曲母线件无芯模旋压辅助支撑方式的研究

发布时间：2018-11-22 13:02

【摘要】：旋压成形是实现薄壁回转体类零件的少无切削加工先进制造技术,以其产品精度高、工艺柔性好、节约材料、易于实现机械化与自动化等诸多优点而成为塑性成形技术的重要发展方向。但普通旋压工艺生产特定工件需要配备特定芯模,应用于多品种、小批量的生产时受到限制。近年来的无芯模旋压成形虽然脱离了特定芯模的限制,但由于板料单面受力,造成加工不稳定,加工件易产生明显的回弹变形,形状精度存在明显误差。针对上述技术难题,本文提出了采用辅助支撑的方式对曲母线件进行无芯模旋压成形,增大了板料的塑性变形,提高了成形件的形状精度。本文的主要内容和贡献如下:(1)基于ANSYS/LS-DYNA有限元软件显示动态方法构建了无芯模旋压成形工艺综合仿真模型:通过提取加工中的关键部件尺寸,建立了符合实际曲母线件无芯模旋压的综合仿真模型,并通过能量法和实验对比法对模型进行了有效性验证,为后续基于辅助支撑的无芯模曲母线件旋压研究奠定了基础。(2)提出了基于辅助芯模支撑的无芯模旋压方法:通过采用与曲母线轮廓初始段相契合的辅助芯模进行支撑,与无支撑的无芯模旋压进行对比,采用仿真与实验对比的方式,研究了基于辅助芯模支撑的无芯模旋压方法对板料成形形状精度及壁厚减薄的影响。实验证明辅助芯模支撑无芯模旋压的最大形状误差为8.11mm,比无支撑的无芯模旋压提高了 81.94%,平均形状误差为1.60mm,比无支撑的无芯模旋压提高了 92.45%。并通过对三条加工轮廓曲线的仿真和实验加工,对比加工件的形状和壁厚精度,实验证明三条轮廊曲线辅助芯模支撑无芯模旋压加工的最大形状误差的算术平均值为6.45mm,平均形状误差的算术平均值为1.61mm。说明辅助芯模支撑的无芯模旋压方法对板料成形整体弯折影响较大,但对凹凸程度较大的曲母线,加工中会出现过变形。(3)提出了基于辅助旋轮脉动支撑和随动支撑的无芯模旋压方法:将板料在径向方向上的变形过程看成板料的局部变形,沿径向方向划分为若干个小段,并对每个小段用辅助旋轮进行支撑。采用仿真和实验对比的方式,分别对三条曲母线轮廓进行加工,对比加工件的形状和壁厚精度,研究了基于脉动支撑和随动支撑的无芯模旋压方法对板料成形形状精度及壁厚减薄的影响。实验证明辅助旋轮脉动支撑无芯模旋压加工的最大形状误差的算术平均值为19.66mm,平均形状误差的算术平均值为10.19mm,随动支撑无芯模旋压加工的最大形状误差的算术平均值为19.68mm,平均形状误差的算术平均值为9.80mm,但加工件形状与目标形状相仿,无过变形产生。(4)提出了基于复合脉动支撑和复合随动支撑的无芯模旋压方法:综合了辅助芯模支撑和辅助旋轮支撑在板料成形中的优势,提出了同时采用辅助芯模和辅助旋轮进行复合支撑的无芯模旋压方法。采用仿真和实验对比的方式,分别对三条曲母线轮廓进行加工,对比加工件的形状和壁厚精度,研究了基于复合脉动支撑和复合随动支撑的无芯模旋压方法对板料成形形状精度及壁厚减薄的影响。实验证明复合脉动支撑无芯模旋压加工的最大形状误差的算术平均值为8.87mm,平均形状误差的算术平均值为3.70mm;复合随动支撑无芯模旋压加工的最大形状误差的算术平均值为4.55mm,平均形状误差的算术平均值为1.37mm,无过变形产生,成形效果为最优。(5)对基于五种辅助支撑方式的无芯模旋压方法进行了综合对比,并对最优成形方式进行了应用实例验证。从加工件整体及部分的轮廓形状精度及壁厚减薄情况深入分析了各种支撑方式对产品加工的综合影响,并将辅助支撑对无芯模旋压加工的影响程度进行了量化表示。最后,对最优方式的复合随动支撑无芯模旋压方法采用五种不同的加工轮廓曲线进行了实验加工,实例加工件的最大形状误差在5.91mm左右,平均形状误差在2.48mm左右,最小壁厚在1.19mm左右,最大壁厚减薄率在36.68%左右,平均壁厚减薄率在20.14%左右。进一步验证了复合随动支撑在无芯模旋压加工不同曲母线件上的加工柔性。
[Abstract]:Spinning and forming is an advanced manufacturing technology for machining thin-wall rotary body parts, and has the advantages of high product precision, good process flexibility, material saving, easy realization of mechanization and automation, and the like, and becomes an important development direction of the plastic forming technology. but the common spinning process is required to be provided with a specific core die for the production of a specific workpiece, and is applied to the production of a plurality of varieties and small batches. In recent years, the non-core die spinning formation has been limited by the specific core die, but the processing is not stable due to the single-side stress of the sheet, and the workpiece is easy to produce obvious springback deformation, and the shape precision has obvious error. In view of the above technical problems, this paper puts forward the non-core die spinning forming of the curved bus bar by means of auxiliary support, and the plastic deformation of the sheet is increased, and the shape precision of the forming part is improved. The main content and contribution of this paper are as follows: (1) Based on the ANSYS/ LS-DYNA finite element software display dynamic method, a comprehensive simulation model of the non-core die spinning forming process is built: by extracting the key components in the process, a comprehensive simulation model of the non-core die spinning of the actual curved generatrix is established, The validity of the model is verified by the energy method and the experimental comparison method. (2) a non-core die spinning method based on an auxiliary core die support is provided, The influence of the core die-free spinning method on the shape precision and the thickness of the wall is studied. The experimental results show that the maximum shape error of the core-die-supported die-free spinning is 8.11mm, the spinning of the non-supported core-free die is improved by 81.94%, the average shape error is 1.60mm, and the spinning of the non-supported die-free die is improved by 92.45%. The results show that the arithmetic mean value of the maximum shape error of the three-wheel gallery curve auxiliary core die to support the non-core die spinning process is 6.45mm, and the arithmetic mean value of the average shape error is 1.61mm. The non-core die spinning method of the auxiliary core die support has great influence on the whole bending of the sheet metal forming, but the bending bus with a large degree of concave and convex is deformed in the processing. (3) The non-core die spinning method based on the auxiliary rotary wheel pulse support and follow-up support is proposed: the deformation process of the plate in the radial direction is regarded as the local deformation of the sheet material, the radial direction is divided into a plurality of small sections, and the auxiliary rotating wheel for each small section is supported. By means of simulation and experimental comparison, three curved bus lines are processed, the shape and the wall thickness precision of the work piece are compared, and the influence of the non-core die spinning method based on the pulse support and the follow-up support on the shape precision and the thickness of the wall is studied. The experimental results show that the arithmetic mean value of the maximum shape error of the non-core die spinning process of the auxiliary rotating wheel is 190.66mm, the arithmetic mean value of the average shape error is 10.19mm, and the arithmetic mean value of the maximum shape error of the follow-up support non-core die spinning process is 19.68mm, The arithmetic mean of the mean shape error is 9.80mm, but the shape of the work piece is similar to the shape of the target, and no deformation occurs. (4) The non-core die spinning method based on composite pulse support and composite follow-up support is proposed: the advantages of the auxiliary core die support and the auxiliary rotating wheel support in the sheet metal forming are integrated, and the core die spinning method with the auxiliary core die and the auxiliary rotating wheel for composite support is put forward. By means of simulation and experimental comparison, three curved bus lines are processed, the shape and the wall thickness precision of the work piece are compared, and the influence of the core-free die spinning method based on the composite pulse support and the composite follow-up support on the shape precision and the thickness of the wall is studied. and the arithmetic mean value of the maximum shape error of the composite follow-up support non-core die spinning process is 4.55mm, The arithmetic mean value of the average shape error is 1. 37mm, no deformation is generated, and the forming effect is optimal. (5) The method of non-core die spinning based on five auxiliary support modes is compared, and the application example verification is applied to the optimal forming mode. In this paper, the comprehensive influence of various kinds of support methods on the product processing is deeply analyzed from the precision of the profile and the thickness of the wall in the whole and part of the work piece, and the degree of influence of the auxiliary support on the non-core die spinning process is quantified. In the end, five different machining profile curves were used for the composite follow-up support of the best mode. The maximum shape error of the case was about 5.91mm, the average shape error was about 2.48mm, and the minimum wall thickness was about 1. 19mm. The thinning rate of the maximum wall thickness is about 36.68%, and the thinning rate of the average wall thickness is about 20. 14%. and the processing flexibility of the composite follow-up support on the different curved bus bars is further verified.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG306

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