哈工大数控大作业完美版

第一作业 调研报告11.1调研内容11.2工作量与要求11.3正文1The development and application of NC machine tool servo system2第二作业：典型曲线数字积分法插补方法132.1目的132.2要求13 2.3 DDA法双曲线插补的积分表达式13 2.4终点判别15 2.5插补举例15第三作业：加工中心零件加工编程173.1目的和要求173.2数控机床设备173.3加工工艺制订193.4要完成的程序编写任务22数控技术课程（2015）大作业院 （系）专 业 姓 名学 号班 号 任课教师完成日期 哈尔滨工业大学机电工程学院2015年5月数控大作业第一作业 调研报告1.1调研内容请以课堂所学习的知识为基础，自主选择课程中所涉及的任一知识点进行调研。可以调研知识点的发展脉络，也可以重点介绍该知识点的发展现状、争议与未来发展趋势。请提交交独一无二的报告1.2工作量与要求1. 报告需用英文撰写，可计算机打印，也可手写，但最后封面需手工签名。2. 格式请参照本科生毕业论文要求（见教务处网站），总字数不少于2000字。3.在调研报告的最后，请列出参考的主要文献（英文学术刊物上正式发表的文献不少于5篇）或网址，并在正文中标注引用。4. 如果出现雷同，两位同学均无成绩。1.3正文The development and application of NC machine tool servo systemSince the invention of NC machine tool in 1950s, servo system has been the indispensable component of the NC machine tool. With the rapid development of new materials, electronic power and controlling system, the servo system has evolved from the step-by-step system to DC system and then to AC system. As the blossom of AC servo technology, AC servo system will replace the DC system wholly and take up the dominant position in the family of servo system. With the electronic power conversion unit as actuator and controller as core , Servo system which contains the servo driver and servo motor constitutes the main part of the electric-driving and automatic control system . When working, firstly the servo system will receive the signal from NC devices, and then drive the motion of machine tool as well as ensure the accuracy and speediness of movement under the guidance of pulse command . Usually, precision and speed of the NC machine tool and other technical indicators mainly depend on the servo system itself1. The improvement and assortment of NC servo systemAt present, engineers tend to assess the quality by reference to several important indicators, such as precision, speed and so on. Therefore, a NC servo system must meet these requirements.High precisionUnlike the traditional manufacturing which can be manually handled to regulate and compensate errors, the NC servo system has a high demand on positioning accuracy and repeated positioning accuracyQuick repose characteristicQuick response is one of important indicators of servo systems dynamic quality which requires the servo system following the command signal with minimum error as well as quick repose and high stability. Once receiving the instruction of manipulator, the working machine can restore the original state of equilibrium quickly after a short regulation or a disturbance from outer space.Wide speed rangeDue to the difference in work piece materials, cutting tool and process requirements, servo system must have wide speed range, so as to ensure that the CNC machine in any circumstances can get the optimal cutting condition. Thus the machine tool can satisfy the requirement of high speed machining as well as the requirement of low speed feed.The speed range is generally larger than 1 to 10000. when the machine is working in a low cutting speed which ask for a larger stable torque output, NC servo system must maintain a good reliability.Good reliabilitythe usage of machine tool is frequent, usually with 24 hours continuous work, so the servo system must have good working reliability.Servo system of NC machine tool can be divided into open loop control system and closed loop control system according to the presence of feedback test components. Drive control Unit transforms feeding instructions to perform signal needed by actuator, and then actuator convert this signal into mechanical displacement.In Open loop control system, there is no feedback detecting components and comparing control links. On the contrary, these are essential part of a closed-loop control system.The composition of servo systemServo system can be classified into the feed drive system and the spindle drive system on the basis of function and usage. Besides,the NC servo system can also be sorted into open loop control system and the closed loop control system in light of the presence of feedback detecting element.In addition, according to the difference of actuators, servo system can be divided into stepping servo system, dc servo system and ac servo system.Stepping servo systemBefore the 1960 s,the stepping servo system is based on step motor driven hydraulic servo motor or characterized by power stepping motor as direct drive,and servo system uses open-loop control.Stepping servo system works with the pulse signal, and its speed and turning Angle depends on the frequency or the number of Instruction pulses.Because there is no testing and feedback loop, the precision of the stepper motor step depends on the step angle, the accuracy of the gear transmission clearance and so on, its accuracy is low. stepping motor is easy to appear vibration phenomenon when working in the low frequency,and its output torque decreases with increment of speed. Because the stepping servo system is the open loop control, step motor in the start of machine with the over-high frequency or large load showslost or blocked phenomenon and prone to appear phenomenon of high speed overshoot in the braking of the machine tool. At the same time, step motor speed accelerating from 0 to working speed requires longer time and slower speed response. But because of its simple structure, easy adjustment, and good working reliability and the low prices, the stepping system is a good choice in many many occasions of low occasions.Dc servo systemAfter 60 and 70 s, most of numerical control system adopts dc servo system. Dc servo motor has a good wide range speed performance, large output torque, and strong overload capacity. servo system also has evolved from open loop control into closed-loop control, thus in the industry as well as its related fields gains the more extensive or aboard application. However, with the rapid development of modern industry, the corresponding equivalents such as precision CNC machine tools, industrial robots make higher and higher requirements to the electrical servo system, especially the precision, reliability and otherperformance.The traditional dc motor uses a mechanical commutator, faced up with many problems in the application process, such as brush and commutator wear easily, maintenance work is heavy and the cost of it is high. Commutator reversing would produce sparks, the maximum speed of the motor and the application environment is limited;Dc motor has a more complex structure, higher cost,and prone to interfere other deviceswork.Ac servo systemThe existence of these problems, limiting the dc servo system in high precision, high performance requires the application of servo drive occasion.Because hard-overcoming weakness of dc motor, people have been seeking the development of ac servo motor to replace the dc motor whose advantage is limited by mechanical commutor and brush to satisfy the needs of various application fields, especially in the field of high precision and high-performance servo drive .But because the ac motor has strong coupling, nonlinear characteristics, so control is very complete and the high-performance application has been limited. Since the 1980 s, with the boom of the new technology such as electronic electricity, the modern control theory, and the breakthrough in the field of vector control algorithm, the original problems of AC motor which has bothered so many engineers has been solved, and ac servo development faster and faster.The characteristics of the ac servo systemIn addition to good stability, good rapidity,and high precision,servo motor system has a series of other advantages.with out the limitation of commutator circumferential speed and armature reactance potential numerical element, the speed limit ofAC motor can be design higher than DC motor in the same given motor. with a wide range of speed regulation, the most ac servo motor speed ratio can reach 1:50000,and high-performance servo motor speed ratio can even amount to ver 100000. Meet the numerical control machine tool drive, wide speed range and small static rate request. good torque speed characteristic AC motor as the constant torque output, i.e. within its rated speed output rated torque, in for a constant power output above the rated speed.And torque overload capacity, can overcome the inertia moment of inertia load moment at start-up.Meet the machine tool servo system, large output torque, good dynamic accordingly, high positioning accuracy demands.The research status of domestic ac servoAc servo system consists of the ac servo system based on asynchronous motor and the ac servo system on the base of synchronous motor.At present machine mainly adopts a permanent magnet synchronous ac servo system.In the field of ac servo research, the Japan, the United States and Europe are in the forefront.In the mid 1980s, Japan yaskawa company has successfully developed the worlds first ac servo drive.Then FANUC, Mitsubishi, Panasonic and other companies have launched their own ac servo system. Most of these products from aboard companies are based on the asynchronous motor. However,domestic institutes has set up late in ac servo system with asynchronous motor,and so far there are still no products available. Many domestic researchers put much importance on the research of permanent magnet synchronous motor servo system. Huazhong university of science and technology, Beijing machine tool research institute, xi an micro motor research institute, shenyang institute of automation of Chinese academy of sciences, lanzhou electric factory etc have started out in the research of AC servo system and are expected to launch their own products. DA98 all-digital ac servo drive unit from guangzhou NC manufacturing company has already knock at the door of high-precision servo driver industry in our country, broken the monopoly of foreign countries , and initiated a new era belonging to our national brands.Ac servo signal and numerical control system interface have three different modes, which can also divided into three stages.Domestically, Guangzhou CNC DA98 which belongs to the first generation and is also a epoch-making servo drive, at the same time, it is first all-digital domestic ac servo drive unit, pulse command it accept direction. The second generation is EDB series delegated by Aston, it can not only accept pulse command signal, but also receive the signal from the speed control and torque control analog input.The third generation is networked ac servo system.Networked servo system is the organic combination of industrial field-bus technology and full digital ac servo,which enables users to adjust the parameters according to load conditions and saves some unstable factors such as drift produced by analog circuits. Based on field bus network control technology,the servo system the microprocessor and field bus interface in all type ac motor servo drive, form independent of intelligent digital servo control unit, it directly connected to the industrial field bus, it formed a new type of network control system based on field-bus.Reduced the number of hardware and the attachment, the structure of intelligent units on independent, to the outside world and realize data sharing between each other, but also can use other field control equipment, easy to extend.So far, the network communication server product in domestic has not yet mature.Robotics institute of Beijing university of aeronautics and astronautics development design a network based on DSP + FPGA + ASIPM ac servo control system, the principle prototype has been got preliminary validation of the three-dimensional carving machine.currently, the most server drive adopt high-speed DSP processors,which promote the movement of all kinds of advanced control algorithms in the use of new type of drive. Mostly, suppliers of servo system employ the structure of DSP + CPLD (FPGA) on the hardware. Because the DSP and CPLD (FPGA) can repeat programming,they are easy to realize modular re-configurable of the ac servo system.As long as the software for corresponding different system configurations, including the control algorithm can control and asynchronous motor, permanent magnet synchronous servo motor, brush-less dc motor, and through the reconfiguration of FPGA can also drive dc motor and three phase induction of stepping motor.Its for NC machine tool upgrade and innovation has left a lot of space.The development tendency of ac servoWith the constant improvement of productive forces, the ac servo system will be sophisticated in the direction of the integration, intelligent and network .integration By using a single and multi-function control unit, the servo system can achieve position control and speed control function through the setting of software and constitute a half closed loop feedback unit configuration or full closed loop control system of high accuracy through the external interface elligentServer intelligent control mode, such as internal programming can achieve a certain trajectory in advance and control the surrounding IO port as well as the adjustment of master-slaves following with electronic CAM, workServer implementation is distributed by network.The servers modulation could be reconstructed with low cost .conclusionThe modern NC machine tool is developing rapidly in the direction of high speed and high precision.As the essential component of the NC machine tool,servo system has gradually equated to ac servo system which has several incomparable advantages compared with other servo systems. With the progress of the ac servo technology, it will gradually replace dc servo system overall.参考文献1Tryling, David P.Simpleservouses.ProQuest Journal,2009.2J. Cao；Z.W. Li；Z.X. Meng.Development Of ANcServoSystemBased On Fuzzy Adaptive Control.Key engineering materials,2009.3Fusaomi&Nagata.Development of CAM system based on industrial robotic servo controller without using robot languag.Robotics and Computer Integrated Manufacturing,2013.4Mulan WangKaiyun XuChuan HeLei Zhou.Research on Servo System for CNC Machine Tool Driven by Permanent Magnet Synchronous Torque Motor.Materials Engineering and Automatic Control,20125Xu, KaiyunLi, NingLin, JianHe, Chuan.Development of linear servo control system for CNC machine tool based on DSP.International Conference on Mechatronic Science, Electric Engineering and Computer,2011第二作业：典型曲线数字积分法插补方法2.1目的数字积分插补方法是实现数控插补功能的重要方法之一。除平面直线和圆弧外，数字积分法法也可以实现多坐标插补联动以及描绘如二次曲线甚至高次曲线等各种函数曲线，精度也能满足要求，在一些专用数控机床和高档数控系统中得到了广泛的应用。因此，深入理解数字积分插补方法是掌握数控加工知识的重要内容之一。2.2要求试参照直线和圆弧DDA插补方法，推导如下任一曲线的DDA法插补公式，要求有完整的推导过程，画出插补器的结构框图，讨论终点判别方法，并给出一个插补过程实例。1） 抛物线插补 2） 椭圆插补 3） 螺旋线插补 导程为P，螺旋升角4）其他线型2.3 DDA法双曲线插补的积分表达式对于双曲线对时间t求导,得到 由此可以导出，第一象限逆椭圆弧在两个方向上的速度分量 试中K为一常数。上试说明速度分量是随着动点变化的，令动点变化的，令动点的坐标，则可得DDA插补双曲线弧插补积分表达式 显然用DDA法进行椭圆弧插补时，是对切削点即时坐标与的数值分别进行累加，若累加器产生溢出，则在相应坐标方向进给一步。2.4插补器结构框图根据椭圆DDA插补积分表达式可知其插补方法如下：每产生一个控制脉冲，X、Y积分器迭代累加一次，溢出时相应坐标轴进给一次，Y积分器的溢出还要对X被积函数寄存器进行修正，X积分器的溢出还要对Y被积函数寄存器进行修正。画出插补器结构框图如图所示图 3-1 双曲线插补器结构框图JVX、JVY分别为X、Y被积函数寄存器JRX、JRY分别为X、Y积分累加器为插补控制脉冲，分别为X、Y轴溢出脉冲2.4终点判别分别判断XY坐标轴进给步数，当XY坐标均到达终点时插补结束。2.5插补举例插补第一象限双曲线，起点为(6,0)，终点为(10,8)，插补脉冲计算过程如表3-1所示，插补轨迹如图3-2所示。两坐标进给步数分别为4和8，一旦某坐标进给步数达到要求则停止该坐标方向的插补运算。表 3-1 插补运算过程运算次序X积分器X终Y积分器Y终JVX(yi)JRX(yi) XJVY(xi)JRY(xi)Y0000000000 1010011000000100010000000001010011001100100020000000001010011011000100030000000001010011000101011140001000101010011010000011150001001001010011011100011060001001101010011001001010070010010101000011010100010080010011101000011000001010090011101001000011001100010010001111010100001101100001001100110000110000110001010100120100010001000011110010010013010010000100001110000101001401011101010000111011100100150101001011000011111100010016010101110100010000110100111701101101010001000111000011180110001111000100001101001119011110100100010011111000112001110001110001001100010011图 3-1 双曲线插补轨迹第三作业：加工中心零件加工编程3.1目的和要求本作业通过给定一台数控机床具体技术参数和零件加工工艺卡，使学生对数控机床具体参数、加工能力和加工工艺流程有直观了解和认识。同时，锻炼学生解决实际加工问题的能力。1了解加工中心的具体技术参数，加工范围和加工能力；2了解实际加工中，从零件图纸分析到制定零件加工工艺过程； 3按照加工工艺编写指定的工序的零件数控加工程序。 3.2数控机床设备 （1）机床结构 主要由床身、铣头、横进给、升降台、冷却、润滑及电气等部分组成。XKJ325-1数控铣床配用GSK928型数控系统，对主轴和工作台纵横向进行控制，用户按照加工零件的尺寸及工艺要求，先编成零件的加工程控，最后完成各种几何形状的加工。（2）机床的用途和加工特点 本机床适用于多品种中、小批量生产的零件，对各种复杂曲线的凸轮、孔、样板弧形糟等零件的加工效能尤为显著；该机床高速性能好，工作稳定可靠，定位精度和重复精度较高，不需要模具就能确保零件的加工精度，减少辅助时间，提高劳动生产率。（3）加工中心的主要技术参数 数控机床的技术参数，反映了机床的性能及加工范围。表1 TH5640D立式加工中心的主要技术参数名称参数工作台工作台尺寸mm 400550T型槽mm 18H8允许负载kg 600 主轴主轴锥孔No BT40主轴直径mm 85 主周转速(标准型/高速型)rpm 22.5-2250/45-4500 主轴电机kw 5.5/7.5 行程移动范围mm 1000500470主轴端面至工作台面距离mm