JP4357788B2 - Butt butt welding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for butt welding a closed container whose inside is substantially closed, and particularly to a butt welding method suitable for manufacturing a closed container made of an aluminum-based material.
[0002]
[Prior art]
In general, when butt-welding a structure, in order to prevent displacement due to thermal deformation, a plurality of butt portions of the joining elements constituting the structure are preliminarily welded in advance, and then the entire butt portion is fully welded. Like to do. In this case, if the thermal deformation has occurred due to the tack welding itself, it does not make a natural meaning. Therefore, the tack welding is performed under the condition that the minimum welding strength can be obtained with a small heat input. Like to do. However, when tack welding is performed under such conditions, the extra depth of the deposited metal increases as the penetration becomes shallower, especially when the structure is made of an aluminum-based material, depending on the thermal conductivity. The surplus appears excessively.
[0003]
FIG. 6 shows the state of the joint part after performing tack welding (arc welding) on the butt part C of the joining elements A and B constituting the structure made of the aluminum-based material. While the penetration depth d1 of the metal D is shallow, the surplus height d2 appears excessively, and the plate thickness is substantially increased at this tacking portion. Therefore, after that, when the entire butt portion C including the tacking portion is fully welded, as shown in FIG. 7, the phenomenon that the weld bead E does not reach the back surface side in the tacking portion, that is, the phenomenon that the back wave is not formed. Occurred and the unwelded portion F remains, making it difficult to ensure the desired welding quality. Therefore, conventionally, tack welding has been performed on the side opposite to the main welding side, and consideration has been given so as not to be affected by the surplus generated by tack welding.
[0004]
[Problems to be solved by the invention]
However, if the structure is a closed container, such as a pressure vessel, whose interior is substantially closed, a welding torch cannot be placed inside, so that it is temporarily attached on the surface side (the same side as the main welding). There was a problem that welding was unavoidable and it was extremely difficult to eliminate the lack of penetration in the above-described tacking portion.
In addition, by increasing the welding heat input of the main welding, the lack of penetration can be resolved, but in the case of an aluminum-based material, there is a restriction that melting is likely to occur due to a low melting point, The countermeasures had to be given up.
[0005]
The present invention has been made in view of the above-described conventional problems, and the problem is that even if tack welding is performed on the same side as the main welding side, the surplus can be kept sufficiently low. Accordingly, it is an object of the present invention to provide a closed container butt welding method that can provide a sufficient back wave even in the main welding and contribute to improvement in welding quality.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention includes a tacking portion after performing tack welding that obtains a minimum required welding strength at a butt portion of a joining element constituting a closed container made of an aluminum-based material. In the butt welding method for a closed container in which the entire butt portion is main-welded from the surface side, a concave hole that does not penetrate to the back side surface is formed on the surface side of the butt portion of the joining element, and the thickness of the bottom portion of the concave hole is It is formed so as to be smaller than the penetration depth obtained by the tack welding, and by arc welding, tack welding is performed while reaching the back side in the concave hole, and then the tacking portion. This is characterized in that the entire abutting portion including the main welding is performed so that a back wave is formed.
In the butt welding method of the closed container performed in this way, since the tack welding is performed in the recessed hole formed on the surface side of the butt portion, the occurrence of surging is suppressed, and as a result, the plate thickness of the tacking portion is also increased. Therefore, there will be no lack of penetration during the main welding. Further, since the thickness of the bottom portion of the concave hole is formed so as to be smaller than the penetration depth obtained by tack welding, the penetration in tack welding also reaches the back surface side, and a back wave is reliably obtained. It becomes like this.
[0007]
In the present invention, it is desirable to set the width of the concave hole smaller than the bead width by the main welding, so that no trace of the concave hole remains on the surface.
In the present invention, the shape of the concave hole is not questioned, but since the weld metal is formed in a conical shape in cross section, it is desirable to follow the conical shape (conical shape, pyramid shape). Also, the method of forming the concave hole is arbitrary. For example, it may be formed by counterbore processing in a state where the joint elements of the closed container are butted together, or in advance at the edge of the butted end surface of each joint element. A notch for synthesizing the recessed hole in the state of butting may be formed by embossing.
In the present invention, the type of the closed container to be joined is a pressure container made of an aluminum-based material, and in this case, the welding quality is sufficiently guaranteed, so that the application range as a pressure container is expanded.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0009]
FIG. 1 shows an aluminum alloy pressure vessel manufactured by a butt welding method according to the present invention. A pressure vessel 1 is connected to a cylindrical shell (joining element) 2 and both ends of the cylindrical shell 2. It consists of hemispherical shells (joining elements) 3, 4 butt welded by the method of the invention. This type of pressure vessel 1 is a closed vessel as a whole, although it is provided with an inlet / outlet 5 in one hemispherical shell 3, and is therefore at least retrofitted to the cylindrical shell 2. As described above, the tack welding 6 or 7 with the hemispherical shell 3 or 4 cannot be tack-welded from the inside, and is tack-welded from the outside in the same manner as the main welding.
[0010]
In the present embodiment, of the two hemispherical shells 3 and 4, the hemispherical shell 3 on the side where the supply / discharge port 5 is provided is retrofitted to the cylindrical shell 2, and therefore Here, the tack welding to the butted portion 6 of the hemispherical shell 3 and the cylindrical shell 2 to be attached later is applied from the outside in the same manner as the main welding.
For this reason, in the present embodiment, as shown in FIG. 2, the conical concave hole 10 is previously formed on the surface side of the abutting portion 6 between the cylindrical shell 2 and the hemispherical shell 3 attached to the cylindrical shell 2. Form. The concave hole 10 is formed by applying a counterbore to the butted portion 6 of the cylindrical shell 2 and the hemispherical shell 3 in this state, and is equally distributed in the circumferential direction. A plurality (three to four as an example) are formed.
[0011]
As shown in FIG. 2, the concave hole 10 is obtained by reducing the penetration depth d1 (FIG. 6) obtained by normal tack welding from the plate thickness (here, 4 to 5 mm) t of the shells 2 and 3. The depth h is set (h ≧ t−d1) so as to be equal to or slightly larger than the above value. In other words, the substantial plate thickness t1 at the bottom of the recessed hole 10 is smaller than the penetration depth d1 obtained by normal tack welding (t1 <d1). The maximum diameter (width) w of the recessed hole 10 is set so as to be smaller than the width W (FIG. 4) of the weld bead 15 by main welding described later.
[0012]
In manufacturing the pressure vessel 1, first, the other end of the cylindrical shell 2 and the other hemispherical shell 4 are butted together, and the butted portions 7 of both are welded. In this case, since one end of the cylindrical shell 2 is open, a plurality of locations (3 to 4 locations) of both the butting portions 7 are tack welded (arc welding) from the inside, and then the butting from the surface side. Arc welding (MIG or the like) is performed on the entire circumference of the portion 7. Therefore, in this welding, the penetration reaches the back surface side of the butting portion 7 sufficiently, so-called back waves are reliably formed, and the welding quality is also sufficient.
[0013]
When the joining of the other hemispherical shell 4 to the cylindrical shell 2 is completed, the cylindrical shell 2 and one hemispherical shell 3 are then butt welded. In this butt welding, first, the cylindrical shell 2 and the hemispherical shell 3 are butted together, both the butt portions 6 are subjected to counterbored holes, and the concave holes 10 are formed at necessary positions in the circumferential direction. Subsequently, tack welding (arc welding) is performed in the recessed hole 10. Then, since the thickness t1 (FIG. 2) of the bottom of the concave hole 10 is smaller than the penetration depth d1 (FIG. 6) obtained by normal tack welding, as shown in FIG. The penetration of the base material reaches the back surface side, so that the weld metal 12 is formed almost without rising from the general surfaces of both shells 2 and 3. That is, almost no surplus is formed. Therefore, when the entire circumference of the butt portion 6 between the cylindrical shell 2 and the hemispherical shell 3 is thereafter arc welded (MIG or the like), as shown in FIG. Also in the welded portion, the penetration reaches the back surface side, so that a so-called back wave is reliably formed, and as a result, the welding quality is sufficient. Further, as shown in FIG. 4, the weld bead 11 by this main welding is sufficiently raised from the general surfaces of the shells 2 and 3, so that the concave hole 10 is completely covered by the weld bead 11 and the surface thereof is covered. The trace (undercut) of the concave hole 10 does not remain, and the anxiety on the strength surface and the design surface is eliminated.
[0014]
Here, in the above-described embodiment, the concave hole 10 is formed by counterboring, but the method of forming the concave hole 10 is arbitrary, for example, as shown in FIG. You may make it form the square notch 13 which synthesize | combines a concave hole in the state which mutually faced in the edge part of each butt | matching end surface of the shell 2 and the hemispherical shell 3 by stamping. In this case, when the cylindrical shell 2 and the hemispherical shell 3 are abutted with each other, a pyramid-shaped concave hole is formed in the abutting portion 6 of the both, so that the concave hole 10 is formed by the counterbored hole processing. As described above, the troublesome work of counterbore machining after the cylindrical shell 2 and the hemispherical shell 3 are assembled together becomes unnecessary.
[0015]
Of course, the shape of the concave hole 10 formed in the abutting portion 6 of the cylindrical shell 2 and the hemispherical shell 3 may be a simple circular hole or a square hole instead of the above-described weight shape. is there.
Moreover, the kind of welding performed by this invention is arbitrary, TIG, laser welding, etc. are employable besides above-mentioned MIG.
Furthermore, the application object of the present invention is arbitrary, and can be applied to welding of various closed containers whose insides are substantially closed in addition to the pressure container 1 made of the above-mentioned aluminum-based material. Is applicable to various materials other than the above-described aluminum-based materials.
[0016]
【The invention's effect】
As described above, according to the butt welding method for a closed container according to the present invention, even if tack welding is performed on the same side as the main welding side, the surplus can be suppressed sufficiently low. Even in the part, sufficient penetration to form a back wave can be obtained, and good welding quality can be ensured, especially suitable for the production of closed containers made of materials with good thermal conductivity such as aluminum. It becomes.
[Brief description of the drawings]
FIG. 1 is a schematic view showing the structure of a pressure vessel made of an aluminum-based material manufactured by a butt welding method according to the present invention.
FIG. 2 is a cross-sectional view showing a shape of a concave hole formed in a butt portion when the butt welding method is performed.
FIG. 3 is a cross-sectional view showing a state of a joint portion after tack welding by the butt welding method.
FIG. 4 is a cross-sectional view showing a state of a joint portion after the main welding by the main butt welding method.
FIG. 5 is a perspective view showing another embodiment of forming a concave hole employed in the butt welding method.
FIG. 6 is a cross-sectional view showing a state of a joint after tack welding by a conventional butt welding method.
FIG. 7 is a cross-sectional view showing a state of a joint after main welding by a conventional butt welding method.
[Explanation of symbols]
1 Pressure vessel (closed vessel)
2 Cylindrical shell (joint element)
3 Hemispherical shell (joint element)
6 Butt 10 Recessed hole 11 Weld bead 12 Weld metal 13 for tack welding Notch for forming recessed hole

Claims (4)

After tack welding that provides the required minimum welding strength to the butt portion of the joining element that constitutes the closed container made of an aluminum-based material, the entire butt portion including the tack portion is subjected to main welding from the surface side. In the butt welding method of the closed container , a concave hole that does not penetrate to the back side surface is formed on the surface side of the butt portion of the joining element, and the thickness of the bottom portion of the concave hole is determined by the penetration depth obtained by the tack welding. Are formed so as to be smaller, and by arc welding, tack welding is performed while reaching the back surface side in the concave hole, and then the entire butt portion including the tacking portion is back-waved. A method of butt welding a closed container, characterized in that the main welding is performed so as to be formed.   2. The method of butt welding a closed container according to claim 1, wherein the width of the concave hole is set smaller than the bead width by the main welding.   The method of butt welding a closed container according to claim 1 or 2, wherein the concave hole has a weight shape.   The method of butt welding a closed container according to any one of claims 1 to 3, wherein the closed container is a pressure container.

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