RU2740937C1 - Method for point magnetic-pulse welding of flat sheet metal materials and device for implementation thereof - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention can be used in point magnetic-pulse welding of sheet metal materials. Upper and lower parts to be welded are arranged on support, which is made with through hole. In lower part in each point of welded connection there made is conical hole, base of which is turned towards surface of upper part. Parts are placed with alignment of conical hole of lower part with through hole in support and axis of symmetry of U-shaped welding inductor. Welding inductor is fixed in high-current feeder and connected to source of pulse current. Inductor is equipped with an insulator on its central part designed to exclude electric contact when placing the inductor top over the welded parts.

EFFECT: technical result of disclosed invention is expansion of technological capabilities of magnetic-pulse plants.

2 cl, 3 dwg

Description

Technology area

The invention relates to the field of metal forming by pressure, namely to the magnetic-pulse spot welding of sheet metal materials and can be used in various fields of mechanical engineering, instrument making, in aviation and rocketry.

State of the art

The method of magnetic pulse welding is a logical development of explosion welding, in which one of the parts to be welded is accelerated relative to the other due to the energy of the explosive. During high-speed collision of parts at certain angles, a welded joint is formed between them. In magnetic pulse welding, one of the parts is accelerated by a pulsed magnetic field. The method of magnetic pulse welding is described in US Patent No. 3520049, UK Patent No. 755472, and in "Magnetic-pulse welding of metals" Dudin AA, M .: Metallurgy, 1979, p. 128 p. This method is used mainly for tubular parts when using single or multi-turn solenoids as welding inductors.

From the prior art, US patent No. US3851139 "MAGNETIC PULSE WELDING USING SPACED PROXIMITY CONDUCTOR" is known, which describes a method and device for magnetic-pulse welding of a pair of electrically conductive flat workpieces, consisting of power supplies, switches and inductors of various configurations. The disadvantages of this solution are that an additional power source is required to provide preheating, and the dimensions of the workpieces to be joined are limited by the geometric dimensions of the inductor.

In the source Racineux G., Manogaran A., Pereira D., Miranda R.M. (2014) Dissimilar Welding Using Spot Magnetic Pulse Welding. In: Xu J., Cruz-Machado V., Lev B., Nickel S. (eds) Proceedings of the Eighth International Conference on Management Science and Engineering Management. Advances in Intelligent Systems and Computing, vol 280. Springer, Berlin, Heidelberg, describes magnetic pulse spot welding of dissimilar materials. The installation included a bank of capacitors with a maximum stored energy of 30 kJ. The welding inductor had a flat configuration. Magnetic-pulse spot welding of a pair of aluminum - steel was carried out and the analysis of the resulting welded joints was carried out. The disadvantages of the proposed solution is that in order to provide the required gap between the parts to be welded, a preliminary deformation of one of them was made, which, on the one hand, complicates the technological process, and on the other hand, increases the risk of material destruction in the places of preliminary bends. Also, the disadvantages of the described circuit can be attributed to the flat configuration of the inductor, since in such a circuit it is difficult to provide the required mechanical strength.

In US patent No. US 9636771, taken as a prototype, a device for magnetic pulse welding of flat metal strips is described. The device consists of an electric current source, a connecting feeder and welding inductors of various configurations. The disadvantage of this device is the impossibility of welding sheet parts of large size and arbitrary configuration.

Disclosure of the invention The technical problem to be solved by the claimed technical solution is the expansion of the technological capabilities of magnetic-pulse installations, namely, the implementation of an inseparable connection of two extended sheet parts, including those made of dissimilar materials.

The technical result of the claimed invention is that a U-shaped configuration of the welding inductor is used, located above the parts to be welded, and the method of magnetic-pulse welding includes the preparation of the materials to be welded and the formation of a number of circular welded joints.

The technical result of the claimed invention is achieved by the fact that: a method is proposed for producing joints of flat sheet metal materials by spot magnetic pulse welding, which includes placing the upper and lower parts to be welded on the stop under the inductor and the implementation of spot magnetic pulse welding, while the stop is made with a through hole, when This uses a U-shaped welding inductor, which is installed with a minimum gap between its top and the parts to be welded, and a tapered hole is made in the lower part at each intended point of formation of a welded joint and the parts are placed with the alignment of the tapered hole of the lower part with a through hole in the stop and with the axis of symmetry of the U-shaped welding inductor, while the base of the cone of the hole of the lower part faces the surface of the upper part.

Also proposed is a device for obtaining joints of flat sheet metal materials by spot magnetic-pulse welding, containing a welding inductor fixed in a high-current feeder, a pulse current source, a control device and an emphasis for placing parts, while the welding inductor has a U-shape and is equipped with an insulator on its central part, designed to exclude electrical contact of the inductor when placing its apex above the parts to be welded, and the inductor is connected to a pulsed current source through a high-current feeder, and the stop is made with a through hole, allowing it to be displaced with the axis of symmetry of the U-shaped welding inductor.

The combination of the above essential features leads to the fact that:

- As a result of the current pulse flowing through the U-shaped inductor, the maximum current density is reached at the point of the minimum gap formed by the outer top of the U-shaped inductor and the parts to be welded;

- Welded joints of extended sheet electrically conductive materials (or having a curvature, the radius of which is much larger than the dimensions of the inductor) are obtained;

- The geometrical dimensions of the parts to be welded are not limited by the size of the welding inductor.

Brief Description of Drawings

The essence of the invention is illustrated by the figures.

FIG. 1 shows a general diagram of a magnetic pulse installation for magnetic pulse spot welding of flat sheet metal materials, where:

1 - U-shaped welding inductor

2 - parts to be welded

3 - stop

5 - inductor insulator

6 - insulating sleeves

7 - high current feeder

8 - compensation hole

9 - fixing and feeding device

10 - pulse current source

11 - frame

12 - dielectric plate

13 - control device.

FIG. 2 and FIG. 3 shows, on an enlarged scale, the formation of a circular welded joint when a current pulse flows through an inductor, where:

1 - part of the welding inductor,

2 - parts to be welded,

3 - emphasis,

4 - the place of formation of a circular welded joint,

5 - inductor insulator.

Implementation of the invention

The magnetic pulse spot welding apparatus shown in FIG. 1, includes a metal frame 11 (partially shown in the drawing), on which a high-current feeder 7 is fixed with bolted connections through insulating bushings 6, consisting of two massive parts, electrically isolated from each other by a dielectric plate 12 held in a gap, for example , friction. A U-shaped welding inductor 1 is attached to the high-current feeder 7, fixed in a high-current feeder, for example, on a tapered fit with a threaded fixation, the method of fixing the inductor should provide electrical contact between the latter and the high-current feeder, and also ensure the ability to withstand significant mechanical forces. An insulator 5 is fixed on the welding inductor 1, designed to exclude electrical contact of the inductor with the parts to be welded. Welding inductor 1 through a high-current feeder 7 is connected to a pulsed current source 10. The parameters of the pulsed welding current are determined by the control device 13. The welded parts 2 are located between the inductor 1 and the stop 3, while the lower part must be prepared in advance. Preparation consists in creating a tapered hole at each intended point of formation of a welded joint. The base of the cone should face the top surface. The angle between the base of the cone and its generatrix is determined from the conditions of weldability of various materials (Journal of Atomic Energy, vol. 73, issue 4, October 1992 pp. 278-284. And "Investigation of magnetic-pulse welding in plane geometry", M.N. Kazeev, VS Koydan, VF Kozlov, Yu.S. Tolstov. Applied Mechanics and Technical Physics, 2013, 6, pp. 38-44). The massive stop 3 is fixed to the frame (not shown in the drawing) and has a through hole 8. The stop is designed to hold the parts relative to the welding inductor and compensate for the forces arising during welding. The hole 8 excludes the formation of back pressure of the air flowing out during the movement of the upper sheet surface. The fixing and feeding device 9 is intended for positioning the parts to be welded relative to the welded inductor, holding them at the moment of welding and moving the parts to the next welding point.The fixing and feeding device 9 can be controlled both in manual and automatic modes and must ensure the coincidence of the symmetry axes of the welding inductor 1 and a tapered hole in the bottom welded part.

A possible material for the insulator of the inductor 5 is a fluoroplastic, with a thickness of about 1 mm. its presence is due to the technological gap, which excludes the electrical contact of the inductor 1 and the parts to be welded 2. The resulting pulsed magnetic pressure, maximum in the region at the point of the outer vertex of the U-shaped welding inductor 1, accelerates part of the upper part 2 in the direction of the lower one, upon collision of which an annular continuous compound.

The installation (device) works as follows: The welded sheet metal parts 2 are placed between the welding inductor 1 and the stop 3, while the fixing and feeding device, under the control of the operator or automatically, positions the parts to be welded to one of the points of the proposed welding. At this point, the center of the tapered hole prepared in the lower workpiece to be welded should be aligned with the axis of symmetry of the welding inductor 1, while ensuring that the minimum gap between the inductor and the workpieces to be welded is located exactly above the center of the prepared tapered hole. After that, the control device 13 initiates a pulse from the pulsed current source 10. The shape, amplitude and duration of the pulsed welding current depend on the characteristics of the materials to be welded and are determined by the control device 13. When current flows through the inductor 1, the current density in the cross section is not uniform. The highest current density is formed near the gap between the welding inductor 1 and the upper part to be welded. This is because in this configuration, an electrically conducting plane near a conductor with a current is a concentrator of the magnetic flux (Knopfel G. Superstrong pulsed magnetic fields. Generation methods and physical effects associated with the creation of pulsed fields of the mega-Oersted range, translated from English by F.A. Nikolaev and Yu.P. Sviridenko. - Moscow: Mir, 1972. - 391 p.) As a result, in the area of the minimum gap between the welding inductor 1 and the upper part 2, a magnetic pressure pulse arises, accelerating the part of the upper welded part in the direction of the lower welded part. Accelerated to the speed required for the formation of a welded joint, a part of the upper of the surfaces to be welded collides with the lower surface in the region of the prepared tapered hole and they are welded. FIG. 2 shows on an enlarged scale the cross-sections of the sheets to be welded at one of the welding points before the flow of the pulsed welding current. FIG. 3 - after the flow of a pulsed welding current and the formation of a welded joint. FIG. 3, the zone of the formed welded joint 4 is an annular region located on the side surface of the previously prepared tapered hole.

Thus, the claimed invention solves the following main problem: it performs spot magnetic pulse welding of flat metal sheets of large size (including dissimilar materials) or having a radius of curvature several times greater than the linear extent of the welded joint zone.

Claims (2)

1. A method of obtaining joints of flat sheet metal materials by spot magnetic-pulse welding, including the placement of the upper and lower parts to be welded on the stop under the inductor and the implementation of spot magnetic-pulse welding, characterized in that the stop is made with a through hole, while using a U-shaped a welding inductor, which is installed with a minimum gap between its top and the parts to be welded, and a tapered hole is made in the lower part at each assumed point of formation of the welded joint and the parts are placed with the alignment of the tapered hole of the lower part with the through hole in the stop and with the axis of symmetry of the U-shaped welding inductor, with the base of the cone of the hole of the lower part facing the surface of the upper part. 2. A device for obtaining joints of flat sheet metal materials by spot magnetic-pulse welding, containing a welding inductor fixed in a high-current feeder, a pulse current source, a control device and an emphasis for placing parts, characterized in that the welding inductor has a U-shape and is equipped with an insulator on its central part, designed to exclude electrical contact of the inductor when placing its apex above the parts to be welded, and the inductor is connected to a pulsed current source through a high-current feeder, and the stop is made with a through hole that allows it to be aligned with the axis of symmetry of the U-shaped welding inductor ...

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