The present paper deals with the determination of the best cutting conditions in the case of fine cutting of pearlite cast iron, which is used as cylinder material of the internal combustion engine, by tungsten carbide tools, and it contains experimental studies classified into two parts. In Part 1, by means of fine boring with jig borer, the best cutting conditions (cutting speed, depth of cut, feed, and nose radius of tool) were decided from the view-point of the roughness of machined surface and the wear of cutting edge. In Part 2, in the case of fine turning by several kinds of tungsten carbide tools having different chemical components and microstructures, the best kind of tool material was found in consideration of the surface roughness and the tool wear as described in Part 1.

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Orthogonal dry cutting of soft metals such as lead and Lipowitz alloy in low speed with a specially designed cutting test equipment leads to the following results : (1) There exists the "flow region" between the rigid region of workpiece and the plastic region of steady chip. (2) The flow region associated with simple continuous chip is various in shape and size according to cutting conditions. Sometimes it changes periodically during cutting. Moreover, the higher the cutting speed, the narrower the flow region. (3) In the case of discontinuous chip, there exists the flow region during formation of one chip fragment. Fracture occurs near the ending boundary in flow region, and is convex upward.

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This paper describes the experimental research concerning the wear of high speed steel tools. By orthogonal cutting of mild steel with a specially designed tool, we tried to find the process of the wear, especially flank wear and crater wear, the tool contour at the end of tool life, the effect of cutting conditions on the tool wear, and so on. As a result, we obtained the following facts : (1) The best way to express the wear of high speed steel tool is to measure the wear volume. (2) The development of flank wear and crater wear is not continuous. (3) From the standpoint of wear, it is preferable to use large rake angle and clearance angle as far as chattering of tool is not induced. (4) In general, built-up edge does not protect the tool point from wear.

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The tear type roughness of the machined surface, which is considered to be produced by remains of fragments of falling-off built-up edge on the surface, can be diminished by using the specially designed tool with a land of negative relief angle. This paper deals with the outline of the specia1 tool design and, in comparison with the surface roughness of carbon-and chromium steels cut with the special-b and ordinary tools, the most suitable form of the land of negative relief angle was determined experimentally in the case of steel cutting associated with built-up edge. The cutting forces of this special tool are lower than those of the ordinary tool under the cutting speed lower than the maximum critical speed at which the built-up edge seems to disappear, and the cutting ratio is smaller. Moreover, the chip produced has the strong tendency to be discontinuous and the tool has the anti-chatter effect.

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Several experimental results of a research on ceramics as cutting tools are described in this paper. Mechanical properties, grinding pocedures, cutting characteristics and tool life of ceramics are discussed comparing with those for carbide tools. These results showed that ceramic tools used in this study was inferior a little in hardness, sharpness of cutting edges by grinding and resistance of flank wear to those for carbides, owing to less ductility. On the other hand, it was shown that ceramics had excellent features in cutting characteristics, that is, larger shear angle and less tool-chip contact length, and showed good cratering resistance. Improvement in ductility is mostly desired for increasing usefulness of ceramic tools.

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In this paper, the author mentions the measuring apparatus, theory, and experimental results of a new method for measuring straightness automatically, in which he projects a deflected light obtained from a sliding prism on a measuring plane to a photo-cell surface, and integrating the slight varing voltage arised in the photo-cell on account of the surface slope, and indicates the deviation of the surface as cathode-ray oscillogram without intermission. From the experimental results, it has been made clear that this method is practical.

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For testing plane curves given as a profile curves of templets and the like, the author regards these curves as a series of curves of the Pth degree, 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 ones, or absolute values of coordinates of each dividing points on these curves by using a simple instrument with one or more indicators, and examines whether it is practically applicable.

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The authors observed the electrical resistance between the races and retainer of the ball bearing # 6310 lubricated by oil jet. It has been found that the value of the electrical resistace of the oil film between the surfaces of the bearing varies widely with the resistance connected in series to the measuring circuit. On the other hand, the ratio of the reading of the DC-ammeter when oil film exists, to the reading corresponding to the direct contact of the surfaces is practically independent of the circuit resistance. This ratio can be considered as the rate of duration of break down of the oil film. Further, by varying the capacitance connected parallel to the cicuit resistance, the frequency of break down of the oil film can be estimated. It is concluded that the frequency between inner and outer race is proportional to the number of revolutions and that the frequency between retainer and ball has a constant value due to the mechanical vibration of the retainer.

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Using conformal representation, the oil flow coefficient of the pressure-fed journal bearing with an axial oil gloove is calculated. Though the graphical conformal mapping by Wilcock and Rosenblatt gives merely the data for particular forms of the groove, the cofficient for any value of 1/L and b/L can be obtained by this analytical method where 1 and b are the length and width of the groove, respectively and L is the axial length of the bearing. And also the coefficient for nearly circular hole is simply calculated.

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Succeeding to the research of 1st report⁽¹⁾, the cooling effect of air and the influence of viscosity of oil and rotating speed upon the performances or preloaded ball bearing operated at a high speed under fog lubrication have been investigated. The experimental results obtained are as follows : The tendency of bearing temperature rise under fog lubrication may be explained by the ordinary formula of heat conduction with cooling velocity index. According to the increase of rotating speed of ball bearing, the bearing temperature rises rapidly, while the coefficient of friction increases rather gradually, and the increasing rates of temperature rise and coefficient of friction decrease as the rotating speed increases. The coefficient of friction and bearing temperature change are directly proportional to the oil viscosity at the running temperature of bearing. After all, it is concluded that the fog lubrication contains the oil film lubrication very much in spite of very few amount of oil and the effect of viscosity is predominant.

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In the previous report, some experimental results were deseribed on a system of which theoretical speed ratio (gear motor rev./gear pump rev.) was 1.0. But the system of which theoretical speed ratio is not 1.0 is more available. This paper reports the experimental results of the latter system. Experiments were conducted in the laboratory and then on a turnig gear, crane car and etc. The capacities of the system are 15 〓 in output and 15 kg-m in torque. Experiments showed a good result.

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At first, we study the action between a pair of involute helicoids in a most general form. Now preferring a range of the axial angle adequately to the above general meshing, we can drive the standard meshing that the pitch cylinders are out side each other, touching in a point and the meshing, obtained by a continuous variation of the axial angle from the standard case. For those meshing we construct certain general expressions of the reversible involute gears. These expressions are the foundation for the design of the involute spiral gear.

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There are three typical forms of globoid worms and their wheels, they are : (1) Hindley worms, (2) helical gears and their enveloping worms, (3) plane toothed wheels and their enveloping worms. The surfaces of contact of these worms and wheels can be analyzed mathematically. In this way, with some assumed data we can get their contour lines, and thus it can be said : (1) Concerning to a Hindley worm and its wheel, their surface of contact is formed of two surfaces, the one is a plane which passes the axis of worm and perpendicular to the axis of wheel, and the other is a curved surface which is very resemble to the above mentioned plane and intersects it. The surface of each wheel tooth has two contact lines on the approach side, but on the recess side there is only one. Thus the tooth bearing on this wheel tooth cannot be said good. (2), (3) As for a toothed wheel and its enveloping worm, the surface of contact is in nearly tangential to the circumference of worm surface. The tooth bearing on a wheel tooth is in their center portion, and in good condition. Now we consider the manufacturing process of these wheels and worms. The Hindley worm can be cut by single tools, but cannot be ground by grinding wheels. Its wheel must be cut by specially made hobs, and also cannot be ground. On the contrary, the plane toothed wheel and its enveloping worm can be easily cut by a milling cutter and ground by a grinding wheel of simple form. In constructing these wheels and worms, the Hindley worm and its wheel must be built with very strictly limited allowance, but the plane toothed wheel and its enveloping worm can be built somehow under less restrictions.

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In regard to researches dealing with the sand-particles, in many cases, consideration is generally taken not so much upon their particle-shape as their particle-size. This fact is conceived due to the difficulty of measures to represent the particle-shape in figures. The auther, in his experiments on the influences of the shape of sand particles contained in the fluid inflicted upon the abrasion of the metalic materials to the fluid with sand particles, has endeavoured to apply the various methods of determining the sand-particle shape. Though success as well as failure was observed during the course of his experiment, he has, employing a rather simple measure, which is considered not to be easily effected by the experimental conditions, contrived some means for obtaining the shape factor of particles, and certain relations between the shape factor of particles and particle-size in the case of three kinds of particles of silica sands with representative shapes among : Chikuma silica sand in nearly spherical form, Tokitsu silicas and in rather cubic form and seto silica sand in irregular form with acute edge angles.

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A new method has been developed, as a consequence of analysis of plastic flow in the cold extrusion process of steel. As a result of experimental studies on the effects of tool shape, extrusion speed and heat treatment of work materials, it has been found that the extrusion pressure in this method is reduced by about 40% compared with the usual one. Moreover, the height of work piece has little effect on the extrusion pressure, so that deeper shells can be obtained without danger of buckling the punch. The duoble-action die has proved that this method can be applied to the production of various ferrous shells.

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The new method has been successfully applied to the cold forming process of a wide variety of steels, such as construction steel, nitriding steel, special tool steel, bearing steel, and austenitic stainless steel. As lubrication is vital to the success of this method, friction tests were performed utilizing the compression test of a hollow cylinder. Lubricants with low friction coefficient were chosen and then examined by the extrusion method. As to tool material, high carbon chromium tungsten steel, high speed steel, high carbon high chromium steel and cemented carbide were tested. The cemented carbide punch was able to withstand the stress as high as up to 300 kg/mm².

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The measurement and analysis of plastic flow in the backward extrusion process resulted in discovery of the new die with the movable wall. In backward extruding, the metal of the workpiece is forced to flow in a direction opposite to that of the travel of the punch in contact with the die wall. The movable wall can not only reduce friction between the metal and the wall, but also make it possible to form shells with various kinds of outside shapes such as screw, gear, cone, etc. in one operation. In the preseut paper, the plastic flow of the metal through various shape forming dies was studied by means of the distorted grid lines on the cross-section of the workpiece, and relation between load and stroke in the cold extrusion process of steel, brass, and alminum alloy was measured by the new types of load dynamometers and displacement measuring devices utilizing electric resistance wire.

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