【摘要】：采用焊劑帶約束電弧超窄間隙焊接方法焊接中厚板,具有生產(chǎn)效率高、熱輸入低的特點,能夠降低焊后殘余變形和殘余應(yīng)力,具有一定的應(yīng)用前景。然而,焊劑帶的制作效率低且容易破損,嚴重阻礙了超窄間隙焊接方法在工業(yè)方面的推廣和應(yīng)用。為解決上述問題,課題組研制了焊劑片和玻璃纖維網(wǎng),依靠玻璃纖維網(wǎng)與焊劑片粘接形成焊劑片鏈替換焊劑帶,達到了在坡口內(nèi)對焊接電弧的穩(wěn)定約束,并對前期超窄間隙焊槍存在的缺點進一步改進。針對前期超窄間隙焊槍存在槍體支撐剛度不夠,結(jié)構(gòu)復(fù)雜的問題,設(shè)計了兩款專用焊槍,第一種焊槍由銅質(zhì)導(dǎo)電板和鋼制支撐板組成以提高焊槍整體剛度,槍頭金屬罩內(nèi)填充云母片使其與導(dǎo)電嘴和支撐板絕緣,焊絲通過導(dǎo)電嘴和陶瓷壓緊塊中間位置時,依靠導(dǎo)電嘴和陶瓷壓緊塊之間的夾緊力使焊絲與導(dǎo)電嘴緊密接觸保證導(dǎo)電性。但在試驗過程中,導(dǎo)電嘴會因電弧攀升燒損后不易更換。為此設(shè)計了第二種焊槍,該焊槍制作材料選用黃銅,整體結(jié)構(gòu)由上擰螺母、夾絲螺母、槍體三部分構(gòu)成,上擰螺母保證焊槍與焊機槍柄的固定及焊槍良好導(dǎo)電性,夾絲螺母保證焊絲輸送過程與導(dǎo)電嘴始終接觸可靠。試驗證明,該焊槍解決了第一種焊槍的缺點,能夠滿足中厚板超窄間隙的焊接。針對焊劑帶存在的問題,設(shè)計了兩種焊劑片結(jié)構(gòu)和編制了玻璃纖維網(wǎng)。第一種焊劑片結(jié)構(gòu)為矩形,第二種結(jié)構(gòu)為帶圓形小缺口的矩形,試驗中發(fā)現(xiàn),第一種焊劑片與玻璃纖維網(wǎng)粘接的焊劑片鏈對坡口內(nèi)焊縫的高低變化適應(yīng)性差,不利于進行填充、蓋面焊接,而第二種缺口型焊劑片制作的焊劑片鏈能夠很好適應(yīng)。玻璃纖維網(wǎng)是將玻璃纖維繩的四條經(jīng)線與一條緯線交叉纏繞編制的網(wǎng)狀物,并在經(jīng)緯線交叉處和緯線處涂覆稀釋的玻璃纖維浸潤劑,促使固化后的玻璃纖維網(wǎng)能夠具有一定的剛度,與焊劑片粘接成焊劑片鏈對折放入坡口內(nèi),能夠依靠其自身的回彈力使焊劑片與坡口側(cè)壁緊密接觸約束電弧。采用焊劑片鏈約束電弧超窄間隙焊接方法對中厚板Q235A根焊縫的單面焊雙面成形影響因素分析得出:焊接電壓主要決定坡口側(cè)壁融合,焊接電流決定著根焊縫背部成形,在匹配的工藝參數(shù)下,能夠?qū)崿F(xiàn)根焊縫單面焊雙面成形。與常規(guī)焊接方法相比,利用焊劑片鏈對電弧產(chǎn)生約束焊接中厚板X70管線鋼具有一定的優(yōu)勢。焊接過程熱輸入小,得到的焊接接頭熱影響區(qū)寬度窄,焊縫區(qū)主要為針狀鐵素體組織,熱影響區(qū)主要為多邊形鐵素體組織和貝氏體組織,粗晶區(qū)沒有產(chǎn)生軟化且硬度高于母材,焊縫區(qū)和熱影響區(qū)的沖擊韌性均較好。
[Abstract]:The welding of medium and thick plate by flux strip confined arc ultra-narrow gap welding has the characteristics of high production efficiency and low heat input. It can reduce the residual deformation and residual stress after welding and has a certain application prospect. However, the manufacturing efficiency of flux strip is low and easy to break, which seriously hinders the application of ultra-narrow gap welding method in industry. In order to solve the above problems, the flux sheet and glass fiber mesh were developed, and the flux chain was replaced by the glass fiber mesh bonding to the flux sheet, which achieved the stable restraint of welding arc in the groove. The shortcomings of the super narrow gap welding torch are further improved. Aiming at the problem of insufficient support stiffness and complex structure of the super narrow gap welding torch, two special welding guns are designed. The first kind of welding torch is composed of copper conductive plate and steel support plate to improve the overall stiffness of the welding torch. The metal cover of the gun is filled with mica to insulate it from the conductive nozzle and the supporting plate. When the wire passes through the middle position of the conductive nozzle and the ceramic compaction block, the wire and the conductive nozzle are in close contact with each other to ensure the electrical conductivity by relying on the clamping force between the conductive nozzle and the ceramic compaction block. However, in the course of the test, the conductive nozzle will not be easily replaced after the arc has climbed and burned. For this reason, a second welding torch is designed. The welding torch is made of brass. The whole structure consists of three parts: the upper screw nut, the clamp nut, and the gun body. The upper screw nut ensures the fixing of the welding torch and the gun handle of the welder and the good conductivity of the welding torch. The wire-clamped nut ensures that the welding wire conveying process is always in contact with the conductive nozzle. The test results show that the welding torch solves the shortcoming of the first kind of welding torch and can meet the welding of ultra-narrow gap of medium and thick plate. Aiming at the problems of flux strip, two kinds of flux sheet structure and glass fiber mesh were designed. The first kind of flux sheet is rectangular and the second one is rectangular with circular and small notches. It is found in the experiment that the flux chain bonded with glass fiber mesh has poor adaptability to the variation of weld seam in the groove, which is not conducive to filling. The cover surface is welded, and the flux chain made of the second notched flux sheet can be well adapted. A glass fiber mesh is a net that intertwines four longitudes of a glass fiber rope with a weft line and is coated with a dilute glass-fiber soakage at the crossing and the weft line. The cured glass fiber mesh can have a certain rigidity, the flux chain is folded and put into the groove by bonding with the flux sheet, and the flux sheet is in close contact with the side wall of the groove to restrain the arc by its own resilience. By using flux chain confined arc ultra-narrow gap welding method, the influencing factors of one-sided welding and double-sided forming of Q235A weld of medium and thick plate are analyzed. The results show that the welding voltage mainly determines the fusion of the side wall of the groove, and the welding current determines the forming of the back of the root weld. Under the matching process parameters, single side welding and double side forming of root weld can be realized. Compared with the conventional welding method, the flux chain has a certain advantage in arc constrained welding of X70 pipeline steel. The weld zone is mainly acicular ferrite structure, the heat affected zone is polygonal ferrite structure and bainite structure, and the coarse grain zone does not soften and hardness is higher than base metal, but the heat input is small, the width of heat affected zone is narrow, the weld zone is mainly acicular ferrite structure, and the heat affected zone is polygonal ferrite structure and bainite structure. The impact toughness of weld zone and heat affected zone are good.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG444

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