| Because of its high efficiency, low cost and wide adaptability,hyperbaric MIG welding is the main development direction of underwater welding such as marine structures and nuclear reactor components. The arc sound signal is one of the MIG welding process information source, contains a lot of welding information, which can serve as a means to analysis of welding arc state, droplet transition and stability of welding process. During researching on the effect of high pressure environment of droplet transition state of MIG and the realization process of laser enhanced secondary droplet transfer by laser, the hyperbaric MIG welding arc sound signal produced during the experiment process was studied, using synchronous acquisition of current, voltage, arc sound signal and high-speed camera image data, different environmental pressures on the droplet transfer and arc stability and its influence on the welding arc sound on the performance were analyzed, and then introduced to the study of the relationship between before and after laser enhanced adjuvant effect of arc sound characteristics and welding arc welding, droplet transition and stability etc.Welding process for the realization of synchronous sampling signal, synchronous acquisition system using the MIG signal, underwater welding experiments of multi signal synchronous acquisition system of laser provides the integration of arc sound enhancement, the current, voltage, arc sound and high speed video data acquisition, the test results show that the system has high speed synchronous sampling signal function, meet the requirements of the subject, and has a good inhibitory effect on the interference signal in welding process.According to the characteristics of arc sound signal was susceptible to external noise interference, using a variety of hardware and the noise reduction method was used to de noise the software filtering and wavelet denoising techniques, test results showd that the noise reduction was to eliminate the noise signal of arc sound signal in the welding process, which laid the foundation for the welding characteristics of arc sound signal extraction. In order to ensure the accuracy of arc sound signal acquisition, and lay the foundation for the application of arc acoustic testing technology in underwater pressure environment, analyzes the influence of underwater ambient pressure on the sensitivity of microphone and microphone sensitivity at different ambient pressures were calibrated correction, to ensure the accuracy of acoustic signal acquisition, the integrity of the arc.On the basis of the research on the relationship between the welding process welding arc sound in different environment and under pressure, and extract the arc sound signal in time domain and frequency domain characteristics corresponding to the different environment, different droplet transfer mode. Analysis of the mechanism of hyperbaric MIG welding arc sound produced by laser induced acoustic signals as well as the influence of arc sound signal.On the basis of the above work, the 0.1MPa~0.7MPa environment under the pressure of the laser welding droplet transfer control experiments of MIG enhanced, and extract the characteristics of arc sound signal. To analyze and evaluate the stability and droplet transition state by using welding arc sound signal, results show that the enhanced MIG process of laser welding droplet transition state is monitored by use of arc sound, and predict the stability of welding process, has laid the foundation for the high pressure environment of laser enhanced closed-loop control of droplet transfer in MIG welding.Topic related research can enrich the hyperbaric dry underwater welding process of MIG detection methods, MIG for underwater welding droplet transfer and provides a new way of online monitoring of laser welding process stability is enhanced, with a certain application value in science and engineering. |
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