Research on the Casting-forging Precision Forming Process of Alternator Poles

The casting-forging combined technique and the closed die forging without flash-less are both new developed material working methods. The former can not only decrease forming operations of forgings, but also increase the material utilization ratio. Therefore, it is applied to produce more complex forgings. The latter is required for forging precise parts without burrs. The alternator pole is a complex forging, which was usually produced by hot forging, upsetting-extrusion or upsetting-extrusion and bending processes. During these processes, not only the forming force is higher, but the material of burrs accounts for 30 percent or so of total required material. And burrs are difficult to remove in the sequential machining process. In accordance with defects exiting in current manufacturing of alternator poles by upsetting-extruding process, such as more material demand, higher forming force and difficulty of next machining, a casting-forging precision process of alternator poles was developed and investigated in this paper. In the process, the pole was formed by two operations. One is the pre-forming operation by casting. The other is the final forming operation by the closed precision forging process. This can not only shorten processes, decrease material and power demand, but also increase precision of forgings. First, the casting blocker was designed considering the casting process and the forging ratio and the mode of deformation. Then the die structure for closed precision forging was designed, and the closing device for forging dies with spring assemblies in order to provide the necessary closing force was also designed. Finally the forming processes was investigated by test and numerical simulation method to optimum process parameters and die structure design parameters. The result can provide basis for applying the process to manufacture poles in practice.

Analysis and Optimization on Factors Affecting Forming Quality of Half Axle Gears Warm Precision Forging

Half axle gears is produced by precision forging popularly because of the advantages in minimum machining allowances, lower material consumption and good service properties. But the forming quality of precision forging is difficult to control. Many simulations and analysis of precision forging process were taken by previous researchers. But no concrete method is proposed to evaluate and optimize the forming quality of half axel gears. The primary purpose of this work is improving the forming quality of half axel gears by analyzing and optimizing the affected factors of forming quality. The enclosed-die warm forging process of half axle gears was developed, and a new type of die-set used on double action hydraulic press was brought forward. The main influential factors of precision forming quality were analyzed after the forming process had been simulated by using finite element method（FEM）. These factors include die structure, web thickness and web position. A method used to evaluate the forming quality was established, which investigated the maximal forming load, the metal filling rate and the material damage factor. The FEM simulations of half axle gears precision forging were evaluated by this method. The results show that the best forming quality can be achieved when the punches were added with bosses, the web located at the middle plant of the gear, and the web thickness was 30 percent of the inner hole diameter. Verification experiments taking the above optimized parameters were performed on a 7.8 MN double action hydraulic press. The trial products were formed well. And their geometric precision meets the demand. The verification result shows that the optimization of the influential factors, according to the simulations and the evaluation method, can improve the forming quality. The new structure of precision forging die-set and the new evaluation method guarantee a high forming quality ofhalfaxel gears.

Forming-Precision-Driven Structure Design of Hydraulic Press: Methodology and Case Study

The structure stiffness of presses has great effects on the forming precision of workpieces, especially in near-net or net shape forming. Conventionally the stiffness specification of presses is empirically determined, resulting in poor designs with insufficient or over sufficient stiffness of press structures. In this paper, an approach for the structure design of hydraulic presses is proposed, which is forming-precision-driven and can make presses costeffective by lightweight optimization. The approach consists of five steps:(1)the determination of the press stiffness specification in terms of the forming precision requirement of workpieces;(2)the conceptual design of the press structures according to the stiffness and workspace specifications, and the structure configuration of the press;(3)the prototype design of the press structures by equivalently converting the conceptual design to prototypes;(4)the selection of key structure parameters by sensitivity analysis of the prototype design; and(5)the optimization of the prototype design. The approach is demonstrated and validated through a case study of the structure design of a 100 MN hydraulic press.

Effect of Deformation Condition on Axial Compressive Precision Forming Process of Tube with Curling Die

The effect of the deformation condition on the axial compressive precision forming process of tube with curling die was investigated by using a rigid-plastic FEM. The results show that the forming accuracy depends mainly on geometric condition rp/d0, little on tube material properties and friction condition; the relative gap △/2rp of double-walled tubes obtained decreases with Increasing rp/d0, and there is a parameter k for a given to/do or rp/t0, when rp/d0 >k, △/2rp< 1, otherwise △/2rp>1.

Variation analysis ofprecision mechanical assembly consideringform errors and local deformation

A method to analyze the effect of form errors and local deformation on the assembly accu- racy and its stability in a non-rigid assembly system is proposed. The contact finite element method was used to obtain local deformation of mating surfaces, which was superposed onto form errors to obtain real mating surface data of assemblies. Then mating variation was obtained by establishing vir- tual contact planes. Finally, an experiment of the assembly of two cylindrical components was car- ried out to verify the validity of the proposed method. By comparing the calculation accuracies of 3D assembly with and without taking into account local deformation, the results showed that the effects of local deformation of mating surfaces on calculation accuracy of mating variation was not neglect- able compared with form errors.

Effective tool design of three-rank form as precision removal-process of ITO thin-films

A new effective tool design of three-rank form of electroremoval was present using a precision recycle system offering faster performance in removing the indium-tin-oxide(ITO) thin-films on color filter surface of displays. Higher electric power is not required since the three-rank form tool is adopted as a feeding mode to reduce the response area. The low yield of ITO persists throughout the entire semiconductor production process. By establishing a recycle process of ultra-precise removal of the thin-film nanostructure, defective products in the optoelectronic semiconductors industry can be effectively recycled, decreasing both production costs and pollution. A 5th generation TFT-LCD was used. The design features of the removal processes for the thin-films and the tool design of three-rank form were of major interest. For the precision removal processes, a pulsed current can improve the effect of dreg discharge and contributes to the achievement of a fast workpiece (displays' color filter) feed rate, but raises the current rating. High flow velocity of the electrolyte with a high rotational speed of the tool electrodes elevates the ITO removal effect. A displays' color filter with a fast feed rate is combined with enough electric power to provide highly effective removal. A small thickness of the rank and a small arc angle of the negative-electrode correspond to a higher removal rate for ITO-film. An effective three-rank form negative-electrode provides larger discharge mobility and better removal effect. It only needs a short period of time to remove the ITO easily and cleanly.

Automatic Judgement on Form-Position Precision Grade of Features

Based on GB/T1184-1996, four form-position tolerance tables are listed on the appendix B. The regularity of distribution for form-position tolerances is deliberately analyzed. This paper describes a formulated method for identifying the precision grade, deduces the functional relation formulae between the tolerance and its precision grade, and further confirms the automatic judgement method presented by a practical program on PC computed

Precision Design for Machine Tool Based on Error Prediction

Digitization precision analysis is an important tool to ensure the design precision of machine tool currently. The correlative research about precision modeling and analysis mainly focuses on the geometry precision and motion precision of machine tool, and the forming motion precision of workpiece surface. For the machine tool with complex forming motion, there is not accurate corresponding relationship between the existing criterion on precision design and the machining precision of workpiece. Therefore, a design scheme on machine tool precision based on error prediction is proposed, which is divided into two-stage digitization precision analysis crucially. The first stage aims at the technology system to complete the precision distribution and inspection from the workpiece to various component parts of technology system and achieve the total output precision of machine tool under the specified machining precision; the second stage aims at the machine tool system to complete the precision distribution and inspection from the output precision of machine tool to the machine tool components. This article serves YK3610 gear hobber as the example to describe the error model of two systems and basic application method, and the practical cutting precision of this machine tool achieves to 5-4-4 grade. The proposed method can provide reliable guidance to the precision design of machine tool with complex forming motion.

Springback of thin-walled tube NC precision bending and its numerical simulation

The springback is one of the key factors which affect the forming quality of thin-walled tube NC precision bending. The elastic-plastic finite element method was proposed to study the springback process of thin-walled tube NC precision bending and the combination of dynamic explicit algorithm and the static implicit algorithm was proposed to solve the whole process of thin-walled tube NC precision bending. Then, the 3D elastic-plastic finite element model was established based on the DYNAFORM platform, and the model was verified to be reasonable. At last, the springback rule of thin-walled tube NC precision bending and the effect of geometry and material parameters on the springback rule of thin-walled tube NC precision bending were studied, which is useful to controlling the springback of thin-walled tube NC precision bending, and the numerical simulation method can be used to study other effect of parameters on the forming quality of thin-walled tube NC precision bending.

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 process parameters and applied in the automotive industries.The results show that the hot compression of AZ80 magnesium alloy has the peak flow stresses of pre-strained alloy with finer grain,which are lower by 20%than those of as-cast alloy under the same deformation conditions.The forming load is related to contact area and average positive stress on interface during forging process.

Thin-walled aluminum alloy tube NC precision bending based on finite element simulation

Elongation and springback are the bottleneck problems of thin-walled aluminum alloy tube NC precision bending. So thin-walled aluminum alloy tube NC precision bending based on finite element simulation is put forward. The finite element model of thin-walled aluminum alloy tube NC bending is established based on the DYNAFORM platform. The process of thin-walled aluminum alloy tube NC precision bending is simulated with the model and the elongation and springback of tube bending can be gained. A new method of measuring the elongation of thin-walled tube NC precision bending named 'pressure die measuring method' is put forward and the computing equations of bending angle, bending radius, blanking length and initial bending section based on elongation and springback angle are derived. The bending angle, bending radius, blanking length and initial bending section of tube bending can be gained with these equations based on the elongation and springback angle from the simulation. The study can be used to control the quality of thin-walled aluminum alloy tube NC bending so that precision bending without redundance can be realized.

基于形色筛选的苹果园羽化害虫粘连图像分割方法

针对苹果园害虫识别过程中的粘连问题,提出了一种基于形色筛选的害虫粘连图像分割方法。首先,采集苹果园害虫图像,聚焦于羽化害虫。害虫在羽化过程中已完成大部分生长发育,其外部形态、颜色、纹理更为稳定显著。因此,基于不同种类害虫的形色特征信息分析,来获取害虫HSV分割阈值和模板轮廓。其次,利用形状因子判定分割粘连区域,通过颜色分割法和轮廓定位分割法来实现非种间与种间粘连害虫的分割。最后,对采集的苹果园害虫图像进行了试验分析,采用基于形色筛选的分割法对单个害虫进行分割,结果表明,本文方法的平均分割率、平均分割错误率和平均分割有效率分别为101%、3.14%和96.86%,分割效果优于传统图像分割方法。此外,通过预定义的颜色阈值,本文方法实现了棉铃虫、桃蛀螟与玉米螟的精准分类,平均分类准确率分别为97.77%、96.75%与96.83%。同时,以Mask R-CNN模型作为识别模型,平均识别精度作为评价指标,分别对已用本文方法和未用本文方法分割的害虫图像进行识别试验。结果表明,已用本文方法分割的棉铃虫、桃蛀螟和玉米螟害虫图像平均识别精度分别为96.55%、94.80%与95.51%,平均识别精度分别提高16.42、16.59、16.46个百分点。这表明该方法可为果园害虫精准识别提供理论和方法基础。

齿轮精密塑性成形理论技术装备研究与应用

齿轮是传动系统的核心基础件,被广泛应用于机械、汽车、航空航天装备等领域。齿轮传统制造技术为切削加工,其材料利用率低、加工周期长,特别是金属流线切断,损害齿轮性能,无法满足高端装备发展需求。齿轮精密塑性成形制造技术具有节能、节材、高效和优质等特点,是高性能齿轮技术发展方向。阐述了齿轮精密塑性成形理论方法,分析了国内外圆锥直齿轮、圆柱直齿轮和圆柱螺旋/斜齿轮精密成形技术特点;介绍了齿轮精密成形典型装备及产线,总结了齿轮无切削摆辗精密成形和锻造精密成形应用情况。此外,展示了圆锥螺旋齿轮多自由度包络成形和非圆齿轮锻造成形新方法,为高性能齿轮无切削成形制造技术装备研究与应用提供了参考。

集成式轴承状态实时监测系统设计

为了满足航空发动机高速轴承状态实时监测的迫切需求,研制了一种基于以太网传输的集成式多通道同步在线监测系统。系统集成了电涡流传感器前置器和IEPE加速度支持单元,满足了35~4400 MHz范围内感应探头激励和IEPE供电需求,实现转速和振动传感信号高精度采集,并通过硬件抗混叠滤波和滑动滤波算法抑制轴承的杂散干扰。试验结果表明:系统在0~9000 r/min范围内保持架转速测量误差小于2 r/min,相对误差小于0.1%,振动灵敏度为200 mV/g,实时性能好,实现轴承状态的实时在线监测。

修形斜齿轮成形磨削中齿廓精度补偿方法

建立了斜齿轮齿廓修形的坐标方程与成形磨削砂轮修整的几何算法,优化出齿廓修形后的砂轮截面廓形;通过数值模拟分析,得到了机床位置误差与齿廓偏差之间的耦合关系;编制了成形磨削齿廓精度调整软件,计算出斜齿轮修形与之对应的成形砂轮廓形和齿廓精度调整参数。通过修形斜齿轮的成形磨削试验,验证了砂轮廓形修整的正确性和齿廓精度调整的有效性。

脉冲电流对超薄316L板微流道成形精度的影响

目的研究在金属双极板脉冲电流辅助冲压工艺中,将脉冲电流单独作用于保压阶段、冲压阶段以及作用于整个冲压过程(冲压阶段+保压阶段)3种通电方式对极板流道深度及壁厚分布的影响。方法以316L不锈钢薄板作为实验材料,调节流经样品的电流参数,分别为0、10、20、30 A,分析脉冲电流参数和通电方式对极板流道深度及壁厚分布的影响规律。结果在高电参数下,当采用在冲压阶段通电、在保压阶段断电的方式2时,在保压阶段可促进应力松弛,具有最佳的回弹抑制效果,其成形深度回弹可减小73.88%。在不同电参数下,3种成形方式对双极板流道壁厚分布具有相似的影响。槽顶和槽底的壁厚减薄相对较小,减薄量为原板材厚度的2%~6%;流道直壁壁厚减薄为原板厚度的9%~15%;而外圆角和内圆角区域的壁厚减薄较大,达到27%~30%。结论在金属双极板脉冲电流辅助冲压工艺中,以不同方式施加脉冲电流,均可以显著提升流道深度,对壁厚影响并无明显差别。特别地,采用在冲压阶段通电、在保压阶段断电的方式2可以显著提升对流道回弹的抑制效果。

GH2132高温合金本构模型及大断面收缩率楔横轧成形研究

采用Gleeble-3800热模拟试验机对GH2132高温合金进行等温恒应变速率压缩实验,获取该合金在变形温度900~1100℃、应变速率0.01~10 s^(-1)范围内的真应力-应变曲线。对所得流动应力曲线进行摩擦与绝热修正,以消除试样热变形过程的绝热温升效应以及和砧子与试样间接触摩擦作用对实验结果的影响后,建立了考虑应变补偿的Arrhenius型本构模型。误差分析结果表明,其相对平均绝对误差不超过7%,可用于该合金高温变形行为研究。分析了具有大断面收缩率特征的GH2132合金楔横轧轧件的成形过程模拟,进一步验证了所建本构模型的准确性,为GH2132高温合金楔横轧工艺开发奠定了基础。

基于自由曲面光学元件的大视场光学成像系统

面向机载探测系统大视场光学成像的需求,开展了大视场光学成像系统光学设计、自由曲面光学元件超精密加工、形位误差同步检测以及系统集成与成像实验研究。首先,采用视场扩展法进行大视场自由曲面离轴反射光学系统的设计;其次,进行铝合金自由曲面反射镜纳米精度加工和高频抑制工艺探索,并实现了基于计算全息元件的自由曲面形位高精度检测;最后,进行了光学系统的装调集成与成像实验。结果表明,系统的视场角为30°×5°,全视场光学传递函数值大于0.7,接近衍射极限,最大像元均方根半径为2.075μm,自由曲面光学元件的面形精度均方根(Root Mean Square,RMS)值优于20 nm,位置精度优于1μm,装配集成后能够满足大视场高分辨的场景使用要求,同时具备稳定可靠和快响制造等特点。

基于DEFORM-3D的外凸台内齿圈件正交试验法工艺优化研究

采用刚粘塑性有限元法对外凸台内齿圈件精密成形过程进行了数值模拟,得出了成形过程中成形力规律,列出了影响成形力的两个因素:温度和凸模速度。通过正交试验法研究了各因素对成形力的影响,找到了最佳组合。研究结果有利于成形工艺的优化设计。