摘要 |
863,272. Magnets; electromagnets; magnetizing apparatus. FAIREY CO. Ltd. Oct. 14, 1958 [Oct. 18, 1957; Feb. 13, 1958], Nos. 32652/57 and 4775/58. Class 35. [Also in Group XXXVI] To ensure that the pole faces of a magnet assembly, e.g. in a nuclear magnetic resonance detector (see Group XXXVI), are accurately parallel, one of them is freely movable relative to the other and they are spaced apart by non- magnetic slip-gauges. The assembly comprises two sets of stacked rings 15, permanently magnetized in situ by coils 18, and connected by yokes 11, 12 to the polepieces, one of which, 20, is fixed while the other, 30, is a sliding fit in yoke 11. The polepiece 30 has a movable portion 32 connected to the remainder at a spherical seating 33, whose centre of curvature is near the middle of the air gap. The polepieces have lapped faces, either flat or curved; in the latter case the arcs are concentric, one convex, the other concave. The faces are spaced apart by one or more identical non-magnetic slips 40 of glass, quartz or bronze. If one slip only is used it is of horeseshoe shape, or annular with radial holes for the insertion of probes. Coils 48 on each polepiece enable the field strength to be varied. In alternative arrangements electromagnets may replace the permanent ones, and one polepiece may be connected to its yoke at a spherical surface while the other is slidable to set the gap length. According to the second Provisional Specification the movable polepiece is located in the yoke by two sets of balls in recesses in the yoke, each ball being adjusted radially with respect to the polepiece by a screw. In the first Provisional Specification flexibility of one polepiece is obtained by mounting it in a rubber or iron-loaded grease bush instead of employing the spherical seating arrangement previously described. |
