GB760137A - Process and apparatus for forging multi-throw crank-shafts - Google Patents

Abstract

760,137. Making crank-shafts. BOVERT, E. VOM. Jan. 15, 1954 [Jan. 27, 1953], No. 1203/54. Classes 83 (2) and 83 (4). Forging.-In the forging of multi-throw crankshafts from a preformed bar, Fig. 8, having enlargements 33 between forged-in journal portions 30, each crank throw is formed by an initial forging operation performed by a first tool 12 and die 4, Fig. 1, and the crank throw is then turned through a right-angle and is finish forged by a second tool 13 and die 15, Fig. 4. The forging apparatus, Fig. 1, comprises a base-plate 1 secured to the bolster 1b of a press and supporting adjustable saddles 2, 3, which carry press tools 2a, 3a. Vertically movable upper plates 5, 6, which may be strapped together to form a common unit, support saddles 8 which carry-press, tools 8a. The plates 5, 6 are mounted on push-rods 9, guided in heat insulated supports 20, Fig. 4, which are operated by hydraulic rams disposed below the press bolster. A substantially cylindrical blank which may have been machined on a lathe is heated to forging temperature and is then supported on the tools 2a, 2b and the upper plates are lowered thereby causing the press tools to form the spaced journal portions 30, Fig. 8. The tools 2a, 3a, 8a are then replaced by tools which form the neck portions to cylindrical shape and after this operation these tools remain in their closed position to support the workpiece whilst the vertically moving tool 12, actuated by the main press ram 10, co-operates with the fixed dieplate 4 to effect the initial forging of the crank throw 34. The other crank throws are then initially forged at their correct relative angular spacings which are set by a template. This operation forms the workpiece of Figs. 10, 11 (not shown). The tool 12 and die 4 are then replaced by the second tool 13, and die 15, Fig. 4, with an interposed die wedge 14. The workpiece after being reheated is supported in the saddles with a preforged crank throw 34 lying in a horizontal plane and the tool 13 and die 14 are closed. This causes the wedge 14 to move to the right and press against the crank-pin portion 35 whilst the tool and die form the crank webs to elliptical form 37. Counterweights may be formed on the crank webs during the final forging operation. The heating of the workpiece is sufficient for all of the crank throws of a crank-shaft to be forged. To enable batch. production a number of workpieces are subjected to the initial forging before the tools are changed for the final forging. The forged crank-shaft may subsequently be machined throughout or only the crank pins and journals will be machined. Large crank-shafts may be made in two parts connected together'by bolts