换向持续时间和换向点位置对往复运动齿轮齿条弹流润滑的影响

Reversing time of duration and dead center position effects on the elastohydrodynamic lubrication of reciprocating spur gear rack

往复运动齿轮齿条的润滑失效通常发生在换向死点位置附近,因此研究齿轮齿条换向点位置和换向持续时间对换向过程中润滑油膜的影响具有重要的实际意义。根据齿轮齿条换向瞬间的运动几何关系,建立了换向过程齿轮齿条弹流润滑的瞬态数值模型。采用Ree-Eyring润滑流体,应用多重网格法和多重网格积分法等数值方法,计算得到了齿轮齿条往复运动过程中换向点位置附近一对啮合轮齿间的压力、膜厚和温度,并与前人的实验结果进行了对比验证。分析了不同换向持续时间和换向点位置对一对啮合轮齿间压力、膜厚和温度的影响。齿轮齿条换向过程中油膜厚度明显降低,缩短换向持续时间虽然可以增大齿轮齿条的润滑膜厚,但会导致瞬间油温升高,因此换向持续时间存在最优值。通过比较不同换向死点位置的膜厚发现,当换向死点在单齿啮合后的双齿啮合区时,啮合轮齿间具有较理想的润滑膜厚。无论换向持续时间长短,润滑膜厚的最小值都在换向死点位置,换向死点位置是往复运动齿轮齿条润滑失效的危险点.研究结果为往复运动齿轮齿条的润滑设计提供了理论依据.

Reciprocating spur gear rack is prone to lubrication failure near the reversing dead center position.Therefore,it is of great practical significance to analyze the reversing time duration and dead center position effects on the lubricant film.According to the geometric relationship between the spur gear rack,the transient numerical model of the elastohydrodynamic lubrication(EHL)spur gear rack in the reversing process is established.Using Ree-Eyring lubrication fluid,the numerical techniques such as multigrid method and multigrid integral method were used to calculate the pressure profile,film thickness and oil temperature rise between a pair of meshing gear teeth near the reversing point compared with previous experimental results.The effects of different reversing time durations and dead center positions on the pressure profile,film thickness and oil temperature rise were analyzed.The results show that,the thickness of the film during the gear reversing process is significantly reduced.While shortening the reversing time of duration can improve the lubricating film thickness of the spur gear rack,it causes the instantaneous oil temperature to rise.Therefore,the reversing time duration should have an optimal value.By comparing the film thickness at different reversing dead centers,it is found that when the reversing dead center is in the double-tooth meshing area after single-tooth meshing,the meshing gear teeth have the ideal lubrication film thickness.No matter what the reversing time duration change,the minimum lubrication film thickness is in the reversing dead center position,and the reversing dead center position is the dangerous point of the reciprocating spur gear rack lubrication failure.The results provide a theoretical basis for the lubrication design of reciprocating spur gear rack.