This paper experimentally describes the grinding characteristic of segmental wheels in creep feed grinding. In creep feed grinding, grinding temperature increases rapidly and thermal damage such as a burn occurs on a workpiece. As one of prevention methods of the thermal damage, a segmental wheel which shows an excellent cooling effect has been developed. This wheel has 24 pieces of soft grade segments which are attached on the circumference of an aluminium disk. As a result of applications of the segmental wheel to creep feed grinding, the followings became evident. (1) The segmental wheel has the effect of reduction of both total grinding force and grinding temperature. (2) Self-sharpening is activated and grinding characteristic of the segmental wheel is kept good without dulling of cutting edge. (3) Grinding ratio and ground surface roughness in the case of a segmental wheel is almost the same level as those in the case of a straight wheel.

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This paper describes the loading of soft grade wheel and effects of removal of loading chips on grinding performance. In creep feed grinding, chips are long, thin and curled. The chips loaded into wheel pores, therefore, are not removed easily, and are remained. Such loading chips have adversely effects upon the grinding performance. Soft grade wheel which is effective to prevent dulling has large pores, so that it seems that the wheel is effective to prevent loading, too. In this paper, loaded area rate which is the ratio of loaded area to wheel surface area is measured by reflected light intensity method in creep feed grinding with the soft grade wheel, and influence of wheel depth of cut and wheel grade on loaded area rate is clarified. For the improvement of grinding performance, furthermore, loading chips are removed with high pressure grinding fluid supply unit and specially-made nozzle. As a result of investigation, the followings became evident. (1) Loaded area rate increases with a rise in wheel depth of cut or wheel grade. (2) In the case of the soft grade wheel, removal of loading chips is effective in reducing a wheel wear, but is not effective in reducing a grinding force.

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This paper describes influence of a land ratio and a number of land on the grinding characteristic of segmental wheels in creep feed grinding experimentally and theoretically. It has been proved that segmental wheels have the effect of reductions in grinding force, grinding temperature and wheel wear. However, these merits of segmental wheels are not available without both the optimum land ratio and the optimum number of lands which are appropriate to a given grinding condition. Practically, these optimum conditions are determined by the method of trial and error. As a result of experiments and theoretical analyses of cutting force and wear, the followings became evident. (1) The optimum condition exists in combinations of the land ratio and the number of lands. At this condition, grinding force and wheel wear are reduced to a minimum. (2) Cutting force per one cutting edge has a maximum at a front part of a land, and is reduced at rearward part of the land. Therefore, the wear behavior of cutting edge on the land varies with its position. (3) The optimum condition of the land ratio and the number of lands can be determined according to the theoretical analyses.

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Diamond wheels must be correctly prepared in order to give optimum results in grinding. This preparation will be sufficed by only truing operation for diamond vitrified wheels. This paper first describes a brief investigation of truing performance on the most widely used truing techniques for preparing vitrified wheels. The main obtained results are as follows : (1) Single-point diamond tool or diamond impregnated tool has a comparatively high efficiency in truing but cannot derive a satisfactory grinding performance from the diamond wheel. SEM observations shows that the wheel surface trued by these techniques contains numerous grains with flat plateaux. (2) Diamond wheel after truing with a silicon carbide brake truer has a higher performance in grinding but remains out of round by 2-3 μm. On the basis of these results a new technique with GC cup truer is proposed in the rest of this paper. This device consists of a silicon carbide wheel with the axis perpendicular to the grinder table. This technique is discussed in detail and proved to be satisfactory in truing effect and efficiency.

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サファイアの硬度は非常に高く加工効率の向上が困難とされる。そこで、ELID研削法を利用し、日接着冶具によるを行ない高能率加工の調査を行う。

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This paper presents the experimental investigation on the wear characteristics of CBN wheels in creep feed grinding. The obtained results are as follows : (1) As the wheel depth of cut decreases at a constant stock removal rate, the grinding force per a grain cutting edge f_ts increases almost power functionally and the mechanism of wheel wear changes rapidly from the attrition type to the micro-fracture type when the f_ts value exceeds a critical value f_ts (c). (2) The volumetric wheel wear rate takes a minimum value at the critical condition.

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reep-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 form-copying grinding of material which is very hard or very tough. The most widespread application of the process is the form-copying 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.

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Creep-feed grinding has been considered to be far more advantageous than the conventional swing grinding, especially with regard to wheel wear. However, the validity of the inference has not yet necessarily been made clear experimentally. In this study, some characteristics of wheel wear in creep-feed grinding were investigated experimentally comparing with the ones of the conventional swing grinding under similar metal removal rate conditions. The results obtained here are as follow : (1) Creep-feed grinding is not necessarily more advantageous than the conventional grinding with respect to attritious wear of the grinding wheel. (2) Creep-feed grinding is effective for holding the sharp profile of the grinding wheel due to reduced impact force at the edges of the work.

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In creep feed grinding of hardened tool steels with straight and V-shaped grinding wheel, abrasive cutoff of mild steel and deep slot grinding with cutoff wheel, the effects of dressing condition, operating parameters and especially wheel speed on radial wheel wear are investigated experimentally. The following phenomena are clarified. (1) The optimum wheel speed when radial wheel wear becomes smallest exists and it varies with workpiece material, characteristics of wheel, dressing condition and operating parameters. (2) The finer dressing condition is or the larger work speed and wheel depth are, the lower the range of the optimum wheel speed is and the narrower it is. There are some cases where the optimum wheel speed becomes about one hundred meter a minute in case of fine dressed wheel. (3) In abrasive cutoff of mild steel, the optimum wheel speed is determined by workpiece thickness and work feed speed.

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This paper describes the availability of soft grade wheels in creep feed grinding. In creep feed grinding, both an increase in grinding force and a burn become serious problems because of loading and dulling on wheel. As one of the methods of improving these problems, maintenance of grinding performance by activating self-sharpening has been proposed. In order to activate self-sharpening, the following two attempts are performed. The first is to increase cutting force per cutting edge. The second is to use a soft grade wheel. From grinding tests with soft grade (C-E) wheels, influences of grinding conditions on wheel wear and grinding force are investigated. As a result of investigations, it is evident that the use of a soft grade wheel under optimum grinding condition is effective and suitable for the creep feed grinding.

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