What are the welding improvement methods in the manufacturing process of environmental protection centrifugal fan impeller?

(1) First, fix the blade and the backboard according to the drawing, adjust the angle between the blade and the backboard, then rotate the backboard to the platform, and rigidly fix the backboard with the fixing fixture. Considering that welders are used to welding from inner ring to outer ring, radial warping will occur. Therefore, before the inner ring is fixed, a steel plate with δ = 5mm is padded under the inner ring to form a preset deformation of 2 ~ 3. Before welding, fix the upper end of the blade with a steel plate with δ = 12 mm (cut into strips with a width of 20mm, and the length depends on the blade spacing).

(2) When welding, two or more welders are selected to weld at the same time, and the symmetrical sectional welding method is adopted (i.e., the impeller is equally divided in roundness, and the angular deformation directions of the two welders cancel each other during welding). When welding, the welding process parameters should be the same and the welding speed should be the same. In this way, because two welders are welding at the same time, the welding angular deformation directions are opposite, and the angular deformation is basically similar, and the angular deformation can be offset by the fixed lath at the upper end of the blade, thus solving the angular deformation problem of the blade; At the same time, subsection welding is adopted, and the selection of welding parameters is strictly controlled in the welding process to reduce the wave deformation of the back plate in the circumferential direction and reduce the residual stress after welding.

(3) After the blade is welded to the back plate, after cleaning and inspection, it should be evenly heated by flame in the radial direction according to the welding sequence, and the temperature should be within the annealing temperature range, so as to eliminate part of the residual stress after welding. After heating and cooling, grind off the fixed slats at the upper end of the blade, fix the front stock on the blade according to the drawing, and then remove the back plate for reinforcement.

(4) Fix the assembled impeller on the fixture and weld the fillet weld between the front plate and the blade. The welding sequence and method are the same as the fillet weld between the back plate and the blade, and the welding parameters should be strictly controlled. After welding is completed, according to the welding sequence after cleaning, inspection and defect elimination, the flame is evenly heated along the radial direction, and the temperature is within the annealing temperature range. After cooling, the fixed fixture is removed (see figure 1). If more than two welders cannot be arranged for welding in production, 1 welder can also be arranged for welding. Before welding, the support frame can be fixed on the left and right sides of 3 ~ 5 blades to control the angular deformation, but the welding sequence should be the same as that of two welders.