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 采用高精度的全自动引伸计有助于提高测定冷轧薄板塑性应变比r值的准确度，但在试验中发现其某些机构如果调整不到位，会对结果准确度产生显著影响。通过对配备一种高精度接触式全自动引伸计的国产拉伸试验机测定r值时机械影响因素的分析，总结了其机构调整方法，并与配备其他全自动引伸计的进口拉伸试验机进行了比对试验。两者所测r值结果基本一致,相对误差在±3.0%以内，表明分析和总结的调整方法可有效地保证该试验机测定r值具有较好的稳定性和准确性。

Machine Influencing Factors Analysis on Measurement of Plastic Strain Ratio of Cold Rolled Thin Sheets

Using the complete automatic extensometer with good precision helped to improve the accuracy of determi- nation to the plastic strain ratio of cold rolled thin sheet-r value, but it was found in tests that it had a marked effect on the accuracy of results if the adjustments of its certain mechanisms do not reach right positions. Through analysis of machine influencing factors in the determination of r value by using tensile testing machine made in china which is equipped with an oscillatory complete automatic extensometer with good precision, the redressal method of mecha- nisms was summarized. The comparison test with imported tensile testing machine which is equipped with other complete automatic extensometer was made. Both results of r value are basically consistent, and the relative errors are less than ±3.0 %. This indicates analysis and summarized adjustment method can effectively guarantee good sta- bility and veracity in determination of r value by this tensile testing machine.