单体支柱用手把体模锻模

正我公司单体液压支柱中手把体原锻造工艺采用冲孔、切边两道工序,不仅占用设备台时且精度低,锻件外形加工余量大。同时由于工艺生产过程中冲孔、切边设备不同步,造成模锻锤间歇性停产、工作效率低、设备利用率低等诸多缺陷,加大该零件加工制造成本和生产同期延长。1.新工艺分析(1)复合模设计一次行程中完成冲孔和切边两道工序模     

锅炉栏杆柱冲孔设备的研制及应用

针对锅炉产品栏杆柱孔加工产能不足的问题,研制了一台栏杆柱专用冲孔设备。冲孔设备主要由冲孔模具、内支撑芯棒及伸缩液压机构、冲孔液压装置、液压站、电控柜及机架组成。为验证冲孔设备性能及冲孔效率,选用两种规格栏杆柱进行冲孔试验,以冲孔成型质量作为栏杆柱冲孔的评价指标,探究冲孔模具结构尺寸、内芯尺寸、内芯机构对冲孔效率及质量的影响,进而获得适合栏杆柱冲孔的工艺设计参数。试验表明:该冲孔设备能够实现栏杆柱Φ19 mm通孔的冲制,冲孔质量合格,冲孔效率为35秒/根,现钻孔效率为56秒/根,效率提升了37.5%;孔加工产能需求为36秒/根,故采用冲孔加工可满足栏杆柱孔加工工序的产能需求。     

U形罩冲孔翻孔复合模具设计难点

U形罩为我公司的常用零件,材料为无氧铜,料厚1mm,采用冲压加工。其冲压工艺为：落料引深一冲孔一翻孔。由于该类零件产量很大,为了提高生产效率,我们对其加工工艺进行分析,尝试设计冲孔翻孔复合模具,将冲孔、翻孔两道工序一次加工完成。图1、图2为常规工艺的冲孔、翻孔工艺图。     

多轴浪形冲孔凹模加工工艺的改进

通过改进原有的加工工艺，采用先进加工设备，提高了多轴浪形冲孔凹模的加工精度，保证了产品的及时供应，同时提高了生产效率，缩短了生产周期，节约了原材料，达到了增产节约的目的。     

拉深、压印、冲孔复合模

图1所示为变压器储油框盖,材料为2mm厚的A3钢。该零件原加工工艺是:先用拉深模具对板材进行拉深,然后再用冲孔模具对半成品零件进行冲孔。现在改用拉深、压印、冲孔复合模具一次冲压成型,从而提高了生产效率。     

长板分段冲孔加工

介绍了采用定、滑尺机构重复定位与分段冲孔的工艺,解决长板冲孔加工,中小批量和短期大批量生产的关键问题。     

角接触球轴承冲压保持架工艺优化

针对传统角接触球轴承冲压保持架工艺复杂,加工周期长,模具加工复杂,制造成本高且生产质量不稳定的问题,提出以下改进措施:将下料、拉伸、切底合为一道工序,采用偏摆料机构送料,模架采用四导柱结构;将冲孔和压坡合为一道工序,通过直线导轨式气动传动及伺服电动机带动实现自动化操作;冲孔冲头与冲孔凹模采用精密机床仿形加工.改进后工艺...     

分段冲孔工艺

在腈纶设备零件帘子网板上冲高密度分布孔是困难的，本文介绍用定尺、滑尺机构重复定位，分段冲孔并改装60t数控小孔冲床的方案，解决这一难题。一、问题的产生我厂生产各种纺织烘干设备，帘子网板的冲孔，一直是关键工序，为解决此问题，我厂自行设计、制造了60t数控小孔冲床，采用单板机控制步进电机驱动进给系统，该小孔冲床的加工行程：X坐标（长度方向）为2500mm，Y坐标（宽度方向）为1200mm，可满足一般国产钢板（尺寸为2100×1000）各种尺寸网板的冲孔加工。但在90年代与美国杜邦公司合作生产的腈纶设备中，3050×410（mm）帘子网板…     

整修模的设计及外缘整修技术的应用

如图1所示固定块是我公司某产品一关键部件，其两侧对称度要求0．15mm、表面粗糙度值Ra=6．3mm、光亮带70％以上。如按一般冲裁，根本不能达到产品要求。原加工工艺为：落料→冲孔→磨两侧。该工艺虽然能满足产品要求，但效率低满足不了批量要求，且成本较高。现将加工工艺改为：落料冲孔一修边（两次）。该工艺采用了外缘整修技术，在满足产品性能的前提下提高了生产效率，缩短了加工周期，节约了制造成本，能满足批量生产需要。     

离合器毂铣槽啃刀现象分析及对策

从设备与工艺两方面对离合器毂铣槽时出现的啃刀现象进行了分析,指出啃刀原因主要是机床丝杆局部磨损无法自动消除间隙,以及原工艺采用逆铣粗加工和切削深度过大所造成,相应提出的对策为变换装夹位置和改进加工工艺,有效地解决了生产中的难题。     

Estimation of springback in double-curvature forming of plates: Experimental evaluation and process modeling

This paper presents the results obtained from a series of experiments on double-curvature forming of 300 mm square and 15 mm thick plates of type 316L(N) stainless steel to evaluate the inherent springback and also to validate finite element method (FEM) based process model developed for forming of multiple-curvature sectors of large size vessels. The experimental results show that twisting of the plate occurs during pressing, which is unavoidable in an actual forming setup on the shop floor. Twisting increases with increase in slope of the die cavity. Springback in the plate changes in an ascending order towards the centerline of the plate from the edges. The final radius of curvature (ROC) on the pressed plate after springback does not remain constant along a particular axis although the die and the punch had constant ROC along that axis because of varying constraint to opening up of the plate from centerlines to the edges. Springback also increases with reduction in the stiffness of the die and punch. The simulated plate profiles obtained from the FEM process model for multiple-curvature plate forming compared well with the experiments, the maximum error being within 6%. The process model used a sequential dynamic explicit formulation for the plate pressing phase and a static implicit formulation for the unloading (springback) phase in the Lagrangian framework. Reduced integration shell elements were used for the plate and the die and the punch were considered rigid. Dynamic explicit FEM for pressing and static implicit FEM for the unloading phase are adequate and economic for modeling of plate forming process by using FEM. The necessary material and frictional property data needed for the FEM process model were generated in-house. This model can be applied to design of dies and punches for forming the petals of large pressure vessels. The FEM process model predicts the final shape of the product and the residual cold work level for a given die, punch and plate configuration and this information can be used to correct the die and punch shapes for springback to manufacture the petals to the desired accuracy.     

A study on thick plate forming using flexible forming process and its application to a simply curved plate

In this study, design and fabrication of a flexible forming machine are carried out for the purpose of manufacturing a prototype of curved plate block for hull structure used in shipbuilding industry. Flexible forming dies which consist of numbers of punches in an array form for upper and lower sides are designed in view of thick plate forming. A punch has formation of male and female screws to adjust its length with regard to a given surface, and all punches are supported by each other in punch housing. Software for process configuration and punch control are developed to operate the novel flexible forming machine. The software are composed of the punch height calculation part which uses an offset surface scheme. Prior to manufacturing of a prototype, numerical simulations for a saddle-typed thick plate forming process including metal forming and spring-back analyses are carried out to predict the forming performance. Experiments are also carried out to validate and confirm the feasibility of flexible forming technology in view of practical application of thick plate forming process. Curvature radii observed in the simulation and experiment are investigated and compared. Consequently, development and practical application of flexible forming technology to the thick plate forming process are described from design of the forming machine to manufacturing of the prototype. It is confirmed that the flexible forming technology suggested in this study has enough feasibility in new application of thick plate forming in shipbuilding structures which has been formed through expensive and laborious conventional line heating.     

有限元网格孔洞的自动填充算法

本文介绍了一种利用网格孔洞的边界元而有效填充网格孔洞的算法。由于在孔洞的修补过程中 ,修补网格的信息不完整 ,所以 ,修补后的网格形状很大程度上依赖于修补算法和初始信息的确定。本文阐述了一种简单而有效的网格孔洞的修补算法。用该算法所生成的网格保持了在孔洞边界的光滑过渡 ,并可以满足一般机械制造工程上的需要 ,在快速原型制造、有限元分析中有重要的实际应用价值。     

Simulations of the transient flow generated from a started flat plate

Transient operations are commonly founded in fluid machineries such as the starting, stopping, and variations of rotor speeds, etc. Flow generated from a started flat plate is of fundamental importance. Experiments have been done to observe the flow evolution in current researches. And in order to explore the flow in more detailed scale, some vortex methods with high resolution and other numerical methods were developed to solve various related problems by some researchers. But the promotion of vortex method to engineering application is rare due to its complexity and difficulty in specifying the boundary conditions. In order to build up a method of numerical study for such problems, a simplified model is built up with a flat plate. The development of two-dimensional viscous incompressible flow generated from an impulsively started and uniformly accelerated infinitesimally thin flat plate is simulated numerically. A dynamic mesh(DM) method based on the spring analogue and local remeshing is applied to realize the mesh motion caused by the started plate. Researches show that the mesh quality will decline under large grid shear force during the updating process. To conquer this problem, a region near the plate is separated to guarantee the mesh quality at location of interest which is the innovation of the present paper. All computations at least cover a period during which the plate translates 6 times its length. The simulated instantaneous velocity profiles, flow structures and drag coefficients under several Reynolds numbers (20 Re 126) and accelerations (20 m/s2 a 152 m/s2) are presented and compared with existing results in literatures. Comparisons are found to be satisfactory, confirming the validity of the current proposed method(region separated DM). The proposed DM method is firstly used to study the transient flow generated from a started flat plate and can be used in further study of transient characteristics during transient operations of turbo machineries.     

侧向槽粉末制品压制成型工艺

叙述了YAN79Z-B型模架全自动干粉成型液压机压制工艺的设计，在压制粉末冶金侧向槽过程中，阴模与浮动冲上升到设定位置，送粉器前移对阴模腔内充满粉料后，上冲下行到阴模内向下压制时，利用阴模与浮动冲的同步浮动，压制到终了位置产品成型，然后阴模拉下，浮动冲微升推出产品，实现了侧向槽产品国产化，自动化生产。     

铝合金自冲铆工艺参数的多元非线性回归模型

建立有效、可靠的自冲铆工艺及力学性能预测模型是其工业应用推广过程中亟待解决的一个重要问题。选取AA5182、AA5052和AL1420三种铝合金薄板材料,基于Box-Behnken Design(BBD)响应面法开展了铝合金自冲铆连接试验研究。以板厚、板材硬度和铆钉硬度为三参数输入条件,以冲头行程、最大冲压力和失效载荷为输出响应值,建立影响因素与响应值之间的回归模型,探究多种输入参数对响应值的影响规律。试验结果表明:依据回归模型得到的工艺和强度理论预测值与试验值之间的误差在8%以内,建立的回归模型具有较高的工程应用可靠性。通过三维响应面和等高线分析表明,板厚和铆钉硬度的交互作用对最大冲压力和失效载荷的影响最大,冲头行程主要受板材硬度和铆钉硬度的交互影响。     

Investigation of sheet metal forming by bending—Part IV: Bending and wrinkling of circular sheets pressed by a hemispherical punch

This paper reports on an investigation of the bending forming processes in circular sheets pressed by a hemispherical punch into a conical die. Both theoretical and experimental considerations are provided. It is pointed out that the deformation mechanism of such a circular plate is different from that of the workpiece in the conical die cup test studied previously in part III of this series [Int. J. Mech. Sci.31, 327–333 (1989)]. The theoretical analysis shows that a central gap appears between the plate and the hemispherical punch at small deflections and disappears when the punch force increases beyond a certain magnitude. It is then shown that the previous approximate analytical treatment of the distribution of punch force is no longer appropriate to the wrinkling of the plate. It is shown that, as in the case of the conical die cup test, the circumferential wave number for the wrinkling mode corresponding to the critical wrinkling load of the present workpiece is four. In addition, the paper reveals that a doubling of the wrinkling wave may occur in the first stage of the forming process.     

Fabrication of micro-channel arrays on thin stainless steel sheets for proton exchange membrane fuel cells using micro-stamping technology

Bipolar plates are one of the crucial components of proton exchange membrane fuel cells. Because of the expensive production costs of traditional graphite bipolar plates, which require a few millimeters thickness over the space, the resulting metal bipolar plate reduces the cost, and the thickness can be reduced to the micron range. This study explored the application of micro-stamping technology to produce thin metal bipolar plates with the relevant process parameters. In this study, the channel design was 0.8?×0.75 mm for the use of a rigid punch on a 50-μm-thick stainless steel sheet (SUS 304) for micro-channel stamping processes. The finite element method and the experimental results were used to analyze the main parameters of the micro-stamping process. The traditional material model and the scale factor modified material model were used for simulation. The experimental results verified that the modified material model is more realistic for products and has superior similarity because the punch load is relatively small. This study used updated Lagrangian formulation concept to establish an elastic–plastic deformation finite element analysis model and scale factor to modify the calculation to effectively simulate the micro-stamping process for metal bipolar plates.     

Fast thickness prediction and blank design in sheet metal forming based on an enhanced inverse analysis method

In sheet metal forming process, inverse analysis codes serve a useful purpose at the early product design stage when an approximate analysis is required to determine if the initial concept part can be made and where the failures and defects will occur. In this paper, a robust energy-based 3D mesh mapping algorithm is used to obtain the initial solution and is followed by a reverse deformation method to improve its accuracy. The novel initial solution scheme can consider the material and the process parameters, and thus lead to fewer Newton–Raphson iterations. The actions of the punch, die, blank holder and the drawbead are fully considered. A fast and reliable boundary condition treatment method is implemented to workpiece without binder and addendum information. Contact treatment between punch and die is an essential issue which greatly affects the convergence of Newton–Raphson iterations. A reliable contact treatment based on topological relations of workpiece is proposed to define the force direction between die and punch. Equivalent drawbead forces are also considered with a simplified model. With the improved aspects, the in-house inverse analysis code InverStamp is developed. Application to a square box and a clover-shaped cup are presented with demonstrations of the validity of the code and the efficiency of the proposed modified approaches.     

Fault identification method for planetary gear based on DT-CWT threshold denoising and LE

Planetary gear is widely used in large-scale complex mechanical systems. However, because of the particularity of planetary gear transmission, serious wear and fatigue crack failures often occur in the sun gear, planet gears, and inner gear ring. In addition, every type of fault will experience different degradation processes. Improving the operation reliability of mechanical equipment through fault diagnosis of planetary gears and monitoring their degradation process is beneficial. This paper proposes a planetary gear fault identification method based on Dual-tree Complex wavelet transform (DT-CWT) threshold denoising and Laplacian eigenmaps (LE). The noise reduction processing of the original signal is achieved by the DT-CWT threshold denoising method, which takes full advantage of DT-CWT and is combined with the wavelet threshold of rigrsure principle. The original high-dimensional feature set, including the time domain features, frequency domain features, permutation entropy, and fractal box dimension of the denoised signal, is constructed from multi-angles. To solve the problems of excessively large feature dimension and the existence of redundant information, the LE algorithm is used to reduce the dimension of the original high-dimensional feature set, and the low-dimensional sensitive features are obtained. Through the above method, the effective identification of different fault states and different degradation states of the planetary gear are achieved.