JPH02117782A - Method for welding t-joint by electron beam welding - Google Patents

Abstract

PURPOSE:To prevent the occurrence of spike defects and to improve quality by irradiating metal plates with electron beam at the same time from both sides of a web and integrating molten metal pools formed by irradiation of the respective electron beam. CONSTITUTION:A flange 1 and the web 2 are formed in a T-shape by two metal plates and the electron beam irradiates at the same time from both sides of the web 2 and crossing of the formed molten metal pools is integrated. As a result, the width of the tip of penetration can be extended by synergism of the electron beam 3 from the respective sides and the spike defects can be prevented. Further, narrowing of the penetration width can be reduced by effect of electron beam energy from the facing sides which is effective for preventing the generation of lack of fusion.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of welding metal T- or H-shaped joints by electron beam welding.

BACKGROUND OF THE INVENTION In recent years, the use of electron beam welding for welding metals such as steel has expanded. This is because electron beam welding requires almost no welding auxiliary materials, has a much higher energy density than other welding methods such as arc welding, can easily weld even thick materials, has small welding strain, and This is thought to be due to the fact that it is possible to weld by electron beam irradiation from a certain position, and it is possible to weld even in narrow deep areas.

However, electron beam welding also has its disadvantages.For example, the electron beam is curved by magnetism, so when welding magnetized materials such as steel, the residual magnetism in the welding material causes the electron beam to be biased, causing it to reach the desired position. Welding may become impossible. On the other hand, electron beam irradiation is linear, and it is very difficult to irradiate with a curved shape. Therefore, when attempting to electron beam weld a T-shaped joint in which a flange 1 and a web 2 are brought together as shown in FIG. 2, if the electron beam is irradiated parallel to the flange, the flange surface will be damaged and welding will not be possible.

Therefore, JP-A-58-18888, JP-A-48-4
Various methods are shown in Publication No. 5448, etc.0 For example, as shown in Figure 5, a method in which an electron beam is irradiated diagonally from above to weld one side, and then the other is irradiated diagonally from above to weld. As shown in FIG. 3, there is a method of attaching a convex portion 5 to the flange to prevent damage to the flange by the electron beam, and as shown in FIG. 4, welding is performed by irradiating the flange with an electron beam from the back side.

However, these methods also have advantages and disadvantages. In the method of welding from above diagonally as shown in FIG. 5, pores called spike defects 6 are generated in each weld, so there are many restrictions on welding conditions and applicable materials. This spike defect is a defect characteristically occurring in electron beam welding. In electron beam welding, melting occurs when irradiated with an electron beam, and a keyhole is formed by the force of the gas components generated at this time. This keyhole moves as the electron beam moves. On the other hand, the molten metal flows into the previously formed keyhole, solidifies, and welding progresses.

At this time, the tip of the keyhole is narrow and sharp, gas is present, or the solidification rate is fast, so molten metal does not flow sufficiently and pores are generated. This is called a spike defect.

By devising a construction method, the spike defects on the side to be welded first in FIG. 5 can be remelted by the electron beam from the side to be welded later, thereby preventing spike defects. However, spike defects are formed again at later welded locations. For this reason, methods for preventing spike defects have been proposed, such as vibrating an electron beam with a large amplitude, but increasing the amplitude of the electron beam deteriorates the appearance of the bead. Further, even with this method, there is a problem that pores cannot be completely prevented.

On the other hand, in order to prevent spike defects, there is a method of attaching a convex portion 5 to the flange as shown in FIG. 3 to enable penetration welding.

However, if the convex part is too small, the beam will be bent due to the influence of magnetism from the flange surface, so the convex part must have a certain height depending on the size of the flange, the amount of residual magnetism, etc., and this convex part is the target. It is expensive because it requires cutting from a thicker plate or rolling it during the manufacture of the plate.

In addition, when welding from the back side of the flange shown in Figure 4, the welding width of the electron beam is small, so in order to completely weld thick Ukobu material, multiple bus welds must be performed, and if the flange is thick, the flange must be melted. lose a lot of energy.

Problems to be Solved by the Invention As mentioned above, many proposals have been made to solve various problems when welding T-joints using electron beam welding, but there are still many proposals for welding T-joints using electron beam welding. There are various problems when applying this method to T-type welding of large materials. This is especially a big problem when welding large T-shaped welds with a plate thickness exceeding 30 mm.

When electron beams are irradiated separately from diagonally above in FIG. 5, the spike defects described above are more likely to occur.

Machining the convex portion shown in FIG. 3 requires a large increase in cost, and welding from the back side of the flange shown in FIG. 4 requires several passes or more. In contrast, the present invention prevents the occurrence of spike defects, eliminates the need for protrusions during temporary assembly, and realizes high-quality, economical welding of T-shaped joints.

Means for Solving the Problems The gist of the present invention is that in welding a T-shaped joint by electron beam welding, an electron beam generator is round-necked on both sides of the web, and electron beams are irradiated from both sides of the web at the same time. T by electron beam welding characterized by the intersection of the tips of the molten metal pool formed by beam irradiation
It is in the welding method of type joints. Note that the T-type joint in the present invention includes an H-type joint.5 As shown in FIG.
and an electron beam 3 is emitted from both sides of the web.
irradiate and weld at the same time. As mentioned above, if the electron beam is irradiated to one side after solidifying the other, there are problems such as the occurrence of spike defects. As mentioned above, spike defects are caused by narrow and sharp weld penetration tips. Therefore, if electron beams are irradiated from both directions at the same time, and the pools of molten metal formed by each electron beam intersect and become unified, the synergistic effect of the electron beams from each will widen the width of the melting tip. can do. Further, since molten metal flows from both sides, spike defects can be prevented.

Furthermore, according to this method, fusion failure 7 as shown in FIG.
It is also effective in preventing. Electron beam welding is originally characterized by a narrow penetration width, but the deeper the penetration from the surface, the more energy is consumed, so the width tends to become narrower. For this reason, if the beam is irradiated obliquely to the open beam, poor fusion 7 will likely occur as shown in Figure 5.On the other hand, if the electron beam is irradiated from both sides simultaneously, the effect of the electron beam energy from the opposite side will It is possible to reduce the narrowing of the welding width, which is effective in preventing the occurrence of fusion defects.

The relationship is between the respective electron beam irradiation positions.

In order for the tips of both molten metal pools to intersect, the molten metal pool in electron beam welding may be small, within 20 mm in the direction of welding progress, and within 5 mm in the direction perpendicular to welding.
It is necessary to irradiate from both sides within a range of mm. However, this range is greatly influenced by electron beam irradiation conditions, heat input conditions such as movement speed. If the heat input is high, the possible range becomes large, and if the heat input per person is small, the possible range becomes small.

In addition, the direction of irradiation should be slightly in front or behind the direction of welding progress.The electron beam has a high penetrating power, so if there is a locally large gap, the electron beam may penetrate the workpiece. It is also possible to damage the opposing electron beam generator, so it is better to irradiate slightly forward or backward.

The present invention can also be achieved using three or more electron beam generators. It has also been proposed to install two generations of electron beam welding machines on the same welding line and perform welding for the purpose of preventing porosity and improving efficiency. As an application of this, it is also possible to weld by installing one and two or two electron beam generators at opposing positions across the web.

This method is also effective for butt welding of extremely thick plates, such as those with a thickness of 80 mm. Such extremely thick plates are manufactured by taking into account the tacking force of the electron beam and the prevention of pore defects.
Welding may be performed by irradiating electron beams from both sides. At this time, when the electron beam welding from one side is solidified and welding is performed on the opposite side, the spike defects from the previous weld are repaired by the subsequent welding, but the spike defects from the subsequent weld remain.

Therefore, it is necessary to take measures such as expanding the beam vibration width as described above. On the other hand, if welding is performed by irradiating electron beams from both sides simultaneously, the welding tip can be easily enlarged, and spike defects can be prevented without damaging the surface bead shape.

Examples Example 1 As shown in Fig. 1, a web 2 with a plate thickness of 50 mm is butted against a flange 1 with a plate thickness of 15 mm, and this is installed horizontally. The web was irradiated from both sides in a 5 degree direction. The distance from the polarizing lens 4 to the object to be welded was 500 mm in both cases. The electron beam irradiation conditions were the same for both: acceleration voltage +00kV, current 150mA, beam vibration 1kHz.
z, amplitude ±1 mm (at the surface position of the object to be welded), electron beam focus is approximately on the surface of the object to be welded, welding speed is 35 cm/m
It was done in. As a result, the bead appearance was good, and there were no fusion defects or pores, and good welding was achieved.

Example 2 The embodiment was the same as Example 1, except that the electron beam irradiation conditions were changed. One irradiation condition is an acceleration voltage of 100 kV, a current of 100 mA, an irradiation angle of 4 degrees downward, and a welding direction of progress of 6 degrees, and the other is an acceleration voltage of 100 kV, a current of 150 mA, an irradiation angle of 4 degrees downward, and a direction of welding of 5 degrees, By changing the angle of the welding progress direction, welding was carried out in such a way that the shallower weld penetration preceded the welding by 1Qmm. Also, the welding speed is 30
cm/min, and other conditions were the same as in Example 1.

As a result, the bead appearance was good, and no defects such as pores or poor fusion were observed.

Comparative Example This example is a comparative example, in which a joint under the same conditions as Example 1 was welded. However, one side of the electron beam irradiation during welding is
It was carried out in a state where the molten steel metal pools were not intersected by electron beam irradiation from both sides.

As a result, the appearance of the bead was good, but small pores, so-called spike defects, were observed at the tip of the welded bead that was later welded.

Effects of the Invention According to the present invention, electron beam welding of T-wall joints is easy and high quality can be obtained. In particular, if this method is used to manufacture T-shaped or H-shaped members for large steel structures, the effect of improving quality and reducing structural costs will be very large.
It has a great effect on industry.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of electron beam welding of a T-wall joint. Figure 2 is an explanatory diagram showing the problems of welding a T-shaped joint, Figure 3 is an explanatory diagram of welding a T-shaped joint using a plate with a convex part, and Figure 4 is an explanatory diagram showing the problems of welding a T-shaped joint.
The figure is an explanatory diagram of welding from the back side of the flange with a T-wall joint, No. 5
The figure is an explanatory diagram showing spike defects and poor fusion defects that occur during T-joint welding. 1-φ flange, 2--web 3 II @ψ electron beam irradiation, 4-book/acoustic deflection lens, 5... flange with convex portion, 6-φ spike defect, 7-fist fusion failure . Representative Patent Attorney Masaru Inoue

Claims (1)

[Claims] In welding a T-shaped joint by electron beam welding, an electron beam is irradiated from both sides of the web at the same time, and the molten metal pools formed by each electron beam irradiation are integrated. How to weld joints.