外文翻譯--一種采用現(xiàn)代先進控制算法的3軸臺式數(shù)控系統(tǒng)銑床（英文）

1、INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 1, pp. 39-47 FEBRUARY 2010 / 3910.1007/s12541-010-0005-4 1. Introduction As new fields such as IT(Information Technology), BT(Bio Techno

2、logy) and NT(Nano Technology) emerge as a driving force in the industry, the interests in micro-factory system have been growing. The micro-factory is a miniaturized flexible manu-facturing system which consumes minimal

3、space and energy compared to the conventional one, and it is desired to produce micro/meso size mechanical components necessary for IT, BT and NT applications. Major technical units contributing to micro mechanical ma-ch

4、ining systems are, to name a few, high speed spindle systems, micro high precision feeding systems, control systems to generate coordinated motions, tooling and chucking systems, frame design and module allocation scheme

5、s based upon optimization for high stiffness. Researchers have been trying to put micro technologies together to build micro-factory systems which make micro/meso size precision parts to meet the needs from the manufactu

6、ring industry.1 In this paper, we present a miniaturized 3-axis milling machine and a dedicated CNC system for the machine. The 3-axis milling machine is constructed as one of micro-factory module and designed to produce

7、 high precision micro parts. It has a desktop size of 200×300×200 mm3 and is serving as our testbed machine. From finite element analysis and an impact hammer test, we have verified that it has a good structura

8、l stiffness and high natural frequencies. A high speed air turbine spindle on the horizontal z-axis can run at up to 160,000 rpm. This 3-axis milling machine was put under real machining tests and it successfully demonst

9、rated its machining capabilities. A CNC system was developed for operation of the 3-axis desktop milling machine. The CNC system includes a G-code interpreter which can process a basic set of G-codes and M-codes in real

10、-time. The CNC system consists of two parts. The one is a Development of a 3-axis Desktop Milling Machine and a CNC System Using Advanced Modern Control AlgorithmsByung-Sub Kim1,#, Seung-Kook Ro1 and Jong-Kweon Park11N

11、ano Convergence Manufacturing Systems Research Division, Korea Institute of Machinery & Materials, Daejeon, South Korea, 305-343# Corresponding Author / E-mail: bkim@kimm.re.kr, TEL: +82-42-868-7109, FAX: +82-42-868-

12、7180KEYWORDS: 3-axis milling machine, CNC system, H∞ control, Input shaper, Cross-coupled controlIn this paper, we introduce a desktop-size 3-axis milling machine and a CNC system which was developed to operate the 3-ax

13、is milling machine. The 3-axis milling machine has a mini-desktop size of 200×300×200 mm3 and its cutting volume is 20×20×20 mm3. The vertically installed XY stage is driven by voice-coil motors, and

14、 for the z- axis, a magnetically preloaded air bearing and a linear motor are used. The air spindle runs at up to 160,000 rpm. The gravity force is acting on the y-direction, so a weight balancer using an air bearing cy

15、linder is installed to cancel out the gravity force acting on the XY stage in the y-direction. The CNC system designed for the 3-axis milling machine consists of two parts. The one is a graphical user interface program

16、 which runs under Microsoft Windows and the other is a DSP program which is implemented on a DSP board with TI TMS320C6701 chips. A G-code interpreter is included in the CNC system which can interpret and interpolate a

17、 basic set of G-codes and M-codes in real-time. To improve the performance of servo control loop in the CNC system beyond the traditional PID-type control, several modern control algorithms have been tested including H

18、∞ control, input shaping control, disturbance observer and cross-coupled control on the 3-axis milling machine. Experimental results show the effectiveness and drawbacks of each control scheme when they are applied to

19、the 3-axis desktop milling machine. Manuscript received: February 2, 2009 / Accepted: September 24, 2009© KSPE and Springer 2010 INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING Vol. 11, No. 1 FEB

20、RUARY 2010 / 41to be low in stiffness due to its air bearing, locate at a range of 250~390 Hz. The natural frequency of the XY stage shows at about 400 and 710 Hz and, for the back frame, it is around 440 and 640 Hz. I

21、t seems that the designed miniaturized 3-axis milling machine has higher natural frequencies than conventional machine tools. 0 200 400 600 800 1000 0.00.51.01.52.02.53.0XY stage center impact (Z)Back frame senter impact

22、Back frame corner impactAmplitude [m/s2/N]Frequency [Hz]XY stage and back frame 0 200 400 600 800 1000 0.00.51.01.52.02.53.0vertical mode 385 HzY dir. - corner impactY dir. - center impactX dir. - corner impactAmplitude

23、[m/s2/N]Frequency [Hz]pitching mode 265 Hzyoing 345 Hzrolling 575 Hzz-axis stage (air bearing) Fig. 4 Frequency response functions from an impact hammer test Table 1 Natural frequencies from impact hammer test Mode Natu

24、ral frequency [Hz] XY stage 710 (z-direction) z-axis stage 265(pitch), 385(vertical), 575(roll) 3. A CNC System 3.1 Graphical User Interface Program A PC-based CNC system was developed for the 3-axis milling machine. T

25、he developed CNC system has two parts, a graphical user interface program in the PC part and a DSP program in the DSP part. The PC part runs on MS-Windows and processes user inputs. The DSP part receives thousands timer

26、interrupts per second and interprets commands in real-time for each axis of a machine and executes servo control loops. Two parts share a dual port RAM and communicate each other through it. Fig. 5 shows the graphical us

27、er interface of the developed CNC system and its brief explanations. One of the major features of the user interface program is a 3D plot window at the bottom right corner in Fig. 5. It displays the tool path described i

28、n G-codes when the user interface program reads in a G-code file. The current tool position also appears as a small red dot on the screen so that CNC users can easily identify where the machining process goes in the G-co

29、de file. Users can also use contouring function which merges line segments and arcs which are tangent, or nearly tangent, into a single smooth motion without stopping at each end-point. Contouring can be turned on and of

30、f manually while a program is running, or it can be turned on and off by the program itself using M-codes M21 and M22. Currently implemented G-codes and M-codes are G00 (Rapid Motion), G01 (Linear Motion), G02 (CW Circul

31、ar Arc), G03 (CCW Circular Arc), G04 (Dwell), G17 (X-Y Plane Selection), G18 (Z-X Plane Selection), G19 (Y-Z Plane Selection), M21 (Contouring On), M22 (Contouring Off), M30 (Program End & Reset). Fig. 5 Graphical us

32、er interface of the developed CNC When a user click the Open G-code button, a whole G-code file is read in and saved in a memory area, and then the G-codes appear at the bottom left list box. When the Start G-code button

33、 is clicked, the user interface program takes out a line from the memory and checks its syntax and identifies all the meaningful tokens. During preprocessing a G-code line, the user interface program is supposed to compu

34、te, a motion plane, a driving axis, maximum allowable velocity and acceleration, the starting position of the deceleration, directional cosines. If the G-code line is about circular motion, the center point of the arc, t

35、he normal direction of the arc, and start and end angles are also computed by the user interface program. All the preprocessed information is entered in the DPRAM and handed to the DSP program. A circular buffer in the D

36、PRAM has rooms for only 4 lines of G-codes, so the user interface program needs to keep monitoring the circular buffer usage. When the user interface program finds that the DSP program finishes carrying out a G-code line

37、 and empties its space, it fills in the empty space in the circular buffer with a new preprocessed G-code line in the order in which they occur. 3.2 DSP Program The DSP program interpolates the preprocessed G-codes in re

38、al-time and generates position commands for multiple axes to follow. It also closes servo control loops. Generally a sampling rate is set to be ten times larger than the bandwidth of a plant to be controlled. The develop