Abstract: In a method of manufacturing a partly flat yoke having curved circumferential walls to which magnets are to be attached and having parallel flat circumferential walls which constitute main magnetic paths and whose each radial thickness is larger than that of the curved circumferential walls, by drawing a sheet of metal plate, the metal plate is held down between a die and projections of a wrinkle preventing plate provided at given angular positions around an outer circumference of a cavity of the die so as to correspond to the curved circumferential walls. Then, a punch presses down the metal plate into the cavity so that material of the metal plate extends axially into the cavity, while the material of the metal plate flows circumferentially from each side of the curved circumferential walls to sides of the parallel flat circumferential walls.

Abstract: A method of manufacturing a commutator includes the steps of punching a commutator forming plate out of a plate member having a plurality of projections formed at predetermined intervals in such a way that the projections extend in parallel to one another, forming the commutator forming plate cylindrical and arranging the projections on an inner surface of the cylindrical commutator forming plate, filling an interior of the cylindrical commutator forming plate with a molten resin, segmenting the cylindrical commutator forming plate at predetermined angular distances after curing of the resin to thereby form commutator pieces, and positioning the plate member in a mold. The step of punching the commutator forming plate is carried out using a first punch having a plurality of recesses corresponding to the projections. Formed at those portions of each recess which correspond to both corner portions of each projection narrow portions that become narrower in a depth direction of that recess.

Abstract: In a commutator forming plate to be rounded into a cylinder which is to be cut at constant angular intervals to form a plurality of commutator segments after being filled with insulating material, a plurality of lands rising at given intervals on one surface of a plate is provided and a plurality of projecting portions protruding nearly perpendicular to a rising direction of each of the lands are formed simultaneously by forming a plurality of grooves crossing with each other on the respective lands and extending so as to intersect obliquely with respective outer peripheries of the lands.

Abstract: A cup shaped yoke made of sheet material has an opening portion provided in a side wall on an axial end side, a shoulder portion provided in the sidewall on another axial end side, a magnet installation portion for installing a magnet, which is provided in the side wall between the opening and shoulder portions and whose wall thickness is substantially equal to thickness of the sheet material, and a bottom portion, which is provided in a bottom wall, having a boss shaped bearing accommodating portion in a center thereof. Each wall thickness of the opening, shoulder and bottom portions including the boss shaped bearing accommodating portion is equal to or smaller than a half of wall thickness of the magnet installation portion.

Abstract: A plate material is drawn to form a first-drawing product in the shape of an elliptically cylindrical container having an elliptical cross section. Then, the first-drawing product is drawn to form a re-drawing product in the shape of a generally circular cylindrical container. Next, the re-drawing product is drawn to form a late-drawing product in the shape of an elliptically cylindrical container having an elliptical cross section in which a major axis and a minor axis of the elliptical cross section are reversed with respect to a major axis and a minor axis of the elliptical cross section of the first-drawing product. Thereafter, the late-drawing product is drawn to form a final product as a yoke.

Abstract: In a method of manufacturing a partly flat yoke having curved circumferential walls to which magnets are to be attached and having parallel flat circumferential walls which constitute main magnetic paths and whose each radial thickness is larger than that of the curved circumferential walls, by drawing a sheet of metal plate, the metal plate is held down between a die and projections of a wrinkle preventing plate provided at given angular positions around an outer circumference of a cavity of the die so as to correspond to the curved circumferential walls. Then, a punch presses down the metal plate into the cavity so that material of the metal plate extends axially into the cavity, while the material of the metal plate flows circumferentially from each side of the curved circumferential walls to sides of the parallel flat circumferential walls.

Abstract: In a commutator forming plate to be rounded into a cylinder which is to be cut at constant angular intervals to form a plurality of commutator segments after being filled with insulating material, a plurality of lands rising at given intervals on one surface of a plate is provided and a plurality of projecting portions protruding nearly perpendicular to a rising direction of each of the lands are formed simultaneously by forming a plurality of grooves crossing with each other on the respective lands and extending so as to intersect obliquely with respective outer peripheries of the lands.

Abstract: A crude work having a cylindrical boss formed integrally with a base plate is processed to a final product by a press work without using additional machining. An inner diameter of the boss is enlarged by a punch, and at the same time an outer diameter of the boss is shrunk by an outer die, while the work is supported on a cushion ring to which a force against the movement of the punch and the outer die is applied. Some of the material constituting the cylindrical boss is squeezed, and a bulge is formed at a foot of the cylindrical boss out of the material squeezed. Since the bulge is fromed in a confined space in the die structure, no crack or defect develops in or on the bulge. The bulge is further compressed by a press work to form a flat flange out of the bulge. The cylindrical boss having the flange formed integrally therewith is used as a center boss for holding a bearing of a rotary machine.

Abstract: A method of adhering in advance a soldering material to a location on each of a plurality of claw-shaped portions of a commutator at which a winding for the armature of an electric motor is to be electrically connected thereto, for ensuring a strong and reliable electrical connection between the windings and the claw-shaped portions.A plurality of narrow grooves are defined in the claw-shaped portions and the narrow grooves are charged with molten soldering material, which solidifies therein. The thus-solidified soldering material is thereafter re-melted by heat produced at the time of resistance welding of the windings to the claw-shaped portions to thereby reinforce the electrical connection between the claw-shaped portions and the windings and to prevent an increase in the electric resistance between the windings and the claw-shaped portions.

Abstract: A link rod of a wiper for a motor vehicle, comprising: a cylindrical section; a pair of flat sections formed at opposite ends of the cylindrical section, respectively by crushing the opposite ends of the cylindrical section from above and below; and a pair of resinous coupling joints mounted on the flat sections, respectively; wherein a first hole having a large diameter and a second hole having a small diameter are, respectively, formed at outer and inner portions of each of the flat sections as viewed in a longitudinal direction of the cylindrical section; wherein a gap opens into an axially intermediate portion of a peripheral surface of the second hole such that interior of the cylindrical section is communicated with a mouth of the second hole through the gap; wherein each of the coupling joints includes a joint portion disposed at the first hole and seals the second hole and the gap, and a method of manufacturing the link rod.

Abstract: A method of manufacturing a laminated core for a dynamo-electric machine, having a shaft and a plurality of core sheets with through holes in the center thereof for inserting the shaft therethrough and a plurality of slot holes in the peripheral portion thereof. In the same method, there is provided a construction in which the core sheet is punched so that at least a part of scrap sections to be punched and then removed, including the through hole and the slot holes, is formed as a half die-cut portion, the half die-cut portion formed on the core sheet being fitted to another adjacent core sheet. After the plurality of core sheets are laminated together, the shaft is forced through the through holes and at the same time the half die-cut portions are removed. Therefore, an integration of core sheets is obtained after die-cutting, thereby resulting in easier handling.

Abstract: A link rod of a wiper for a motor vehicle, comprising: a cylindrical section; a pair of flat sections formed at opposite ends of the cylindrical section, respectively by crushing the opposite ends of the cylindrical section from above and below; and a pair of resinous coupling joints mounted on the flat sections, respectively; wherein a first hole having a large diameter and a second hole having a small diameter are, respectively, formed at outer and inner portions of each of the flat sections as viewed in a longitudinal direction of the cylindrical section; wherein a gap opens into an axially intermediate portion of a peripheral surface of the second hole such that interior of the cylindrical section is communicated with a mouth of the second hole through the gap; wherein each of the coupling joints includes a joint portion disposed at the first hole and seals the second hole and the gap, and a method of manufacturing the link rod.

Abstract: Four side walls surrounding a recess in the center of a commutator segment are extended to overhang toward the recess comprising claws and cut-and-raised protrusions, thereby ensuring that the commutator segment is securely engaged with the resin filled in the recess against any of the triaxial stresses due to centrifugal force, rotating force, and tensile force. The volume of cutting in the insulating resin at undercut portions is reduced. The internal and cut-and-raised protrusions are molded by cylindrically bending oriented progressive dies made of plate material.