Abstract: A method of production of an electric contact including a contact base member of one metal and a contact member of another metal of hardness lower than that of the contact base member joined to the contact member at one end portion thereof, with the method comprising the steps of forming a blind hole at the one end portion of the contact base member and applying pressure simultaneously to the contact base member and the contact member after the contact member is inserted and filled in the blind hole, to thereby cause the metals of the two members undergo plastic deformation to join them together in intimate contact with each other.

Abstract: A plurality of permanent magnets (4) are disposed with gaps between adjacent magnets along the inner peripheral surface of a yoke (2) of a stator for a magneto D.C. motor. In gaps between magnets, there are provided retainers (3), ech of which is made of an elastic member and consists of one surface (11) fixed on the yoke, two surfaces (12, 13) extending in the central axial direction of the D.C. motor along the side facing surfaces (71, 72) of the magnets opposite to each other on the inner peripheral surface of the yoke and two end portions (32) connecting these two surfaces (12, 13). Those two surfaces (12, 13) and end portions (32) are kept in contact with the permanent magnet from three directions, namely from both facing surfaces (71, 72) of the permanent magnet and from each of the outer surfaces (81, 82) of the magnets adjacent to each facing surface (71, 72) extending in the central axial direction, whereby the permanent magnets are pressed and clamped so as to be secured to the yoke.

Abstract: In a permanent type DC motor, a stator comprises a yoke and a plurality of magnetic pole pairs composed of permanent magnets and auxiliary poles. The plurality of magnetic pole pairs are held and fixed in intimate contact with the yoke by pressingly deforming a cylindrical thin plate made of magnetic material such as a steel plate. The fixture of the magnetic pole pairs composed of the permanent magnets and auxiliary poles is attained by a projecting part formed by pressingly deforming a part of the thin cylindrical plate made of the magnetic material toward a space between the adjacent pole pairs and by using U-shaped magnetic retaining pieces.

Abstract: Two or more imbalance correcting openings with the same cross-sectional configuration are provided in an armature core in parallel to a shaft in such a manner as to be equally spaced on a circumference which is concentric with the shaft, and weights are inserted in the adjacent openings to thereby correct any imbalance, the number of adjacent openings being selected to be (N-1)/2+1 or less when the number n of openings is odd and to be n/2 or less when the number n is even.

Abstract: A method of production of a cylindrical body from a sheet of steel formed at opposite sides with projections and cutouts complementary to each other. The method comprises the steps of rolling the sheet of steel and inserting the projections in the cutouts to provide a cylindrical blank, and compressing at least one of inner and outer peripheral surfaces of the cylindrical blank in a radial direction to reduce the thickness of the cylindrical blank and to stretch a portion of the cylindrical blank in an axial direction whereby the projections inserted in the cutouts can be brought into intimate contact with each other at jointed portions.