镍基高温合金筒形件毛坯错距旋压工艺研究

GH4169镍基高温合金筒形件流动旋压成形的难点是在大长径比、变壁厚的情况下保证内径精度。论述了该件流动旋压成形的工艺路线的制定、试验方法。在旋压过程中采用了错距旋压,探索了错距流动旋压的工艺参数对尺寸精度的影响,为该类产品的旋压成形提供了技术支持。     

薄壁筒形件错距强力旋压成形的工艺研究

通过双旋轮错距强力旋压成形薄壁筒形件的工艺研究,对错距旋压过程中旋轮轴向错距值的选择、进给比、冷却、润滑进行了讨论,对旋压缺陷进行了分析,解决了旋压过程中出现的问题,达到了工件质量要求。     

气瓶旋压成形技术

与冲压、焊接结构的气瓶相比,旋压气瓶从根本上消除了与焊缝有关的不连续、强度降低、脆裂和拉应力集中等缺陷,故此,旋压气瓶的气密性和耐压性能有了大幅提高。本文重点阐述了钢质气瓶、铝合金气瓶的旋压成形工艺特点及其成形工艺规范。     

旋压制动缸的工艺研究

介绍了车辆制动缸体的旋压工艺特点，工艺方案的确定、原材料选择，普旋成形工艺参数的合理选择，采用双旋轮错距旋压成形技术对缸体进行多道次强旋成形及产品的精度分析。     

解决反旋测长的一种新方案

强力旋压机床在加工工件时根据工件的不同有两种旋压方法:对于带底的筒形件采用正旋,即金属流动方向与旋压方向相同。对于不带底的筒形件采用反旋,即金属流动方向与旋压方向相反。对于正旋,旋压成形长度与进给量一致。而对于反旋,旋压成形长度等于进给量与金属反流量之和。由于金属反流量与金属变形量有关,因而对于同一旋匝参数来说,其往往也不一致。目前,大多通过理论计算和反复实践才取得一近似值,这给实际加工和提高工件精度带来了不少困难。     

高压气瓶强力旋压工艺研究

从旋压毛坯设计、旋压后零件状态确定、旋压参数选择、旋压芯轴和旋轮的设计等几个方面,讨论某型高压气瓶瓶身强力旋压工艺。结合旋压成形试验过程,制定出合理的工艺方案。通过试验验证该工艺方案完全适应高压气瓶瓶身的加工。     

AZ31B镁合金板材旋压成形工艺研究

采用摩擦旋压成形工艺,研究了AZ31B挤压板材供应态试样在不预热的条件下直接进行旋压成形的可行性。结果表明,摩擦升温效应能迅速将坯料温度提高到200～450℃,从而提高镁合金板料的塑性变形能力,可旋压成形出最小直径为31.5mm、高度为9.22mm的镁合金碟形件。实验发现旋压成形的旋轮轴向进给量、旋轮运动轨迹、坯料旋转速度和润滑剂等对镁合金板材的旋压成形有较大的影响。当旋轮采用梳形运动轨迹、轴向进给量为0.22mm、坯料转速ω=900r/min时,采用MoS2钙基脂润滑,可获得较好的旋压成形效果。     

带轮旋压成形关键技术分析

介绍了钣制带轮的旋压成形方法和新旋压方法—铲旋成形技术。通过对旋压成形中的金属流动规律进行数值模拟分析,为工艺参数优化提供了参考。     

杯形薄壁矩形内齿旋压成形数值模拟与试验

为研究主要工艺参数对齿轮成形状况的影响规律,并为参数优化和工艺设计提供依据,基于MSC.MARC有限元分析软件,对杯形薄壁矩形内齿旋压成形工艺过程和工艺特点进行分析,从而获得旋压成形时变形金属沿轴向、径向和切向的流动规律。结合工艺试验,定量地研究了主要工艺参数对齿高成形的影响规律,并对试验中出现的各种典型缺陷进行分析,提出有效的预防和改进方法。提出将包括轮齿的切向和轴向尺寸均匀程度等作为旋压成形内齿零件的主要质量评价指标。模拟和工艺试验结果表明,矩形内齿旋压成形时,压下量在一定范围内对齿高的成形影响显著,进给比对齿高成形影响不大。当工艺参数选择不当时,可能出现表面隆起或破裂、轮齿周向错移、周向高度不均和齿槽撕裂等缺陷。     

两种薄壁筒形件旋压工艺改进中的真空热处理试验

正为了提高原材料的利用率,对30CrMnSiA钢薄壁筒形件进行了旋压成形工艺改进。在试行旋压前对坯料调质、旋压后不淬火的工艺改进方案时,对坯料进行了真空调质处理的试验。在试行旋压后淬火的工艺改进方案时,又进行了薄壁筒形件旋压后的真空淬火、井式炉淬火等工艺试验。经过试验对比,最后以旋压后真空淬火的工艺方法,取得了工艺改进试验的成功。一、零件概况一种直径较大的薄壁筒形件如附图所示,材料为30CrMnSiA钢。要求力学性能满足抗拉强度Rm≥1080MPa,伸长率A≥10%。这种筒形件原先     

金属薄壁筒体对轮旋压技术进展及应用探析

对轮旋压是成形大型高强金属薄壁筒体的关键技术。分别从塑变机理、成形精度影响与控制、组织演变与缺陷、对轮旋压设备等四方面概述了金属薄壁筒体对轮旋压技术的最新研究进展,指出时变非线性特点导致塑性流动控制困难是对轮旋压技术工程化应用的瓶颈。剖析了对轮旋压技术难点,分析探讨了其发展趋势,揭示出多源混动的对轮主动强力柔性旋压工艺对超高强金属、大尺寸薄壁筒体精密旋压成形的借鉴意义。     

Rotary ultrasonic drilling of needle-punched carbon/carbon composites: comparisons with conventional twist drilling and high-speed drilling

Refillable seamless steel gas cylinders are widely used to store and transport clean energy, such as compressed natural gas (CNG) and hydrogen. Conventional manufacturing processes have some disadvantages which bring potential hazard for the safety and reliability of cylinders. After reviewing the conventional manufacturing processes, a hot deep drawing process is recommended with solid steel billet stock. Based on this, an integral manufacturing process with cold flow forming process is proposed for large-diameter seamless steel gas cylinders to improve the performance of gas cylinders. Several cylinder properties including size error and fatigue lives are compared. The uniformity of wall thickness is further improved for gas cylinders by the integral process. The gas cylinders obtain fine surface finish, high tolerance of size, and commensurately enhanced fatigue lives. Meanwhile, the failure mode and effect analysis (FMEA) method is adopted to study the reliability of steel gas cylinders. The reliability of steel gas cylinder with cold flow forming process is compared with the conventional processes. The probabilities of most causes are ameliorated, except for the lamination that is usually resulted from wrong flow forming process parameters, e.g., high reduction rate and feed rate. As a whole, there is a marked drop in the risk priority number of the integral process. It is worth to further spread this in gas cylinder industry.     

镁合金轮毂等温挤旋成型装置的研究

通过设计挤旋成型装置,实现了镁合金轿车轮毂等温挤旋成型工艺,提高成形效率与加工精度。以有限元理论为依据,对汽车轮毂挤旋成型工艺特点进行分析,建立了符合实际要求的力学模型。采用四节点四边形单元对毛坯进行网格划分,然后对挤旋成形过程起关键作用的工艺参数:加工温度、挤旋轮半径、进给比、主轴转速进行了正交试验的数值模拟,利用方差分析各因素对指标的影响大小,优化各个工艺参数之间的配合。结果表明成型工艺可行,设计的装置具有一定价值。     

无错距强力旋压连杆衬套过程数值模拟研究

以发动机的锡青铜连杆衬套为研究对象,运用DEFORM-3D有限元软件对连杆衬套毛坯的无错距强力旋压过程进行了数值模拟。根据模拟结果,重点分析了在旋压过程中的金属流动速度规律、旋轮的受力以及毛坯的等效应力应变的分布情况。得出了旋压过程中毛坯径向和切向流动速度、大小和方向相似,与毛坯壁厚中心点的流动速度始终相反的正弦分布规律,旋轮所受径向和切向力分布相似且轴向受力最小,旋压过程中等效—应力应变主要分布在旋轮与毛坯的接触区域,远离接触区域的等效—应变较小,毛坯内部存在残余应力等。     

板坯形状对方截面无模旋压轴向可旋深度的影响

利用实验方法对比了方形和圆形板坯形状对方截面无模旋压轴向可旋深度的影响,并对其影响机理进行了理论分析。首先采用确定初始步长的方法推导了可无限扩展的方截面旋轮路径公式,在此基础上分别模拟了方形和圆形板坯的无模旋压过程,并对模拟结果进行实验验证。然后提出了轴向可旋深度的评估方法,并以此为判据,对比分析了同轴向旋压深度下圆形和方形板坯工况的后续可旋性,发现方形板坯工况优于圆形板坯工况,进而揭示其机理为：方形板坯工况旋压过程中剩余法兰形状与旋轮路径切合性较好,促进了金属径向流动均匀化。     

MULTIPOINT BLANK HOLDER FORCE CONTROL IN HYDROFORMING OF FUEL TANK

The study of multipoint blank holder force(BHF) control is carried out for hydroforming a complicated shape motorcycle fuel tank. By finite element method (FEM) simulation, the configuration of multipoint blank holder cylinders and the setting of local BHF are optimized, and the influences of the multipoint BHF on the hydromechanical deep drawing and conventional hydroforming processes are studied. The desired fluid pressure and whole BHF are predicted for hydromechanical deep drawing process. Finally, simulation results are testified by forming experiment, and they are in agreement very well.     

Study on compound spinning technology of large thin-walled parts with ring inner ribs and curvilinear generatrix

Given their rapid development, aerospace and other high-tech industries are in urgent need of process technology for large complex thin-walled shells represented by large thin-walled parts with ring inner ribs and curvilinear generatrix. To make up for the deficiency in existing forming methods, this paper presents a compound spinning process that integrates counter-roller spinning, multi-neck spinning, and hot spinning. The finite element models for the counter-roller spinning and multi-neck spinning forming of such parts are established, and these models can simulate the influences of different spinning process parameters on workpiece maximum equivalent stress and maximum ovality. The 2A12 aluminum alloy tube blank is used in this paper. The process parameters for obtaining the counter-roller spinning for such parts are as follows: a feed ratio of 1.0 mm/r and a roller nose radius of 8 mm. The process parameters of multi-neck spinning are as follows: a feed ratio of 3.0 mm/r and a roller nose radius of 80 mm; and the forming temperature of hot spinning is 200–250 °C. Verification by a compound spinning test found that the numerical simulation results are consistent with the process test results. The process parameters can be used for guiding the actual production of large thin-walled parts with ring inner ribs and curvilinear generatrix.