基于压电液压的快速刀具伺服系统研究

研究基于压电陶瓷(PZT)的新型快速刀具伺服系统,与液压放大方案耦合.这种设计的优势是轴向放大,降低了对阿贝误差的敏感性,紧凑的放大器设计和高带宽行程比.然后利用模型和数据对系统的性能进行了验证,表明系统满足了设计要求.     

数控刀具预调仪的误差修正

分析了力变形对刀具预调仪测量精度的影响,推导出非刚体模型下误差补偿公式,并对修正效果进行了验证。     

光学自由曲面快速刀具伺服车削误差的补偿

受各种误差因素以及周期性变化的切削力的影响,快速刀具伺服金刚石车削技术往往难以用一次车削获得满足光学性能要求的自由曲面。本文提出了一种利用线性差动传感器(LVDT)实现高精度接触式自由曲面在位测量的方法。该方法结合两自由度快速刀具伺服系统,实现了基于快速刀具伺服(FTS)的自由曲面车削加工的误差补偿。试验结果表明,该技术将自由曲面的加工精度提高了20%,表面粗糙度降低18.1%,解决了FTS系统与机床运动的同步问题,可补偿机床xyz三向运动误差,可用于自由曲面加工误差的修正。该方法还可用于不对称幅度较大的曲面或硬脆性材料的加工等,故促进了高精度光学自由曲面的推广应用。     

Maxwell电磁力驱动快速刀具伺服系统轨迹跟踪控制

Maxwell电磁力驱动避免了压电驱动器行程小和音圈电动机驱动力不足的固有缺点,在快速刀具伺服(fast tool servo,FTS)系统中极具应用前景.针对Maxwell电磁力驱动FTS系统的高性能轨迹跟踪问题,提出以阻尼控制改善被控对象基本动力学特性,再基于频域整形方法优化设计高增益PID控制器,实现FTS的高带...     

基于重复控制的快速刀具伺服系统前馈补偿方法

快速刀具伺服(Fast tool servo,FTS)系统的跟踪性能直接影响其对光学微结构表面的加工精度和加工效率。为此提出基于重复控制的离线前馈补偿方法,该方法通过对跟踪误差进行分段在线学习和离线补偿,实现FTS系统对非周期参考轨迹的高速精密跟踪。在自制单轴FTS系统上进行对比跟踪测试,测试结果表明：相比于二自由度控制方法,提出的离线前馈补偿方法对随机均匀B样条曲线和复合频率正弦曲线的均方根跟踪误差分别减小94.47%和93.83%。此外,将该FTS系统与超精密车床联动在高转速下加工得到网格面和复眼透镜阵列,这两种表面的最大轮廓误差分别为93.59 nm和134.73 nm,表面粗糙度均小于5 nm。研究结果为基于FTS的光学微结构表面高效、高精加工提供了新方法和新思路。     

数控铣削加工中刀具变形误差分析

通过分析计算数控铣削过程中刀具变形引起的误差,提出对这种误差的补偿方法。试验表明,该方法可显著提高数控加工效率与加工质量。计算结果可作为数控编程时力学仿形的基础。     

修正量角器示值误差加工角度样板

我校实习工厂由于条件限制,缺少精密角度量具,学生生产实习加工角度工件的精密角度样板,只能用普通万能量角器测量工件内外角度,常因量角器示值不准,角度超差,达不到图纸要求。 在实习教学过程中我们摸索出利用三角形内角和     

直齿插齿刀齿形造形误差及齿形角的合理修正方法

直齿插齿刀齿形造形误差及齿形角的合理修正方法重庆工具厂（６３００５５）周惠久用直齿插齿刀加工齿轮时，插齿刀就相当于一个齿形角（分圆上的齿形压力角）为ａ０的直齿轮与相同齿形角的直齿轮进行啮合。但由于插齿刀作有前后角，同时考虑到插齿刀本身制造的方便，齿侧...     

用更少的刀具进行快速加工

能高速精确运动的加工中心能用更少的刀具加工工件。显而易见，利用高速加工中心加工有许多孔的工件可以节省加工时间，降低生产成本。简单地说，我们的机床还可以运行得更快。工件的加工性能可能会限制它被加工的速度。但是如果机床的往复运动和刀具更换的速度更快的话，工件的加工周期还是可以缩短的。用这种方式可以节省很多加工时间。     

孔系中心距加工误差的修正方法

针对高精度孔系零件加工复杂的问题,提出了加工、修正工艺方法,给出了修正孔的坐标尺寸计算公式,并对公式进行了详细推导。实例验证表明该方法适用于加工高精度复杂孔系零件,具有广泛的应用价值与推广价值。     

快速刀具伺服分数阶PID控制仿真的研究

利用分数阶PID控制,提出了一种新的快速刀具伺服(FTS)跟踪控制方法,以改善FTS的控制性能。根据差分进化算法,讨论了分数阶PID控制器的参数整定;通过数值仿真,考察了该方法的可行性和有效性。针对FTS的轨迹跟踪,根据响应时间、跟踪精度等指标,详细比较了分数阶PID控制与传统PID控制的性能。仿真结果表明,分数阶PID控制器的阶跃响应时间约为5×10-7s,是PID控制响应时间的42%,对频率为1 kHz,幅值为1μm的正弦信号的跟踪误差约为6 nm,是PID跟踪误差的50%,验证了基于分数阶PID控制器实现FTS轨迹跟踪控制的可行性和优越性。     

Theoretical and experimental analysis of the effect of error motions on surface generation in fast tool servo machining

The fast tool servo (FTS) machining process provides an indispensable solution for machining optical microstructures with sub-micrometer form accuracy and a nanometric surface finish without the need for any subsequent post processing. The error motions in the FTS machining play an important role in the material removal process and surface generation. However, these issues have received relatively little attention. This paper presents a theoretical and experimental analysis of the effect of error motions on surface generation in FTS machining. This is accomplished by the establishment of a model-based simulation system for FTS machining, which is composed of a surface generation model, a tool path generator, and an error model. The major components of the error model include the stroke error of the FTS, the error motion of the machine slide in the feed direction, and the axial motion error of the main spindle. The form error due to the stroke error can be extracted empirically by regional analysis, the slide motion error and the axial motion error of the spindle are obtained by a kinematic model and the analysis of the profile in the circumferential direction in single point diamond turning (SPDT) of a flat surface, respectively. After incorporating the error model in the surface generation model, the model-based simulation system is capable of predicting the surface generation in FTS machining. A series of cutting tests were conducted. The predicted results were compared with the measured results, and hence the performance of the model-based simulation system was verified. The proposed research is helpful for the analysis and diagnosis of motion errors on the surface generation in the FTS machining process, and throws some light on the corresponding compensation and optimization solutions to improve the machining quality.     

压电陶瓷驱动的长行程快刀伺服机构设计

压电陶瓷驱动的快刀伺服技术是加工光学自由曲面等复杂曲面的有效方法。为了突破压电陶瓷驱动快刀伺服机构的行程局限,本文采用二级杠杆放大机构,设计了一种压电陶瓷驱动的长行程快刀伺服机构,实现了快刀伺服机构的长行程输出性能并消除了机构的寄生位移。基于伪刚体模型和拉格朗日原理对机构进行了动力学建模,综合行程和固有频率性能优化了机构参数并进行了有限元仿真和实验验证。机构等效刚度和固有频率的理论模型和有限元仿真结果误差分别为6.4%和1.6%,验证了理论模型的有效性。实验结果进一步表明,所设计的快刀伺服机构可实现100μm的输出行程同时具有730 Hz的固有频率,验证了所设计机构用于快刀伺服加工的有效性。系统的闭环跟踪实验也验证了系统良好的跟踪性能。     

Application of a fast tool servo for diamond turning of nonrotationally symmetric surfaces

The fabrication of nonrotationally symmetric surfaces by diamond turning requires tool actuation at a bandwidth significantly higher than the rotational frequency of the surfaces. This requirement cannot be met by standard slide drives due to their large mass and consequent low natural frequency. This articles describes the development of a laboratory-scale diamond-turning machine with piezoelectric-driven fast tool servo. The capability of this apparatus will be demonstrated for high-speed features such as sine wave, square wave, and ramp-shaped surfaces. Also described is the implementation of this fast tool servo on a commercial diamond-turning machine. Several nonrotationally symmetric surfaces have been machined, and their images are included.     

Characterization of surface defects in fast tool servo machining of microlens array using a pattern recognition and analysis method

Microlens array (MLA) is a type of structured freeform surfaces which are widely used in advanced optical products. Fast tool servo (FTS) machining provides an indispensible solution for machining MLA with superior surface quality than traditional fabrication process for MLA. However, there are a lot of challenges in the characterization of the surface defects in FTS machining of MLA. This paper presents a pattern recognition and analysis method (PRAM) for the characterization of surface defects in FTS machining of MLA. The PRAM makes use of the Gabor filters to extract the features from the MLA. These features are used to train a Support Vector Machine (SVM) classifier for defects detection and analysis. To verify the method, a series of experiments have been conducted and the results show that the PRAM produces good accuracy of defects detection using different features and different classifiers. The successful development of PRAM throws some light on further study of surface characterization of other types of structure freeform surfaces.     

Modeling and machining evaluation of microstructure fabrication by fast tool servo-based diamond machining

A fast-tool servo-machining process is typically utilized to generate sinusoidal microstructures for optical components only when the clearance angle of the cutting tool is greater than the critical value. This paper focuses on the generation characteristics of microstructures for surface texturing applications when the clearance angle of the cutting tool is smaller than this critical angle. A method for calculating the microstructure profile amplitude and wavelength is introduced for the prediction of microstructure generation. Cutting tests were conducted, and the measured results were quite close to the corresponding calculated results, further verifying the capability of the proposed analytical model.     

A novel surface analytical model for cutting linearization error in fast tool/slow slide servo diamond turning

Fast tool/slow slide servo (FTS/SSS) technology plays an important role in machining freeform surfaces for the modern optics industry. The surface accuracy is a sticking factor that demands the need for a long-standing solution to fabricate ultraprecise freeform surfaces accurately and efficiently. However, the analysis of cutting linearization errors in the cutting direction of surface generation has received little attention. Hence, a novel surface analytical model is developed to evaluate the cutting linearization error of all cutting strategies for surface generation. It also optimizes the number of cutting points to meet accuracy requirements. To validate the theoretical cutting linearization errors, a series of machining experiments on sinusoidal wave grid and micro-lens array surfaces has been conducted. The experimental results demonstrate that these surfaces have successfully achieved the surface accuracy requirement of 1 μm with the implementation of the proposed model. These further credit the capability of the surface analytical model as an effective and accurate tool in improving profile accuracies and meeting accuracy requirements.     

Design of a rotary fast tool servo for ophthalmic lens fabrication

We have developed a novel fast tool servo and associated prototype diamond- turning machine for the production of plastic spectacle lenses. Our fast tool servo carries the cutting tool on a rotary arm and, thus, on a circular path, as opposed to straight line paths in conventional designs. The actuator, sensors, and bearings are standard elements that together allow experimentally demonstrated 500 m/s² instantaneous accelerations at the tool tip over a 3-cm range of cutting depth. We also describe in this paper new approaches we have developed for toolpath generation and calibration. The paper also presents associated control algorithms, because the controller must supply very high dynamic stiffness to the tool servo axis at multiples of the spindle frequency. This stiffness is achieved by means of repetitive control techniques. The new fast tool servo is shown to have great promise for machining asymmetric surfaces with large amplitude asymmetries.     

Development of a piezoelectrically actuated two-degree-of-freedom fast tool servo with decoupled motions for micro-/nanomachining

The limited degrees of freedom (DOFs) of servo motions is an inherent deficiency in conventional, fast-tool-servo-(FTS)-assisted, diamond-turning, highly blocking applications of the FTS technique. In this paper, the concept of two-DOF FTS (2-DOF FTS)-assisted diamond turning is proposed and demonstrated. A piezoelectrically actuated 2-DOF FTS mechanism is developed to enable the cutting tool to move along two directions with decoupled motions. A novel guidance flexural mechanism constructed using the newly proposed Z-shaped flexure hinges (ZFHs) is introduced to generate motions along the z-axis, which is based on the bending deformation of the beams of the ZFHs. Additionally, using the differential moving principle (DMP), bi-directional motions in the x-axis direction can be achieved. Using the matrix-based compliance modeling method, the kinematics of the mechanism are analytically described, and the dynamics are also modeled using the Lagrangian principle. The theoretical results are then verified using finite element analysis (FEA). Certain increases in performances over conventional two-DOF flexural mechanisms are achieved: (a) a more compact structure with lower moving inertia, (b) theoretically decoupled motions of the output end, and (c) less than one actuator per DOF. To investigate the practical performance of the 2-DOF FTS system, both open-loop and closed-loop tests are conducted. Finally, the developed 2-DOF FTS technique is implemented to realize an innovative Pseudo-Random Diamond Turning (PRDT) method for the fabrication of micro-structured surfaces with scattering homogenization. The cutting results demonstrate not only the superiority of the concept but also the efficiency of the developed 2-DOF FTS system.     

航天器元件多参数综合可靠性环境试验研究综述

综述了航天器元件综合可靠性环境试验研究的背景、意义及国内外研究现状,提出了高线加速度、振动、温度、气压、噪声五参数的综合环境试验样机的研究步骤和技术方案,针对方案实现的几个关键技术问题——离心机动平衡问题、振动台动圈的纠偏问题、离心机机臂的抑振问题、离心加速度场作用下的温度场及声场控制问题进行了简要分析并提出拟解决的办法。