锯链传动片疲劳试验失效分析

国产锯链在高速空载疲劳试验时出现早期损坏，其寿命比同型号的OREGON锯链短很多。通过化学成分、金相组织、表面硬度及零件制造精度的检测对比分析，认为这是由于国产锯链传动片、连接片和切齿片的制造精度不高，实际孔距尺寸偏大，使得锯链节距大于链轮分度圆节距。这时锯链与链轮的相互位置关系就无法保证，锯链与链轮的啮合状况变坏，传动过程中将产生冲击、滑移窜动、爬高、张力波动等现象，使锯链的负荷成倍增加，尤其是传动片清理齿齿尖部位承受长期反复的冲击载荷，从而导致早期疲劳断裂。提高零件制造精度后，锯链与链轮的啮合状况正常，高速空载疲劳试验寿命达到要求。

Failure Analysis on Chainsaw Chain Link Fatigue Test

Early failures of a domestically manufactured chain for a chainsaw during a high-speed-no-load duration test were seen when compared with its imported counterpart under the brand name of OREGON. A series of inspections of chemical eomposition, micro-structure, surface hardness and manufacturing tolerances had been conducted and the results showed the main reason for this was the lack of control in manufacturing tolerances of the components of the chain resulting an excessive distance between the rivet holes i. e. a mismatch of the pitch of the chain and that of the sprocket, therefore the relative location between them in operation was destroyed and an adverse working condition resulted. Incurred impacts, slippages, climbouts and fluetuations in tension increased the working load of the chain to many folds and continual impact load to the sprocket engageable drive tang of the chain link lead to its early failure. After the improvement in tolerances, a better working condition of the sprocket and the chain extends the duration of the chain to a satisfactory level were shown by another high-speed-no-load duration test.