Phase-Division-Based Dynamic Optimization of Linkages for Drawing Servo Presses

Existing linkage-optimization methods are designed for mechanical presses; few can be directly used for servo presses, so development of the servo press is limited. Based on the complementarity of linkage opti- mization and motion planning, a phase-division-based linkage-optimization model for a drawing servo press is established. Considering the motion-planning principles of a drawing servo press, and taking account of work rating and efficiency, the constraints of the optimization model are constructed. Linkage is optimized in two modes： use of either constant eccentric speed or constant slide speed in the work segments. The performances of optimized link- ages are compared with those of a mature linkage SL4- 2000A, which is optimized by a traditional method. The results show that the work rating of a drawing servo press equipped with linkages optimized by this new method improved and the root-mean-square torque of the servo motors is reduced by more than 10%. This research pro- vides a promising method for designing energy-saving drawing servo presses with high work ratings.

Does friction contribute to formability improvement using servo press?

Servo press forming machines are advanced forming systems that are capable of imparting interrupted punch motion,resulting in enhanced room temperature formability.The exact mechanism of the formability improvement is not yet established.The contribution of interrupted motion in the ductility improvement has been studied through stress relaxation phenomena in uniaxial tensile(UT)tests.However,the reason for improved formability observed when employing servo press is complicated due to the additional contribution from frictional effects.In the present work,an attempt is made to decouple the friction effect on formability improvement numerically.The improved formability is studied using a hole expansion test(HET).The limit of forming during hole expansion is modeled using the Hosford–Coulomb(HC)damage criteria,which is implemented as a user subroutine in a commercial explicit finite element(FE)software.Only the contribution of stress relaxation is accounted for in the evolution of the damage variable during interrupted loading.Therefore,the difference between simulation and experimental hole expansion ratio(HER)can be used to decouple the friction effect from the overall formability improvement during hole expansion.The improvement in HER due to stress relaxation and friction effect is different.The study showed that the model effectively captures the hole expansion deformation process in both monotonic and interrupted loading conditions.Compared to stress relaxation,friction effect played a major role during interrupted HET.

Deep Drawing with Local Hardening on Digital Multi-axis Servo Press

The paper discusses a new drawing technology, based on a synchronized movement of ram and cushion with multiple bending operations in alternating directions called ＂bi-directional deep drawing（BDD）.＂ The goal is to avoid local thinning by strengthening the weak point using local hardening. BDD operations are realized before the conventional deep drawing process. This results in a local strain hardening at the weak point of the workpiece, which is usually located at the bottom punch radius. Two major aspects have to be given attention due to the high number of process parameters. On the one hand, for process design, it is helpful to have a tool by means of which it is possible to simultaneously create both the machine program for the servo press and the initial configuration for the process simulation. From the authors＇ point of view, this complexity can only be represented by a numerical analysis method, on the other hand. Consequently, both aspects are given attention in this paper.

Design of a Servo Mechanical Press with Redundant Actuation

A servo press is a new type of mechanical press that is driven by programmable motors and offers superior performance such as low noise, excellent efficiency and high precision for metal forming operations. Similar to multi-link mechanical presses, a servo mechanical press tends to grow in size as the tonnage increases that calls for larger, heavy duty servo motors, which could be expensive and may not even be available. In this paper, a new concept of servo mechanical press with redundant actuation is proposed firstly using two servo motors driving one input shaft, i.e. one-point-two-motor mode that makes it possible to produce a larger press with available servomotors. Then the punching mechanism design is detailed. The performance indices are set up including mechanical advantage reciprocal and link force ratios. A bounded feasible solution space is constructed for dimensional synthesis based on non-dimensional link lengths and assembly conditions. The performance atlases are depicted over the bounded feasible solution space that lead to a visual solution of the punching mechanism with global optimization. Finally, case studies are given to illustrate the design method with visual global optimization, and a prototype with 200 t punching force is being developed in our laboratory to demonstrate efficacy of the new concept for servo mechanical press. The presented research provides a feasible solution to the development of heavy-duty servo mechanical presses and finds potential applications in the development of other types of heavy equipments with electric drive.

Optimal Design of a Main Driving Mechanism for Servo Punch Press Based on Performance Atlases

The servomotor drive turret punch press is attracting more attentions and being developed more intensively due to the advantages of high speed,high accuracy,high flexibility,high productivity,low noise,cleaning and energy saving.To effectively improve the performance and lower the cost,it is necessary to develop new mechanisms and establish corresponding optimal design method with uniform performance indices.A new patented main driving mechanism and a new optimal design method are proposed.In the optimal design,the performance indices,i.e.,the local motion/force transmission indices ITI,OTI,good transmission workspace good transmission workspace(GTW) and the global transmission indices GTIs are defined.The non-dimensional normalization method is used to get all feasible solutions in dimensional synthesis.Thereafter,the performance atlases,which can present all possible design solutions,are depicted.As a result,the feasible solution of the mechanism with good motion/force transmission performance is obtained.And the solution can be flexibly adjusted by designer according to the practical design requirements.The proposed mechanism is original,and the presented design method provides a feasible solution to the optimal design of the main driving mechanism for servo punch press.

Study of Dynamic Robustness of Servo Control System on a Water Press

The reliability and robustness of the electro-hydraulic servo control system for heavy-duty forging machine play an important role in forging processes. A mathematic model of 50 MN water press for free forging was created in this research. The dynamic robust compensator integrating with PID control method is designed and applied to the mathematical model simulation. The simulated results approved that the dynamic robust compensator application restrains interference from extra load and improves the electro-hydraulic position servo control system accuracy and stability.

Fuzzy iterative learning control of electro-hydraulic servo system for SRM direct-drive volume control hydraulic press

A new kind of volume control hydraulic press that combines the advantages of both hydraulic and SRM(switched reluctance motor) driving technology is developed.Considering that the serious dead zone and time-variant nonlinearity exist in the volume control electro-hydraulic servo system,the ILC(iterative learning control) method is applied to tracking the displacement curve of the hydraulic press slider.In order to improve the convergence speed and precision of ILC,a fuzzy ILC algorithm that utilizes the fuzzy strategy to adaptively adjust the iterative learning gains is put forward.The simulation and experimental researches are carried out to investigate the convergence speed and precision of the fuzzy ILC for hydraulic press slider position tracking.The results show that the fuzzy ILC can raise the iterative learning speed enormously,and realize the tracking control of slider displacement curve with rapid response speed and high control precision.In experiment,the maximum tracking error 0.02 V is achieved through 12 iterations only.

数控压机伺服控制系统复合控制器I-ABC与PID优化

为了提高数控压机伺服控制系统的控制精度,针对伺服控制系统运行控制过程构建数学模型,在人工蜂群算法基础上融入了云分析模型,之后采用改进人工蜂群算法(Improved Artificial Bee Colony,I-ABC)调节比例-积分-微分(Proportional Integral Differential,PID)参数,建立了一种复合控制方法。研究结果表明:以I-ABC进行PID控制时,可以使幅度差降低到0.4%,相位差基本在-0.54°之内,系统加载精度也获得了明显提升,表现出了更优的跟踪性能。以I-ABC进行PID控制时,能够对多余力起到明显抑制作用,响应速度也获得明显提升,可以有效满足系统的准确控制要求。在系统内加入干扰信号,引入I-ABC实施PID调节可以减小系统超调量,还可以获得更短调节时间,使系统获得更强抗干扰性能。

基于指数趋近率的液压机泵控伺服系统滑模控制

滑模控制方法具备较强鲁棒性,控制器结构也较简单,被广泛应用于泵控电液伺服液压系统上。在分析泵控系统原理的基础上,为克服传统PID控制很难抵抗较强外部干扰力的缺点,泵控伺服系统建立指数趋近律滑模控制器,建立泵控伺服系统MATLAB/Simulink仿真。研究结果表明:正弦信号跟踪下,滑模控制最大稳态跟踪误差与PID相比降低83.4%,同时控制器IMSE指标相对PID控制器发生了显著降低。该研究有助于提高液压机运行效率,对提高产品质量具有一定的指导意义。

基于热冲压生产线的12000kN数字机械伺服压力机关键技术及应用

本文探讨了基于数字机械伺服压力机的热冲压生产线的研究及应用。随着汽车轻量化和安全性能要求的提高,高强钢热冲压成形车身零部件的广泛应用成为汽车制造业的发展趋势。热冲压成形技术由于其成形性能和复杂构型成形能力,成为满足高强度钢车身结构件要求的重要选择。然而,传统热冲压生产线在满足高强度钢件成形要求上仍存在一定挑战。新一代热冲压生产线基于数字机械伺服压力机,采用先进的热冲压成形技术和自动化输送系统,能够满足大型复杂高强钢车身零部件对高强钢材料进行热冲压加工的需求,提高生产效率和产品质量。

伺服压力机用飞轮电池蓄能系统参数计算方法探讨

飞轮电池作为伺服压力机的蓄能器的补充,可以回收伺服装备的制动能量,其主动控制输入输出功率的特性也可以保障设备运行总体功率消耗的平稳。本文针对飞轮电池应用于伺服压力机这一技术,对飞轮电池系统的参数的计算方法进行研究,为可控蓄能器在锻压装备上的应用提供技术积累。

一种多功能锻造液压机的控制系统与控制方法

近年锻造行业的快速发展,对锻件的要求越来越高,对锻造压机也提出了各种挑战,多功能锻造液压机应运而生,即在同一台液压机上实现铝合金、镁合金、钛合金和高温合金等制件的自由锻造、精密挤压锻造和等温锻造三种锻造工艺。本文主要对多功能液压机的控制系统与控制方法进行阐述。

四轴联动热挤压成形液压机及伺服控制系统的应用

结合公司为国内某航空研究院研发的一台高精度四轴联动热挤压成形设备,详细阐述了伺服运动控制系统在同步轴中的运用,巧妙利用高频响阀的特性曲线,实现了碳纤维等复合材料的热压成形。本文重点分析该热挤压成形液压机的液压原理及其电控系统的实现。

液压机双驱伺服系统滑模变结构控制研究

为了提高液压机双驱伺服系统的控制精度,设计了一种基于位置与速度传感器反馈的协同策略,并设计了滑模变结构模糊控制器。研究结果表明:在不同转速间速率转变时通过三角函数形式完成柔性的过渡过程,满足转速的设计条件。滑块在运行过程中可迅速完成合模与回程的运动。进行加载处理时则以低速状态运行,获得理想的加载精度。该研究有助于提高液压机的控制精度,为后续的参数设计奠定一定的理论基础。

基于改进复合三角函数的伺服压力机轨迹规划研究

为使伺服压力机具有良好的拉深性能,需要对其轨迹进行合理规划。针对六连杆大型伺服压力机,构建一种主传动机构轨迹规划方法。基于库伦-粘性摩擦模型,建立主传动机构的高精度动力学模型。考虑冲压过程中的工艺约束和要求,提出基于复合三角函数的伺服电机加减速控制的改进模型。针对主传动机构的能耗和效率进行分析,以滑块运动的周期能耗和生产节拍为优化指标,通过线性加权的方式构造多目标优化函数,引入机械手送料时间、滑块最大速度、主动件角速度、伺服电机动态限和热极限等约束,采用遗传算法完成了多目标优化设计。结果显示:优化后,伺服压力机主传动机构在一个周期的能效提升4.54%,生产节拍时间减小3.23%,实现了良好的拉深工艺模式。

基于改进FNN-CCC的双伺服压力机同步控制策略研究

目的改善双伺服压力机同步控制策略的动态响应性能和鲁棒性,提升双伺服压力机的单轴跟踪精度和双轴同步精度,实现成形过程的高精度位置控制。方法建立双伺服压力机驱动系统数学模型,分析系统同步误差来源,结合模糊神经网络单轴控制算法,引入迭代学习律,设计一种改进模糊神经网络-交叉耦合(FNN-CCC)同步控制器。基于系统控制模型进行单轴阶跃响应特性与双轴正弦跟随特性仿真,搭建嵌入式双伺服压力机驱动系统试验平台,在偏载干扰条件下进行双轴同步控制试验,验证所提出理论的有效性。结果仿真结果表明,与模糊控制算法和BP神经网络控制算法相比,该控制器单轴控制算法的超调量分别减少了11.5%和25.5%,调节时间分别减少了48.8%和34.4%,具有更好的动态响应性能。与原控制器相比,改进后的交叉耦合同步控制器最大双轴同步误差降低了65.7%,同步控制精度有所提高。试验结果表明,与传统PID-交叉耦合控制器相比,改进的FNN-CCC控制器有更好的控制性能,在热冲压合模成形阶段,单轴跟踪误差分别减小了81.8%和75.0%,双轴同步误差减小了69.2%。结论所提出的同步控制策略在偏载干扰条件下具有较好的动态响应性能和鲁棒性,能够使同步误差快速收敛,提高了双伺服压力机驱动系统的单轴跟踪精度和双轴同步控制精度,实现了对双伺服压力机的高精度控制。

交流伺服式机械压力机及其关键技术探讨

论述了制造业是中国的治国之本、兴国之器、强国之基,而先进的装备制造业是我国当前与未来重点的发展领域。分析了机器由机械本体系统与电气控制系统组成,而机械本体系统分别由动力源、传动部件和工作机构组成,明确指出直驱与近零传动是未来机器的发展方向。对比分析了交流异步电动机与交流永磁同步伺服电动机的优缺点,指出交流永磁同步伺服电动机是机械压力机的理想动力源。第三代锻压设备的交流伺服式机械压力机及其驱动与传动的三种典型方式分别为小型压机用丝杠-带轮式、中型压机用带轮-偏载丝杠-肘杆式、大中型压机则采用带轮-多级齿轮-曲柄滑块式。分析了国内外伺服压力机的产品现状,中大吨位的伺服压力机常采用多个交流伺服同步电动机共同驱动的方式。对交流伺服式机械压力机的关键技术进行了探讨,为我国伺服压力机追赶国际先进水平奠定坚实的基础。

伺服直驱螺旋压力机在难变形金属精密锻造中的应用

随着航空工业发展,航空难变形金属锻造领域的要求越来越高,锻件的要求向高性能、轻量化、精密近净成型方向发展。伺服直驱螺旋压力机具有零传动、低噪声、高精度、能量无级调节等特点,为航空难变形金属精密锻造提供优于传统的解决方案。

汽车门盖包边工艺研究及机械伺服包边机的研制

本文对比分析了现有汽车门盖包边工艺及特点,针对现有液压驱动的包边压力机生产效率低、能耗高、使用成本高等问题,开发了由伺服电机驱动的肘杆式包边压力机。该机主传动系统采用肘杆机构左右对称布置,通过ADAMS建立虚拟样机模型,进行肘杆机构角架杆长优化设计;优化后,肘杆机构具有更优的增力效果,在接近下止点时,滑块下线速度更平滑,更有利于包边成形。

双伺服油电混合折弯机液压及控制系统设计

本文针对折弯机制造技术的发展趋势,阐述了瑞铁机床油电混合系列折弯机的技术特点和优势。该系列设备采用公司独特的增速缸技术和双伺服泵控技术,使油缸高速下行时的速度得到了极大提升,提高折弯效率,同步性更好。配以瑞铁专用DH15P数控系统,成熟的泵控液压算法、简单便捷的人机界面、稳定的折弯精度、强大的图形编程功能使得机床综合性价比优势明显。其突出的性能也在实际生产中得到验证。