1、目 錄1 spindle variable speed system design and analysis forcnc lathe experiment system····································

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3、;·························12 數控車床實驗系統的主軸變頻調速系統設計分析·····················

4、;·····················6spindle variable speed system design and analysis for cnc lathe experiment systemzheng yan-qin，tang xue-zhe( school of mechanical engineering，zhejiang university of technol

5、ogy，hangzhou 310014，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

6、 speed controlaccording 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 principl

7、e of choosing transducer 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

8、describedthe frequency 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

9、 industrial technology, 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 spee

10、d, high efficiency, 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 de

11、sign of variable frequency 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 freq

12、uency, s, slip, p - 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 anot

13、her frequency stepless 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

14、direct torque control 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

15、power, and then by 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 spindl

16、e speed control experiment 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

17、of experiments, the 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 ) empiric

18、al formula:fz = cfz·axfzp ·fyfz·vnfzfy = cfy·axfyp ·fyfy·vnfyfx = cfx·axfx·fyfx·vnfz nfxp ·fyfx·v 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 - f

19、eed the workpiece diameter. when turning, fz than fy, fx is much greater, and fy, fx 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 81cfz·axfzp ( 3)accor

20、ding to the numerical control lathe experimental system operating conditions, to take: cfz = 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 ef

21、ficiency for m = 0.75, then the nc machine tool spindle motor power pe > pm / m = 3.687 kw.fed 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 a

22、rbitrary translation, which enable asynchronous motor performance is improved greatly. therefore, 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 fram

23、e size as far as possible the same strength; the cutting and processing of the heterogeneity of 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 mo

24、tor rated power, rated torque of 5.5 kw, 30 n m, the rated current of 12 a, with similar frequency 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, a

25、nd experimental systementry requirements. the main technical indexes for the three-phase voltage: 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 boo

26、sting, ensure the motor in 5 hz rated output torque and the motor for heating and burning.3 inverter 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;

27、 the inverter load performance curve; the frequency converter and load matching problem of the 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 o

28、verload capacity, in the constant torque or speed reducing device should also pay attention to 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 th

29、e common motor selection; the cable, motor on the coupling capacitance exists, also can cause the 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 ser

30、ious, cannot realize energy recycling, in demanding situations, rectifying and inverting process 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

31、 connected in parallel, must with total current does not exceed the rated current for the principle 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

32、× 10 3 ( kva)icnkim( a) ( 4)type : pm - load required motor power output shaft; the eta, the efficiency 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 ); pc

33、n inverter rated capacity, kva; icn, the rated current of the inverter, a.frequency converter and asynchronous 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 conti

34、nuous operation, the three are unified, selection of frequency inverter capacity should meet 3 formula.in the 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 v

35、oltage 380 v, rated at 5.5 kw, select the converter capacity and rated current should satisfy the type:pcnkpmcos = 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

36、 system, the original use of dc transmission. at present, vector control inverter has been universal, for the requirements of high precision, 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

37、capacity inverter with voltage type frequency converter, the system selects the mitsubishi 7k-cht series fr-a740-3. frequency converter. its basic 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 voltag

38、e of 3 phase 380 v to 480 v, admissible voltage fluctuation of + 5%, be forced air cooling.this study selected variable frequency motor and inverter configuration is reasonable, and its adjustment performance and the starting torque can meet the system requirements.4 cnc lathe experimental devicenum

39、erical control experimental device is a small experiment machine, speed range is not big, do not need to shift gears. spindle speed control experimental 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, 0

40、v terminal used to change the frequency, com, scw, sccw terminal control motor positive inversion, qf air switch, with isolated power supply, 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 e

41、xperimental control panel on the working table control, the panel can reflect each part of the operation condition. failure in the panel show, make the system more intuitive, convenient for cnc lathe detection, repair and troubleshooting, and other aspects of learning. the design of variable frequen

42、cy speed regulation system of nc lathe experiment is an important part of the system, the experimental system in cnc lathe, spindle speed by frequency conversion motor and inverter with the use of variable frequency adjustable speed, a speed electromagnetic motor has the advantages of simple structu

43、re, convenient repair, and has high efficiency, obvious energy saving effect; speed smooth, wide scope, in 5 hz 100 hz range stepless speed regulation; small starting current, no additional starting equipment, low starting torque to the load impact is small; has the advantages of small volume, light

44、 weight, installation size and y series of the same, particularly suitable for the experimental system used in nc lathe.5 endingapplication of 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 op

45、eration, is an ideal speed control mode. for nc lathe spindle speed control system of vvvf, because of its superior performance, high efficiency and energy saving starter, wide speed range, high precision, stepless speed regulation has been widely used, and gradually replace the dc motor speed contr

46、ol. ac frequency converter and frequency conversion motor variable frequency speed control system application in the numerical control lathe, experimental system, more convenient for inspection, repair and troubleshooting, and other aspects of learning, has very high practical value. references1 din

47、g jinfu, yu fujin. the frequency conversion and speed regulation technology in cnc lathe application j . new technology and new process, 2005 ( 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,

48、 han laiji, fu yunqiang, et al. numerical control machine tool spindle speed control system theory and application j . coal mine machinery, 2009, 30 ( 9): 194-196.4 chen hequan. frequency basic method ( j ). industrial automation, 2010 ( 2): 122-125.5 huang guanyao, liu baohe. mechanical manufacturi

49、ng technology base m . tiianjin: tianjin university press, 19996 helped yu peng, huang shou. the three-phase induction motor variable frequency speed regulating effect ( j ). the explosion-proof motor, 2000 ( 3): 6-9.數控車床實驗系統的主軸變頻調速系統設計分析 鄭艷琴，唐學哲( 浙江工業大學機械工程學院，浙江杭州310014)摘要:主要針對要求高精度、快響應的數控車床主軸調速系統的

50、設計要求，通過對變頻調速的基本原理和變頻方式的分析，提出了變頻電機與變頻器組合的調速方案。根據數控車床實驗系統的運行條件，計算車床的切削力和主軸電機的功率，為選擇實驗系統的主軸變頻調速電機提供依據。根據選定的變頻電機的特性，提出了變頻器的選擇原則，進而選擇了額定容量和額定電流均與變頻電機匹配的，且采用矢量控制高性能型通用電壓型變頻器。最后，簡要介紹了數控車床實驗平臺的設計思路。研究結果表明，選擇的變頻電機與變頻器配置合理且其調整性能和啟動轉矩均能滿足實驗系統的要求。關鍵詞:變頻調速; 變頻電機; 變頻器; 數控車床0 引言隨著現代工業技術的發展，變頻調速技術在機械加工中已得到廣泛的應用。在數控

51、車床實驗系統中，主軸旋轉精度決定了零件的加工精度，變頻調速調節數控機床主軸的轉速，具有高效率、寬范圍、高精度的特點，主軸調速越來越多地采用變頻調速。從主軸調速系統的總體性能指標出發，如何正確選擇電機和變頻器，求得電機與變頻器的最佳配合，是主軸變頻調速系統設計的關鍵。本研究主要探討數控車床實驗系統的主軸變頻調速系統的設計。1 變頻調速的基本原理交流感應電動機的轉速為:n0 = n( 1 s) = 60f( 1 s) /p ( 1)式中: f定子電源頻率，s轉差率，p磁場極對數。由式( 1) 知，改變電源的頻率f，電動機轉子轉速就隨之得到調節，這就是變頻調速。變頻器利用電力半導體器件的通斷作用，可

52、以將工頻電源變換為另一頻率的電源，提供電動機無級調速所需要的電壓、頻率，實現異步電動機的平滑調速。變頻器實現變頻的方式主要有交流-交流變頻和交流-直流-交流變頻( 直接轉矩控制變頻或矢量控制變頻) 。交流-交流變頻就是改變晶閘管導通控制角的大小和變化的頻率，實現交流-交流的電壓和頻率的調整。利用晶閘管的導通性能，本研究先把工頻交流電源轉換成直流電源，再利用由晶閘管構成的逆變器主電路，輸出三相頻率和電壓均可調整、等效于正弦波的脈寬調制波( spwm 波) ，實現交流-直流-交流變頻，拖動三相異步電機調速運轉4-5。2 數控車床實驗系統主軸調速的變頻電機選擇由于切削過程的復雜性，影響切削力的因素非

53、常多，因此目前尚未導出簡便的計算切削力fx，fy，fz的理論公式，一般都是通過大量實驗，建立經驗公式來計算切削力。本研究將背吃刀量、進給量及切削速度3 個主要因素作為可變因素，而其他影響因素則用修正系數間接計算，可以得出fx，fy，fz 3 個分力的經驗公式6:fz = cfz·axfzp ·fyfz·vnfzfy = cfy·axfyp ·fyfy·vnfyfx = cfx·axfx·fyfx·vnfz nfxp ·fyfx·v nf ( 2) 式中: fz切削力; fy徑向力; f

54、x進給力; v切削速度，v = nd /( 1 000 × 60) ; n工件轉速; d工件直徑; f進給量。車削時，fz比fy，fx大得多，而且fy，fx方向上的運動速度又很小，因此，fy，fx所消耗的功率很小( 僅為1% 2%) ，故可忽略不計。適用于車床的切削力的計算公式如下:fz = 9 81cfz·axfzp ( 3)根據數控車床實驗系統的運行條件，取: cfz = 40，xfz = 1 0，yfz = 0 75，apmax = 6 mm，fmax = 0 2 mm/r，n = 2 500 mm/min，d = 30 mm。則切削功率pm = fz·v

55、× 10 3 = 704 13 × 3 93 × 10 3 = 2 765 kw。本研究取機床的傳動效率m = 0 75，則數控機床主軸電機功率pepm /m = 3 687 kw。變頻器供電下的異步電機運行條件發生了根本的變化7，電機運行時，隨著變頻器的調調壓控制，機械特性曲線可以任意平移，這使異步電機在性能上大大改善。所以，數控車床實驗系統變頻電機的選擇，還應考慮: 電機與車床主軸功率特性匹配問題; 變頻電機與普通電機機座號盡量相同; 強力切削和加工材料的不均勻性，主電機功率應有一定的儲備8-9。該實驗系統選用新鄉市特種電機制造有限公司的yvp 系列4 級變頻

56、電機，額定功為5 5 kw，額定轉矩30 n·m，額定電流為12 a，可與同類變頻裝置配套，互換性、通用強，其功率、底腳安裝尺寸和中心高等對應指標與y 系列異步電機完全一致，與實驗系統環境要求相符。主要技術指標為電壓: 三相380 v/50 hz; 變頻調速范圍: 5 hz 100 hz 無級調速。低速時轉矩平滑，無爬行現象; 能通過變頻裝置的電壓提升，保證電動機在5 hz 時輸出額定轉矩而不致使電機因發熱而燒毀。3 變頻器類型的選擇在數控車床實驗系統中，主軸調速變頻器的選型應注意: 變頻器是實現恒壓控制還是恒流控制; 變頻器的負載性能曲線; 變頻器與負載的匹配問題，變頻器的額定電壓、電流應與負載的額定電壓、電流相符，對于特殊的負載則需要參考電機性能參數，以最大電流確定變頻器電流和過載能力，在恒轉矩負載或有減速裝置時還應注意轉矩匹配; 考慮到高次諧波會導致輸出電流增大，變頻器驅動電機，特別是電抗小的高速電機，其容量應略大于普通電機的選型; 電纜、電機對地耦合電容的存在，也會引起電流增大，變頻器的容量應適當提高; 采用pwm 控制逆變器，整流器不可控的變頻器，功率因數相對較低、網側諧波污染嚴重、無法實現能量的再生利用，在要求較高的場合，整流和逆變過程都采用pwm 控制的雙pwm 變