四边圆角形截面筒形件的旋压成形方法研究

基于导杆机构运动原理,提出了一种四边圆角形截面筒形件的旋压成形方法,运用高副低代的转化方法,建立了四边圆角形截面筒形件旋压成形过程中旋轮运动轨迹的数学模型,得到了旋轮及零件的机构运动关系;同时,对成形过程中旋轮运动轨迹进行仿真与计算,分析了旋轮个数与轮盘尺寸对旋压成形过程的影响;得出成形过程中有利于零件成形质量及改善轮盘速度波动情况的轮盘尺寸与旋轮数量,为四边圆角形截面筒形件的加工工艺研究提供了理论基础.     

铝合金筒形件强力正旋的应力应变分析

为确定更为符合实际的铝合金筒形件三旋轮正旋工艺参数选用原则,以某厂某型号铝合金筒形旋压件为研究对象,利用大型非线性有限元软件ANSYS对其在不同工艺参数下的三旋轮正旋旋压过程进行了三维动态模拟和应力应变分析。分析结果表明:当旋轮进给量在0.66～1.58 mm/r时,其应力和应变变化不大,相对比较稳定;旋轮圆角半径大于0.6倍且小于1.25倍铝合金筒形件坯料厚度比较合适;旋轮成形角取22°～24°较佳;旋轮直径取220～240 mm较合适。研究结论对铝合金筒形件正旋的进一步研究和生产实际具有重要意义。     

浅析多楔带轮旋压成形工艺优化

多楔带轮在旋压成型工艺过程中，旋轮容易出现黏结、磨损、轮齿断裂、齿根和齿面开裂、R圆角塌陷等缺陷。上述缺陷的形成很大程度上是因为旋轮在成形过程中承受了较大的成形载荷，从而导致旋轮发生严重的磨损甚至破裂，不仅影响零件的成形质量，也降低了模具的使用寿命。尤其是齿形旋轮受损更严重。因此，有必要对多楔带轮旋压工艺中的齿形成形进行工艺优化，以达到降低齿形旋轮所受载荷、提高旋轮使用寿命的目的。本文采用正交试验方法，然后结合有限元软件对各组试验进行模拟，从而获得一组最优方案：主轴转速为500r/min，旋轮进给速度为0.5mm/s，旋轮直径为220mm，并用物理试验验证了最优方案的合理性与再现性。并将该最优方案在旋压机上进行试验验证，旋制出了满足产品质量要求的多楔带轮。     

多V型皮带轮旋压成形过程的有限元分析

基于动力显式有限元软件,以电磁离合器皮带轮为侧,开展了两个工序的旋压成形工艺的数值模拟,研究了旋压成形过程中材料变形情况,对成形件的应力应变分布进行了分析。模拟结果表明：采用旋压成形工艺,通过设置合理的进给量、芯模转速等参数,成形出的零件不仅形状和尺寸满足要求,而且芯模和旋轮所受载荷不大,旋轮最大载荷为540kN,芯模最大载荷为19kN。该研究对旋压带轮的非线性有限元分析和实际生产中设备的选择具有一定的参考和实用价值。     

异型薄壁壳体强力旋压三维有限元模型的建立

基于ABAQUS/Explicit平台,在解决建模过程中有关旋轮定位、旋轮运动轨迹确定、连续变壁厚坯料壁厚定义的实现等关键问题的基础上,建立了异型薄壁壳体强力旋压三维弹塑性动态显式有限元模型。基于该模型研究发现:在成形过程中后期,旋轮前方易于出现金属堆积,从而使后方材料拉薄,尤其是靠近工件口部的部位壁厚剧烈减薄。提出了通过控制坯料局部厚度和旋轮与芯模间间隙的方法来改善成形过程中金属堆积和壁厚过度减薄现象。     

HGPX-WSY型液压仿形旋压成形机床的研制

介绍了HGPX—WSY型自动液压仿形缩脚机床的设计方案、技术特色、总体结构、液压、电器控制系统及应用实例。该机床采用PLC控制、全液压驱动，旋轮的运动轨迹由仿形模板决定，具有旋压成形及整形或切边多重功能，特别适用于各类筒形及杯形类零件的局部缩径成形。     

回归分析普通旋压筒形件的成形性

筒形件普通旋压中,制品常出现板材拉薄开裂和板材失稳起皱等成形性重缺陷。通过对铝合金材料筒形件普通旋压试验,发现板厚比t_0/d、旋压比D_0/d、旋轮移动速度V、旋压初角θ_0、旋轮移动距离p等多种加工参数对产品成形性影响很大。因此对生产实践和试验中获得的原始数据进行了计算机多重回归分析,得到了确保产品成形性的最适工艺参数。     

三边圆弧形截面薄壁零件的旋压成形方法研究

基于摆动导杆运动原理提出了一种非圆截面薄壁零件的旋压成形（简称“非圆旋压”）方法。基于此原理,运用高副低代的方法建立了三边圆弧形截面薄壁零件旋压成形过程中旋轮运动轨迹的精确数学模型,研究了三边圆弧形截面薄壁零件旋压过程中旋轮及零件的运动关系;同时对成形过程中旋轮运动轨迹进行仿真计算,分析了轮盘尺寸与旋轮个数对旋压成形过程的影响,并得出有利于零件成形的轮盘尺寸与旋轮个数。为后续相关截面的工艺研究与应用及机床研发提供理论基础。     

多道次普旋技术发展与旋轮轨迹的研究

旋轮运动轨迹是多道次普旋中的关键问题 ,对旋压成形的成败具有重要影响。本文简述了旋轮运动轨迹的实现方法及常见形式 ,对目前旋轮轨迹以实验方法为主的研究现状进行了综述 ,提出运用有限元数值模拟技术 ,以理论分析为基础确定旋轮轨迹形式是今后研究的发展方向     

筒形件强力反旋的数值模拟及旋压力分析

以大型非线性有限元软件ANSYS/LS-DYNA为分析平台,通过对18种几何尺寸和参数不同的筒形件三旋轮强力反旋旋压过程的三维动态模拟,得到了它们的旋压力以及旋压力随不同减薄率,旋轮进给量,旋轮圆角半径,旋轮成形角,旋轮直径和毛坯内径的变化曲线.分析结果表明:随着减薄率、旋轮进给量、旋轮圆角半径的增加,旋压力各分力基本呈上升趋势.随着旋轮成形角、旋轮直径和毛坯内径的增加,旋压力各分力均呈非线性变化,但变化均不大.总之,减薄率、旋轮进给量、旋轮圆角半径对旋压力的影响较明显,而旋轮成形角、旋轮直径和毛坯内径对旋压力的影响较小.另外,随着上述各影响因素的变化,旋压力的轴向分力、切向分力与径向分力的比值基本保持不变.     

AZ31镁合金手机外壳冲压模具的设计与成形工艺

设计了手机外壳冲压模具,研究了镁合金薄板温度、模具温度、拉深速度以及润滑条件对AZ31镁合金手机外壳成形质量的影响。结果表明:镁合金薄板在加热到350～400℃,且凹模的温度不低于薄板温度,较低的凸模温度(50～90℃),较低拉深速度(6mm·s-1)及仅对薄板与凹模和压边圈接触部位润滑的条件下,可以制备出尺寸精度较高的镁合金手机外壳。     

Analysis of the bulging process of an AZ31B magnesium alloy sheet with a uniform pressure coil

As the lightest metal material, magnesium alloy is widely used in the aerospace, automobile, and consumer electronic industries. However, magnesium alloy sheet has poor formability at room temperature. Electromagnetic forming is a high velocity forming technique that can promote the formability of low ductility materials, improve the strain distribution of workpieces, and reduce their wrinkling and springback. In this work, a uniform pressure coil was used to bulge AZ31B magnesium alloy sheets. The finite element method was then used to analyze this bulging process. The bulging contours and displacements of AZ31B magnesium alloy sheets were consistent with the experiment results. The distribution of the magnetic field intensity and magnetic field forces were found to be better than using a flat spiral coil. The deformation rule of AZ31B magnesium alloy sheet using the uniform pressure coil differed from that using the flat spiral coil. The largest strain occurred at the center of the sheet.     

Effects of temperature and driver sheet for magnesium alloy sheet in magnetic pulse forming

Thermal effect from warm temperature is always used to improve the formability of AZ31 magnesium alloy sheet. However, it is seldom employed to deform AZ31 sheet in magnetic pulse forming process, due to increasing resistivity and decreasing effect of high strain rate. In this study, Al driver sheets without heating were used to strength effect of high strain rate and drive AZ31 sheet with warm temperature to deform. Method of numerical simulation was used to analyze magnetic pulse forming of AZ31 sheet with driver sheet and temperature. Magnetic flux density and magnetic force with and without Al driver sheet (thickness of 1, 1.5, and 2 mm) and different temperature (25, 100, 150, 200, and 250°C) were investigated. Deformation processes and velocity with Al driver sheet and different temperature were analyzed. The results indicate that it is better for formability of AZ31 sheet to adopt 1-mm Al driver sheet at higher discharge energy and warm temperature.     

Effects of driver sheet on magnetic pulse forming of AZ31 magnesium alloy sheets

In this work, the formability of AZ31 magnesium alloy sheets was investigated by electromagnetic bulging experiments with driver sheet. Al (0.5 mm, 1 mm, and 2 mm thick) and Cu (1 mm thick) driver sheets were used to accelerate the AZ31 sheet in electromagnetic forming (viz magnetic pulse forming) process. In order to evaluate the effect of impact induced by driver sheet, the electromagnetic bulging experiments with gap between AZ31 sheet and driver sheet were investigated. Compared with quasi-static forming limit results, increases in the major and minor principal strains (with 0.5 mm, 1 mm driver sheet, and without driver sheet) of approximately 68 % and 72 % were achieved, respectively. However, the major and minor principal strains with 2 mm Al driver sheet increased about 148 % and 184 %. When the energy is up to 2.788 kJ after the first crack (with 1 mm Al driver sheet) producing, the major and minor strains increase about four times compared to the quasi-static condition.     

Effects of process parameters on electromagnetic forming of AZ31 magnesium alloy sheets at room temperature

In this work, the effects of process parameters on AZ31 magnesium alloy sheets were investigated by electromagnetic bulging experiments. The bulging height increases with increasing discharging energy, which is adjusted by tuning discharge voltage and capacitance. The limit dome height of electromagnetic forming is markedly improved as compared to quasi-static forming. In order to improve the efficiency of the energy, 0.5- and 1-mm thick Al driver sheet were used to accelerate the magnesium alloy sheets. For rupturing the AZ31 sheet, the discharging energy can be reduced from a maximum value of 4.356 kJ (no driver) to 2.304 kJ (with1-mm Al driver sheet). The numerical simulation for the electromagnetic forming of AZ31 sheet is performed by means of ANSYS FEA software. The change of velocity, strain rate, and plastic strain energy were analyzed by simulation. Compared with quasi-static forming limit results, increases in the major and minor principal strains of approximately 68 and 72 % were achieved, respectively.     

AZ31B镁合金搅拌摩擦焊焊接工艺研究

采用搅拌摩擦焊对AZ31B镁合金板材进行了焊接试验,研究了搅拌头旋转速度、焊接速度和搅拌头轴肩下压量对焊接接头成形质量的影响。结果表明,搅拌头转速过快或焊接速度过慢时,焊缝会出现局部过热甚至熔化现象;反之,当搅拌头转速不够或焊接速度过快时,材料不能充分流动,会形成隧道型缺陷或表面沟槽。当搅拌头轴肩下压量过小时,焊缝内部组织疏松或出现孔洞、隧道型缺陷,焊缝表面出现沟槽,甚至使焊缝金属液外溢;搅拌头轴肩下压量过大,会造成摩擦力及搅拌头前移阻力增大、焊缝凹陷及出现飞边。当搅拌头转速为1200～1500r／min、焊速为30～60mm／min,搅拌头轴肩下压量为1．5～2．0mm时,可得表面成形良好、内部无孔洞和隧道的焊缝。     

AZ31镁合金板材在热处理中组织和性能的演变

研究了热处理对AZ31镁合金轧制板材显微组织、室温力学性能和成形性能的影响。热处理温度在300～350℃范围时,显微组织观察表明,热处理后孪晶消失、组织逐渐趋于均匀化、平均晶粒尺寸变小;力学性能和胀形性能测试结果表明,板材的屈服强度明显降低、抗拉强度略有下降、屈强比降低、伸长率提高,杯突值提高。在350℃、15 min空冷处理后,AZ31镁合金板材的综合性能最好。     

镁合金板材温热成形韧性破裂准则

针对镁合金板材温热成形数值模拟过程中无法精确判断材料损伤破裂失稳的技术难题,建立考虑温度效应的镁合金板材温热成形韧性破裂准则;基于单向拉伸试验和温热成形极限试验,采用试验和数值模拟相结合的研究方法,确定镁合金板材温热成形韧性破裂准则中的材料参数;以建立的考虑温度效应的镁合金板材韧性破裂准则作为判断破裂的标准,对AZ31镁合金板材的温热成形极限进行预测,并且通过温热拉延试验进行试验验证。研究结果表明,考虑温度效应的镁合金板材韧性破裂准则适合镁合金温热成形数值模拟,应用建立的韧性破裂准则成功的预测板材温热破裂方式,揭示板材温热成形韧性破裂机理,预测结果与试验结果体现较好的一致性。     

Effect of heat treatment and number of passes on the microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy

In this paper, the effect of heat treatment and number of passes on microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy samples were investigated. From six samples of as-cast AZ91C magnesium alloy, three plates were pre-heated at temperature of 375°C for 3 hours, and then were treated at temperature of 415°C for 18 hours and finally were cooled down in air. Three plates were relinquished without heat treatment. 8 mm thick as-cast AZ91C magnesium alloy plates were friction stir processed at constant traverse speed of 40 mm/min and tool rotation speed of 1250 rpm. After process, microstructural characterization of samples was analyzed using optical microscopy and tensile and Vickers hardness tests were performed. It was found that heat treated samples had finer grains, higher hardness, improved tensile strength and elongation relative to non-heat treated ones. As the number of passes increased, higher UTS and TE were achieved due to finer grains and more dissolution of β phase (Mg₁₇Al₁₂). The micro-hardness characteristics and tensile improvement of the friction stir processed samples depend significantly on grain size, removal of voids and porosities and dissolution of β phase in the stir zone.

     

AZ31镁合金盒形件变压边力温热拉延工艺

通过温热交叉轧制工艺制备了板形以及成形性能良好的AZ31镁合金薄板;开发了可加热的变压边力双动液压机,并详述其工作原理;采用不同的压边力方案,对盒形件进行温热拉延实验,分析了变压边力对AZ31镁合金板材温热拉延性能的影响。结果表明:最佳的压边力变化方案是压边力随凸模行程先增后减的模式;采用变压边力技术可以将AZ31镁合金盒形件的拉深深度提高13·2%。