Research And Implement Of Constant Load Control System In NC Machining

Precision and efficiency are the aim that is pursued forever in manufacturing. In NC machining process force deformation error is produced because of fluctuating of cutting load, which lead to inhomogeneous deformation that cause machining error of finished surface. That is one of the main sources of machining error of NC machine tools. Keeping cutting load constant in machining process is the most effective means that can reduce the force deformation error.Firstly, the source, buildup and character of cutting load in NC machining process were analyzed in this thesis. The current signal was analyzed and processed with the method that detects cutting load in NC processing indirectly through the current of basic shaft of NC machine tools, and cutting load characteristic value was extracted. The mapping relation model between cutting load and machining parameters was set up and the model parameters were fitted with least squares techniques. Base on that a model based control program and the constant load control algorithm was present. According to the control program and control strategy a constant load control system was designed that can enhance the machining precision while enhancing machining efficiency. That has great application value in production.The system consists of two parts such as hardware and software, in which the software accomplished data collection and analyzing, control algorithm executing, adjusting manufacturing parameters online, and keeping cutting load constant in a certain extent. Finally, the validity of the system was justified in sides of precise and efficiency through two experiments. The technique has been replanted to the item of NC seven axes five-linkage vertical combination machine and expected to accomplish the manufacturing of big screw propeller.