空心异形铝型材挤压模具设计及工艺优化

发布时间：2018-09-05 20:31

【摘要】：铝型材因其质量轻、机械性能优良、整体成型度高等特点,其应用领域已从传统的建筑行业拓展到以航空航天、交通运输为代表的工业领域中,并朝大型化、截面复杂化的方向发展。这不仅对铝型材的性能提出了更高的要求,也使型材挤压成形工艺面临着更严峻的挑战。扭拧、波浪、裂纹、表面粗糙等是铝型材常见的缺陷,这些缺陷多与铝锭的质量、模具的结构、工艺参数有关。本课题从铝型材挤压过程入手,首先探究了铝锭均匀化处理对挤压过程的影响,接着以一种空心异型材为例,进行了分流组合模的设计,借助于挤压模拟软件HyperXtrude对模具结构和挤压工艺进行了改进和优化。本文主要研究的内容如下:(1)对未均匀化和均匀化处理过的6063铝合金铸锭进行了金相组织观察和硬度测试。结果显示:在570℃的加热条件下,保温时间越长,合金成分越均匀,硬度随保温时间的延长逐渐降低;但当保温时间由8h变为12h,金相组织和硬度差别并不大。实际生产试验情况表明,经均匀化处理过的铝锭变形抗力较低,可以用更小的挤压力进行挤压生产,对未均匀化铝锭进行挤压前长时间加热(480℃)也可以达到部分均匀化的效果,但其效果并不明显。(2)针对选取的型材产品的结构,从分流孔、分流桥、焊合室、桥墩、工作带等方面进行了挤压模具设计。使用挤压模拟软件HyperXtrude进行了挤压过程模拟分析,发现模桥与模芯结合处出现了应力集中,型材出料口流速差异较大,针对此问题对分流桥、分流孔和工作带进行了改进,最终使最大模具应力由1183MPa降至872MPa,并将型材出料口各部位速度差降低到10mm/s内,相比改进之前有了较大的改善。(3)三温一速是挤压过程中最重要的工艺参数。采用正交实验的方法研究了挤压速度、铝锭温度、模具温度、挤压筒温度对挤压力和型材出料时速度均匀程度的影响。以挤压力和速度均方差作为考察指标,对正交实验结果进行极差分析,得到最佳工艺参数组合(挤压速度2mm/s、模具温度470℃、坯料温度500℃、挤压筒温度460℃)。(4)实际生产试验表明,采用改进过的分流模和挤压工艺参数可以挤制出表面质量良好,没有波浪、扭拧等缺陷的型材产品。本文将有限元模拟技术和数学优化方法应用于型材挤压过程的分析和工艺参数优化中,能够给模具的设计和挤压工艺的制定提供一定的指导,这对企业提高产品质量和生产效率,增强市场竞争力有重要意义。
[Abstract]:Because of its light weight, excellent mechanical properties and high overall formability, aluminum profiles have been extended from the traditional construction industry to the aerospace, transportation and other industrial fields, and are developing towards large-scale, cross-sectional complex direction. This not only puts forward higher requirements for the performance of aluminum profiles, but also makes the profile extrusion. Forming process is facing more severe challenges. Torsion, wave, crack, surface roughness and other common defects of aluminum profiles, these defects are mostly related to the quality of aluminum ingot, die structure, process parameters. The main contents of this paper are as follows: (1) The microstructure and hardness of 6063 Aluminium alloy ingot which has not been homogenized and homogenized were observed and tested. The longer the holding time is, the more homogeneous the alloy composition is, and the hardness decreases gradually with the extension of holding time. However, when the holding time is changed from 8 h to 12 h, the difference of microstructure and hardness is not great. The actual production test shows that the deformation resistance of the homogenized aluminum ingot is lower, and it can be extruded with smaller extrusion force. The effect of partial homogenization can also be achieved by heating the non-homogenized aluminum ingot for a long time before extrusion (480 C), but the effect is not obvious. (2) According to the structure of the selected profiles, the extrusion die was designed from the diversion hole, diversion bridge, welding chamber, pier, working belt and so on. The extrusion simulation software HyperXtrude was used to carry out the extrusion die design. The simulation analysis of extrusion process shows that the stress concentration appears at the joint of die bridge and die core, and the flow velocity at the outlet of profile material varies greatly. In view of this problem, the diversion bridge, diversion hole and working belt are improved. Finally, the maximum die stress is reduced from 1183 MPa to 872 MPa, and the velocity difference at each part of the profile outlet is reduced to 10 mm/s. (3) Three temperatures and one velocity are the most important parameters in the extrusion process. The effects of extrusion speed, aluminum ingot temperature, die temperature and extrusion cylinder temperature on the extrusion force and velocity uniformity are studied by orthogonal experiment. The optimum combination of process parameters (extrusion speed 2mm/s, mold temperature 470, billet temperature 500, extrusion tube temperature 460) was obtained by range analysis. (4) The actual production test showed that the profile products with good surface quality, no wave, twist and other defects could be extruded by using the improved splitting die and extrusion process parameters. Finite element simulation technology and mathematical optimization method are applied to the analysis of profile extrusion process and the optimization of process parameters, which can provide certain guidance for the design of die and the formulation of extrusion process. It is of great significance for enterprises to improve product quality and production efficiency and enhance market competitiveness.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG379

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