For testing spatial curves given as ordinary helixes and the like, the author regards these curves as a series of short spatial curves, and gives both theory and experimental results of a method based on the above principle. In this method, he measures relative errors of these curves compared with the standard or theoretical ones by using a simple instrument with four indicators, and examines whether it is practically applicable.

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This paper describes the experimental results about the relation between the physical properties and the life of ceramic tools, the cutting performance of trial products in comparison with a carbide tool of a steel cutting grade, and optimum tool geometry and cutting condition of ceramic tool, at machining 0.4% carbon steel. The results are as follows : (1) The cutting performance of ceramics is affected by the physical properties of ceramics. (2) The type of failure of ceramic tool is essentially the same as that of carbide tool. (3) It is necessary to choose properly tool geometry and cutting condition of ceramic tool for the increase of tool life.

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This paper reports the effects of additives or the presence of polar radicals on the grinding ratio and the wearing process of the grinding wheel. Steel specimens were plane, being ground with 12 kinds of grinding fluids of emulsion type. These grinding fluids were prepared from spindle oil as the basic-oil and the activation agent as the emulsifying agent. In addition to these, sulphides, chlorides, and their compounds of polar radicals, as the additives, were respectively used. These experiments have revealed the following : The additives with polar radicals bring about the increase of the grinding ratio, but the deformation in the surface of the grinding wheel caused by cross feeding is independent of the use of them. Additives containing sulpher, on the other hand, cause the decrease of deformation. In the case of light grinding, the presence of polar radicals has nothing to do with avoiding the deformation in the profile of the wheel.

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In the last paper concering the same problem, the authors reported on the performances of sintered Ag-W alloy contact polished by a machine based on lapping and also on the mechanism of plane contact of metal pieces. In this paper, the results of the experiments on the polishing of sintered W contacts and the influences of different roughness of contact surfaces and applied load on the electrical contact resistance are discribed. Also the relationships between the applied load and the size of true contact area are deduced by assuming a simple model which represents the profile curve of metal surface. The results of this investigation may be summarized as follows : (1) For sintered alloy contacts mechanical polishing is effective. (2) The contact resistance is proportional to 3/5∼3/4th power of load and 1/5∼1/4th power of surface roughness. (3) True contact areas are presumed to order of 10^-4∼10⁵cm² at range of 0.01∼0.1kg in load, 0.01∼0.1μ in roughness and it is independent of apparent contact area.

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In this report, the operating characteristics and the mechanism of lubrication of high speed tapered roller bearing under lubrication by atomized oil are investigated experimentally and theoretically. As the experimental results about the influence of oil consumption, air consumption, viscosity of oil, load and rotating speed, it has been clarified that the lubrication by atomized oil lessens the friction remarkably and the temperature rise in the suitable condition and the atomized oil lubricates mostly as hydrodynamical lubrication. According to the above mentioned character, the hydrodynamical theory concerning the friction moment and temperature rise of tapered roller bearing has been deduced, and it is confirmed that this theory coincides with the results of experiments moderately well.

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Effects of viscosity and oiliness of lubricant film on its wear property are studied by stick-slip analyzing apparatus. The wear properties of various lubricant films are compared with each other by measuring the increase of friction coefficient during repetition of sliding. As the crlterions for the comparison of wear properties of lubricant films are used both the increase of friction coefficient during repeition of runs on the same track and the critical number of runs when the continuous sliding changes to stick-slip. As the result of experiment it is found that not only the oiliness of lubricant but also its viscosity affects so much on the wear of the film ; low viscosity lubricant film flows more easily than high viscosity film into and wets the before frictional track, preventing the catastrophic rise of friction coefficient.

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In this paper is described how the wear properties of lubricant films are affected by load and speed. The wear property of lubricant film is studied by stick-slip analyser, which allows to find the critical number of runs with no abrupt rise of friction coefficient N_c during repetition of sliding on the same track of lubricated surface. From the experiment it is found that N_c changes in proportion to P^-0.55 (P is load), which is explained to be deduced reasonably when analysing the above relation taking the frictional stress into consideration. Wearing process of thin lubricant film is also analysed and by taking the relation between frictional coefficient and the thickness of lubricant film into consideration, the following relation is obtained ; [numerical formula] where μ=friction coefficient ; μ₀=friction coefficient for abundant quantity of lubricant ; y₀=given thickness of lubricant film ; N=number of runs on the same track ; c₁, c₂=constants.

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Effect of temperature on the wear property of thin lubricant film is studied as continuation of the studies reported before. When the temperature of lubricant film is raised the wear property of the film is in general decreased in proportion to the rise of the temperature, reducing to nil at the transition temperature of the boundary lubricating film. This point is known as the desorption temperature of the absorbed lubricant molecule. When the load is varied the wear property of the film also is decreased in the same way as reported before in Part 2 of this study. Discussions of the correspondency between the effects of load and temperature on the wear property of thin lubricant film are also given.

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In the orthodox method of deep drawing, it is hardly possible to draw the blank with a drawing ratio far above 2.0. The authors deviced a new drawing method, in which using the ordinary solid tools a pressure lubricated condition with almost perfect fluid friction could be established over the die surface. By this method, we easily accomplished a drawing operation with the drawing ratio of 2.58. The mechanism, general characteristics and possibilities of the method are accounted for here.

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The mechanism of deformation in this drawing method is clarified more fully by measuring thickness strains of the material lying around the punch head. Basic characteristics of the deformation consist in the hydroforming-like straining. It is concluded that the possibility of this drawing method in improving the drawing ratio is based rather on such straining character than on the reduction of the drawing load due to the pressure lubrication.

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The running resistance of snow-cars is much larger on snow covered surfaces than that of ordinary automobiles on hard ground surfaces. Consequently the value of the resistance has an important effect upon the running ability of snow cars. The writer investigated this problem, through running tests, by using the 16mm motion pictures and the engine boost pressures, especially making clear the effect of car velocity on the resistance.

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In snowy districts, provided the road surfaces are covered with snow, the running of auto-mobile often gets into trouble due to the increase of road resistance, which sometimes gives rise to problems such as augmentation of fuel consumption, overheating of engine, slip of driving wheels, shortening the lives of parts, and so on. For taking steps to solve these problems, it is essentially important to make clear the values of running resistance. In this report, the relation between the road resistance of automobiles and the snowfall on road surfaces is ascertained.

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