亚洲免费av电影一区二区三区,日韩爱爱视频,51精品视频一区二区三区,91视频爱爱,日韩欧美在线播放视频,中文字幕少妇AV,亚洲电影中文字幕,久久久久亚洲av成人网址,久久综合视频网站,国产在线不卡免费播放

        ?

        Precision Measurement of Series Motor Housing Based on CMM

        2013-09-17 12:10:58JINChuanLIYing
        機(jī)床與液壓 2013年12期

        JIN Chuan,LI Ying

        Nanjing Institute of Industry Technology,Nanjing 210023,China

        1.Introduction

        With the development of society,mechanical and electrical products tend to be smaller size,more portable and low cost at the same time.So does the motor.

        Currently for small size motor,the motor housing is injected directly with plastic,especially for DC series motor.The material of injection is usually the nylon in which some glass fiber is added.Therefore,the cost of manufacturing will be comparatively decreased and manufacturing efficiency will be greatly improved.Another benefit of this is that the portability will be enhanced due to the using of less weight plastic material.

        However,the disadvantages are quiet obvious:Due to the deformation,the distance between location of stator and rotor on motor housing and the location of assembling with other part of motor housing will inevitably deviate from the original design.However,the parts inside motor have high precision requirements from the design point of view.Any interference between parts will lead to anomalous temperature rise even burn up for the range of rotation speed from 10,000 r/min to 20,000 r/min.

        Therefore,it is very important to control the precision of motor housing.

        In order to control the precision of motor housing,the key part is how to measure and assess it.Currently,CMM is widely used as measurement tool.The process of measurement is that detector gets some points data on workpiece,and then inputs to software to simulate the expected results.

        The advantage for this measurement is no need to rotate workpiece,no need to prepare a dedicated shaft or support,no need to do mechanical alignment,and the efficiency is very high with good repeatability[1].However,the disadvantages for this method are the measurement datum selection,it is the one of most important factors which will affect the measurement precision[2].

        This paper tries to take one power tool motor housing as example to analyze and find out how to choose an appropriate and reliable datum system for better precision measurement of motor housing.

        2.Assembly requirements for series motor

        The motor assembly structure is shown as Fig.1.One side of the rotor is positioned with a bearing in bearing seat on motor housing,another side of the rotor shaft is engaged with gear inside the tool.The motor housing structure is shown as Fig.2.There are 8 ribs holding the stator to keep the axis of stator be coaxial with the axis of rotor.The whole motor housing is positioned by four small assembly surfaces with fix plate,and is fixed with tool body by screws through assembly holes.

        For motor housing,the most important function is to keep stator central axis coaxial with the axis of rotor,so the coaxiality of these two axes will directly reflect the precision of the motor housing.

        Next we will focus on the measurement of coaxiality for the motor housing.

        Fig.1 Motor assembly structure

        Fig.2 Motor housing structure

        3.Measurement methods development

        The central axis of motor housing,the central axis of stator should be coaxial with central axis of rotor from design point of view,but the coaxiality of the axis can not be measured directly by CMM.It is necessary to transfer the measured object to some basic elements such as circle,plane,cylinder and cone.Then using CMM to measure these basic elements and calculate by using Calypso software to get expected results[3].For this motor housing measurement,we can transfer the axis to the line which connects two circle center points.How to use the existing geometric features on the motor housing or on the stator to simulate the circles and then connect two centers to create the alternative line will directly affect the measurement deviation,therefore,the measurement datum is the key.

        Next,we will use three different measurement datum to measure the coaxiality.

        3.1.Method 1,Directly taking measurement datum on motor housing inside surfaces

        Taking points directly with CMM on motor housing bearing seat internal surface,assembly surfaces,down side of the motor housing ribs and top side of the motor housing ribs,and then the program simulate the data of points to the four circles as shown in Fig.3.At the same time,the program calculates the centers for each circle automatically as O1,O2,O3and O4,and then we can create line O1O2by connecting point O1and point O2,and by using the same way to create line O2O3.

        So we can take line O1O2as central axis of rotor,and take line O2O3as central axis of stator,then the coaxiality measurement is transferred to the measurement between these two lines.

        Fig.3 Direct Measurement on motor housing

        3.2.Method 2,Taking measurement datum from assembled fix plate and stator

        Firstly,we need assemble the stator and fix plate into the motor housing and then fix with screws as shown in Fig.4,and then take points with CMM on the bearing seat internal surface,internal surface of fixed plate and internal surfaces of stators.The program simulates the points data to the four circles as P4shows.At the same time,the program calculates the centers for each circle automatically as O1,O2,O3and O4,and then we can create line O1O2by connecting point O1and point O2,and same way to create line O2O3.

        Same as method 1,we could evaluate the coaxiality of line O1O2and line O3O4to reflect the coaxiality of stator and rotor.

        Fig.4 Take measurement datum from assembled fix plate and stator

        3.3.Method 3,Taking measurement datum with“Best Fit”function

        Same as method 2,assemble stator into the motor housing to get points O1,O3and O4following the same process as before.

        Next we will use the“Best Fit”function of CMM to create O2.Firstly,we need take points from the whole four assembly holes,and then the program will apply these hole position data with the method of least squares to get the closest center point O2as shown in Fig.5.

        So we can get line O1O2and line O3O4to measure the coxaility.

        Fig.5 Measure with best fit function

        4.Measurement results comparison and analysis

        Following the 3 methods,the measurement results are shown in Tab.1.

        From the measurement results,we can see that Method 1 has the greatest measurement deviation and poor repeatability,Method 2 is better and Method 3 is the best one.

        Tab.1 Measurement results of coaxiality mm

        The above difference could be explained as follows:

        For the Method 1,we take points directly on the surfaces of motor housing ribs,but motor housing is injected out of mold,the ribs has draft angle for easier release from mold,that means the detector will get different data with different section;On the other hand,since the ribs are very thin,they are easy to be deformed during the process out of mold.So it is hard to get the reliable and repeatable results by such kind of point data.The similar situation for the assembly surfaces as the area is too small.

        For the Method 2,although it avoids the disadvantages of Method1,but assembly process will lead to the deformation of the motor housing,especially for the fix plate.Because the open end of the motor housing normally has more deformation after it comes out of the mold,and the flatness of the open end surface becomes worse,if the fix plate is assembled on in this situation,the deviation occurs.

        For the Method 3,it overcomes the disadvantages for the both methods as mentioned above,so it could get better results.

        5.Conclusions

        The precision of motor housing will directly affect the motor precision and life.It needs to be measured with reliable and repeatable method to control the precision.According to the measurement results,the control of manufacturing process will help to improve the motor precision and lifespan.

        [1] ZHANG Furong,ZHANG Tingjun.Measurement of Coaxiality CMM-based[J].Machine Buliding & Automation,2009(5):64-65.

        [2] LIUZhaoping.App lication of Coaxiality Measurement on CMM[J].PRECISE MANUFACTURING & AUTOMATION,2010(3):61-63.

        亚洲暴爽av人人爽日日碰| 日本av天堂一区二区三区| 美腿丝袜中文字幕在线观看| 亚洲视频在线观看青青草| 亚洲天堂一区二区三区| 一本色道久久亚洲综合| 午夜性刺激免费看视频| 久久午夜福利电影| 国内精品久久久久影院优| 岛国av无码免费无禁网站| 亚洲综合精品伊人久久| 福利视频一二三在线观看| 色婷婷综合中文久久一本| 日日摸夜夜添无码无码av| 精品无人区无码乱码大片国产| 欧美日韩亚洲国产无线码| 激情在线视频一区二区三区| 亚洲av一区二区在线| 国产精品久久免费中文字幕| 大地资源网高清在线播放| 亚洲熟伦熟女新五十路熟妇| 国产h视频在线观看网站免费| 午夜一区二区三区在线观看| 日韩人妻精品中文字幕专区| 少妇性l交大片7724com| 欧美成人精品午夜免费影视| 亚洲国产精品日韩av专区| 精品香蕉久久久午夜福利| 黑人巨大videos极度另类 | 久久精品亚洲乱码伦伦中文| 国产精品亚洲专区无码web | 亚洲国产精品无码专区在线观看| 精品一区二区久久久久久久网站 | 日韩国产人妻一区二区三区| 国产精品久久国产三级国不卡顿| 国产精品国产三级国产专播| bbbbbxxxxx欧美性| 日韩成人精品一区二区三区| 国产熟女露脸大叫高潮| 日韩美女av一区二区三区四区| 亚洲无av在线中文字幕|