Search Results

Effects of high temperature sintering on mechanical properties of sintered low alloy steels were investigated. With regard to sintering temperature dependence of mechanical properties, as-sintered steels are classified into two groups. High temperature sintering increased strength of the group1 steels and ductility of the group2 steels, while it did not affect ductility of the group1 steels and strength of the group2 steels. When these steels were heat treated after sintering, both strength and ductility of the steels obtained by high temperature sintering were superior to those of the steels of a conventional sintering process.

We have developed high efficiency oil pump rotors with a new tooth profile. This profile design is designated intelligent profile rotor (IPR). Its features are: 1. high efficiency by equalized flow rate, 2. reduced sliding which yields less frictional (torque) loss, and 3. lower noise by decreasing the working clearance to 1/3 or less of standard design. We have also improved the dimensional accuracy of sintered rotors, reducing or eliminating machining.

Variable valve timing (VVT) unit, which is able to decrease environmental load and improve fuel economy is loaded onto many automobiles recently. This unit consists mainly of sprocket, housing and rotor. These parts are requested different properties according to environment. We produce sintered parts for variable valve timing unit by selecting compact, sinter process and special treatment according to demanded properties. In this paper, demanded properties of sintered parts for variable valve timing unit and adopted technique to satisfy them are presented.

We have developed a tappet with a cam lobe contacting tip made of a hard sintered material whose base material is cobalt, which adheres less to the steel of camshafts, and which also contains fine particles of tungsten carbide and chrome carbide. We have established a new evaluation method to access wear resistance performance of the tappet. It enables us to measure directly the friction force generated between the cam lobe and tappet and to evaluate anti-scuffing performance with high accuracy because we can clarify the time, load and cam angle at which scuffing occures.