Patent GB-677366-A (GB)
Title: Improvements in or relating to the construction of commutators
IPC: H01R43/06
Filed: 1950-04-25
Abstract: 677,366. Making commutators; turning. NIPPERT, P. W. April 25, 1950, No.10150/50. Classes 83 (ii) and 83 (iii). [Also in Group XXIIT] A method of making commutators for dynamo electric machines comprises assembling a plurality of elongated segment forming bars with intervening strips of insulation into tubular sheaf form, reducing the diameter of one end of the sheaf and applying a retaining ring and then transversely cutting the reduced part of the sheaf from the body portion thereof to form a commutator annulus. Bars 8 (Fig. 22) of V-shaped cross-section are assembled with intervening insulation strips 9 around a tubular core 12<SP>1</SP> (Fig. 2), to form a sheaf which is pressed into a work tube 13<SP>1</SP> and the core 12<SP>1</SP> removed. The sheaf and work tube are placed in a magazine 17 of a machine comprising a frame 10 having end members 11 and 12 supporting triangularly spaced crossbars 13 carrying a casting 15 which supports the magazine 17 in a pair of roller bearings 16. The magazine is rotatable by a pulley 18 mounted thereon and connected by a driving belt 29 to an electric motor 27. A spacer tube 23 in the magazine ensures exact positioning of the work tube. The forward end of the magazine has a tapered bore 26. A ram 35 working in a double acting two-stage hydraulic cylinder 33 forces the sheaf through the tapered bore 26. An hydraulic pump 37 driven by electric motor 38 supplies pressure fluid to the ram. The cylinder 33 is hingedly mounted on the upper cross-bar 13 so that it can be swung aside to enable the sheaf to enter the rear of magazine. A second hydraulic cylinder 42, larger than cylinder 33, is secured to the end member 12 in spaced relation to the tapered bore 26 and houses a piston 46 mounted on a shaft 45 and carrying a shaft 44. The shaft 44 has an axial recess 47 to receive the shank 48 of a ring-receiving socket adapter 49 having a slotted recess 50 open at its upper end for receiving a work ring 51. Spring-loaded pawls retain the ring 51 in the adapter 49. The ram 35 and piston 46 are operated simultaneously by a lever 63 so that the piston 46 working in the larger cylinder holds the retaining ring firmly in line with the tapered bore 26 whilst the ram 35 extrudes a portion of the sheaf through the bore 26 and the ring 51. As the flow of fluid is reversed the adapter 49 is withdrawn and the ring is released so that it remains on the extruded portion of the sheaf. A check valve prevents the return of the ram 35 which remains ready for the next extruding operation. The position of the ring 51 is controlled by a spacer plate 55 and extension of the adapter which determines the length of the extruded portion of the sheaf is controlled by stop nuts 45a on shaft 45. After withdrawal of the adapter 49 the magazine is rotated by the motor 27 and a transversely movable cutting tool 57 (Fig. 10) carried on an arm 61 mounted on the upper cross-bar 13 is actuated by a two stage double-acting hydraulic ram 59 to sever the extruded portion of the sheaf which falls into a deposit slot 58. A lever 64 which controls the operation of the ram 59 for the cutting tool also actuates a switch 66 for energizing the electric motor 27 which rotates the magazine 17. A second switch 68 disposed in axial alignment with the shaft 45 ensures that the shaft is fully retracted prior to rotation of the magazine. In another embodiment a bed plate 110 carries upright members 111 and 112 which carry a cross-bar 113 (Fig. 15, 16). An hydraulic ram 135 horizontally disposed in a cylinder 133 is carried by members 111 and 172. A frame 174, including spaced uprights 175 and 176 and a yoke 178 is interposed between uprights 172 and 112. The uprights 175 and 176 are bored in axial alignment with the ram 135 to receive a work tube 185 formed with a flange 186 which abuts against a shoulder 182 of upright 176. The bore 197 of the work tube is tapered throughout its length. The work ring 51 is carried by end 149 of a spring-loaded ram 144 slidable in a sleeve 143 supported in the upright 112. Secured to the ram 144 is an operating lever 209 which may be moved along a slot 205 in the sleeve 143 to retract the ram or the ram may be locked in its forward position by moving the lever into a notch 206. The work ring 51 is held in the recess 50 in the end of the ram. After the sheaf has been.forced into the ring by the ram 135 the reduced portion is severed from the body of the sheaf by a circular saw 157 (see Group XXIII). Dove-tailed grooves are then machined in the end faces of the annulus and the grooves are sandblasted (see Group XXIII). A tubular core 124 (Fig. 23), having an inwardly dove-tailed end ring 126 and an outer insulating layer 125 is placed in the bore of the annulus. A free end ring 128 similar to the ring 126 is fitted into the other end of the core and flared outwardly as at 130 to lock the end rings in position. After flaring the work ring 51 is removed.