RU2309031C2 - Method for forming welded joints of sheet metallic materials - Google Patents

Abstract

FIELD: manufacture by HF-welding of different thin-wall complex-shape articles, for example envelope parts.

SUBSTANCE: method comprises steps of placing welded blanks to action zone of magnetic inductor connected to magnetic pulse generator; restricting parts at side opposite to magnetic inductor by means of rigid support of insulation material; forming notches on welded surfaces of parts; overlapping welded surfaces one to other with overlapping zone exceeding value of notches; forcing welded surfaces of blanks one to other and to rigid support by efforts caused by interaction of magnetic fields of inductor and self-induced current occurred in blanks and heating them in welding places; realizing common fusion of blanks.

EFFECT: enhanced stability of welding process not needing complex mechanical attachments and large amount of energy.

4 dwg

Description

The present invention relates to the field of high-frequency welding and can be used in the manufacture of various thin-walled products, in particular shell parts.

The famous "Welding of the metal sheaths of electric cables", A.N. Shamov, I.V. Lunin, V.N. Ivanov, "High-frequency welding of metals", L .: Engineering, 1977, pp. 144-155, Fig. 94, in which the metal tape is initially bent, acquiring a trough-like shape, and then rolled up into a cylindrical pipe with a straight convergence of the butt edges.

In this way, it is difficult to weld products of finite length, since unevaled sections at the beginning and end of the weld are inevitable, and products of complex configuration due to the peculiarities of current supply systems and upsetting mechanisms. This method does not allow lap welding, and when butt welding, there is a limitation of the surfaces to be welded along the thickness in the direction of reduction.

The famous "Welding of steel thin-walled spiral-seam pipes", A.N. Shamov, I.V. Lunin, V.N. Ivanov, "High-frequency welding of metals", L .: Engineering, 1977, pp. 170-178, Fig. 105, in which the surfaces to be welded are pressed against each other by additional devices on both sides, the welding is overlapped with a contact current supply.

This method also has several disadvantages. Firstly, the quality of the joint depends on the geometry of the welded edges in the heating and upsetting section, secondly, a series of pulses heats the metal in volume more than the volume of the molten metal, which accordingly requires large energy expenditures, and thirdly, for pressing the edges to each other a friend needs an additional (mechanical) device and, fourthly, the heating zone is oxidized.

Closest to the proposed invention is the "Method for producing welded joints of sheet metal materials", according to patent No. 2110381, BK 13/01, in which the welded workpieces are placed in the zone of action of a magnetic inductor connected to a high-frequency current source, and from the side opposite to the magnetic inductor the workpieces are limited by a rigid support of insulating material.

This method eliminates the disadvantages of the above methods, but does not ensure the stability of the welding process when receiving welded shells of complex shape, which is caused by the complexity of the behavior of the edges at the time of the pulse current. One of the main reasons for obtaining a joint of unsatisfactory quality during lap welding is the presence of a gap between the welded edges of the workpiece at the moment of passage of the pulse current through the inductor. As a result, the current of the magnetic fields of the inductor does not pass along the edge closest to the inductor, and therefore, electromagnetic forces do not act on this edge, pressing the workpiece to a rigid support, which in turn sharply reduces the area of the welded section in the overlap zone.

If the overlap zone is clamped to a rigid support before the pulse current passes, then the contact resistance will sharply decrease, and more energy will be required for welding (a large pulse current), which can destroy a thin-walled workpiece.

Another way to remove the gap between the edges of the workpiece at the moment of passing the pulse current through the inductor is to increase the overlap zone by two times or more, but also lead to a sharp drop in contact resistance.

The objective of the invention is to ensure the stability of the welding process when receiving welded thin-walled shells of complex shape.

The problem is solved in that when implementing the proposed method for producing welded joints of sheet metal materials, the welded workpieces are placed in the zone of action of the inductor connected to the magnetic pulse generator, and from the side opposite to the inductor, they are limited by a rigid support of insulating material, the welded surfaces of the workpieces are pressed one to another and to a rigid support by the forces of the interaction of the magnetic field of the inductor and the pulses of the self-induction current arising in the workpieces and heating ayuschego them in places of welds, the welding surfaces on workpieces operate embossments weldable surfaces are superimposed to form overlap zones greater than the depth of embossments, and produce their joint fusion.

Figure 1 shows the workpieces proposed for welding by this method, figure 2 is a welding diagram; figure 3 - embodiments of perforations on the welded surfaces; figure 4 is an example of the implementation of notches.

Work with the proposed method is as follows.

The welded surface of the workpiece 1 is connected so that the edges 2 are facing each other. The overlap zone, at a minimum, should provide overlapping of the cutouts 3 located at the edges 2. Moreover, the blank 1 has an open loop, because edges 2 do not press against each other mechanically.

An inductor 5 is connected to the magnetic pulse generator 4, which creates a high-frequency magnetic field. Under the influence of this magnetic field, the edges 2 are attracted to each other, forming a closed loop of the workpiece 1, in which a large self-induction current pulse is induced.

When the electromagnetic fields of the inductor 5 and the self-induction current of the workpiece 1 interact, forces arise that deform the workpiece 1 in the direction from the inductor 5 to the workpiece 1. To prevent this deformation from the workpiece 1, opposite the induction, a rigid support of insulating material 6 is installed.

Under the action of a self-induction current, at the junction of the edges 2 of the workpiece 1, which has increased contact resistance, zones of heating of the material are formed. When passing through the cuts 3, sharp jumps in resistance are created in the circumferential direction (along the induced current path), which leads to the creation of additional foci of melting the material. After cooling the workpiece 1, a reliable lap weld is formed.

Consider an example in which a blank of complex shape made of aluminum foil, 0.15 mm thick, is welded. The notches are made in the form of a “dovetail”, the depth of the notches is 1.5–2 mm, the width of the smaller side is 4–5 mm, and the inclination angle is 30–40 °.

To ensure welding, a multi-start multi-turn cone-shaped internal inductor was used, which is powered by an industrial generator with a maximum stored energy of 2.5 kJ (type GIT2-2-01 of the Impulse series). To ensure welding, a stored energy of several joules (5 ÷ 10 J) was required.

A single impulse passes from the generator. The presence of slots allows you to eliminate the gap between the edges of the workpiece, since the edges of the workpieces are attracted to each other and to the support. When passing through the cuts, jumps in resistance occur, the material melts, and a reliable welded joint is formed.

The whole welding process takes place in fractions of a second, so this method allows you to weld thin-walled metals, both ferrous and non-ferrous, and also does not require complex mechanical devices and high energy costs.

Claims (1)

A method of producing welded joints of sheet metal materials, in which the workpieces to be welded are placed in the range of the inductor connected to the magnetic pulse generator, and from the side opposite to the inductor, they are limited by a rigid support made of insulating material, while the welded surfaces of the workpieces are pressed one against the other and against the rigid support by the forces of interaction of the magnetic field of the inductor and the pulses of the self-induction current that occurs in the workpieces and heats them in the places of welding, characterized in that The welded surfaces of the workpieces perform grooves, the welded surfaces are superimposed on each other with the formation of an overlap zone greater than the depth of the grooves, and they are fused together.

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