發(fā)布時(shí)間：2018-05-24 19:20

  本文選題：超聲振動(dòng) + 電阻釬焊��； 參考：《蘭州理工大學(xué)》2017年碩士論文

【摘要】：電阻釬焊具有熱量集中,加熱時(shí)間短,熱影響區(qū)小,變形和應(yīng)力小的優(yōu)點(diǎn),廣泛應(yīng)用于電子、微型設(shè)備和小型醫(yī)療設(shè)備。文獻(xiàn)報(bào)道,超聲波的施加使電阻釬焊接頭焊合率升高到85%。目前,電阻釬焊仍限于微型材料的焊接,并且對(duì)超聲輔助電阻釬焊原理也沒(méi)有相關(guān)研究。因此,本文以焊接較大尺寸的接頭,探索超聲輔助電阻釬焊原理為主要的研究目標(biāo),設(shè)計(jì)制作了超聲輔助電阻釬焊裝置,采用Al-Si-Mg合金釬料,在大氣環(huán)境下對(duì)6063鋁合金進(jìn)行了超聲輔助電阻釬焊。該裝置結(jié)構(gòu)簡(jiǎn)單,能提供瞬時(shí)低電壓、大電流、精確焊接壓力,減少超聲波衰減,且該裝置為國(guó)內(nèi)首個(gè)超聲輔助電阻釬焊裝置,并獲國(guó)家專利授權(quán)。本文研究了兩步電阻釬焊工藝,并得到了最優(yōu)工藝。研究中發(fā)現(xiàn)電阻釬焊過(guò)程中會(huì)發(fā)生爆破現(xiàn)象,而超聲波可以消除爆破現(xiàn)象,超聲方向和時(shí)間以及焊接接頭幾何形狀會(huì)對(duì)爆破現(xiàn)象有影響。兩步電阻釬焊方法使母材和釬料之間的界面形成了較大區(qū)域的冶金結(jié)合,從而改善了釬料和母材之間的連接條件。研究發(fā)現(xiàn),爆破現(xiàn)象的產(chǎn)生是由于在電、熱和力的作用下熔融釬料中的電流密度過(guò)高引起的。當(dāng)超聲振動(dòng)移除兩母材接觸區(qū)域的氧化膜,并且超聲時(shí)間不低于6s時(shí),可消除爆破現(xiàn)象。本文采用非等尺寸的焊接接頭,研究了接頭中釬料的偏移現(xiàn)象。同時(shí)討論了等尺寸和非等尺寸條件下Si元素的高速擴(kuò)散以及火口裂紋的產(chǎn)生和防止機(jī)制。研究發(fā)現(xiàn):由于上界面處電流密度大,產(chǎn)生的熱量高,而且下界面處的散熱能力強(qiáng),因此,產(chǎn)生了釬料的偏移現(xiàn)象。在焊接電流持續(xù)作用于局部區(qū)域時(shí),熔融釬料中的Si元素偏聚于界面處,并且沿著高擴(kuò)散率通道(Al晶粒的晶界)向母材中高速擴(kuò)散。當(dāng)采用非等尺寸焊接接頭時(shí),Si的高速擴(kuò)散只在電流密度大的區(qū)域產(chǎn)生。最長(zhǎng)的擴(kuò)散距離達(dá)到了958.3μm。在高溫條件下,擴(kuò)散的Si使母材產(chǎn)生了溶蝕孔洞,最后形成了火口裂紋。而超聲振動(dòng)可以防止局部區(qū)域的高溫、Si元素的擴(kuò)散以及溶蝕孔洞和火口裂紋等裂紋的產(chǎn)生。通過(guò)上述的分析,得出了不同接頭尺寸和有無(wú)超聲振動(dòng)條件電阻釬焊機(jī)理,以及電流路徑變化的機(jī)理圖。
[Abstract]:Resistance brazing has the advantages of heat concentration, short heating time, small heat affected zone, small deformation and small stress, so it is widely used in electronic, micro-equipment and small medical equipment. It is reported that the application of ultrasonic wave can increase the soldering rate of resistance brazing joint to 85. At present, resistive brazing is still limited to the welding of micro materials, and the principle of ultrasonic assisted resistance brazing is not studied. Therefore, in order to weld large size joints and explore the principle of ultrasonic assisted resistance brazing, an ultrasonic assisted resistance brazing device is designed and fabricated, and Al-Si-Mg alloy filler metal is used. Ultrasonic assisted resistance brazing of 6063 aluminum alloy was carried out in atmospheric environment. The device is simple in structure, can provide instantaneous low voltage, high current, accurate welding pressure and reduce ultrasonic attenuation. It is the first ultrasonic assisted resistance brazing device in China and has been authorized by national patent. In this paper, the two-step resistance brazing process is studied, and the optimum process is obtained. It is found that blasting will occur in the process of resistance brazing while ultrasonic wave can eliminate the blasting phenomenon. The direction and time of ultrasonic and the geometry of welded joint will affect the blasting phenomenon. The two-step resistance brazing method makes the interface between the base metal and the filler metal form a large area of metallurgical bonding, thus improving the connection condition between the filler metal and the base metal. It is found that the blasting phenomenon is caused by the high current density in the molten solder under the action of electricity, heat and force. When ultrasonic vibration removes the oxide film in the contact area of the two base materials and the ultrasonic time is not less than 6 s, the blasting phenomenon can be eliminated. In this paper, the offset phenomenon of solder in the joint is studied by using non-equal size welded joint. At the same time, the high speed diffusion of Si element and the mechanism of crack generation and prevention are discussed under the condition of equal size and unequal size. It is found that because of the high current density at the upper interface, the high heat production and the strong heat dissipation capacity at the lower interface, the offset phenomenon of solder is produced. When the welding current continues to act on the local region, the Si element in the molten solder concentrates at the interface and diffuses at high speed along the grain boundary of the Al grain in the high diffusivity channel. The high speed diffusion of Si only occurs in the region with high current density when the non-equal size welded joints are used. The longest diffusion distance is 958.3 渭 m. At high temperature, the dispersed Si causes the dissolution of the base metal, and finally forms the crack at the mouth of the fire. The ultrasonic vibration can prevent the diffusion of Si element in the local region and the formation of cracks such as cavity and fire mouth. Through the above analysis, the mechanism of resistance brazing with or without ultrasonic vibration and the mechanism diagram of current path change are obtained.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG457.14

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本文編號(hào)：1930249