Mathematical model of determination of die bearing length in design of aluminum profile extrusion die

Based on the finite element simulation of profile extrusion process, the effect of local extrusion ratio, die bearing area and the distance between extrusion cylindrical center and local die orfice center on mental flow velocity was investigated. The laws of deformed metal flow on profile extrusion process were obtained. The smaller the local extrusion ratio, the faster the metal flow velocity; the smaller the area of die bearing, the faster the metal flow velocity; the smaller the distance of position of local die orifice(the closer the distance of position of local die orifice from extrusion cylindrical axis), the faster the metal flow velocity. The effect of main parameters of die structure on metal flow velocity was integrated and the mathematical model of determination of die bearing length in design of aluminum profile extrusion die was proposed. The calculated results with proposed model were well compared with the experimental results. The proposed model can be applied to determine die bearing length in design of aluminum profile extrusion die.

Influence of dynamic recrystallization on microstructure and mechanical properties of welding zone in Al-Mg-Si aluminum profile during porthole die extrusion

The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morphology was observed by means of electron backscatter diffraction(EBSD)technology.The results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain rate.In contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain rates.The microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix zones.The grain size in the welding zone was smaller than that in the matrix zone due to lower DRX fraction.The decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.

Non-steady FE analysis on porthole dies extrusion of aluminum harmonica-shaped tube

According to the rigid-viscoplasticity finite element method,the porthole die extrusion process of an aluminum harmonica-shaped tube was successfully simulated based on software Deform-3D. The distribution of stress field,effective strain field,velocity field and temperature field during the extrusion process were discussed and the metal flow in welding extrusion was analyzed. The simulation results show that the material flow velocities in the bearing exit are non-uniform with the originally designed die and the forepart of the profile is not neat or even. Aiming at solving this problem,the modification method of die structure was improved. The result shows that the uniform material flow velocities in the die exit and a perfect extruded are obtained by modification bearing length.

Structure optimization of porthole die based on aluminum profile extrusion process numerical simulation

Porthole die extrusion method is used to produce hollow aluminum profile. Due to the complexity of the porthole die structure and the material flow, it is very difficult to get ideal profile products with the firstly designed die structure. Finite volume numerical simulation was used to analyze the extrusion process of a hollow profile with porthole die and the problem of non-uniform material flow was found. Optimization was made to the originally designed die to solve the problem. Lower load, reasonable seaming location and even extruded forepart with uniform material flow in the optimized die extrusion were obtained. Guidelines to porthole die design were given and it is also concluded that finite volume method with Eulerian description avoids mesh regeneration and is suitable to numerical simulation of severe deformation processes, such as profile extrusion.

Key technologies of "zero die trial" design system for aluminum profile extrusion

Aluminum alloy profile parts are widely used in the fields of aviation,equipmen t,automobile and ornamental industries. The construction method for “zero die trial” intelligent design system of aluminum extrusion die was studied based on KBE idea. An object-oriented knowledge language AEKL(Aluminum Extrusion Knowl edge Language) was developed to construct intelligent knowledge model with three methods,frame,parameters and rules. On the aspect of knowledge reasoning,cas e-based reasoning was employed in addition to traditional rule-based reasoning method. API provided by CAD platform was used in geometry disposal. Finally,th e corresponding prototyping system was established and an design example was sho wn.

Effect of process parameters on sheath forming of continuous extrusion sheathing of aluminum

The effect of flow passage length in the die cavity and extrusion wheel velocity on the shape of aluminum sheath during the continuous extrusion sheathing process was analyzed by using finite element methods based on software DEFORM 3D and experimentally validated. The results show that by increasing the flow passage length, the velocity of metal at the cross-section of sheath tends toward uniformity, the values of the bending angles of sheath gradually approach the ideal value of zero and the cross-section exhibits a better shape. The extrusion wheel velocity has negligible effects on the bending shape and cross-section of the sheath product when a long flow passage is used.

Extrusion force analysis of aluminum pipe fabricated by CASTEX using expansion combination die

To determine the extrusion force of pipe fabricated by continuous casting and extrusion (CASTEX) using an expansion combination die, the metallic expansion combination die was divided into diversion zone, expansion zone, flow dividing zone, welding chamber, and sizing zone, and the corresponding stress formulae in various zones were established using the slab method. The deformation zones of CASTEX groove were divided into liquid and semisolid zone, solid primary gripping zone, and solid gripping zone, and the formulae of pipe extrusion forces were established. Experiments were carried out on the self-designed CASTEX machine to obtain the aluminum pipe and measure its extrusion force using the expansion combination die. The experimental results of radial extrusion force for aluminum pipe are in good agreement with the calculated ones.

FEM simulation of aluminum extrusion process in porthole die with pockets

In order to investigate the effects of pockets in the porthole die on the metal flow,temperature at the die bearing exit and the extrusion load were contrasted with the traditional die design without the pockets in the lower die.Two different multi-hole porthole dies with and without pockets in lower die were designed.And the extrusion process was simulated based on the commercial software DEFORM-3D.The simulation results show that the pockets could be used to effectively adjust the metal flow and especially benefit to the metal flow under the legs.In addition,the maximum temperature at the die bearing and the peak extrusion load decrease,which indicates the possibility of increasing the extrusion speed and productivity.

Effects of process parameters and die geometry on longitudinal welds quality in aluminum porthole die extrusion process

By using the rigid-visco-plasticity finite element method, the welding process of aluminum porthole die extrusion to form a tube was simulated based on Deform-3D software. The welding chamber height （H）, back dimension of die leg （D）, process velocity and initial billet temperature were used in FE simulations so as to determine the conditions in which better longitudinal welding quality can be obtained. According to K criterion, the local welding parameters such as welding pressure, effective stress and welding path length on the welding plane are linked to longitudinal welds quality. Simulation turns out that pressure-to-effective stress ratio （ρ/σ） and welding path length （L） are the key factors affecting the welding quality, Higher welding chamber best and sharper die leg give better welding quality. When H=10 mm and D=0.4 mm, the longitudinal welds have the best quality. Higher process velocity decreases welds quality. The proper velocity is 10 mm/s for this simulation. In a certain range, higher temperature is beneficial to the longitudinal welds. It is found that both 450 and 465℃ can satisfy the requirements of the longitudinal welds.

Effect of die inlet geometry on extrusion of clover sections through curved dies:Upper bound analysis and experimental verification

The effect of die inlet and transition geometry on the extrusion loads and ~aaterial flow for extrusion of clover sections were investigated and presented both theoretically and experimentally. For this purpose, four different die geometries including straight tapered and cosine transition profile and each of them having round and clover inlet geometries were chosen. In the experimental study, commercially pure lead was used because of its hot forming characteristic at room temperature. A newly kinematical admissible velocity field to analyze different profiles of extrusion dies of clover section from round bars was proposed by upper bound analysis. It is clear that the extrusion loads obtained from the theoretical analysis for various die inlet-die transition geometry combinations are in good agreement with the experimental results. Axis deviations of the parts which define the dimensional quality of the products were also investigated.

Forward hot extrusion forming process of 4-lobe aluminum alloy helical surface rotor

The 4-lobe aluminum alloy helical surface rotors are widely applied in industry,such as superchargers.Generally,the conventional manufacturing processes of aluminum alloy helical surface are time consuming and costly.To make the manufacturing processes more flexible and economical,the forward hot extrusion process is proposed to form the 4-lobe aluminum alloy helical surface rotors.In this work,we implement both simulations and experiments to the forming process of the helical surface,of which the material is 6063 aluminum alloy.The forward hot extrusion process is simulated with finite element method in DEFORM-3D.Based on the simulation method,the influences of different extrusion parameters,such as extrusion temperature,extrusion speed and extrusion ratio,on the extrusion process are studied.According to the numerical simulation results,the optimal case is chosen to carry out the experiment.Furthermore,the experimental results show that the surface is smooth;the toothed fill is full;the twist angle in the length direction is evenly distributed;the value of twist angle is roughly in line with the design angle,which is mainly due to the modified die structure,having a positive and significant effect on the increment of twist angle.Therefore,the twist angle has an increase of about 76%,which verifies the modified die structure.

Contrast of FEM and FVM in simulation of complex aluminum extrusion

Extrusion is the key technology to manufacture aluminum profiles and involves complicate metal deformation coupled with temperature changes. The choice of numerical technique plays an important role and is related to the accuracy and effectiveness of extrusion process analyses. In this paper, the extrusion processes of two complex aluminum profiles are simulated with FEM and FVM respectively. The merit and disadvantage of these two methods are analyzed. The finite element method exhibits higher calculation efficiency in the simulation of a lock catch extrusion process. However, due to frequent rezoning in simulation of complex extrusion process, sharp distortion of finite element mesh can decrease computational accuracy. Therefore the volume loss in FEM simulation is larger than that in FVM simulation by five percent. Based on Euler description, the finite volume method employs structured element mesh covering entire material flowing area, which makes it more robust in the simulation of complicate extrusion process. The deformation configuration with FVM is much smoother than that with FEM in the extrusion simulation of a thin-walled aluminum profile, although FVM requires more computation time.

KEY TECHNIQUES IN R&D OF OUT-SIZE EXTRUSION PRESS WITH OIL-DRIVEN DOUBLE ACTION

A modem design method, in which traditional design formulas are conjoined with numerical simulation and optimization, is successfully used to design the out-size extrusion flame precisely so that the press cost can be saved. A new technology used for decompressing by a multi-steps dynamical mode is put forward, which makes it possible to decompress the large flow-volume high-pressure oil in the main cylinders. In addition, a method for realizing the fixed mandrel process by hydraulic support is proposed and its control equation is established. Pre-tightening frame tests are carried out by over-operating pressure on 100 MN aluminium extrusion press with oil-driven double action, which is developed based on the above key techniques and is the largest press so far in the world, and the results show that the frame structure designed is reasonable and reliable, and the modem design method used is an useful tool for designing large and out-size heavy plastic forming machinery. The results of decompressing curve in main cylinder and noise inspection indicate that multi-steps dynamical mode for decompressing the large flow-volume high pressure oil is valid and reliable. Meanwhile, the fixed mandrel process is well realized based on the control equation. These key techniques have been used in the development of 125 MN aluminium extrusion press with oil-driven double action.

基于QForm-extrusion下的挤压模具模拟分析及结构优化

铝挤压过程中对于模具能否挤压出合格的型材,主要影响因素是型材截面各部分在稳定挤压过程中的流速,本文重点研究分析流速场,采用目前国内外专业用于挤压模具仿真软件QForm-extrusion,对挤压模具进行模拟分析和验证,观察铝合金在模具的流动情况,能够提前发现模具设计中的缺陷,从而优化模具设计方案。本文的研究方法大大缩短了产品的交货期,提高了产品的合格率,具有一定的实际应用价值。

聚合物三腔微管挤出口模结构对胀大变形的影响

聚合物熔体的模内流动状态与模外胀大变形直接影响微挤出制品的成型质量。文中基于Carreau模型,采用数值模拟方法,研究了聚合物三腔微管挤出过程中口模壁厚差与空心度结构特征对胀大变形行为的影响。结果表明,影响挤出胀大变形程度的关键因素是口模出口附近的轴向速度分布;内外壁厚差会导致较大壁厚位置处对应的型坯厚度增大,而较小壁厚位置处的型坯厚度减小,壁厚差变化对薄壁区域壁厚变形影响较大,达到91.4%;空心度减小能提升口模出口附近轴向速度分布均匀性,减小了70.1%的变形程度;基于胀大变形规律逆向补偿设计了口模形状与尺寸,明显改善了制品成型质量。研究结果对聚合物多腔微管的口模结构优化设计具有理论意义与工程应用价值。

铝合金型材挤压弯曲一体化成形技术研究进展

相比于直型材,铝合金弯曲型材更适用于日益复杂的部件形状并能更好地满足轻量化需求,具有提升部件结构强度和刚度、节约空间及增加工业设计自由度等优点,在汽车、高铁和航空航天等领域具有广泛用途。相较于传统冷弯成形技术,挤压弯曲一体化成形技术在生产弯曲型材方面具有流程短、精度高、缺陷少等优点,因而受到广泛关注。重点综述了基于外部弯曲装置和材料差速流动的挤压弯曲一体化成形技术的研究进展,分析并总结了不同挤压弯曲一体化成形技术的原理及发展现状,对比了不同挤压弯曲一体化成形技术的优缺点,最后展望未来发展趋势及其研究方向。

铝合金挤压型材的拉伸失效行为研究

为了研究挤压速度、预热温度、挤压角度等对铝合金性能的影响,通过熔炼、差压铸造、挤压制备出铝合金型材,用万能试验机完成双向拉伸试验,用扫描电子显微镜观察显微组织,分析差压铸造铝合金经挤压后的拉伸失效行为。结果表明:双向拉伸后,铝合金型材出现较严重的变形,挤压角度为90°时,铝合金挤压型材不易拉断;挤压速度为1.5 mm/s时拉伸损伤概率更低;预热温度为250℃时拉伸后韧窝更密集,不易脆性断裂。

铸铝转子端环气孔的改善及优化

三相异步电机被广泛运用于新能源汽车行业,但铸铝转子端环处的气孔造成了电机的噪声增加、强度降低、电导率降低,影响了电机的效率。为了有效减少铸铝转子端环气孔的产生,采用控制变量法及正交分析法对现有的压铸工艺参数进行了工艺优化,并提出了一种消除端环气孔的自动挤压装置。结果表明:当锤头路径相同时,压力铸铝过程中,压力的影响最大,高速时的速度影响次之,低速的速度影响最小,且工艺优化后的压铸工艺参数使铸铝转子的合格率提升至74%,且端环挤压可有效解决端环气孔问题,抗拉性能提升了37.5%,电导率提高了12.4%,为消除铸铝转子端环气孔提供了新方案,有望进一步提升铸铝转子品质。

铝合金型材挤压过程能耗优化的研究现状

铝合金挤压型材广泛用于汽车领域。在推动绿色发展的战略背景下,铝合金型材挤压过程的能耗优化问题越来越受到关注。论述了铝合金型材挤压过程能耗优化的重要性,介绍了主要影响因素,并从挤压机能耗和挤压成型能耗两方面分析了铝合金型材挤压过程能耗优化的研究现状。

5E61铝合金壁板型材挤压过程的模拟和试验研究

为研究5E61铝合金壁板型材挤压过程变形的规律,本文通过热模拟压缩试验建立了5E61铝合金本构模型,确定了动态再结晶动力学模型中的相关参数。研究结果表明,模具结构和挤压工艺共同决定了热挤压成形过程中金属的变形,其中模具结构对型材挤出速度场的影响最大,挤压工艺影响不明显,模具结构对型材截面的组织影响较小,型材挤出温度场和应变场共同决定型材截面组织的演变;模具温度和挤出速度对料头形状、型材截面温度场及动态再结晶体积分数的影响最大,挤压筒的影响次之,铸锭温度的影响最小。