發(fā)布時(shí)間：2018-05-20 01:15

  本文選題：磁控焊接 + 勵磁電源　； 參考：《南昌航空大學(xué)》2017年碩士論文

【摘要】：磁控焊接技術(shù)是近年來逐漸完善起來的一種新型焊接技術(shù),通過勵磁電源產(chǎn)生的外加磁場可以改變焊接電弧、熔池的形態(tài)以及熔滴過渡等,能有效地細(xì)化焊縫晶粒,減少化學(xué)成分不均勻性,降低結(jié)晶裂紋和氣孔的敏感性,從而提高焊接接頭的力學(xué)性能,改善焊縫質(zhì)量。施加不同的外加磁場,是磁控焊接技術(shù)的關(guān)鍵,因此,研制一種新型的外加交變間歇磁場發(fā)生電源,并將其應(yīng)用于TIG焊接,為磁控焊接技術(shù)的研究提供一些理論依據(jù),對磁控焊接技術(shù)的發(fā)展具有一定的理論意義與實(shí)際價(jià)值。本文研制了一種新型的能產(chǎn)生交變間歇方波的勵磁電源,該電源采用鍵盤輸入?yún)��?shù)的方式調(diào)節(jié)交變頻率及占空比,參數(shù)調(diào)節(jié)直觀方便。電源由主電路、控制電路、放大驅(qū)動電路以及逆變電路組成,對電路的組成結(jié)構(gòu)進(jìn)行了設(shè)計(jì),并對各電路的工作原理進(jìn)行了詳細(xì)的分析。主電路由變壓器、整流器、穩(wěn)壓器等組成,將交流電降壓整流為穩(wěn)定的直流電。控制電路中,由單片機(jī)作為主控芯片產(chǎn)生數(shù)字交變間歇脈沖方波信號,并采用鍵盤輸入?yún)��?shù)的方式,調(diào)節(jié)電源的交變頻率及占空比�？刂齐娐返某绦蛲ㄟ^軟件編程來實(shí)現(xiàn),對軟件編程的四個(gè)方面(主程序、鍵盤輸入程序、交變間歇方波產(chǎn)生程序以及液晶顯示輸出程序)進(jìn)行了設(shè)計(jì)。放大驅(qū)動電路以L298N驅(qū)動芯片為核心,將單片機(jī)產(chǎn)生的交變間歇方波信號進(jìn)行功率放大。通過對比分析幾種逆變電路的結(jié)構(gòu),選擇了全橋式的逆變形式作為該電源的逆變電路。對電源研制過程中遇到的問題提出了解決的方法。結(jié)果表明:研制的電源能穩(wěn)定地輸出交變間歇方波,電源的頻率、占空比、電壓及電流幅值均可調(diào)節(jié),電源的設(shè)計(jì)結(jié)構(gòu)合理,性能基本滿足磁控焊接的要求。利用該電源產(chǎn)生的交變間歇磁場作用于低碳鋼TIG焊接過程,探索有外加交變間歇磁場及交變間歇磁場的交變頻率對焊接電弧的形態(tài)以及焊縫熔寬、熔深的影響,并對磁場作用于焊接的機(jī)理進(jìn)行了探討。試驗(yàn)結(jié)果表明有外加交變間歇磁場作用TIG焊接過程時(shí),焊縫熔寬明顯增加,熔深明顯減小,電弧上部收縮,下部擴(kuò)張,形態(tài)變?yōu)殓娬中?且隨著交變頻率的增大,焊縫熔寬逐漸減小,熔深逐漸增大,電弧發(fā)生收縮的現(xiàn)象。
[Abstract]:Magnetic controlled welding (MAW) is a new welding technology which has been gradually improved in recent years. The welding arc, the shape of molten pool and the droplet transfer can be changed by the external magnetic field generated by the excitation power source, which can effectively refine the weld grain. The mechanical properties and weld quality of welded joints can be improved by reducing the chemical inhomogeneity and reducing the sensitivity of crystal cracks and pores. Applying different applied magnetic fields is the key of magnetically controlled welding technology. Therefore, a new type of applied alternating intermittent magnetic field generator is developed and applied to TIG welding, which provides some theoretical basis for the research of magnetically controlled welding technology. It has certain theoretical significance and practical value for the development of magnetic controlled welding technology. In this paper, a new type of excitation power supply which can produce alternating intermittent square waves is developed. The input parameters of the keyboard are used to adjust the alternating frequency and duty cycle, and the adjustment of parameters is intuitionistic and convenient. The power supply consists of main circuit, control circuit, amplifier drive circuit and inverter circuit. The structure of the circuit is designed, and the working principle of each circuit is analyzed in detail. The main circuit is composed of transformer, rectifier, regulator and so on. In the control circuit, the digital alternating intermittent pulse square wave signal is generated by the single chip microcomputer as the main control chip, and the frequency and duty cycle of the power supply are adjusted by keyboard input parameters. The program of control circuit is realized by software programming. Four aspects of software programming (main program, keyboard input program, alternating batch square wave generation program and LCD output program) are designed. L298N driving chip is the core of the amplifier drive circuit, which amplifies the alternating intermittent square wave signal generated by single chip microcomputer. By comparing and analyzing the structure of several inverter circuits, the full-bridge inverter is chosen as the inverter circuit of the power supply. The solutions to the problems encountered in the development of power supply are put forward. The results show that the power supply can output the alternating intermittent square wave stably, the frequency, duty cycle, voltage and current amplitude can be adjusted, the design structure of the power supply is reasonable, and the performance basically meets the requirements of magnetically controlled welding. The alternating intermittent magnetic field produced by this power supply is applied to the TIG welding process of low carbon steel. The effects of the alternating frequency of the applied intermittent magnetic field and alternating intermittent magnetic field on the shape of welding arc and the weld width and penetration are explored. The mechanism of magnetic field acting on welding is also discussed. The experimental results show that the weld width increases obviously, the penetration depth decreases obviously, the upper arc shrinks, the lower part expands, and the shape becomes bell-shaped with the increase of alternating frequency. The weld width decreases gradually, the penetration increases and the arc shrinks.
【學(xué)位授予單位】：南昌航空大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG444.74

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