Abstract: A new type of heavy-duty high-precision inertial friction welding machine moving fixture clamping mechanisms was designed to meet the high-precision welding quality requirements of typical parts of aircraft engines. The positioning error analysis of the moving fixture clamping mechanisms was carried out.  A theoretical model was established for the mapping relationship between the positioning component tolerance of a mobile fixture clamping mechanism and the positional error of the welded part, ignoring other influencing factors such as machine tool errors, positioning reference plane errors of welded parts, and errors caused by clamping forces and thermal deformation on the welding accuracy of welded parts, this error theoretical model was used to calculate the dimensional tolerance range of the positioning components of the mobile fixture clamping mechanism based on the required welding accuracy of a certain type of rotor, a mobile fixture clamping mechanism was designed based on the calculated tolerance range of positioning components and clamp the welded parts to complete the welding tests. The experimental results show that the maximum errors of coaxiality error, parallelism error, and axial shortening error are as 0.04 mm, 0.02 mm and 0.12 mm respectively, all error detection results meet the required welding accuracy(coaxiality error:0.06 mm; parallelism error:0.04/300 mm; axial shortening error:± 0.2 mm). It indicates that the tolerance range of each positioning component obtained through analysis is reasonable, and the error theoretical model has important theoretical guidance significance for the tolerance allocation of moving fixture positioning components in the design of heavy-duty inertial friction welding machines.

Key words: mobile fixture, positioning error, error mapping, welding precision, tolerance

摘要： 针对航空发动机典型零件的高精度焊接质量需求，设计了一种新型重型高精度惯性摩擦焊机移动夹具的夹紧机构，对移动夹具进行定位误差分析。建立一种移动夹具定位元件公差与焊件位姿误差映射关系的理论模型，在忽略其他影响因素（如机床误差、焊件的定位基准面误差、夹紧力和热变形引起的误差等）对焊件焊接精度影响的情况下，利用该误差理论模型，根据某型转子要求的焊接精度，通过误差理论模型计算得到移动夹具夹紧机构定位元件的尺寸公差范围，再根据该尺寸公差范围设计移动夹具夹紧机构并夹装焊件，从而完成焊接试验。试验结果显示，同轴度误差、平行度误差和轴向缩短量误差三项误差中的最大误差分别为0.04 mm、0.02 mm和0.12 mm，各项误差检测结果均达到所要求的焊接精度（同轴度误差：0.06 mm；平行度误差：0.04/300 mm；轴向缩短量误差：±0.2 mm），证明计算得到的各定位元件的公差范围合理，所建立的误差理论模型对重型惯性摩擦焊机设计中移动夹具定位元件的公差分配具有重要的理论指导意义。

关键词: 移动夹具, 定位误差, 误差映射, 焊接精度, 公差