The electrical shorts which occur often between the electrode and the work in the electrical discharge machining lower the machining speed. To improve the machining speed we have to release the electrode from contacting the work either by actuating the servo motor controlled by the voltage between the electrode and work or by imparting the displacement to the electrode by actuating the moving armature type servo magnet.
In this paper the displacement of armature have been discussed.
From the equation of motion of the armature we obtained the approximate solution and then calculated the steady displacement of the armature considering it's magnetizing characteristic.
By this study the following points were clarified.
1) The transient response of armature is shorter when the exciting current is put in to the coil than when the exciting current is broken in to the coil.
2) For reducing the response time of armature displacement, the decreasing the electrical current response time is more important than increasing the resonance frequencies of the armature.
3) When the time constant τ_E is several times larger than the value of 2π/ω₀, and at the same time when the steady displacement x_S is smaller than the initial air gap x₀, the displacement response can be given approximately by the following equation.
x=K₂/k (1-ε^1/τ_Et) ² (When the exciting current is put into the coil)
x=K₂/kε^2/τ_E't (When the exciting current is broken in the coil)
Where ω₀ : angular velocity of armature [Rad/sec],
x : armature displacement [m],
K₂ : constant of attractive force [N],
k : spring constant [N/m] and
τ_E : time constant of exciting current [sec].

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This paper deals with the characteristics of the three components of cutting forces and their distributions along cutting lips in gun drilling. Experiments are carried out by machining three work materials (carbon steel, duralumin and cast iron) with forming tools.
The main results ars as follows.
(1) The distribution of each force, especially thrust force on gun drills is more uniform than that on twist drills.
(2) The centralized cutting force is observed at the apex point of tool lips, but it is harmless compared with the effective action to seperate chips.
(3) The factors affecting the distributions of forces are considered the form of chips and built-up-edge effected by the difference of cutting speed along lips.

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Although a great quantity of Si single crystal have been used as semiconductor materials in electronic circuits, serious problems still remain for obtaining the mirror-finished surfaces with scratch-free and non-deformed layer. It is most important for mirror-finished Si surfaces to clarify the forming mechanism of mirror-finish. Taking these into considerations, Si single crystals are lapped under the various working conditions, and their characteristics are discussed concerning the mechanism of mirror lapping.
The results are as follows : (1) In case of bonded abrasives, the mirror finished surfaces are formed as the aggregation of fine scratches, for both restriction of abrasive behavior and irregularly sized cutting edges, and fine scratches are not removed. (2) With fine loose abrasives (size about 0.1μ), the mirror finished surfaces are produced, on which no scratch is observed under the electron microscope (×4000). (3) As to the mirror finish, pitch lap is superior to other laps, but the long time required for working. (4) By PE lap, finishing surface roughness is about 0.1μ (H_max). As working time takes short, this lap is suited to produce pre-treated surface of scratch-free mirror finish.

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In order to observe orthogonal cutting phenomenon of gray iron at a low speed (v=40mm/min) accurately, the side view of the metal cutting process was continuously photographed through a microscope by a motor-driven 35mm camera with a pair of cynchronized flash light source.
Cutting resistance and surface roughness were also measured so that these terms were studied with reference to the type of the chip formation.
From the test data, it was found that three types of the chip formation : namely the crack, shear and tear types, occurred alternately in machining of gray iron. The shear type occurred more frequently than other types. Surface roughness produced by the crack and tear type chip formation was greater than that by the shear type. A decreased tool rake angle resulted in the increased surface roughness, and a more dominance of the sh2ar type chip formation to other types.

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Machinability of calcium deoxidized steel is studied in turning by comparing with that of silicium deoxidized steel. Tool life, roughness of machined surface and cutting mechanism are examined on these two kinds of steel. It is found that tool life of carbide tool in turning calcium deoxidized steel is apparently longer than that with silicium deoxidized steel, though surface roughness and cutting mechanism in cutting both steels are almost similar. Observation by X-ray microanalyser indicates formation of the thin surface film containing calcium, manganese and alminum on the tool face used for cutting calcium deoxidized steel. It is considered that the film is effective for protection of tool wear. Furthermore, it is shown that there exists the optimum content of calcium in calcium deoxidized steel to give the longest tool life. Tool life of cermet tool is improved on calcium deoxidized steel, though that of high speed steel tool shows no significant difference in turning both steels.

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The effects of vibrational direction in ultrasonic grinding by using the ultrasonically vibrated workpiece were investigated (amplitude : max. 20μ, frequency : 26kc/s, workpiece : austenitic stainless steel).
In this paper, the relations between the stock removal and grinding conditions are described.
The main results are as follows.
(1) Regardless of vibrational direction in ultrasonic grinding, the stock removal is larger than that in conventional grinding method.
(2) The experimental relation between the stock removal and normal feeding force is expressed by the equation V_m∞P, where V_m : stock removal in ultrasonic grinding, P : normal feeding force.
(3) The stock removal in ultrasonic grinding is influenced by the speed ratio πaf/v_w and vibrational direction, where a : amplitude, f : frequency, v_w : rotating speed of gridning wheel.
(4) The critical grinding speed occurs in using the workpiece that vibrates to the grinding direction. Nevertheless, the stock removal at the higher grinding speed than the critical one is larger than that in conventional grinding method.

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[in Japanese]

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[in Japanese]

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