Study on creep-feed grinding of heat-resisting alloy — Influence of grinding wheel wear on grinding speed

Engineering. 1993 Aug; 59(8): 1251-1256. A new efficient magnetic abrasive finishing process is created in which the new type magnetic abrasives are used mixing small sized diamond magnetic abrasives with such large sized ferromagnetic particles as iron particles. From the experiments, it was clarified that the machining efficiency was improved remarkably based on the increasing effects of both the finishing pressure and the magnetic brush rigidity. It was also pointed out that the machining efficiency was influenced severely by both the iron particle diameter and the mixing weight percentage of iron particles, and there was suitable value for the mixing weight percentage. 5 Refs. 66. Maeda, Yukio; Masuda, Masami; Koizumi, Yukihisa; Watanabe, Makoto. Study on creep-feed grinding of heat* resisting alloy - Influence of grlndtng wheel wear on grinding speed. Journal of the Japan Society for Precision Engineering. 1993 Aug; 59(8): 1301-1306. Creep-feed grinding is a form-copying grinding process capable higher rates of material stock removal than most other conventional grinding processes. In industry, creep-feed grinding is used for formcopying grinding of material which is very hard or very tough. The most widespread application of the process is the formcopying grinding of Inconel turbine blades of gas turbines. This paper deals with the grinding wheel speed and grinding ratio aspects of creep-feed grinding of Inconel 738. These aspects were studied under conventional grinding and creep-feed grinding conditions. The following results were obtained. (1) In grinding conditions, the grinding ratio has an especially strong correlation with the grinding speed. The grinding ratio at a low wheel speed of 3 m/s is approximately 10 times larger than that of the conventional wheel speed of 33 m/s. (2) It is made clear that dulling and breaking appear on a grinding wheel at a conventional wheel speed, and self-sharpening appears at a low wheel speed, according to the estimation with the measured mean grain profiles. (3) The wheel wear of the edge part during creep-feed grinding is 4 times less than that of the conventional grinding, with low wheel speed operation. 9 Refs. 67. Magara, T.; Yamada, H.; Yatomi, T.; Kobayashi, K. Study on Improvement of surface straightness In wire EDM. Journal of the Japan Society of Precision Engineering. 1993 Apr; In general, two kinds of shapes are formed on surfaces of workpieces: concave and convex forms. The mechanism of forming these shapes is strongly related to the mechanical behavior of a wire electrode vibrated by discharge reaction forces whose irregularity makes the concave form on the finished-surface. The supply of intermittent voltages prevents long ignition delay time, so that it inhibits the variance of forces on the electrode. Simulation indicated reduction effects of vibration of the wire electrode in the intermittent voltage condition. Straightness of surfaces was also improved by experiment in finish-machining. 68. Ikeno, Junichi; Tani, Yasuhiro. Study on manufacturing method of ultraflne abrasive pellets applying electrophoretic deposition for nanometer grinding. Transactions of the Japan Society of Mechanical Engineers, Part C. 1993 Jun; 59(562): 1946-1951. The realization of a minute grain depth of cut is an important feature for obtaining a supersmooth surface by grinding. It is desirable to apply a grinding wheel composed of uitrafine abrasives which the diameters are $10 to 20 nm, but it is difficult to mold homogeneous one due to cohesion of the grains. We have already reported that homogeneous uitrafine abrasive pellets could be manufactured applying etectrophoretic deposition and that grinding using the pellets accomplished supersmooth surface less than 10 nm Rmax for hard and brittle materials. However, the bonding agent was sodium alginate which was not familiar to grinding wheel makers. Thus the manufacture of ultrafine abrasive pellets using conventional bonding agent was examined in this paper in order to apply their knowledge to production of the pellets. As a result, homogeneous ultrafine abrasive pellets using PVA bonding agents could be developed and accomplished nanometer grinding of silicon wafers. 9 Refs. 69. Okuyama, Shigeki; Yoshida, Thuyoshi; Watanabe, Shoichiro; Kawamura, Suehisa. Study on the corner dullness in surface grinding - mechanism of generating the dullness due to the wheel to workplace relative displacement. Journal of the Japan Society for Precision Engineering. 1993 Aug; 59(8): 1269-1274. Some machine parts, such as cutting tools and shearing blades, have importance in their comer shapes. The corner dullness which deteriorates the corner shapes is often generated at the ends of ground machine parts. This paper deals, both theoretically and experimentally, the mechanism of generating the dullness under one-pass-plunge grinding and following results are obtained. (1) Entrance dullness, being generated at the wheel entrance part, and exit dullness, being generated at the wheel exit part, are different in shape. The height of exit dullness is about three times as much as the entrance. (2) Shapes of the dullness, theoretically obtained under consideration of the wheel-workpiec e relative displacement and utilizing the one-freedom vibration model, show good agreement with measured results. (3) Height of the exit dullness increases with wheel depth of cut, table speed, and grinding stiffness under usual grinding condition. (4) Height of exit dullness decreases with equivalent mass, dumping coefficient, and spring constant of the grinding machine. 7 Refs. 70. Nishihara, Tokuhiko; Okuyama, Shigeki; Kawamura, Suehisa; Hanasaki, Shinsaku. Study on the geometrical accuracy in surface grinding - thermal deformation of workplace in traverse grinding. Journal of the Japan Society for Precision Engineering. 1993 Jul; 59(7): t 145-1150. Thermal deformation of a workplace attracted by a magnetic chuck in traverse grinding is theoretically investigated by a finite element method. The results are compared with the measured profiles of ground surfaces. Necessary force of a magnetic chuck to constrain the warp of workpiece bottom surface is also computed. The main results are as follows: (1) Central part of the workplace bottom surface separates from the magnetic chuck by the thermal stress due to the grinding heat. (2) The local thermal deformation at the central part of a workplace increases with the number of grinding passes. Around the entrance and exit part of each grinding pass, the local thermal bending deformation occurs. (3) The separation of the workplace bottom surface and the local thermal deformation lead to a concave profile of the ground surface. (4) When a workplace of 10 x 60 x 40 mm in dimension is ground under a condition of 10 p.m down feed and 5 mm cross feed per a pass, the necessary constraining force is about 12 MPa. 8 Refs.