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...     

凸轮范成加工的刀具误差补偿分析

通过分析凸轮范成加工中影响凸轮机构运动精度的有关因素,提出了一种能对刀具误差进行有效补偿的工艺方法。     

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...     

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。     

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。     

成形车刀加工锥体工件产生的双曲线误差的修正

用普通成形车刀加工锥体工件要产生双曲线误差。实践证明,双曲线误差往往使加工后的工件超差。目前虽有几种减小双曲线误差的方法,但不理想,因各种方法对圆体成形车刀自身造成双曲线误差都不能减小,而自身造成误差一般占整个双曲线误差的95％。有必要寻求一种新的方法减小这种误差。双曲线误差产生的原因是因为用带有前角的普通成形车刀加工锥体时,前刀面与锥体表面的交线是一条外凸的双曲线,要加工     

快速伺服刀架迟滞特性的Preisach建模

使用压电陶瓷作驱动元部件的快速伺服刀架是一种新的加工手段。本文介绍了基于Preisach模型的快速伺服刀架迟滞特性建模方法。作为快速伺服刀架的驱动元部件,压电陶瓷微位移器自身的迟滞、蠕变等非线性特性严重影响了快速伺服刀架的动态性能。为了精确建立快速伺服刀架的迟滞模型,给出了Preisach模型的数字表达方式,通过一系列实验测得的数据证明快速伺服刀架系统具有一致特性与擦除特性,满足Preisach模型的两个必要条件,最后在实验数据的基础上建立了基于Preisach模型的迟滞特性模型。实验表明,该迟滞模型可以很好地预测快速伺服刀架的迟滞位移曲线,其预测误差不超过0.65 μm。     

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。     

静电陀螺仪对准误差产生的系统伺服随动误差分析

介绍了采用平行光管式光电位置探测器(PSD)测角的静电陀螺仪在伺服测试转台上测试时,陀螺坐标系与平台台体坐标系之间的两种对准误差,然后推导出由该对准误差引起的反射光斑中心点在PSD平面坐标系上的坐标变化公式,给出了当陀螺坐标系与台体坐标系之间存在对准误差时,计算伺服随动误差的步骤,并根据静电陀螺仪的结构及工作情况,选取一组数据进行了计算。结果表明:第一种对准误差比第二种对准误差约大两个数量级;为减小系统伺服随动误差,第一种对准误差应不大于4'。其结论对静电陀螺仪的设计与测试具有理论指导意义。     

高频高精快刀伺服系统优化

研制了一款高频响、高精度及大驱动力的压电驱动型快速刀具伺服(Fast Tool Servo,FTS)装置,采用广义圆锥线拟合的柔性铰链构造新颖的柔性机构,通过对称布置的结构消除柔性刀架工作过程中在非期望运动方向的耦合误差,并对机构的运动学特性进行了综合建模.综合考虑装置行程和固有频率的设计目标,基于改进的BP神经网络优...     

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.