An adaptive tool compensation adjustment method for large shell NC milling process

In this paper, a new adaptive tool compensation adjustment method is proposed based on Siemens 840D numerical control system and digital indicator gauge to solve the problem that the depth dimension of large metal shell is easy to deform when milling with internal and external features of CNC gantry machine. Firstly, in the preparation stage, the machining tool path and measuring tool path are compiled by using the NX software CAM module. The macro program of tool compensation adjustment and the macro program of measuring point are added to the start event of the tool path to make the quick preparation of the machining program and the measurement program. Secondly, in the product deformation detection stage, a software of feature deformation detection based on digital indicator is developed, which the data of measurement points is acquired and is wrote into the CNC system based on measurement program. Thirdly, in the process stage, the R register cutter compensation value adjustment is automatically called by the processing program to realize the multi-feature adaptive compensation processing of deformed products. Finally, the box shape features, step hole and blind holes of big metal shell are processed by using this method. After milling, the depth of the box shape features are 30.1~30.05 mm, the depth of the step holes are 5.98~6.03 mm.