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1、difficult, not hating; blueprints, not rhetoric; words and simple, but full of love, truth, passion, entrepreneurial passion. Take this opportunity, my inspirational quotes Li Dazhaos classic iron specialise in uplifting blend with the article gave everyone, with a view on how to do well under the n
2、ew situation of township and village leaders inspire and help, and also share with you. A good play to create iron shoulders strong arms, to assume the burden be passed; only specific qualities, will it be possible in specific areas to create a world. In my view, village chiefs in the new situation,
3、 we must first have five basic quality. One ambition is to pioneer. Who is handsome. People only high-minded can stimulate the flow of momentum to become brave and persistent, become quiet and powerful. Township and village party leaders, within their respective jurisdictions, political stability an
4、d economic and social development issues, decisions and orientation depends to a large extent because of your. Everybody in village chiefs and the positions, both the trust of the masses, the Organizations trust, more ability to you, fully affirmed the moral and other qualities. Therefore, we must a
5、lways maintain the historical mission and social responsibility, and our ideal tree rooted in the hard work of the soil, with indomitable spirit, indomitable courage to open up a new situation of villages and towns. To have a feeling of closeness to the second. The people and country. Our business f
6、oundation in the peoples blood in the people power people. Advanced decisions of the party cadres to the feelings of the people is an eternal theme. Fan Zhong-yan, called first, and enjoy comfort about others, Zheng Banqiaos also wrote a Ya Chai lay listening to the rustling of bamboo, the suspect i
7、s suffering. Cao County officials, little my, a total turn off. Old of feudal official even has so feelings, alone we is to serving for purposes of people servant does? we more should always hold with on people of deep feelings, heart Department masses of leading visited tea, care masses of emotions
8、 thoughts complained, always insisted put masses of interests put in first, consciously from itself do up, from small do up, from masses most care, and most directly, and most reality of interests problem grabbed, real do love for people by Department, and right for people by with, and Lee for peopl
9、e by conspiracy to. Three with the fame of mind. Non-indifferent not insist your dream, without serenity not go far. Ascension to fame is morality, is the sublimation of the soul. As Township and village, be sure to maintain a normal state of mind, establish a correct viewpoint on power, position an
10、d values and Outlook, as fame is light like water, depending . 50 km, also red and like hundreds of thousands of the KMT military combat, but he went on to collect a variety of newspapers and magazines, and then race against time to pore over. As long as the study of mind, it is not necessary to com
11、e to the library, workshops, into the villages, people learned farming techniques, problem-solving methods, participation in焊条电弧焊与电弧切割设备的基本结构和工作原理图36焊机分类 焊条电弧焊所用焊机按电源的种类可分为交流弧焊机和直流弧焊机两大类。其中直流弧焊机按变流的方式不同又分为：弧焊整流器、逆变弧焊机和旋转式直流弧焊发电机(现已淘汰)等。每一类型的焊机根据原理和结构特点又可分为多种型式，具体见图36 一、交流弧焊机 (一)结构 交流弧焊机的三个类别的结构分别如图3
12、7图39所示。图37 BX1330交流弧焊机1初级绕组；2、3次级绕组；4动铁芯；5静铁芯；6接线板；7摇把图38 BX2500型(同体式)焊机结构示意图1固定铁心 2初级绕组 3次级绕组 4电抗线圈 5活动铁心图39 BX3300型(动圈式)焊机结构示意图1初级线圈 2次级线圈 3铁心 (二)工作原理 目前应用最广泛的“动铁式”交流焊机如图37所示。它是一个结构特殊的降压变压器，属于动铁芯漏磁式类型。焊机的空载电压为6070V。工作电压为30V，电流调节范围为50450A。铁芯由两侧的静铁芯5和中间的动铁芯4组成，变压器的次级绕组分成两部分，一部分紧绕在初级绕组1的外部，另一部分绕在铁芯的另
13、一侧。前一部分起建立电压的作用，后一部分相当于电感线圈。焊接时，电感线圈的感抗电压降使电焊机获得较低的工作电压，这是电焊机具有陡降外特性的原因。引弧时，电焊机能供给较高的电压和较小的电流，当电弧稳定燃烧时，电流增大，而电压急剧降低；当焊条与工件短路时，也限制了短路电流。 焊接电流调节分为粗调、细调两档。电流的细调靠移动铁芯4改变变压器的漏磁来实现。向外移动铁芯，磁阻增大，漏磁减小，则电流增大，反之，则电流减少。电流的粗调靠改变次级绕组的匝数来实现。 该电弧焊机的工作条件为应在海拔不超过1000m，周围空气温度不超过+40、空气相对湿度不超过85等条件下使用，不应在有害工业气体、水蒸汽、易燃、多
14、灰尘的场合下工作。 二、直流弧焊机 (一)结构 由于整流或直流弧焊机与直流弧焊发电机比较，因没有机械旋转部分，具有噪音小，空载损耗小、效率高、成本低和制造维护简单等优点。因此，有取代直流弧焊发电机的趋势，在这里只介绍整流式直流弧焊机。整流式直流弧焊机常用型号如ZXG300、ZXG400等。硅整流电弧焊机是利用硅半导体整流元件(二极管)将交流电变为直流电作为焊接电源。图310为硅整流电弧焊机的结构示意图。图310 硅整流电弧焊机1硅整流器组 2三相变压器 3三相磁饱和电抗器 4输出电抗器 5通风机组 (二)工作原理 工作原理见图311。接通开关K1，通风机组FM运转，风压开关KEY闭合，主接触器
15、Jc-1闭合，三相弧焊变压器B1工作。与此同时Jc-2闭合，控制变压器B2工作，磁放大器运行，硅整流器工作，输出一定的直流电压，这就是焊机的空载电压。由于没有焊接电流，磁放大器的电抗绕组FD电抗压降几乎为零，使焊机输出端具有较高的空载电压，便于引弧。当施焊时，由于有输出，形成电流，电抗绕组FD通过交流电，使其得到较大的电抗压降，并随电流的增大，电抗压降随之增大，从而得到陡降外特性。当短路时，由于短路电流很大，FD通过的交流电急增，它产生的电抗压降使工作电压几乎接近于零，这就限制了短路电流。图311 ZXG300型硅整流电焊机电气原理图 改变控制回路磁盘电阻R10，使磁放大器控制绕组FK中直流电
16、发生变化，铁芯中的磁通就相应发生变化，从而改变了磁放大器交流绕组FD的电流。为减少网路电压波动对焊接的影响，在控制回路中采用了铁磁谐振式稳压器，以保证激磁电流的稳定，减少对焊接电流的影响。 按动K2，通风机组FM停止工作，风压开关KEY开启，主接触器Jc-1断开，主回路断电。同时Jc-2断开，控制回路断电，焊机全部停止工作。 焊接电流的调节依靠面板上的电流调节控制器，来改变磁放大器控制或线圈中直流电大小使铁芯中的磁通发生相应变化，从而调整了焊接电流的大小。热将接线板烧毁或使由焊钳过热而无法工作。 三、负载持续率 焊接设备铭牌中都标有负载持续率。负载持续率是用来表示焊接设备工作状态的参数，它是在
17、选定的工作时间周期内允许焊接设备连续负载的时间。 众所周知，焊接设备工作时会发热，温升过高会把焊接设备的线包绝缘烧毁(一般焊接设备的温度不得超过6080)。温升与焊接电流大小有关，同时也与焊机使用状态有关，连续运转与断续使用时温升情况不一样。 负载持续率计算方法如下： 标准规定：500A以下的焊接设备选定的工作时间周期为5分钟。计算时，每个5分钟内测出电弧燃烧时间，代入式中即得出焊机负载持续率。 表33和表34给出了交流弧焊机BX3一300的负载持续率和硅整流弧焊机ZXG一300的负载持续率及相应的工作电流。表33 BX3300交流弧焊机负载持续率负载持续率()焊接电流(A)100602303
18、00表34 ZXG300硅整流弧焊机负载持续率负载持续率()焊接电流(A)10060232300 四、焊机的外特性 在规定范围内，焊机稳态输出电流和输出电压的关系称为焊机的外特性。焊机的外特性如图312所示。 焊机外特性有三种形式：即下降特性(陡降、缓降)、平特性和上升特性。由于熔滴过渡和热惯性以及操作等原因，焊接时电弧长度总是在不断的变化，因而电弧电压和焊接电流也在不断地变化。为保证焊接质量稳定，总希望焊接过程中焊接电流变动越小越好。从图313可以看出，具有陡降外特性的焊机和缓降外特性的焊机，当焊接电流发生相应的变化值I时，陡降外特性曲线引起的电压变化值U2大于缓降外特性曲线引起的电压变化值
19、U1。换句话说，对于相同的弧长变化，陡降外特性焊机所引起的电流变化要比缓降外特性焊机所引起的焊接电流变化小得多。焊条电弧焊过程中，弧长变化是经常发生的，为了保证焊接电流稳定，显然要求焊机具有陡降的外特性。图312 焊机外特性曲线1陡降外特性曲线 2缓降外特性曲线 3上升特性曲线 4乎特性曲线图313 两种不同下降程度的外特性曲线1缓降外特性曲线 2陡降外特性曲线 五、焊条电弧焊辅助设备和工具 焊条电弧焊辅助设备和工具包括电焊钳、焊接电缆、面罩及其它防护用具。 (一)电焊钳 电焊钳是夹持焊条并传导焊接电流的操作器具。对电焊钳的要求是：在任何斜度都能夹紧焊条；具有可靠的绝缘和良好的隔热性能；电缆的
20、橡胶包皮应伸入到钳柄内部，使导体不外露，起到屏护作用；轻便、易于操作。电焊钳的规格和主要技术数据见表35。表35 电焊钳的规格和主要技术数据规格(A)额定值适用焊条直径(mm)耐电压性能(Vmin)能连接的最大电缆截面(mm2)负载持续率()工作电压(V)工作电流(A)50060405004.08.010009530060323002.55.910005010060261602.04.0100035 (二)焊接电缆 焊条电弧焊在工作中除焊接设备外，还必须有焊接电缆。焊接电缆应采用橡皮绝缘多股软电缆，根据焊机的容量，选取适当的电缆截面，选取时可参考表36。如果焊机距焊接工作点较远，需要较长电缆时
21、，应当加大电缆截面积使在焊接电缆上的电压降不超过4V，以保证引弧容易及电弧燃烧稳定。不允许用扁铁搭接或其它办法来代替连接焊接的电缆，以免因接触不良而使回路上的压降过大，造成引弧困难和焊接电弧的不稳定。表36 焊接电缆选用表最大焊接电流(A)200300450600焊接电缆截面积(mm2)25507095 焊机和焊接手柄与焊接电缆的接头必须拧紧，表面应保持清洁，以保证其良好的导电性能。不良的接触会损耗电能，还会导致焊机过热将接线板烧毁或使电焊钳过热而无法工作。 (三)面罩及其它防护用具 面罩的主要作用是保护电焊工的眼睛和面部不受电弧光的辐射和灼伤，面罩分手持式和头盔式两种。面罩上的护目玻璃起到减
22、弱电弧光并过滤红外线、紫外线的作用。护目玻璃有不同色号、目前以黑绿色的为多，应根据电焊工的年龄和视力情况尽量选择颜色较深的护目玻璃以保护视力。护目玻璃外还加有相同尺寸的一般玻璃，以防金属飞溅沾污护目玻璃。焊工用护目遮光镜片的选用可按表118进行。 其它防护用品有电焊工在工作时需佩带的专用电焊手套和护脚，以及清渣时应戴的平光眼镜。 六、交流弧焊机与直流弧焊机的比较 交流弧焊机的主要优点是成本低、制造维护简单，噪声较小；缺点是不能适应碱性焊条，且焊接电压、电流容易受到电网波动的干扰。直流弧焊机的优点是电弧稳定，焊条适应性强；缺点是成本较高，制造维修较复杂，重量较重。但由于优点明显，直流弧焊机是大有
23、前途的电焊机。表37列出了两类焊机的性能比较。表37 两类焊机比较项 目直流弧焊机交流弧焊机电弧稳定性高低极性可换性有无构造与维修稍复杂简 单工作时噪声很 少较 小供电方式一般为三相供电一般为单相供电触电危险性较 小较 大功率因数较 高较 低耗能指数小较 大成本较 高低重 量较 轻轻conferences, learned superiors policies; reports, you can learn to deal with problems, art, just wanted to learn, to learn at any time. To continuously expand
24、 the scope of the study. The complexity and comprehensiveness of our work, decided to not only do we want to be professionals, or if generalists, to dabble in different areas of knowledge. Mastery of knowledge not only to have knowledge to rational analysis. This on requirements we, not only to lear
25、ning national of route, and approach, and policy, also to learning national of legal, and regulations; not only to with political theory armed mind, also to with economic theory guide work; not only to read history, also to read history; not only to absorption SM of mirror, also to gets is of road;
26、not only to from local learn, also to to outside learn; not only to to books learn, also to field study learn. Therefore, I would encourage you, and more to the outside world when I have time to take a look at, take a stroll, outside developments, learn other peoples development approach, and then c
27、ome back to guide our work. Second, we must think. Learning without thought to overshadow, thinking without learning is perilous. We want to foster the character of advancing with the times, forge ahead, often reflect themselves in adapting to the new situation on whether there are delays, have anyt
28、hing to fear in the reform and innovation, whether in terms of accelerating the development of a relaxation, keep promising State of mind. In order to do investigations, investigations is the road to heaven, God disposes of the base. To wants to real heard truth, and justice to truth, and get truth,
29、 received effectiveness, on must in-depth actual, and outreach, and in-depth masses, worship masses for Division, and masses heart, with masses with discussion everyone care of problem, listening they of calls, understand they of mood, feel they of suffering, summary they of experience, concentrated
30、 they of wisdom, especially on masses most hope, and most urgent, and most worries, and most complained of hot, and difficulties and focus problem, more to active research, caught not put. Dare to innovate, in our work, often remain the old way doesnt work, the new approach would not situation, the
31、reason, the key is that many people know that copying other peoples ideas, mechanically, using someone elses old ways. To change this predicament, requires us to break the shackles of traditional concepts to overcome conservative, conformist, good at finding new problems and to accept new things, su
32、mmarize new experience, new ideas, developing new programmes and Maverick, a new approach to solve problems, speed up development. Especially in implement superior policy spirit of process in the, both implementation, and cannot mechanically, to to extraordinary of courage and develop enterprising of spirit, put flexibility and principle combined up, put superior of spirit and local reality combined up, Yong conspiracy to breakthrough of policy, and exercise innovation of lift, developed out development works of, and grass-roots welcomes of
