Case-hardened Steel Rollers Research Articles

Influence of Compressive Residual Stress Induced by Peening on Contact Fatigue Strength of Case-Hardened Steel Roller

Influence of Compressive Residual Stress Induced by Peening on Contact Fatigue Strength of Case-Hardened Steel Roller

Influence of Compressive Residual Stress Distribution Induced by Peening on Rolling Fatigue of Case-Hardened Steel Roller

Influence of Compressive Residual Stress Distribution Induced by Peening on Rolling Fatigue of Case-Hardened Steel Roller

2mmの有効硬化層深さを有する浸炭硬化ローラの疲労寿命

2mmの有効硬化層深さを有する浸炭硬化ローラの疲労寿命

404 ピーニングを施した浸炭硬化ローラの疲労過程における表面性状の変化

404 ピーニングを施した浸炭硬化ローラの疲労過程における表面性状の変化

S112021 同一表面粗さにおける浸炭硬化ローラの疲労寿命に及ぼすキャビテーションピーニングとショットピーニングの影響

S112021 同一表面粗さにおける浸炭硬化ローラの疲労寿命に及ぼすキャビテーションピーニングとショットピーニングの影響

818 微粒子ピーニングを施した浸炭硬化ローラの疲れ寿命(機素潤滑設計III)

818 微粒子ピーニングを施した浸炭硬化ローラの疲れ寿命(機素潤滑設計III)

1213 キャビテーションピーニングを施した鋼歯車の面圧強さ(面圧強度・疲労強度,一般講演)

In order to investigate the effect of cavitation peening on surface durability of steel gears, the case-hardened steel rollers and gears cavitation-peened under different conditions were fatigue-tested using a roller testing machine and a gear testing machine. The hardness and the compressive residual stress of the test rollers and gears were increased by the cavitation peening. On the other hand, their surface roughness was not increased so much. In the roller tests, the fatigue life of all the cavitation-peened rollers was longer than that of the non-peened roller. In the gear tests, the surface durability of the test pinions was improved by the cavitation peening. Judging from the relationships between the maximum stress amplitude and the surface roughness, it was clear that the surface durability of steel gears was improved by the increase in surface hardness due to the cavitation peening with little influence of surface roughness.

101 キャビテーション・ショットレス・ピーニングによる鋼歯車の疲れ強さ向上(OS02-1 歯車の強度I)

In order to investigate the effect of cavitation shotless peening on fatigue strength of steel gears, the case-hardened steel rollers and gears cavitation shotless peened under different conditions were fatigue-tested using a roller testing machine and a gear testing machine. The hardness and the compressive residual stress of the test rollers and gears were increased by cavitation shotless peening. On the other hand, their surface roughness was not increased so much. In the fatigue tests, the fatigue life of most cavitation shotless peened rollers and gears was longer than that of the non-peened roller and gear. In particular, the fatigue life of cavitation shotless peened rollers and gears was significantly improved by using a modified nozzle for a high-speed water jet to obtain a greater peening effect. Therefore, it was found that the cavitation shotless peening is good for the increase in fatigue strength of steel gears.

浸炭硬化焼結鍛造歯車の疲れ強さ(O.S.02-2 歯車の強度(2))

In order to compare the fatigue strength of powder forged gears with that of steel gears, the case-hardened powder forged rollers and gears with different Ni content and the case-hardened steel rollers and gears were fatigue-tested under a sliding-rolling contact condition. The surface hardness of the powder forged rollers and gears with the lower Ni content was almost equal to that of the steel rollers and gears. On the other hand, the hardness of the powder forged rollers and gears with the higher Ni content was smaller than that of the other rollers and gears. The compressive residual stress and the surface roughness of the powder forged rollers and gears were about equal to those of the steel rollers and gears. The failure mode of the test rollers was mainly spalling, and that of the test gears was mainly pitting. Using the relationship between the maximum amplitude of the ratio of stress to Vickers hardness and the fatigue life of the rollers and gears, it was denoted in this experimental range that the fatigue life of the powder forged rollers and gears with the higher Ni content was longer than that of the steel rollers and gears.

816 ショットピーニングされた浸炭硬化鋼ローラの面圧強さに及ぼすショット材の影響

816 ショットピーニングされた浸炭硬化鋼ローラの面圧強さに及ぼすショット材の影響

2510 浸炭硬化鋼ローラのピッチング強さに及ぼすショットピーニングの影響

The purpose of this study is to investigate the influence of shot peening on the pitting strength of case-hardened steel rollers. The hardness, the compressive residual stress and the surface roughness of the rollers increased by the shot peening. The failure mode of the rollers was pitting. The surface durabilities of most shot-peened rollers were higher than that of the unpeened roller in these experiments. Especially, the smaller the surface roughness of the shot-peened rollers was, the higher the surface durabilities of them were. The increase of the surface roughness by the stronger shot peening resulted in the shorter fatigue lives of the shot-peened rollers. Therefore, it could follows from this that the light shot peening should be selected in order to improve the pitting strength of the steel rollers in these experimental range.

1107 浸炭硬化鋼製ローラの面圧強さに及ぼすショットピーニングの影響

1107 浸炭硬化鋼製ローラの面圧強さに及ぼすショットピーニングの影響

213 浸炭硬化鋼製ローラの面圧強さに及ぼすショットピーニングの影響(OS1-4 伝動装置の基礎と応用)

213 浸炭硬化鋼製ローラの面圧強さに及ぼすショットピーニングの影響(OS1-4 伝動装置の基礎と応用)

Effect of Crowning Radius on Rolling Contact Fatigue Strength of Case-Hardened Steel Roller.

This paper deals with the effect of crowning radius on the rolling contact fatigue strength of case-hardened steel roller. Three types of the rollers, which had crowning radii of 30 mm, 15 mm and 7.5 mm, were fatigue-tested under a sliding rolling contact condition. The rolling contact fatigue strength of the roller became higher as the crowning radius became smaller. The failure modes of the rollers with crowning radii of 15 mm and 7.5 mm were pitting and wear, while the failure mode of the roller with a radius of 30 mm was only pitting. The pitted depth of all rollers depended almost on the depth of the maximum amplitude of the ratio of principal shear stress to Vickers hardness. The rolling contact fatigue life of the rollers could be expressed using non-dimensional value pmax/(Λ·Hυ) independent of the crowning radius, where, pmax, and Λ and Hυ are the maximum Hertzian stress, specific film thickness and Vickers hardness, respectively.

Effect of asperity interacting frequency on rolling fatigue (2nd report, The cases for a thermal refined S45C carbon steel, a hardened SCM435 alloy steel and a case-hardened SCM415 alloy steel)

In order to evaluate the severity of asperity interactions in rolling contact, the author introduced a new parameter 'asperity interacting frequency Naf'. Naf is defined by the number of contact positions of higher hardness roller with different microgeometries which are brought into contact with any one position of mating lower hardness roller and the effects on rolling fatigue have been examined using thermal refined or hardened rollers with different hardnesses. As the results, similar to the previous results obtained using normalized steel rollers, it was found that there exists a regular relation between the parameter Naf and the pitting life in pure rolling conditions. Furthermore, it was recognized that the occurrence of micro pitting, which is apt to develop on the surface of a case-hardened steel roller, is decisively affected by the parameter Naf.

Surface durability of case-hardened nickel-chromium steel rollers under pure rolling and sliding-rolling contacts

Rolling contact fatigue tests were performed under sliding-rolling and pure rolling contacts using case-hardened steel rollers with three different case depths as models of gear tooth surfaces to study the surface durability and the optimum design condition of surface-hardened steel gears. The test results in conjunction with the subsurface shear stresses indicated that the relations between the rolling fatigue lives and the maximum amplitudes of the ratio of orthogonal shear stress to Vickers hardness may be used as a measure of surface strength. Using these relations the optimum case depths for surface durability at various relative radii of curvature were calculated for sliding-rolling and pure rolling contacts.

Surface fatigue failure of case-hardened nickel- chromium steel rollers under pure rolling and sliding-rolling contacts

Case-hardened steel rollers with three different case depths were tested under sliding-rolling and pure rolling contact conditions using a rolling contact fatigue testing machine. The morphology of cracks and surface failures was examined. The main spalling cracks initiated beneath roller surfaces were almost parallel to the roller surfaces. The crack initiation depths of the spalls corresponded to the shallower portions of the spall bottoms and not to the maximum depths of the spalls. Spalling cracks initiated in the case and not at the case-core boundary. Shell pattern, fish eye, pore, tongue and striation characteristics of the spall bottom and dimples at the ends of the spalls were observed.

The effect of changing the rolling direction on the rolling contact fatigue lives of annealed and case-hardened steel rollers

The effects of changing the rolling direction and of repeated loading on the rolling contact fatigue lives of annealed 0.45% carbon steel rollers and case-hardened nickel-chromium steel rollers under conditions of sliding rolling contact were studied. The influence of plastic flow in the subsurface layer on the rolling fatigue life was examined. The increase in the rolling fatigue life of an annealed steel roller due to a change in the rolling direction was significant, especially when the rolling direction was changed just before the formation of macroscopic surface cracks and pits. The effect with case-hardened steel rollers was negligible. The varying effects of changing the rolling direction on the rolling fatigue life were due to differences in work-hardening and the extent of plastic flow in the rollers.

Macroscopic and microscopic changes in the surface layers of annealed and case-hardened steel rollers due to rolling contact

Measurements of the residual stress and observations of the microstructure at the surface and in the subsurface of rollers were performed during rolling contact fatigue tests of annealed 0.45% carbon steel and case-hardened nickel-chromium steel rollers. Compressive residual stresses in annealed rollers were induced by the rolling contact. With case-hardened rollers they were induced by heat treatment prior to the rolling contact fatigue tests. After the rolling contact fatigue tests the compressive residual stresses on the surface of the annealed rollers and in the subsurface of the case-hardened rollers relaxed; a characteristic substructure was formed by the stress cycles, which caused surface failure. It was confirmed that the microcracks leading to surface failure initiate on the surfaces of annealed rollers and in the subsurface of case-hardened rollers.