GB700956A - A method of and apparatus for forging crankshafts - Google Patents

Abstract

700,956. Forging crankshafts. ERIE FORGE CO. Nov. 23, 1951 [Dec. 7, 1950], No. 27514/51. Class 83 (4) A method of forging a crank shaft from a billet having portions to form a crank pin and journals comprises offsetting the pin portion of the billet while moving the journal portions of the billet endwise towards each other along the axis of the shaft the movements being related such that the neutral axes of the web portions are substantially neither stretched nor compressed. The crank shaft is formed from a billet 4 having a neutral axis 5 by dies arranged as shown in Fig. 8. The lower halves 11 of the journal forming dies are slidably carried on guides 12 on a bed 13 and the upper halves 14 are slidably carried on a cross head 15 which is moved downward by a piston 16. The die halves 14 are vertically slidable in guides 17 which are moved horizontally towards each other by rams 18. The cross-head 15 carries the upper half 19 of a crank-pin forming die the lower half 20 being. carried by a piston 21 in the bed 13. The billet 4 is initially supported by the lower halves 11 and 20 of the journal and pin dies. After the journal dies 11 and 14 are closed the piston 21 moves the lower pin die 20 upwards until it mates with the upper pin die 19, thereby forging the crank pin. Simultaneously with the upward movement of the piston 21 the rams 18 slide the journal dies 11 and 14 horizontally towards each other all the movements being so related that the web forming portions of the billet are neither stretched nor compressed. After the crank-pin has been forged the rams 18 complete the forging of the webs by moving the dies 11 and 14 until they abut against the pin dies 19 and 20. The pin and journal dies have recesses 24 and 25 for forming the lower inside surface of the webs and upper outside surface respectively. The neutral axis of the finished web is normal to the axis of the crank shaft and joins the neutral axes of the journals-and crank pins by fillets 9 and 10 respectively. The relative travel of the journal and pin dies is controlled by a cam 27 on one of the journal dies and a cam follower 29 of a switch 28 carried by the lower pin die 20. As the switch moves upwards with the die 20 the cam follower drops and starts the movement of the journal dies towards each other. This endwise movement stops when the cam 27 moves inward sufficiently to return the switch to the position shown in Fig. 8. During the forging of the webs the cam follower 29 rides on the flat surface 27a of the cam 27. The dies may also be controlled manually. In an embodiment each of the horizontal presses has eight cylinders 30. Fig. 14, four at each end arranged vertically so that two act on each half of the journal dies. The cylinders 30 are bored in a pair of frames 31 arranged on top of one another and the reaction force of each pair is taken by strain rods 32 and compression rods 33 connected to the outer end of the frames. The ends of the top and bottom frames are connected by distance rods 34. The pressure from the rams 18 is transferred to the guides 17 by a pintle 35, Fig. 16, having ball and socket joints 36, 37 with the ram and guide respectively. The guides 17 are made in two parts hinged at the centre 38 so that they assume a pressure equalizing position on the journal dies 11, 14 and the rams 18 also have a pressure equalizing connection with the guides.