哈工大数控大作业完美版

第一作业调研报告 (1)

1.1调研内容 (1)

1.2工作量与要求 (1)

1.3正文 (1)

The development and application of NC machine tool servo system (2)

第二作业：典型曲线数字积分法插补方法 (13)

2.1目的 (13)

2.2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 (17)

3.1目的和要求 (17)

3.2数控机床设备 (17)

3.3加工工艺制订 (19)

3.4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 system Since 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 c ore , Servo system which contains the servo driver and servo motor const itutes 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 t he NC machine tool and other technical indicators

mainly depend on the servo system itself

1.The improvement and assortment of NC servo system

At present, engineers tend to assess the quality by reference to several im portant indicators, such as precision, speed and so on. Therefore, a NC se rvo system must meet these requirements.

High precision

Unlike the traditional manufacturing which can be manually handled to r egulate and compensate errors, the NC servo system has a high demand o n positioning accuracy and repeated positioning accuracy

Quick repose characteristic

Quick response is one of important indicators of servo system’s 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 range

Due 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 reliability

the 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 system

Servo 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 system

Before 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 shows"lost" 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 system

After 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 other performance.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 devices'work.

Ac servo system

The 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 system

In 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 of

AC 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 servo

Ac 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 world's first ac servo drive.Then F ANUC, 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 https://www.360docs.net/doc/7f15587680.html,worked 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.It's for NC machine tool upgrade and innovation has left a lot of space.

The development tendency of ac servo

With 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 composition.

intelligent

Server 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-slave's following with electronic CAM, etc.

network

Server implementation is distributed by network.The server's modulation could be reconstructed with low cost .

conclusion

The 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]

[1]Tryling, David P.Simple servo uses.ProQuest Journal,2009.

[2]J. Cao ；Z.W. Li ；Z.X. Meng.Development Of A Nc Servo System Based On Fuzzy Adaptive Control.Key engineering materials,2009.

[3]Fusaomi&Nagata.Development of CAM system based on industrial robotic servo controller without using robot languag.Robotics and

Computer Integrated Manufacturing,2013.

[4]Mulan Wang Kaiyun Xu Chuan He Lei Zhou.Research on Servo System for CNC Machine Tool Driven by Permanent Magnet Synchronous Torque Motor.Materials Engineering and Automatic Control,2012

[5]Xu, Kaiyun Li, Ning Lin, Jian He, 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 px y 22= 2）椭圆插补 C b y a x =+22

22

3）螺旋线插补 导程为P ，螺旋升角R P πλ2arctan =

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c b

y a x =-22

22 对时间t 求导,得到

02222=dt dy b y dt dx a x — X

b Y V V y x 22a = 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

??

???==y 2Ka x V x 2Kb y V

试中K 为一常数。上试说明速度分量y x V V ,是随着动点变化的，令动点变化的，令动点的坐标()i i y x ,，N

K t 2/1,1==? 则可得DDA 插补双曲线弧插补积分表达式