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1、目 录1 Spindle variable speed system design and analysis forCNC lathe experiment System12 数控车床实验系统的主轴变频调速系统设计分析6Spindle variable speed system design and analysis for CNC lathe experiment SystemZHENG Yan-qin，TANG Xue-zhe( School of Mechanical Engineering，Zhejiang University of Technology，Hangzhou 31001
2、4，China)Abstract: Mainly for the demand of designing high-accuracy，fast-response CNC lathe spindle variable speed system，a speed control proposal of fitting frequency motor and transducer together was raised via analyzing the basic principles and frequency of the variable frequency speed controlAcco
3、rding to the CNC lathe experimental system operating conditions，the lathe cutting force and spindle motor power were calculated，evidence for choosing spindle adjustable frequency motor of experiment system was provided In the light of the selected motor character，the basic principle of choosing tran
4、sducer was proposed，then a transducer was selected which matched the frequency motor in the rated capacity and rated current It is a high-performance and general-purpose voltage transducer using vector controlFinally，briefly the designideas for CNC lathe experimental platform were describedThe frequ
5、ency motor and transducer are reasonable，and its adjustable performance and starting torque can meet the requirements of the experimental systemKey words: variable frequency speed control; adjustable frequency motor; transducer; CNC lathe0 IntroductionWith the development of modern industrial techno
6、logy, frequency conversion and speed regulation technology in mechanical processing has been widely applied. In the CNC lathe spindle rotary precision of experimental system, determines the components the processing precision, frequency speed control of NC machine tool spindle speed, high efficiency
7、, wide range, high precision, the spindle speed is more and more using variable frequency speed regulation. From the spindle speed on the overall system performance indicators, how to select motor and inverter motor and inverter, achieve the best match, the spindle is the key to design of variable f
8、requency speed regulation system. This study focused on the experimental system of NC lathe spindle frequency control system design.1 the basic principle of frequency conversionAC induction motor speed is: N0 = n ( 1 - s ) = 60F ( 1 - s ) / P ( 1)Type : F - stator power supply frequency, s, slip, P
9、- magnetic pole logarithm. By the formula (1 ) knowledge, change the frequency of the power supply F, motor speed will be adjusted, this is the variable frequency speed regulation. Converter with power semiconductor device on-off action, could be the power supply conversion to another frequency step
10、less speed regulation of motor power, provide the required voltage, frequency, realizes the stepless speed regulation of asynchronous motor. Frequency converter to realize the conversion of the main mode of AC - AC variable frequency and AC - DC - AC frequency converter ( inverter direct torque cont
11、rol and vector control variable frequency ). AC - AC frequency conversion is to change the thyristor control angle of changing size and frequency, AC - AC voltage and frequency adjustment. Use the thyristor conduction performance, this study put the power to convert AC power to DC power, and then by
12、 the use of SCR inverter main circuit, output three-phase frequency and voltage can be adjusted, equivalent to a sinusoidal pulse width modulation wave ( SPWM wave ), AC - DC - AC variable frequency, drag the three-phase asynchronous motor speed operation ( 4-5 ).2 CNC lathe spindle speed control ex
13、periment system of variable frequency motor selectionDue to the complexity of cutting process, the cutting force influencing factor is very much, therefore has not yet been derived and easy to calculate cutting force FX, FY, FZ theoretical formula, generally through a large number of experiments, th
14、e establishment of the experience formula to calculate cutting force. This study will back cutting depth, feed rate and cutting speed of 3 main factors as variable factors, and other factors, correction coefficientIndirect calculation, it can be FX, FY, FZ 3 component ( 6 ) empirical formula:FZ = CF
15、zaxFzp fyFzVnFzFY = CFyaxFyp fyFyVnFyFX = CFxaxFxfyFxVnFz nFxp fyFxV nF ( 2) Type : FZ - FY - cutting force; radial force; FX - feeding force; V - cutting speed, V = nd / ( 1000 x 60 ); N - workpiece speed; D - F - feed the workpiece diameter. When turning, FZ than FY, FX is much greater, and FY, FX
16、 direction movement speed is small, therefore, FY, FX power consumption is very small (only 1% 2% ), it can be ignored. Used in lathe cutting force calculation formula is as follows: FZ = 9 81CFzaxFzP ( 3)According to the numerical control lathe experimental system operating conditions, to take: CFz
17、 = 40, xFz = 1, yFz = 0.75, apmax = 6 mm, Fmax = 0.2 mm / R, n = 2500 mm / min, d = 30 mm. The cutting power of Pm = Fz, V x 10 - 3 = 704.13 x 3.93 x 10 - 3 = 2.765 kW. The study of machine tool transmission efficiency for M = 0.75, then the NC machine tool spindle motor power PE Pm / M = 3.687 kW.F
18、ed by inverter asynchronous motor running condition produced fundamental change ( 7 ), when the motor runs, along with the frequency changer style pressure control, mechanical characteristic curve can be arbitrary translation, which enable asynchronous motor performance is improved greatly. Therefor
19、e, CNC Experiment System of variable frequency motor selection, also should be considered : the lathe spindle motor and power characteristics matching problem; the frequency conversion motor and motor frame size as far as possible the same strength; the cutting and processing of the heterogeneity of
20、 the material, the main motor power should have a certain reserve ( 8-9 ).Selection of experimental system of Xinxiang City special motor manufacturing company limited series of 4 YVP variable frequency motor rated power, rated torque of 5.5 kW, 30 N m, the rated current of 12 A, with similar freque
21、ncy conversion device matching, interchangeability, general strong, its power, foot mounting dimensions and center of Higher Correspondence index and Y series asynchronous motor is completely consistent, and experimental systemEntry requirements. The main technical indexes for the three-phase voltag
22、e: 380 V / 50 Hz; variable frequency speed regulation range: 5 Hz 100 Hz stepless speed regulation. The low speed torque smoothing, without creeping phenomenon; through the conversion device of voltage boosting, ensure the motor in 5 Hz rated output torque and the motor for heating and burning.3 inv
23、erter type selectionn the CNC lathe spindle speed control experimental system, inverter selection should pay attention to : 1 converter is to realize constant pressure control and constant current control; the inverter load performance curve; the frequency converter and load matching problem of the
24、rated voltage, current, frequency and load rated voltage, current match, for the special load needs to reference the motor performance parameters to determine the maximum current of inverter, current and overload capacity, in the constant torque or speed reducing device should also pay attention to
25、the torque matching; considering the harmonic causes the output current increases, the converter drive motor, especially the reactance small high-speed motor, the capacity should be slightly larger than the common motor selection; the cable, motor on the coupling capacitance exists, also can cause t
26、he increase of current, converter capacity should be increased properly; and adopts the PWM control inverter, rectifier controllable converter, power factor is relatively low, the harmonic pollution is serious, cannot realize energy recycling, in demanding situations, rectifying and inverting proces
27、s using PWM control of double PWM frequency converter ( 10 ).In the CNC lathe in the experiment system, selection of inverter, inverter current rating is a key quantity. The 4 pole above the motor or motor connected in parallel, must with total current does not exceed the rated current for the princ
28、iple of frequency converter. CNC machine tool belongs to continuous operation, continuous operation to control the rated capacity and rated current should satisfy the type:PCNkPMcos ( kVA)PCNk 3UMIM 10 3 ( kVA)ICNkIM( A) ( 4)Type : PM - load required motor power output shaft; the ETA, the efficiency
29、 of the motor ( usually about 0.85 ); Cos - motor power factor ( usually about 0.75 ); UM - motor voltage, V; IM: A; K motor current, current waveform correction coefficient ( PWM 1.05 1 ); PCN inverter rated capacity, kVA; ICN, the rated current of the inverter, A.Frequency converter and asynchrono
30、us motor is composed of different speed regulation system, the converter capacity calculation methods are also different. The above applies to single inverter for single motor supply and continuous operation, the three are unified, selection of frequency inverter capacity should meet 3 formula.In th
31、e CNC lathe spindle speed control system in the experimental system, frequency converter is selected in accordance with the motor models identified, motor rated current of IM for 12 A, rated voltage 380 V, rated at 5.5 kW, select the converter capacity and rated current should satisfy the type:PCNkP
32、Mcos = 1 05 5 50 85 0 75 = 9 0( kVA)PCNk 3UMIM 10 3 = 8 3( kVA)ICNkIM = 1 05 12 = 12 6( A) ( 5) On the dynamic performance requirements of high CNC experiment system, the original use of DC transmission. At present, vector control inverter has been universal, for the requirements of high precision,
33、fast response CNC experiment system, the use of vector control of high performance general-purpose inverter is a kind of very good plan ( 11 ), and, in small capacity inverter with voltage type frequency converter, the system selects the Mitsubishi 7K-CHT series FR-A740-3. Frequency converter. Its b
34、asic parameters: rated current of 12.6 A, the rated capacity of 9 kVA, allowing maximum motor power is 5.5 kW, the rated current for 150%, rated output voltage of 3 phase 380 V to 480 V, admissible voltage fluctuation of + 5%, be forced air cooling.This study selected variable frequency motor and in
35、verter configuration is reasonable, and its adjustment performance and the starting torque can meet the system requirements.4 CNC lathe experimental deviceNumerical control experimental device is a small experiment machine, speed range is not big, do not need to shift gears. Spindle speed control ex
36、perimental device wiring diagram as shown in Figure 1, the TA, TB, TC terminal connected to an external control circuit, PA, PB terminal used to brake, SVC, 0V terminal used to change the frequency, COM, SCW, SCCW terminal control motor positive inversion, QF air switch, with isolated power supply,
37、circuit breaker, too current, voltage and other protection.CNC Experiment Platform diagram as shown in figure 2. CNC lathe experimental system is the use of experimental control panel on the working table control, the panel can reflect each part of the operation condition. Failure in the panel show,
38、 make the system more intuitive, convenient for CNC lathe detection, repair and troubleshooting, and other aspects of learning. The design of variable frequency speed regulation system of NC lathe experiment is an important part of the system, the experimental system in CNC lathe, spindle speed by f
39、requency conversion motor and inverter with the use of variable frequency adjustable speed, a speed electromagnetic motor has the advantages of simple structure, convenient repair, and has high efficiency, obvious energy saving effect; speed smooth, wide scope, in 5 Hz 100 Hz range stepless speed re
40、gulation; small starting current, no additional starting equipment, low starting torque to the load impact is small; has the advantages of small volume, light weight, installation size and Y series of the same, particularly suitable for the experimental system used in NC lathe.5 endingApplication of
41、 frequency control of motor speed range is very wide, in the following 50 Hz can be used as a constant torque operation, more than 50 Hz for constant power operation, is an ideal speed control mode. For NC lathe spindle speed control system of VVVF, because of its superior performance, high efficien
42、cy and energy saving starter, wide speed range, high precision, stepless speed regulation has been widely used, and gradually replace the DC motor speed control. AC frequency converter and frequency conversion motor variable frequency speed control system application in the numerical control lathe,
43、experimental system, more convenient for inspection, repair and troubleshooting, and other aspects of learning, has very high practical value. References1 Ding Jinfu, Yu Fujin. The frequency conversion and speed regulation technology in CNC lathe application J . New technology and new process, 2005
44、( 5): 13-15.2 Zhou Hong, Zhou Wenjun. Numerical control lathe spindle speed realization J . Machine tool & hydraulics, 2007, 35 ( 1): 60-62.3 Zhu Quanyin, Han Laiji, Fu Yunqiang, et al. Numerical control machine tool spindle speed control system theory and application J . Coal mine machinery, 2009,
45、30 ( 9): 194-196.4 Chen Hequan. Frequency basic method ( J ). Industrial automation, 2010 ( 2): 122-125.5 Huang Guanyao, Liu Baohe. Mechanical manufacturing technology base M . Tiianjin: Tianjin University press, 19996 Helped Yu Peng, Huang Shou. The three-phase induction motor variable frequency sp
46、eed regulating effect ( J ). The explosion-proof motor, 2000 ( 3): 6-9.数控车床实验系统的主轴变频调速系统设计分析 郑艳琴，唐学哲( 浙江工业大学机械工程学院，浙江杭州310014)摘要:主要针对要求高精度、快响应的数控车床主轴调速系统的设计要求，通过对变频调速的基本原理和变频方式的分析，提出了变频电机与变频器组合的调速方案。根据数控车床实验系统的运行条件，计算车床的切削力和主轴电机的功率，为选择实验系统的主轴变频调速电机提供依据。根据选定的变频电机的特性，提出了变频器的选择原则，进而选择了额定容量和额定电流均与变频电机匹配
47、的，且采用矢量控制高性能型通用电压型变频器。最后，简要介绍了数控车床实验平台的设计思路。研究结果表明，选择的变频电机与变频器配置合理且其调整性能和启动转矩均能满足实验系统的要求。关键词:变频调速; 变频电机; 变频器; 数控车床0 引言随着现代工业技术的发展，变频调速技术在机械加工中已得到广泛的应用。在数控车床实验系统中，主轴旋转精度决定了零件的加工精度，变频调速调节数控机床主轴的转速，具有高效率、宽范围、高精度的特点，主轴调速越来越多地采用变频调速。从主轴调速系统的总体性能指标出发，如何正确选择电机和变频器，求得电机与变频器的最佳配合，是主轴变频调速系统设计的关键。本研究主要探讨数控车床实验系统的主轴变频调速系统的设计。1 变频调速的基本原理交流感应电动机的转速为:n0 = n( 1 s) = 60f( 1 s) /p ( 1)式中: f定子电源频率，s转差率，p磁场极对数。由式( 1) 知，改变电源的频率f，电动机转子转速就随之得到调节，这就是变频调速。变频器利用电力半导体器件的通断作用，可以将工频电源变换为另一频率的电源，提供电动机无级调速所需要的电压、频率，实现异步电动机的平滑调速。变频器实现变频的方式主要有交流-交流变频和交流-直流-交流变频( 直接转矩控制变频或矢量控制变频) 。交流-交流变频就是改变晶闸管导通控制角的大小和变化的频率，实现交流-交流的电
