JPMA awards 2017
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Fig. 2 Sumitomo Electric Industries Ltd. received an award for its development of this complex pulley with high-accuracy non-circular gear teeth
assembly. Additionally, production of the pulley had to correspond to the requirements for future globalisation in production. Uneven density after compaction and deformation due to sintering were identified as factors affecting external teeth accuracy. These were resolved by optimising the sizing conditions. Four oil-passing slots were formed by long and thin side cores in the tool-set; however, this led to the breakage of these side-cores after the compaction of around 500 parts. Therefore, two measures were taken; improvements were made to the side-core design to enhance rigidity, and side-core extraction during green compact ejection was delayed. Eventually, the mass production of large parts having high accuracy non-circular gear tooth surfaces was achieved by optimising production conditions. It is expected that, in the future, demand for sintered pulleys with non-circular gear teeth for VCTs will expand greatly, particularly in Europe. Development of a sprocket drive for a low fuel consumption automatic transmission (AT) oil pump Diamet Corporation was awarded a prize for its development of a sprocket drive for a next-generation fuel consumption AT oil pump (Fig. 3). From a cost point of view, an Fe-Cu-C based sintered sprocket with 6.8g/cm3 density was used for this unit, instead of a fine-blanked sprocket. Although induction hardening treatment is often used for gear tooth surface hardening, post-processing is required since dimensional accuracy deteriorates. In order to achieve both mechanical strength and low cost, Diamet has tried to improve the dimensional precision of an as-induction hardened body. By setting the sizing conditions to minimise residual stress, it was possible to reduce the deformation during induction hardening and to achieve the required parallelism, with a dimensional accuracy of 50 μm, without post-processing.
Fig. 3 A sprocket drive for a low fuel consumption automatic transmission oil pump
that these technologies will be applied to global production in the future. Development of a complex shaped pulley with high-accuracy noncircular gear teeth Sumitomo Electric Industries Ltd. received a prize for a pulley with non-circular - in this case, triangular - gear teeth, which is a part of a VTC in a 3-cylinder engine (Fig. 2). The part was developed to achieve a reduction in vibration.
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Powder Metallurgy Review
To deliver the required improvements in function, a complex shape and high dimensional accuracy had to be achieved. High accuracy was required to achieve the extremely tight geometrical tolerances of the non-circular external teeth (the outer diameter, the whole circumference, profile and squareness). In relation to the shape requirements, the female screw holes and oil passing slots had to be formed, taking into account the subsequent
Winter 2017
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