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Welding ball valve welding technology processing
Welding types are mainly divided into: 1, electrode arc welding; 2, submerged arc welding (automatic welding); 3, carbon dioxide gas shielded welding (automatic or semi-automatic welding); 4, MIG / MAG welding , TIG welding (TIG welding); 6, plasma arc welding six welding methods, each of the principles and applications are not the same, because it is not the focus of this article, so we can simply know, the following key to talk about Welding ball valve welding technology processing: Welding ball valve welding is actually different from the ordinary welding technology, because the valve chamber with non-metallic rubber and PTFE sealing material, can not be welded after the heat treatment. Layer welding process is a metal material repeatedly heating and cooling process, usually its welded joints are designed to narrow gap thick-walled submerged arc welding, and the use of all-welded valve body is the kind of large thickness Tubular welded joints.Therefore, the root of the welded joints of the valve body stress concentration, residual stress, poor quality organizations become the weak link in the valve structure, the current Of the two treatment methods are: 1. Is the heat treatment technology processing; 2. Is the joint processing; These two treatment methods will produce several times the stress concentration of normal stress, also make the engineers difficult to deal with.Thus, How to solve the welding ball valve body welded joints at the root of the gap stress concentration, residual stress, poor organization become the biggest problem of valve welding, Quancheng brand all-welded ball valve manufacturers here to everyone valve welding technology summary below, hoping to be able Help to understand the ball valve welding technology friends! Now the body of the welding process are as follows. 1, the body of the technical requirements (1) seam welded body without deformation, including the shaft flange (45 steel ) (2) The heating area of ​​the valve body can not be too wide and the temperature can not be too high, otherwise the sealing device in the valve body will be destroyed. (3) No welding can occur. (4) The pressure is guaranteed to be over 10MPa. Structure According to the above technical requirements, to determine the weld is not welded through the weld.Therefore, the requirements of the butt weld form both to ensure assembly and can not be penetrated.After the test And finally determine the weld form 3, the valve body material Because the valve body is ZG15 Ⅱ, so the chemical composition of the valve body before the test, the test results and casting the same test results, in line with the design requirements. 4, assembly The use of hydraulic press modified flip tire positioning, and in the surrounding two halves of the bolt fastening, adjust the tightness test, ball and body to meet the design requirements between the outside .5, welding process taking into account the technical requirements of the valve, the final choice of the MAG Of CO2 welder ER50-6 (Ø1.0) wire is chosen for the welding material. The selected ER50-6 (Ø1.0) wire meets the requirements of ZG15Ⅱ according to the principle of equal strength of welding materials. The shielding gas adopts 82% Ar + 18% CO2 mixed gas 5.1 Positioning welding Due to the severe hardenability of cast steel and 45 steel, it should be preheated before positioning welding. Oxygen-acetylene flame should be used on both sides of the weld, Within the range of uniform heating to 75 ~ 100 ℃ (45 steel bias), without affecting the sealing device shall prevail, with far-infrared thermometer measurements. Before welding the surface of the weld seam on both sides of the surface of the oxide scale and rust angle polisher polished metal luster. Locate 6 points 50 mm away from the edges on both sides of the weld and measure the distance between the two points with a caliper in order to measure the amount of shrinkage. 5.2 back cover welding Considering ZG15 Ⅱ material rigidity, poor plastic characteristics, so the choice of welding specifications should take a small welding parameters, that is, a small welding heat input. In the premise of ensuring the quality of the weld, try to improve the welding speed and reduce the fusion ratio, in the deformation to take a multi-layer multi-channel 6 section symmetry welding method; attention to each welding layer with calipers to measure the positioning point, the amount of shrinkage Control until welding finished. In addition to the first and last one, between the other hammering method used to eliminate stress treatment. 6, the last step after the completion of welding, through the pressure test (gas tight) weld no leakage, the sealing surface to meet the technical requirements, after X-ray inspection, the weld itself no porosity, slag, fusion, cracks and other welding defects, valve Core rotation to meet the technical requirements.