在本論文之實驗中,我們針對給油週期對摩擦係數、接觸電阻等條件參數,並藉由與業界共同合作開發的肘節式曲手軸磨耗試驗機來進行研究。本論文是以現有的曲手軸磨耗試驗機加裝可調整給油量與給油時間的自動給油系統,以模擬射出機實際狀況的給油情形以及油膜變化之情形。將給油週期和不同材質的曲手軸搭配在一起,更能發現到3種不同材質的曲手軸之油膜變化。從實驗結果可以看出,當負荷5000 kgf、4或8 rpm、使用銅布司曲手軸套,運轉2500 cycles時注入油脂6 c.c.前後的正轉時之最高摩擦係數降低約24%之摩擦係數。使用鉻鉬鋼曲手軸套在運轉2500 cycles時注入油脂6 c.c.,降低摩擦係數之效果相當明顯。在試驗3小時之後,表面接觸電阻值略有上升,而摩擦係數有些許的降低,顯示新潤滑油脂的磨合期大約在3小時,這可能是因為荷重更重,使得兩滑動面之間磨合的更快;當荷重越重時,表面接觸電阻值就會越低,20,000公斤重以上的荷重,對於二滑動接觸面而言,已是一相當大的荷重,相對的油膜厚度也將會小很多,對潤滑而言,是較為不利的狀況。因此,在曲手軸承設計上,軸承面壓盡量以不超過每平方公分770 kgf為原則。
In this research, we study the effect of grease change period on the friction coefficient and electrical contact resistance (ECR). We used the toggle pin wear tester to conduct the tests. We used 3 different toggle pin materials to see the differences among them. Results shows that the friction coefficient decreased obviously for about 24% after replenishing 6 c.c. of grease to the toggle pin after 2500 cycles during testing under 5000 kgf of test load and 4 or 8 rpm of test speed. From the variation of the ECR and friction coefficient, it showed that a heavier load would make the running-in time shorter. The ECR value would decrease with increasing load. It shows that the contact pressure should be less than 770 kgf/cm2.