Key Technology Of Large Gantry Milling Machine Upgrading

The thirteen meters NC gantry milling machine is a large machine tool, imported from Germany by North Heavy Industry Group Co.,Ltd. in1980s. The machine tool has the characteristics of high precision, so it has produced a lot of precision parts of national scientific research project. Accuracy is decreased and control system is ageing, so the machine tool have been unable to achieve requirement of machining. Although some mechanical parts wear, stress of components on the machine tool has been released in years, and performance of the machine is very stable, the machine upgrading is valuable. Based on these conditions, the NC system of the gantry milling machine is upgraded and accuracy of the gantry machine is recovered.(1) A program of control system upgrading and mechanical repair is made, and type of CNC system is chosen, according to the inspection results of the machine tool.(2) The parameter of control is analyzed and adjusted according to the curve of frequency response. Finally, the dynamic response of the drive system is improved and the fitting parameter of servo-control system is acquired.(3) Automatic cross-rail compensation program is designed, and the level accuracy of the cross-rail is ensured.(4) Using laser interferometer to detect the positioning accuracy of machine tool, the error of accuracy is compensated, the performance of machine tool is improved.Through a series of upgrades and debug, the stick-slip phenomenon is eliminated, which provides experience for the future to solve the stick-slip of machine tool. The mechanical accuracy of the machine tool had been improved, the machining of machine tool is stable, and achieved accuracy of the gantry milling machine is realized.