點(diǎn)焊機(jī)采用雙面雙點(diǎn)過(guò)電流焊接原理，兩個(gè)電極對(duì)神器加壓，使兩層金屬在兩個(gè)電極的壓力下形成某些壓力接觸電阻，和焊接電流什么時(shí)候從一個(gè)電極流到另一個(gè)電極時(shí)，在兩個(gè)接觸電阻點(diǎn)處形成瞬時(shí)熱焊接，焊接電流立即從另一個(gè)電極沿著兩個(gè)神器流到該電極，形成回路，并且不會(huì)損壞電極的內(nèi)部結(jié)構(gòu)。焊接神器。

中文名

目錄

1. 1引言

2. 2工作準(zhǔn)則

1. 3機(jī)械用途

2. 4安全性

1. 5安裝與維護(hù)

2. 6 鋼筋點(diǎn)焊

介紹

編輯

點(diǎn)焊按照用途分，有萬(wàn)能式(通用式)、專用式;按照同時(shí)焊接的焊點(diǎn)數(shù)量，有單點(diǎn)式、雙點(diǎn)式、多點(diǎn)式;按照導(dǎo)電方式分，有單側(cè)的、雙側(cè)的;按照加壓機(jī)構(gòu)的傳動(dòng)方式分，有腳踏式、電動(dòng)機(jī)-凸輪式、氣壓式、液壓式、復(fù)合式(氣液壓合式);按照運(yùn)轉(zhuǎn)的特性分，有非自動(dòng)化、自動(dòng)化;按照安裝的方法分，有固定式，移動(dòng)式或輕便式(懸掛式);按照焊機(jī)的活動(dòng)電極(普通是上電極)的移動(dòng)方向分，有垂直行程(電極作直線運(yùn)動(dòng))、圓弧行程;按照電能的供給方式分，有工頻焊機(jī)(采用50赫茲交流電源)、脈沖焊機(jī)(直流脈沖焊機(jī)、儲(chǔ)能焊機(jī)等)、變頻焊機(jī)(如低頻焊機(jī))。

什么時(shí)候神器和電極一定時(shí)，神器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(dǎo)電性差(如不銹鋼)電阻率低的金屬其導(dǎo)電性好(如鋁合金)。因此，點(diǎn)焊不銹鋼時(shí)產(chǎn)熱易而散熱難，點(diǎn)焊鋁合金時(shí)產(chǎn)熱難而散熱易.點(diǎn)焊時(shí)，前者可用較小電流(幾千安培)，和后者就必須用很大電流(幾萬(wàn)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(guān)。

為了保證熔核的大小和焊點(diǎn)的強(qiáng)度，焊接時(shí)間和焊接電流可以在一定范圍內(nèi)互補(bǔ)。為了獲得一定的焊點(diǎn)強(qiáng)度，可以使用大電流和短時(shí)間（強(qiáng)條件，也稱為硬代碼），或者小電流和長(zhǎng)時(shí)間（弱條件，也稱為軟代碼）。用過(guò)的。硬規(guī)格或軟規(guī)格的選擇取決于所用焊接機(jī)的性能，厚度和功率。對(duì)于不同特性和厚度的金屬，電流和時(shí)間有上限和下限，使用時(shí)應(yīng)優(yōu)先使用。

電極壓力對(duì)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，和焊接電流增大的幅度卻不大，不能影響因R減小引起的產(chǎn)熱減少。因此，焊點(diǎn)強(qiáng)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(shí)，增大焊接電流。

分類

點(diǎn)焊按用途可以分成萬(wàn)能式（通用式、專用式）點(diǎn)焊；

按同時(shí)焊接的焊點(diǎn)數(shù)量為：有單點(diǎn)式、雙點(diǎn)式、多點(diǎn)式；

根據(jù)導(dǎo)電方式，分為單面和雙面；

根據(jù)增壓機(jī)構(gòu)的傳動(dòng)方式，分為：腳踏板，馬達(dá)凸輪型，氣動(dòng)型，液壓型，復(fù)合型（氣動(dòng)液壓型）；

根據(jù)操作特點(diǎn)：非自動(dòng)化和自動(dòng)化；

按安裝的方法分為：固定式，移動(dòng)式或輕便式（懸掛式）點(diǎn)焊；

根據(jù)焊接機(jī)可移動(dòng)電極（通常是上部電極）的移動(dòng)方向，可分為：垂直行程（電極線性移動(dòng)）和圓形行程。

工作準(zhǔn)則

編輯

點(diǎn)焊的工藝過(guò)程為開通冷卻水;將焊件表面清理干凈，裝配準(zhǔn)確后，送入上、下電極之間，施加壓力，使其接觸良好;通電使兩神器接觸表面受熱，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(diǎn);去除壓力，取出神器。焊接電流、電極壓力、通電時(shí)間及電極工作表面尺寸等點(diǎn)焊工藝參數(shù)對(duì)焊接質(zhì)量有重大影響。

點(diǎn)焊利用正負(fù)兩極在瞬間短路時(shí)產(chǎn)生的高溫電弧來(lái)熔化電極間的被焊材料，來(lái)達(dá)到使它們結(jié)合的目的。點(diǎn)焊的結(jié)構(gòu)十分簡(jiǎn)單，說(shuō)白了就是一個(gè)大功率的變壓器，將220V交流電變?yōu)榈碗妷?，大電流的電源，可以是直流的也可以是交流的。電焊變壓器有自身的特點(diǎn)，就是具有電壓急劇下降的特性。

電極點(diǎn)火后，電壓下降，調(diào)節(jié)焊接機(jī)的工作電壓，除了初級(jí)220/380電壓轉(zhuǎn)換外，次級(jí)線圈還具有抽頭來(lái)改變電壓，并且還有一個(gè)烙鐵鐵心調(diào)整可調(diào)鐵心。焊接機(jī)通常是使用電感原理制成的大功率變壓器。電感在打開和關(guān)閉時(shí)都會(huì)產(chǎn)生巨大的電壓變化。在瞬時(shí)短路期間，由正極和負(fù)極產(chǎn)生的高壓電弧用于熔化電極上的焊料。以達(dá)到將它們結(jié)合起來(lái)的目的。

點(diǎn)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(diǎn)的電阻焊方法。點(diǎn)焊多 　用于薄板的連接，如飛機(jī)蒙皮、航空發(fā)動(dòng)機(jī)的火煙筒、汽車駕駛室外殼等。點(diǎn)焊焊接變壓器是點(diǎn)焊電器，它的次級(jí)只有一圈回路。上、下電極與電極臂既用于傳導(dǎo)焊接電流，又用于傳遞動(dòng)力。冷卻水路通過(guò)變壓器、電極等部分，以免發(fā)熱焊接時(shí)，應(yīng)先通冷卻水，然后接通電源開關(guān)。電極的質(zhì)量直接影響焊接過(guò)程、焊接質(zhì)量和生產(chǎn)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(shí)，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(diǎn)焊和凸焊的焊接循環(huán)由四個(gè)基本階段(點(diǎn)焊過(guò)程)：

(1)預(yù)壓階段——電極下降到電流接通階段，確保電極壓緊神器，使神器間有適什么時(shí)候壓力。

(2)焊接時(shí)間——焊接電流通過(guò)神器，產(chǎn)熱形成熔核。

（3）維護(hù)時(shí)間-切斷焊接電流，繼續(xù)保持焊條壓力，直到熔核凝固到足夠的強(qiáng)度為止。

（4）休息時(shí)間-焊條開始上升，焊條再次開始下降，下一個(gè)焊接周期開始。

為了提高焊接接頭的性能，有時(shí)有必要在基本循環(huán)中添加以下一項(xiàng)或多項(xiàng)內(nèi)容：

(1)加大預(yù)壓力以消除厚神器之間的間隙，使之緊密貼合。

(2)用預(yù)熱脈沖提高金屬的塑性，使神器易于緊密貼合、防止飛濺;凸焊時(shí)這樣做可以使多個(gè)凸點(diǎn)在通電焊接前與平板均勻接觸，以保證各點(diǎn)加熱的一致。

機(jī)械用途

編輯

點(diǎn)焊使用方法：

1.在焊接過(guò)程中，應(yīng)調(diào)整電極棒的位置，以便在將電極按在焊件上時(shí)，電極臂保持彼此平行。

2.可以根據(jù)焊件的厚度和材料選擇電流調(diào)節(jié)開關(guān)級(jí)。開機(jī)后，電源指示燈應(yīng)亮起。可以通過(guò)調(diào)節(jié)彈簧壓力螺母并改變其壓縮程度來(lái)調(diào)節(jié)電極壓力。

3、在完成上述調(diào)整后，可先接通冷卻水后再接通電源準(zhǔn)備焊接。焊接過(guò)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(shí)，電源觸頭開關(guān)接通，于是變壓器開始工作次級(jí)回路通電使焊件加熱。什么時(shí)候焊接一定時(shí)間后松開腳踏板時(shí)電極上升，借彈簧的拉力先切斷電源而后恢復(fù)原狀，單點(diǎn)焊接過(guò)程即告結(jié)束。

4.焊件的準(zhǔn)備和組裝：焊接前必須清除鋼焊件上的所有污垢，油污，水垢和鐵銹。對(duì)于熱軋鋼，最好首先通過(guò)酸洗，噴砂或使用砂輪去除氧化皮來(lái)選擇焊接區(qū)域。盡管可以清洗未清洗的焊件，但會(huì)嚴(yán)重降低電極的使用壽命，并且還會(huì)降低生產(chǎn)效率和點(diǎn)焊質(zhì)量。對(duì)于薄涂層的中低碳鋼，可以直接焊接。

此外，使用時(shí)，用戶可以參考以下過(guò)程數(shù)據(jù)：

1、焊接時(shí)間：在焊接中低碳鋼時(shí)，本焊機(jī)可利用強(qiáng)規(guī)范焊接法(瞬時(shí)通電)或弱規(guī)范焊接法(長(zhǎng)時(shí)通電)。在大量生產(chǎn)時(shí)應(yīng)采用強(qiáng)規(guī)范焊接法，它能提高生產(chǎn)效率，減少電能消耗及減輕神器變形。

2.焊接電流：焊接電流取決于焊件的尺寸，厚度和接觸面。通常，金屬電導(dǎo)率越高，電極壓力越大，焊接時(shí)間越短。此時(shí)所需的電流密度也增加。

3.電極壓力：電極向焊接件施加壓力的目的是減少焊接點(diǎn)的接觸電阻并確保形成焊接點(diǎn)時(shí)所需的壓力。

安全

編輯

1.在現(xiàn)場(chǎng)使用時(shí)，應(yīng)有防雨，防潮，防曬棚，并應(yīng)安裝相應(yīng)的消防設(shè)備。

2.在焊接地點(diǎn)的10m范圍內(nèi)，不得堆疊易燃易爆材料，例如油，木材，氧氣瓶和乙炔發(fā)生器。

3.焊接作業(yè)和合作人員必須穿戴要求的勞動(dòng)保護(hù)設(shè)備。必須采取安全措施以防止諸如電擊，高空墜落和氣體中毒之類的事故。

4.連接到次級(jí)抽頭的銅板應(yīng)緊固，端子應(yīng)有墊圈。在關(guān)閉之前，應(yīng)仔細(xì)檢查接線螺母，螺栓和其他零件，并確保它們完整無(wú)缺，沒(méi)有松動(dòng)或損壞。端子處有保護(hù)蓋。

5.使用前，應(yīng)檢查并確認(rèn)初、次級(jí)線接線正確，輸入電壓符合電焊機(jī)的銘牌規(guī)定，知道點(diǎn)焊焊接電流的種類和適用范圍。接通電源后，嚴(yán)禁接觸初級(jí)線路的帶電部分。初、次級(jí)接線處必須裝有防護(hù)罩。

6.移動(dòng)點(diǎn)焊時(shí)，應(yīng)切斷電源，不得用拖拉電纜的方法移動(dòng)焊機(jī)。什么時(shí)候焊接中突然停電時(shí)，應(yīng)立即切斷電源。

7.焊接銅，鋁，鋅，錫，鉛等有色金屬時(shí)，必須在通風(fēng)良好的地方進(jìn)行，焊接人員應(yīng)佩戴防毒面具或呼吸過(guò)濾器。

8.多臺(tái)點(diǎn)焊集中使用時(shí)，應(yīng)分接在三相電源網(wǎng)絡(luò)上，使三相負(fù)載平衡。多臺(tái)焊機(jī)的接地裝置，應(yīng)分別由接地極處引接，不得串聯(lián)。

9.嚴(yán)禁在運(yùn)行中的壓力管道，裝有易燃易爆材料和受壓部件的容器上焊接。

10.焊接預(yù)熱零件時(shí)，應(yīng)設(shè)置擋板以將輻射熱與預(yù)熱焊接零件隔離開。

安裝及保養(yǎng)

編輯

為了確保人身安全，使用前必須將焊接機(jī)正確接地。在使用焊接機(jī)之前，請(qǐng)先使用500V兆歐表測(cè)試焊接機(jī)的高壓側(cè)與機(jī)殼之間的絕緣電阻不小于2.5兆歐，然后才能通電。在打開包裝和檢查之前，必須在檢查過(guò)程中切斷電源。焊機(jī)首先要通水，然后再進(jìn)行焊接，嚴(yán)禁無(wú)水工作。冷卻水應(yīng)確保在5--30°C的入口壓力為0.15-0.2MPa的情況下供應(yīng)工業(yè)用水。冬季焊接機(jī)完工后，使用壓縮空氣吹送管道中的水，以避免水管凍結(jié)和破裂。

焊接機(jī)的導(dǎo)線不應(yīng)太細(xì)或太長(zhǎng)，焊接時(shí)的電壓降不得大于初始電壓的5％，初始電壓不得偏離電源電壓的±10％。在操作焊接機(jī)時(shí)，應(yīng)戴上手套，圍裙和防護(hù)眼鏡，以免火花飛濺出火花?；瑒?dòng)部件應(yīng)保持良好潤(rùn)滑，使用后應(yīng)清除金屬飛濺物。新焊機(jī)使用24小時(shí)后，應(yīng)擰緊各部分的螺釘一次，尤其要注意銅質(zhì)撓性接頭與電極之間的連接螺釘。使用后，應(yīng)經(jīng)常清除電極棒和電極臂之間的氧化，以確保良好的接觸。

使用焊接機(jī)時(shí)，如果發(fā)現(xiàn)交流接觸器不合適，則意味著電網(wǎng)電壓過(guò)低。用戶應(yīng)首先解決電源問(wèn)題，僅在電源正常后才能使用。應(yīng)該指出的是，如果在新購(gòu)買的焊接機(jī)的半個(gè)月內(nèi)出現(xiàn)主要部件的質(zhì)量問(wèn)題，則可以更換新的焊接機(jī)或主要部件。焊接機(jī)的主要部件保修一年，并提供長(zhǎng)期維護(hù)服務(wù)。正常情況下，用戶通知工廠后，根據(jù)距離可以在三到七天內(nèi)到位。由于用戶原因?qū)附訖C(jī)造成的損壞不在保修范圍之內(nèi)。易損件和易損件不在保修范圍內(nèi)。

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(dǎo)熱性關(guān)系著熱量的產(chǎn)生和散失，因此，電極的形狀和材料對(duì)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(diǎn)強(qiáng)度將降低。神器表面的氧化物、污垢、油和其他雜質(zhì)增大了接觸電阻。過(guò)厚的氧化物層甚至?xí)闺娏鞑荒芡ㄟ^(guò)。局部的導(dǎo)通，由于電流密度過(guò)大，則會(huì)產(chǎn)生飛濺和表面燒損。氧化物層的存在還會(huì)影響各個(gè)焊點(diǎn)加熱的不均勻性，引起焊接質(zhì)量波動(dòng)。因此徹底清理神器表面是保證獲得優(yōu)質(zhì)接頭的必要條件。

故障排除

1.踩下踏板，焊機(jī)不工作，電源指示燈不亮：

一個(gè)。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(guān)的觸點(diǎn)，交流接觸器的觸點(diǎn)和分動(dòng)開關(guān)的觸點(diǎn)是否接觸良好或燒毀。

2、電源指示燈亮，神器壓緊不焊接：

一個(gè)。檢查腳踏板行程是否到位以及腳踏開關(guān)是否接觸良好。

b.檢查壓力桿彈簧螺絲是否調(diào)整適什么時(shí)候。

3.焊接過(guò)程中意外飛濺：

一個(gè)。檢查電極頭是否被嚴(yán)重氧化。

b.檢查焊接神器是否嚴(yán)重銹蝕接觸不良。

C。檢查調(diào)節(jié)開關(guān)是否太高。

d。檢查電極壓力是否過(guò)低以及焊接程序是否正確。

4.焊點(diǎn)有嚴(yán)重的凹痕并擠出：

一個(gè)。檢查電流是否太大。

b.檢查焊接神器是否有凹凸不平。

C。檢查電極壓力是否太大以及電極頭的形狀和橫截面是否合適。

5、焊接神器強(qiáng)度不足：

一個(gè)。檢查電極壓力是否過(guò)低，并檢查電極桿是否緊固。

b.檢查焊接能量是否太小，焊接神器是否銹蝕嚴(yán)重，使焊點(diǎn)接觸不良。

C。檢查電極頭與電極棒，電極棒與電極臂之間是否有過(guò)多的氧化物。

d。檢查電極頭的橫截面是否由于磨損而增大并且焊接能量是否降低。

e。檢查電極和銅的軟耦合及結(jié)合面是否被嚴(yán)重氧化。

6.焊接過(guò)程中交流接觸器的異常聲音：

一個(gè)。檢查焊接期間交流接觸器的輸入電壓是否比自釋放電壓低300V。

b。檢查電源線是否太細(xì)或太長(zhǎng)，導(dǎo)致線路電壓降太大。

C。檢查網(wǎng)絡(luò)電壓是否太低而無(wú)法正常工作。

d。檢查主變壓器是否短路，導(dǎo)致電流過(guò)大。

7.電焊機(jī)過(guò)熱現(xiàn)象：

一個(gè)。檢查電極支架與主體之間的絕緣電阻是否不良，是否引起局部短路。

b。檢查進(jìn)水壓力，水流量和供水溫度是否合適，并檢查水路系統(tǒng)是否被污垢阻塞，這會(huì)由于冷卻不良而導(dǎo)致電極臂，電極桿和電極頭過(guò)熱。

C。檢查銅質(zhì)撓性聯(lián)軸器以及電極臂，電極棒和電極頭的接觸面是否被嚴(yán)重氧化，從而導(dǎo)致接觸電阻增加并產(chǎn)生熱量。

d。檢查電極頭部分是否由于磨損而過(guò)度磨損，從而使焊機(jī)過(guò)載并產(chǎn)生熱量。

e。檢查焊接厚度和負(fù)載連續(xù)率是否超過(guò)標(biāo)準(zhǔn)，從而導(dǎo)致焊機(jī)過(guò)載和發(fā)熱[1]

利弊

電阻焊具有以下優(yōu)點(diǎn)：

1.形成熔核時(shí)，熔核總是被塑料環(huán)包圍，熔融金屬與空氣隔離，冶金過(guò)程很簡(jiǎn)單。

2.加熱時(shí)間短，熱量集中，熱影響區(qū)小，變形和應(yīng)力也小。通常無(wú)需在焊接后安排校正和熱處理過(guò)程。

3，不需要焊條，焊絲等填充金屬，氧氣，乙炔，氬氣等焊接材料，焊接成本低。

4.操作簡(jiǎn)單，易于實(shí)現(xiàn)機(jī)械化和自動(dòng)化，改善工作條件。

5.生產(chǎn)率高，無(wú)噪音，無(wú)有害氣體。在批量生產(chǎn)中，可以將其與其他制造工藝一起組裝在裝配線上，但是由于火花和飛濺而需要隔離閃光對(duì)焊。

電阻焊具有以下缺點(diǎn)：

1.缺乏可靠的非破壞性測(cè)試方法，只能通過(guò)對(duì)過(guò)程樣本和焊件進(jìn)行破壞性測(cè)試以及各種監(jiān)控技術(shù)來(lái)檢查焊接質(zhì)量。

2.點(diǎn)焊和縫焊的搭接接頭不僅增加了部件的重量，而且在兩塊板之間的熔核周圍形成了一個(gè)角度，從而降低了接頭的抗拉強(qiáng)度和疲勞強(qiáng)度。

3.設(shè)備功率大，機(jī)械化程度高，自動(dòng)化程度高，增加了設(shè)備成本。維護(hù)難度大，常用的大功率單相交流電焊機(jī)不利于電網(wǎng)的正常運(yùn)行，需要單獨(dú)配電。

電阻焊的主要方法有焊接，縫焊，凸焊和對(duì)接焊。

編輯

1、點(diǎn)焊的分類 點(diǎn)焊的種類很多，按電源類別可分為工頻、電容儲(chǔ)能、次級(jí)整流、直流沖擊波等四種；按電極類型可分為單頭、雙頭、三頭三種；按結(jié)構(gòu)形式可分為固定式、懸掛式、手提式三種；按壓力傳動(dòng)方式可分為杠桿式、氣壓式和液壓式三種。還有一些變型產(chǎn)品如鋼筋網(wǎng)片成形機(jī)、數(shù)控式程序控制點(diǎn)焊等。

2、點(diǎn)焊的型號(hào) 點(diǎn)焊型號(hào)還是采用JB1475-81規(guī)定的編制方法，類型代號(hào)為DN，主參數(shù)代號(hào)以公稱容量表示，鋼筋電焊中常用的wieDN系列短臂固定式和DN3系列長(zhǎng)臂固定式以及DN7系列多頭點(diǎn)焊。

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英文版：

Spot welding
The spot welding machine adopts the principle of double-sided double-point overcurrent welding. The two electrodes pressurize the artifact, so that the two layers of metal form some pressure contact resistance under the pressure of the two electrodes, and when the welding current flows from one electrode to the other When one electrode is formed, instantaneous thermal welding is formed at two contact resistance points. The welding current immediately flows from the other electrode to the electrode along the two artifacts, forming a loop, and will not damage the internal structure of the electrode. Welding artifact.

Chinese name

spot welding

use

Double-sided double-point overcurrent welding principle

form

Some contact resistance

press

Number of solder joints welded simultaneously



table of Contents

1 Introduction

2 Working Guidelines

3 Mechanical uses

4 Security

5 Installation and maintenance

6 Rebar spot welding



Introduction

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Spot welding can be divided into universal type (universal 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 and multi-point type; according to the conductive method, there are single-side and double-side According to the transmission mode of the pressing mechanism, there are foot type, motor-cam type, pneumatic type, hydraulic type, compound type (pneumatic hydraulic type); according to the characteristics of operation, there are non-automatic and automated; according to the installed Methods are divided into fixed, mobile or portable (hanging type); according to the moving direction of the movable electrode of the welding machine (usually the upper electrode), there are vertical stroke (the electrode moves linearly), circular stroke; according to the electrical energy The supply methods are divided into 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 artifact and electrode are fixed, the resistance of the artifact depends on its resistivity. Therefore, the resistivity is an important property of the material being welded. The metal with high resistivity has poor conductivity (such as stainless steel) and the metal with low resistivity has conductivity Good (such as aluminum alloy). Therefore, when spot welding stainless steel, it is easy to produce heat and difficult to dissipate heat. When spot welding aluminum alloy, it is difficult to produce heat and easy to dissipate heat. When spot welding, the former can use a smaller current (several thousands of amperes), and the latter must use a large current ( Tens of thousands of 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 size of the nugget and the strength of the solder joint, the welding time and welding current can be complementary within a certain range. In order to obtain a certain solder joint strength, a large current and a short time (strong condition, also called hard code), or a small current and a long time (weak condition, also called soft code) can be used. used. The choice of hard or soft specifications depends on the performance, thickness and power of the welding machine used. For metals with different characteristics and thicknesses, there are upper and lower limits for current and time, which should be used first.

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, and the increase in welding current is not large. 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 automatic spot welding machine

Spot welding can be divided into universal (universal, special) spot welding 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 method, it is divided into single-sided and double-sided;

According to the transmission mode of the booster mechanism, it is divided into: foot pedal, motor cam type, pneumatic type, hydraulic type, composite type (pneumatic hydraulic type);

According to operating characteristics: non-automated and automated;

According to the installation method, it is divided into: fixed, mobile or portable (hanging) spot welding;

According to the moving direction of the movable electrode (usually the upper electrode) of the welding machine, it can be divided into: vertical stroke (linear electrode movement) and circular stroke.



Working guidelines

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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; the energization makes the contact surfaces of the two artifacts heated and partially melted 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 artifact. Spot welding process parameters such as welding current, electrode pressure, energizing time, and electrode working surface size have a significant impact on welding quality.

Spot welding uses the high temperature arc generated by the positive and negative poles during an instantaneous short circuit to melt the welded material between the electrodes to achieve the purpose of combining them. The structure of spot welding is very simple. To put it bluntly, it is a high-power transformer, which converts 220V AC to 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 ignites, the voltage drops to adjust the working voltage of the welding machine. In addition to the primary 220/380 voltage conversion, the secondary coil also has taps to change the voltage, and there is also a soldering iron core to adjust the adjustable core. Welding machines are usually high-power transformers made using the principle of inductance. The inductance produces a huge voltage change when it is turned on and off. During the transient short circuit, the high voltage arc generated by the positive and negative electrodes is used to melt the solder on the electrodes. In order 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 spot welding transformer 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 surface of the upper and lower electrodes 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 artifact, so that there is appropriate pressure between the artifact.

(2) Welding time—The welding current passes through the artifact and generates heat to form a nugget.

(3) Maintenance time-cut off the welding current and continue to maintain the electrode pressure until the nugget solidifies to a sufficient strength.

(4) Rest time-The electrode begins to rise, the electrode begins 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 pre-pressure to eliminate the gap between the thick artifacts and make them fit closely.

(2) Use preheat pulse to improve the plasticity of the metal, make the artifact easy to fit closely and prevent splashing; 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

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How to use spot welding:

1. During the welding process, the position of the electrode rod should be adjusted so that the electrode arms remain parallel to each other when the electrode is pressed against the weldment.

2. The current adjustment switch stage can be selected according to the thickness and material of the weldment. After booting, the power indicator should light up. 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 continued to be pressed, the power contact switch is turned on, and the transformer starts to work. The circuit is energized to heat the weldment. When the electrode is lifted when the foot pedal is released after a certain time of welding, the power of the spring is first cut off and then restored to the original state, and the single-point welding process is ended.

4. Preparation and assembly of weldments: All dirt, oil, scale and rust on the steel weldments must be removed before welding. For hot rolled steel, it is best to first select the welding area by pickling, sandblasting or using a grinding wheel to remove scale. Although it is possible to clean uncleaned weldments, it will seriously reduce the service life of the electrode, and will also reduce production efficiency and spot welding quality. For thin-coated medium and low carbon steel, it can be directly welded.

In addition, when using, users can refer to the following process data:

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). In mass production, a strong standard welding method should be used, which can improve production efficiency, reduce power consumption and reduce artifact 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 applying pressure to the weldment is to reduce the contact resistance of the welding point and ensure the pressure required to form the welding point.



Safety

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1. When used in the field, there should be rain, moisture, sunscreen, and the corresponding fire equipment should be installed.

2. Within 10m of the welding site, flammable and explosive materials such as oil, wood, oxygen cylinders and acetylene generators shall not be stacked.

3. Welding operations and cooperative personnel must wear the required labor protection equipment. 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 fastened, and the terminal should have a washer. Before closing, carefully check the wiring nuts, bolts and other parts, and ensure that they are intact, not loose or damaged. There is a protective cover at the terminal.

5. Before use, you should check and confirm that the primary and secondary wires are connected correctly, the input voltage meets the nameplate requirements of the welding machine, and know the type and scope of spot welding welding current. 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 spot welding, the power supply should be cut off, and the welding machine must 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 welds 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 pipeline in operation, the container equipped with flammable and explosive materials and pressure parts.

10. When welding preheated parts, baffles should be set up to isolate radiant heat from preheated welded parts.



Installation and maintenance

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In order to ensure personal safety, the welding machine must be properly grounded before use. Before using the welding machine, please 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, and then it can be powered on. Before unpacking and inspecting, the power must be cut off during the inspection. The welding machine must be watered first, and then welded. It is strictly forbidden to work without water. The cooling water should ensure that industrial water is supplied at an inlet pressure of 0.15-0.2 MPa at 5--30 ° C. After the welding machine is completed in winter, use compressed air to blow the water in the pipe to avoid the water pipe freezing and breaking.

The wire of the welding machine 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. When operating the welding machine, gloves, apron and protective glasses should be worn to prevent sparks from splashing out. Sliding parts should be kept well lubricated, and metal splashes should be removed after use. After using the new welding machine for 24 hours, the screws of each part should be tightened once, especially paying attention to the connecting screw between the copper flexible joint and the electrode. After use, the oxidation between the electrode rod and the electrode arm should be removed frequently to ensure good contact.

When using a welding machine, if the AC contactor is found to be inappropriate, it means that the grid voltage is too low. The user should first solve the power supply problem and use it only after the power supply is normal. It should be pointed out that if the quality problems of the main parts occur within half a month of the newly purchased welding machine, the new welding machine or the main parts can be replaced. The main parts of the welding machine are guaranteed for one year and provide long-term maintenance services. Under normal circumstances, after the user informs the factory, it can be 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 wearing parts 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. Oxide, dirt, oil and other impurities on the artifact surface 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 artifact is a necessary condition to ensure high-quality joints.

Troubleshooting

1. Depress the pedal, the welding machine does not work, the power indicator does not light:

One. 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 contact of the transfer switch are in good contact or burned.

2. The power indicator light is on, and the artifact is not compressed and welded:

One. Check that the foot pedal travel is in place and the foot switch is in good contact.

b. Check when the pressure rod spring screw is adjusted.

3. Accidental spatter during welding:

One. Check whether the electrode tip is severely oxidized.

b. Check whether the welding artifact is badly corroded and has poor contact.

C. Check if the adjustment switch is too high.

d. Check whether the electrode pressure is too low and the welding procedure is correct.

4. The solder joint has serious dents and is extruded:

One. Check if the current is too large.

b. Check whether the welding artifact is uneven.

C. Check whether the electrode pressure is too high and the shape and cross section of the electrode tip are appropriate.

5. Insufficient welding artifact strength:

One. 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 artifact is seriously corroded, so that the welding point is poorly contacted.

C. Check whether there is excessive oxide between the electrode tip and the electrode rod, and between the electrode rod and the electrode arm.

d. Check whether the cross section of the electrode tip increases due to wear and whether the welding energy decreases.

e. Check whether the soft coupling of the electrode and copper and the bonding surface are severely oxidized.

6. Abnormal sound of AC contactor during welding:

One. Check whether the input voltage of the AC contactor is 300V lower than the self-release voltage during welding.

b. Check whether the power cord is too thin or too long, causing the line voltage to drop too much.

C. Check if the network voltage is too low to work properly.

d. Check whether the main transformer is short-circuited, resulting in excessive current.

7. Overheating phenomenon of electric welding machine:

One. Check whether the insulation resistance between the electrode holder and the main body is poor, and whether it causes a local short circuit.

b. Check whether the inlet water pressure, water flow and water supply temperature are appropriate, and check whether the waterway system is blocked by dirt, which may be caused by poor cooling