Type Synthesis for 4-DOF Parallel Press Mechanism Using G_F Set Theory

Parallel mechanisms is used in the large capacity servo press to avoid the over-constraint of the traditional redundant actuation. Currently, the researches mainly focus on the performance analysis for some specific parallel press mechanisms. However, the type synthesis and evaluation of parallel press mechanisms is seldom studied, especially for the four degrees of freedom（DOF） press mechanisms. The type synthesis of 4-DOF parallel press mechanisms is carried out based on the generalized function（GF） set theory. Five design criteria of 4-DOF parallel press mechanisms are firstly proposed. The general procedure of type synthesis of parallel press mechanisms is obtained, which includes number synthesis, symmetrical synthesis of constraint GF sets, decomposition of motion GF sets and design of limbs. Nine combinations of constraint GF sets of 4-DOF parallel press mechanisms, ten combinations of GF sets of active limbs, and eleven combinations of GF sets of passive limbs are synthesized. Thirty-eight kinds of press mechanisms are presented and then different structures of kinematic limbs are designed. Finally, the geometrical constraint complexity（GCC）, kinematic pair complexity（KPC）, and type complexity（TC） are proposed to evaluate the press types and the optimal press type is achieved. The general methodologies of type synthesis and evaluation for parallel press mechanism are suggested.

Effect of Si Content on Mechanical Properties of a Mo and V Free Low Alloy Cast Steel for Automobile Cold Pressing Die

The effects of Si content on combinations of important properties such as hardness, hardenability, and weldability in addition to strength increment were systematically investigated to develop a Mo and V free low alloy cast steel for automobile cold pressing die insert. For the evaluation of the applicability as the die insert, the mechanical properties were measured after spheroidization annealing （SA）, quenching and tempering （Q/T）, and flame hardening （FH） treatments, respectively. The developed 0.8%-1.6%Si containing Mo and V free alloy cast steels showed excellent matrix strengthening effect, hardenability, and weldability, fulfilling the industrial criterion of the mechanical properties for the die insert.

Microstructure and properties of nano-TiN modified Ti(C,N)-based cermets fabricated by powder injection molding and die pressing

Powder injection molding （PIM） and die pressing were employed to fabricate nano-TiN modified Ti（C,N）- based cermets. The shrinkage behavior, microstructure, porosity, and mechanical properties of the samples with and without nano-TiN addition fabricated by PIM and die pressing were analyzed. It is demonstrated that for either PIM or die pressing, the porosities are obviously reduced, the mechanical properties are significantly improved after adding nano-TiN, and the hard particles are refined; the rim phase thickness obviously becomes thinner, and the number of dimples in fracture also increases. Compared the samples fabricated by die pressing, it is difficult for PIM to obtain dense Ti（C,N）-based cermets. Due to the too much existence of pores and isolated carbon, the mechanical properties of the sintered samples by PIM are inferior to those of the sintered ones by die pressing.

Visualization Simulations for Cold Press Die

Pressing process is a manufacturing method that obtained work piece with certain dimension, shape and capability through die forcing roughcast to produce plastic deformation or separate. This paper focuses on the key problems of visualization simulation in pressing die. The final aim is that numerical simulation system can simulate the process of processing forming technique, which can supply some necessary and accurate key parameters for die design. The detail description of mechanical characteristic and key technique of sheet forming technique is discussed. Pressing forming method is one of the most important forming techniques of metal forming, which has special mechanical characteristics. The character of sheet pressing forming is that the deformation of thickness direction is very small in contrast to other directions. The deformation mode of sheet forming mainly has the following kinds: bi-directional stretch, plane stress, stretches, depths extend, bending and counter-bending. The essence of press forming is the transferring course that the transferring region of rough comes to deformation by outside force, which is main researching principle in forming and the transferring field. The analysis of pressing forming course, disclose the feature of stress-strain and their changing rule, then pressing process and forming parameters could be obtained. So the states of force and deformation of transferring region is key to determine character about the varieties of pressing transferring. The paper analyzes these factors, which may influence forming precision in pressing process. In traditional methods, some key parameter such as spring-back, bending radius for die design are calculated by experience formula or select from data table. The paper brings forward the calculation methods of key parameter in the case of drawing finite element method and numerical simulation into pressing die design. In order to calculate the value of key parameters based on data supplied by FEM, a numerical simulation application is finished combined with two descriptions of work piece deformation NURBS and discrete piece. The numerical simulation is programmed on Microsoft Visual C++ with OpenGL as the graphics tool. It establishes numerical simulation program, dynamically simulates the process of sheet pressing figuration, and gets good effects.

Humanoid Based Intelligence Control Strategy of Plastic Cement Die Press Work-Piece Forming Process for Polymer Plastics

The plastic cement belongs to a sort of polymer material, the chemical composition is very complex, and the plastic cement work-piece is generally manufactured by die press forming. Aimed at being difficult to control in parameters of forming process, the paper explored the humanoid based intelligence control strategy. In the paper, it made the anatomy in control puzzle resulted in uncertainty such as chemical component of plastic cement etc., summarized up the characteristic of cybernetics in forming process, researched on the humanoid based intelligence control strategy, and constructed the control algorithm of forming process in plastic cement work-piece. Taking the process experiment of temperature and pressure control as an example, it validated the good dynamic and static control quality through simulation of control algorithm constructed in this paper. The experimental results show that the control algorithm explored in this paper is reasonably available.

New Model Die Set for PET Plastic Jet-Moulding Machine

At the China International Food Packing Machinery Exhibition, the new model die set for PET plastic jet-mouldingmachine developed by the Zhejiang Province Taizhou Municipality Huangyan Sanyou Plastics Factory attracted the attention of numerous domestic and foreign clients. They rushed to the stand in great numbers for consultation and talks on ordering. According to the evaluation of the experts concerned, the die set is the most advanced one nationwide for PET plastic jet-moulding machinery.

Compressive behavior of NiAl/(Cr,Mo)Hf alloy prepared by high-pressure die casting and hot isostatic pressing

The NiAl-28Cr-5.85Mo-0.15Hf alloy was prepared by high-pressure die casting (HPDC) and subsequent hot isostatic pressing(HIP), and tested for compressible strength and fracture behavior at 300-1 373 K. The results show that the elevated temperature 0.2% compressible yield strength as well as the room-temperature compressible fracture strain of as-HIP alloy are larger than those of the same alloy prepared by directional solidification (DS). It suggests that the fine structures with a homogeneous distribution of fine Cr (Mo) and Hf-rich phase created by high-pressure die casting lead to these improvements.

基于PressCAD的冷冲模具设计

针对冷冲模具设计由设计思想到图纸表达的耗时性和易错性,介绍基于PressCAD软件的冷冲模设计方法。由于PressCAD参数化设计的特点,用户只需要把握设计的结构和参数,设置好设计数据之后,装配图、零件的各种加工图就可以通过它自动生成出来,可节约大量劳动成本和时间。

基于PressCAD的冲孔、落料复合模具设计

介绍了基于PressCAD进行冲孔、落料复合模具设计的流程、参数设置及设计方法。绘制刃口、模板及模座轮廓后进行模具资料设定,系统能自动绘制模板俯视图及侧视图,手工完善侧视图及俯视图后,可以快速分离模板并自动标注。使用PressCAD进行冲孔、落料复合模具设计,既提升设计效率,又可减少设计失误。

基于PressCAD的冲孔模具设计

基于PressCAD进行冲压模具设计可大大提升设计效率,有效减少设计失误。但相关文献对此涉及较少。本文就介绍基于PressCAD进行冲孔模具设计的流程、参数设置及设计方法。

基于PressCAD的冲孔模设计

基于PressCAD进行冲压模具设计可以大大提升设计效率,也可以有效减少设计失误,但相关文献却比较少涉及到。介绍了基于PressCAD进行冲孔模具的流程、参数设置及设计方法。

Numerically controlled bending performance of medium strength TA18 titanium alloy tubes under different die sets

The rapid development of aviation and aerospace technologies has led to increased interest in the application of numerically controlled(NC) technology for bending light-weight titanium alloy tubes.In order to study and develop advanced NC bending technology,it is necessary to understand the bending performance of medium strength TA18(Ti-3Al-2.5V,ASTM Gr.9) titanium alloy tubes during NC bending under different die sets.This paper focuses on the bending performance of medium strength TA18 tubes under different NC bending die sets,including the variations in the stress,strain,wall thickness,cross sectional deformation,and defects.The results show that adding a wiper die to the base die set decreases the radial,hoop,and tangential compressive stress and the tangential compressive strain,and adding a mandrel to the base die set also decreases these stresses,but increases the radial and hoop tensile stress and decreases the hoop compressive strain obviously,and brings about a three-dimensional tensile stress concentration where the mandrel provides support.For the NC bending of medium strength TA18 tubes,the flattening of cross section is more sensitive index than the thinning of wall thickness.Introducing a mandrel can improve the flattening of cross section obviously but it has a little worse effect on the thinning of wall thickness,and adding a wiper die to the base die set can inhibit the occurrence of the inside bulge but worsen the flattening of the cross section remarkably.Considering the above effects of the mandrel and wiper die on bending performance,it is reasonable to apply the die set comprising a bending die,clamp die,and pressure die for tubes with a small diameter and the die set including an appropriate mandrel additionally for tubes with a larger diameter,in order to bend the medium strength TA18 tubes with high quality and at low cost.

Effects of TiCN Composite Die with Low Thermal Conductivity on Hot Forging Performances

Titanium carbonitride based composite （TiCN-metallic binder） was developed as die material for replacement of cemented tungsten carbide. The effects of thermal conductivity characteristic of the TiCN composite on hot forging performances were investigated using a servo press with ram motion control. Three types of the die materials; （a） tool steel for hot working, （b） cemented tungsten carbide with high thermal conductivity and （c） TiCN composite with low thermal conductivity were compared. In hot upsetting of a chrome steel workpiece, the TiCN composite die was confirmed to reduce the forging load by approximately 20% at slow forging speed. This is because the die with low thermal conductivity could prevent the workpiece from rapid cooling induced by heat transfer at the die-workpiece interface. In addition, the material flow of the workpiece to a die cavity was improved. Furthermore, the wear depth/wear coefficient of the TiCN composite was lower than that of the tool steel and the cemented tungsten carbide in the numerical analysis of wear due to the combination of low thermal conductivity and high hardness.

FROM THE CHINESE PRESS

Dr. Zhao Honored Dr. Zhao Xuefang is in charge of the Obstetrics/Gynecology Department of the Changzhi City People’s Hospital in Shanxi Province. On April 23, 1994, she received from the hands of Qian Zhengying, Vice-Chairman of Chinese People’s Political Consultative Conference, the first Norman Bethune Medal, granted by the Ministry of Public Health and the Ministry of Labor and Personnel. Since Dr. Zhao began working in the medical field in 1963, she has continued to improve her techniques. After more than 30 years in medicine, she has treated thousands of patients without incident. Though Dr. Zhao has been diagnosed with cancer and has had two operations, she has continued to heal the wounded and rescue the dying. Her only wish is to relieve the pain of more patients as long as she can. —China Women’s

基于SET-AHP-FBS的液压式压合机设计

为解决现有液压式压力机产品设计开发流程过程繁琐,且创新性不足的问题,文章构建了基于SET-AHP-FBS的设计策略。通过SET分析法找到产品创新设计的必要性及设计缺口,利用AHP分析用户需求权重,基于FBS进行“需求—行为—结构”的映射,将用户需求转化为结构设计参数,得到液压式压合机的系统方案设计。借助李克特量表对设计方案进行有效性验证。研究表明,基于SET-AHP-FBS的设计策略可以有效地减少设计过程中主观因素的影响,提升产品的创新性。

对辊制粒机压辊的有限元分析及优化

对辊制粒机的压辊在工作过程中由于受交变载荷作用寿命往往较短,为改善压辊受力状况,根据对对辊制粒机制粒成型过程的分析以及对压辊受力状况的研究,建立了压辊的力学模型;在此基础上,以某型对辊制粒机为初始模型,通过有限元软件Abaqus探究了压辊表面应力分布情况,并进一步对其长径比及支撑方式进行了优化,结果表明:压辊长径比为1.034时,最大应力比初始模型减小了8.92%,单侧支撑改为双侧支撑可使最大应力减小65.31%,因此这两种优化方式对提高压辊的使用寿命具有重要参考价值。

反向铜挤压机模具智能修整方法

针对目前反向铜挤压机实现修模自动化的难点是修模装置无法自适应不同的模具,提出了一种自适应智能修模系统。该系统由模具旋转定位装置和自适应修模器组成,模具经旋转定位后,自适应修模器的磨刷在电机带动下旋转并伸入模孔进行打磨,没有模孔位置的磨刷杆在模具端面被弹回,从而实现对不同模孔数模具的自适应修整。同时,为更好的自动化、智能化模具修整,基于机器人自学习修模工艺及机器人示教技术,构建自适应修模器的数字化平台,机器人通过读取主机录入数据或利用视觉识别技术获取模具数据,根据机身姿态、夹具更换/夹持状态、模具状态等,设定工艺及算法进行修模,实现对不同规格模具修整的自适应。该系统已成功应用于2台设备上判别挤压筒和模具的清理及润滑效果,实施效果良好。

大腔体六面顶金刚石压机铰链梁锻造模具结构多参数优化

针对大腔体六面顶金刚石压机关键部件铰链梁的锻造过程进行了研究。为提高铰链梁锻造模具的使用寿命,利用Deform-3D软件对终锻过程进行了模拟,并对模具结构参数进行了优化。首先以模具应力为优化目标,选取模具边角及圆角处的7个结构参数为设计变量。通过Plackett-Burman Design筛选出对模具应力影响较显著的变量,将其作为最终优化变量进行研究。利用Box-Behnken Design抽样并建立了响应面回归模型,在拟合模型有效的前提下,通过引入动态惯性权重及学习因子改进粒子群算法,利用其寻优得到最优模具结构参数,并通过有限元仿真验证了结果的可靠性。结果表明,通过对模具结构的多参数优化,模具应力减少了25%,模具使用寿命得到显著提高。

65MN钛电极块成型压制压力机成套装备设计与开发

提出了研发钛电极块成型压制压力机成套装备的必要性,确定并详细阐述了65MN钛电极块成型压制压力机成套装备的设计方案。介绍了钛电极块成型压制压力机成套装备,包括电极块成型压力机,附带辅助脱模推料功能的模具,旋转摆臂上料装置,转笼翻转装置以及码料集料台。整套装备的上料、压制、脱模、下料、码垛集料均由机械自动化实现,具有高效、低成本、节能等特点。

俄罗斯KB8046-4000型热模锻压力机维修保养

介绍了俄罗斯KB8046-4000型热模锻压力机曲轴、传动轴及其相关零部件的检修方法。其中曲轴及传动轴是其传动系统中最主要的两个部件,其维护保养状况直接影响压力机的使用寿命。