Research On Application Software For Servo Drive BHF Control System

The blank holder force is an important control parameter in sheet metal forming field.In deep drawing process, when the blank holder force goes too large, the sheet is easy to crack; else when the force is too small, the sheet easily wrinkling. The BHF is variable in deep drawing process. By applying the numerical control technology in sheet metal forming process, the BHF can be changed accurately along with drawing stroke, according to the NC code.According to the control principle of the servo drive blank holder force, the mathematical model of the relationship between input and output of the system is established. The input of the system is determined by the given output curve,system stiffness, transmission and actuator.By using the finite element software, the stiffness characteristic curve of the mechanism is given, and the influence of different position on the stiffness of the mechanism is analyzed.Based on the open numerical control system platform of “PC+motion control card”,the servo drive blank holder force control application software system is studied.and using the modular design idea, the NC code decoding module, the parameter setting module, the manual control module, the state real-time display module and the database collection module are developed.And the friendly interface is designed by VC++6.0.With the function of the motion controller, the corresponding real-time motion planning is completed and the corresponding motion commands are issued to the driver.Based on the principle of equal error,the mathematical treatment method of linear approximation of function curve is given. And the NC code programming software of the blank holder force control system was designed, which realized the automatic generation from the output curve to the NC code.Then the variable blank holder force loading experiment is completed on the upright constructive mold to test the application software.The results show that the programming software can realize the variable blank holder force loading.