The Development Of Resistance Spot Welding Quality Online Detection System Based On STM32

Resistance spot welding process has its own advantages, such as energy concentration, small deformation and high efficiency. It is easily used in automated production and does not need to add welding material in the process of welding. It is especially suitable for thin-wall parts. But the quality of resistance spot welding is easily affected by many external factors. Welding quality is not stable, which restricts the application of spot welding technology. Therefore, it is very significant to design a resistance spot welding quality detection system, and it should be online, reliable, non-destructive and low cost.This paper has developed a system based on the single chip processor, whose purpose is to predict the quality of solder joint. Embedded development technology was used, and signal isolation was also taken into consideration. Its duty is to collect welding current, electrode pressure, voltage between electrodes, and electrode displacement signal of the welding process. The characteristics of signal in time domain are input to the expert system. The system will offer a real-time evaluation about the quality of solder joint after reasoning. Main works of this paper are as follows:(1) A resistance spot welding quality monitoring and evaluation system was developed based on the STM32F103VE 32-bit MCU. It has a lot advantages, such as small size, low cost, easy use. It can rapidly and accurately classify Solder joints on-line.(2) The relationship between the welding current, electrode pressure, electrodes voltage and solder joint state was obtained after spot welding test. The specimens were made by 10#. And its thickness was 0.8mm. The relationship between welding current and the solder joint tensile strength was obtained after testing tensile test. So did the splash and tensile strength. The specimens were from spot welding test.(3) In order to verify the accuracy of the system, there are 80 solder joints been broken. They were made by 10 # steel plate using various process parameters. The thickness of specimens was 0.8mm. Comparing the results of the shear strength of solder joints, there are 4 misjudgments which were given by the system. The accuracy of the system on the 10 # steel plate is 95%, which thickness is 0.8mm.