鉄道車両用車軸軸受の内輪と後ぶたの接触部におけるフレツチング摩耗防止に対するセグメント構造CrN膜の適用検討

摘要

鉄道車両用車軸軸受の内輪と後ぶたの接触部に発生するフレツチング摩耗を防止するために.セグメント構造CrN膜で内輪との接触面を被覆した後ぶたを用いて車軸軸受の台上回転試験を実施した.その結果，後ぶた接触面をセグメント構造CrN膜で被覆しても，フレツチング摩耗防止に対する効果は小さいことがわかった.これは，セグメント間の溝部分にCrN膜が形成されて，連続膜になったためと推定される.すなわち，車軸の回転曲げに伴って後ぶたが変形すると，セグメント間の溝部分に形成されたCrNの連続膜は変形に追従できずにき裂を発生してはく離するために.フレツチング摩耗が生じたと考えられる.このことから，セグメント間の溝部分にCrN膜が形成されない方法を確立することができれば，車軸軸受のフレツチング摩耗を防止できる可能性があると考えられる.%Axle journal bearings composed of an inner ring, a backing ring, etc. are used in railway applications. The axle bearings often show fretting wear due to slight relative slip between the inner ring and the backing ring. In this work, the authors have investigated the effects of segment-structured chromium nitride (CrN) film coated on the backing ring on the fretting wear. A rotation test using a full-scale railway axle bearing with a backing ring of a side face which is coated with the segment-structured CrN was conducted. As a result, the segment-structured CrN film had little effect on fretting wear prevention. This is presumably because the CrN film was formed in the groove between the segments. Therefore, when the bacKing ring was deformed due to the rotary bending of the axle, some cracks and decohesion occurred in the CrN film because the CrN film formea in the groove between the segments was not able to follow the deformation. It is conceivable that the fretting wear of the axle journal bearing can be prevented if it is possible to establish a method in which the CrN film is not formed in the groove between the segments.