SU647075A1 - Arc-welding method - Google Patents

Description

one

The invention relates to the welding of metal plates of large-sized structures, welds in various spatial settings, in particular, to welding of non-rotary annular joints of pipelines with a diameter of several meters or meridional joints of spherical tanks welded in a non-rotatable position.

At present, arc welding with the forced formation of a seam with a copper cooled creeper is used for welding such structures, moving as far as filling is completed along with the welding machine.

However, this method allows. weld in a single pass thickness of no more than 10-12 mm, which limits its use.

Other known methods of single-pass welding with free seam formation, in which welding is carried out with reciprocating movements of the welding electrode from the root of the seam to the top, under constant HfciDM within 30-90 angles to the surface of the welded parts 2j or with complex electrical oscillations

2

yes ijf. These methods have a relatively low productivity, which is determined by the conditions for the formation of the weld pool in different spatial positions, limiting the strength of the welding current to values of 150-200A.

The closest in technical essence and the achieved result to the described invention is a method of arc welding with forced forming of a seam, in which a welding field is affected by a transverse magnetic field. In this method, the melt pool sheet is coupled with the condomotor forces generated by a constant transverse magnetic field and welding current flowing through the melt due to slip following the welding bath of the current lead of the welding circuit ensuring the constant current flow in the welding bath 4 .

To hold the bath during welding of steel with a thickness of more than 10-15 mm in one pass, taking into account its considerable mass, a high strength of the transverse, magnetic field is required, which deteriorates the stability of arc burning. The purpose of the invention is to increase the productivity of the welding process, performed in a single pass in the lower and ceiling voltages, by maintaining the welding process with two different arcs. . This is achieved by the fact that the proposed method of arc welding with the forced formation of a seam, which is affected by a transverse magnetic field on the weld pool, arcs are distributed in the longitudinal direction; axial junction plane at a distance from one another equal to the difference in thickness. the area of the welded product and the radii of the arcs, with. This uses an inhomogeneous magnetic field with a gradient of magnetic inductances increasing towards the root of the seam, and the magnitude of the gradient is chosen as the specific weight of the weld pool, and in order to ensure the stability of the process of testing the random perturbations G, the magnetic field of the weld pool is welded, the welded welding surface is welded, and the welder is welded. welding speed vector set; .Zhite noBoiKH-tejTtbHUM. By switching on two arcs on different polarities, the directional current flow through the liquid metal is ensured, and the inhomogeneous transverse magnetic field of it 3: 3 of this form is applied to it, and the corresponding gable creates a non-uniform field, compensating for the velocity of the body. svarchnoy. baths, which prevents leakage in the lower and inner ganging positions. The need to match the magnetic induction of the specific induction of the specific metal ID of a metal is determined by the shape of the hydrostatic pressure profile, which is balanced by: the ponderomotive force of the corresponding form. To compensate for the hydrostatic pressure of the bath, an effective smaller force is required than to hold the mass of the weld pool in single-pass welding of metal of the same thickness. This circumstance PBZ. It is possible to use in the described welding method a much smaller NPR. The yost of the transverse magnetic field and the significantly greater strength of the welding current, which increases the critical amount of the weld pool and the manufacturer of the Process. FIG. 1 shows a diagram of the method in the lower position; in Fig.2 a section aa of fig. one; in fig. 3 - in the TORAL. OCHE position in Fig. 4 - section B-B of FIG. 3 .. At phi-d.1-4, the following conventional notation is accepted: S - thickness welded Ogheetall; 5- magnetic induction vector; 5.- current vector ;; aaa3 is a magnetic induction gradient; ®.0- polarity of electrodes; St. welding direction. Two electrode wires 1 connected to different polarities are supplied. with a certain speed into the gap between the welded sheets 2. The arcs 3 are lit on a special insert 4, inserted into the groove edges at the beginning of the seam. Due to the joint melting of the electrodes and the edges being welded, a welding bath is formed 5i Transverse non-uniform magnetic field A field in the weld pool zone is created by a U-shaped electromagnet b. The topography of the magnetic field in the weld pool is determined by the design of the electromagnet and the properties of the evariable metal. If the evariated metal has ferromagnetic properties, then the topography of mag-. The nitric flux in the weld gap and the weld pool depends on the geometry of the edge grooves, which in this case are the poles of the electromagnet, and the shape of the thermal surface with the Curie point temperature. In this case, the required gradient of the magnetic induction over the depth of the weld is obtained by choosing the bevel angle of the edges of the welding joint with the succession of their uniform melting. The dependence of the gradient of the magnetic iDU1QJY on the angle of the bevel of the edges can be obtained experimentally. When welding steel sheets in the lower position, the required gradient of magnetic induction is achieved by creating a bevel angle t of the edges 22-26 on the front side of the joint, and when welding in the ground position, by creating that coherence angle but from the back side of the joint. When welding non-ferromagnetic materials, the topography of the -functional yogic floor is determined by the design and location of the electromagnet relative to the weld pool and does not depend on the geometry of the groove. The strength of the weld pool is held by mechanical fbrim devices - a sliding coolant with each slider 7 forming the face of the joint surface and the lining 8 of the top of the seam surface. To ensure the stable formation of the weld pool, it is resistant against accidental disruption of its equilibrium. A transverse magic box is used with a magnetic induction increasing at the surface of the weld pool. In this case, due to the disturbance of the balance between the forming forces and the hydrostatic pressure of the weld pool, the liquid metal begins to move in the direction of increasing the magnetic induction, which leads to an increase in the ponderomotive

formative forces and recovery. equilibrium weld pool.

This magnetic field characteristic can be provided by both the design of the electromagnet and its location relative to the weld pool.

To implement the described welding method, it is advisable to use arc welding in protective gas or flux-cored welding.

An example of the method described is the welding of two steel sheets 30 mm thick in the ceiling positions.

Welding is carried out in one pass by two pores with dkamer wire with a diameter of 4 gF1, connected to different polarities, with the forced formation of a seam {Fig. four).

The seam is formed by a sliding cooled slider 7 on the front side of the joint and the lining 8 or the second slider on the reverse side of the joint.

Two electrode wires are fed into the space, formed by forming devices and edges of the sheets to be welded. The distance between the electrodes (arcs 3) is set to the maximum possible within the range of the metal to be welded, but in such a way as to exclude the melting of the surface of the forming devices. In practice, the distance between arcs can be determined by the dependencies:

e & - 2,

where B is the distance between arcs;

b - thickness of the metal being welded

 r is the radius of the arc column.

When welding steel with a thickness of 30 mm, this distance is 24-25 mm.

Taking into account that in this example the ferromagnetic material is welded, the shape of the isotherm of the near-surface zone with the temperature of the Curie point is of fundamental importance.

To hold the welding bath in a ceiling position, it is not necessary that the isotherm lines on either side of the seam be at an angle of 22-26, pointing upwards.

This arrangement of the isotherms is achieved by setting the corresponding voltages on the arcs:.

-.on the arc located at the front of the forming device - 3032 V, and on the second arc - 35-36 V. Obtaining the desired angle between the isotherms with the temperature of the Curie point

suitable cutting of edges also contributes.

Welding is performed on:

wire feed speed 260280 m / h;

welding current 800-900 A;

voltage on arcs 30-32 V

and 35-36 V.

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The welding speed in this case is determined by the deposition rate and is the value derived from the feed rate of the electrodes (in our example, 7-8 m / h).

In the proposed welding method, the main parameters of the mode, besides the indicated ones, also include magnetic induction of the transverse magnetic field created by the electromagnetic attachment.

Considering that the transverse magnetic field in the butt gap is | Non-one-dimensional, the maximum magnitude of the magnetic induction, determined when the sensor is moved according to the depth of cutting, is taken as reference.

5 edges.

in this case, the magnitude of the magnetic induction should be 200-250 Gs, and its direction should be set. by the well-known rule

0 of the left hand so that the interaction of the field and the current in the liquid metal creates a ponderomotive force directed to the front of the weld pool.

five

The holding of the weld pool during this, besides the mechanical forming devices, is provided by compensating the hydrostatic pressure of the liquid metal due to

0 creating an appropriate gradient. Magnetic induction, increasing to the root of the seam.

The sharing of mechanical devices and electromagnetic

5 forces to form a seam allows to significantly increase the critical mass of the weld pool held in different spatial positions, and this allows you to increase

0 the critical value of the welding current and the performance of the process as a whole. For example, the known methods of welding ensure the formation of a seam V. The overhead position on currents up to 150-200 A.

five

At the same time, surfacing capacity is up to 4 kg / h.

The proposed welding method involves the implementation of the process on currents up to 800-1000 A and provides

0 surfacing performance more than 30 kg / h. the productivity of the process is increased several times.

In addition, the proposed method i

5 provides for welding one-pass thick plate rolling through the compensation of hydrostatic pressure of the liquid metal, which contributes to the reduction of preparatory

0 and intermediate operations (hardware setup, slag removal after each pass, etc.).

Claims (1)

Claim 1. Arc welding method with forced seam formation, with