一种弯制大曲率半径的L型铝型材成型装置的研究与设计

对半径大于400 mm大曲率半径弧线件均采用专用拉弯设备才能生产,成本高,设备适应性差.为了解决这些难题,设计了一种大曲率半径L型铝型材拉弧成型装置.将模具的成形部分做成全封闭结构,同时改进进料系统,设计了与之配套的夹具.设计的模具可将L型铝型材弯制成所需角度的大圆弧,弯制的圆弧流畅、圆滑、无折皱.     

焊接结构与设计

20092192复杂闭口截面冷弯型钢的成型及焊接工艺设计/艾正青…//焊管.-2008,31(6):54~56闭口截面冷弯型钢与开口截面冷弯型钢相比,截面形状复杂且一般不对称,因而在焊接质量控制、尺寸控制以及成型设备等方面都存在很大的不同。以50钢门框型材产品设计为例,介绍了复杂封闭截面型钢常用的成型方式和焊接方式,分析了成型工艺对其焊接质量的影响,提出了在制定成型工艺时应注意的事项。实际生产证明,选用的50钢门框型材的成型工艺和焊接工艺合理可靠,成型和焊接质量稳定。图5参7焊接结构与设计     

焊接结构与设计

20092192复杂闭口截面冷弯型钢的成型及焊接工艺设计/艾正青…//焊管.-2008,31(6):54~56闭口截面冷弯型钢与开口截面冷弯型钢相比,截面形状复杂且一般不对称,因而在焊接质量控制、尺寸控制以及成型设备等方面都存在很大的不同。以50钢门框型材产品设计为例,介绍了复杂封闭截面型钢常用的成型方式和焊接方式,分析了成型工艺对其焊接质量的影响,提出了在制定成型工艺时应注意的事项。实际生产证明,选用的50钢门框型材的成型工艺和焊接工艺合理可靠,成型和焊接质量稳定。图5参7焊接结构与设计     

冷弯成型理论与工艺技术的发展

冷弯型钢以其节能环保的特征被人们普遍使用,用更少的钢材使用量来完成所需达到的指定载荷,不再完全依靠于增加板材的使用量或提高材料的力学性能来满足载荷的要求,而是通过改变型钢产品的截面形状来提高型钢的力学性能。文章主要介绍冷弯成型的理论分析方法及其新兴的成型技术。其中有在传统冷弯型钢机组的基础上优化板材,通过预加热的方法改善板材的塑形来改善冷弯型钢的技术,如:局部加热成型技术和热冷弯成型技术。以及增加新的截面形状,生产变截面型钢的三维冷弯成型工艺、分枝冷弯成型技术、非等厚冷弯成型技术等。     

大尺寸封闭截面铝型材拉弯工艺研究

本文以数值模拟为手段 ,利用大型商业化有限元软件Pam Stamp ,针对铝型材框架式车身生产中的关键技术———铝型材高精度弯曲成形进行了深入系统的研究 ,模拟了大尺寸封闭截面铝型材AA60 82 (T1状态 )在不同弯曲半径下的拉弯成形过程。研究结果表明 ,铝型材拉弯成形极限主要受脱模、起皱及壁厚减薄的限制 ,而成形精度主要受回弹和截面变形的影响。截面形状、弯曲半径和拉伸量是铝型材拉弯工艺中的 3个重要参数 ,确定正确的拉伸量是拉弯工艺成败的关键。文章通过对计算结果的分析 ,提出了上限拉伸量和下限拉伸量及相应的确定方法 ,并给出了铝型材拉弯工艺中拉伸量的取值原则     

铝型材拉弯成形工艺稳健性优化

以截面为L形状的铝型材为对象,以拉弯件曲率半径为质量目标,基于数值仿真技术和稳健优化技术获取铝型材拉弯成形的优化工艺参数。借助数值仿真技术,采用试验设计方法查明了铝型材拉弯过程关键工艺参数,并且运用随机仿真方法完成了铝型材拉弯成形的最优工艺求解。研究结果表明:影响铝型材拉弯件曲率半径的敏感因素依次为补拉量、预拉量、摩擦条件;所建立的反映关键材料、工艺参数与拉弯件曲率半径之间的响应面方程具有较高的精度;在材料参数和摩擦条件为随机波动的前提下,通过工艺稳健优化方法获得了型材拉弯件可控工艺参数最优解。     

L型截面铝型材拉弯成形截面畸变缺陷控制研究

以某轨道车辆L型截面铝型材构件为研究对象,利用数值模拟技术分析了L型截面铝型材拉弯成形中常见截面畸变缺陷的成因,研究了模具结构参数对截面变形的影响规律,提出相应截面畸变缺陷的控制措施,并通过试验进行了验证。结果表明:L型截面铝型材拉弯成形主要截面畸变缺陷为立边倾斜和横边塌陷;立边倾斜缺陷主要因挡板间隙不合理引起,优化挡板间隙能够有效控制立边倾斜缺陷;横边塌陷主要因拉弯过程中立边收缩引起,基于相应位置的立边收缩量,通过减小拉弯模具支撑面的深度能够有效控制横边塌陷缺陷。     

有限元法模拟分析比较变截面U型材辊弯成型的立辊成型和平辊成型

利用有限元分析通用软件MSC.Marc对变截面U型材辊弯成型进行仿真模拟分析。本文对变截面辊弯成型仿真采用轧辊轴向加工技术(代替法向加工技术),对角度连续变化的变截面U型材分别进行立辊加工和平辊加工成型模拟分析。得出结论揭示了平辊加工和立辊加工对变截面型材在90°折弯变形时产生的影响,对实际生产具有一定的指导意义和参考价值。     

塑料包覆铝型材拉伸弯曲实验研究

针对轿车用复杂截面PVC塑料包覆铝型材密封条的三维拉弯成形,采用控制拉伸量的方法,通过选择合理的预拉量、恰当的成形模具截面及型材间填充物,对该截面型材进行了平面和垂直拉弯成形实验,得到了该型材平面和垂直拉弯的半径回弹量。结果显示,垂直拉弯回弹量是平面回弹量的1倍多,实验结果为研制该型材及同类产品拉弯工装模具和工艺参数选择,提供了依据。     

等离子弧金属快速成型设备控制系统设计

等离子电弧的弧柱温度高于普通电弧焊的两倍,且电弧发散非常小,等离子弧焊接时热影响区非常小,所以利用其进行零件制造时的成型精度高于其他电弧快速成型方法,并且不存在激光、电子束设备造价和使用费用高的缺陷,因此利用等离子弧作为热源进行快速成型制造成为研究热点。根据金属快速成型的主要特点和工艺流程,设计了等离子弧金属快速成型设备控制系统,该控制系统的控制核心为CP1H-PLC,配备了MT8-070i H3触摸屏、OMRON MY2N-J中间继电器单元。采用该设备进行实验,在合适的工艺条件下,成型件达到设计要求,证明该控制系统工作可靠、性能稳定。分析试验结果,初步掌握等离子弧金属快速成型工艺参数。     

挤出成形法制备多孔SiC陶瓷工艺研究

设计了不同孔径、不同形状的多孔蜂窝结构,对挤出浆料组成配方和挤出成形工艺进行了优化,采用挤出成形法制备了蜂窝多孔SiC陶瓷坯体,并通过反应烧结制备了蜂窝多孔SiC陶瓷,研究了挤出压力、速率等工艺参数对蜂窝多孔SiC陶瓷坯体质量的影响,以及反应烧结温度、排硅时间等对蜂窝多孔SiC陶瓷密度、强度等性能的影响。结果表明:合适的挤出压力、挤出速率有助于确保多孔陶瓷坯体的成形和具有一定的强度;反应烧结后排硅时间在0.5h时多孔SiC陶瓷三点弯曲强度最高,为25.67MPa,制备的多孔SiC陶瓷/耐热钢基复合材料陶瓷分布均匀,界面结合良好。     

微小塑料铰链模内装配注射模设计

分析了采用模内装配技术注射成型微小塑料铰链的工艺特点及其所面临的难题,通过优化微小塑料铰链的结构,合理安排塑件的成型顺序以及塑件的浇口位置和分型面,提出了一种能够有效避免模具微细型芯在聚合物熔体高压作用下发生弯曲变形的成型方案。依据这一成型方案和实验室的设备条件,设计了一副能够在单料筒微注塑机上使用的模内装配技术注射成型微小塑料铰链的模具,不仅解决了微小塑料铰链的塑件之间难以产生运动间隙的问题,而且降低了对成型设备的要求。     

Fabrication of metal matrix composites by metal injection molding—A review

Metal injection molding (MIM) is a near net-shape manufacturing technology that is capable of mass production of complex parts cost-effectively. The unique features of the process make it an attractive route for the fabrication of metal matrix composite materials. In this paper, the status of the research and development in fabricating metal matrix composites by MIM is reviewed, with a major focus on material systems, fabrication methods, resulting material properties and microstructures. Also, limitations and needs of the technique in composite fabrication are presented in the literature. The full potential of MIM process for fabricating metal matrix composites is yet to be explored.     

Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.     

Analysis of wrinkling limit of rotary-draw bending process for thin-walled rectangular tube

The rotary-draw bending process for thin-walled rectangular tube of aluminum alloy may produce a wrinkling phenomenon if processing parameters are inappropriate, especially for tubes with thin wall and small bending radius. To predict this wrinkling rule rapidly and accurately, here, a wrinkling wave function was proposed and a wrinkling prediction model was developed based on the deformation theory of plasticity combined with the energy method, and then the minimum bending radius without the occurrence of wrinkling in the process was obtained. Furthermore, the effects of geometrical parameters and the material properties of the tube on the minimum bending radius were analyzed. The results show that larger thickness-to-width ratio (t/b) and thickness-to-height ratio (t/h) are beneficial to improve the wrinkling limit of the tube. The minimum bending radius becomes smaller with an increase in strain-hardening exponent of the tube, whereas with the strength coefficient decreasing. And the Young's modulus has little effect on the wrinkling limit. These achievements are helpful to develop the bending technique and provide a guideline in rotary-draw bending process for thin-walled rectangular aluminum alloy tube.     

电机壳铸件气冲气推造型参数的优化

气冲气推成型触头造型机是近几年出现的一种新型造型设备,砂型紧实度高而且均匀,有利于实现造型机械化生产.介绍了该造型试验机在电机壳铸件造型中的应用,并针对此造型机实砂过程及其效果的评价,设计了一种试验方法,实现造型参数的优化选择,以利干该造型机的进一步推广应用.     

可变纤维增强反应注射成型工艺及其混合头设计

为了克服反应注射成型和结构反应注射成型存在的诸多缺陷,提出采用可变纤维增强反应注射成型技术。详细介绍了该技术的原理、工艺过程及相关设备,并设计了新型混合装置。实践表明:这种先进成型工艺具有明显的优势,采用该新型混合装置实现了可变纤维(纤维长度、含量、种类和分布等可变)与A/B料的良好混合,制备了性能优良的汽车内饰制品。     

基于PS2F的铝型材拉弯回弹研究

采用型材2D拉弯仿真软件PS2F对矩形截面铝型材张臂式拉弯进行了分析,探讨了弯曲半径、弯曲角度及铝合金材料性能对型材单曲率拉弯回弹的影响。研究结果表明,在缺省的拉伸力控制参数设置及夹钳加载轨迹由软件自动优化的情况下,对于给定的弯曲半径,型材零件端部的回弹量随弯曲角度的增加呈指数上升趋势;对于一定的弯曲角度,零件端部回弹量随弯曲半径的增加而线性增加;在相同弯曲半径和弯曲角度的情况下,材料性能对拉弯回弹量有重要的影响。     

Determination of forming limit of a structural aluminum tube in rubber pad bending

Rubber pad bending is a novel technique for producing space frame to reduce the weight of automobiles because it can produce bent profiles with various curvatures in a single production set-up. As in other bending processes, cross-section of the aluminum tube deforms during the process. Such a deformed geometry diminishes bending rigidity, making it inappropriate for a structural use in some cases. Thus, it is important to determine a minimum radius of curvature with sufficient bending resistance. In this study, experimental set-up was developed to investigate deformation characteristics of an extruded rectangular aluminum tube in rubber pad bending. For better understanding of the effect of process parameters such as the material property of rubber and roller diameter, finite element (FE) analyses were also conducted. The ratio of the second moment of inertia of the initial and deformed cross-sections of the tube was introduced as a measure of cross-sectional deformation to represent the variation of bending rigidity of the bent tube. In result, a critical value of sectional deformation and minimum formable radius of curvature with maintaining suitable sectional bending rigidity were, respectively, determined under the present process conditions investigated.     

铝合金型材聚氨酯柔性垫弯曲研究

型材聚氨酯垫弯曲是一种将超弹性的聚氨酯垫作为弯曲凹模的型材弯曲新技术。通过调节型材压入聚氨酯垫的深度,可得到具有不同曲率半径甚至变曲率半径分布的零件。文章首先设计并制造了聚氨酯垫柔性弯曲装置。利用研制的聚氨酯垫柔性弯曲装置,以槽形截面铝合金型材为对象,通过实验,研究了压入深度和型材曲率半径的关系,以及型材截面形状对曲率半径的影响。结果表明,对于所研究型材,其曲率半径随压入深度的增加而减小。当压入深度较小时,曲率半径迅速减小;随着压入深度的继续增加,曲率半径的缓慢减小。当采用不同弯曲方式时,型材截面抗弯模量的变化以及截面中性层位置的变化,都对弯曲件的曲率半径有重要影响。截面抗弯模量越大弯曲越困难,截面中性层与压辊轴线的距离越大,曲率半径越小。