薄板台阶断面件FCF加工硬化特性

针对一种薄板台阶断面铝板材零件进行了FCF新工艺试验,采用DEFORM有限元软件对该零件冲压、冷锻组合加工变形过程进行了数值仿真,获得了其等效应力和应变分布,并通过显微硬度(HV)表征了试件表面的实际加工硬度特性。试验研究表明:成形过程中变形区及邻域材料的冷变形硬化效应比单一冲压和冷锻时更为显著,在该工艺中表现为冲裁与挤压、压印的迭加复合;零件下平面较上平面相应处的硬度值要高,差值范围在5%～10%之间;零件上下平面硬化效果从台阶内外缘处径向扩展逐步减弱,径向硬化效应区在0～1.4t(t为料厚)范围内。由此提出了一种新的加工硬化模型。     

基于牺牲活泼金属法的薄板工件小尺寸台阶孔电解加工研究

为在不锈钢304薄板工件上加工出高质量的小尺寸台阶孔,提出了一种电解加工薄板小尺寸结构的新方法——牺牲活泼金属法,改善了传统电解加工过腐蚀和杂散腐蚀缺陷。首先,基于电场理论建立了关于电位和电流密度的数学模型,并采用多物理场仿真软件COMSOL对传统电解法和牺牲活泼金属电解法分别进行了数值模拟,模拟结果表明:牺牲活泼金属法阳极工件表面电流密度的差异化分布将有助于小尺寸台阶孔的成型;然后,通过单因素试验研究,确定了适合用于小尺寸台阶孔电解加工的工艺参数;最后,当电压为10 V,占空比为50%,转速为3 000 r/min,电解液浓度为1 mol/L NaNO_3和0.1 mol/L C_6H_8O_7的混合溶液时,在不锈钢304薄板上成功获得了加工质量较好的小尺寸台阶孔,试验结果与数值模拟结果吻合。     

拼焊板方盒件拉延成形焊缝移动规律研究

将不同厚度、不同材质的平板材料焊接在一起形成的平板坯料称为拼焊板.拼焊板冲压成形技术在汽车工业和船舶工业具有广泛的应用前景。对相同材料不同厚度拼焊板方盒件进行了拉延实验研究和数值模拟,得到了盒底部焊缝向厚板侧移动、法兰区及侧壁处焊缝向薄板侧移动的焊缝移动规律,分析了压边力对焊缝移动距离的影响。     

大型圆柱锻件深冲孔最小孔径比的数值模拟研究

基于DEFORM-3D有限元软件,对高径比H/D=2.5时不同直径的大型圆柱锻件深冲孔工艺过程进行了模拟分析。研究了冲头直径变化时冲孔载荷的变化规律,并同冲头失稳时的临界载荷进行对比,找到了确保冲头稳定的最小孔径比dmin/D的取值。研究结果可以为大型圆柱锻件深冲孔工艺参数的制订提供理论依据。     

高直臂小间距等厚板材零件步进式冲锻工艺

针对高直臂小间距、不能展平的等厚板材零件,提出了步进式冲锻成形工艺。该工艺先通过冲压成形零件的大间距两直臂,然后通过若干次弯曲工步来缩小两直臂间距直至达到目标值。每次弯曲成形后对工件弯曲变形部位需进行冷锻平整,选择合理的工步数是保证冷锻过程中不出现材料重叠、起皱或破裂等现象的关键。建立了流线型弯曲的数学模型,通过该模型得到每个弯曲工步极限图。采用数值模拟结合试验的方法获得了无工艺缺陷的产品,产品性能优良,生产效率高。该步进式冲锻工艺为成形高直臂小间距等厚金属板材零件提供了新途径。     

基于正交试验的汽车覆盖件冲压工艺参数优化

将正交试验设计方法与冲压数值模拟相结合,综合评估了冲压过程中的压边力、摩擦系数、模具间隙和冲压速度等对汽车覆盖件冲压成形质量的影响,并确定优选的工艺参数组合.以汽车翼子板为例,建立了冲压件和模具的计算机辅助工程模型.运用正交试验方法进行仿真计算方案的设计,通过对仿真数据的方差等分析,找到了最优的工艺参数组合.所得结论对冲压工艺的设计具有指导意义.     

内台阶锥形环件轧制三维有限元模拟和工艺优化设计

以Abaqus三维有限元模拟软件为平台，对内台阶锥形环件的轧制过程进行了数值模拟，通过模拟计算揭示了内台阶锥形环件轧制缺陷的形成机理。根据轧制难度分析和有限元模拟结果，对轧制毛坯尺寸和轧制孔型进行了优化。采用铅环件试样在D51—160轧环机上进行了内台阶锥形环件的轧制试验，轧制了合格的内台阶锥形环件。模拟和试验结果表明，轧制毛坯尺寸和轧制孔型优化方案是合理的，基于变形模拟的轧环工艺优化方法是有效的。     

薄板冲头

在薄板上手工冲孔,一般用图1的冲头。但它有三个缺点:1.中心不易找正;2.元度不正;3.只能冲直径10毫米以下的孔。图2所示的冲头,结构简单、制造方便、操作容易、效果好。它能冲直径25毫米以下的孔,最厚能冲1.5～2毫米厚的薄板。操作时,在薄板上需要冲孔的地方,先用     

拼裁焊缝在拉伸成形中的流动研究

对0.8mm与1.5mm两种厚度的母材使用CO2激光器进行了激光拼焊试验。运用AutoForm数值仿真软件建立了差厚激光拼焊盒形件有限元模型,通过有限元数值仿真模拟研究了差厚激光拼焊盒形件在冲压成形后的焊缝流动现象,并与实冲试验结果进行了比较。结果表明：有限元数值仿真模拟能够较为近似地反映差厚激光拼焊盒形件在冲压过程中的焊缝流动现象,数值模拟和试验研究均表明,差厚激光拼焊盒形件在冲压过程中会发生薄侧材料向厚侧材料的流动,从而给激光拼焊板冲压质量带来一定的影响。     

薄板的剪切压焊

剪切,是使材料分离的加工方法。日本东京大学生产技术研究所最近研究成功了一种利用剪切实现两块薄板接合在一起的剪切压焊法。把两块薄板叠在一起,进行冲剪。当冲头与模子的间隙较小时,使材料产生局部变形,并沿剪切线产生很高的热量;另外,冲剪时,冲头与材料之间产生压力,不断地把材料从冲剪一侧向挤压的一侧产生压力。冲头反复上     

Simulation and Experiment on Workability for Cold Pressure Forming of Sheet Metal Part with Step Cross-section

In modem manufacturing, a new type of sheet metal part with step cross-section in both inner hole and outer edge is proposed. The traditional stamping separating processes can only produce sheet metal part with vertical cross-section. According to the latest developing theory and potential of cold pressure forming: combination of pressure and cold forging, a new flow control forming of sheet metal(FCF) is excogitated based on blanking process of general stamping and combined with cold forging processes such as extrusion and coining, etc, which is aiming at the above-mentioned new type of sheet metal part. With utilization of this new process, the new type of sheet metal parts can be manufactured. In order to shorten the testing period, the numerical simulation was carried out by using DEFORM-3D software, and both deformation and mechanics rules were analyzed. Based on the simulation, both punching part and blanked parts of this new type were successfully developed. Then a new conception of optimal distance between the step walls of inner hole and outside edge was proposed and the design principle for its numerical value was inferred. Furthermore, a mold set for combination of stamping & cold forging was designed and manufactured, by which the technologic experiments were taken for validation with Aluminum plate of thickness 2.35 mm for power battery cover board, which verified the principle of the distance between the step walls. The research of cold pressure forming of thin sheet metal with step cross-section is significant, not only to the development of modem mechanical manufacture, but also to metal plastic forming science.     

Finite-element simulation of hole-flanging process of circular sheets of anisotropic materials

A hole-flanging operation on a flat circular sheet with a hole in the center is simulated by an incremental elasto-plastic finite-element method, which incorporates strain-hardening and anisotropy in the direction normal to the sheet, with care taken to describe the boundary conditions of penetration, separation and the alternation of the sliding—sticking state of friction. The simulation clearly demonstrates the processes of generation of deformation shape until unloading. The calculated sheet geometries and the relationship of punch load to punch stroke are in good agreement with the experimental data.The stress at the hole periphery in the flange is assumed to a state of circumferential uniaxial tension, in order to simplify the fracture mode as a simple tension test. By making use of the instability of uniaxial tension, an approximate relationship to determine the onset of necking of the hole periphery in the hole-flanging process is derived and it is found to be influenced by the process geometry and the plastic properties of the material, such as the stress-concentration factor K, strain-hardening n and normal anisotropy R, and the estimated value, being obtained by the derived equation, agrees well with the experimental data.It is noted that the derived relationship for estimating the instability of the hole-flanging process can be combined into the developed finite-element model to simulate the critical condition of the limiting deformation of the hole-flanging process. This combined method could possibly be applied towards improving both the manufacturing process and the design of tools for the hole-flanging operation.     

扭臂模锻成形过程的三维有限元模拟

针对扭臂模锻成形过程,采用三维刚塑性有限元法进行了数值模拟,分析了金属的塑性变形行为,对可能产生的缺陷进行预测,给出了等效应力、等效应变的分布情况,从而为工艺制订和模具设计提供理论依据。     

An approach to eliminate stepped features in multistage incremental sheet forming process: Experimental and FEA analysis

Incremental sheet forming (ISF) is a recently developed manufacturing technique. In ISF, forming is done by applying deformation force through the motion of Numerically controlled (NC) single point forming tool on the clamped sheet metal blank. Single Point Incremental sheet forming (SPISF) is also known as a die-less forming process because no die is required to fabricate any component by using this process. Now a day it is widely accepted for rapid manufacturing of sheet metal components. The formability of SPISF process improves by adding some intermediate stages into it, which is known as Multi-stage SPISF (MSPISF) process. However during forming in MSPISF process because of intermediate stages stepped features are generated. This paper investigates the generation of stepped features with simulation and experimental results. An effective MSPISF strategy is proposed to remove or eliminate this generated undesirable stepped features.     

Numerical simulations on reducing the unloading springback with multi-step multi-point forming technology

Multi-point forming (MPF) is an innovative flexible manufacturing technology for three-dimensional sheet metal forming. It replaces the conventional solid dies with a set of height-adjustable discrete punches, called the “punch group”. A set of punches can construct various three-dimensional curved surfaces freely and conveniently, through adjusting the relative position of each punch. MPF technology not only saves a significant amount of money and time in the design, manufacture, and adjusting of the dies but it can also be applied to change the deformation path and to improve the forming quality. Unloading springback is an inevitable phenomenon in sheet metal forming using MPF. To control and reduce springback, numerical simulations for the MPF process and the unloading springback are carried out using the explicit-implicit coupled finite element method. Subsequently, influencing factors such as thickness, deformation amount, and material properties of MPF springback are researched to investigate the MPF springback tendency. Next, the multi-step MPF technology is introduced to reduce MPF springback. Based on numerical simulation analysis, it is obviously validated that the unloading springback is decreased when the multi-step MPF method is applied. Finally, it is verified that the equidifferent deformation path and small deformation amount of each forming step can improve the workpiece stress state and minimize the unloading springback effectively by an evaluation result of the deformation path effect on the multi-step MPF.     

轴承套圈锻造数值模拟

运用MSc—Marc软件对轴承套圈锻造加工进行了数值模拟分析，以金属成形理论和有限元方法基本原理为基础，建立了热力偶合刚粘塑性锻造模型。以第二代轮毂轴承外圈锻造为例进行模拟分析，对预成形模型的实验和模拟结果作了对比，提出产生过大锻造力的一个原因是最终成形阶段工件在模腔内分布不均使变形速率急剧增加，提出了预成形坯的设计优化准则，依此设计的第二代轮毂轴承外圈的优化预成形结构、锻造力比传统设计下降了一半以上。     

星形套闭塞模锻光塑性模拟研究

利用光塑性方法以聚碳酸脂为模拟材料研究轿车等速万向节星形套闭塞模锻成形过程，获得星形套闭塞模锻成形过程的三维光塑性应变分布，提出其应变分布特征，并对典型截面应变进行计算分析，研究结果可实际钢质星形套闭塞模锻工艺和模具设计起一定的指导作用。     

The design of a semi-additive manufacturing shape using metal 3D printing for a partially strengthened mold based on a high-alloy tool steel powder

In this paper, describe the fabrication of high strength punch molds that can be applied to ultra-high strength sheet materials after processing. A method for improving the strength of the punching die by additive manufacturing (AM) of a high strength powder material using a metal 3D printer was proposed. Furthermore, a semi-additive technique was proposed to increase the punch strength through partial AM of specific parts of the punch that require high strength. A preprocessing process for predicting the semi-additive shape for the punch function portion is proposed for application of the AM technology of a metal 3D printer to this semi-additive technique. The preprocessing for determining the semi-additive shape consists of the predicting step of the punch strength based on the shear process of the sheet material, analyzing step the stress distribution of the punch, defining step the semi-additive range, designing step the semi-additive shape, and verifying step the additive interface strength. Based on this simulation, the range of shapes for the semi-additive was 1.21 mm and 2.62 mm for sheet material CP1180 and 1.3 mm and 3.2 mm for sheet material 22MnB5. The shape and range determined in the simulation process defines a semi-additive area (volume) for the 3D printing AM technique using a high-strength powder material, and a semi-additive punch was manufactured according to the defined area. The semi-additive punch (HWS powder material) fabricated in this study was performed a durability test for validity verification in the piercing process of high-strength sheet material (CR980). This validation test compared the state of the punch after 1000 piercing processes with a typical cold piercing punch (SKD11 solid material). From this test, the feasibility of the semi-additive punch was confirmed by showing a similar state of scratches and abrasion from the two punches. The simulation analysis processor for the additive shape and the additive range prediction for the semi-additive punch manufacturing presented in this paper can be useful for the additive manufacture of cutting and trimming punch mold.

     

金属板料成型的三维弹塑性大变形有限元模拟

根据非线性连续介质力学的基本原理推导板料成型分析的三维弹塑性大变形全量拉格朗日法的有限元列式，首次给出其矩阵表达式的显式，并对圆板半球形凸膜胀形进行了模拟，模拟与实际结果吻合较好。     

FEA-aided design of multi-stage drawing process and tooling for production of a miniature sheet metal component

This paper presents the design of multi-stage drawing process and tooling aided by finite element analysis (FEA) for fabrication of a miniature sheet metal component, made of a cold-reduced carbon steel material (SPCC). To design such a tooling, it is essential to figure out how many intermediate drawing steps are needed to produce the final part without deformation defect. First of all, a four-stage drawing process and a set of four-station tooling are designed. This pre-designed process is then analyzed by simulation, and the deformation behavior and formability in each stage is revealed. Based on the revealed deformation behavior and formability, the design of the process and tooling is confirmed. The reasonable drawing ratio and drawing depth in each drawing operation are determined. The size, clearance, and the corner radii of punch and die in each stage are also identified. The designed process and tooling are finally implemented. Through experiment, the “right design in the first time” is realized, and the simulation and experiment are found to have a good agreement. The research further demonstrates that the FEA simulation can be used as an effective tool to aid the design of metal-formed component, tooling, and process in upfront design process.