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Designing the optimal shape for an extrusion die to produce a high-quality extrusion product is often required by industry.
Design from experience is unsatisfactory for achieving the flexibility and precision requirements in die design. In this paper,
a design method has been developed for the optimum shape design of extrusion die. The extrusion process was modelled and analysed
by using the finite-element method to obtain the extrusion force and effective strain for different die shapes. A polynomial
network was applied to identify the force and strain models in terms of the geometric parameters of the extrusion die. An
improved genetic algorithm was used to optimise the identified model for optimal shape with minimum force and strain. It has
been verified that the modelling error is extremely small. The designer can quickly and accurately access the optimal shape
of an extrusion die through this new approach.
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ID=" <E5>Correspondence and offprint requests to</E5>: Dr Y.-C. Hsu, Department of Mechanical Manufacturing Engineering,
National Huwei Institute of Technology, 64 Wun-Hua Road, Huwei, Yunlin, Taiwan. E-mail: jasonych@sunws.nhit.edt.tw 相似文献
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An approximate model has been developed to improve our understanding of flow control at the exit of an extrusion die. This paper deals with the design of traditional die flow correctors used in flat-faced aluminum extrusion dies. The numerical model uses the finite-element method combined with techniques of mathematical programming. Analytical sensitivities have been developed from the discretized finite-element equations in order to compute the necessary derivatives during optimization. The model includes thermal effects, and the extruded material is assumed to be strain-rate and temperature dependent. 相似文献
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In this study, fatigue behavior of cold extrusion dies is investigated analytically. Experimental studies and practical experience have shown that fatigue cracks occur at the inlet radius of die shoulders. The highest stress concentration is found also at the same location. For this reason, effective stress intensity factors at different locations of the die-shoulder inlet of a typical axisymmetric extrusion die have been calculated by using the finite element method. The crack growth has been simulated by applying the Paris/Erdoĝan fatigue law to the computed data. Finally, service life of the extrusion die has been estimated from the crack-growth-rate. Agreement of theoretical estimations with available data is found to be satisfactory within the limits of experimental uncertainties. Furthermore the experimental behavior of the crack growth (stable-unstable-stable growth with final fracture) is simulated correctly. It has been shown that the unexplained behavior is caused by decrease of stress concentration with increasing crack-length. 相似文献
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Alunda Bernard Ouma Jeonghwan Nam Lim Hyun Seok Jai Sug Hawong 《Journal of Mechanical Science and Technology》2012,26(8):2617-2626
The square ring has over the past few years been used as an alternative sealing element to the O-ring, which has been used widely for a long time. The square ring geometry is believed to be especially suitable for axial static applications because its square form remains practically constant under high pressures, has a high resistance to extrusion, not sensitive to gap extrusion and high leak tightness. Some of these fundamental properties that are crucial in the design of a square ring can be justified by analysis of the stress distribution of the square ring under various loading conditions, especially under a combined loading of uniform squeeze and internal pressure. In order to justify these properties a stress frozen square ring under this combined loading condition of uniform squeeze rate and internal pressure was analyzed using the photoelastic experimental hybrid method to obtain the contact and internal stresses. This research confirmed that contrary to the established theory, the square ring extrudes at a lower pressure of 1.96 MPa. The photoelastic experimental hybrid method can adequately be used for stress analysis of square ring seals. Internal pressure plays a significant role in the design of the seals. As the internal pressure increases, the internal stresses also increase. Maximum internal stresses were observed in the region close to the extrusion gap at points 2 and 2??. The square ring experienced contact stress singularity on the upper end of the contact surface (point 2??) on the front side and at point 2 on the upper side. The upper region experienced the largest contact stresses as well as internal stresses and so the fracture criterion of maximum shear stress should be applied in this region. 相似文献
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Guoqun Zhao Hao Chen Cunsheng Zhang Yanjin Guan 《The International Journal of Advanced Manufacturing Technology》2013,69(5-8):1547-1556
The extrusion die plays a crucial role in aluminum alloy profile production, which influences product quality and service life of extrusion die directly. In this paper, a profile with irregular shape was taken as an analysis example, and multiobjective optimization for porthole extrusion die based on modern intelligence algorithm was carried out. Aiming at achieving the uniform velocity distribution in the cross-section of the profile as well as decreasing the maximum stress on the extrusion die and the deflection of the mandrel, the angle between port bridges, the position of die orifice, and the height of welding chamber were considered as the design variables. Then Kriging model was established on the basis of Latin hypercube samplings, and above design variables were optimized using Pareto-based genetic algorithm. Finally, an optimal die structure is gained. Compared with the initial scheme, the velocity distribution in the extrudate was more even, and the stress on the die and the deflection of the mandrel were decreased obviously in the optimal scheme. The optimal design method for porthole die has strong commonality, thus, it could give useful guidelines for practical production of the same kind of aluminum profile. 相似文献
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锥齿轮冷挤压成形加工数值模拟研究 总被引:1,自引:0,他引:1
为了解决人工设计锥齿轮冷挤压模具过度依赖经验的问题,将数值模拟应用到锥齿轮模具设计中。设计了一套用于冷挤压加工锥齿轮的三层组合凹模,制定了相应的工艺措施,利用Deform-3D软件对锥齿轮的冷挤压加工过程进行了数值模拟,分析了加工过程中的载荷曲线、速度场、应力场和温度场,获得了有关锥齿轮变形规律的基本情况。研究结果表明,通过改善润滑条件、优化模具几何参数可以提高冷挤压加工锥齿轮的成形质量,并对锥齿轮冷挤压加工工艺流程定制、模具设计具有一定的指导意义。 相似文献
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E. V. Artamonov T. E. Pomigalova N. I. Smolin M. O. Chernyshov 《Russian Engineering Research》2018,38(8):632-634
The stress–strain state of replaceable polyhedral inserts in composite tools is calculated by the finite-element method. The influence of the insert’s design parameter, the basing and attachment configuration, and the load on the stress and strain is established. Besides the strength of the inserts, attention is paid to the positional accuracy in the tool housing. Cutting inserts of maximum strength have been developed and patented. 相似文献
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高汉华 《中国制造业信息化》2006,35(7):62-65
对冷挤压模受内压作用应力分布规律的研究,能避免凹模在使用时发生早期的断裂失效,为组合凹模的设计和应用提供一定的依据。采用有限元分析软件对转子冷挤压模进行建模,在此基础上,模拟了在整体内压和局部内压下凹模的受力情况,并对模拟结果进行分析比较,得出了不同内压作用时凹模应力的分布规律。 相似文献
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高汉华 《中国制造业信息化》2006,35(4):62-65
对冷挤压模受内压作用应力分布规律的研究,能避免凹模在使用时发生早期的断裂失效,为组合凹模的设计和应用提供一定的依据。采用有限元分析软件对转子冷挤压模进行建模,在此基础上,模拟了在整体内压和局部内压下凹模的受力情况,并对模拟结果进行分析比较,得出了不同内压作用时凹模应力的分布规律。 相似文献
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Despite increasing demand for and application of three-dimensional extrusion of various sections through continuous dies, so far very little work has been done by systematic and general analysis to predict the plastic flow properly. For effective die design, efficient design method and the related method of theoretical analysis are required for extrusion of complicated sections. In generalized three-dimensional extrusion of sections through continuous dies, a new method of die surface representation, using blending function and Fourier series expansion, is proposed by which smooth transitions of die contour from the die entrance to the die exit are obtained. The flow patterns as well as the upper-bound extrusion pressures are obtained on the basis of the derived velocity field. The effects of area reduction, product shape complexity, die length and frictional condition are discussed in relation to extrusion pressure, the distorted grid pattern and distribution of the final effective strain on the cross-section of the extruded billet. As computational examples for arbitrarily-shaped products rounded rectangles and ellipses are chosen for the extruded sections. Experiments are carried out for aluminum alloys at room temperature for a rounded square section and an elliptic section. In order to visualize the plastic flow, the grid-marking technique is employed. The theoretical predictions both in extrusion load and deformed pattern are in good agreement with the experimental results. 相似文献
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由于变形剧烈,复杂铝型材挤压成形有限元模拟会因网格不断重划分而精度欠佳。文中基于可以有效避免网格重划分难题的有限体积法,对铝合金门轴固定产品的热挤压过程进行数值模拟,详细分析挤压成形中各个阶段金属流动情况以及应力、应变、温度、速度等场量的分布变化情况。棒料进人模口至完全流出工作带这段时间是型材挤压最为困难的阶段,材料在工作带处的应力、应变最大,温度最高,因而对模具工作带处造成的磨损也最为严重。进人到最终稳定挤压阶段时挤压方向金属流速计算值与理论挤出速度吻合很好。模拟结果表明所用有限体积法是有效的,可以为铝型材挤压的模具设计与工艺参数的选择提供理论指导。 相似文献
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L. X. Li K. P. Rao Y. Lou D. S. Peng 《International Journal of Mechanical Sciences》2002,44(12):2415-2425
Hot extrusion of Ti–6Al–4V alloy has been studied using finite element simulation and the results are compared with those obtained experimentally. First, the constitutive behavior of the material and friction at the extrusion temperatures are established based on the results obtained through cylindrical and ring compression tests, respectively. While the flow stress below β transus temperature is expressed as a strain-dependent function, it is taken as strain-independent one at higher temperatures. The distribution of strain, temperature and effective stress has been simulated under different design and processing conditions. Simulation results show that heat generation due to deformation is significant (as much as 160°C) in the hot extrusion of Ti alloys, and it mainly occurs at the beginning of the extrusion process. This leads to reduction in flow stress which, in turn, leads to enlarged deformation zone. A fair agreement has been found between the experimental results and those obtained through simulations. 相似文献
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以6304轴承套圈冷辗扩为例,介绍深沟球轴承套圈的冷辗扩工艺编制及其冷辗模具的设计方法。其中给出的部分经验数据使冷辗模具设计简单实用。 相似文献
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通过对摩托车倒档锥度环温挤压成形过程进行有限元模拟与分析,解决成形过程中出现的问题,并设计出摩托车倒档锥度环的温挤压成形模具。模拟结果显示,优化工艺参数后的成形件质量良好,只有少量纵向毛刺和飞边,材料利用率高,表明温挤压是一项有效的毛坯精化技术。 相似文献
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K. Abrinia M. Makaremi 《The International Journal of Advanced Manufacturing Technology》2009,41(7-8):670-676
Spread extrusion could be used for manufacturing of wide profiles in the extrusion industry. In this paper a new method of design and analysis has been presented for such a problem. Special dies were designed for profiled sections such as square, rectangular, elliptical and cross shapes. These dies force the material to flow sideways and spread so as to extrude sections with wider dimensions than the initial billet or the maximum container diameter. The geometry of the deforming zone in the die was formulated and based upon that, a kinematically admissible velocity field was derived. Using this velocity, we estimated the field upper bound on extrusion power. Profile sections with different aspect ratios were investigated and the influence of other process parameters such as friction and reduction of area on the extrusion pressure were studied. Optimum die lengths for each die were calculated so as to minimize the extrusion pressure. Finite element analysis for the numerical simulation of the process was also carried out. The finite element results were also used as an aid to the design process of the extrusion dies. Dies were manufactured for different sections such as square, rectangle, and ellipse and cross shapes. Experiments were carried out to obtain data to verify the theory. Comparison of the results showed good agreement between the theoretical, numerical and experimental data. It was concluded the present method could be used to design dies for the spread extrusion of different shaped dies. 相似文献
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Akshaya Kumar Rout Kalipada Maity 《The International Journal of Advanced Manufacturing Technology》2011,54(5-8):495-506
The geometry of die profile plays a major role in reducing the extrusion pressure and ensuring the smooth flow of material. In general, the extrusion process is mostly affected by billet geometry, die geometry, and interface frictional force at the die billet geometry. In the present investigation, an analysis using three-dimensional upper bound method using fifth-order die profile function has been carried out for extrusion of square sections from square billet. The extrusion pressure and optimum die length have been computed by multivariable optimization technique. The present die shape profile is found to be superior to many other profiles. The results obtained will help in design of optimum die profile and investigation of its performance. 相似文献