The method of welding with non-consumable electrode submerged arc

 

The method can be used in the welding industry. During welding with non-consumable electrode submerged arc exercise coercive pressure on the weld pool by the magnetic field of the solenoid. The magnitude of the magnetic induction is 0,12 - 0,20 TL. Solenoid set behind the electrode on the front side of the seam. The method can improve the formation of a welded joint by eliminating unilateral cutting without re-penetration weld. 2 Il.

The invention relates to mechanical engineering and can be used in the welding industry.

There is a method of submerged arc welding in which to eliminate cutting to improve the quality of the formation of a seam, perform the second pass of the surface arc with reduced current and increased arc voltage [welding in engineering/Handbook so 1/Ed. by N. A. Olshansky - M.: Mashinostroenie, 1978, S. 221].

The disadvantages are the counterpart of the decline in productivity with increasing labor and energy costs, the inadmissibility of repeated heating of a range of materials with low heat input (for example, the possibility of podelki welding area).

The known method arc svarc the e pressure on the liquid metal in the rear part of the tub [ed. St. USSR 1240530, MKI 23 To 8/13, 1986].

The disadvantages are the counterpart significant consumption of scarce protective gas, the leakage of liquid metal on the surface of the welded edges, unacceptably large for many materials the cooling rate of the weld metal.

The known method arc metal [ed. St. USSR 585000, MKI 23 To 9/08, 1973] , in which a pulsed magnetic field effect on the tail of the welding bath.

The disadvantage of analogue is that the electromagnet to provide a reversal of the volume forces acting in the interval of crystallization, and therefore the method cannot provide the offset of the molten metal in the desired direction, i.e. to eliminate the one-sided undercut.

The closest in technical essence and the achieved result is a method of arc welding in different security environments [SU 218349, MKI 23 To 9/16, 29.08.68], in which behind the arc creates a forced pressure on the weld pool.

The disadvantage of analogue is that when any proposed method of pressure, provided in the analog offset of the molten metal occurs in both directions from the axis of the weld and in the presence of unilateral cutting (Fig.1) is the leakage of liquid metal on the surface is their flow of inert gas or slider creates unacceptably large for many materials the cooling rate of the weld metal.

When the submerged arc welding in one pass of the material of a thickness exceeding 5 mm due to the large currents in the molten metal have significant volumetric electromagnetic force towards the axis of the weld. As a result, the edges of the seam having undercuts. Reduction of scores is possible to achieve a significant reduction in welding speed, but in this case you lose the main advantage of the method. Bilateral symmetrical undercut occurs when placing electrical power supply close enough to the axis of the weld. In real structures the current lead, as a rule, placed on one side of the seam (for example, when welding the annular and circular seams, the seams are not straight), so that the current density from the electrical power supply and more. This leads to the violation of the symmetry of the cross-section of the seam and there is a one-sided undercut on the side opposite to the electrical power supply (Fig.1).

The task to be solved by the invention is to improve the formation of a welded joint by eliminating unilateral cutting with simultaneous reduction of the weld reinforcement.

This object is achieved in that in the method of welding submerged arc forced pressure on the weld pool create permanent mvuu part of the welding bath. The interaction of the current flowing in the rear part of the weld pool, with the external magnetic field creates an electromagnetic force, displacing the molten metal in the direction of the expected cut, thereby eliminating the latter.

The solenoid is rigidly connected with the electrode angle of the burner and has with him a common nozzle, protecting the weld pool and the cooling part of the weld metal. The cross-section of the nozzle has the shape of an ellipse.

The value of magnetic induction In the solenoid, it is recommended to create a 0.12 to 2.0 Tesla. The smaller the value of induction does not provide the correct cutting with a larger value of induction, the formation of the cut from the opposite side of the seam. The magnitude of the magnetic induction is expected to increase with increasing depth of the required penetration (i.e., with increase of welding current).

The scheme of the action of the electromagnetic forces on the tail of the welding bath is shown in Fig.2, where 1 is the arcing zone, 2 - electrode, 3 - conductors, 4 - direction magnetic fields 5 - the direction of the current in the molten metal i, 6 - direction electromagnetic force fi7 - side of the seam, where it is expected the formation of a unilateral cut.

A specific example of implementation of the method.

Welding is carried out on the samples of the Z axis of the joint.

The welding process start the process plate with the gradual penetration of the electrode to a value of 3 mm, providing a penetration of up to 6 mm

Welding mode: welding current I=900 A, arc voltage Ud=12 V, welding speed VSt=10 m/h

Using a solenoid placed behind the electrode, create a magnetic field. The magnitude of the magnetic induction B=0.12 T.

While cooked sample Podrez is missing.

When welding databases filler wire in the sample occurs unilaterally cutting depth of 1.5...2 mm

Thus, the proposed method allows to eliminate one-sided undercut without re-penetration weld.

Claims

The method of welding with non-consumable electrode submerged arc forced pressure on the weld pool, characterized in that the forced pressure exercised by the magnetic field of a solenoid with a magnetic induction of 0.12 - 0.20 T installed behind the electrode on the front side of the seam.

 

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