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Recently, powder metal parts have been used in a lot of automobiles. One typical powder metal part is a helical gear. Compacting helical gears is much different from conventional compacting, because a part of the tool rotates on its own axis. The important points are as follows: (1) how to guide the upper punch into a die smoothly and to fit in it, (2) how to rotate the die/punch smoothly in order that the part of gear trains may not be broken by twisting stress during pressing process and (3) how to prevent green compacts from having crack/lamination. The larger the helix angle, the more difficult its compacting. The compacting of complicated shapes such as helical gears with an irregular shape or another helical gear is more difficult. Powder metal helical gears are produced because powder metal is suitable for mass production at low cost. Most powder metal helical gears are simple shapes such as helical gears only outside or inside.

Multi-level compaction is a key technology for manufacturing P/M parts. It requires the development of tool-adaptors, presses, tool materials and construction methods. P/M tools made from high speed steel with multi-platen adaptors combined with a large capacity hydraulic press can produce near net shape, multi-level P/M synchronizer hubs from high strength materials.

Oil-pump rotors with a trochoidal tooth shape have many advantages compared with others, but the trochoidal tooth shape has not been sufficiently analyzed theoretically. So it is very difficult for the pump designer to decide the specifications for the trochoidal tooth shape, and it is also difficult for the supplier to meet the pump designer's requirements. We have been conducting theoretical analyses of trochoidal gears for several years, and have developed a system for designing the tooth shape. We can rapidly design the tooth shape, which meets the requirements of the pump designer, and develop the market for trochoidal gears by using this system. This paper shows the outline of the theoretical analysis, the outline of oil-pump rotors attached to crank shafts in automobiles as an example of the development of trochoidal gears, and some test results.