电化学机械复合加工实时压紧力控制的研究

分析了压紧力变化的原因以及对电化学机械复合加工的影响,在此基础上以Windows98为开发平台,以Delphi、VC、VTOOLSD为开发语言,以工控PC机作为控制系统的核心,开发了基于脉冲电化学机械复合加工的实时压紧力控制系统,使电化学作用和机械作用达到良好的匹配,从而有效地提高了加工效率和表面质量。     

机器人柔性抛光机床的力控制系统的建模与辨识

机器人柔性抛光系统中,力控制系统是重要的组成部分.力控制系统对抛光加工性能有重要的影响,直接关系着抛光质量.该力控制系统实际上是一个闭环的交流伺服系统,对力控制系统的建模为抛光系统的动态和静态性能分析提供了理论基础.     

Composite adaptive control of belt polishing force for aero-engine blade

The existing methods for blade polishing mainly focus on robot polishing and manual grinding.Due to the difficulty in high-precision control of the polishing force,the blade surface precision is very low in robot polishing,in particular,quality of the inlet and exhaust edges can not satisfy the processing requirements.Manual grinding has low efficiency,high labor intensity and unstable processing quality,moreover,the polished surface is vulnerable to burn,and the surface precision and integrity are difficult to ensure.In order to further improve the profile accuracy and surface quality,a pneumatic flexible polishing force-exerting mechanism is designed and a dual-mode switching composite adaptive control(DSCAC) strategy is proposed,which combines Bang-Bang control and model reference adaptive control based on fuzzy neural network(MRACFNN) together.By the mode decision-making mechanism,Bang-Bang control is used to track the control command signal quickly when the actual polishing force is far away from the target value,and MRACFNN is utilized in smaller error ranges to improve the system robustness and control precision.Based on the mathematical model of the force-exerting mechanism,simulation analysis is implemented on DSCAC.Simulation results show that the output polishing force can better track the given signal.Finally,the blade polishing experiments are carried out on the designed polishing equipment.Experimental results show that DSCAC can effectively mitigate the influence of gas compressibility,valve dead-time effect,valve nonlinear flow,cylinder friction,measurement noise and other interference on the control precision of polishing force,which has high control precision,strong robustness,strong anti-interference ability and other advantages compared with MRACFNN.The proposed research achieves high-precision control of the polishing force,effectively improves the blade machining precision and surface consistency,and significantly reduces the surface roughness.     

非球面精密数控研抛中研抛力的控制

提出了一种基于磁流变力矩伺服装置(MRT)的研抛力控制方法来控制非球面数控研抛系统中的研抛力以实现恒压力研抛.研究了该方法的原理、模型、影响因素并研发了相应的实验研究系统.阐述了基于磁流变力矩伺服装置的研抛力控制原理;应用Preston方程分析了恒压力控制的重要性并基于Hertz理论建立了研抛压力模型,进而建立了研抛力...     

航空发动机叶片砂带抛光力控制技术

基于制造集成化对航空发动机叶片的抛光要求,针对叶片抛光过程中抛光力的非线性和时变性难以控制等问题,提出一种建立抛光力控制系统数学模型并进行模糊比例-积分-微分控制的方法。研制了砂带抛光施力和运动机构,以气缸和比例阀为主要研究对象,建立抛光力控制系统的数学模型,结合模糊比例-积分-微分控制原理,设计了自适应模糊比例-积分-微分控制器。对抛光力控制系统进行系统仿真与实验验证,结果表明,所采用的模糊比例-积分-微分控制系统具有快速响应性和较强的鲁棒性,可以满足叶片抛光过程中抛光力的控制要求。     

航空发动机叶片砂带抛光力的干扰观测补偿控制

为提高叶片尺寸精度及表面质量,针对气体的可压缩性、阀的死区效应、阀的流量非线性、气缸摩擦力和测量噪声等干扰因素对叶片抛光力控制精度的影响,提出了一种基于干扰观测器的反向传播神经网络比例—积分—微分控制方法.该方法通过构造干扰观测器来预测抛光力气动控制系统中的非线性干扰,并在控制中引入等效的补偿来抑制干扰,同时利用反向传播神经网络控制算法对比例—积分—微分控制参数进行在线自适应整定.仿真分析和实验结果表明,基于干扰观测器的反向传播神经网络比例—积分—微分控制器具有控制精度高、鲁棒性强、抑制干扰能力强等优点,能够提高叶片型面尺寸精度和表面一致性、降低表面粗糙度、减小残余应力并提高抛光效率.     

Simultaneous tool posture and polishing force control of unknown curved surface using serial-parallel mechanism polishing machine

In automotive manufacturing, the repair polishing process of an automotive body is still manually performed by skilled polishing workers. This is because skilled workers can appropriately control the polishing motion and force according to the workpiece conditions based on their experience. However, the number of skilled workers has been decreasing. Additionally, the skill development of younger workers has not been satisfactorily conducted. To overcome such problems, in a previous research investigation, we developed a serial-parallel mechanism polishing machine that effectively reproduced the polishing motion and force of skilled workers. This replication system, however, had limited use because the acquired polishing techniques could not adapt to various workpiece conditions, such as shape and size. The present study aimed to expand the polishing method for application to curved surfaces, in other words, adapt the replication system to changes in the workpiece shape. In the past polishing methods for curved surfaces, the workpiece shape was acquired by using CAD data or external sensors that often led to an increase in process time and cost. However, the newly proposed method in this study requires neither CAD data nor external sensors, and was able to effectively achieve simultaneous posture and force control on unknown curved surface. The experimental results showed that the skilled polishing techniques were successfully replicated on an unknown curved surface and the surface roughness was greatly improved by integrating the newly proposed method into the skilled polishing replication system.     

A knowledge-based system for sensor interaction and real-time component control

This paper outlines the integration of a two-dimensional vision system with a pneumatic proximity-to-tactile sensing device to form a Co-ordinated ‘Hand-Eye’ system. With the aid of a knowledge base this system is utilised as an intelligent condition monitoring tool for recognition and detection of orientation of parts in a flexible manufacturing environment. An expert system is formulated to interrogate the acquired data streams for the purpose of comparative studies with the knowledge base. Appropriate data processing methods are employed to ensure rapid manipulation of data for real-time applications.     

Dual-trap optical tweezers with real-time force clamp control

Single molecule force clamp experiments are widely used to investigate how enzymes, molecular motors, and other molecular mechanisms work. We developed a dual-trap optical tweezers instrument with real-time (200 kHz update rate) force clamp control that can exert 0-100 pN forces on trapped beads. A model for force clamp experiments in the dumbbell-geometry is presented. We observe good agreement between predicted and observed power spectra of bead position and force fluctuations. The model can be used to predict and optimize the dynamics of real-time force clamp optical tweezers instruments. The results from a proof-of-principle experiment in which lambda exonuclease converts a double-stranded DNA tether, held at constant tension, into its single-stranded form, show that the developed instrument is suitable for experiments in single molecule biology.     

基于接触力控制的抛光轮磨损在线补偿策略研究

提出了一种用于玻璃多面体磨削成形加工设备的抛光轮磨损在线补偿策略,由抛光接触力实时估算、抛光轮磨损预测算法和前馈-反馈混合方式接触力控制模块构成。该补偿策略无需采用精密测距传感器即可解决抛光轮长期运行磨损所导致的半径参数持续漂移。文中详细论述了抛光轮磨损在线补偿策略的原理和实现方式,并在实验室构建了玻璃多面体精密高效磨削加工原型机,对该补偿策略进行了应用测试。从加工样本采集的测试数据与理论分析呈现了良好的一致性,验证了所提出方法的正确性和有效性,及其在玻璃多面体磨削成形加工应用中的广泛应用前景。     

虚拟加工的磁流变抛光面形预测

为了精确高效地预测磁流变抛光面形误差,提出一种基于虚拟加工的预测算法。针对实际抛光的特点,建立磁流变抛光面形预测的理论模型,提出面形预测质量的评价方法,并结合工程实际阐述该算法的实现方法。通过修正去除函数、重定义驻留时间和优化Preston系数等方法,得到与实际加工一致性较好的预测结果。实验表明,该方法有较高的精度、计算效率和稳定性。     

Performance of laser polishing in finishing of metallic surfaces

Laser polishing is presently regarded as one of the enabling technologies hoped to eventually replace the need for time-consuming and error-prone manual polishing operations which are often required by metallic surfaces. During laser polishing, a thin layer of material is being melted as a result of laser irradiation. Since molten metal is characterized by increased relocation capabilities, laser polishing is generally accompanied by a more or less significant decrease in the surface roughness. The primary objective of this study is to present a comprehensive snapshot of the advancements made over more than one decade with respect to theoretical and experimental investigation of laser polishing technology. However, in addition to the usual review of the state-of-the-art in the field, the study places an increased emphasis on the finishing performance of the process, defined through the perspective of pre- and postpolishing surface roughness. The implementation of this metric with strong practical implications has revealed that under appropriate process parameters, certain classes of metallic materials can reduce their average surface roughness by more than 80 %, possibly to R _a ?=?5 nm. Nonetheless, a more rigorous and fundamental understanding of the intrinsic mechanisms underlying laser polishing remains one of the currently unfulfilled premises toward a wider industrial adoption of the process.     

超精密工作台控制方案的优化选择

采用直线电动机加气浮导轨模式搭建大行程纳米级分辨率的超精密工作台,并建立超精密工作台进给系统的数学模型.通过计算机仿真分别分析单位反馈PID控制、带加速度前馈的PID控制、位置速度双环反馈和Smith预估控制等控制模式在不同材料做导轨时的控制指标.在控制系统选择上采用层次分析法建立综合评价体系,通过分析、计算、比较,确定位置环、速度环的双环反馈控制为本工作台最佳控制方案.     

大口径光学抛光系统的气动压力控制

为提高大口径光学抛光设备的加工工艺,在具有行星式旋转结构的末端执行器的基础上,提出了一种高精度、高稳定性的气动压力控制系统,解决了整个系统设计中的气动关键技术问题.从整个系统的设计角度分析了执行装置的工作原理和整个气动部分不同参数对控制的影响,以指导压力控制系统的设计.利用压力传感器和比例阀及多组双模态PID控制算法构建了闭环压力控制系统,以实现高精度、高稳定性的抛光盘压力控制.实验结果表明,该气动压力控制系统可以满足大口径抛光系统对压力的设计要求.     

小型磁力研磨机床数控系统设计

磁力研磨作为一种新兴的表面光整技术,在细长管内壁研磨方面有着独特的优势,但目前市场上磁力研磨专用的数控机床设备较少。针对传统数控系统在小型机床上应用的缺陷,基于STM32+FreeRTOS实时操作系统设计了数控机床的嵌入式软硬件,建立了三层拓扑结构的软件系统。对主轴转速伺服控制进行了研究,通过系统辨识建立主轴数学模型,基于Ziegler-Nichols方法整定PID参数。以活检针为例进行了实际的磨削实验,试验结果表明,该机床磨削过程稳定、加工精度高。     

低压力铜化学机械抛光集散控制系统

针对化学机械抛光设备提出了PC+NC+实时网络分布式可编程自动控制器的控制方案,并介绍了该系统的总体结构和主控制系统、网络化协调控制子系统、分布式执行控制子系统等核心环节的软硬件实现技术.单区域抛光头气压控制结果表明,该系统具有较高的稳定性和可靠性,能很好地满足化学机械抛光项目的总体要求.     

Stewart平台力控制系统研发

采用位移控制模式或称住姿控制的六自由度Stewart平台已经得到了广泛的应用,采用力控制模式(这里称之为力姿force posture控制)的研究和应用却很少,其中控制技术困难、稳定性差是重要的原因.而采用力姿控制在柔性加工、交会对接、实验边界模拟等方面具有非常广泛的应用前景.该文介绍了在Stewart平台上进行的力控制系统开发,实现了力姿控制.     

A neural-Taguchi-based quasi time-optimization control strategy for chemical-mechanical polishing processes

Besides the major factors such as the down force, back pressure and the rotating speed of wafer carrier, effect of polishing time is also an important issue in CMP processes. In this study, a neural-Taguchi method based on a cost-effective quasi time-optimisation technique for chemical-mechanical polishing (CMP) processes is developed. The key concept of this new technique is that an optimal process parameter set is obtained through a neural-network-simulated CMP process model. Under such an optimal parameter set, the desired material removal rate within-wafer-nonuniformity can be reached with the optimal polishing time. It has been proved by experiment that the proposed method can offer a better polishing performance while reducing the polishing time by 1/3.     

A novel method for micro-gap control in electrogenerated chemical polishing

In the electrogenerated chemical polishing (EGCP), material removal rate (MRR) is inversely proportional to the processing gap. To polish a workpiece with a large area, high and uniform MRR is necessary, which prefers a small and uniform processing gap. Based on the principle of the hydrostatic support, a novel micro-gap control method is proposed. The method uniformly controls the gap between the electrode and workpiece to a micro level over a large area. A relationship between the gap size and the inlet pressure is derived theoretically and verified experimentally. The proposed method is successfully applied to the polishing of a Cu surface with a diameter of 50 mm. Promising results are obtained that surface roughness and flatness are reduced from average roughness (Ra) 82 nm and peak-to-valley (PV) value 290 nm to Ra 4 nm and PV 120 nm, respectively.