Kentaro Tamamura

Burnishing process using a rotating ball-tool — effect of tool material on the burnishing process

Abstract The cylindrical, machined surface of a steel bar was burnished under a rolling contact using a lathe and using a ball as a tool, i.e. a ball-tool; the ball-tool was rotated by the drive of the workpiece mounted on the lathe. To investigate the effect of the tool material on the burnishing process, five types of ball-tools, i.e. cemented carbide, silicon nitride, silicon carbide, alumina ceramic, and bearing steel were used. The burnishing force pressing the ball-tool against the workpiece ranged from 5 to 170 N and the burnishing speed was 100 m min −1 . Although the burnishing (or running) distance was usually short, less than 100 m, the influence of the burnishing distance on the burnishing process was also examined by long-distance burnishing processes, continuously extending over a distance of up to 760 m. The cemented carbide ball-tool accomplished the best results among all types of ball-tools used; it produced the smoothest surface and its own surface was hardly damaged after use for long-distance burnishing. The silicon nitride ceramic ball-tool also produced a smooth surface. Neither, the silicon carbide nor the alumina ceramic ball-tool gave satisfactory results.

Lapping and frictional properties of diamond, and characteristics of diamond cutting tool

Abstract Properties of single crystal diamond on the lapping, the friction and the cutting test (by diamond tool) have been studied with a special reference to the crystallographic orientation of diamond. By a novel apparatus newly designed, the orientation of diamond is identified in terms of X-ray diffraction technique, and other experiments were also conducted with the apparatus as setting the diamond oriented. In the lapping and frictional tests, the forces, the temperatures and the wears are measured. In the cutting tests, the friction between chip and tool rake face is calculated. The diamond reveals its highly anisotropic characteristics in the all tests. On the lapping test of diamond, it is clear that the force ratio, the temperature and coefficient of friction become lowest values in the direction of the {110} plane rather than the other. On the cutting aluminum alloy by diamond cutting tool, the minimum of the cutting force and coefficient of the friction revealed on the rake face which is identified with {110} plane, and its direction on the plane is direction, as same as the case of lapping and frictional examinations.

Effect of Lubricant Fluid on Burnishing Process

A burnishing experiment is performed by forcing a cemented carbide ball or a steel ball through a slightly undersized machined hole, which is the so-called ballizing. The effect of lubricant fluid is studied with the measured ballizing force for steel workpieces. It is found that the viscosity of the fluid has the most marked influence on the process. The deformation of the workpiece material in the surface layer and the state of the tool and the material interface in the process arc also examined. The following observations are made; (1) the height of bulge in front of the tool reaches a few times as large as the finishing allowance and it also depends on the viscosity of the fluid. (2) the “micro shear-flow layer” exists at the burnished material surface, and (3) the effect of the viscosity on the working force and the bulge of the material etc. is closely related with the “micro shear-flow layer”.

Effect of lubricant fluid on plastic metal flow in sliding contact

Abstract Plastic metal flow in surface layers, especially “abnormal metal flow”, in which the direction of metal flow in the inner surface layer is different from that in the layer nearer the surface, in sliding contacts between a pin of cemented carbide and a ring of steel under lubrication is discussed in this paper. Low viscosity mineral oil is used as a base oil. Sulphide and chloride extreme pressure additives are also mixed with the base oil. Such a lubricant has a great influence on the plastic metal flow of a ring. While base oil produces severe plastic metal flow, the sulphide additive causes the plastic metal flow to be very mild. In contrast, a lubricant containing a chloride additive causes abnormal metal flow, where cracks can be seen. Conditions for and causes of abnormal metal flow are investigated.

Effect of EP-additives in grinding oil upon grinding performances - Cylindrical plunge grinding of stainless steels.:Cylindrical Plunge Grinding of Stainless Steels

以上の結果をまとたると,次のようになる.(1)研削比の向上には極圧添加剤の効果は大きい。すなわち,研削比はSの場合が最も大きく,そしてP,C1の順である.(2)SUS304の場合,研削条件が過酷になると凝着を起こし,本実験の場合いかなる添加剤でもそれを防げなかった.しかし,それを軽減する効果はSが最も大きかった.(3)仕上面粗さの向上には,いずれの被削材に対してもPの効果が大きい.(4)研削抵抗はSUS304,SUS440Cのいずれに対しても,P,C1,Sの順に小さくなる傾向があり,特に法線研削抵抗にその傾向が顕著に現れる.(5)本実験条件の範囲内では,SUS440CはSUS304ほど難削材ではない.