JPH04157078A - Laser beam welding method - Google Patents

Abstract

PURPOSE:To obtain a uniform and stable weld bead excellent in wettability by fitting an electromagnetic coil right above a molten pool, generating an alternating magnetic field and stirring the molten pool forcibly. CONSTITUTION:An electric current is sent between a welding wire 3 and base metals 18 to be welded from a wire heating power source 6 via a wire heating feeder 6' and the welding wire 3 is heated by Joule heat of I<2>R. The wire feed quantity in the wide range can be used by such welding heating and in order to obtain greater stability and the uniform weld bead excellent in wettability at the same time, the electromagnetic coil 10 formed into a hollow shape so as not to obstruct an optical path of a laser beam 1 is fitted right above the molten pool and electricity is supplied to generate the alternating magnetic field to the electromagnetic coil 10 to this via an electromagnetic coil feeder 12 and the molten pool is stirred forcibly by adding the alternating magnetic field.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a laser welding method.

[Conventional technology]

Conventionally, in laser welding performed with the addition of a welding wire, as shown in the vertical cross-sectional view of FIG. The feed roller 4 forms a feed nozzle 8 there.
A method is used in which the welding wire 3 fed through the welding wire is fed and welding is performed. Here, 21 is a fixed tip of the feeding nozzle 8, and 7 is a gas inlet for protecting the lens and using it as a shielding gas.

[Problem to be solved by the invention]

By the way, during laser welding, welding is performed by setting the feeding position of the welding wire 3 to the optical axis of the laser beam 1 and the width center of the molten pool 26 in the welding direction (hereinafter referred to as the "target position"). When the welding wire 3 is slightly detached from the molten pool 26, the welding wire 3 is split into two by the laser beam 1, and welding does not occur even if the welding wire 3 reaches the rear of the molten pool 26, as shown in the perspective view of FIG. occurs. Furthermore, even if the welding wire 3 is fed into the molten pool 26, if the aiming position deviates even slightly, the weld bead will become lopsided 22 and fall into the next layer bead 24, as shown in the cross-sectional view of FIG. 5(A). have a negative impact.

Even if the target position is accurate, if the relationship between the welding speed and the welding wire feed rate is poor, a convex bead 23 as shown in FIG. It becomes difficult to set an appropriate amount of welding focus blur, and this causes a change in welding output, resulting in unstable welding. Here, 8 is a feed nozzle, 18 is a welding base material, and 25 is a defect such as poor fusion that occurs during lamination.

The present invention was proposed in view of the above circumstances, and is capable of manual welding wire feeding over a wide range of areas.

The object of the present invention is to provide a laser welding method that enables continuous, uniform, and flat welds with good wettability.

[Means to solve the problem]

To this end, the present invention focuses a laser beam through a condensing lens and performs welding by adding a welding wire, in which the wire is heated using Joule heat of I'H and an alternating magnetic field is applied to the molten pool. It is characterized by welding while melting and stirring.

[Effect]

According to such a welding method, the target position of the added welding wire tends to shift intermittently and the molten pool 2611! The unstable weld bead forming factors caused by desorption etc. can be removed by heating the welding wire and stirring the molten pool in an alternating magnetic field by the electromagnetic coil 10.

When the welding wire is heated when it leaves the molten pool in a cold state, it is divided into two by the extremely small diameter laser beam 1 focused through the condenser lens 2 and separated in different directions, resulting in non-welding. In this case, when the welding wire is fed into the molten pool in advance, a current is passed between the welding base metal, and the Joule heat that resides there is used to constantly supply the welding wire in a heated state to perform welding, and if H desorption occurs from the molten pool. , it melts even when it comes into contact with the laser beam 1 or within the plasma (including plume) generated when the base material is melted, resulting in stable welding, making it possible to use a wide range of wire feed rates.

In addition, when welding with a focused laser beam, the energy density is high, so deep penetration can be achieved with a small weld pool, but when welding with the addition of welding wire, the molten pool is small and melts and solidifies quickly. Therefore, when the welding wire is fed into the molten pool, it will solidify without being sufficiently stirred after being melted by the laser beam, so if the aiming position and direction of the welding wire are not ensured, the welding bead 22 will be uneven.
Inherent defects 25 such as poor fusion occur in the next layer bead 24.

In order to prevent these problems, in the method of the present invention, a 1° electromagnetic coil is installed directly above the molten pool so as not to obstruct the laser beam path, and an alternating magnetic field is generated to forcibly stir the molten pool. This results in a stable weld bead that is uniform and has good wettability.

In this way, by employing alternating magnetic field forced stirring using an electromagnetic coil to heat the welding wire, a continuous and stable weld bead can be obtained, and it becomes easy to set the appropriate welding focus blur amount most necessary for laser welding.

〔Example〕

One embodiment of the present invention will be explained with reference to the drawings.
In the figure, when a laser beam 1 is focused by a condensing lens 2 and irradiated onto a welding base material 18 for welding, a welding wire 3 is sent out by a feeding roller 4 and fed through a feeding nozzle 8 at an appropriate target position. do.

At that time, in order to stably feed the welding wire 3, a current is passed between the welding wire 3 and the welding base metal IB from the wire heating power source 6 through the wire heating power supply 16°, and the welding wire 3 is
! -Heat using the Joule heat of R. welding wire 3
The welding wire 3 and the feeding nozzle 8 are insulated from others by a nozzle insulating tip 9.

Such welding wire heating allows the use of a wide range of wire feed rates to obtain better stability and at the same time obstruct the optical path of the laser beam 1 in order to obtain a uniform weld bead with good wetting properties. A hollow electromagnetic coil 10 is installed directly above the molten pool, and power is supplied to the electromagnetic coil 10 to generate an alternating magnetic field via an electromagnetic coil power supply line 12. Perform forced stirring.

Here, the electromagnetic coil 10 is adjacent to high-temperature parts such as the molten pool 26 and the laser beam 1, and also generates heat by itself, so the electromagnetic coil cooling water supply pipe 14. Electromagnetic coil cooling pipe 13. It is cooled by a water cooling mechanism consisting of an electromagnetic coil cooling water discharge pipe 15. A shield box 11 is provided to house these, and a shield gas inlet 16 is installed in this box in addition to a lens gas (used to protect the lens and as a shield gas) feed lower, and a sintering port 16 is installed to make the shield gas a trickle. The shielding effect is improved by employing the bonded metal plate 17 and controlling the lens gas shielding gas separately. Each of these parts and mechanical parts are located in the lens case 19.
Attachment is performed by welding in conjunction with the optical axis of laser beam 1.

Figure 2 shows a modification of Figure 1, and in narrow gap welding, pipe welding, fillet welding, etc., when the distance between the electromagnetic coil 10 and the welding surface * is adjusted and the shape of the electromagnetic coil is changed, etc. The installation of the electromagnetic coil 10 of an appropriate shape and the distance adjustment are performed using the mechanism 20, and the electromagnetic coil is moved up and down according to the amount of defocus, and the strong stirring of the molten pool 26 is controlled by electrical external control and position. By performing both physical control and control, the scope of coverage can be further expanded.

〔Effect of the invention〕

According to this welding method, by heating the welding wire, stable welding wire feeding over a wide range is possible, a continuous and well-proportioned weld bead can be obtained, and an alternating magnetic field is applied to the molten pool at tT11. Adding the weld using a coil and vigorous stirring ensures a flat welding bead with good wettability, prevents poor fusion due to multi-layer build-up, and also lifts inherent defects such as porosity, resulting in a stable and stable welding process. Good quality welded joints can be obtained.

In short, according to the present invention, in welding performed by focusing a laser beam through a condensing lens and adding a welding wire,
By heating the wire using I"H Joule heat and welding while melting and stirring by applying an alternating magnetic field to the molten pool, it is possible to feed the welding wire continuously and evenly over a wide range. The present invention is industrially extremely useful because it provides a laser welding method that provides a flat weld bead with good wettability.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing a modification of FIG. 1. Fig. 3 is a longitudinal sectional view showing a known laser welding method;
This figure is a perspective view showing a welding wire in the welding shown in FIG. 3, and FIG. 5 is a sectional view of a welded part showing welding defects by a conventional method. DESCRIPTION OF SYMBOLS 1...Laser light, 2...Condensing lens, 3...Welding wire, 4...Feeding roller, 5...Power feeding tip, 6...Wire heating power source, 6゛... Wire heating power supply line, 7... Lens gas inlet, 8... Feeding nozzle,
9... Nozzle insulation chip, 10... Electromagnetic coil, 1
DESCRIPTION OF SYMBOLS 1... Shield box, 12... Electromagnetic coil power supply line, I3... Electromagnetic coil cooling pipe, 14... Electromagnetic coil cooling water supply pipe, 15... Electromagnetic coil cooling water discharge pipe,
16... Shield gas inlet, 17... Sintered metal plate, 18... Base material, 19... Lens case, 20...
・Electromagnetic coil mounting mechanism, 21...Fixed chip, 22・
... Offset heat, 23 ... Convex bead, 24 ... Next layer bead, 25 ... Defect, 26 ... Molten pool, 27.
...Welding Bead, Agent: Masa Tsukamoto, Patent Attorney Figure 2, Figure 3, Figure 4

Claims (1)

[Claims] In welding, which is performed by focusing laser light through a condensing lens and adding welding wire, the wire is heated using I^2R Joule heat, and an alternating magnetic field is applied to the molten pool to melt and stir it while welding. A laser welding method characterized by: