GB831236A - Improvements in method of making laminated frames - Google Patents

Abstract

831,236. Making magnetic cores; angular bending. GENERAL ELECTRIC CO. July 30, 1957 [Aug. 1, 1956], No. 24133/57. Classes 83 (2) and 83 (4). [Also in Group XXXV] A method of forming a laminated core is characterized by the steps of assembling flat strips of electrically conductive material into a stack, securing the strips of material into a rigid assembly to prevent movement of the strips relative to each other, and rolling the assembly edgewise of the strips into the form of an arc of a circle. Laminations 10, coated with magnesium oxide to prevent fusing, are stacked on an end plate 12 to which a sacrifice plate 16 has been welded perpendicular thereto. An end plate 14 is then placed on the laminations 10 and a plurality of jacks spaced along the assembly are actuated to compress the laminations and end plates. Grooves 24 are chipped in the vertical side of the stack and are filled with weld material to prevent relative movement of the laminations 10. After the welds have been ground flush a wrapper plate 18 is placed against the exposed edges of the laminations 10 and jack welded to the end plates 12, 14. Complete welds are then made at the junction of the plates and the jacks are removed. The assembly is then annealed in an oven whose temperature rises for three hours until it reaches 1150‹ C. when the assembly is removed and immediately rolled into semi-circular form. The ends of this assembly and another similarly formed are machined smooth and the two assemblies are welded together to form a cylindrical core for a direct-current motor. The plate 16 is then machined off or the plates 12, 14 are faced to remove a weld 22 and part of a weld 20 so that the plate 16 may be removed without machining. The bent halves may be annealed prior to being connected into an integral unit. Instead of the plates 16, 18, bolts 40, Fig. 6, and if necessary end plates 12, 14 may be used to hold the laminations 10 together. The assembly may be cold rolled. The application of pressure prior to rolling may be elminated. The assembly may be rolled to form a non-semi-circular arc. The plate 18 may be of a thickness greater than or equal to the width of the laminations 10. The assembly may be rolled to form a circle, the ends of which are then smoothed, pushed towards one another and welded or bolted together to complete the frame which may be annealed before extracting the plate 16.