不锈钢电弧增材制造成形工艺研究及尺寸精度控制

发布时间：2018-03-24 04:34

本文选题：等离子弧　切入点：增材制造　出处：《南京理工大学》2017年硕士论文

【摘要】：电弧增材制造技术是金属3D打印的一个重要研究方向,目的是快速生产复杂结构件,其全焊缝组织具有结构致密、力学性能高的特点。本文以等离子弧为热源,ER308不锈钢焊丝为填充材料,开展了对电弧增材工艺及尺寸精度控制的研究,在此基础上完成典型试件的电弧增材制造。首先研究了单层单道及多层单道成形工艺。研究了不同参数下成形形貌及成形精度,制定了工艺参数匹配范围。对起弧熄弧端尺寸偏差较大进行分析并提出尺寸控制策略:对直壁体,利用起弧端成形尺寸大与熄弧端成形尺寸小的特点,采用往复式堆积方式进行互补,同时降低起弧端的电流和送丝速度、增大堆覆速度,增大熄弧端的送丝速度、减小堆覆速度,达到端口尺寸的有效控制;对封闭环形,形成起弧端与熄弧端的搭接,搭接长度为8mm可有效控制搭接处的高度。然后开展了对尺寸精度控制的研究,建立熔敷层尺寸(宽度、高度)与工艺参数(堆覆电流、堆覆速度及送丝速度)之间的模型。采用正交旋转组合试验的方法,利用MATLAB软件拟合得到尺寸与参数的二次回归模型。采用因子置零方法分析单因子及多因子参数对堆覆层尺寸的影响,结果表明参数对层宽尺寸影响大小为:堆覆速度送丝速度堆覆电流;对层高尺寸影响大小为:送丝速度堆覆速度堆覆电流。由拟合得到的两个方程,通过调节参数可有效控制尺寸,并达到优化参数的目的。接着对堆覆层的显微组织和力学性能进行研究。研究发现不锈钢堆覆构件组织由奥氏体和少量铁素体组成,其抗拉强度较好,达到510MPa以上,且竖直方向高于水平方向。应力分布具有明显的规律:高度方向上,两端硬度高,中间部分硬度低;宽度方向上,两边硬度低,焊缝中心处硬度高。最后,基于等离子电弧增材制造系统,确定了复杂环形壳体的堆覆成形策略,用等离子电弧增材制造技术制造出瓶状壳体件,并检验其外观,结果表明:除去起弧熄弧点处,壁厚最大相对误差为5.37%,最大误差值为0.22mm,熔敷效率达到0.197kg/h。
[Abstract]:Arc material augmentation manufacturing technology is an important research direction of metal 3D printing. The purpose of this technology is to produce complex structural parts quickly, and the structure of the whole weld is compact. The characteristics of high mechanical properties. In this paper, plasma arc is used as the heat source of stainless steel wire E308 as filling material, and the process of arc material increasing and the control of dimension precision are studied. On the basis of this, the fabrication of the typical specimen is completed. Firstly, the single-pass and multi-layer single-pass forming processes are studied, and the shape and precision of the forming process under different parameters are studied. The matching range of process parameters is established. The large deviation of the dimension of the arc extinguishing end is analyzed and the dimension control strategy is put forward: for the straight wall body, the characteristics of the large size of the starting end and the small size of the end of the arc extinguishing are used. The reciprocating stacking method is used to complement each other, and at the same time, the current and wire feeding speed at the starting arc end are reduced, the stacking speed is increased, the wire feeding speed at the extinguishing end is increased, and the stack speed is reduced to achieve the effective control of the port size. The lap length of 8mm can effectively control the height of the lap. Then, the dimension (width, height) and process parameters (stack current) of the cladding layer are established. Models between stacking speed and wire feeding speed. The quadratic regression model of size and parameter was obtained by MATLAB software. The influence of single factor and multi-factor parameters on the size of the cladding was analyzed by factor zeroing method. The results show that the influence of the parameters on the width of the layer is as follows: the wire feeding speed of the stack current and the stacking current of the height of the layer are: the stacking current of the wire feeding velocity. By adjusting the parameters, the size can be effectively controlled and the parameters can be optimized. Then, the microstructure and mechanical properties of the cladding are studied. It is found that the microstructure of the stainless steel cladding member is composed of austenite and a small amount of ferrite. The tensile strength is higher than 510MPa, and the vertical direction is higher than the horizontal direction. The stress distribution has obvious regularity: in the height direction, the hardness of both ends is high, the hardness of the middle part is low, the hardness of both sides is low in the width direction, The hardness is high at the center of the weld. Finally, based on the plasma arc material increasing manufacturing system, the stacking and reforming strategy of the complex annular shell is determined, and the bottle shell is manufactured by the plasma arc material increasing technology, and the appearance of the shell is tested. The results show that the maximum relative error of wall thickness is 5.37 mm, the maximum error is 0.22 mm, and the deposition efficiency is 0.197 kg / h.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG142.71;TG661

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