平面鋼閘門結構生產制造工作，質量的控制貫穿整個工作的全過程，作者認為門葉焊接是閘門焊接的關鍵，門葉的焊接變形控制必須得到有效控制。如果焊前不充分交底和焊接把關，焊后會產生較大的焊接變形，甚至使變形無法修復而造成構件報廢，所以，我們專門制訂了焊接工藝設計。對閘門的一、二類焊縫編制了“主控項目”焊接工藝卡，要求參加閘門焊接的合格焊工嚴格遵循工藝紀律及各項技術要求，有效地控制了閘門的焊接變形，提高了產品的生產質量，收到了良好的經濟效益。
　　 　　2. 閘門的技術要求
　　2.1 鋼閘門的焊接，除按標書技術要求及水利水電工程鋼閘門制造安裝及驗收規范來確保焊接質量符合規定外，焊接變形則是控制整體制造的首要問題
　　2.2 門葉整體拼裝組對時，各部位間隙要嚴格控制。如:主梁與面板，主梁腹板、翼板與隔板，主梁與邊梁之間等結合部位要頂緊裝配，各組合面的局部間隙均不大于1mm，嚴禁強行組裝。
　　2.3 整體閘門制作若分節，按制造結構的設計工藝要求，整體拼裝后為保證整體閘門門葉的焊接要求，在各節連接部位之間，每隔500mm左右要有臨時加強肋板，以加強閘門門體的剛度。
　　2.4 門葉組裝完畢后，由檢查人員對整體尺寸、組裝質量、坡口大小、組合間隙等進行嚴格認真的檢查。如不合格必須按要求進行整改，直至合格為止。
　　2.5 閘門檢查合格后，由合格焊工對閘門進行整體加固。每300mm左右加固長度必須要有一段長100mm左右的加固焊(焊腳高度不宜超過設計焊腳或坡口的1/2~1/3)。加固焊要求同正式焊要求一致，不得有裂紋、夾渣、氣孔等焊接缺陷。
　　2.6 焊材使用時，應按焊接工藝設計要求進行烘焙后使用。焊工應隨身攜帶焊條保溫筒，做到隨用隨取。焊條在保溫筒內的存放時間不得超過4h，否則焊材應重新烘焙，重復烘焙次數不得超過2次。焊劑烘干需按單位制度要求或使用說明書進行。焊接參數見表1。
　　2.7 當局部組裝間隙超過5mm時，且長度不大于焊縫全長的15%，允許堆焊處理。堆焊時嚴禁填充異物且堆焊后進行修復直至達到設計要求。
　　2.8 嚴格按照焊接規范執行，具體焊接參數見表1。多層多道焊時，應注意焊道周圍的清理工作，層間接頭應錯開50mm以上，嚴禁在非焊接部位的母材上隨意引弧。
　　2.9 焊接熱輸入、焊接速度和焊接層數。焊接熱輸入太大時，會導致熱影響區性能下降、尤其是韌性降低，為了盡可能減小這種影響的程度，獲得良好性能的焊縫和成型，就必須對焊接熱輸入加以控制。焊接速度應在焊接熱輸入允許范圍內。焊接層數根據板厚、焊腳尺寸、焊條直徑來確定，每層厚度應小于6mm。
　　2.10 在埋弧焊時，對于一、二類焊縫必須參照“焊接工藝卡”進行施焊。
　　2.11 埋弧焊拼板、T型梁船位焊接，焊縫的引弧、熄弧處應加引弧或熄弧板，一般應在端部50mm 
　　處施加。
　　2.12 儀表、機械、焊機等應工作正常。焊絲不得有小角度彎曲，焊絲和工件表面不得有油、水、銹等污物。
　　2.13 一、二類焊縫中如有缺陷需修補時，應由持有效期內的合格焊工按有關工藝進行。對于一、二類焊縫，同一位置的返修次數不宜超過2次。超過2次的返修處理，需經總工程師批準，且做出返修工 
　　藝和返修記錄。
　　 
　　3. 焊接變形產生的原因
　　焊接變形產生的最根本原因是焊件受熱或冷卻不均勻，焊縫金屬的收縮、金相組織的變化及焊件的剛性是產生或影響焊接應力和變形的重要原因。由以上分析可見，焊接應力變形產生的根源是焊接受熱不均，膨脹不自由，因而產生不均勻壓縮塑性變形所造成的。這種壓縮塑性變形在隨后的冷卻收縮過程中，如果工件板面較窄，厚度較薄，收縮阻礙較小，就表現為焊縫寬度、長度方向的收縮變形。否則，如果板面較寬，厚度較大，焊縫縱向的冷卻收縮受到兩側冷金屬的阻礙，就會對冷收縮金屬產生拉伸作用，并在工件中殘留較大的殘余應力。如果焊接結構的剛度較大，焊縫的橫向收縮受到較大的限制，則在這些結構中還將殘留巨大拘束應力。采 
　　用合理的工藝手段，使焊接收縮能自由的釋放，或互相抵消，或在焊接過程中消除，這樣可使焊接應力變形都較小。
　　 
　　4. 焊接變形的控制要點
　　4.1 在組裝和連接一個結構或組合構件的部件時，以及在焊接加強部件至構件時，焊接順序應使焊接變形和收縮最小。
　　4.2 在焊接過程中，所有焊接的順序應盡可能使焊接進展時所施加熱量均衡(注:焊接線能量確定時)。
　　4.3 在構件施焊時，焊接走向應從工件相對固定的點開始，向有較大自由位移的點移動。
　　4.4 在組裝好的構件中，應先焊收縮量較大接頭(即厚板坡口等)，后焊收縮量較小的接頭，在焊接時，要盡可能沒有約束力或約束力較小為好。
　　4.5 對于閘門的工字型焊接主梁、T型梁或組合件的每個部件(即小組、中組的結構件)，應在小組、中組焊接前，事先應全部拼接、校正好后再組對。
　　 
　　5. 閘門的焊接工藝
　　閘門組裝完工后進行整體焊接。為了保證門葉尺寸、焊接質量和控制焊接變形，要求由4名焊工完成作業任務，對于小型閘門，由2名焊工完成作業。按作業順序和方向進行施工，由4名焊工采用相同的焊接規范，同時由中心向兩側分段、間隔、對稱進行焊接。構件空間位置焊接順序:先焊立焊，后焊貼腳焊，最后其余焊縫。
　　 
　　6. 焊接檢驗
　　6.1 外觀檢驗執行DL/T5018-94《水利水電工程鋼閘門制造及驗收規范》標準規定。
　　6.2 無損檢測執行GB3323-87《鋼熔化焊對接接頭射線照相和質量分級》、GB11345-89《鋼焊縫手工超聲波探傷方法和探傷結果分析》標準規定。無損檢驗均應在焊后24h進行In the production and manufacture of planar steel gate structure, the quality control runs through the whole process of the work. The author considers that the welding of gate blade is the key to the welding of gate, and the welding deformation control of gate blade must be effectively controlled. If there is insufficient cross-over before welding and welding checkpoint, there will be large welding deformation after welding, even the deformation can not be repaired and the components will be scrapped. Therefore, we specially formulated the welding process design. For the first and second type welds of the gate, the welding process card of "main control project" has been compiled, requiring qualified welders to take part in the welding of the gate to strictly follow the process discipline and various technical requirements, effectively controlling the welding deformation of the gate, improving the production quality of the product and receiving good economic benefits. 2. Technical requirement of gate. Welding of 2.1 steel gate, besides ensuring the welding quality in accordance with the technical requirement of tender and the specifications of manufacture, installation and acceptance of steel gate in water conservancy and Hydropower projects, is the primary problem to control the overall manufacturing. When 2.2 door blades are assembled together, the clearance of each part should be strictly controlled. For example, the main girder and the panel, the web of the main girder, the flange and the partition of the main girder, and the joint between the main girder and the side girder should be tightly assembled, and the local clearance of each combination surface should not be greater than 1 mm. Forced assembly is strictly prohibited. 2.3 If the integral gate is divided into sections, according to the design process requirements of the manufacturing structure, in order to ensure the welding requirements of the integral gate blades after the integral assembly, temporary ribs should be strengthened every 500 mm or so between the connecting parts of each section to strengthen the stiffness of the gate body. After 2.4 door blades are assembled, the inspectors will examine the overall size, assembly quality, groove size and assembly clearance strictly and seriously. If they are not qualified, they must be rectified as required until they are qualified. After the 2.5 gate is qualified, the qualified welder shall reinforce the gate as a whole. Every 300 mm or so reinforcement length must have a reinforcing welding with a length of about 100 mm (the height of the welded foot should not exceed 1/2 to 1/3 of the designed welded foot or groove). The requirement of reinforcement welding is consistent with the requirement of formal welding, and no welding defects such as cracks, slag inclusion and pore are allowed.  When using 2.6 welding material, it should be baked and used according to the requirements of welding process design. Welders should carry the welding rod insulating cylinder with them, so that they can be used as they like. The storage time of the welding rod in the incubator shall not exceed 4 hours, otherwise the welding material shall be re-baked and the number of repeated baking shall not exceed 2 times. Flux drying should be carried out according to unit system requirements or instructions. Welding parameters are shown in Table 1. 2.7 Surfacing treatment is allowed when the assembly clearance exceeds 5 mm and the length is not more than 15% of the total length of the weld. It is strictly forbidden to fill foreign body during surfacing and repair it after surfacing until it meets the design requirements. 2.8 is strictly in accordance with the welding specifications. The specific welding parameters are shown in Table 1. In multi-layer and multi-pass welding, attention should be paid to the cleaning work around the weld bead. The indirect joint of the layer should be staggered more than 50 mm. Arc initiation on the base metal of the non-welded part is strictly prohibited. 2.9 Welding heat input, welding speed and number of welding layers. When the welding heat input is too large, the performance of HAZ will decrease, especially the toughness. In order to minimize the influence and obtain good welding seam and forming performance, it is necessary to control the welding heat input. Welding speed should be within the allowable range of welding heat input. The number of welding layers is determined by plate thickness, foot size and electrode diameter. The thickness of each layer should be less than 6 mm. 2.10 In submerged arc welding, the first and second class seams must be welded with reference to the "welding process card". 2.11 submerged arc welding tailor plate and T-beam seam welding. Arc ignition or arc extinguishing plate should be applied at the starting and extinguishing points of weld seam, generally at the end of 50mm. 2.12 Instruments, machinery and welding machines should work normally. Welding wires shall not be bent at small angles, and no oil, water, rust and other contaminants shall be found on the surface of welding wires and workpieces. If any defects in Class I and II welds need to be repaired, the qualified welders within the validity period shall follow the relevant process. For type 1 and type 2 welds, the number of repairs at the same position should not exceed 2 times. Over two repairs should be approved by the Chief Engineer, and the repairs process and record should be made. 3. The most fundamental cause of welding deformation is the uneven heating or cooling of the weld. The shrinkage of the weld metal, the change of the metallographic structure and the rigidity of the weld are the important reasons for producing or influencing the welding stress and deformation. From the above analysis, it can be seen that the root cause of welding stress and deformation is the uneven heating and expansion of welding, resulting in uneven compressive plastic deformation. In the subsequent cooling shrinkage process, if the workpiece plate surface is narrower, the thickness is thinner and the shrinkage hindrance is smaller, the shrinkage deformation in the width and length direction of the weld seam is shown. Otherwise, if the plate surface is wider and the thickness is larger, the longitudinal cooling shrinkage of the weld will be hindered by the cold metal on both sides, which will have a tensile effect on the cold shrinkage metal and residual stress in the workpiece. If the stiffness of the welded structure is large and the transverse shrinkage of the weld seam is limited, the huge restraint stress will remain in these structures. Reasonable technological means are adopted to release the welding shrinkage energy freely, or offset each other, or eliminate it in the welding process, so that the welding stress and deformation are smaller. 4. Control Points of Welding Deformation。