Welding technique in the lower position. This allows to obtain the spatial position of welds of the highest quality as facilitates the selection of nonmetallic inclusions, gases from the molten metal weld pool. At the same time as the most favorable conditions for the formation of the weld metal as the molten metal weld pool is kept from leaking part of the edges.
Butt weld seams without bevel edge or V-, X-and U-shaped sutures skosom.Stykovye without bevel edge, depending on the thickness of the weld on one or both sides. At the end of this electrode perform transverse oscillations (see Fig. 12) with an amplitude determined by the desired width of the seam. You should carefully follow the uniform melting of the two welded edges throughout their thickness, and especially the joint between the bottom (root pass).
Single-pass welding with a V-shaped bevel edge is usually performed with transverse vibrations of the electrode on the entire width of the cuts to its completion so that the arc went out with a bevel edge on the untreated metal surface. However, in this case it is very difficult to ensure uniform penetration of the root weld along its entire length, especially when the magnitude of blunting the edges and the gap between them.
When welding seam with a V-shaped bevel edges in several passes to ensure good penetration of the first layer in the root cutting much easier. This is usually used electrodes with a diameter of 3-4 mm and welding are no transverse oscillations. Subsequent layers are performed depending on the thickness of the metal electrode of a larger diameter to the transverse vibrations. To ensure good penetration between the layers of previous joints and edges should be thoroughly cleaned of slag and spatter.
Fill groove with a width of sutures can be for all a breaker or individual rollers. In multipass welds the last roll to improve the appearance is sometimes possible to perform the entire width of cut (decorative layer).
Welding joints with X-or U-shaped bevel edges perform essentially the same as with the V-shaped bevel. However, in order to reduce the residual strain and stress, if possible, welding leads, applying each layer of the roller, or alternately on each side. Stitches from the X-or U-shaped bevel edges compared with the V-shaped have advantages, since the first case, 1.6-1.7 times the amount of weld metal decreases (increases the productivity of welding). In addition, the reduced angular deformation, and the possible lack of fusion of the root weld is formed in neutral with respect to the bending moment section. The lack of a U-shaped bevel edge - increased complexity of its receipt.
Butt welds can be done in different ways. When welding on the weight of the most difficult to weld root penetration and the formation of a good reverse bead on the entire length of the joint. In this respect, is more favorable to the welding of copper and the remaining removable stainless steel lining. In the copper lining for forming a reverse roller makes forming a groove. However, to prevent leakage of molten metal from the weld pool should be tight compression pads welded to the edges. In addition, the remaining metal lining increases the flow and not always technical. When using copper pads have difficulty accurately set along the edges forming the groove.
If the back of the possible approach to the root of the weld and allowed the back of the strengthening of the weld seam is suitable root jelly, followed by a small cross-section stacking the main seam. In some cases, the formation of incomplete penetration at the root of post weld seam ground defect at the root of the gas is cut, air-arc gouging, or mechanical methods, followed by the implementation of seam.
Weld fillet welds in the bottom position can be performed by two methods. Welding electrode in the vertical boat provides the most favorable conditions for penetration of the root joint and the formation of his gain. In essence, this technique resembles welding of butt joints with a V-shaped bevel edge as a seam is formed between the welded surfaces. However, this method requires careful assembly of the connection weld with a minimum gap in the joint to prevent leakage of molten metal into it.
When welding electrode is difficult to provide an inclined penetration weld on the lower plane (due to leakage at it molten metal) and to prevent undercut on the vertical plane (due to draining of the molten metal). Therefore, in this way are usually welded joints with the leg up to 6-8 mm. When welding fillet welds inclined electrode is difficult to ensure deep penetration into the root of the weld, so the unilateral or bilateral joints without bevel edges may form lack of fusion, which, when loading the seam will be the beginning of development of cracks. To prevent this, the compounds responsible for the metal thickness of 4 mm or more one-sided bevel is required, and at a thickness of 12 mm or more - double-sided bevel edges.
When welding electrode inclined multi-pass weld seams first performed on a horizontal plane. The formation of the subsequent roll is a partial retention of the molten metal weld pool underlying a roller. When welding fillet welds are used transverse oscillations of the electrode. Especially important is the correct choice of the trajectory of the welding electrode is inclined to prevent the occurrence of the above defects.
See also:
Manual Arc Welding
Introduction to Arc Welding
Creating and maintaining an arc
Ways to improve performance
Technique of upper and horizontal joints
Technique of the lower seam
Pipe Welding Technique
The Method
Arc Welding in Protective Gases
Electrodes for Manual Arc Welding
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