AZ31镁合金管材挤压成型数值模拟与实验研究

运用基于AZ31镁合金本构方程与ALE算法的HyperXtrude软件对典型AZ31薄壁管材的挤压过程进行数值模拟,并通过调整焊合室高度、焊合室大圆角及焊合室坡度3个结构参数,分析不同条件下应力分布与速率分布的变化情况。结果表明:焊合室内近工作带处压力随焊合室高度增加不断减小,分流孔与焊合室压力的最大值与平均值均随焊合室大圆角增大发生降低,分流孔与焊合室压力随焊合室入口坡度增大不断增大,并在焊合室高度为16mm、大圆角为18mm以及入口坡度为15°时金属流速均方差达到最小值。优化模具结构缓解了应力集中与流速不均等问题,在实验生产中得到合格产品,型材组织均匀细化。     

分流模挤压非对称断面铝型材有限元数值模拟分析

采用了一种基于Deform-3D结合Pro/Engineer的对分流模挤压过程中焊合面相互穿透网格进行重构的技术,并对空心型材分流模挤压过程中金属的流动行为、温度场及模芯受力情况进行了模拟分析。结果表明,网格重构技术对于空心型材挤压的数值模拟具有可行性,可实现焊合面与对称面不一致(非流动对称面)空心型材的分流、焊合及成形的挤压全过程的仿真,从而为研究挤压全过程(尤其是焊合过程)的金属流动行为、模具结构的合理性、变形体的温度场分布情况、焊合阶段模具的受力等提供了一种新的计算分析方法。     

异形管材分流模挤压焊合过程金属流变及模具受力的模拟分析

针对采用有限元模拟时焊合面不能设置为刚性对称面的空心型材,其焊合过程不能模拟计算的问题,提出了基于有限元法结合逆向工程技术的焊合面网格重构技术的解决方法,并采用该方法对异形管材分流模挤压的焊合过程进行了模拟分析.研究结果表明:当挤压行程为33.1 mm时完成了焊合,焊合温度范围477~496℃,焊合室内静水压力为169~3 463 MPa,满足焊合要求;分流桥的焊合角部位所受应力最大,约为205 MPa.模具结构设计合理.     

大型复杂薄壁铝合金空心型材挤压成形工艺

目的 解决大型复杂薄壁铝合金空心型材挤压过程中材料流速均匀性控制难,以及模具局部应力集中导致模具寿命低、挤压型材尺寸稳定性差的问题。方法 采用有限元模拟方法对此类典型型材挤压过程进行仿真分析,根据仿真结果中型材出口材料流速分布情况,通过调控不同部位材料流入量及材料流动阻力,并以型材出口流速差和流速均方差（SDV）作为衡量挤压过程中材料流速均匀性的指标,逐步迭代优化模具结构以提高材料流动均匀性;根据仿真结果中挤压模具应力分布情况,以模具最高应力作为衡量模具强度的指标,逐步迭代优化模具结构以减小模具应力。结果 通过迭代仿真依次优化模具工作带长度、分流孔尺寸、阻流块高度等参数,最终型材出口流速差由25.07 mm/s降至2.72 mm/s,流速均方差由9.84 mm/s降至0.72 mm/s;通过迭代仿真优化焊合角度,最终模具最高应力由945 MPa降至863 MPa。采用基于有限元仿真优化结构的挤压模具成功制备了合格的铝合金型材样件,挤压试验结果与数值模拟结果吻合。结论 通过优化模具工作带长度、分流孔尺寸及阻流块高度,调控不同部位材料流入量及材料流动阻力,能够有效解决大型复杂薄壁铝合金空心...     

复杂断面空心铝型材分流模挤压焊合过程金属流变行为分析

采用有限元法结合焊合区网格重构技术,揭示了复杂断面空心铝型材焊合时的金属流变行为,优化了分流孔面积、位置、宽展角等结构参数,使得同步焊合面由原来1个增加到5个,消除了型材断面中部流速快、左部慢与底面卷翘等成形缺陷。焊合室内最大静水压力达484MPa,能够满足焊合质量,模芯周围受力分布均匀,有利于减小型材壁厚超差。     

分流焊合模成形管材过程的数值模拟研究

采用FEM方法对分流焊合模成形管材的挤压变形过程进行了三维模拟,给出了管材挤压过程中铝合金的应力、应变及流动速度等的分布和变化.     

铝合金空心型材挤压焊合问题的研究进展

从挤压焊缝的形成、固态焊合机理、焊合质量与工模具设计的关系、焊合质量判据等方面综述了国内外铝合金空心型材挤压焊合问题的研究现状.     

导流角对挤压变形流动的影响机理分析

针对平模挤压时常因金属流速不均匀而易产生缺陷,本文采用了带导流角结构的芯模进行挤压研究.通过数值模拟和实验,深入分析了挤压过程中金属变形流动行为的机理,结果表明:带导流角芯模挤压时筒底不出现分流的现象,"死区"显著地缩小;处于塑性区内材料的应变类型由三种变为均一的拉伸类,显著地提高了金属变形流动的均匀性,利于金属的挤出成形及制品质量的提高.     

反向挤压7075/SiCp复合材料中SiC颗粒 断裂失效的数值模拟研究

应用Deform-2D有限元软件,在挤压温度为300~450 ℃,挤压比为4~64,挤压速度为2~30 mm/s时,对喷射沉积7075/SiCp复合材料反向挤压过程中,SiC颗粒的转动与断裂失效进行了数值模拟。研究结果表明：在反向挤压过程中,SiC颗粒的转动是由基体合金的不均匀流动造成的;离中心轴线越远,流动不均匀性及SiC颗粒的转动倾向越大;基体的流动不均匀程度随挤压速度的增大和挤压比的升高而增大。在反向挤压过程中,SiC颗粒随基体运动不协调时,在较大应力作用下易发生断裂失效,且坯料外侧断裂失效分数大;当挤压比为4~25,挤压温度为400~450 ℃时,SiC颗粒断裂失效分数较小。当挤压比为16时,不同挤压温度下合理的挤压速度范围应控制在t=400 ℃、v<30 mm/s,t=425 ℃、v<20 mm/s,t=450 ℃、v<5 mm/s。     

等径道角挤压对Mg-6Al合金性能的影响

为了优化铸态Mg-6Al合金等径道角挤压的工艺参数,通过等径道角挤压实验研究了工艺参数对其性能的影响.研究表明:等径道角挤压可大幅度提高Mg-6Al合金坯料的力学性能.当Mg-6Al合金挤压1道次至4道次后,其力学性能提高较大,微观组织明显细化.随挤压温度从260℃升高至300℃,被挤压坯料的力学性能先提高后降低.当挤压路径为路径B,挤压道次为4道次,挤压温度为300℃时,Mg-6Al合金的力学性能最高,其抗拉强度为308.2 MPa,延伸率达到30.6%.     

Influence of the process setup on the microstructure and mechanical properties evolution in porthole die extrusion

Industrial needs are becoming always more complex pushed by an ever more demanding market and an increasingly fierce competition. Innovation and new products are the way forward if customers’ attention has to be captured. On this direction, extrusion processes can be properly designed for the manufacture of complex shape parts. Furthermore, taking into account the current requirements related to the reduction of weights and volumes for fuel saving in the automotive field, the production of components with thinner thickness is increasingly on demand. Therefore, the process complexities have been growing up but, at the same time, companies have to assure quality and productivity in a more and more competitive scenario.In this work, porthole die extrusion was investigated and an “I” shaped section with the welding line in the middle of the tongue was the chosen profile. Different extrusion conditions were experimentally analyzed by changing both the profile thickness and the ram velocity; the impact of these variables on the product quality was evaluated by microstructural observations and tensile tests. The aluminum alloy, AA6060, was the investigated material. The die optimization was carried out by numerical analyses for homogenizing the flow velocity at the die exit; the simulations were also utilized for locally calculate the pressure and temperature distributions in the die and at the exit of the bearing zone for a better explanation of the experimental evidences.A wide discussion on the obtained results is here reported.     

铝合金异形波导管的热挤压

论述了Ｐ４Ａ１４８３－４型铝合金异形波导管的挤压模设计和挤压工艺选择；提出了采用分流组合模挤压工艺制造复杂形状的异形波导管。     

铜银合金连续挤压过程中腔体结构参数影响

本文基于刚粘塑性有限元理论,运用DEFORM3D软件对不同腔体参数(模口宽度、堵头高度和堵头截面形状)下的铜银合金连续挤压过程进行了模拟,重点分析了其对初始阶段应变、流速的影响。模拟结果表明,较小的模口宽度和较大的堵头高度有利于挤压成形和提高产品质量,而选择合理的堵头纵截面形状也能显著改善金属流动。这对腔体的优化设计有一定的指导作用。     

Effect of extrusion stem speed on extrusion process for a hollow aluminum profile

Extrusion stem speed is one of important process parameters during aluminum profile extrusion, which directly influences the profile quality and choice of extrusion equipments. In this paper, the extrusion process of a thin-walled hollow aluminum profile was simulated by means of the HyperXtrude commercial software. Through a serial of numerical simulation, the effects of stem speed on extrusion process, such as metal flow behavior at die exit, temperature distribution, extrusion force, and welding pressure, have been investigated. The numerical results showed that there existed an optimum value of stem speed for flow velocity distribution. With the increasing stem speed, the temperature of the extrudate and required extrusion force increased, and the welding quality of extrudate would be improved. Through comprehensive comparison and analysis, the appropriate stem speed could be determined for practical extrusion production. Thus, the research results could give effective guideline for determining initial billet and die temperature and choosing the proper extrusion press in aluminum profile industry.     

Extrusion of AI–Zn–Mg–Cu–Zr alloys

Abstract

Four aluminium alloys of different zinc/magnesium ratio have been studied under various extrusion conditions. The alloys were cast in steel book moulds and subjected to initial thermomechanical treatments. Studies were made of hot extrusions and cold hydrostatic extrusions and in each case the changes in the extrusion parameters were analysed. An attempt has been made to explain some of the extrusion defects which appeared in various extruded sections. The extrusion speed was found to be crucial, since sections developed surface cracks at higher speeds. The extrusion speed was also found to vary inversely with the extrusion ratio, with higher speeds at low ratios. A well defined solute–depleted weld zone was observed on each of the four faces of a square tube extruded using a porthole die. Thermal treatment was not found to improve this weak weld zone. Tubes extruded using a floating-mandrel die withstood pressure testing up to 550 MPa.

MST/43     

7075铝合金高速搅拌摩擦焊材料流动行为及性能研究

目的 针对7075–O铝合金高焊速、高转速搅拌摩擦焊接缺陷多、质量差等问题,研究焊接接头材料流动对焊缝性能的影响。方法 选用焊接速度1 000 mm/min,搅拌转速分别为1 000、1 200、1 600、1 700 r/min的条件对7075–O铝合金板进行搅拌摩擦焊接,分析不同焊接工艺参数下焊接接头的显微组织及力学性能。同时,利用Fluent软件模拟7075–O铝合金搅拌摩擦焊接过程中的材料流动场分布,分析焊接材料流动与缺陷形成的关系。结果 利用7075–O铝合金三维流动模型,预测出高焊速条件下焊缝前进侧形成一个低压区,孔洞等缺陷易出现在此区域,数值模拟预测与试验结果吻合。在高焊接速度1 000 mm/min、焊接转速1 200 r/min时,焊缝表面光滑平整,焊核区域的硬度分布更加均匀。结论 随着搅拌转速从1 000 r/min增大到1 700 r/min,热输入量逐渐增大,孔洞缺陷由隧道型孔洞转变为不连续的小孔。同时,随着搅拌转速的增大,焊缝高硬度区域的宽度先增大而后降低。当搅拌转速为1 200 r/min时得到了优质的焊接接头,焊缝焊核区硬度分布均匀,硬度值最高为176HV。     

Numerical investigation of an arc inlet structure extrusion die for large hollow sections

This paper aims to improve the working life of extrusion dies by optimal structure design, which plays an important role in mass production. First, an arc-shaped inlet die structure for an aluminum large-hollow-section profile was developed. Second, a three-dimensional finite-element model of the porthole extrusion process was established using an arbitrary Lagrangian-Eulerian method. Third, the comparison of the formability was analyzed and discussed, including the diversity of extrusion forces and uniformity properties between the proposed design and two traditional design schemes using the same extrusion process. A group of square-profile extrusion dies was used to set up a L16_4_3 orthogonal experimental scheme, considering the side length of profiles, L, with four levels, 110, 100, 90, and 80 mm; inlet angles, α, of the porthole bridge of 0°, 10°, 20°, and 30°; and profile wall thicknesses, t, of 1, 1.5, 2, and 2.5 mm. The results of the orthogonal tests were similar to those of the actual production die model. Two different analysis models reached the same conclusion: the inlet angle or the arc inlet structure has a small effect on the metal flow and the forming distribution, but the arc inlet structure can alleviate the stress load of the dies. The die testing and production validation results indicate that the novel structural design of the arc inlet die will have a long working life.