As a basic experiment on gear scoring, the surface temperatures of gear teeth are measured. So far, we can find the experiment for measuring the mean surface temperatures of gear teeth. But it is significant in considering a countermeasure of scoring that from another point of view that we come to know the change of the instantaneous temperature with the change of the meshing position. At our experiment the thermocouple used in our experiment consisted of a constantan pinion and a steel wheel, and the thermoelectricity produced in it was observed by oscilloscope. As a result we reached the following conclusion : (1) On the relation between the meshing position and the surface temperature of gear teeth, the experimental value is nearly equal to the value calculated theoretically. (2) As the surface temperature of gear teeth is largely influenced by the load distribution, it is most desirable for designing the gear that we try to change the profile of gear teeth of lowering the surface temperature most, and to avoid the local contact of gears. (3) The surface temperature of gear teeth rises in proportion to the circumferential speed of gears in the range of lower speed, but in the range of higher speed its change becomes small. Speaking of the influence of loads, the temperature changes in proportion to 1/2 the power of the load, but in the range of higher speed the change becomes small.

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The author has reported by the 3rd report that the viscosity of lubricants and the peripheral speed of the gears remarkably affect the endurance limit of the pitting. Then, the theoretical analysis for hydrodynamic film lubrication is presented in the present report, in which the temperature rise of the oil film and the heat transmission through the surface to the rollers together with the internal friction loss in the oil film are taken into consideration. Further, the measured film thickness, reported in the 4th report, is compared with the above theory on the assumption that the rollers are rigid bodies. It is shown that, with the aid of the above theoretical analysis, the experimental results are explained reasonablly.

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The author has reported already that the lubricating conditions of the gears remarkably affect the endurance limit of the pitting. To explain these phenomena theoretically, the author has analyzed the hydrodynamic lubricating film of the gears, taking into account the elastic deformations of the rolling surfaces and the film temperature. In the present report, however, it is shown that the experimental results for the pitting are reasonablly explained with the aid of the above theoretical analysis. That is, the thicker the theoretical film thickness is, the more the cut-marks of grinding of the gear surfaces remain after the running. Further, if the maximum film pressure calculated on the basis of the above theory is taken instead of Hertz stress, the Wohler curve becomes only one curve under various lubricating conditions. These results show that the pitting must be analyzed with the aid of the hydrodynamic film lubrication theory.

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The authors carried out an experimental investigation on the rolling contact fatigue using a testing machine of a rotating-disc type orginally designed by the authors, in order to find the best combination of materials for reduction gears of marine turbines. The experimental condition was chosen as follows : diameter of test disc=60 mm, rolling speed=4800 rpm without slip, maximum contact pressure=70 kg/mm², temperature of supplied turbine oil=60°C and rate of feed=1cc/sec. The main results are summarized : The fatigue resistance of the wheel material is considerably affected by the cold working effect due to the rolling contact to the mating pinion material. A harder pinion material raises the fatigue resistance of the wheel material to a great extent. The best result is obtained by the combination of materials which show the greatest cold working tendency. The results are clearly explained by measuring the surface flow of the materials and the progress of the surface hardness.

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In some special bearings, there is no utilizable lubricant without water which has the viscosity about one-hundredth of the oil. For the material of water lubricated bearing, it is necessary to find out such material that performs safely and displays a small frictional loss at the boundary lubricating condition. It is the principal object of the present investigation to find out the bearing material usable in the range of the normal to comparative high water temperature. The frictional characteristics, the wearing characteristics, the swelling quality and the thermal expansibility were investigated in the following driving conditions : water temperature rangs from 10 to 90°C, bearing pressure from 2 to 8 kg/cm².

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The thrust gas bearing with porous bushing has the advantage of better stability and larger load capacity. In this paper, the bearing of this type is analyzed theoretically. The authors use "permeability" that identifies the characteristics of porous media, and they introduce "equivalent clearance" and "effective restricting lengths" of porous bushing so that the flow in the bearing with porous bushing may be considered as the two parallel flows. The results of analysis coincided quantitatively and qualitatively with those of the experiments.

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In externally pressurized gas-lubricated circular thrust bearings, the occurrence of depression in the pressure profile is observed under some working conditions. Succeeding the previous paper on the theoretical investigation of the pressure depression, the pressure distribution in externally pressurized circular thrust gas bearings with a circular recess is investigated theoretically by assuming the generation of a normal shock wave in the bearing recess. Good quantitative agreement is found between the analytical results and available experimental data except the case of small bearing clearance height or deep recess. In order to prevent the pressure depression just after the gas supply hole, it is effective to make a round or tapered chamfer at the entrance edge of the hole to the bearing clearance or to make the recess tapered doubly. By these alternations, the shape of pressure distribution becomes flatter so that the load capacity can increase remarkably.

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This report treats the effect of cutting fluids on surface roughness in key-broaching a carbon steel. There are two important factors to affect the surface roughness, that is, chip formation and built-up-edge or welding. Moreover, the surface roughness is a function of the cutting distance, and the latter cause is the more controlling for such the transient phenomenon, which is more emphasized by the transient characteristic of lubrication in wet broaching. Here is derived a coeffi-cient of roughness increase, which can be an index for the evaluation or applicability of the cutting fluids. Another finding is that the effect of a cutting fluid from the aforementioned point of view is closely associated with the ratio [load/wear width] in the four-ball test.

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There were many studies on electrohydraulic forming in which the relationship between the deformation of a special metal and the stored electrical energy was investigated. However, it is necessary for us to explain the correlation between the deformation resistance for each of these metals and the pressures in order to analyze the deformation characteristic of metals. The experiments were carried out by means of pressure gage (BaTiO₃) on deformation pressures and pressure waves which are directly related to the deformation, and further, the shock wave energies were calculated. The efficiency of these apparatuses is mentioned. The clearance between the electrodes creating pressure is short-circuited with several kinds of fine wire, and the influences of the diameters and lengths of the wires are presented. Also in case there exists water only between the electrodes, the influences of electrod diameters and clearances are presented. It is found from experimental results that such cases where the clearance between the electrodes is short-circuited with a fine wire are superior to the case where water is the only pressure source between the electrodes, and that the aluminum wire which has a low boiling point metal is effective. The rise time of pressure wave is about 5μs and its duration is about 15μs. Such forms of pressure wave does not change up to 1 000 joule stored electrical energy. Shorter wires are better than longer wires as pressure sources, however the diameter of wires creating the largest pressure is limited by characteristic of apparatus and the stored electrical energy.

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According to the many papers, explosive forming exhibits unusual features in as much that there is a relative absence of springback owing to the very high pressure of shockwave. The authors measured the springback of explosive bending of brass and aluminium sheets which were tried under the relatively low pressure of blackpowder explosion, ana found that the springback was also less than the statical bending test. The following factors are deemed to be the reasons for the relative absence on springback of explosive forming : (1) Peening effect owing to the residual strain of work hardening caused by the impact to die surface. (2) Local bending over which occurs in the forming process of explosive bending.

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