插针机构中圆柱凸轮滚子疲劳寿命预测方法

Prediction Method of Fatigue Life of Cylindrical Cam Rollers in Pin Insertion Mechanism

以高速插针机为研究对象,对其插针机构进行力学分析,推导圆柱凸轮沟槽曲面方程,建立凸轮滚子(以下简称滚子)-沟槽的接触力学模型和滚子在沟槽内滚动的运动几何模型。基于赫兹接触理论计算出凸轮转动1圈过程中每一时刻滚子与沟槽受力接触点的最大接触应力。基于Miner线性疲劳累积损伤理论判断滚子圆周方向上的危险点,并以该危险点为对象,实现了对滚子疲劳寿命的定量计算。结合具体算例,分析了滚子直径、凸轮直径、接触长度、凸轮转速对滚子接触疲劳寿命的影响。计算结果表明:对滚子而言,当凸轮滚子直径从10 mm增大到26 mm时疲劳寿命随之增大了14.1倍;当凸轮直径从50 mm增大到140 mm时疲劳寿命随之增大了7.5倍;当接触长度从5 mm增大到15 mm时疲劳寿命随之增大了26.0倍;当凸轮转速从600 r·min^(-1)增大到1300 r·min^(-1)时疲劳寿命随之降低为原来的0.449%。

Taking the high-speed pin insertion machine as the research object,the mechanical analysis of its pin insertion mechanism was carried out,the cylindrical cam groove surface equation was established.The contact mechanics model of the cylindrical cam roller and the groove,and the geometric model of the roller rolling in the groove were established.Based on Hertz contact theory,the maximum contact stress of the contact point between roller and groove was calculated at each moment in the course of the cam rotation.Based on the Miner linear fatigue cumulative damage theory,the dangerous point in the circumferential direction of the roller was judged,and the dangerous point was taken as the object to realize the quantitative calculation of the fatigue life of the roller.Through a specific example,the influence of roller diameter,cam diameter,contact length,and cam rotation speed on the contact fatigue life of the cam roller was illustrated.The calculation results showed that:when the diameter of the cam roller increased from 10 mm to 26 mm,the fatigue life increased by 14.1 times;when the diameter of the cam increased from 50 mm to 140 mm,the fatigue life increased by 7.5 times;when the contact length increased from 5 mm to 15 mm,the fatigue life of the cam roller increased by 26.0 times;when the cam speed increased from 600 r·min^(-1) to 1300 r·min^(-1),the fatigue life decreased to 0.449% of the original.