nl焊條電弧焊與電弧切割設備的基本結構和工作原理

1、rapid development of the market economy environment to explore public servants duty consumption monetization reform has provided a good foundation. the socialization of rear service work has been launched, and rapid progress in some places and departments, duty consumption monetization of carrier an

2、d approach to management has been resolved. third, in recent years, exploring the monetization of duty consumption has made some progress, have gained some experience and can provide reference to the comprehensive reform of the system of public servants duty consumption further. implementing an hone

3、st canteen, standardize official entertaining management; enhancing the telecommunication expense management; elimination of county travel and countryside subsidies; research village officials capitalization management of corporate spending, and so on. finally, group .18 session to be held in beijin

4、g from november 9, 2013 to 12th. 35 years ago blew the third plenary session of the reform and opening up in the spring breeze, changed, affect the world; today, 35 years later, in the eyes of the nation and the world expect, again to reform mark china, ushered in the 18 session. xi general secretar

5、y pointed out that chinas reform has entered a crucial period and the sham shui po district, must be based on greater political courage and wisdom, lose no time in deepening reform in important fields. dares to crack a hard nut, dares to question the rapids, which dares to break the barrier of ideas

6、, and dare to benefit cure barriers. deepening reform and opening up is on schedule to achieve institutional safeguards of the moderately well-off. under the five in one the general layout of socialist modernization requirements, 18 session of the decision was a five in one and the improvement of ov

7、erall scheme of reform, will promote an integrated and coordinated economic, political, cultural, social and ecological civilization construction of the five reforms and the partys construction in the area of institutional reform. the five in one programme is to achieve a comprehensive reform of ins

8、titutional guarantees for objectives of build a well-off society, the smooth progress of the construction of a well-off society and reform the objectives of the programme. one, holding time and place importance on november 9, 2013 to the 18 session of the 12th beijing since 1978, 35, have been 7 ple

9、nary session, each time on major issues of political and economic life of the country has made important deployment. in accordance with prc political practice, often at every session of the cpc central committee in a plenary session was held immediately after the partys congress, on the theme person

10、nel, discussing election centrals top leaders, such as the election of the standing committee of the political bureau, through the central committee members, decisions, such as members of the central military commission. the second plenary session, is held in two sessions before the general election

11、, mainly to discuss a new state personnel issues. but by the third焊條電弧焊與電弧切割設備的基本結構和工作原理圖36焊機分類 焊條電弧焊所用焊機按電源的種類可分為交流弧焊機和直流弧焊機兩大類。其中直流弧焊機按變流的方式不同又分為：弧焊整流器、逆變弧焊機和旋轉式直流弧焊發(fā)電機(現已淘汰)等。每一類型的焊機根據原理和結構特點又可分為多種型式，具體見圖36 一、交流弧焊機 (一)結構 交流弧焊機的三個類別的結構分別如圖37圖39所示。圖37 bx1330交流弧焊機1初級繞組；2、3次級繞組；4動鐵芯；5靜鐵芯；6接線板；7搖把圖38

12、bx2500型(同體式)焊機結構示意圖1固定鐵心 2初級繞組 3次級繞組 4電抗線圈 5活動鐵心圖39 bx3300型(動圈式)焊機結構示意圖1初級線圈 2次級線圈 3鐵心 (二)工作原理 目前應用最廣泛的“動鐵式”交流焊機如圖37所示。它是一個結構特殊的降壓變壓器，屬于動鐵芯漏磁式類型。焊機的空載電壓為6070v。工作電壓為30v，電流調節(jié)范圍為50450a。鐵芯由兩側的靜鐵芯5和中間的動鐵芯4組成，變壓器的次級繞組分成兩部分，一部分緊繞在初級繞組1的外部，另一部分繞在鐵芯的另一側。前一部分起建立電壓的作用，后一部分相當于電感線圈。焊接時，電感線圈的感抗電壓降使電焊機獲得較低的工作電壓，這是

13、電焊機具有陡降外特性的原因。引弧時，電焊機能供給較高的電壓和較小的電流，當電弧穩(wěn)定燃燒時，電流增大，而電壓急劇降低；當焊條與工件短路時，也限制了短路電流。 焊接電流調節(jié)分為粗調、細調兩檔。電流的細調靠移動鐵芯4改變變壓器的漏磁來實現。向外移動鐵芯，磁阻增大，漏磁減小，則電流增大，反之，則電流減少。電流的粗調靠改變次級繞組的匝數來實現。 該電弧焊機的工作條件為應在海拔不超過1000m，周圍空氣溫度不超過+40、空氣相對濕度不超過85等條件下使用，不應在有害工業(yè)氣體、水蒸汽、易燃、多灰塵的場合下工作。 二、直流弧焊機 (一)結構 由于整流或直流弧焊機與直流弧焊發(fā)電機比較，因沒有機械旋轉部分，具有噪

14、音小，空載損耗小、效率高、成本低和制造維護簡單等優(yōu)點。因此，有取代直流弧焊發(fā)電機的趨勢，在這里只介紹整流式直流弧焊機。整流式直流弧焊機常用型號如zxg300、zxg400等。硅整流電弧焊機是利用硅半導體整流元件(二極管)將交流電變?yōu)橹绷麟娮鳛楹附与娫?。圖310為硅整流電弧焊機的結構示意圖。圖310 硅整流電弧焊機1硅整流器組 2三相變壓器 3三相磁飽和電抗器 4輸出電抗器 5通風機組 (二)工作原理 工作原理見圖311。接通開關k1，通風機組fm運轉，風壓開關key閉合，主接觸器jc-1閉合，三相弧焊變壓器b1工作。與此同時jc-2閉合，控制變壓器b2工作，磁放大器運行，硅整流器工作，輸出一定

15、的直流電壓，這就是焊機的空載電壓。由于沒有焊接電流，磁放大器的電抗繞組fd電抗壓降幾乎為零，使焊機輸出端具有較高的空載電壓，便于引弧。當施焊時，由于有輸出，形成電流，電抗繞組fd通過交流電，使其得到較大的電抗壓降，并隨電流的增大，電抗壓降隨之增大，從而得到陡降外特性。當短路時，由于短路電流很大，fd通過的交流電急增，它產生的電抗壓降使工作電壓幾乎接近于零，這就限制了短路電流。圖311 zxg300型硅整流電焊機電氣原理圖 改變控制回路磁盤電阻r10，使磁放大器控制繞組fk中直流電發(fā)生變化，鐵芯中的磁通就相應發(fā)生變化，從而改變了磁放大器交流繞組fd的電流。為減少網路電壓波動對焊接的影響，在控制回

16、路中采用了鐵磁諧振式穩(wěn)壓器，以保證激磁電流的穩(wěn)定，減少對焊接電流的影響。 按動k2，通風機組fm停止工作，風壓開關key開啟，主接觸器jc-1斷開，主回路斷電。同時jc-2斷開，控制回路斷電，焊機全部停止工作。 焊接電流的調節(jié)依靠面板上的電流調節(jié)控制器，來改變磁放大器控制或線圈中直流電大小使鐵芯中的磁通發(fā)生相應變化，從而調整了焊接電流的大小。熱將接線板燒毀或使由焊鉗過熱而無法工作。 三、負載持續(xù)率 焊接設備銘牌中都標有負載持續(xù)率。負載持續(xù)率是用來表示焊接設備工作狀態(tài)的參數，它是在選定的工作時間周期內允許焊接設備連續(xù)負載的時間。 眾所周知，焊接設備工作時會發(fā)熱，溫升過高會把焊接設備的線包絕緣燒毀

17、(一般焊接設備的溫度不得超過6080)。溫升與焊接電流大小有關，同時也與焊機使用狀態(tài)有關，連續(xù)運轉與斷續(xù)使用時溫升情況不一樣。 負載持續(xù)率計算方法如下： 標準規(guī)定：500a以下的焊接設備選定的工作時間周期為5分鐘。計算時，每個5分鐘內測出電弧燃燒時間，代入式中即得出焊機負載持續(xù)率。 表33和表34給出了交流弧焊機bx3一300的負載持續(xù)率和硅整流弧焊機zxg一300的負載持續(xù)率及相應的工作電流。表33 bx3300交流弧焊機負載持續(xù)率負載持續(xù)率()焊接電流(a)10060230300表34 zxg300硅整流弧焊機負載持續(xù)率負載持續(xù)率()焊接電流(a)10060232300 四、焊機的外特性

18、在規(guī)定范圍內，焊機穩(wěn)態(tài)輸出電流和輸出電壓的關系稱為焊機的外特性。焊機的外特性如圖312所示。 焊機外特性有三種形式：即下降特性(陡降、緩降)、平特性和上升特性。由于熔滴過渡和熱慣性以及操作等原因，焊接時電弧長度總是在不斷的變化，因而電弧電壓和焊接電流也在不斷地變化。為保證焊接質量穩(wěn)定，總希望焊接過程中焊接電流變動越小越好。從圖313可以看出，具有陡降外特性的焊機和緩降外特性的焊機，當焊接電流發(fā)生相應的變化值i時，陡降外特性曲線引起的電壓變化值u2大于緩降外特性曲線引起的電壓變化值u1。換句話說，對于相同的弧長變化，陡降外特性焊機所引起的電流變化要比緩降外特性焊機所引起的焊接電流變化小得多。焊條

19、電弧焊過程中，弧長變化是經常發(fā)生的，為了保證焊接電流穩(wěn)定，顯然要求焊機具有陡降的外特性。圖312 焊機外特性曲線1陡降外特性曲線 2緩降外特性曲線 3上升特性曲線 4乎特性曲線圖313 兩種不同下降程度的外特性曲線1緩降外特性曲線 2陡降外特性曲線 五、焊條電弧焊輔助設備和工具 焊條電弧焊輔助設備和工具包括電焊鉗、焊接電纜、面罩及其它防護用具。 (一)電焊鉗 電焊鉗是夾持焊條并傳導焊接電流的操作器具。對電焊鉗的要求是：在任何斜度都能夾緊焊條；具有可靠的絕緣和良好的隔熱性能；電纜的橡膠包皮應伸入到鉗柄內部，使導體不外露，起到屏護作用；輕便、易于操作。電焊鉗的規(guī)格和主要技術數據見表35。表35 電

20、焊鉗的規(guī)格和主要技術數據規(guī)格(a)額定值適用焊條直徑(mm)耐電壓性能(vmin)能連接的最大電纜截面(mm2)負載持續(xù)率()工作電壓(v)工作電流(a)50060405004.08.010009530060323002.55.910005010060261602.04.0100035 (二)焊接電纜 焊條電弧焊在工作中除焊接設備外，還必須有焊接電纜。焊接電纜應采用橡皮絕緣多股軟電纜，根據焊機的容量，選取適當的電纜截面，選取時可參考表36。如果焊機距焊接工作點較遠，需要較長電纜時，應當加大電纜截面積使在焊接電纜上的電壓降不超過4v，以保證引弧容易及電弧燃燒穩(wěn)定。不允許用扁鐵搭接或其它辦法來代替

21、連接焊接的電纜，以免因接觸不良而使回路上的壓降過大，造成引弧困難和焊接電弧的不穩(wěn)定。表36 焊接電纜選用表最大焊接電流(a)200300450600焊接電纜截面積(mm2)25507095 焊機和焊接手柄與焊接電纜的接頭必須擰緊，表面應保持清潔，以保證其良好的導電性能。不良的接觸會損耗電能，還會導致焊機過熱將接線板燒毀或使電焊鉗過熱而無法工作。 (三)面罩及其它防護用具 面罩的主要作用是保護電焊工的眼睛和面部不受電弧光的輻射和灼傷，面罩分手持式和頭盔式兩種。面罩上的護目玻璃起到減弱電弧光并過濾紅外線、紫外線的作用。護目玻璃有不同色號、目前以黑綠色的為多，應根據電焊工的年齡和視力情況盡量選擇顏色

22、較深的護目玻璃以保護視力。護目玻璃外還加有相同尺寸的一般玻璃，以防金屬飛濺沾污護目玻璃。焊工用護目遮光鏡片的選用可按表118進行。 其它防護用品有電焊工在工作時需佩帶的專用電焊手套和護腳，以及清渣時應戴的平光眼鏡。 六、交流弧焊機與直流弧焊機的比較 交流弧焊機的主要優(yōu)點是成本低、制造維護簡單，噪聲較小；缺點是不能適應堿性焊條，且焊接電壓、電流容易受到電網波動的干擾。直流弧焊機的優(yōu)點是電弧穩(wěn)定，焊條適應性強；缺點是成本較高，制造維修較復雜，重量較重。但由于優(yōu)點明顯，直流弧焊機是大有前途的電焊機。表37列出了兩類焊機的性能比較。表37 兩類焊機比較項 目直流弧焊機交流弧焊機電弧穩(wěn)定性高低極性可換性

23、有無構造與維修稍復雜簡 單工作時噪聲很 少較 小供電方式一般為三相供電一般為單相供電觸電危險性較 小較 大功率因數較 高較 低耗能指數小較 大成本較 高低重 量較 輕輕plenary session, each session of the central committee of national institutions and personnel problems have been arranged, you can concentrate on national development and reforms. previous plenary session is often br

24、anded with a central leading collective, often by looking at the third plenum of the initiative to found the current central leadership collective governance characteristics. from the analysis of the process of economic reform in china, plenary session, 12 session, 14, 16 plenary session have progra

25、mmatic meaning, respectively, marking the four stages of chinas economic reform, and that the start-up phase of reform, reform, construction phase and perfecting the socialist market economy framework stage of socialist market economy. previous plenary session topics proposed to the third plenary se

26、ssion of taking class struggle as the key link, shifted to socialist modernization; 12 session marked the change from rural to urban, established with public ownership as the foundation of a planned commodity economy; 13 session at a time when both the old and the new system change, governance and r

27、ectify the economic order; 14 . fair and efficient and authoritative socialist judicial system, safeguard the peoples interests. legal authority to uphold the constitution, deepening the reform of administrative law enforcement, ensure that the right to exercise judicial power independently and impa

28、rtially according to law the prosecution, perfecting the running mechanism of judicial power, improve the system of judicial protection of human rights. plenary session, affairs the right to adhere to the system, and let the people authority to let the power run in the sun, is shut up in a cage of t

29、he system power policy. decision science, implementation should be constructed strong, supervise the running of powerful system, improve the system of punishing and preventing corruption, promoting political integrity, and strive to achieve cadres honest and government integrity, clean politics. to form a scientific and effective coordination of