焊剂片链约束电弧中厚板超窄间隙焊接方法研究

发布时间：2019-01-03 09:31

【摘要】：采用焊剂带约束电弧超窄间隙焊接方法焊接中厚板,具有生产效率高、热输入低的特点,能够降低焊后残余变形和残余应力,具有一定的应用前景。然而,焊剂带的制作效率低且容易破损,严重阻碍了超窄间隙焊接方法在工业方面的推广和应用。为解决上述问题,课题组研制了焊剂片和玻璃纤维网,依靠玻璃纤维网与焊剂片粘接形成焊剂片链替换焊剂带,达到了在坡口内对焊接电弧的稳定约束,并对前期超窄间隙焊枪存在的缺点进一步改进。针对前期超窄间隙焊枪存在枪体支撑刚度不够,结构复杂的问题,设计了两款专用焊枪,第一种焊枪由铜质导电板和钢制支撑板组成以提高焊枪整体刚度,枪头金属罩内填充云母片使其与导电嘴和支撑板绝缘,焊丝通过导电嘴和陶瓷压紧块中间位置时,依靠导电嘴和陶瓷压紧块之间的夹紧力使焊丝与导电嘴紧密接触保证导电性。但在试验过程中,导电嘴会因电弧攀升烧损后不易更换。为此设计了第二种焊枪,该焊枪制作材料选用黄铜,整体结构由上拧螺母、夹丝螺母、枪体三部分构成,上拧螺母保证焊枪与焊机枪柄的固定及焊枪良好导电性,夹丝螺母保证焊丝输送过程与导电嘴始终接触可靠。试验证明,该焊枪解决了第一种焊枪的缺点,能够满足中厚板超窄间隙的焊接。针对焊剂带存在的问题,设计了两种焊剂片结构和编制了玻璃纤维网。第一种焊剂片结构为矩形,第二种结构为带圆形小缺口的矩形,试验中发现,第一种焊剂片与玻璃纤维网粘接的焊剂片链对坡口内焊缝的高低变化适应性差,不利于进行填充、盖面焊接,而第二种缺口型焊剂片制作的焊剂片链能够很好适应。玻璃纤维网是将玻璃纤维绳的四条经线与一条纬线交叉缠绕编制的网状物,并在经纬线交叉处和纬线处涂覆稀释的玻璃纤维浸润剂,促使固化后的玻璃纤维网能够具有一定的刚度,与焊剂片粘接成焊剂片链对折放入坡口内,能够依靠其自身的回弹力使焊剂片与坡口侧壁紧密接触约束电弧。采用焊剂片链约束电弧超窄间隙焊接方法对中厚板Q235A根焊缝的单面焊双面成形影响因素分析得出:焊接电压主要决定坡口侧壁融合,焊接电流决定着根焊缝背部成形,在匹配的工艺参数下,能够实现根焊缝单面焊双面成形。与常规焊接方法相比,利用焊剂片链对电弧产生约束焊接中厚板X70管线钢具有一定的优势。焊接过程热输入小,得到的焊接接头热影响区宽度窄,焊缝区主要为针状铁素体组织,热影响区主要为多边形铁素体组织和贝氏体组织,粗晶区没有产生软化且硬度高于母材,焊缝区和热影响区的冲击韧性均较好。
[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.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG444

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