The true behaviors of cutting edges on the wheel surface, such as shapes, distributions and changings, were studied to make the grinding mechanism clear. The author has studied these behaviors. But about the microstructure of these cutting edges, observations of large magnification have not been done. So in this paper these observations using the phase-difference microscope and the electron-microscope have been described.

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This study was made to clarify some effect of cutting condition and machinability of plastics within the range of flowtype cutting.
The results obtained are as follows :
1. Within the range of 70°100° of cutting angle, the cutting resistance and shear angle are in proportion to the cutting angle.
2. When the depth of cut becomes over O. 05mm, specific cutting resistance comes to he almost constant.
3. As cutting speed becomes higher, cutting resistance decreases and the shear angle increases.

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Internal threads have been generally produced by using cutting machines, such as tapping mach'nes or lathes. A rolling method of threads has been generally used to manufacture external threads.
In this study we tried to roll the internal threads having fine pitch. The authors have made an equipment to roll internal threads using a lathe ; that is, a rolling die is supported on the main spindle of the lathe, and then the tool rest fitted with the thread blank is pushed toward the die by a spring to press the thread blank into the die. The two types of internal threads have been used in the above-mentioned experiment ; one has 1mm pitch and the other 0.5 mm pitch.

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There are many cases when we require the values of the unknown dimensions concerning the profile of the teeth of a gear. For the analysis of the involute tooth profile, Prof. M. Naruse used a toolmaker's microscope, and Prof. T. Nakada two or three rollers.
Inserting trapezoidal measuring prisms in the tooth spaces, the authors performed the analysis without the tedious treatment of transcendental equations or without the limitations of measuring space in microscope. In this paper the errors and the applicable limita tions of their method are described, and some spur wheels are investigated as an example.

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The frictional behavior of some cutting fluids are examined with a four-ball apparatus. The balls for usual four-ball apparatus are made of steel, but in this experiment a steel ball for the upper frictional member and tungsten carbide balls for the lower members are used, because the friction in cutting is the one between steel and tungsten carbide. At the low speed the frictional behaviors between steel and tungsten carbide is somewhat different from the behaviors between the steel each other. The difference is explained in view of the conductivity of heat. At high speed, however, the difference is insignificant.
The effects of chlorine and sulphur are discussed. In the experiment, it is found that the higher the chlorine content, the better frictional behaviors are obtained. The inclusion of sulphur does not improve the frictional behavior, but increase the critical load.

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[in Japanese]

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