• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Modal and harmonic response analysis of spindle system on CNC worm wheel gear grinding machine

    2014-06-04 11:15:06HonggangMUJinquanZHANGXianggenXUYeCHENNanjing0094JiangnanMineElectricMachineryZhenjiang009
    機床與液壓 2014年12期

    Hong-gang MU,Jin-quan ZHANG,Xiang-gen XU,Ye CHEN,Nanjing 0094,;Jiangnan Mine Electric Machinery,Zhenjiang 009,

    1.Introduction

    Modern machinery manufacturing industry is developing rapidly towards direction of high-speed,high-efficiency and high-precision.The continuous grinding method is employed by five axis Y7232CNC worm wheel gear grinding machine with characteristics of high speed and efficiency.The grinding wheel spindle is driven by built-in servo direct drive motor.The maximum speed of wheel spindle reaches 7 000 r/min.The maximum grinding speed achieves 90 m/s,and the highest grinding precision of gears reaches IT3.As a core component of high-end CNC grinding machine,the spindle system has the characteristics of simple harmonic vibration in grinding process because of its high speed.The dynamics of the spindle system directly affects the stability and reliability of the CNC grinding machine etc.,and then affects the grinding precision of gears.

    The dynamics of the spindle system and the machining accuracy of the grinding machine submit a direct relationship,so the research on the dynamics of spindle system has always become a hot topic.Luo Xiaoyingstudied dynamics of the spindle system in the spiral bevel gear grinding machine[1].The research indicated that the different structure parameters had an impact on the natural frequencies of the spindle system.Yu Tianbiao considered the supporting stiffness of liquid hybrid bearing and rotating prestressing force produced in the process of high grinding,and the modal analysis of the spindle system was carried out on ultra-high-speed grinding machine[2].The results showed that the supporting stiffness of the liq-uid hybrid bearing was dependent on the spindle speed.With the increase of the spindle speed,the natural frequencies of the spindle system were increased.Cai Ligang considered the radial stiffness of the spindle bearing,and the modal analysis of spindle was conducted[3].It was shown that the simulation results were more accurate when the spindle was taken as the beam element model.Tian Jie studied the dynamics of the spindle on the magnetic suspension grinding machine[4].The relationship between the supporting stiffness and the natural frequency was obtained.The vibration harmonic analysis of the spindle on the mineral oil separator was undertaken by Zhao Zhiguo.The amplitude-frequency characteristic curve and the maximum stress were obtained when the resonance vibration occurred[5].

    Combined with previous studies on the dynamics of the spindle,the dynamics of the spindle system on Y7232CNC worm wheel gear grinding machine was studied by the author in this paper.The spindle system,mainly composing of electric spindle and wheel spindle,was the core component of the grinding machine.The natural frequencies,mode shapes,and resonance speed were obtained by finite element analysis,for the purpose of optimizing the structure of the spindle system,selecting a reasonable spindle speed and avoiding resonance vibration.

    2.Theory of modal analysis and harmonic response analysis

    For the multi-degree of freedom system,the kinetic equation can be described as

    Where[M],[C]and[K]respectively represent the system mass,damping,and stiffness matrices.x(t)is the displacement vector,andF(t)is the external load.

    The natural frequency is independent of the external load and the damping term is ignored when the modal analysis is made.Therefore,the dynamics equation of the multi-DOF system is as follows

    Assuming the system submits simple harmonic motion,then

    Where φ is the amplitude of the displacement vector,ω is the angular frequency of the simple harmonic motion,and θ is the initial phase angle.

    Substituting equation(3)into equation(2),

    Since equation(4)are established at any time,equation(4)can be described as

    If equation(5)has a nonzero solution,the following condition is met

    The eigenvalues ωiare obtained by solving equation(6),namely the natural frequencies of the free vibration system.Substituting eigenvalues into equation(5),the modes corresponding to the natural frequencies can be obtained.

    For harmonic response analysis,the general motion equations of system can be defined as

    Where[M],[C]and[K]respectively represent the system mass,damping,and stiffness matrices.x(t)is the displacement vector,and{f(t)}is the harmonic load.

    The external load and displacement vectors submit simple harmonic motion,assuming that the frequencies are the same and the phase angles are zero,in that case,

    Substituting equation(8)and equation(9)into equation(7),then

    In that way,the amplitude of the forced vibration can be obtained by solving the equation(10).

    3.Finite element model of the spindle system

    3.1.Spindle system model

    The spindle system of Y7232CNC worm wheel gear grinding machine includes five parts:electric spindle,wheel spindle,centering sleeve,chuck,and worm grinding wheel.The various components of the spindle system are connected by bolts or interference fit,in which electric spindle and wheel spindle are connected by interference fit.Given the complexity of the actual spindle system,the appropriate and reasonable simplification are needed in modeling,such as ignoring the threaded holes,chamfers,un-dercuts and so on.In this paper,three-dimensional modeling software is used to model the spindle system,and then the three-dimensional model is imported ANSYS software to carry out modal analysis and harmonic response analysis.The three-dimensional finite element model of the spindle system is shown in Figure 1.

    Figure 1.Three-dimensional and finite element model of the spindle system

    3.2.Supporting way of spindle system

    The spindle system is sustained by three pairs of angular contact ceramic ball bearings.As shown in Figure 1,the first pair of angular contact ball bearings are arranged in the position of Chuck.The second and the third pairs of angular contact ball bearings are respectively arranged on the front and the back of electric spindle.The angular contact ball bearings are used on the spindle system,which can not only withstand the bear radial load,but also the axial load.The axial load is smaller than the radial load,so it is not considered in this paper.The deformation of bearing is mainly caused by the radial load.Under the pressure of the radial load,the corresponding deformation of inner rings,outer rings,and rolling will occur,so it is needed to define a radial bearing stiffness of angular contact ball bearings.Figure 2 is the sketch of bearing-shaft fit.In Figure 2,the support of angular contact ball bearings is simplified,and the radial supporting stiffness of angular contact ball bearings is equivalent to the stiffness of the spring.

    The radial stiffnesskron angular contact ceramic ball bearings can be defined as[6]

    Where,Zrepresents the number of rolling;Dbis the rolling diameter of ball bearings;α is the contact angle of ball bearings;Fa0is the preload of ball bearing.

    According to formula(11),the radial supporting stiffness of the three positions from left to right on the spindle system is given in Table 1 when different parameters are selected.

    Figure 2.Sketch of bearing-shaft fit

    Table 1.The radial stiffness of angular contact ball bearings

    4.Modal analysis of the spindle system

    According to the radial supporting stiffness of ball bearing in Table 1,modal analysis of the spindle system is carried out in order to obtain the six-order natural frequencies and mode shapes.The first-order mode shape of the spindle system is the axial vibration of the wheel spindle,and the amplitude of wheel parts is maximum.The second-order and the thirdorder mode shapes of the spindle system are the bending vibration of the wheel spindle.The fourth-order mode shape is the axial vibration of the spindle system.The fifth and sixth-order mode shapes are the bending vibration of the electric spindle,and the middle of electric spindle has the maximum amplitude.In summary,it can be seen that the dominant modes of the spindle system are the axial vibration and the bending vibration.Due to space limitations,only the third-order mode shape of the spindle system is shown in Figure 3.

    Figure 3.Third-order modal shape of spindle system

    To study the effect of the supporting stiffness of ballbearing fornaturalfrequencies,the three schemes are selected,and the modal natural frequencies are shown in Table 2.It can be seen,with the increase of the radial supporting stiffness,the natural frequencies of the spindle system are increased.The first and the second-order natural frequencies increase significantly,and the third to the eighth-order natural frequencies increase to a small extent.The bearing stiffness is related to the contact angle,preload and so on.By increasing the preload of ball bearing,supporting stiffness can be increased and then the natural frequencies of the spindle system are improved,but the wear of the ball bearing is increased.Meanwhile,high temperature and sharp noise will happen.Therefore,it is important to choose the reasonable parameters.

    Table 2.Modal natural frequencies of the spindle system

    5.Harmonic response analysis of spindle system

    Figure 4 is a schematic diagram of the grinding force.When the gear is grinded,the grinding force can be decomposed into axial force,radial force and tangential force.Meanwhile,the tangential force is smaller than the radial force,so it can be ignored.The tangential grinding force is not signed in Figure 4.Because of the symmetry of the gear tooth profile,the axial grinding forces of the two tooth profiles can offset each other.In this paper,the radial force is taken as the amplitude of the simple harmonic motion.The purpose is to research the steady-state response of the spindle system under the pressure of the exciting force.

    Figure 4.Schematic diagram of the grinding force

    According to the papers,the formula of the radial grinding forceFrcan be defined as

    In the formula,CFrepresents the energy required the removal of chips of per unit volume.uc,uwrespectively represent the speed of wheel and gear.fris the radial feed.Bis the grinding width.α represents the half angle of the abrasive.

    The harmonic analysis is used to determine the steady-state response of the spindle system under the harmonic exciting force.The purpose of the harmonic response is to calculate the response curve correspondent to several frequencies of the spindle system.The peaks of the harmonic response will be found from the response curve.Depending on frequency characteristics curve,it is considered to verify whether the spindle system can overcome resonance,fatigue,and other hazards caused by forced vibration.

    According to the natural frequencies calculated by the modal analysis,when the harmonic analysis is implemented,the frequencies range of the exciting force is set from 0 to 1 600 Hz,in order to study the deformation-frequencies response of spindle system within the frequency ranges.Studies have shown that,when the frequencies of the exciting force are the same as the natural frequencies of the spindle system,the peak response or resonance vibration will happen.Figure 5 is the deformation-frequency response curve.The five distinct peaks appear in the response curve.Their frequencies ranges are respectively from 50 to 80 Hz,from 150 to 200 Hz,from 550 to 700 Hz,from 1300 to 1 400 Hz,and from 1 500 to 1 600 Hz.The maximum deformation occurs in the vicinity of 600 Hz,and it reaches 6.56 μm.It can be shown that these frequencies just correspond to the first-order,the second-order,the third-order,the fifth-order and the seventh-order natural frequencies.Therefore,when the frequencies of the exciting force are within the vicinity of the natural frequencies,the resonance vibration of the spindle system will happen.

    Figure 5.Deformation-frequency response curve

    6.Critical speed of the spindle system

    The critical speeds of the spindle system are corresponding to the speeds calculated by the natural frequencies.If the spindle system is operating at a critical speed,there will be severe vibration and noise.Thereby,machining accuracy will be greatly affected,and severe bending of the spindle will occur in the long run.The purpose of analyzing the critical speed is trying to make the spindle system work well.Meanwhile,the spindle speed should be as far as possible away from the critical speed to avoid the resonance vibration.According to the natural frequencies of the spindle system,it is calculated that the range of the first-order critical speed is from 3 800 to 4 100 r/min,and the range of the second-order critical speed is from 10 020 to 11 880 r/min.The maximum speed of Y7232 CNC worm wheel gear grinding machine is 7 000 r/min.In order to avoid resonance vibration,the spindle speed should try to avoid the first-order critical speed.As the spindle speed does not reach more than ten thousand per minute,the actual speed of the spindle system is far away from the second-order and higher critical speed and resonance vibration will not happen.

    7.Conclusion

    1)According to the modal analysis of the spindle system,it is found that the natural frequencies of the spindle system are influenced by the supporting stiffness.With the increase of the bearing stiffness,the natural frequencies of the spindle system have been increased,and the first two natural frequencies are greatly impacted by the supporting stiffness.It is also found that the wheel spindle is the weak link of the spindle system,and the bending vibration mode of the wheel spindle is the dominant mode shapes.So it may be considered to optimize the structure of the spindle system.

    2)According to the harmonic analysis of the spindle system,it is found that,when the frequencies of the exciting force are in the vicinity of the natural frequencies,the resonance vibration of the spindle system will happen.Especially,if the frequency of the exciting force is close to 600 Hz,the maximum peak response will appear in the deformation-frequency response curve,and the maximum valueis 6.56 μm.

    3)The first-order critical speed and the secondorder critical speed of the spindle system are calculated.Since the first-order critical speed is lower than the maximum speed of the spindle system,the operating speed of the spindle system should avoid the first critical speed in order to avoid the resonance vibration.The second-order critical speed is far greater than the maximum speed of the spindle,so the resonance will not occur.

    [1]Luo Xiaoying,Tang Jinyuan.Effect of structure parameters on dynamic properties of spindle system[J].Journal of mechanical engineering,2007,48(3):128-134.

    [2]Yu Tianbiao,Wang Xuezhi,et al.Modal analysis of spindle system on ultra-high speed grinder[J].Journal of mechanical engineering,2012,48(17):184-188.

    [3]Cai Ligang,Ma Shiming,et al.Finite element modeling and modal analysis of heavy-duty mechanical spindle under multiple constraints[J].Journal of mechanical engineering,2012,48(3):165-173.

    [4]Tian Jie,Li Xiangbin.Dynamic analysis for electric spindle rotor system of magnetic levitation grinder considering grinding force[J].China mechanical engineering,2010,21(24):3005-3008.

    [5]Zhao Zhiguo.Vibration modal and harmonic analysis of spindle in mineral oil dish-style separator.Coal mine machinery.2011,32(12):112-114.

    [6]Wu Liangsheng,Zhou Liang.Dynamic performance for GDH512 motorized spindle[J].Mechanical technology and machine,2010(2):21-25.

    内射极品少妇av片p| 午夜福利成人在线免费观看| 亚洲av一区综合| 成人特级av手机在线观看| 国产91精品成人一区二区三区| av国产免费在线观看| 婷婷精品国产亚洲av在线| 亚洲中文字幕一区二区三区有码在线看| 夜夜看夜夜爽夜夜摸| 老熟妇乱子伦视频在线观看| 两性午夜刺激爽爽歪歪视频在线观看| 国产激情偷乱视频一区二区| 啦啦啦韩国在线观看视频| 天堂影院成人在线观看| 特大巨黑吊av在线直播| 中文字幕精品亚洲无线码一区| 国产成人aa在线观看| 夜夜爽天天搞| 亚洲国产精品成人综合色| 少妇裸体淫交视频免费看高清| av在线天堂中文字幕| 国产黄a三级三级三级人| 国产一区二区在线av高清观看| 中文字幕人妻丝袜一区二区| 亚洲美女视频黄频| 国产成人系列免费观看| 日韩欧美精品v在线| 午夜免费成人在线视频| 伊人久久大香线蕉亚洲五| 成人国产一区最新在线观看| 国产精品久久久久久亚洲av鲁大| 午夜两性在线视频| 小说图片视频综合网站| 日本成人三级电影网站| 又紧又爽又黄一区二区| 久久香蕉精品热| 在线观看66精品国产| 亚洲av二区三区四区| 亚洲av中文字字幕乱码综合| 久久精品亚洲精品国产色婷小说| 免费一级毛片在线播放高清视频| 脱女人内裤的视频| 蜜桃久久精品国产亚洲av| 国产v大片淫在线免费观看| 熟女少妇亚洲综合色aaa.| 欧美一级毛片孕妇| 特大巨黑吊av在线直播| 校园春色视频在线观看| svipshipincom国产片| 精品午夜福利视频在线观看一区| 欧美日韩亚洲国产一区二区在线观看| 成熟少妇高潮喷水视频| 色综合欧美亚洲国产小说| 国产成人影院久久av| 亚洲欧美日韩卡通动漫| 久久天躁狠狠躁夜夜2o2o| 男插女下体视频免费在线播放| 免费观看的影片在线观看| 美女cb高潮喷水在线观看| 好男人在线观看高清免费视频| 女警被强在线播放| 好男人在线观看高清免费视频| 麻豆国产av国片精品| 熟女人妻精品中文字幕| 国产中年淑女户外野战色| 狂野欧美激情性xxxx| 日本三级黄在线观看| 好男人在线观看高清免费视频| 伊人久久精品亚洲午夜| 19禁男女啪啪无遮挡网站| 免费一级毛片在线播放高清视频| 亚洲av电影在线进入| 久久这里只有精品中国| 久久精品国产清高在天天线| 五月玫瑰六月丁香| 床上黄色一级片| 国产精品女同一区二区软件 | 欧美在线一区亚洲| 狠狠狠狠99中文字幕| 欧美xxxx黑人xx丫x性爽| 性色avwww在线观看| 最后的刺客免费高清国语| 一本久久中文字幕| 国产精品嫩草影院av在线观看 | 成人永久免费在线观看视频| 亚洲最大成人中文| 久久香蕉精品热| 国内少妇人妻偷人精品xxx网站| 91久久精品电影网| 欧美日本亚洲视频在线播放| 国产伦精品一区二区三区视频9 | 国产亚洲精品久久久com| 狂野欧美白嫩少妇大欣赏| 久久草成人影院| 级片在线观看| 波多野结衣巨乳人妻| 天天一区二区日本电影三级| 欧美最新免费一区二区三区 | 中文在线观看免费www的网站| 真实男女啪啪啪动态图| 看黄色毛片网站| 两性午夜刺激爽爽歪歪视频在线观看| 午夜两性在线视频| 亚洲真实伦在线观看| 国产蜜桃级精品一区二区三区| 久久这里只有精品中国| 亚洲av美国av| 亚洲熟妇熟女久久| 制服丝袜大香蕉在线| 最近最新中文字幕大全免费视频| 亚洲国产精品成人综合色| 国产淫片久久久久久久久 | 中文字幕熟女人妻在线| 国产黄色小视频在线观看| 桃红色精品国产亚洲av| 免费观看的影片在线观看| 日本黄色片子视频| 制服人妻中文乱码| 香蕉久久夜色| 网址你懂的国产日韩在线| 亚洲中文字幕一区二区三区有码在线看| 嫩草影视91久久| 久久精品夜夜夜夜夜久久蜜豆| 变态另类丝袜制服| 18禁在线播放成人免费| 一区二区三区免费毛片| 精品无人区乱码1区二区| 精品99又大又爽又粗少妇毛片 | 国产蜜桃级精品一区二区三区| 老汉色av国产亚洲站长工具| 观看美女的网站| 色精品久久人妻99蜜桃| 女警被强在线播放| 日本黄色片子视频| 欧美中文综合在线视频| 免费av观看视频| 亚洲一区二区三区不卡视频| 两性午夜刺激爽爽歪歪视频在线观看| 久久精品91蜜桃| 亚洲成人中文字幕在线播放| 国产精品,欧美在线| 国产亚洲欧美在线一区二区| 亚洲av电影在线进入| 日韩欧美精品免费久久 | 99精品久久久久人妻精品| 久久婷婷人人爽人人干人人爱| 日韩人妻高清精品专区| 午夜福利18| 国产av不卡久久| 欧美成人a在线观看| 精品无人区乱码1区二区| 欧美另类亚洲清纯唯美| 免费在线观看日本一区| 在线十欧美十亚洲十日本专区| 国内少妇人妻偷人精品xxx网站| 国产一区二区在线观看日韩 | 99国产精品一区二区蜜桃av| 免费观看的影片在线观看| 久久精品国产99精品国产亚洲性色| 久久人妻av系列| 国产精品99久久久久久久久| 国产老妇女一区| 91av网一区二区| 亚洲国产欧美人成| 午夜亚洲福利在线播放| 午夜精品久久久久久毛片777| 亚洲久久久久久中文字幕| 中文字幕高清在线视频| 在线a可以看的网站| 午夜影院日韩av| 亚洲18禁久久av| 国产精品久久久久久人妻精品电影| 女警被强在线播放| 日韩欧美国产在线观看| 亚洲无线观看免费| 久久香蕉精品热| 麻豆成人av在线观看| 无遮挡黄片免费观看| 日韩欧美三级三区| 制服丝袜大香蕉在线| 免费看十八禁软件| 老司机福利观看| 午夜视频国产福利| 老司机在亚洲福利影院| 好男人电影高清在线观看| 一进一出好大好爽视频| av在线天堂中文字幕| 禁无遮挡网站| 久久精品国产99精品国产亚洲性色| 美女被艹到高潮喷水动态| 亚洲av二区三区四区| 国产午夜精品久久久久久一区二区三区 | 一区二区三区免费毛片| 亚洲成a人片在线一区二区| 亚洲人成网站高清观看| 亚洲av五月六月丁香网| 久久人人精品亚洲av| АⅤ资源中文在线天堂| 99国产精品一区二区蜜桃av| 欧美3d第一页| 波多野结衣巨乳人妻| 国内精品美女久久久久久| www.色视频.com| 免费人成视频x8x8入口观看| 日本撒尿小便嘘嘘汇集6| 国产精品电影一区二区三区| 亚洲中文字幕日韩| 国产免费av片在线观看野外av| 99国产综合亚洲精品| 国产真实乱freesex| 国产成人a区在线观看| 岛国在线观看网站| 国产老妇女一区| 午夜免费成人在线视频| 久久这里只有精品中国| 黄片小视频在线播放| 久久6这里有精品| 精品无人区乱码1区二区| 精品国内亚洲2022精品成人| 久久国产精品影院| eeuss影院久久| 欧美性感艳星| 免费观看的影片在线观看| 国产av一区在线观看免费| 国产精品国产高清国产av| 亚洲精品一区av在线观看| 国产一区二区亚洲精品在线观看| 精品欧美国产一区二区三| 国产精品一区二区免费欧美| 欧美精品啪啪一区二区三区| 人人妻人人澡欧美一区二区| 久久精品综合一区二区三区| 日韩欧美精品免费久久 | 又爽又黄无遮挡网站| 国内精品久久久久精免费| 动漫黄色视频在线观看| 他把我摸到了高潮在线观看| 观看美女的网站| 美女高潮的动态| 亚洲午夜理论影院| 又粗又爽又猛毛片免费看| 久久久久久大精品| 国产成人aa在线观看| 美女被艹到高潮喷水动态| 在线观看66精品国产| 丰满的人妻完整版| 在线观看午夜福利视频| 亚洲精品456在线播放app | 亚洲欧美日韩卡通动漫| 久久久国产成人精品二区| 中文字幕高清在线视频| 国产极品精品免费视频能看的| 天堂动漫精品| 亚洲五月婷婷丁香| 日本在线视频免费播放| 亚洲精品一卡2卡三卡4卡5卡| 色噜噜av男人的天堂激情| 国产精品久久视频播放| 18禁裸乳无遮挡免费网站照片| 日韩亚洲欧美综合| 欧美国产日韩亚洲一区| 三级男女做爰猛烈吃奶摸视频| 国产三级在线视频| 黄色视频,在线免费观看| 一进一出抽搐动态| 一级毛片女人18水好多| 亚洲成人免费电影在线观看| 久久婷婷人人爽人人干人人爱| 国产精品久久久久久人妻精品电影| 亚洲国产中文字幕在线视频| 亚洲国产精品合色在线| 在线视频色国产色| 日本a在线网址| 精品午夜福利视频在线观看一区| 国产精品国产高清国产av| 男人舔女人下体高潮全视频| 日日干狠狠操夜夜爽| 欧美成人免费av一区二区三区| 成年版毛片免费区| 婷婷六月久久综合丁香| 99久久无色码亚洲精品果冻| 日韩欧美在线二视频| www日本在线高清视频| 午夜福利欧美成人| 狠狠狠狠99中文字幕| 久久久国产成人精品二区| 熟妇人妻久久中文字幕3abv| 91av网一区二区| 夜夜爽天天搞| 欧洲精品卡2卡3卡4卡5卡区| 欧美不卡视频在线免费观看| 久久婷婷人人爽人人干人人爱| 中国美女看黄片| 成人18禁在线播放| 白带黄色成豆腐渣| 国产成年人精品一区二区| 嫁个100分男人电影在线观看| 国产成人欧美在线观看| 国产亚洲精品综合一区在线观看| 国产男靠女视频免费网站| 午夜亚洲福利在线播放| 欧美中文日本在线观看视频| 99国产精品一区二区三区| 免费看a级黄色片| 99国产综合亚洲精品| 国产v大片淫在线免费观看| 精品福利观看| 在线免费观看的www视频| tocl精华| 中文字幕久久专区| 91久久精品电影网| 亚洲内射少妇av| 国产美女午夜福利| 韩国av一区二区三区四区| 国产三级在线视频| 欧美激情在线99| av黄色大香蕉| 色哟哟哟哟哟哟| 欧美一区二区国产精品久久精品| 桃色一区二区三区在线观看| 少妇高潮的动态图| av欧美777| 亚洲五月婷婷丁香| 可以在线观看毛片的网站| 99国产极品粉嫩在线观看| 亚洲欧美一区二区三区黑人| 精品99又大又爽又粗少妇毛片 | 久久午夜亚洲精品久久| 久久国产精品人妻蜜桃| 国产爱豆传媒在线观看| 俄罗斯特黄特色一大片| 一卡2卡三卡四卡精品乱码亚洲| 成人国产综合亚洲| 欧美午夜高清在线| 欧美成狂野欧美在线观看| 成人一区二区视频在线观看| 好男人电影高清在线观看| 亚洲七黄色美女视频| 天堂影院成人在线观看| 国产高清视频在线播放一区| 欧美性猛交╳xxx乱大交人| 内地一区二区视频在线| 亚洲国产高清在线一区二区三| 成人特级av手机在线观看| 国产精品久久久久久久久免 | 日韩欧美在线二视频| 国产亚洲精品久久久久久毛片| 欧美黄色片欧美黄色片| 亚洲人成电影免费在线| 亚洲中文日韩欧美视频| 国产野战对白在线观看| 国内毛片毛片毛片毛片毛片| 一卡2卡三卡四卡精品乱码亚洲| 免费无遮挡裸体视频| 日韩欧美三级三区| 美女 人体艺术 gogo| 免费看光身美女| 免费av毛片视频| 久久久色成人| 欧美日本视频| 免费看a级黄色片| 久久亚洲真实| 丰满人妻熟妇乱又伦精品不卡| 夜夜看夜夜爽夜夜摸| 国产黄a三级三级三级人| 成年免费大片在线观看| 白带黄色成豆腐渣| 久久精品国产清高在天天线| 美女cb高潮喷水在线观看| 99久久精品一区二区三区| av天堂在线播放| 最近最新中文字幕大全免费视频| 国产综合懂色| 每晚都被弄得嗷嗷叫到高潮| 变态另类丝袜制服| 午夜精品久久久久久毛片777| 久久精品国产综合久久久| 久久婷婷人人爽人人干人人爱| 好男人在线观看高清免费视频| 一级毛片高清免费大全| 在线视频色国产色| 欧美xxxx黑人xx丫x性爽| 国产色婷婷99| 波多野结衣高清无吗| 欧美zozozo另类| 国产又黄又爽又无遮挡在线| 欧美又色又爽又黄视频| 叶爱在线成人免费视频播放| 丰满人妻熟妇乱又伦精品不卡| 亚洲中文字幕一区二区三区有码在线看| 88av欧美| 免费看日本二区| 亚洲 欧美 日韩 在线 免费| or卡值多少钱| 亚洲精品乱码久久久v下载方式 | 国内精品久久久久精免费| 久久久久亚洲av毛片大全| 嫩草影院入口| 国产色婷婷99| 亚洲自拍偷在线| 成人午夜高清在线视频| 久久人妻av系列| 91字幕亚洲| 精品久久久久久久毛片微露脸| 国产v大片淫在线免费观看| 久久国产精品影院| 天堂动漫精品| 国产中年淑女户外野战色| 欧美乱码精品一区二区三区| 国产成人系列免费观看| 国产亚洲精品久久久com| 国产亚洲精品一区二区www| 一a级毛片在线观看| 性色avwww在线观看| 欧美日本视频| 国产精品久久久人人做人人爽| 免费观看的影片在线观看| 免费一级毛片在线播放高清视频| 亚洲自拍偷在线| 亚洲欧美日韩卡通动漫| 级片在线观看| 12—13女人毛片做爰片一| 亚洲av日韩精品久久久久久密| 久久草成人影院| 又紧又爽又黄一区二区| 国产一区二区激情短视频| 婷婷丁香在线五月| 熟女电影av网| 九色成人免费人妻av| 美女高潮的动态| www日本在线高清视频| 国产精品日韩av在线免费观看| 亚洲人成网站在线播| 日本黄色视频三级网站网址| 国产精品爽爽va在线观看网站| av黄色大香蕉| 国内少妇人妻偷人精品xxx网站| 欧美性猛交╳xxx乱大交人| 国产精品一区二区免费欧美| 国内揄拍国产精品人妻在线| 国产97色在线日韩免费| 啦啦啦韩国在线观看视频| 搡老熟女国产l中国老女人| 精品乱码久久久久久99久播| 中出人妻视频一区二区| 久久久久久九九精品二区国产| 女人十人毛片免费观看3o分钟| 波多野结衣巨乳人妻| 精品乱码久久久久久99久播| 少妇的丰满在线观看| 99久久久亚洲精品蜜臀av| 嫩草影院入口| 国产伦一二天堂av在线观看| www.999成人在线观看| 亚洲第一欧美日韩一区二区三区| 91字幕亚洲| 国产亚洲精品久久久com| 搡老熟女国产l中国老女人| 国产精品,欧美在线| 91麻豆av在线| 男人舔奶头视频| 男人和女人高潮做爰伦理| 三级男女做爰猛烈吃奶摸视频| 免费观看人在逋| 免费人成在线观看视频色| 久久久久久久久大av| 首页视频小说图片口味搜索| 夜夜看夜夜爽夜夜摸| 91久久精品国产一区二区成人 | 老熟妇仑乱视频hdxx| 69av精品久久久久久| 91九色精品人成在线观看| 少妇的逼好多水| 观看免费一级毛片| 国产真实伦视频高清在线观看 | 欧美在线黄色| 一级黄片播放器| 亚洲一区二区三区色噜噜| 老鸭窝网址在线观看| 在线播放无遮挡| 欧美黑人欧美精品刺激| 高清在线国产一区| 啦啦啦免费观看视频1| 在线免费观看不下载黄p国产 | x7x7x7水蜜桃| 色哟哟哟哟哟哟| 18禁裸乳无遮挡免费网站照片| 99国产精品一区二区三区| 午夜福利免费观看在线| 观看免费一级毛片| 亚洲片人在线观看| 女人被狂操c到高潮| 亚洲 国产 在线| 男人的好看免费观看在线视频| 成人国产综合亚洲| 一夜夜www| 国产伦在线观看视频一区| 久久久久久久午夜电影| 亚洲在线观看片| 高清日韩中文字幕在线| 亚洲avbb在线观看| 美女免费视频网站| 色视频www国产| 国产精品综合久久久久久久免费| 国产精华一区二区三区| 国产精品国产高清国产av| 香蕉丝袜av| 中文字幕高清在线视频| 床上黄色一级片| 中文在线观看免费www的网站| 国产精品香港三级国产av潘金莲| 成年免费大片在线观看| 久久欧美精品欧美久久欧美| 青草久久国产| 小说图片视频综合网站| 欧美黑人巨大hd| 婷婷亚洲欧美| 91在线精品国自产拍蜜月 | 天堂√8在线中文| 男女那种视频在线观看| 黄片小视频在线播放| 九色国产91popny在线| 日本 av在线| 亚洲第一欧美日韩一区二区三区| 成人国产一区最新在线观看| 99精品久久久久人妻精品| 12—13女人毛片做爰片一| 男人的好看免费观看在线视频| 亚洲 欧美 日韩 在线 免费| 久久久久九九精品影院| 动漫黄色视频在线观看| 亚洲五月婷婷丁香| 国产99白浆流出| 禁无遮挡网站| 九九在线视频观看精品| 在线观看午夜福利视频| 国产老妇女一区| 久久久久国内视频| 日本成人三级电影网站| 成人无遮挡网站| 国内精品一区二区在线观看| 俄罗斯特黄特色一大片| 一边摸一边抽搐一进一小说| 精品福利观看| 午夜福利在线观看吧| 亚洲人成网站在线播放欧美日韩| 亚洲精品久久国产高清桃花| 黄色成人免费大全| 啪啪无遮挡十八禁网站| 在线十欧美十亚洲十日本专区| 亚洲aⅴ乱码一区二区在线播放| 国产精品一区二区三区四区免费观看 | 久久亚洲精品不卡| 免费看日本二区| 欧美bdsm另类| 色尼玛亚洲综合影院| 国产精品香港三级国产av潘金莲| 国产成人欧美在线观看| 91av网一区二区| 一卡2卡三卡四卡精品乱码亚洲| avwww免费| 尤物成人国产欧美一区二区三区| 高清日韩中文字幕在线| 观看免费一级毛片| 国产成年人精品一区二区| 欧美一级a爱片免费观看看| 亚洲av美国av| 成人一区二区视频在线观看| 国产亚洲欧美在线一区二区| 人人妻人人看人人澡| 嫩草影院精品99| 久久精品国产亚洲av涩爱 | 大型黄色视频在线免费观看| 欧美日韩福利视频一区二区| 嫩草影视91久久| 99久久精品国产亚洲精品| 国产精品久久久久久亚洲av鲁大| 51国产日韩欧美| 婷婷精品国产亚洲av在线| 一级黄片播放器| 日韩成人在线观看一区二区三区| 欧美成人免费av一区二区三区| av欧美777| 日本三级黄在线观看| 国产91精品成人一区二区三区| 国产在线精品亚洲第一网站| 麻豆国产97在线/欧美| 在线播放无遮挡| 岛国在线免费视频观看| 在线观看66精品国产| 一个人免费在线观看电影| 久久精品国产亚洲av涩爱 | 在线观看av片永久免费下载| 一进一出抽搐动态| 国产三级在线视频| 欧美另类亚洲清纯唯美| 亚洲激情在线av| 亚洲欧美日韩高清在线视频| 国产一区二区三区在线臀色熟女| 欧美高清成人免费视频www| 狠狠狠狠99中文字幕| 黄色日韩在线| 日韩亚洲欧美综合| 国产精品久久久久久亚洲av鲁大| 国产97色在线日韩免费| 久久亚洲精品不卡| 日本一本二区三区精品| 亚洲精品国产精品久久久不卡| 9191精品国产免费久久| 香蕉丝袜av| 波野结衣二区三区在线 | 精品一区二区三区av网在线观看| 一二三四社区在线视频社区8| 一区二区三区国产精品乱码| а√天堂www在线а√下载|