Prevention of galling in forming of deep hole with retreat and advance pulse ram motion on servo press

To prevent galling in backward extrusion of deep holes, an extrusion method utilizing a servo press and a punch having an internal channel for supplying liquid lubricant is proposed. On the servo press, the punch is pushed into the billet in a manner combining pulsed and stepwise modes. The lubricant is sucked into the formed hole through the internal channel during the retreat motion of the punch. Appropriate punch ram motions for preventing galling are determined from the surface observation of the formed hole. The maximum aspect ratio of the hole attained by the proposed method is discussed.     

Experimental and numerical analysis of friction in high aspect ratio combined forward-backward extrusion with retreat and advance pulse ram motion on a servo press

A method for maintaining lubrication in the backward extrusion of deep holes for lightweight structural components is proposed utilizing a servo press and a punch with an internal channel for liquid lubricant supply. In this forming method, the punch is pushed into the specimen with a servo press in a manner that combines pulsed and stepwise modes. Sufficient liquid lubricant is periodically supplied to the deformation zone through the internal channel upon the retreat of the punch. This forming method with pulse punch ram motion was tested in combined forward-backward extrusion process with a high aspect ratio (height/diameter) in this study. The material flow of the aluminum specimen during the extrusion with pulse punch ram motion was investigated to determine the coefficient of shear friction at the specimen–punch interface. The punch wear was assessed by a finite element analysis of the material flow of the specimen during the extrusion with pulse punch ram motion.     

Influence of the press ram motion on the joining characteristics during indentation plastic joining using a servo press

A plastic joining method for fixing bars and hot plates, called “indentation plastic joining”, was carried out using a servo press with press ram speed control. The influence of the press ram motion control on the indentation joining characteristics of an aluminum alloy bar and plate was examined. The accelerated ram motion was effective in reducing the bar indentation pressure by approximately 15% and the bonding strength of the indented bar–plate was improved by approximately 7%. The bonding mechanism underlying the indention joining method under press ram motion control is discussed in terms of the seizure of the plate and the mechanical clamping associated with the process. It is found that the accelerated ram motion produces heavier seizure at the indented bar–plate interface, whereas the decelerated ram motion reduces the degree of the seizure.     

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.     

基于伺服压力机的板料成形研究现状与发展趋势

伺服压力机作为新一代的成形设备在板料成形领域正日益发挥重要作用。本文介绍了伺服压力机的技术特点,并面向冲裁、弯曲、拉深等典型板料成形工艺综述了伺服压力机在降低生产成本、优化工艺和提高产品质量方面的研究进展。此外,针对伺服压力机可设置保压及滑块运动精确可控的优点,综述了其在高强钢热冲压等复杂热成形过程中的应用。最后,对伺服压力机在板料锻造成形工艺上的应用与发展进行了展望。     

伺服压力机位置/压力自动补偿精确运动控制研究

为了满足机械伺服压力机压力精确控制的需求,设计了一种位置/压力自动补偿精确控制的运动控制系统。首先,分析了发那科控制系统位置/压力控制原理;然后,在压力机上设计位置/压力自动补偿运动控制系统,系统通过回归校正算法提高了应变压力传感器的反馈精度,结合发那科伺服电机与控制器实现位置模式和压力模式的平稳切换;最终,实现伺服压力机位置和压力的精确自适应控制。对伺服压力机不同压力负载控制情况下压力反馈曲线和压力与位置的响应特性曲线进行分析,结果表明,本控制系统满足伺服压力机位置与压力控制的精度和稳定性的要求。     

一种用于深冲压系统的新型压力机构优化设计及运动仿真

提出了一种用于深冲压的新型压力机构,并对其可行性进行验证。首先,将新型压力机构等同为连杆机构,并且进行了阐述,通过测试其几何结构取得系统的运动尺寸,主要分析了压力系统的位移、速度及加速度的变化;然后,采取优化方法找出可变联轴器的运动尺寸,通过具体的实例,在Solid Edge三维软件中对压力系统构建实体模型;最后,将实体模型导入到ADAMS软件中进行运动仿真,并且与传统六连杆压力机构模型仿真结果进行了对比。研究结果表明,优化设计的冲头速度和加速度(曲柄大约位于90°~240°的角位置处)比传统六连杆压力机平稳,能很好实现深冲压的输出运动。     

Effects of forming conditions on homogeneity of microstructure and mechanical properties of A6061 aluminum alloy manufactured by time-dependent rheoforging on a mechanical servo press

The different forming behaviors of the solid and liquid phases in semisolid metal slurry during deformation result in products with inhomogeneous quality. A mechanical servo press with the capability of multistage compression was employed to forge A6061 aluminum alloy in the semisolid state. A time-dependent rheoforging strategy including mechanical stirring, a fast first compression, short holding, and a secondary compression was designed to improve the homogeneity of rheoforged samples. The distributions of the microstructure and mechanical properties, such as the solid fraction, hardness, and deformation resistance, of samples manufactured under various experimental conditions were investigated. When the stirred semisolid A6061 slurry was forged in the temperature range from 625 to 628 °C with a short holding time of 4 s and the upper die preheated to 300 °C, samples with a homogeneous microstructure and mechanical properties were manufactured. The homogeneity of rheoforged samples was attributed to the controllable free motion capability of the mechanical servo press and the adjustable fluidity and viscosity of the semisolid slurry.     

伺服压力机传动系统动态特性分析与研究

为了提高伺服压力机传动系统的动态特性,建立了曲柄肘杆传动系统的结构简图,运用矢量方程法建立了该机构的几何参数数学模型,然后根据等效转动惯量的转换条件建立了该系统的等效转动惯量数学方程,最后通过MATLAB软件建立了该系统的数学模型,分析得出该机构在主滑块不同行程长度时所对应的等效转动惯量幅值曲线,并分析了在伺服电机恒扭矩输出时曲柄的加减速性能。分析结果表明,通过减小该机构的主滑块行程长度,可以明显减小转动惯量,提高曲柄的角加速度,从而提高该系统的动态性能。     

多点成形中的柔性压边技术研究

对于薄板类零件而言,无论是利用整体模具成形还是多点成形,影响成形零件质量的关键因素是起皱。为了防止薄板类零件成形过程中产生起皱,尽量提高薄板类零件的变形量,研制了一种适合于多点成形的新型柔性压边装置,依据成形件的工艺特点、变形大小、材料特性及其弹性模量和成形零件形状,可以确定压边力的大小,且与板料直接接触的柔性压边圈随成形零件的形状不同而有所变形。介绍了多点成形压力机专用的柔性压边装置的工作原理、工作过程、布置结构、力学分析、成形力及压边力的计算。阐述了实际使用过程中的压边力和成形力的调节方法及柔性压边力,实现了数字无级调压,通过调节柔性压边力,明显改善了薄板类零件的成形质量。     

基于MATLAB的摆辗机摆头圆和直线成形轨迹仿真与分析

具有双偏心套结构的摆辗机摆头可以实现多种运动轨迹,其中圆和直线运动轨迹应用较多。为了直观显示及分析运动轨迹的摆辗成形过程,根据摆头运动原理,建立摆头运动方程,应用MATLAB软件,针对摆辗机摆头圆和直线运动轨迹,叠加坯料向上送进油缸的运动,进行摆头三维运动轨迹的仿真模拟及规律分析。摆头在圆运动轨迹运动时,摆辗成形过程曲线为螺旋线,摆头摆角不为0且固定,摆辗成形过程是连续的局部成形。摆头在直线运动轨迹下,摆辗成形过程曲线为之字形曲线,摆角大小变化频繁,当运动曲线通过中心点时,摆头摆角为0,工件成形由局部变为整体成形,所需成形力增大。     

多点压机成形与多道次多点模具成形的数值模拟研究

变形路径对于板材的成形质量有着重要的影响。多点压机成形和多道次多点模具成形充分利用多点成形的柔性特点,实现了对板材变形路径的控制。文章通过有限元数值模拟研究了这两种成形方式各自的特点和规律,并进行了比较。结果表明,多点压机成形和多道次多点模具成形,都能够优化板材变形路径,使变形均匀,有效地抑制起皱,提高板材变形能力。在同样条件下,多点压机方式好于多道次成形,但当多道次成形道次逐渐增多时,成形质量接近于多点压机成形。多点压机成形是理想化的成形方式,但设备造价昂贵,多道次多点模具成形可以近似实现多点压机成形效果。     

成形角对单点渐进成形精度影响的研究

成形精度是单点渐进成形面临的一个重要问题,其目前所能达到的成形精度为±3 mm,然而在工业生产中要求金属板料成形精度为±0.2 mm。因此,如何提高单点渐进成形的成形精度是一项重要的课题。首先通过实验方法得出回弹量随成形角变化的规律;其次,采用不同负补偿值的方法对不同成形角下的试件进行补偿,并得到相应条件下试件的回弹量;最后,找出回弹量随补偿值变化规律,并采用最小二乘法原理进行拟合得到关系式。研究结果说明,只要在加工之前根据补偿值大小预测出该成形角下的回弹量,就能判断出该试件是否符合要求。     

基于MATLAB的四连杆伺服压力机控制求解

针对伺服压力机相关控制参数进行求解研究,建立了四连杆式伺服压力机机械结构和同步电机二者联合的数学状态模型,在给定加工工艺轨迹曲线和负载转矩曲线的条件下,在MATLAB平台上进行数学运算求解,获得伺服电机的转速曲线和响应参数,包括d-q坐标系上的电枢电流和电枢电压。研究结果有助于根据实际工艺曲线快速制定伺服同步电机控制策略,对伺服同步电机控制提供计算参数,同时也可以从电机参数上进行优化,根据模型正向修改加工工艺轨迹,使工艺曲线控制在电机的驱动能力范围内。     

伺服压力机三角连杆式传动机构的仿真与优化

针对一种应用于伺服压力机的三角连杆式传动机构,用ADAMS软件,依据特定的拉深工艺要求设置目标函数,进行动态仿真和结构优化.得到优化后的三角连杆机构滑块的运动速度和输出压力的特性,在电机恒转速的情况下,比优化前三角连杆机构和直连杆机构更适合用于板材的拉深加工.该机构在伺服电机的变速率特性的驱动下,可以更充分满足拉深工艺的需求.     

炸药压制液压机的设计与结构探讨

本文基于炸药压制爆炸机理,列举了多种炸药压制液压机防爆结构及功能部件的典型设计,并对这些典型的结构型式进行了阐述及其优缺点分析。在总结炸药压制液压机结构设计的基础上,提出了进一步改进的方向和措施。     

SP-160伺服压力机传动系统设计分析

根据市场需求设计伺服压力机的传动系统,利用SolidWorks软件进行压力机传动系统三维建模,并进行强度和刚度分析,校核各主要零部件是否满足设计要求。     

Material characterization and finite element analysis of a pressboard under press forming

Pressboard is a wood-based material consisting of lignin, hemicellulose and high percentage of cellulose. It is used as primary sheet in the manufacturing process of cellulose ring. The pressboard used in this study is a viscoelastic material with mechanical properties depending on time, temperature and moisture content. Using finite element method and based on nonlinear viscoelastic model, the pressboard material behavior was simulated using WLF equation and the data were obtained from material tests. The simulation results conformed to the related experiments, indicating that the approach can accurately predict spring back, stress relaxation and strain recovery within a press forming process.     

Effects on the deep drawing diagram in micro forming

The limits of the processing window for deep drawing, collected in a deep drawing diagram, are affected by material behavior, process parameters and size effects. A size effect, more specific a density effect, explains the changes in forming behavior of foils with respect to the forming limit, denoted by the limiting drawing ratio. It is shown that it occurs in so called Tiffany structures. The changes in the tribology in deep drawing have an influence on the clamping limit of the processing window. The changes are induced by changes of the drawing speed. They can be explained by the lubricant pocket model only if one takes the temperature dependence of the viscosity of the lubricant into account.     

基于OPC协议的伺服压力机上位机控制软件的研究

主要研究了伺服压力机上位机控制软件的关键技术,着重考虑了软件针对不同类型规格伺服压力机的通用性,采用模块化软件体系,提出了一套柔性的OPC数据交互引擎,并将它应用于基于OPC协议的伺服压力机控制软件上,使得控制软件可以独立于特定的硬件平台,降低了软件的扩展维护难度,提高了软件的可移植性.