镁合金AZ31B直齿锥齿轮热锻成形研究

根据镁合金AZ31B的高温流动应力曲线,建立了包含应变的三维加工图,反映了温度、应变和应变速率对功率耗散系数和流变失稳区的影响,确定了合适的热变形范围,即温度为250-325℃、应变速率为0．1～1s^-1。在此基础上,研究了镁合金直齿锥齿轮的锻造成形,制定了无齿形预锻和终锻两步等温锻造工艺,在MSC．Marc平台上进行了锻造过程的模拟,基于模拟结果,完成了镁合金直齿锥齿轮的锻造成形实验。     

Effects of forging parameters on uniformity in deformation and microstructure of AZ31B straight spur gear

The effects of forging parameters on the deformation and microstructure distributions of as-forged straight spur gears were investigated by finite element (FE) simulation and statistical analysis method. Spur gear forging using the movable cavity die design was investigated by integrating the FE method with the microstructure evolution models for AZ31B magnesium alloys. The required inputs such as flow stress curves and microstructure evolution models, were obtained through the Gleeble thermal mechanical testing and quantitative metallography analysis method. Numerical simulation and experimental examination confirm that both the deformation and microstructure are non-uniformly distributed in the as-forged gears. Decreasing deformation temperature or increasing strain rate is beneficial to obtaining fine-grained microstructure but is harmful to the uniformity in deformation or microstructure. The level of the non-uniformity results from the complex shape of gear and the friction between the billet and dies, which is closely associated with the characteristics of flow stress curve.     

镁合金有限元与三维加工图相结合的材料驱动的可加工性模拟

基于PRASAD提出的传统的二维加工图理论,建立考虑应变的三维加工图,描述功率耗散系数和流变失稳区域随应变速率、温度和应变的变化。三维加工图说明了材料的内禀可加工性,而有限元分析方法可得到材料在特定工艺条件下应力、应变、应变速率及金属流动情况,说明了由模具形状和工艺条件决定的应力状态可加工性。基于此,提出一个新的由材料驱动的热变形可加工分析方法,联合考虑有限元和三维加工图,可以说明整个热加工过程的材料可加工性（包括应力状态可加工性和内禀的可加工性）。通过此方法,研究难变形金属镁合金的热锻过程,包括复杂热锻直齿锥齿轮的三维热力耦合有限元和三维加工图的集成模式。基于得到的研究结果,成功进行了热锻试验。试验表明新的方法用于确定最佳工艺参数是合理的。     

Controlling Flow Instability in Straight Spur Gear Forging Using Numerical Simulation and Response Surface Method

Workability domain without the onset of flow instability was developed by numerical simulation and response surface method(RSM) for complex-shaped straight spur gear forging. The processing map of AZ31 B alloys was calculated from flow stress curves and then integrated with the finite element model to simulate the distribution of flow instability in the straight spur gear undergoing isothermal forging process. Occurrence of flow instability depends on forging temperature, punch velocity and billet reduction. Taking forging temperature and punch velocity as design variables, while billet reduction as response variable, RSM of workability domain was established. Analysis of variance indicates that forging temperature is the most significant factor determining the appearance of flow instability in the forged gear. Flow instability is easier to take place at lower temperatures of 250 and 300 °C in the early stage of forging but at higher temperatures of 350 and 400 °C in the later stage of forging, which is attributed to different deformation mechanisms and dynamic recrystallization behaviors at different temperatures or deformation levels. Meanwhile, increasing punch velocity further reduces the workability of the forged gear.Four different processing paths were chosen to carry out the gear forging trials. Visual observations and metallographic examinations demonstrate that the developed workability domain contributes to optimization of forging parameters.     

镁合金体积成形进展

简要介绍了国内外学者、科技人员进行的ZK30,ZK60,AZ31,AZ31B,AZ61,AZ80,MB15等镁合金材料锻造、挤压方面的基础研究进展和一些简单的产品开发,阐明了镁合金从基本研究到镁合金产品产业化和商业化的发展方向。     

螺旋锥齿轮摆辗工艺研究

螺旋锥齿轮形状复杂,齿线长而弯曲,不易通过常规方法加工.摆辗作为一种新的塑性成形螺旋锥齿轮的方法,克服了精密模锻成形力过大的困难.基于有限元的方法,本文对螺旋锥齿轮摆辗成形过程进行研究,分析了成形各阶段的变形与载荷特性;针对摆辗最后阶段飞边面积较大、载荷过大的特点,提出了摆辗摆头改进的方法,减少了飞边面积,从而使得成形力减少了1/3;通过铅试件成形验证了摆辗螺旋锥齿轮成形过程,说明了摆辗螺旋锥齿轮是可行的.     

从动螺旋伞齿轮摆动辗压三维有限元模拟

从动螺旋伞齿轮的形状复杂,摆动辗压难度大。采用刚粘塑性有限元对从动螺旋伞齿轮摆动辗压工艺进行了模拟,获得了从动螺旋伞齿轮的摆动辗压变形规律和力能曲线。通过对辗压力模拟计算与实验结果的比较,阐释了有限元模拟计算辗压力的有效性和不足。最后指出了对螺旋伞齿轮进行高精度的计算模拟要考虑的问题。     

Precision forging technologies for magnesium alloy bracket and wheel

Fundamental investigations on precision forging technology of magnesium alloys were studied.As-cast billet prestraining and a new concept of hollow billet were proposed in order to reduce the maximum forming load.A schcme of isothermal forming and the use of combined female dies were adopted,which can improve the die filling capacity and ensure the manufacture of high quality forgings.By means of the developed technique,AZ80 alloy wheel and AZ31 alloy bracket were produced successfully at suitable proces...     

多向锻造对变形镁合金AZ31组织和力学性能的影响

文章采用不同锻造工艺对电磁连铸变形镁合金AZ31铸锭进行了多向锻造研究。结果表明,通过大变形的多向锻造后,变形镁合金AZ31可以得到有效细化,多向锻造有利于变形镁合金发生再结晶,锻造后变形镁合金AZ31最终得到均匀细小的等轴晶组织。工艺3得到最好的综合性能,锻造后变形镁合金AZ31硬度和抗拉强度分别提高了22.5%和33.5%,延伸率也有所提高。多向锻造后,室温拉伸试样的断口形貌出现大量的韧窝,表现为剪切断裂为主的韧性断裂。     

镁合金手机外壳冲模设计及实验研究

以AZ31B镁合金手机外壳冲模设计和在普通机械式锻压机上的冲压生产为例,对AZ31B镁合金冲压成形过程中的板料制备、冲模设计、模具及板料的温度、冲压变形速度、润滑剂的选用等关键技术作了较为系统的实验研究。实验表明,通过合理地选取模具参数并对拉伸速度、坯料及模具温度等主要影响因素的控制,可有效地解决AZ31B镁合金拉伸生产过程中的拉裂缺陷,在普通机械式锻压机上能成功地冲压出镁合金手机外壳。     

螺旋伞齿轮从动轮毛坯锻造成形数值模拟

“热锻造+机加工”是螺旋伞齿轮制造的一种有效方式,热锻件质量的好坏决定了最终产品的性能.通过运用有限元分析软件Deform-3D对螺旋伞齿轮从动轮毛坯的热锻造过程进行数值模拟,研究了锻造过程中金属流动规律.结果显示,金属在阶梯处流动困难,导致锻件阶梯处的应力应变大,温度高.通过对模具参数进行改进,可以改善金属的流动情况...     

AZ31镁合金无缝管材冷轧成形过程研究

镁合金在室温下塑性较差,导致其在轧制过程中组织分布不均而引起应力差异,因此从镁合金材料特性角度出发,分析成形过程中力学特征及组织演变过程就显得至关重要。基于此,本研究通过实验建立AZ31镁合金分段本构模型,构建包含晶粒拓扑技术的元胞自动机模型。借助二次开发技术,将上述本构模型、元胞自动机与有限元软件结合起来进行仿真,获得包含应力、应变、晶粒大小和分布规律等预测结果,对控制皮尔格轧制AZ31镁合金成形工艺以实现对成形和性能的协调控制具有一定意义,并通过实验对模拟结果进行验证。     

Forming of bioabsorbable clips using magnesium alloy strips with enhanced characteristics

The paper shows the feasibility of manufacturing surgical clips using bioabsorbable AZ31B magnesium alloy strips characterized by enhanced forming characteristics, and, at the same time, improved corrosion resistance to human fluids that make them suitable for temporary applications. The novel process chain used for the clip manufacturing includes an extrusion-cutting step, to fabricate strips with a peculiar shear texture and extremely refined microstructure, and a dedicated bending operation to achieve the clip final shape. The strip forming operation setup was numerically designed by a multi-level finite element approach to provide the clip required shape without fracture occurrence.     

镁合金网格壁板压弯成形数值模拟及实验研究

为探索镁合金整体壁板压弯成形的可行性,以及镁合金壁板压弯成形过程中金属的流动规律,对AZ31镁合金网格壁板压弯成形进行了数值模拟和实验研究。建立了有限元数值模拟的几何模型,采用有限元计算软件对AZ31镁合金网格壁板压弯成形过程进行了数值模拟研究,分析了镁合金网格壁板压弯成形中的温度场、应变场、应力场、破坏系数等的分布规律。确定了合适的AZ31镁合金壁板压弯成形工艺参数,并对镁合金网格壁板压弯成形进行了实验研究,获得了合格的镁合金网格壁板弯曲件,并分析了镁合金网格壁板成形件尺寸精度,模拟结果与实验结果相吻合,最大相对误差为16.7%。     

基于接触摩擦量化作用的镁合金轧制力预报研究

本研究针对镁合金热轧制工艺,通过协调有限元分析结果及物理试验数据,提出一种关于热轧制接触摩擦因子的确定方法,耦合多轧制工艺参数进一步拟合出其求解关系式,工艺参数包括：轧制温度,轧制速度以及压下率。在之前对AZ31B镁合金板材轧制过程轧制力预报模型及温度场数学模型建立研究的基础上,综合考虑接触单位压力及摩擦应力两方面因素的作用,对前期轧制力预报模型进行了优化重构,经确定接触摩擦作用到轧辊的压力约占整体轧制力的4.36%。     

直齿锥齿轮预锻齿形优化设计

基于典型差速器行星齿轮的热-冷复合成形工艺,分析了预锻齿形设计的重要性。应用Deform-3D软件模拟不同齿形方案的预锻变形过程,通过数值模拟结果对比分析与物理试验验证,总结出标准预锻齿形与非标准预锻齿形设计的优缺点。若预锻齿形采用标准齿形,精整量较大时在齿根处产生金属折叠,精整量较小时齿面精度低;若预锻齿形采用非标准齿形,即增大齿面冷精整量,减少齿根处冷精整量,热锻件经冷精整后可以达到零件要求,由此确定了非标准预锻齿形为较合理方案。     

Ductility of a magnesium alloy in warm forging with controlled forming speed using a CNC servo press

The influence of press ram motion on forging performance for magnesium alloys was examined at elevated temperatures using an upsettability test on a CNC servo press. The forging limit of a wrought AZ31B (Mg–3 mass%Al–1 mass%Zn) magnesium specimen, forged using applied deceleration of the press ram motion, was found to be 30% higher than the forging limit achieved without press ram motion control. A finite element analysis was conducted to model the experimental results. The calculated temperature distribution was relatively uniform during upsetting with decelerated ram motion, and the maximum equivalent strain was maintained at a low level. Experimental and simulation results suggested that the influence of the press ram motion on the ductility of the Mg specimen could be described by a strain localization model. Furthermore, the ductility of Mg specimens during decelerated ram motion was improved in backward extrusion.     

Analysis on flow stress of magnesium alloys during high temperature deformation

The flow stress of magnesium alloys during hot compression at different temperatures and strain rates was studied by experiments.Materials used were AZ91D alloys in as-cast,homogeneous treatment states,AZ31 and ZK60 alloys in as-cast state. The results show that the thermal simulation curves of different alloys differ from one another at the same deforming condition.The general curves of AZ31 and AZ91D alloys have the character of dynamic recrystallization.There are increase of true stress,drastic fallin...     

AZ系列镁合金热模拟挤压过程中挤压力的研究

通过在Gleeble1500D热模拟试验机上对AZ10、AZ31、AZ61和AZ91镁合金进行模拟挤压,并对热模拟挤压成形过程中的挤压力进行测定,研究AZ系列镁合金热模拟挤压成形过程挤压力及其组织变化。研究结果表明,在AZ系列镁合金中,随着合金元素含量的增多,挤压力逐渐增大,并且同种镁合金在挤压前经均匀化退火处理后所需的挤压力比未经均匀化处理的合金所需挤压力大,动态再结晶是影响其挤压力大小的决定性因素。     

螺旋伞齿轮摆动辗压成形三维有限元模拟

螺旋伞齿轮高径比小,适合摆动辗压工艺成形。采用刚粘塑性有限元对螺旋伞齿轮摆动辗压工艺进行了模拟,获得了螺旋伞齿轮的摆动辗压变形规律、金属流动规律和载荷曲线。就螺旋伞齿轮锻件脱模问题,设计出轴承式凹模,当锻件被顶出时,凹模沿齿轮轴线做同步旋转,锻件被旋出凹模。