基于激光焊条件下水龙头壳体制造的新工艺研究

发布时间：2018-04-30 07:47

本文选题：水龙头壳体 + 激光焊接　；参考：《华侨大学》2015年硕士论文

【摘要】：目前水龙头薄壳结构均采用整体铸造的方法来加工制造,高污染、高耗能是该工艺的主要缺点,开发新的制造方法和工艺,尤其是低耗能方法,成了业内的关注点。本文针对水龙头薄壳体,通过分体冲压成型下料,提出采用不锈钢激光焊接的方式来代替纯铜的整体铸造。由于激光焊接过程复杂,为此通过建立水龙头壳体激光焊接热源模型,推导焊接传热方程,建立水龙头壳体有限元模型,对水龙头壳体激光焊进行温度场的数值模拟。结果能够较准确仿真焊接过程,并得知水龙头壳体各方向上热循环曲线,热源前方温度梯度大,变化趋势急剧;热源后方,温度梯度较小,变化较缓。在通孔处其散热模式发生变化,散热效率变低,为实际激光焊接拟定一组基本参数。以基本参数为基础,分析激光焊接各参数对接头表面质量的影响,利用数值优化与实际焊接相结合的方法,得出一组参数:焊接最大功率P=4.0kW,脉宽T=14ms,焊接速度v=5mm/s,离焦量d=-1.0mm。焊得的水龙头焊缝光亮、致密、无气孔等明显缺陷,初步验证了新方法的可行性。为进一步评定水龙头激光焊方法的合理性,对304、310s奥氏体不锈钢激光焊接接头进行性能测试以及微观组织的观察,结果表明水龙头壳体平面变形量均小于规定值0.5mm,其焊缝成型性良好。304、310s两种接头的抗拉强度分别为576、516Mpa,断裂位置均位于焊趾,断裂机制为延性断裂。两种接头抗弯性能良好,弯曲角度达到180°,却未发生断裂。两种接头硬度分布曲线规律一致,焊缝中心较热影响区大,母材硬度值最高。自行设计剪切夹具,对304、310s不锈钢水龙头壳体激光焊接头剪切实验表明,两者抗拉剪平均强度分别为247Mpa,222Mpa,都远高于使用性能标准。水龙头壳体密闭性与耐压检测结果表明水龙头焊缝密闭耐压性能符合焊后要求。接头显微组织观察得知,焊缝中心主要为细小的奥氏体晶粒,往焊缝熔合区,晶粒逐渐粗大,且形状主要为柱状。不同形态晶粒分布,没有明显的界限。通过晶间腐蚀实验发现:310s、304激光焊接接头抗硫酸腐蚀性能好,未发生明显晶间腐蚀。原位观察熔合线的腐蚀过程发现熔合线并未发生明显加宽。其断口微观形貌特征主要为韧窝,间接证明其耐腐蚀性好。对腐蚀后的焊缝金属进行能谱分析,焊缝中心晶粒Cr元素含量接近母材,而腐蚀沟槽中Cr元素较母材下降较多,但其含量仍高于12%,保证了其高的耐腐蚀性。本文研究成果将改变水龙头制造现状,节约经济成本与能耗,为实际生产提供了重大的指导。
[Abstract]:At present, the thin shell structure of the faucet is manufactured by the whole casting method. High pollution and high energy consumption are the main disadvantages of the process. The development of new manufacturing methods and processes, especially the low energy consumption method, has become the focus of the industry. In this paper, the thin shell of the faucet is used for the laser welding of stainless steel through the blanking. Because of the complexity of the laser welding process, the heat transfer equation is derived by establishing the laser welding heat source model of the faucet shell, and the finite element model of the shell shell is established. The numerical simulation of the temperature field is made for the laser welding of the faucet shell. The result can be more accurate to simulate the welding process and know that the welding process is more accurate. The temperature gradient in front of the heat source is large and the change trend is sharp. After the heat source, the temperature gradient is smaller and the change is slow. The heat dissipation mode is changed at the through hole, the heat dissipation efficiency is reduced, and a set of basic parameters are drawn up for the actual laser welding. Based on the basic parameters, the butt of each parameter of the laser welding is analyzed. With the influence of the surface quality of the head, a set of parameters, the maximum power P=4.0kW, the pulse width T=14ms, the welding speed v=5mm/s, the brightness, the density and the no porosity of the faucet weld, are obtained by combining the numerical optimization with the actual welding method. The feasibility of the new method is preliminarily verified. The feasibility of the new method is preliminarily verified. The rationality of the head laser welding method, the performance test and microstructure observation of 304310s austenitic stainless steel laser welding joint, the results show that the plane deformation of the shell is less than the specified value 0.5mm. The tensile strength of the two joint with good welds is 576516Mpa and the fracture position is located at the weld toe, respectively. The fracture mechanism is ductile fracture. The flexural properties of the two joints are good, the bending angle reaches 180 degrees, but there is no fracture. The hardness distribution curves of the two kinds of joints are the same, the weld center is larger than the heat affected zone, and the hardness of the parent material is the highest. The self designed shear clamp is used for the laser welding head shear test of the 304310s stainless steel faucet shell. The average strength of the tensile shear is 247Mpa and 222Mpa, respectively, which is far higher than the standard of performance. The closed and pressure testing results of the faucet shell show that the sealing resistance of the weld is in line with the requirements after welding. The microstructure observation of the joint is that the weld center is mainly fine austenite grain, and the grain is gradually coarse and shape to the weld fusion zone. The main shape is columnar shape. There is no obvious boundary of grain distribution in different forms. Through intergranular corrosion test, it is found that 310S, 304 laser welded joint has good corrosion resistance and no obvious intergranular corrosion. The corrosion process of the in-situ observation fusion line found that the fusion line has not been broadened obviously. The fracture micromorphology is mainly dimple. It is proved that the corrosion resistance is good. The energy spectrum of the weld metal after corrosion is analyzed. The content of Cr element in the central grain of the weld is close to the parent material, while the Cr element in the corrosion groove is much lower than that of the parent material, but its content is still higher than 12%, which ensures its high corrosion resistance. This research will change the current situation of the manufacturing of the faucet and save the economic cost and energy consumption. It provides significant guidance for actual production.

【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG456.7

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