（內容來自百度百科）點焊機按照用途分，有萬能式(通用式)、專用式;按照同時焊接的焊點數(shù)目分，有單點式、雙點式、多點式;按照導電方式分，有單側的、雙側的;按照加壓機構的傳動方式分，有腳踏式、電動機-凸輪式、氣壓式、液壓式、復合式(氣液壓合式);按照運轉的特性分，有非自動化、自動化;按照安裝的方法分，有固定式，移動式或輕便式(懸掛式);按照焊機的活動電極(普通是上電極)的移動方向分，有垂直行程(電極作直線運動)、圓弧行程;按照電能的供給方式分，有工頻焊機(采用50赫茲交流電源)、脈沖焊機(直流脈沖焊機、儲能焊機等)、變頻焊機(如低頻焊機)。

當工件和電極一定時，工件的電阻取決與它的電阻率.因此，電阻率是被焊材料的重要性能.電阻率高的金屬其導電性差(如不銹鋼)電阻率低的金屬其導電性好(如鋁合金)。因此，點焊不銹鋼時產熱易而散熱難，點焊鋁合金時產熱難而散熱易.點焊時，前者可用較小電流(幾千安培)，而后者就必須用很大電流(幾萬安培)。電阻率不僅取決與金屬種類，還與金屬的熱處理狀態(tài)、加工方式及溫度有關。
為了保證熔核尺寸和焊點強度，焊接時間與焊接電流在一定范圍內可以相互補充。為了獲得一定強度的焊點，可以采用大電流和短時間(強條件，又稱硬規(guī)范)，也可采用小電流和長時間(弱條件，也稱軟規(guī)范)。選用硬規(guī)范還是軟規(guī)范，取決于金屬的性能、厚度和所用焊機的功率。對于不同性能和厚度的金屬所需的電流和時間，都有一個上下限，使用時以此為準。
電極壓力對兩電極間總電阻R有明顯的影響，隨著電極壓力的增大，R顯著減小，而焊接電流增大的幅度卻不大，不能影響因R減小引起的產熱減少。因此，焊點強度總隨著焊接壓力增大而減小。解決的辦法是在增大焊接壓力的同時，增大焊接電流。

分類
點焊機按用途可以分成萬能式（通用式、專用式）點焊機；
按同時焊接的焊點數(shù)目分為：有單點式、雙點式、多點式；
按導電方式分為：單側的、雙側的；
按加壓機構的傳動方式分為：腳踏式、電動機-凸輪式、氣壓式、液壓式、復合式（氣液壓合式）；
按運轉的特性分為：非自動化、自動化；
按安裝的方法分為：固定式，移動式或輕便式（懸掛式）點焊機；
按焊機的活動電極（普通是上電極）的移動方向分為：垂直行程（電極作直線運動）、圓弧行程。
工作原理編輯
點焊的工藝過程為開通冷卻水;將焊件表面清理干凈，裝配準確后，送入上、下電極之間，施加壓力，使其接觸良好;通電使兩工件接觸表面受熱，局部熔化，形成熔核;斷電后保持壓力，使熔核在壓力下冷卻凝固 　形成焊點;去除壓力，取出工件。焊接電流、電極壓力、通電時間及電極工作表面尺寸等點焊工藝參數(shù)對焊接質量有重大影響。
點焊機利用正負兩極在瞬間短路時產生的高溫電弧來熔化電極間的被焊材料，來達到使它們結合的目的。點焊機的結構十分簡單，說白了就是一個大功率的變壓器，將220V交流電變?yōu)榈碗妷海箅娏鞯碾娫矗梢允侵绷鞯囊部梢允墙涣鞯摹ｋ姾缸儔浩饔凶陨淼奶攸c，就是具有電壓急劇下降的特性。
在焊條引燃后電壓下降，電焊機的工作電壓的調節(jié)，除了一次的220/380電壓變換，二次線圈也有抽頭變換電壓，同時還有用鐵芯來調節(jié)的，可調鐵芯。電焊機一般是一個大功率的變壓器，系利用電感的原理做成的。電感量在接通和斷開時會產生巨大的電壓變化，利用正負兩極在瞬間短路時產生的高壓電弧來熔化電焊條上的焊料。來達到使它們結合的目的。
點焊是焊件裝配接接頭，并壓緊在兩電極之間，利用電阻熱熔化母材金屬，形成焊點的電阻焊方法。點焊多 　用于薄板的連接，如飛機蒙皮、航空發(fā)動機的火煙筒、汽車駕駛室外殼等。點焊機焊接變壓器是點焊電器，它的次級只有一圈回路。上、下電極與電極臂既用于傳導焊接電流，又用于傳遞動力。冷卻水路通過變壓器、電極等部分，以免發(fā)熱焊接時，應先通冷卻水，然后接通電源開關。電極的質量直接影響焊接過程、焊接質量和生產率。電極材料常用紫銅、鎘青銅、鉻青銅等制成;電極的形狀多種多樣，主要根據(jù)焊件形狀確定。安裝電極時，要注意上、下電極表面保持平行;電極平面要保持清潔，常用砂布或銼刀修整。焊接循環(huán)點焊和凸焊的焊接循環(huán)由四個基本階段(點焊過程)：
(1)預壓階段——電極下降到電流接通階段，確保電極壓緊工件，使工件間有適當壓力。
(2)焊接時間——焊接電流通過工件，產熱形成熔核。
(3)維持時間——切斷焊接電流，電極壓力繼續(xù)維持至熔核凝固到足夠強度。
(4)休止時間——電極開始提起到電極再次開始下降，開始下一個焊接循環(huán)。
為了改善焊接接頭的性能，有時需要將下列各項中的一個或多個加于基本循環(huán)：
(1)加大預壓力以消除厚工件之間的間隙，使之緊密貼合。
(2)用預熱脈沖提高金屬的塑性，使工件易于緊密貼合、防止飛濺;凸焊時這樣做可以使多個凸點在通電焊接前與平板均勻接觸，以保證各點加熱的一致。
機械使用編輯
點焊機使用方法：
1、焊接時應先調節(jié)電極桿的位置，使電極剛好壓到焊件時，電極臂保持互相平行。
2、電流調節(jié)開關級數(shù)的選擇可按焊件厚度與材質而選定。通電后電源指示燈應亮，電極壓力大小可調整彈簧壓力螺母，改變其壓縮程度而獲得。
3、在完成上述調整后，可先接通冷卻水后再接通電源準備焊接。焊接過程的程序：焊件置于兩電極之間，踩下腳踏板，并使上電極與焊件接觸并加壓，在繼續(xù)壓下腳踏板時，電源觸頭開關接通，于是變壓器開始工作次級回路通電使焊件加熱。當焊接一定時間后松開腳踏板時電極上升，借彈簧的拉力先切斷電源而后恢復原狀，單點焊接過程即告結束。
4、焊件準備及裝配：鋼焊件焊前須清除一切臟物、油污、氧化皮及鐵銹，對熱軋鋼，最好把焊接處先經(jīng)過酸洗、噴砂或用砂輪清除氧化皮。未經(jīng)清理的焊件雖能進行點焊，但是嚴重地降低電極的使用壽命，同時降低點焊的生產效率和質量。對于有薄鍍層的中低碳鋼可以直接施焊。
另外，用戶在使用時可參考下列工藝數(shù)據(jù)：
1、焊接時間：在焊接中低碳鋼時，本焊機可利用強規(guī)范焊接法(瞬時通電)或弱規(guī)范焊接法(長時通電)。在大量生產時應采用強規(guī)范焊接法，它能提高生產效率，減少電能消耗及減輕工件變形。
2、焊接電流：焊接電流決定于焊件之大小、厚度及接觸表面的情況。通常金屬導電率越高，電極壓力越大，焊接時間應越短。此時所需的電流密度也隨之增大。
3、電極壓力：電極對焊件施加壓力的目的是為了減小焊點處的接觸電阻，并保證焊點形成時所需要的壓力。
安全編輯
1.現(xiàn)場使用的，應設有防雨、防潮、防曬的機棚，并應裝設相應的消防器材。
2.焊接現(xiàn)場10m范圍內，不得堆放油類、木材、氧氣瓶、乙炔發(fā)生器等易燃、易爆物品。
3.焊接操作及配合人員必須按規(guī)定穿戴勞動防護用品。并必須采取防止觸電、高空墜落、瓦斯中毒火災等事故的安全措施。
4. 次級抽頭聯(lián)接銅板應壓緊，接線柱應有墊圈。合閘前，應詳細檢查接線螺帽、螺栓及其他部件并確認完好齊全、無松動或損壞。接線柱處均有保護罩。
5.使用前，應檢查并確認初、次級線接線正確，輸入電壓符合電焊機的銘牌規(guī)定，知道點焊機焊接電流的種類和適用范圍。接通電源后，嚴禁接觸初級線路的帶電部分。初、次級接線處必須裝有防護罩。
6.移動點焊機時，應切斷電源，不得用拖拉電纜的方法移動焊機。當焊接中突然停電時，應立即切斷電源。
7.焊接銅、鋁、鋅、錫、鉛等有色金屬時，必須在通風良好的地方進行，焊接人員應戴防毒面具或呼吸濾清器。
8.多臺點焊機集中使用時，應分接在三相電源網(wǎng)絡上，使三相負載平衡。多臺焊機的接地裝置，應分別由接地極處引接，不得串聯(lián)。
9.嚴禁在運行中的壓力管道、裝有易燃易爆物的容器和受力構件上進行焊接。
10.焊接預熱件時，應設擋板隔離預熱焊件發(fā)出的輻射熱。
安裝維護編輯
焊機必須妥善接地后方可使用,以保障人身安全。焊機使用前要用500V兆歐表測試焊機高壓側與機殼之間絕緣電阻不低于2.5兆歐方可通電。檢修時要先切斷電源，方可開箱檢查。焊機先通水后施焊，無水嚴禁工作。冷卻水應保證在0.15--0.2MPa進水壓力下供應5--30℃的工業(yè)用水。冬季焊機工作完畢后應用壓縮空氣將管路中的水吹凈以免凍裂水管。
焊機引線不宜過細過長，焊接時的電壓降不得大于初始電壓的5%，初始電壓不能偏離電源電壓的±10%。焊機操作時應戴手套、圍裙和防護眼鏡，以免火星飛出燙傷。滑動部分應保持良好潤滑，使用完后應清除金屬濺沫。新焊機開始使用24小時后應將各部件螺絲緊固一次，尤其要注意銅軟聯(lián)和電極之間聯(lián)接螺絲一定要緊固好，用完后應經(jīng)常清除電極桿和電極臂之間的氧化物，以保證良好接觸。
焊機使用時如發(fā)現(xiàn)交流接觸器吸合不實，說明電網(wǎng)電壓過低，用戶應該首先解決電源問題，電源正常后方可使用。需要指出的是，新購買的焊機半個月內如出現(xiàn)主件質量問題，可以更換新的焊機或者更換主件。焊機主機部分保修一年，長期提供維修服務。一般情況下用戶通知廠方后，根據(jù)路程遠近三到七天內服務到位。由于用戶原因而造成的焊機損壞不在保修范圍內。易損件、消耗件不在保修范圍內。
由于電極的接觸面積決定著電流密度，電極材料的電阻率和導熱性關系著熱量的產生和散失，因此，電極的形狀和材料對熔核的形成有顯著影響。隨著電極端頭的變形和磨損，接觸面積增大，焊點強度將降低。工件表面的氧化物、污垢、油和其他雜質增大了接觸電阻。過厚的氧化物層甚至會使電流不能通過。局部的導通，由于電流密度過大，則會產生飛濺和表面燒損。氧化物層的存在還會影響各個焊點加熱的不均勻性，引起焊接質量波動。因此徹底清理工件表面是保證獲得優(yōu)質接頭的必要條件。
故障排除
1、踏下腳踏板焊機不工作，電源指示燈不亮：
a.檢查電源電壓是否正常;檢查控制系統(tǒng)是否正常。
b.檢查腳踏開關觸點、交流接觸器觸點、分頭換擋開關是否接觸良好或燒損。
2、電源指示燈亮，工件壓緊不焊接：
a.檢查腳踏板行程是否到位，腳踏開關是否接觸良好。
b.檢查壓力桿彈簧螺絲是否調整適當。
3、焊接時出現(xiàn)不應有的飛濺：
a.檢查電極頭是否氧化嚴重。
b.檢查焊接工件是否嚴重銹蝕接觸不良。
c.檢查調節(jié)開關是否檔位過高。
d.檢查電極壓力是否太小，焊接程序是否正確。
4、焊點壓痕嚴重并有擠出物：
a.檢查電流是否過大。
b.檢查焊接工件是否有凹凸不平。
c.檢查電極壓力是否過大，電極頭形狀、截面是否合適。
5、焊接工件強度不足：
a.檢查電極壓力是否太小，檢查電極桿是否緊固好。
b.檢查焊接能量是否太小，焊接工件是否銹蝕嚴重，使焊點接觸不良。
c.檢查電極頭和電極桿、電極桿和電極臂之間是否氧化物過多。
d.檢查電極頭截面是否因為磨損而增大造成焊接能量減小。
e.檢查電極和銅軟聯(lián)和結合面是否嚴重氧化。
6、焊接時交流接觸器響聲異常：
a.檢查交流接觸器進線電壓在焊接時是否低于自身釋放電壓300伏。
b.檢查電源引線是否過細過長，造成線路壓降太大。
c.檢查網(wǎng)路電壓是否太低，不能正常工作。
d.檢查主變壓器是否有短路，造成電流太大。
7、焊機出現(xiàn)過熱現(xiàn)象：
a.檢查電極座與機體之間絕緣電阻是否不良，造成局部短路。
b.檢查進水壓力、水流量、供水溫度是否合適，檢查水路系統(tǒng)是否有污物堵塞，造成因為冷卻不好使電極臂、電極桿、電極頭過熱。
c.檢查銅軟聯(lián)和電極臂，電極桿和電極頭接觸面是否氧化嚴重，造成接觸電阻增加發(fā)熱嚴重。
d.檢查電極頭截面是否因磨損增加過多，使焊機過載而發(fā)熱。
e.檢查焊接厚度、負載持續(xù)率是否超標，使焊機過載而發(fā)熱 [1] 
優(yōu)缺點
電阻焊具有下列優(yōu)點：
1、熔核形成時，始終被塑性環(huán)包圍，熔化金屬與空氣隔絕，冶金過程簡單。
2、加熱時間短、熱量集中，故熱影響區(qū)小，變形與應力也小，通常在焊后不必安排矯正和熱處理工序。
3、不需要焊條、焊絲等填充金屬，以及氧、乙炔、氬等焊接材料，焊接成本低。
4、操作簡單，易于實現(xiàn)機械化和自動化，改善了勞動條件。
5、生產率高，且無噪聲及有害氣體，在大批量生產中，可以和其它制造工序一起編到組裝線上，但閃光對焊因有火花噴濺，需要隔離。
電阻焊具有下列缺點：
1、缺乏可靠的無損檢測方法，焊接質量只能靠工藝試樣和焊件的破壞性試驗來檢查，以及靠各種監(jiān)控技術來保證。

2、點、縫焊的搭接接頭不僅增加了構件的重量，且因在兩板間熔核周圍形成夾角，致使接頭的抗拉強度和疲勞強度均較低。

The spot welding machine is divided into universal type (general type) and special type according to the purpose; according to the number of welding points welded at the same time, there are single-point type, double-point type, multi-point type; according to the conductive mode, there are single-side, Double-sided; according to the transmission method of the pressurizing mechanism, there are foot type, motor-cam type, pneumatic type, hydraulic type, compound type (pneumatic hydraulic combined type); according to the characteristics of operation, there are non-automatic and automated; according to The installation method is divided into fixed, mobile or portable (hanging type); according to the moving direction of the movable electrode (usually the upper electrode) of the welding machine, there are vertical stroke (the electrode moves linearly) and circular stroke; According to the power supply method, there are industrial frequency welding machine (using 50 Hz AC power supply), pulse welding machine (DC pulse welding machine, energy storage welding machine, etc.), frequency conversion welding machine (such as low frequency welding machine).
When the workpiece and electrode are fixed, the resistance of the workpiece depends on its resistivity. Therefore, the resistivity is an important property of the material to be welded. The metal with high resistivity has poor conductivity (such as stainless steel) and the metal with low resistivity has good conductivity (Such as aluminum alloy). Therefore, when spot welding stainless steel, it is easy to generate heat and difficult to dissipate heat. When spot welding aluminum alloy, it is difficult to generate heat and easy to dissipate heat. When spot welding, the former can use a smaller current (thousands of amperes), while the latter must use a large current (several Million amps). The resistivity depends not only on the type of metal, but also on the heat treatment state, processing method and temperature of the metal.
In order to ensure the nugget size and the strength of the welding spot, the welding time and welding current can complement each other within a certain range. In order to obtain a certain strength of the solder joint, a large current and a short time (strong conditions, also known as hard codes), or a small current and a long time (weak conditions, also known as soft codes) can be used. The choice of hard or soft specifications depends on the performance, thickness and power of the welding machine used. There are upper and lower limits for the current and time required for metals of different properties and thicknesses, which shall prevail when used.
The electrode pressure has a significant effect on the total resistance R between the two electrodes. With the increase of the electrode pressure, R decreases significantly, but the increase in welding current is not large, and it cannot affect the reduction in heat production caused by the decrease in R. Therefore, the strength of the solder joint always decreases as the welding pressure increases. The solution is to increase the welding current while increasing the welding pressure.

classification
The spot welding machine can be divided into universal (universal, special) spot welding machines according to the purpose;
According to the number of welding points welded simultaneously, it is divided into: single point type, double point type, multi point type;
According to the conductive method, it is divided into: single-sided and double-sided;
According to the transmission method of the pressurizing mechanism, it is divided into: foot pedal, motor-cam type, pneumatic type, hydraulic type, compound type (pneumatic hydraulic type);
According to the characteristics of operation: non-automated and automated;
According to the installation method, it is divided into: fixed, mobile or portable (hanging) spot welding machine;
According to the moving direction of the movable electrode (usually the upper electrode) of the welding machine, it is divided into: vertical stroke (the electrode moves linearly) and circular stroke.
How it works
The process of spot welding is to turn on the cooling water; clean the surface of the weldment, after the assembly is accurate, send it between the upper and lower electrodes, and apply pressure to make the contact good; energization makes the contact surface of the two workpieces heated and partially melted to form Nugget; maintain pressure after power off, so that the nugget cools and solidifies under pressure to form a solder joint; remove the pressure and take out the workpiece. Spot welding process parameters such as welding current, electrode pressure, energizing time, and electrode working surface size have a significant impact on welding quality.
The spot welding machine uses the high temperature arc generated by the positive and negative poles during an instant short circuit to melt the welded material between the electrodes to achieve the purpose of combining them. The structure of the spot welding machine is very simple. To put it bluntly, it is a high-power transformer that turns 220V AC into a low voltage, high-current power supply, which can be DC or AC. The welding transformer has its own characteristics, that is, it has the characteristics of a sharp drop in voltage.
After the electrode is ignited, the voltage drops, the adjustment of the working voltage of the welding machine, in addition to the primary 220/380 voltage conversion, the secondary coil also has a tap to change the voltage, and there is also an iron core to adjust the adjustable iron core. The welding machine is generally a high-power transformer, which is made using the principle of inductance. The inductance will produce a huge voltage change when it is turned on and off. The high voltage arc generated by the positive and negative poles during an instantaneous short circuit is used to melt the solder on the electrode. To achieve the purpose of combining them.
Spot welding is a resistance welding method in which a weldment is assembled with joints, pressed between two electrodes, and the base metal is melted by resistance heat to form a welding spot. Spot welding is more used for the connection of thin plates, such as aircraft skins, fire pipes of aircraft engines, car cabin shells, etc. The welding transformer of the spot welding machine is a spot welding appliance, and its secondary has only one loop. The upper and lower electrodes and electrode arms are used to conduct welding current and transmit power. The cooling water path passes through transformers, electrodes and other parts to avoid heating and welding. The cooling water should be passed before the power switch is turned on. The quality of the electrode directly affects the welding process, welding quality and productivity. Electrode materials are commonly made of copper, cadmium bronze, chrome bronze, etc .; electrode shapes are diverse, mainly determined by the shape of the weldment. When installing the electrode, pay attention to keeping the upper and lower electrode surfaces parallel; the electrode plane should be kept clean, and usually trimmed with emery cloth or file. Welding cycle The welding cycle of spot welding and projection welding consists of four basic stages (spot welding process):
(1) Pre-compression stage-the electrode is lowered to the stage where the current is turned on, to ensure that the electrode is pressed against the workpiece, so that there is proper pressure between the workpieces.
(2) Welding time-Welding current passes through the workpiece and generates heat to form a nugget.
(3) Maintenance time—cut off the welding current, and the electrode pressure continues to be maintained until the nugget solidifies to a sufficient strength.
(4) Rest time-the electrode starts to lift up and the electrode starts to fall again, and the next welding cycle begins.
In order to improve the performance of welded joints, it is sometimes necessary to add one or more of the following to the basic cycle:
(1) Increase the preload to eliminate gaps between thick workpieces and make them fit snugly.
(2) Use preheating pulse to improve the plasticity of the metal, make the workpiece easy to fit tightly, and prevent spatter; doing this during convex welding can make multiple bumps evenly contact with the flat plate before welding to ensure the uniform heating of each point.
Mechanical use edit
How to use spot welding machine:
1. The position of the electrode rod should be adjusted during welding so that the electrode arms remain parallel to each other when the electrode is just pressed against the weldment.
2. The selection of current adjustment switch stages can be selected according to the thickness and material of the weldment. After power on, the power indicator light should be on, and the electrode pressure can be adjusted by adjusting the spring pressure nut and changing its compression degree.
3. After completing the above adjustments, you can turn on the cooling water first and then turn on the power to prepare for welding. Procedure of the welding process: the weldment is placed between the two electrodes, the foot pedal is pressed, and the upper electrode is brought into contact with the weldment and pressurized. When the foot pedal is continuously pressed, the power contact switch is turned on, and the transformer starts to work The circuit is energized to heat the weldment. When the foot pedal is released after welding for a certain period of time, the electrode rises. The power of the spring is first cut off and then restored to the original state. The single-point welding process is ended.
4. Weldment preparation and assembly: Steel weldments must be cleaned of all dirt, oil, scale and rust before welding. For hot-rolled steel, it is best to pick the welded area first by pickling, sandblasting or using a grinding wheel to remove scale. Although uncleaned weldments can be spot welded, the service life of the electrode is severely reduced, and the production efficiency and quality of spot welds are also reduced. For medium and low carbon steels with thin coatings can be directly welded.
In addition, users can refer to the following process data when using:
1. Welding time: When welding medium and low carbon steel, this welding machine can use the strong specification welding method (instantaneous power-on) or the weak specification welding method (long-term power-on). The strong standard welding method should be used in mass production, which can improve production efficiency, reduce power consumption and reduce workpiece deformation.
2. Welding current: The welding current depends on the size, thickness and contact surface of the weldment. Generally, the higher the metal conductivity, the greater the electrode pressure, and the shorter the welding time. The current density required at this time also increases.
3. Electrode pressure: The purpose of the electrode to apply pressure to the weldment is to reduce the contact resistance at the welding point and ensure the pressure required when the welding point is formed.
Security editor
1. For the on-site use, there should be a rainproof, moisture-proof and sun-proof shed, and corresponding fire-fighting equipment should be installed.
2. Within 10m of the welding site, flammable and explosive materials such as oil, wood, oxygen cylinder, and acetylene generator shall not be stacked.
3. Welding operations and cooperating personnel must wear labor protection equipment as required. Safety measures must be taken to prevent accidents such as electric shock, falling from high altitude, and gas poisoning.
4. The copper plate connected to the secondary tap should be tight, and the terminal should have a gasket. Before closing, the wiring nuts, bolts and other parts should be checked in detail and confirmed to be intact and complete, without looseness or damage. There are protective covers at the terminals.
5. Before use, you should check and confirm that the wiring of the primary and secondary wires is correct, the input voltage meets the nameplate requirements of the electric welding machine, and know the type and applicable range of the welding current of the spot welding machine. After connecting the power supply, it is strictly forbidden to touch the live part of the primary line. The primary and secondary wiring must be equipped with protective covers.
6. When moving the spot welding machine, the power supply should be cut off, and the welding machine should not be moved by pulling the cable. When there is a sudden power failure during welding, the power should be cut off immediately.
7. When welding non-ferrous metals such as copper, aluminum, zinc, tin, lead, etc., it must be done in a well-ventilated place, and the welding personnel should wear gas masks or breathing filters.
8. When multiple spot welders are used together, they should be tapped on the three-phase power network to balance the three-phase load. The grounding devices of multiple welding machines shall be connected by the grounding poles respectively, and shall not be connected in series.
9. It is strictly forbidden to weld on the pressure pipes in operation, containers with flammable and explosive materials and stressed components.
10. When welding preheated parts, baffles should be set up to isolate the radiant heat from the preheated welded parts.
Installation and maintenance
The welding machine must be properly grounded before use to ensure personal safety. Before using the welding machine, use a 500V megohmmeter to test that the insulation resistance between the high-voltage side of the welding machine and the casing is not less than 2.5 megohms before it can be powered. The power supply must be cut off during inspection before unpacking and checking. Welding machine is first to pass water and then welding, work is strictly prohibited without water. The cooling water should be guaranteed to supply industrial water at 5--30 ° C at an inlet pressure of 0.15-0.2MPa. After the welding machine is completed in winter, compressed air is used to blow the water in the pipeline to avoid freezing and cracking of the water pipe.
The welding machine leads should not be too thin or too long, the voltage drop during welding should not be greater than 5% of the initial voltage, and the initial voltage should not deviate from ± 10% of the power supply voltage. Gloves, aprons and protective glasses should be worn when the welding machine is in operation to avoid flying sparks from the sparks. The sliding part should be kept well lubricated, and metal splash should be removed after use. After using the new welding machine for 24 hours, the screws of each part should be tightened once, especially pay attention to the connection screws between the copper flexible joint and the electrode. To ensure good contact.
When the welding machine is used, if the AC contactor is found to be inadequate, it means that the grid voltage is too low. The user should first solve the power supply problem and use it after the power supply is normal. It should be pointed out that if the quality problem of the main parts occurs within half a month of the newly purchased welding machine, the new welding machine or the main parts can be replaced. The main part of the welding machine is guaranteed for one year and provides long-term maintenance services. Under normal circumstances, after the user informs the factory, the service is in place within three to seven days according to the distance. Damage to the welding machine due to user reasons is not covered by the warranty. The wearing parts and consumables are not covered by the warranty.
Since the contact area of the electrode determines the current density, the resistivity and thermal conductivity of the electrode material are related to the generation and loss of heat. Therefore, the shape and material of the electrode have a significant effect on the formation of the nugget. As the electrode tip deforms and wears, the contact area increases and the strength of the solder joint will decrease. Oxides, dirt, oil and other impurities on the surface of the workpiece increase the contact resistance. An oxide layer that is too thick can even prevent current from passing through. Local conduction, due to excessive current density, will produce splashes and surface burns. The existence of the oxide layer will also affect the unevenness of heating of each solder joint, causing welding quality fluctuations. Therefore, thoroughly cleaning the surface of the workpiece is a necessary condition to ensure that high-quality joints are obtained.
Troubleshooting
1. The welding machine does not work when the pedal is depressed, and the power indicator does not light:
a. Check whether the power supply voltage is normal; check whether the control system is normal.
b. Check whether the contact of the foot switch, the contact of the AC contactor and the split shift switch are in good contact or burned.
2. The power indicator light is on, the workpiece is not compressed and welded:
a. Check if the foot pedal travel is in place and the foot switch is in good contact.
b. Check whether the pressure rod spring screw is adjusted properly.
3. Unexpected spatter during welding:
a. Check whether the electrode head is seriously oxidized.
b. Check whether the welding workpiece is badly corroded and has poor contact.
c. Check whether the adjustment switch is too high.
d. Check whether the electrode pressure is too low and the welding procedure is correct.
4. The welding spot has serious indentation and extrudates:
a. Check if the current is too large.
b. Check whether the welding workpiece is uneven.
c. Check whether the electrode pressure is too large and the shape and cross section of the electrode head are appropriate.
5. Insufficient strength of welding workpiece:
a. Check whether the electrode pressure is too low, and check whether the electrode rod is tight.
b. Check whether the welding energy is too small, whether the welding workpiece is severely corroded, so that the welding point is poorly contacted.
c. Check if there is too much oxide between the electrode tip and electrode rod, electrode rod and electrode arm.
d. Check whether the cross section of the electrode head is increased due to wear and the welding energy is reduced.
e. Check whether the electrode and copper soft-coupling and bonding surface are severely oxidized.
6. Abnormal noise of AC contactor during welding:
a. Check whether the incoming voltage of the AC contactor is 300V lower than the self-release voltage during welding.
b. Check whether the power lead is too thin and too long, causing the line voltage drop too large.
c. Check if the network voltage is too low to work properly.
d. Check whether the main transformer has a short circuit, causing too much current.
7. Welding machine overheating phenomenon:
a. Check whether the insulation resistance between the electrode holder and the body is bad, causing a local short circuit.
b. Check whether the inlet water pressure, water flow rate, and water supply temperature are appropriate, and check whether the waterway system is blocked by dirt, causing the electrode arm, electrode rod, and electrode head to overheat due to poor cooling.
c. Check if the copper flexible coupling and electrode arm, electrode rod and electrode tip contact surface are seriously oxidized, causing contact resistance to increase and generate heat.
d. Check if the electrode head section is excessively worn due to wear, which overloads the welder and generates heat.
e. Check whether the welding thickness and load continuity rate exceed the standard, causing the welder to overload and heat up [1]
Pros and cons
Resistance welding has the following advantages:
1. When the nugget is formed, it is always surrounded by a plastic ring, the molten metal is isolated from the air, and the metallurgical process is simple.
2. The heating time is short and the heat is concentrated, so the heat affected zone is small, and the deformation and stress are also small. It is usually not necessary to arrange correction and heat treatment processes after welding.
3. No filler metals such as welding rods and welding wires, and welding materials such as oxygen, acetylene, argon, etc. are needed, and the welding cost is low.
4. Simple operation, easy to realize mechanization and automation, and improve working conditions.
5. High productivity, no noise and harmful gas. In mass production, it can be assembled on the assembly line together with other manufacturing processes, but flash butt welding needs to be isolated due to sparks and splashes.
Resistance welding has the following disadvantages:
1. Lack of reliable non-destructive testing methods, welding quality can only be checked by destructive testing of process samples and weldments, and by various monitoring techniques.
2. The lap joints of spot and seam welds not only increase the weight of the component, but also form an angle around the nugget between the two plates, resulting in a lower tensile strength and fatigue strength of the joint.