Study On Servo Pressure Control Of Spot And Projection Welding

The electrode pressure welding parameters for one of the most important pointprojection welding in the welding process, point projection welding, stable and dynamicfeedback regulation of the electrode pressure, plays an important role in quality assurancepoint projection welded joints. However, people often only pay attention to the research ofwelding current and welding time, while ignoring the in-depth study of dynamic electrodepressure regulation. The main direction of this topic is the use of servo gun for the pressureon the spot welding control, study pressure curve for spot and projection welding ofdifferent welding processes, real-time adjustment of pressure spot and projection weldingprocess, researching the effect of the pressure to increasing the strength and quality of spotwelding joints. In order to realize the function of spot welding of servo pressure system,this project is to design a set of servo pressure control system based on PLC, and usingmounted on the electrode rod NS-TH3A accurate weighing acquisition and feedbacksensor parameters on the welding.The beginning is processing and installation design, the mechanical structure ofservo pressure, then the servo pressure electrical and power component agencies wereselected, including the servo motor, servo driver, ball screw, PLC controller, weighingmodule, model selection of weighing sensor. Combined with the related electricalcomponents and electrical principle draws electrical diagram and electrical connectionsbetween components. Combined with the characteristics of spot welding system, PLCcontroller, driver, servo pressure control system is developed, and the correspondingprogram is designed. Touch screen to achieve the PLC controller and the welding powersystem communication using HMI, design the interface and the corresponding program ofhuman-computer interaction. In the mechanical design and electrical design andinstallation is completed, the system models the overall debugging. Debugging resultsshow that, HMI according to the predetermined requirements to achieve human-computerinteraction; servo pressure system according to the preset electrode displacement trajectories and electrode pressure curve, and matched with the welding power supplycontrol system good timing; and the pressure sensor and the weighing module realizes thereal-time feedback regulation function.Finally, aiming at the auto parts manufacturing in small diameter (M4, M6)projection welding nut and plate, discusses the application characteristics of projectionwelding process and welding joint forming principle and points (convex) basic structure ofinverter welding machine, analysis of main process parameters on convex welding jointquality influence. On the basis of experiment, according to spot welding servo pressurecurve established system for M4and M6size nut is welded, optimal welding processparameters M4, M6size nut was determined, and verify the process parameters. Theexperimental results show that the M4nut, welding, welding current is9.0KA, the weldingtime is80ms, the electrode when the pressure is3KN, M6nut convex welding, weldingcurrent is9.5KA, the welding time is90ms, the electrode pressure is3.5KN and the use ofsaddle shaped curve of pressure, the joint strength can meet the production requirements,reasonable process stability, at the same time, basically solved the nut convex weldingdeformation problems, experiments show that, large welding current and welding time istoo long will lead to a decline in the quality of the joint.