微通道扁管挤压成形模拟及焊合质量的预测

采用刚塑性有限元软件DEFORM-3D对微通道扁管的挤压成形进行数值模拟,得到两种分流模具挤压微通道扁管时焊合面上静水应力、等效应力和金属速度的分布以及变化规律。利用Donati提出的K参数法对两种模具的焊合面焊合质量进行预测对比,得到平面模和球面模的焊合面焊合质量指标Kad值分别为154.7和196.0,表明球面模挤压得到的扁管焊合质量优于平面模。通过实验测量两种模具挤压得到扁管的爆破压力分别为18.5MPa和26.0MPa,表明球面模挤压扁管的承压能力高于平面模,并进一步验证了预测结果。     

铜铝复合板等通道转角挤压模具设计及数值模拟

为了深入研究通过挤压成形制备铜铝复合板的工艺方法,利用等通道转角挤压(ECAP)方法工艺与设备简单的优点,设计了一套可拆卸、可更换模具转角的实验模具方案。利用HyperXtrude对铜铝复合板的等通道转角挤压过程进行数值模拟,分别选取模具转角为0°,15°,30°,45°和60°的5组方案进行了模拟与分析,对铜铝复合板在等通道转角挤压过程中的压力、应力场张量、速度场分布进行了探讨。结果表明:转角从0°变化至60°,压力从186.1 MPa下降至141.5 MPa;当转角为45°时,金属流动速度最为均匀。     

伞形筒热挤压工艺及模具设计

利用数值模拟技术对伞形筒挤压工艺参数和挤压模具进行设计。建立有限元模型,采用DEFORM软件对其成形过程进行数值模拟,分析了挤压温度和挤压速度对挤压力的影响,并从模具寿命方面考虑设计了模具预热温度等成形工艺参数。结果表明,采用热挤压模具在300 T液压机上能够生产出合格的伞形筒工件;毛坯加热温度为930±10℃,模具预热温度为250±10℃,挤压速度为30 mm/s,挤压性能较好,挤压件符合设计要求。     

镁合金射钉枪端盖等温体积成形的数值模拟

针对射钉枪端盖零件,设计了等温挤压成形工艺和等温挤压试验模具.利用DEFORM-3D对成形过程进行数值模拟,预测了射钉枪端盖零件成形力为90 kN以及成形过程分为5个阶段.采用YAW-500 kN微机控制电液伺服压力试验机进行挤压试验,试验证明所没计的成形方案合理町行,同时也验证了数值模拟分析的正确性.     

镁合金扩管挤压过程的有限元数值模拟

利用DEFORM-3D软件对AZ31镁合金扩管挤压成形过程进行了数值模拟,分析了不同温度和不同模具角度对成形挤压力的影响.结果表明,温度越高,挤压力越小;在给定的工艺参数下,得到了最佳模具角度,使得挤压力最小.数值模拟计算出的挤压力可以为挤压设备的选择提供依据.选取合适的挤压温度和最佳模具角度进行了挤压模拟,得到了挤压过程中等效应力场、等效应变场等的变化过程和分布规律,发现内外模具圆角处的应力应变值最大.分析了产生的原因,这能为模具优化提供参考.     

镁合金射钉枪端盖等温体积成形试验研究

以射钉枪端盖零件为例,设计了等温挤压成形工艺及试验模具。利用DEFORM-3D对成形进行了数值模拟,预测了零件成形力和设计了成形过程阶段。在YAW-500kN微机控制电液伺服压力试验机上进行挤压试验,试验证明,设计的成形方案合理可行。同时验证了数值模拟分析的正确性。     

AZ31D刀把等温挤压成形试验与数值模拟

针对电动螺丝刀刀把零件,设计了等温挤压成形工艺和等温挤压试验模具。并利用Deform-3D对成形过程进行数值模拟,预测了电动螺丝刀刀把零件成形力为250 kN。采用YAW-500 kN微机控制电液伺服压力试验机进行挤压试验,试验证明所设计的成形方案合理可行,同时也验证了数值模拟分析的正确性。     

镁合金电动螺丝刀刀把等温挤压成形研究

针对镁合金电动螺丝刀刀把零件,设计了等温挤压成形工艺和等温挤压试验模具;利用DEFORM-3D对成形过程进行数值模拟,预测了电动螺丝刀刀把零件成形力为250kN.采用YAW-500kN微机控制电液伺服压力试验机进行挤压试验,试验证明所设计的成形方案合理可行,同时也验证了数值模拟分析的正确性.     

亚热精密成形过程模具磨损的数值模拟研究

采用数值模拟技术分析了亚热挤压成形阶段坯料及模具上的参量变化。基于修正的磨损模型,将其引入到有限元数值模拟软件中,对亚热挤压过程中模具磨损量的变化情况进行了分析,得到了不同变形阶段的瞬时磨损曲线及一次成形结束时的综合磨损曲线。利用研究结果对模具的磨损寿命进行了预测,与实际情况对比,两者吻合较好。     

活塞温挤压成形工艺分析及其成形过程数值模拟

分析CA6DL型活塞温挤压成形工艺,建立活塞温挤压成形的三维塑性有限元模型,通过对其成形过程进行数值模拟,获得了成形全过程的材料流动规律、模具充填、材料内部应变分布以及行程载荷曲线等,通过仿真模拟可知,活塞裙部充填较为困难.为活塞温挤压成形工艺与模具优化设计提供理论指导,在此基础上设计活塞温挤压成形工艺和模具结构.     

A physical simulation of longitudinal seam welding in micro channel tube extrusion

Micro channel tube is a newly developed type of aluminum profiles with sub-millimeter-diameter ports in the cross-section designed for heat transfer enhancement. Micro channel tube is formed with porthole extrusion die, and the longitudinal seam welding problem is the key issue related to both the design of the delicate mandrel in the extrusion die and the pressure bearing capacity of the tube. This paper proposes a novel method to evaluate the seam welding strength of the micro channel tube at the stage of extrusion die design. First, a finite element (FE) simulation of the tube extrusion process is performed for the seam welding conditions in the die chamber and effect of the welding chamber height on hydrostatic pressure. Then, a thermo-mechanical experiment is carried out for a quantitative relationship between the welding strength and the weld condition parameters. Combining this relationship to the numerical results, the welding strength under different die design can be evaluated. Pressure bearing tests on the tube prove the reliability of this evaluation method. This study quantitatively connects the seam welding strength of the profile to the extrusion die parameters, which is helpful for optimizing the design of the extrusion process.     

大型无缝铝管材固定针挤压工艺研究

介绍了几种无缝铝管材挤压工艺,采用理论分析、数值模拟与实验研究相结合的方法,对大型无缝铝管材固定针挤压工艺进行了研究。分析了固定针挤压时穿孔针的受力情况,建立了穿孔针受力的力学计算公式,得出了穿孔油缸系统压力变化公式。采用有限元数值模拟的方法,对无缝铝管材固定针挤压工艺进行了数值模拟,揭示了无缝铝管材挤压过程中穿孔针上拉力与行程曲线的变化规律,据此,提出了实现无缝铝管材固定针挤压工艺的技术路线。研究结果在55 MN油压双动短行程铝挤压机上进行了实验验证。     

异型钢管辊挤成型过程的有限元模拟

利用非线性有限元分析软件MSC.Marc对方形异型钢管的无芯棒辊挤成型过程进行了有限元分析,得到了成型过程中应力与变形的分布与变化以及成型后异型管的结构形状。实验结果验证了有限元分析的正确性。研究结果为生产提供了有益的依据。     

Prediction of welding pressure in the non-steady state porthole die extrusion of Al7003 tubes

This paper describes a numerical analysis of non-steady state porthole die extrusion, which is useful for manufacturing long tubes with a hollow section. Materials divided through several portholes are gathered within a chamber and are then welded under high pressure. This weldability classifies the quality of tube products and is affected by process variables and die shapes. However, porthole die extrusion has been executed based on the experience of experts, due to the complicated die assembly and the complexity of metal flow. To better assist the design of die and to obtain improvement of productivity, non-steady 3D FE simulation for porthole die extrusion is required. Therefore, the objective of this study is to analyze the behavior of metal flow and to determine the welding pressure of hot extrusion products according to various billet temperatures, bearing length, and tube thickness by FE analysis. The results of FE analysis are compared with those of experiments.     

Damage prediction for magnesium matrix composites formed by liquid-solid extrusion process based on finite element simulation

A damage prediction method based on FE simulation was proposed to predict the occurrence of hot shortness cracks and surface cracks in liquid-solid extrusion process. This method integrated the critical temperature criterion and Cockcroft &; Latham ductile damage model, which were used to predict the initiation of hot shortness cracks and surface cracks of products, respectively. A coupling simulation of deformation with heat transfer as well as ductile damage was carried out to investigate the effect of extrusion temperature and extrusion speed on the damage behavior of C_sf/AZ91D composites. It is concluded that the semisolid zone moves gradually toward deformation zone with the punch descending. The amplitude of the temperature rise at the exit of die from the initial billet temperature increases with the increase of extrusion speed during steady-state extrusion at a given punch displacement. In order to prevent the surface temperature of products beyond the incipient melting temperature of composites, the critical extrusion speed is decreased with the increase of extrusion temperature, otherwise the hot shortness cracks will occur. The maximum damage values increase with increasing extrusion speed or extrusion temperature. Theoretical results obtained by the Deform?-2D simulation agree well with the experiments.     

1050铝合金扭转挤压加工的3D有限元分析(英文)

研究了扭转挤压做为一种大塑性变形加工技术的可行性,并将其与普通的正挤压进行比较。在室温下对AA1050铝合金成功进行了扭转挤压和正挤压。采用商用有限元软件ABAQUS/Explicit模拟挤压过程。结果表明,在扭转挤压中,所需的载荷要比正挤压所需的小。有限元分析结果表明,在扭转挤压中,试样承受了较高的等效塑性应变,在挤压的最后阶段扭转挤压试样中的应变分布较之正挤压更为平滑,均匀。     

FE analysis of metal flow and weld seam formation in a porthole die during the extrusion of a magnesium alloy into a square tube and the effect of ram speed on weld strength

The present communication concerns a detailed analysis of metal flow into a porthole extrusion die to produce a thin-walled square magnesium tube by means of three-dimensional FE simulation in both the transient state and steady state. The research was aimed to get an insight into the longitudinal weld seam formation during extrusion through porthole dies and to evaluate the factors determining the quality of the weld seams. FE simulation revealed distinctive stages at the beginning of an extrusion cycle, corresponding to the changes in extrusion pressure during the process. It showed that the commonly observed defect at the extrudate head was due to entrapped air under the bridges in the upper part of the welding chamber. The dead metal zones existed at the corners between the container and die face and between the bottom and sidewall of the welding chamber. Because of the friction at the die bearing, the metal flow through the die bearing resembled laminar flow. Only the virgin metal from the interior of the billet flowed along the bridges and formed the welding seams. As ram speed increased, the mean stresses and temperatures on the welding plane in the welding chamber increased, which was reflected in the increases in extrusion pressure and extrudate temperature, being beneficial to the solid-state bonding at the weld seams. Tensile tests confirmed that extrusion at a higher ram speed led to enhanced transverse tensile strength and strain of the extruded square tube, as a result of improved bonding at the longitudinal weld seams.     

汽车差速器壳类锻件精密挤压工艺研究

差速器壳是汽车中的关键零件之一,形状复杂,采用传统开式模锻工艺生产,锻造成形和质量保证难度大。通过对3种差速器壳成形过程进行有限元分析,对工艺参数及模具结构进行优化设计,设计了3种差速器壳零件毛坯的精密热挤压模块化生产工艺方案。实际生产结果显示,锻件质量良好,与有限元分析结果吻合,工艺方案合理,可实现高质量、低成本的绿色生产。     

钛合金实心锭穿孔挤压穿孔过程有限元分析

探明实心锭穿孔过程的材料流动和穿透断裂行为对高性能优质无缝管材的实心锭穿孔挤压推广应用具有重要意义。以直径200 mm实心锭为原料,穿孔挤压成直径80 mm、壁厚10 mm的钛合金管材为研究对象,基于DEFORM-2D软件环境,建立了能够描述材料流动和穿透断裂行为的实心锭穿孔挤压穿孔过程的热力耦合有限元模型。研究分析了2种形状穿孔冲头的穿孔过程。结果表明:穿孔初始阶段变形行为类似正挤压,随后材料反向流动,堵头去掉前都是反挤压变形;正挤压变形下穿孔力迅速上升,上升至稳定值后开始反挤变形,去掉堵头后的穿透断裂阶段穿孔力迅速下降;采用圆柱形穿孔冲头情况下反挤时穿孔力变化幅度不大,而采用瓶形穿孔冲头情况下的穿孔力稳定一段时间后再次显著增加,瓶形穿孔冲头的穿孔力远大于圆柱形穿孔冲头的穿孔力;穿透断裂阶段,圆柱形穿孔冲头下的断裂行为类似于冲裁断裂,而瓶形穿孔冲头下的约束增强,其断裂面近似呈L型。     

金属挤压机的定针方式及控制

本文对卧式双动挤压机穿孔针的机械和液压定针结构进行了研究,分析了挤压过程中两种定针结构的力传递过程和作用在穿孔针上的受力情况.机械定针系统结构庞大,调节复杂,液压定针系统结构简单,调节简便.在挤压过程中液压定针系统可以随时改变和控制穿孔针与模具孔定径带的位置,从而挤压生产截面比较复杂的无缝管材.液压定针系统的工作过程由电液控制系统通过对压力、流量和位置的控制完成.