20th International Forgemasters Meeting - IFM 2017

a marine crankshaft is the key component for large ships’ power transmission. One of the critical techniques for the marine crankshaft manufacturing is the forging of its crankthrows. Existing forging techniques for marine crankthrows have limitations such as low material utilization, complex operations with multiple heatings, discontinuous material flowlines and cumbersome removal from dies. A multi-ram forging technique was developed to produce marine crankthrows based on numerical simulations and physical modelling. The technique makes use of the structural advantages such that, with only two heatings, the crankpin and the web end can be formed, into shapes as close to the required dimensions as possible. Hence, machining allowances can be greatly reduced and the weight ratio of the crankthrow forging to its machined final part can reach 1.6:1. Thanks to the high material utilization, small allowances, this technique avoids torch cutting, reduces both machining work hours and energy consumption. Compared with other techniques, this technique is easy to operate, more efficient and lowers costs. More importantly, the crankthrows produced with this technique have continuous material flowline, fine structures, which ensures high-quality of crankthrows and their longer service life. Keywords：multi-ram forging; marine crankthrow; numerical simulation; material flowline