[in Japanese]

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When a solid body begins to slide on a vibrating surface, the static friction appears to be reduced. In the present report, the effect of vibration in an arbitrary direction is discussed generally, though in the previous report the special case of the vibration in each direction of three axes of rectangular coordinate has been dealt with.
The analytical results show that the vibration in any direction has the effect to reduce the static friction in appearance and the relation between the apparent coefficient of the static friction effected by vibration in the direction of (ψ, γ, ) that is μ_s', and the ratio of acceleration of vibration to that gravity Λ, is expressed as follows:
Λ=√1+tan²γ/1+μ_s'²·1/μ_s²-tan²γ{√D²-√D²-(μ_s²-tan²γ)(μ_s²-μ'_s²)},
where D= μ'_s.tanγ. cosψ + μ_s², μ_s: the true coefficient of static friction, γ: the angle of vibratory direction made with z-axis, ψ: the angle with x-axis projected on the xy-plane.
When D> 0, the phase of vibration is π/2, at beginning to slide, while when D<0, it is 3 π/2. The most effective direction of vibration to reduce the apparent static friction is as follows: γ= cot^-1μ_s= π/ 2-θ₀ and ψ =0, where θ₀ is the angle of friction, then Λ =sineθ₀.
These theoretical results have been also confirmed in good agreement with that of the experimental studies.

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Hot machining of carbon steel (C 0.45%) and 13Cr stainless steel was carried out with a ceramic cutting tool. Work material in front of the edge of tool was heated locally by electric current through the tungsten electrode and work material. Cutting resistance at hot machining was compared with that at usual cutting. The following is a summary of the results:
1) Cutting resistance for both materials shows small fluctuation at high cutting speed but large fluctuation under a critical cutting speed ; the effect is great if hot machining is made in such a violent fluctuating. sphere.
2) Cutting resistance decreases with the increase of electric current in the range of low cutting speed.
3) The difference of cutting resistance at hot machining and usual cutting is very small at high cutting speed.

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This paper deals with the relation between firing temperature and microstuctures of fractured, lapped and polished surfaces with their crystalline textures in steatite, forsterite, high and low alumina and mullite by the use of electron microscopy and etching technique. The results obtained are summarized as follows:
(1) Defects found on lapped and polished surfaces are 'pores' which occupy 6-20% in area.
(2) Crystal grains are not so much released in polishing of steatite, leading to the easy formation of gloss.
(3) The release of crystal grains on polished forsterite is caused by large thermal expansion and uneven distribution of grains.
(4) Pores in area increase as the firing temperature drops in high alumina.
(5) The rise of firing temperature causes the separation of the texture in grain boundaries, leading to the improvement of gloss in low alumina.
(6) Mullite becomes glossy easily in spite of a high porosity of 11%.
(7) The effect of firing temperatures upon the mechanical and structural properties becomes stronger in the order of low alumina, forsterite, high alumina and steatite, while it is not clear in mullite.

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In preceding papers, the effect of working conditions on loadingwere studied. This article describes the relation betwieen grinding fluid and loading.
The results obtained are:
(1) Dry grinding produces more loading on the worked wheel surface compared with wet grinding.
(2) The conditions of loading changes considerably by the kind of grinding fluid.
(3) The loaded quantities per unit area on the worked wheel surface vary with the difference of cooling, wetting and lubricating.
(4) Lubricating and wetting are more effective than cooling for the loading.

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To standardize the numerical tolerance of cylindrical machine parts with respect to roundness and cylindricity, the tolerances which are actually directed in machine designs in mechanical industry of Japan are investigated by means of questionnaires.
158 answers are obtained. The distinctive relations can not be found out between the tolerances of form errors of machine parts and their dimensions. Then, the answers are classified by machining processes such as cutting, grinding and other special machining, and by industries such as fine instruments, machine tools, industrial machines, transportation machines, optical machines and electrical machines. Geometrical mean values of the tolerances and the dimensions at every five points from the smallest to the largest machine parts are calculated, and running mean values at every five points of the geometrical mean values from the smallest one to the largest are calculated on each classified item individually. As the results, it is distinctly recognized that there are differences between the tolerances of the respective machining processes and also between the tolerances of the respective industries, and that the tolerances are put under such simple rules that the tolerances of roundness and cylindricity versus diameters of machine parts are given by Ai and the tolerances of cylindricity versus length of machine parts are given by Bi2/3 in the case that length over diameter is more than three, where i is the tolerance unit in ISO System of Limits and Fits, i_L, is the value given by length instead of diameter in the tolerance unit, and A and B are constants as regard to machineing processes.

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