JPH09271992A - Backing material for t-joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backing material for T-joint which can prevent the development of a notching at the time of welding the T-joint and can execute the sound welding while avoiding the lowering of efficiency, such as the welding to both surfaces, and has wide applicable allowance at the time Of applying the actual welding. SOLUTION: The backing material 23 for the T-joint is composed of a solid refractory used to form the T-joint by butting a horizontal material 22 on the side surface of a vertical material 21. This backing material 23 is arranged at the butting corner part of the horizontal material 22 and the vertical material 21 and comparted with a first part 24 contacting with the lower surface of the horizontal material 22 toward the vertical material from the further side from the vertical material 21 at the upper surface, a second part 25 separated in a suitable length interval from the lower surface of the horizontal material and paralleled with the lower surface of the horizontal material and a third part 26 descending toward the vertical material. This third part 26 is sloped flat surface but can be formed as curved surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas shield arc welding method for a T-shaped butt joint having a rectangular groove of a steel structure such as a joint (joint) between a column and a beam in a building steel frame. The present invention relates to a backing material for a T-joint used for a downward or lateral single-sided welded joint.

[0002]

2. Description of the Related Art Conventionally, a backing metal has been generally used for welding a joint portion of a building steel frame or the like. By using this backing metal, there is an advantage that welding can be always performed with a high current and the welding efficiency can be increased. However, since this backing metal is not removed even after welding, an unmelted portion remains between the member to be welded (base material). That is, as shown in FIG.
A horizontal member 2 whose tip is a square groove is butt-joined to a vertical member 1 in a T-shape, and a backing plate 3 is applied below the butted portion. Then, the weld metal 4 is formed by welding the concave groove portion. In this case, the backing metal 3 is also partially melted in the groove portion, and the vertical member 1, the horizontal member 2, and the backing metal 3 are once melted in this portion and then solidified and integrated. But,
An unmelted portion 5 remains between the lower portion of the backing plate 3 and the side surface of the vertical member 1, which functions as a notch when stress concentration occurs and serves as a starting point for cracking. Further, an unmelted portion 6 is also formed between the horizontal member 2 and the backing plate 3.

As described above, when the unmelted portions 5 and 6 are present, the unmelted portions 5 and 6 function as notches and serve as a starting point of cracks when stress concentration or the like occurs. Therefore, in terms of earthquake resistance. There's a problem.

In order to prevent the generation of such unmelted portion, as shown in FIG. 7, after the backing metal is removed by gouging or the like, the back surface is welded again to form the back surface weld metal 7. Alternatively, as shown in FIG. 8, it is necessary to form the weld metals 8 and 9 by performing double-sided welding from the front and back with a groove shape of K shape.

However, as described above, if the back surface is welded after gouging or after welding the front surface side with a K-shaped groove, there is a problem that defects are likely to occur during this back surface welding. Further, when welding is performed at a construction site, the back surface is upwardly welded, so that there is a drawback that the efficiency is extremely poor, which is not practical.

On the other hand, as a method of solving the problems in double-sided welding using a backing metal, application of the single-sided welding method generally used in shipbuilding and ships is considered. However, single-sided welding in ships and vessels is for welding plates to each other with a flat joint, and the T-joint is generally constructed by fillet welding. Therefore, the one-sided welding method for the T-joint is not actually practiced. FIG. 9 is a diagram showing this one-sided welding method. The materials 10 and 11 to be welded having a groove shape are horizontally butted so that a V groove is formed between them, a backing material 12 is arranged below the groove and welded, and a weld metal 13 is formed. To form. Thus, single-sided welding is usually a welding method for flat joints, and single-sided welding for T-joints is not suitable.

Therefore, Japanese Utility Model Publication No. 2-16874 proposes a one-sided welding backing material for a T-joint, which is an improved backing material and enables one-sided welding of a T-joint.
10 and 11 show a conventional backing material for one-sided welding of a T-joint. A backing material 14 is arranged on the lower surface of the abutting portion of the vertical material 1 and the horizontal material 2. This backing material 14
Is provided with a recessed portion 17 at a backing portion corresponding to the root interval, and the recessed portion 17 is a circular arc surface, and end faces of both ends of the circular arc surface are orthogonal to the corresponding welded portions. The backing material 14 is made of a material that does not melt with the welding material.

[0008]

However, in the backing material for single-sided welding disclosed in Japanese Utility Model Publication No. 15874/1990, as shown in FIG. 10, the shape of the recessed portion 17 is adjusted to a wide groove gap. Designing makes welding difficult when the groove is narrow. That is, when the groove gap is narrow, the weld metal 15 obtained is small and sufficient penetration cannot be obtained, so that the fusion failure 16 occurs. Further, since the gap 16 ′ between the horizontal member 2 and the backing member 14 is large, an overlap occurs when the weld metal enters.

On the other hand, as shown in FIG. 11, when the shape of the concave portion 17 is determined according to the narrow gap, the backing material 14
Since the slag cannot be stored in the upper surface portion 18, the undercut occurs. If the arc directly hits the backing material, the backing material will be fused with the weld metal. As described above, the conventional backing material for single-sided welding has a drawback in that it has low adaptability to changes in the root distance due to the taper gap or the like.

The present invention has been made in view of the above problems, and it is possible to prevent the occurrence of a notch during welding of a T-joint, and to avoid a decrease in efficiency as in double-sided welding, while maintaining a sound quality. An object of the present invention is to provide a backing material for a T-joint which can be welded and has a wide application margin that can be used in actual welding application.

[0011]

A backing material for a T-joint according to the present invention is for a T-joint made of a solid refractory used for forming a T-joint by abutting a horizontal member on a side surface of a vertical member. In the backing material, the first part is arranged at the abutting corner of the horizontal material and the vertical material, and the upper surface thereof contacts the lower surface of the horizontal material from the side farthest from the vertical material toward the vertical material. And spaced from the lower surface of the horizontal member at an appropriate length,
It is characterized in that it is divided into a second portion parallel to the lower surface of the horizontal member and a third portion descending toward the vertical member.

In this T-joint backing material, for example,
The third part is an inclined flat surface or the third part is a curved surface. The interval between the second part and the horizontal member is 0.5 to 2.5 mm, and the boundary between the second part and the first part,
The distance from the tip of the backing material is preferably 12 mm or more. The depth of the backing material tip of the third part is 3 to 10 mm, and the distance between the boundary between the second part and the third part and the backing material tip is 3 to 10 m.
m is preferable.

In the present invention, the upper surface of the backing material is divided into the first part to the third part, and in particular, the first part which contacts the lower surface of the horizontal member and the third part which is located under the groove. There is a second portion spaced apart from the horizontal member by an appropriate length. At the time of welding, since the molten slag is stored in the second portion, the slag is prevented from biting into the material to be welded (vertical material and horizontal material), and the occurrence of undercut is suppressed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
This will be specifically described with reference to the accompanying drawings. FIG. 1 is a diagram showing a backing material 23 according to an embodiment of the present invention. Vertical material 2
1, the end faces of the horizontal member 22 subjected to the oblique groove processing are butted against each other, and both are arranged in a T shape. Then, on the lower surface of the horizontal member 22, a backing member 23 made of the solid refractory material of this embodiment is arranged. The backing material 23 has a first portion 24, a second
It is divided into a part 25 and a third part 26. The first portion 24 is in contact with the lower surface of the horizontal member, and the third portion 26 is formed so as to descend toward the vertical member 21 at the lower part of the groove between the horizontal member 22 and the vertical member 21. . In this embodiment, the third part is an inclined plane.

The second portion 25 is formed by cutting out in a stepwise manner from the surface of the first portion 24 at a constant depth.
It is separated from the horizontal member 22 by an appropriate length and is parallel to the horizontal member 22.

In the backing material thus constructed, when the groove portions of the horizontal member 22 and the vertical member 21 are welded,
The molten slag enters the gap between the horizontal member 22 and the backing member 23 in the second portion 25 and the slag is stored, so that the vertical slug 21 and the horizontal member 22 are prevented from digging into the slag and defects such as undercuts occur. Can be prevented.

Further, in the third portion 26, the horizontal member 22
The molten metal is stored in the gap formed between the backing material 23 and the backing material 23, and at the same time, the backing material itself is melted,
A back bead is formed.

In this embodiment, as shown in FIG. 2, the second portion 25 is formed with a step with respect to the first portion 24.
The third portion 26 is inclined in a plane. However, the present embodiment is not limited to this, and as shown in FIG.
The portion 26 may be curved with a curved surface.

On the other hand, as shown in FIG. 4, in the embodiment shown in FIGS. 1 and 2, the depth (distance between the horizontal member and the backing member) of the second portion 25 is a and the width of the second portion 25 ( The distance from the boundary between the first part 24 and the second part 25 to the tip of the backing material) is b, the third
The width of the portion (the distance from the boundary between the second portion 25 and the third portion 26 to the tip of the backing material) is d, and the depth at the tip of the backing material of the third portion is c.

In this case, the depth of the second portion 25 (second portion 2
5 and the horizontal member 22) a is 0.5 to 2.5 mm
It is preferred that If the distance a is less than 0.5 mm, it is smaller than the thickness of the slag, and thus it is not possible to prevent the occurrence of undercut due to the biting of the slag. On the other hand, if the distance exceeds 2.5 mm, not only the molten slag but also the molten metal may enter the second portion, and defects such as overlap may occur.

When the width b of the second portion 25 is less than 12 mm, the slag cannot be stored sufficiently when the route interval is large within the practical range. Therefore, the width b of the second part
Is preferably 12 mm or more.

The width d of the third portion 26 is preferably 3 to 10 mm, and the depth c thereof is preferably 3 to 10 mm. The difference between the depth c and the width d is within 2 mm.

If the depth c and the width d are less than 3 mm, a back bead having a sufficient leg length cannot be obtained. Further, when the route interval is small, the heat quantity of the molten metal is insufficient, so that a bead sufficiently melted in the member to be welded cannot be obtained, and defects such as defective fusion occur. On the contrary, when the depth c and the width d exceed 10 mm, the bead cross-sectional shape (bead height / bead width) becomes large and the high temperature crack is likely to occur when the root interval is small. Further, since the arc does not reach the member in which the member to be welded and the backing material are in contact with each other, it does not sufficiently melt into the standing plate side and defects such as defective fusion occur.

Regarding the bead width and the depth, when the depth is deeper than the width of the groove, the value of the bead cross-sectional shape becomes large and the possibility of hot cracking increases, and the welded object The arc hardly reaches the member where the member and the backing material are in contact with each other, and defects such as fusion failure are likely to occur. In addition, when the width increases with respect to the depth, the cross-sectional shape of the bead does not become smooth, and the bead becomes a convex bead.

On the other hand, in the case of the embodiment shown in FIG.
As shown in FIG. 4, when the third portion 26 is a quarter circular arc, the radius c is preferably 3 to 10 mm, and therefore the portions corresponding to c and d in FIG. 4 are also in the range of 3 to 10 mm. Radius c
Is less than 3 mm, a back bead with a sufficient leg length cannot be obtained, and when the route interval is small, the amount of heat of the molten metal is insufficient, so a bead that has sufficiently melted in the welded member cannot be obtained, and overlap beads, etc. Defects occur.

On the contrary, when the radius of curvature c exceeds 10 mm,
If the route interval is small, the value of the bead cross-sectional shape (bead height / bead width) becomes large, and hot cracking is likely to occur. Further, since the arc does not reach the portion where the member to be welded and the backing material are in contact with each other, it does not sufficiently melt into the standing plate side and defects such as overlap occur. Therefore, the radius of curvature of the curved surface of the third portion 26 is preferably 3 to 10 mm.

[0027]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Tables 1 to 4 below show the shapes of the backing materials and the quality of their welds in Examples and Comparative Examples of the present invention.

Examples 1 to 3, 8 to 10 and Comparative Example 4
7 to 11 are cases of the backing material for T-joint (third part plane) shown in FIGS. 1 and 2, and Examples 12 to 14 and Comparative Examples 15 to 18 are backings for T-joint shown in FIG. This is for the case of the patch (third curved surface: 1/4 arc).

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

However, the welding conditions were such that a solid wire (JIS Z3312YGW11) having a diameter of 1.4 mm was used and downward welding was performed by semi-automatic welding at 250A-28V. In addition, in poor fusion, overlap, undercut, and high temperature crack, ◯ means no defect, and × means harmful defect. In the convex bead column, ∘ indicates that the bead shape is good, and Δ indicates that the bead shape is convex, although the bead shape does not cause a structural problem.

In each of these tables, the route interval is shown in FIG.
As shown in FIG. Further, FIG. 13 shows the case where a good bead shape is obtained. FIG. 14 shows a convex bead shape. FIG. 15 shows a state of fusion failure on the member A (vertical member) side. FIG. 16 shows the state of overlap on the member B (horizontal member) side. FIG. 17 shows an undercut state on the member B side. FIG. 18 shows a state of hot cracking.

As is clear from these Tables 1 to 4,
In all of the examples of the present invention, the weld quality was excellent. On the other hand, in Comparative Examples outside the scope of the present invention, any of convex bead, fusion failure, overlap, undercut or hot cracking occurred, and the weld quality was poor.

[0036]

As described above, according to the present invention,
A second part is provided on the surface of the backing material in parallel with the horizontal material at an appropriate length so that convex beads, fusion defects, overlaps, undercuts and hot cracks are prevented, and excellent weld quality is obtained. You can

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the shape of the backing material of the same.

FIG. 3 is a diagram showing a backing material of a second embodiment of the present invention.

FIG. 4 is a diagram illustrating the dimensions of the first embodiment.

FIG. 5 is a diagram for explaining the dimensions of the second embodiment.

FIG. 6 is a view showing a notch generated in a conventional backing material.

FIG. 7 is a view showing a welding state after conventional gouging.

FIG. 8 is a diagram showing a state of conventional double-sided welding.

FIG. 9 is a view showing the shape of a conventional flat joint.

FIG. 10 is a diagram showing a state of a conventional unmelted portion.

FIG. 11 is a diagram showing fusion bonding of a conventional backing material.

FIG. 12 is a diagram showing route intervals.

FIG. 13 is a view showing a good bead shape.

FIG. 14 is a view showing a convex bead.

FIG. 15 is a diagram showing defective fusion.

FIG. 16 is a diagram showing overlap.

FIG. 17 is a diagram showing undercut.

FIG. 18 is a diagram showing hot cracking.

[Explanation of symbols]

 21: Vertical material 22: Horizontal material 23: Backing material 24: Part 1 25: Part 2 26: Part 3

Claims (5)

[Claims] 1. A horizontal member is abutted against the side surface of a vertical member and T
In a backing material for a T-joint made of a solid refractory used for forming a shaped joint, the T-joint backing material is arranged at a butt corner between the horizontal member and the vertical member, and its upper surface is from the side farthest from the vertical member. To the vertical member, a first portion that contacts the lower surface of the horizontal member, a second portion that is separated from the lower surface of the horizontal member at an appropriate length and is parallel to the lower surface of the horizontal member, and the vertical member A backing material for a T-joint, characterized in that the backing material is divided into a third part that descends. 2. The backing material for a T-joint according to claim 1, wherein the third portion is an inclined flat surface. 3. The backing material for a T-joint according to claim 1, wherein the third portion is a curved surface. 4. The distance between the second portion and the horizontal member is
It is 0.5 to 2.5 mm, and the distance between the boundary between the second portion and the first portion and the tip of the backing material is 12 mm or more, any one of claims 1 to 3. The backing material for a T-joint according to item 1. 5. The depth of the tip of the backing material of the third part is 3 to 10 mm, and the distance between the boundary between the second part and the third part and the tip of the backing material is 3 mm. The backing material for a T-joint according to any one of claims 1 to 3, wherein the backing material has a thickness of 10 to 10 mm.