Kouitsu Miyachika

Limit transmissible torque in the traction drive of a concave and convex roller pair

This paper presents a study on the limit transmissible torque in the traction drive of concave-convex roller pair. The transmitted torque, the specific sliding, the roller surface temperature and the oil film formation under different contact pressures and roller speeds were simultaneously measured by carrying out a concave-convex roller test. Effect of the lubricant on the limit transmissible torque of the concave-convex roller pair was investigated. Furthermore, the experimental results were compared with the theoretical ones based on the thermal elastohydrodynamic lubrication theory, which takes account of the effects of viscous heating and Eyring viscosity. Close agreement between the theoretical and experimental results was obtained.

Effects of Rim and Web Thicknesses on Root Stresses of Thin-Rimmed Helical Gear

This paper presents a study on root stresses of thin-rimmed helical gears with web arrangement of various rim and web thickness. Thin-rimmed helical gears used in this study were meshed with solid helical gear. Root stresses were measured from the beginning of engagement to the end of engagement by using the strain gauge method. The changes of root stresses from the beginning of engagement to the end of engagement were examined and the meshing position where the maximum root stress occurred (worst loading position) was determined. Effects of rim and web thickness on the root stress, the maximum root stress and the position of maximum root stress were clarified.

Residual Stress and Bending Fatigue Strength of Case-Carburized Thin-Rimmed Spur Gears With Asymmetric Web Arrangement

This paper presents a study on effects of carburized parts on residual stress and bending fatigue strength of case-carburized thin-rimmed spur gears with asymmetric web arrangement. A heat conduction analysis and an elastic-plastic stress analysis for the case-carburizing process of thin-rimmed spur gears with asymmetric web arrangement were carried out by the three-dimensional finite-element method (3D-FEM), and then residual stresses were obtained. Effects of the case depth, the carburized part and the rim thickness on the residual stress of case-carburized thin-rimmed spur gears were determined. Bending fatigue tests were carried out for case-carburized thin-rimmed spur gears with asymmetric web arrangement, and S-N curves and bending fatigue limit loads were obtained. Effects of the case-depth, the carburized part and the rim thickness on the bending fatigue strength of the case-carburized thin-rimmed spur gear with asymmetric web arrangement were determined.Copyright

Effects of Heating Conditions on Residual Stresses, Hardened Layers and Bending Fatigue Strength of Induction Hardened Gears

This paper presents a study on effects of heating conditions on residual stresses, hardened layers and bending fatigue strengths of induction hardened gears. Residual stresses and hardened layers of gears induction hardened under various heating conditions were calculated by means of the induction-hardening simulator, which had been developed by authors. Measurements of hardened layers and bending fatigue tests of gears induction hardened under various heating conditions were carried out. Calculated hardened layers were compared with measured ones. The optimum heating condition for the bending fatigue strength of induction-hardened gears was examined.© 2003 ASME

Heat Generation, Power Transmission Efficiency, and Life of Plastic Worm and Helical Wheels Meshed With Steel Worm

This paper describes the heat generation, power transmission efficiency, and life of plastic helical and worm wheels meshed with a steel worm. A machine for testing plastic worm gears was developed, in which the center distance and shaft angle are variable, and by which the transmission efficiency can be measured. Experiments were performed using plastic helical and worm wheels and steel worms under no-lubrication condition. Polyacetal homopolymer and copolymer were used as wheel materials. The tooth temperatures of the plastic helical and worm wheels and the torques of the worm and wheel shafts were measured. The failure mode for plastic helical and worm wheels; the temperature of the wheel teeth; the transmission efficiencies between meshing gear teeth; and the lives of plastic wheels were determined. The effects of backlash and shaft angle on the life of plastic wheels were also determined.© 2011 ASME

Effects of Case Depth, Side-Face Carburizing and Helix Angle on Residual Stress and Bending Fatigue Strength of Case-Carburized Helical Gears

This paper presents a study on effects of case depth, side-face carburizing and helix angle on the residual stress and the bending fatigue strength of case-carburized helical gears. The carbon content of each element of the FEM gear models due to carburizing was obtained. A heat conduction analysis and an elastic-plastic stress analysis in the case-carburizing process of helical gears were carried out by the three-dimensional finite-element method, and then residual stresses were obtained. Effects of the case depth, the side-face carburizing, the helix angle and the face width on the residual stress of case-carburized helical gears were determined. Bending fatigue tests were carried out for case-carburized helical gears and S-N curves and bending fatigue limit loads were obtained. Effects of the case-depth, the side-face carburizing and the helix angle on the bending fatigue strength of the case-carburized helical gear were determined.Copyright

Effects of Heating Time, Electric Power and Frequency on Bending Fatigue Strength of Induction Hardened Gears

The measurement of hardened layer and the bending fatigue test of S35C and S45C steel gears induction-hardened under various heating conditions were carried out, and then profiles of hardened layer and S-N curves (bending fatigue strength) were obtained. Effects of the heating time, the electric power and the frequency on profiles and micro-structures of hardened layers of gears were examined. Relationship between the bending fatigue strength and the profile of hardened layer was determined. Optimum heating conditions for the bending fatigue strength of induction-hardened S35C and S45C steel gears were indicated.

Contact Fatigue Strength and Wear Characteristics of Plasma-Carburized Rollers

In the plasma-carburizing method, the detrimental grain boundary oxides in the surface of the materials and sooting problems are eliminated and the high carbon content near the surface is easily achieved. This paper describes a study on the contact fatigue strength and wear characteristics of plasma-carburized rollers. Test rollers made of super-carburizing steel MAC14 and conventional carburizing steel SCM415 were plasma-super-carburized under different carburizing conditions. The contact fatigue tests were carried out for these plasma-super-carburized rollers. The effects of case depths on the contact fatigue strength of these rollers were determined. The effect of shot-peening on the contact fatigue strength was also examined by carrying out contact fatigue tests for shot-peened rollers. The wear tests were also carried out and then the wear characteristics of test rollers were determined. These test results for plasma-super-carburized rollers were compared with the results for gas-super- or gas-eutectoid-carburized rollers.

Simulation of Induction Hardening Process of Sintered Metal Shafts

A FEM simulation program for induction hardening of sintered metal shafts was made up. Physical properties of the sintered metal were measured. An electromagnetic field analysis, a heat conduction analysis and an elastic-plastic stress analysis during the induction hardening process of sintered metal shafts were carried out for various hardening conditions by using the measured material data and the simulation program. The effects of the electric power and the frequency on the temperature and the stress during the induction hardening process of the sintered metal shaft and the residual stress were examined. The map for selecting the optimum heating condition (P, f) for the residual stress of the sintered metal shaft due to the induction hardening was indicated.

Friction and Wear Characteristics of Natural Iron Sand Coating

Friction and wear characteristics of natural iron sand coating were experimentally examined in the absence of lubricant. The friction motion was not be continuous, but be intermittent and proceeded by a process of stick-slip. An oxide film, Fe2 O3 , was formed along the sliding marks, but the amount of coating worn away was slight. There is a striking similarity in the friction coefficient between the zinc/iron sand coating and MoS2 over a load range of 20N to 1000N. The iron sand coating has a spongy structure and the bonding strength between the iron sand particles is so small that the metallic junction formed between sliding surfaces may be weaker than the substrate. Consequently the amount of metal removed may be small. In addition, the oxide film formed on coating is so soft and fluid that it may in itself function as lubricants and may play little part in abrading the other surface.Copyright