The paper deals with the recent changes in techniques for manufacture process, together with the investigation results on both semi built-up type and solid type crankshafts to meet the requirements of engine designer's.
The first part in the paper deals with the particulars of semi built-up type cast steel crankshafts. After a short description of the manufacture method and its mechanical properties, some of the recent investigation results are given. It includes a description of the test results on the effects of included defects in the material on the fatigue strength, the favorable effects of a fillets cold roll treatment and also the fatigue strength of actual crankshafts.
The second part deals with solid type crankshafts. It describes full details of the RR forging unit renewed fundamentally in 1969 by our own design work and drawings, and also the forging process of RR crankshafts.
A description is then given of the special features in their utilities as well as of their mechanical and fatigue properties associated with the RR forging process. It shows why the RR crankshafts are superior, or are well adapted for high performance Diesel engines.
In the last stage, it gives a brief description on the decrease of the modulus of RR crankshafts up to 15 per cent than the shafts made by slab forging process, which have been approved by several Classification Societies.
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