[in Japanese]

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This paper describes hoe to lap the steel balls of less than 1 mm o in large quantity, while keeping them in higher sphericity.
This was found from the analysis of the relative motion between lap disk. and steel ball as well as from the experiments which were made to clear up the relation between the lapping amount and the sphericity.

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It is very difficult to measure the thread pitch and angle in the nut. In this report, the plastic material such as Cu amalgam and dental wax is casted in the nut to obtain a casting for the nut. Its pitch and angle are easily measured, because the casting has external thread. The coefficient of thermal expansion of the dental wax is measured and the aging effect of Cu. amalgam is researched in order to research the source of the error for this measurement. As the result, Cu amalgam is preferable to the dental wax for the measurement of the nut.

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In metal cutting, the cooling effect of coolant from chip side on the tool-chip interface temperature is analysed by a difference method, under the assumption that -the heat transferred by conduction in the direction of motion of chip may be neglected. The tem- perature rise θ at any point on the tool-chip contact plane (heat source) is given by the following expressions :
θ = θ_de^-An, where, A= 0.0044 (θ_s/φt₂) 0.5 (ht₂) 0.57, n=100 am/V_ft²₂= (25/L) (m/t) ₂
The suffix a' is for dry cutting (h=0), and analysis showed that θ_d is equal to the Jeager's solution solved for a semi-infinite body, when V_f and t₂ are not very small.In the above, symbols are as follows : h : the value depended upon a cooling power of fluid α /K, α : heat transfer coefficient, K : thermal conductivity of chip materials, a : thermal diffusivity of chip, t₂ : thickness of chip, V_f : chip velocity, m : contact length of tool and chip, L : peclet number V_fm/4a.

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There have been several theories of chip curl, such as “bending moment theory” and “temperature theory.” However, they are not satisfactory enough to explain Various phenomena which come out in actual metal machining.
Here in this paper, several contradictions involved in the conventional theories have been pointed out after some machining tests. The systematic tests carried out by the author have necessitated introduction of a new factor, that is, shear strain conductivity, which is a motive force of chip curl.
Based upon such an idea, an equation of chip curl for orthogonal cutting has been introduced.
In part 1 some basic ideas have been presented and also discussed, while in part 2 this theory will be insured experimentally.

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