Komei Fujita

Effects of tooth profile on scoring behavior in spur gears.

To find out a fundamental tooth profile design policy for the scoring of spur gears, the effects of tooth profiles on scoring behavior were examined taking account of the two-cylinder test results. The tip interference on the approach side markedly affects the scoring phenomena. Both the reduction of the maximum specific sliding on the geometrical working flanks and the avoidance of tip interference on the approach side are the essential conditions to obtain spur gears having superior scoring load capacity. In the mixed lubrication state, where the scoring occurrence has an intimate relation with the working flank bulk temperature, the scoring bulk temperature of a spur gear pair with no tip interference on the approach side can be estimated well by the bulk temperature on the outer surface of the cylinder immediately before seizure in two-cylinder tests.

Surface durability and surface failure of a thermally refined steel roller using a specific sliding varying type contact roller testing machine.

Thermally refined steel rollers were fatigue-tested under three sliding-rolling contact conditions while varying specific sliding during the rotation of a test roller, using a newly produced specific sliding varying type contact roller testing machine, and the surface durability under each condition was elucidated. The test results obtained under these varying specific sliding conditions were compared with the results obtained by a conventional rolling contact fatigue test with a constant specific sliding. The relationships between the characteristics such frictional torque change under each varying specific sliding condition and the surface roughness and pitting distribution on test rollers were discussed. The surface durabilities under varying specific sliding conditions were lower than those under a constant specific sliding condition. The roller surface roughness tended to be lower at a position of higher absolute value of specific sliding, and the pitting tended to be more formed at a position of higher absolute value of frictional torque.

Surface durability and surface failure of nitrided steel roller by using a specific sliding varying type contact roller testing machine.

Nitrided steel rollers were fatigue-tested under three kinds of specific sliding varying conditions using a specific sliding varying type contact roller testing machine. The surface durability under each condition was elucidated. The test results under these specific sliding varying conditions were compared with the result obtained under a constant specific sliding condition. The relationships between the characteristics such as frictional torque change and the spalling failure and surface roughness on the rollers were examined. The surface durabilities under specific sliding varying conditions were lower than that under a constant specific sliding condition. The spalling failure tended to occur at a position of higher absolute value of frictional torque. The roller surface roughness tended to be lower at a position of higher absolute value of specific sliding.

Bulk Temperature Rise of Working Tooth Flanks in Spur Gears : Vibration, Control Engineering, Engineering for Industry

The bulk temperature rise was studied when a moving heat source with variational heat quantity was applied repeatedly at regular intervals to the surface of an isotropic and homogeneous rectangular shaped body used as a model of a spur gear tooth. The effect of radiation at the inner surface of a boss on the bulk temperature rise is reduced as the distance between the inner surface of the boss and the working tooth flank is increased. The bulk temperature rise is almost inversely proportional to the heat supply interval. The size of the heat supply region and the moving direction of the heat source scarcely affect the bulk temperature rise. in a |νν^-| range of not less than 1000, the bulk temperature rise is not affected by the moving velocity of the heat source, and the approximate bulk temperature rise can be obtained by dividing the temperature rise of the working tooth flank due to a stationary heat source by the number of teeth.

Scoring in Spur Gear Pair : 1st Report, Scoring Temperature in Case of Gear Base Oil

The relation of the scoring occurrence to the temperature and the correlation between the gear test results and the two-cylinder test results were examined with a gear base oil using an IAE type high-speed spur gear test rig. In the mixed lubrication state, a scoring occurrence has intimate relation to the working flank bulk temperature which is not affected markedly by the sliding velocity and the oil-jet direction unlike the maximum contact surface temperature and the integral temperature. The scoring temperature of a spur gear pair can be estimated from the bulk temperatures just before seizures in two-cylinder tests taking the specific slidings and the sliding velocities at the beginning or the end of gear meshing into consideration.

Surface pressure strength and surface damage of non-uniform rotating contact roller.

一般のころがり疲れ試験機ではローラは等速回転するが,本研究においてはローラの接触を歯面の接触状態により近づけるため,偏心歯車機構を試験機に適用し,ローラに不等速回転を与え,滑り率が0~-125%で連続的に変化するようにして,調質および高周波焼入れ鋼ローラの面圧強さと表面損傷に関する基礎実験を行った.それぞれのローラの寿命が明らかにされ,表面あらさの変化,表面損傷が滑り率との関連において検討された.

Surface Durability and Surface Failure of Rolling Contact Roller Rotated at Non-uniform Velocity

In the case of a common rolling contact fatigue testing machine, the roller is rotated at uniform velocity. In this research the roller was rotated at non-uniform velocity by applying an eccentric gear mechanism to the machine in order to bring about a contact condition of rollers close to that of gears. Specific sliding of the roller was so adjusted as to change continuously from 0 % to -125 % during one rotation. Under this condition the rolling contact fatigue tests were performed using thermally refined and induction-hardened steel rollers. The roughness change of the roller and the surface failure were discussed in relation to the specific sliding.

Study on the Scoring Resistance of Lubricating Oil in Four Ball Test : 4th Report, Relation between the Scoring Resistance and the Maximum Contact Surface Temperature

In this paper, for two kinds of non-EP mineral oils, the effects of lubricating method, operating time and sliding velocity on initial seizure load were examined by step-load method using a Shell type Four Ball Machine, and the relation between the thermal strength of boundary lubricating film and the maximum contact surface temperature was clarified. The results obtained are summarized as follows : (1) There is only a negligible difference in maximum contact surface temperature (Tcmax)s at scoring between the results in 5 seconds test and the results in 300 seconds test. (2) Without regard to lubricating method and operating time, (Tcmax)s increases with an increase in sliding velocity, and in the sliding velocity range higher than 35 or 46 cm/s, (Tcmax)s is nearly constant. (3) In 300 seconds test, a bulk temperature rise in steel balls has great effect on (Tcmax)s.