Yasushi Mochida

Estimation of Grinding Wheel Performance by Dressing Force Measurement

Dressing force measuring equipment was developed and the performance of a single-point diamond dresser was examined focusing on the relationship between dressing force and grinding performance. It was found that a distinct relationship exists between dressing force and grinding performance, and that the sharp-edged single-point diamond dresser can control grinding performance with low dressing force. The single-point diamond dresser and multipoint diamond rotary dresser induce the same dressing force if their wear widths are equal.

Performance of Newly Developed Single-Point Diamond Dresser in Terms of Cutting-Point Rake Angle

A cutting-tool-type single-point diamond dresser, the tip of which has a given rake angle, was developed and its dressing and grinding performances were investigated. It was found that the dressing mechanism changes its mode from a ductile mode to a brittle mode with increasing back rake angle in the negative direction and that the cutting-tool-type dresser exhibits good robustness owing to the fact that its ground surface roughness is not markedly affected by the dressing conditions.

Evaluation of diamond dressers and estimation of grinding performance by dressing force measurement

Equipment to measure the dressing force exerted by diamond dressers was developed and the performances of two types of diamond dresser, a single-point dresser and a multipoint rotary dresser, were examined focusing on the relationship between dressing force and grinding performance. It was found that both types of diamond dresser induce the same dressing force if their wear widths are equal and that a strong relationship exists between dressing force and grinding performance; a sharp-edged single-point diamond dresser can be used to control grinding performance with a low dressing force. The truing accuracy depends on the dresser type and a lower dressing force results in better truing accuracy.

Study on the High-Efficiency Smoothness Grinding of Soft Magnetic Powder Cores

Soft magnetic powder cores are materials manufactured by pressing pure iron powder covered with insulating film into shape. These are widely known soft magnetic materials which are used as essential electromagnetic conversion parts in automobiles and household appliances. In recent years, demand for higher magnetic properties and dimensional precision has been growing with respect to soft magnetic powder cores. It has therefore become necessary to develop a high-efficiency, high-precision finishing method. The issues to be addressed with regard to this kind of method are: (1) the pure iron used in these materials displays ductility resulting in burring and cohesion to machining tools, (2) these materials are green compacts with low binding forces between powder particles and high tendencies towards cracking and gouging, and (3) these materials possess residual pores at levels of several percent thus resulting in microscopically intermittent processing which causes heavy machining tool wear. We have solved these issues through the development of a super-smooth finishing method designed for soft magnetic powder cores.

Wear Characteristics of Various Diamond Tools in Cutting of Tungsten Carbide

Face cutting of tungsten carbide was conducted using two monocrystalline diamond tools and three polycrystalline diamond tools to investigate the wear characteristics in terms of the crystal structure and composition of the diamond. It was found that the wear of the monocrystalline diamond tool depends on the crystal planes that form the rake face and flank face of the cutting tool, and a cleavage fracture occurs when the cutting force acts as a shear force on the (111) crystal plane. The binderless nano-polycrystalline diamond tool exhibits excellent wear resistance beyond those of the sintered polycrystalline diamond tool and chemical vapour deposition polycrystalline diamond tool, as well as better wear resistance than the monocrystalline diamond tool.

Improvement of super low core-loss soft magnetic materials

In the previous work, we reported a P/M soft magnetic material with super low core loss value of W10/1k = 68 W/kg which is lower than that of 0.35mm-thick flat rolled soft magnetic laminated steel sheets. But this material lack of strength characteristics due to spherical particles produced by a gas-atomizing method. That is, the value of transverse rupture strength (TRS) was only 20MPa when a non-hygroscopicity resin was used as binder. In order to achieve both low core loss and high strength, the iron powder (shape, surface morphology) and binder strength was improved, and we were able to obtain a material with TRS of 80 MPa and core loss (W10/1k) of 108 W/kg of. Furthermore, by using this binder system, we were able to obtain a TRS of over 50MPa for the material with spherical particles (W10/1k = 81 W/kg).