GB1468113A - Production of comutators for rotary electrical machines - Google Patents

Abstract

1468113 Making commutators; forging; extruding KABELUND METALLWERKE GUTEHOFFNUNGSHUTTE AG 27 Aug 1975 [27 Sept 1974] 35362/75 Headings B3A B3H and B3P A commutator is provided by extruding a cup with inwardly projecting ribs from a copper or copper alloy blank, punching out the starshaped portion of the bottom which is defined by the ribs, reducing the outside diameter of the product by extrusion while reducing the spacing between the ribs, filling the recesses between the ribs with insulating material, and externally machining the result until the insulating material is exposed. Apparatus for carrying out the first three stages includes a single press having ribbed rams or punches and manual or automatic transfer of the blanks between the stages. Fig. 1a shows on the left a blank 1 located in die 4 having an ejector 5. On the right, ram 6 having ridges 7 is shown at the end of its stroke having formed a cup 2 having recesses 8 between ribs 3. The bottom of the cup is then punched out by a punch having ridges like those of ram 6, so that the ribs 3 are not reformed. The product 12, Fig. 3a is then extruded through die 13 having reduced portion 15, by tool 14 having ridges 7 of less thickness than those of the ram and punch of preceding stages. At the same time, projections 16 on the die form flutes 17, and the internal diameter is enlarged slightly, whereby the rib formations of Fig. 3c result. A plurality of the resulting tubes are then mounted on a shaft, the recesses filled with insulating material, and the tubes are externally machined to expose the material. The shaft may then be removed, or divided to provide a shaft for each commutator.