【作者】 李茂月；

【导师】 富宏亚；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2012， 博士

【摘要】 机床的智能化是提高机床加工效率、降低加工成本、确保工件加工精度以及改善工件表面加工质量的有效途径之一，已经得到国际上许多国家的重视和研究。当前，数控系统所采用的是一种专用的封闭式体系结构，其以固定参数形式设定加工过程变量，在整个制造过程中CNC只是一个封闭式的开环执行机构。随着现代制造业向信息化、敏捷制造模式的发展，越来越暴露出其固有的缺陷，而应用在线监督、控制机床的状态可以提高切削效率和加工的安全性。为此，本文对智能型模块化开放式数控系统的实现技术以及数控铣削参数的在线智能控制技术进行了深入的研究。研究开发了基于OMAC标准的开放式智能型铣削数控系统平台，该平台能实现插补控制和外部切削参数的实时采集及控制。对构建智能数控系统的相关技术做了研究和介绍，包括硬件设备和软件支持技术。智能控制器软件系统设计为七个功能模块，包括：人机交互模块、任务生成模块、任务协调模块、自适应控制模块、离散逻辑控制模块、轴组模块和轴运动模块。研究规划了各个功能模块的任务和模块间的逻辑关系，同时研究了外部加工参数的在线实时采集及系统实现方案，方案要求采集过程具有“硬实时”特性，即能保证参数采集的准确、定时，更要保证模块间的任务协调、可控制，还能为在线过程参数的智能控制预留编程接口。研究了基于SERCOS通讯模式时驱动器技术参数在线实时反馈至控制器的实现方案，技术参数主要包括机床的进给速度和主轴转速。智能数控系统平台和相关技术的研究为过程参数的在线智能控制奠定了基础。铣削力是铣削过程中重要的物理参数之一，它不仅决定了铣削过程中所消耗的功率，而且还直接影响铣削热的产生，而铣削热影响铣削温度，铣削温度易加速刀具的磨损或破损，最终影响刀具的使用寿命。为此，本文以提高粗铣削的加工效率为前提，研究且实现了基于铣削力约束的在线过程参数自适应智能控制的相关技术。在构建机床适应控制仿真模型的基础上，对铣削适应控制进行了仿真研究。首先，利用实验样本对设计的基于BP神经网络的切削系统环节进行了训练，研究并编写了自调整因子的模糊控制器函数，通过仿真实验验证了控制器和控制算法的正确性。其次，为了在开放数控系统中实现基于切削力约束的在线变进给速度控制，利用有限状态机技术对控制器进行了行为建模，设计使用改变进给速度倍率来改变加工过程进给速度的方法，并提出使用“双共享内存”技术实现插补加工和智能过程控制的同步与协调。最后，对台阶形铝合金工件进行了加工实验，验证了实现开放式智能数控系统在线变速切削技术的正确性和优越性。由于断续铣削力的循环变化、铣刀几何条件决定的瞬时切削厚度的变化，都会增大切削振动，引起切削质量不稳定。而切削过程的动态特性和机床—刀具—工件系统的模态特性之间的相互作用会导致颤振。颤振不仅限制了金属切削过程中的效率，还降低了工件的表面质量，增加了刀具磨损的速率，造成了加工噪声。因此，金属切削过程中避免和抑制颤振非常重要。为此，本文研究了变主轴转速在线抑制颤振的相关技术。首先，研究了颤振领域常用的传感器监控技术，尤其是三向切削力和振动加速度传感器的各向分量在颤振监控过程中的时域和频域敏感信号特征。其次，针对监控信号的频域特性，研究了快速傅立叶变换技术及在颤振过程中对信号有效信息的提取技术。研究了变主轴转速抑制颤振的算法，并建立了颤振频率与主轴转速间的关系模型，为实现颤振抑制提供了理论基础。最后，研究了在开放式数控系统中实现变主轴转速在线抑制颤振的相关技术，提出了基于位置模式和可重构设计的速度模式两种控制方案，并研究了其在控制器模块间的数据实现流程。对连续变切削深度铝合金工件进行了在线颤振抑制加工实验，实验验证了开放式智能铣削数控系统在线抑制颤振技术的有效性。目前，含有复杂曲面的产品和零件在现代制造业中所占的比例越来越大，同时对加工的精度和效率的要求也越来越高。为此，本文对自适应NURBS插补技术进行了研究。分析并开发了基于限定弓高误差的自适应NURBS插补算法，并对具有梯形、S型加减速的自适应NURBS插补算法进行了研究和仿真加工。研究了自适应NURBS插补的S型加减速的简化算法。针对基于限定弓高误差的自适应NURBS插补算法在曲率半径波动处易出现加速度和加加速度突变且易超出允许值的情况，提出了一种基于曲率变化特性的柔性加减速的自适应NURBS插补方法，并将插补过程分为加速、基于曲率的自适应调整、最后制动三个阶段。将提出的基于曲率变化特性的自适应NURBS插补算法集成至开发的智能数控系统控制器中，并通过加工实验验证了其正确性。更多还原

【Abstract】 The intelligence of machine is one of an effective way in improving machiningefficiency, reducing processing cost, ensuring work-pieces’ machining accuracy andimproving the surface processing quality, and it has been accounted and studied inmany countries. At present, a kind of enclosed structure for numerical controlsystem is used, which sets process variables with fixed parameters form. Therefore,CNC is only an enclosed and open-loop actuator in the manufacturing. With thedevelopment of information, agile manufacturing mode in modern manufacturing,more and more inherent defects have been imposed. It can improve cuttingefficiency and manufacturing safety by using on-line supervision and controllingthe state of the machine. So some technologies have been deeply researched forrealization of an intelligent modular open architecture CNC system and cuttingparameters’ on-line intelligent control in milling.An open architecture intelligent milling CNC platform has been studied anddeveloped based on open modular architecture controller, which can realizeinterpolation control and external parameters’ real-time acquisition and control.Related technologies about realizing intelligent CNC system have been studied andintroduced, including hardware equipment and software supporting technologies.The software composition is divided into seven modules, including human machineinterface module, task generator module, task coordinate module, adaptive controlmodule, discrete logic control module, axis group module and axis module. At thesame time, the task for each module and logic relationships among modules havebeen planned. A scheme about external parameters’ on-line real-time acquisition andrealization of the CNC system have been studied and developed. There are severaldemands in this scheme, including the character of hard real-time in the process ofacquisition, which needs to acquire accurately and timely, to assure the tasks’coordinate and be controllable. On the other hand, it should reserve theprogramming interface for process parameters’ intelligent control. Theimplementation scheme has been studied how to feedback the actuator parameters tothe controller based on the SERCOS communication mode, and the parametersinclude the machine’s feed-rate and spindle speed. It plays an important role tostudy the intelligent CNC system platform and relative technologies for processparameters’ on-line intelligent control.Milling force is one of the most important physical parameters in the millingprocess, and it not only decides consumption power, but also directly affects the milling heat which affects the milling temperature. It is easy to cause tool’s wearand broken for high milling temperature. Finally it will affect the tool’s working life.For these reasons, relative technologies are studied about on-line processparameters’ adaptive intelligent control based on the constraint of milling force toimprove the milling efficiency in this thesis. Milling adaptive control has beenstudied in simulation on the basis of constructing machine tool’s adaptivesimulation model. At first, cutting system link based on designed BP network istrained with experimental samples. Then fuzzy controller function of automaticadjustment factor is studied and wrote. Finally the correctness of the controller andthe control algorithm are verified with simulation experiment. Secondly, to realizeon-line variable feed-rate control based on the constraint of cutting force in the openarchitecture CNC system, behavior model for the controller is established with thetechnology of finite state machine. The method of changing feed-rate override tochange the feed-rate is designed, and dual shared memory technology is raised torealize synchronization and coordination between interpolation and intelligentprocess control. At last, experiments verify the technologies of on-line variablefeed-rate to be correct and superior in the open architecture CNC system, which aredone with the step aluminum alloy work-piece.It will increase the cutting vibration and cause cutting quality unstable becauseof the cyclic changes of intermittent milling force and instantaneous cuttingthickness decided by tool’s geometry condition. On the other hand, it will formchatter due to the interaction between dynamic characters in the cutting process andmodal characteristics among machine, tool and work-piece. Chatter not only limitsthe cutting efficiency, but also reduces the quality of the work-piece surface,increases the tools’ wear rate, causes the process noise. So it is very important toavoid and suppress chatter during the metal cutting process. So relative on-linecontrol technologies about variable spindle speed suppress chatter have beenstudied in detailed in this thesis. Common sensor monitoring technologies areinvestigated in the field of chatter monitor. The time domain and frequency domainsensitive signal are studied including each component in three-component cuttingforce and acceleration sensors. Aimed at the control signal frequency characteristics,techniques including fast Fourier transform and the extraction of effectiveinformation are studied during chatter. The algorithm to suppress chatter by varyingspindle speed has been studied, and the relationship model is also set up betweenchatter frequency and spindle speed. All these provide the theoretical foundation torealize chatter suppression. Finally, Relative technologies are studied to suppresschatter by varying spindle speed in the CNC controller, and two control schemes are put forward including position mode and reconfigurable speed mode. At the sametime, the realization flowcharts are also studied about two schemes in the controllermodules. On-line chatter suppression experiments have been completed withcontinuous variable cutting depth aluminum alloy work-piece, and the experimentsverify the technologies’ correctness about on-line chatter suppression in the openarchitecture intelligent milling controller.At present, products and parts with complex curved surface are holding moreand more share in the modern manufacturing industry, and the demands ofmachining accuracy and efficiency are also becoming higher and higher. AdaptiveNURBS interpolation technologies have been studied in this thesis. AdaptiveNURBS interpolation algorithm based on chord error limited is analyzed anddeveloped, and the algorithm with trapezoid and S shape acceleration anddeceleration are studied and machined in simulation. A kind of simplified algorithmabout S shape acceleration and deceleration has been studied in the adaptiveNURBS interpolation. Because traditional algorithm is easy to break and beyond thelimited values in acceleration and jerk, an adaptive NURBS interpolation algorithmwith flexible acceleration and deceleration is presented which is based on thecharacteristics of the curvature. And this algorithm is divided into three phases,including acceleration, adaptive adjustment according to the curvature, braking inthe last. The algorithm presented is integrated into the developed controller ofintelligent CNC system, and it also has been verified its correctness with severalexperiments.更多还原