共查询到19条相似文献,搜索用时 234 毫秒
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等离子弧熔覆成形零件的力学性能研究 总被引:3,自引:1,他引:2
介绍一种基于等离子弧熔覆的快速成形工艺.研究不同扫描方向对成形件抗拉强度和延伸率的影响,结果表明,零件的纵向抗拉强度和延伸率均高于横向.通过层间成形方向相互垂直的扫描方式,可以制作整体上各向同性的零件.零件致密度达99.27%,与激光熔覆成形相当. 相似文献
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本文采用尖状磁场约束等离子弧进行加工的方法,试验研究了磁场对等离子弧特性和行为的作用和磁约束等离离子弧对加工质量的影响。实验结果表明,磁约束等离子弧能提高弧的能量密度、刚性和加工能力,改变弧横截面的形状,从而提高了其加工质量。本文研究对等离子弧作为一种半精加工的手段,提供了最有效的途径。 相似文献
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梁桂芳 《机械工人(热加工)》1995,(12):27-28
一、等离子弧割面的质量特性及其评定 1.切割面的质量特性 (1)切口形状 等离子弧切出的切口形状通常如图25所示、其特征是:①上宽下窄,切割面有斜度,且略呈弧线形(氩氢等离子弧切割时呈内凹形)。②左右切割面的倾斜角不相同。 相似文献
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为了扩大等离子弧焊接的应用范围,突破不开坡口只适于工件厚度为8mm以下的限度,本文研究设计了一种微机自适应控制系统,对影响焊接过程稳定性、焊缝表面成形和接头质量的工艺规范参数和工艺措施进行了全面试验,成功地实现了10mm厚ZG4Cr25Ni20钢管的焊接,为等离子弧焊的发展和推广使用开辟了新的前景. 相似文献
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梁桂芳 《机械工人(热加工)》1995,(6):26-27
1.基本特性 空气等离子弧切割是利用干燥的压缩空气作工作气体的一种切割方法。空气中含约80%N_2和约20%O_2,它的切割工艺特性介于氮等离子弧和氧等离子弧切割法之间,主要是为切割工业上应用最多的低碳钢和低合金结构钢而开发的。 由于电弧氛围中存在氧,切割上述结构钢时也发生铁-氧燃烧反应,产生附加热量并形成FeO熔 相似文献
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面能量对激光—电弧复合焊接焊缝及熔滴过渡的影响 总被引:1,自引:0,他引:1
引入面能量的定义,从激光功率、电弧参数和焊接速度等方面来研究面能量的变化对焊缝熔深、熔宽、焊缝成形系数和熔滴过渡的影响,试图建立激光能量与电弧能量之间的最佳配比关系以及面能量与熔深的定量关系。采用高速摄像系统观测熔滴过渡模式和等离子体形态的变化,并采集焊接过程中的电弧和熔滴图像;利用激光共聚焦显微镜观察焊缝形貌,并测量焊缝熔宽、熔深等数据。试验研究发现:激光与电弧两热源之间存在最优匹配范围;电弧电压与焊接电流之间存在U(15 1)0.05I的关系式;焊接速度的降低与焊缝熔深的增加并非线性关系,可选择的焊接速度是一个区间,该区间内存在一个最佳的焊接速度,并对应一个最佳的面能量。因此,在具体的激光—电弧复合焊接中,需要根据板厚、接头形式等确定激光与电弧的能量参数,选择合适的面能量。 相似文献
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STUDY ON THE PRESSURE IN PLASMA ARC 总被引:4,自引:1,他引:4
The axial pressure in plasma arc is measured under different conditions. The effects of the parameters, such as welding current, plasma gas flow rate, electrode setback and arc length, on the pressure in plasma arc are investigated and quantitative analyzed to explain the relationship between the quality of weld and the matching of parameters in plasma arc welding process. 相似文献
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Zezhong C. Chen Maqsood A. Khan 《The International Journal of Advanced Manufacturing Technology》2014,70(5-8):1355-1368
With the development of a new function of computer numerical control controllers, nonuniform rational B-spline (NURBS) interpolation, NURBS tool path generation for sculptured surface machining is under extensive research. The common procedures of the current NURBS tool path planning methods are as follows: first, to find a group of cutter contact points on a sculptured surface; second, to calculate their corresponding cutter locations (CLs); then, to fit a NURBS tool path to the CLs within a prescribed tolerance; and finally, to inspect the tool path for possible gouge by the tool and delete the invalid path segments, if any. However, the NURBS tool path has the following problems: (a) although it passes through the discrete CLs of the theoretical CL path, the deviation along the two paths could be larger than the tolerance; (b) its parameter is not the arc length of the path; and (c) it is difficult to detect gouge along the NURBS path and to remove the invalid segments from it. Consequently, NURBS tool paths generated with the current methods of commercial computer-aided design/computer-aided manufacturing (CAD/CAM) software cannot be used to make smooth and accurate surfaces. To address these problems, this work proposes a new approach to generating arc length parameterized NURBS tool paths with high accuracy in terms of the theoretical CL paths and without gouge and interference. Two practical examples in this work clearly demonstrate the feasibility of this approach and the advantages of the generated NURBS tool paths. Therefore, this approach can be implemented into the CAD/CAM software to promote NURBS machining in industry. 相似文献
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Form-truing error compensation of diamond grinding wheel in CNC envelope grinding of free-form surface 总被引:1,自引:1,他引:0
J. Xie R. M. Zhou J. Xu Y. G. Zhong 《The International Journal of Advanced Manufacturing Technology》2010,48(9-12):905-912
In computer numerical control (CNC) grinding of free-form surface, an ideal arc profile of trued diamond grinding wheel is generally employed to plan 3D tool paths, whereas its form-truing errors greatly influence the ground form accuracy. A form-truing error compensation approach is proposed by using an approached wheel arc profile to replace the previously designed ideal one. The objective is to directly compensate the trued wheel arc-profile errors. It may avoid the time consumption of traditional approach that compensates the measured coordinate point errors of workpiece to an iterative grinding operation. First, the 3D tool path surface was constructed to plan the 3D tool paths. Second, the CNC arc truing of grinding wheel was conducted to analyze the form-truing error distribution relative to the applied wheel arc profile. Then, the form-truing error compensation was carried out in CNC envelope grinding. Finally, the iterative closest point (ICP) algorithm was used to match the measured coordinate points of workpiece to ideal free-form surface. It is shown that the 3D tool path surface constructed is practicable to plan arbitrary 3D tool paths for the form-truing error compensation. The ICP matching may be used to investigate 3D ground form error distribution. It is confirmed that the form-truing error compensation can directly improve the 3D ground form accuracy. It may decrease the 3D ground form error by about 20% when the 2D form-truing error is reduced by about 58% using the same truing conditions for CNC grinding. 相似文献
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An analytical approach for the prediction of forming limit curves subjected to combined strain paths
In the present work, an analytical approach for the prediction of forming limit curves is proposed to incorporate the effect of combined strain paths. The effect of combined strain paths (considering the directional dependency of pre-straining and further straining) is addressed by integrating the incremental equivalent strain expression in two stages i.e., pre-strain and subsequent loading. In each stage, the strain path is assumed to be linear and different combinations of pre-strain (uniaxial, plane-strain and equi-biaxial) are considered. Material anisotropy is taken into account in each stage. The predictions of the present model are compared with the experimental results on forming limit curves under combined strain paths for Al6111-T4 [24] and are found to be in good agreement with each other. 相似文献
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Yongjun Shi Xianfa Lu Peng Yi Zhongyan Liu 《The International Journal of Advanced Manufacturing Technology》2013,66(1-4):515-521
In laser forming, a desired shape for a metal plate can be obtained by controlling a laser scan path and process parameters. The distance planned between parallel scan paths is larger in current laser path planning in order to avoid interference between them, and thus a continuous strain field cannot be formed. In addition, crossed heating lines are also adopted for forming complicated parts. The effects of the parallel and crossed scanning paths on the deformation field were investigated in this paper. The results show that for parallel heating lines, plastic strain fields produced by adjacent scans do not affect each other when the path spacing is greater than the laser spot diameter, but the plastic strain fields produced by the adjacent scans affect each other when the paths spacing is less than the laser spot diameter. A desirable continuous plastic strain field can be achieved by choosing appropriate path spacing and process parameters. For the crossed heating lines, the plastic strain field is different when adopting vertical and diagonal crossings. The influence between the different heating lines must be considered for high-precision laser forming. 相似文献
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复杂航天筒体结构件的焊接应力应变演变规律 总被引:2,自引:0,他引:2
采用有限元分析手段对复杂航天筒体结构件的纵向和环向焊缝温度场和应力场进行模拟。航天筒体焊接采用变极性等离子弧焊工艺,根据变极性等离子弧焊工艺特点使用面高斯热源和圆柱热源的组合热源模型作为变极性等离子弧焊的热源。采用ANSYS软件中ANSYS参数化设计语言(ANSYS parametric design language, APDL)编写程序,实现变极性等离子弧焊接热源在筒体结构上加载和移动,完成四道纵缝和两道环缝的焊接热力过程仿真。通过对模拟结果分析,解释复杂筒体焊接应力应变的演变过程。发现在焊接过程中纵缝两端有明显的应力-应变释放,交叉部位的变形直接影响到结构整体的尺寸精度。 相似文献
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从4个方面就变形路径对成形极限图影响的研究现状进行综述,并进一步论述了复杂变形路径和单一变形路径的概念,以及基于Hill'48屈服准则的塑性应变几何关系.为了在任意复杂变形路径下计算冲压板材的失稳极限应变,提出"任意复杂变形路径均可简化为线性复合变形路径"、"板材的冲压成形能力亦即板材允许的极限厚度应变",以及"板材在线性复合变形路径下的冲压成形能力取决于其最终变形路径的应变比值"等3个工程简化假设,并对它们进行立论和诠释.同时基于这些假设,在板材承受线性复合变形路径和前后变形路径的应变主轴发生转动的条件下,解析和推导出计算冲压成形极限应变的理论公式.利用这些简化假设和理论公式,可以在任意复杂变形路径下计算板材的冲压成形极限应变并绘制其冲压成形极限图. 相似文献