JPH0761539B2 - Enclosed arc welding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an enclosed arc welding method for performing enclosed welding with a rod-shaped material to be welded such as a reinforcing bar standing vertically.

[Prior Art] The conventional enclosed arc welding method in the case of a vertical joint was performed by processing a so-called oblique I-shaped groove (Japanese Patent Publication No. 52-
No. 35624). FIG. 4 is a side view showing a conventional closed arc welding method in the case of a vertical joint, and FIG.
It is sectional drawing by a line. In this method, for example,
A deformed rebar 1 is provided with its joint surface inclined with respect to its axial direction, and two rebars 1 are arranged one above the other with a predetermined groove space provided between them to form a pair of split coppers. The dowel 2 is arranged so as to surround the groove space. Then, the welding rod 3 is inserted into the groove space from the welding port 4 of the copper plate 2 provided on the upper side of the groove space, and the weld metal is filled from the lower part of the groove space to the upper part thereof. As a result, the materials to be welded in the fixed vertical posture can be joined quickly and soundly.

Thus, in recent years, as a method of joining reinforcing bars embedded in concrete columns of reinforced concrete buildings, it has been possible to attach them by the pre-assembly method in order to improve the efficiency of the method of joining one by one at the construction site. It's getting more and more. In other words, in the factory or on the ground, two or more reinforcing bars are two-dimensionally arranged in the cross-sectional area of the pillar, which are stacked at the construction site, and the stacked assemblies are welded in a vertical posture. The Iku-Amae method is used for large-scale reinforced concrete buildings.

The above-mentioned enclosed arc welding method has the advantage that the workability of the hoop streak, which is a post-process, is good without excessively enlarging the shape of the joint joint part. It is used.

[Problems to be Solved by the Invention] However, the conventional enclosed arc welding method is
Since the weld groove has an oblique I shape, it has the following drawbacks. That is, in the case of this oblique I-shaped groove, there is a constraint that welding must be performed by inserting a welding rod into the groove from above in the extension direction of the groove surface. For this reason, in the pre-assembled rebar construction method, it is necessary to pre-assemble the rebar so that the groove will be in that direction in consideration of the direction of welding work in advance. In consideration of the welding process direction, it is necessary to process the inclined joint surfaces so that they are parallel to each other.

For this reason, it is necessary to strictly control the direction of the reinforcing bars during pre-assembly, and despite the fact that the pre-assembly method is adopted for the purpose of speeding up and improving efficiency, the work is actually extremely complicated and inefficient. There is a problem that it is target.

In addition, inclining the joining surface of the reinforcing bar with respect to the axis, the process is complicated and the amount of cutting is increased,
There is a problem that the yield decreases. Furthermore, when this groove processing is performed by gas cutting on site, gas notches are likely to occur, and there is a disadvantage that much labor is consumed in the grinder grinding work of the groove surface (bonding surface).

The present invention has been made in view of such problems,
It is an object of the present invention to provide an enclosed arc welding method in which the joining surface of the groove can be easily processed, the groove processing time can be shortened, and there is no restriction on the front assembly, which enables quick and easy front assembly. To aim.

[Means for Solving the Problems] The enclosed arc welding method according to the present invention has a pair of materials to be welded, each of which has a rod shape and whose joint surface is substantially perpendicular to its axial direction. A predetermined groove space is provided and arranged vertically, and a predetermined gap is provided between the material that surrounds a part of the groove space by contacting the side surface of the lower material to be welded and the upper material to be welded. First, molten metal is piled up from the lower side of the material to be welded in the vicinity of the material to form a bridging portion.

Incidentally, the joint surface is substantially perpendicular to the axial direction of the rod-shaped material to be welded, when performing welding by the method of the present invention,
It means that there is no inclination that limits the mounting position of this material and the insertion position of the molten material, etc.In other words, there is no problem in terms of inclination without considering the directionality of welding in construction. included.

Further, forming molten metal from the side of the material to be welded below to form the bridging portion means that the bridging portion is entirely or more than a half portion thereof bulged from below, and the bridging portion is formed. In the process, molten metal may be slightly deposited on the upper side of the material to be welded, or molten metal may be deposited for confirmation of arc generation or the like.

Furthermore, when this material is stacked on the side surface of the material to be welded below, it is not necessary to contact this material with the material to be welded on the entire surface of the overlapped area, but there is contact with a part of that area. Just do it. Further, it is needless to say that this material does not need to contact the entire side surface of the material to be welded below.

[Operation] In the present invention, a horizontal groove is provided, and the material is placed in contact with the side surface of the lower member to be welded. This material surrounds a part of the groove space and is arranged with a predetermined gap between it and the material to be welded above.

Then, in the vicinity of the material, the weld metal is piled up from the lower side of the material to be welded to form a bridging portion. In this case, since the material is disposed on the far side of the groove, the end of the joint surface of the materials to be welded does not burn through at the start of welding. Further, by using this material, a bridging portion can be easily provided between the joint surfaces of the upper and lower materials to be welded. Furthermore, since the slag floats upward and is discharged from the gap formed between this material and the material to be welded above, the slag does not remain in the welded portion between the joint surfaces.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 (a) to 1 (e) are schematic diagrams showing an enclosed arc welding method according to an embodiment of the present invention in process order,
FIG. 2 is a sectional view taken along line II-II of FIG.

The upper reinforcing bar 11 and the lower reinforcing bar 12 have their joint surfaces substantially perpendicular to the axial direction. Therefore, when the reinforcing bars 11 and 12 are arranged vertically with their axial directions aligned, both joint surfaces are Are substantially horizontal and parallel to each other. The copper metal plate 14 has a U-shaped horizontal cross section, and is arranged so as to hold the reinforcing bars 11 and 12 around a groove space 15 formed between the upper reinforcing bar 11 and the lower reinforcing bar 12. Both of the reinforcing bars 11 and 12 are held by a pair of clampers (not shown) fixed to a copper plate 14 so that their opposite ends have the same axis. It is arranged so as to face up and down via the 14 and the clamper.

Behind the groove space 15 between the reinforcing bars 11 and 12, there is a recess 16 in the copper plate 14
Is formed, and the material 13 is disposed in the recess 16 in contact with the side peripheral surface on the back side of the lower reinforcing bar 12. The strip 13 is fixed by being pressed against the lower rebar 12 from behind by a bolt 17 that horizontally penetrates the copper strip 14.

After arranging the upper rebar 11, the lower rebar 12, the bar 13 and the copper plate 14 in this manner, as shown in FIG.
Insert 18 into the groove space 15 from the U-shaped open side of the copper dowel 14,
Welding is started from the vicinity of the material 13 (back side of the groove space 15). That is, first, the material 13 on the joint surface of the lower rebar 12 is
Start the arc at a position of 5 to 6 mm before, and immediately move the arc to the corner between the joint surface of the lower reinforcing bar 12 and the material 13 and perform semi-weaving while shortening the arc, and melt the molten metal. Wait for the excitement.

Then, as shown in FIG. 1 (b), the molten metal 20 is applied to the material.
Assemble on the joint surface of the lower rebar 12 using 13. In this case, the generated slag 21 floats on the molten metal 20. Then, the joining surface (upper groove) of the upper rebar 11 and the molten metal
When the distance from 20 becomes 2 to 3 mm, the semi-weaving is stopped, the arc is stopped and the corner of the upper groove is melted and bridged.

After the upper rebar 11 and the lower rebar 12 are bridged, as shown in Fig. 1 (c), the semi-weaving is performed and the generated slag is used in the gap between the upper rebar 11 and the bar 13. The welding rod 18 is alternately turned upward and downward while being discharged to the outside of the groove to secure the melting of the upper groove side and the lower groove side. In this way, as shown in FIGS. 1 (d) and 1 (e), the molten metal 20 is continuously laminated to the foremost part of the groove. Then
The arc is stopped, the molten metal 20 is cooled and solidified, and then the clamper is removed to complete the welding.

In the method of the present embodiment, a small piece of material
By bringing 13 into contact with the lower reinforcing bar 12 side, it is possible to bridge the weld metal 20 between the upper reinforcing bar 11 and the lower reinforcing bar 12. Then, the I-shaped groove formed at the joint surface between the upper reinforcing bar 11 and the lower reinforcing bar 12 is arc-welded vertically. When welding without using this material 13,
A proper bridging between the upper reinforcing bar 11 and the lower reinforcing bar 12 is not formed in the inner part of the I-shaped groove. Due to the welding position, molten metal 20
Is spread only on the groove surface (joint surface) of the lower rebar 12
Because it is difficult to reach 11. As described above, the small piece of material 13 has a function of depositing the molten metal 20 in the deep part of the groove and promoting bridging between the upper and lower reinforcing bars.

In order to obtain such an effect, the central angle θ formed by the both ends of the lower rebar 12 in the circumferential direction of the material 13 with the axial center of the rebar 12
Is required to be 30 ° or more. However, if this material is too large, it will be difficult to discharge the slag 21 during the enclosed arc welding out of the groove, and it is easy to cause welding defects such as large-scale slag entrainment and fusion failure resulting from this. Become. For this reason, the material 13 is stopped at a central angle θ so as to cover an area of about (150/360) ° or less of the outer circumference of the reinforcing bars 11 and 12 to be welded.

The distance d (mm) between the upper reinforcing bar 11 and the material 13 is 2 to D /
It is preferably 2 mm. However, D (mm) is the upper rebar 11
And the lower rebar 12 is the distance. When d is less than 2 mm, the escape of the slag 21 becomes poor and the slag is apt to be caught. Moreover, in order to discharge the slag 21, a high degree of skill and strict monitoring of welding conditions are required. On the other hand, d is
If it exceeds D / 2, it is difficult to form a bridging portion by the molten metal 20. Therefore, the joint is not completed.

Incidentally, in welding, the inner peripheral surface of the material 13 and the outer peripheral surface of the rebar 12 are curved with the same curvature, and the material 13 is in full contact with the rebar 12 within the range of the central angle θ described above. Is ideal. However, as shown in FIG. 3 (a), the case where the diameter of the lower reinforcing bar 12 is large and a gap a is formed between the central portion of the bar 13 and the reinforcing bar 12, and FIG. 3 (b). In some cases, the lower rebar 12 has a small diameter, and both ends of the bar 13 are separated from the peripheral surface of the rebar 12 by a distance b as shown in FIG. Also in this case, if a is about 2 mm or less and b is 2 to 3 mm, the same effect as contacting the lower reinforcing bar 12 on the entire surface of the material 13 can be obtained. As a result, a dedicated material for each rebar with different cross-sectional diameter
The complexity of preparing 13 can be avoided.

Next, the result of the vertical welding of the I-groove actually performed by the method of the embodiment of the present invention will be described.

Used reinforcing bar; SD35, SD40 (JIS) Reinforcing bar shape; JIS G3112 (steel bar for reinforced concrete) Reinforcing bar diameter: 22 mm for D21, 38 mm for D38; 38 mm welding rod; for SD35, use JIS D5816 For SD40, JIS D7016 Groove spacing; 10 mm and 14 mm for D22, 12 mm for D38
And 16mm This material is 25mm wide, 20mm long and 10mm thick SM41 material (JI
S) Welding current: 150 to 170 A in case of D38, 120 to 130 A in case of D22 The characteristics of the welded portion obtained by welding under these welding conditions are shown in Table 1 below.

Both have sufficient strength and ductility.

Further, Table 2 below shows the welding results of the case of using the D41 rebar having a diameter of 41 mm and the case of welding by the method of the present invention and the case of performing welding by the conventional method in comparison with each other.

As is clear from Table 2, according to the method of the present embodiment, the required time is approximately halved as compared with the conventional method, and the efficiency is extremely high.

Further, as described above, since the joining surface can be horizontal and the enclosed arc welding can be performed, when the rebar is pre-assembled,
It is not necessary to assemble the reinforcing bar in consideration of its directionality, and therefore, it is possible to quickly assemble the rebars, and the advantages of the preassembly method can be fully utilized. Further, since it is sufficient to form a joint surface substantially perpendicular to the axial direction of the reinforcing bar, it is easy to form a groove shape and the yield is high because there are few cut-off portions.

[Effect of the Invention] According to the present invention, there is an advantage that the groove shape is an I-shape that is perpendicular to the axial direction of the material to be welded, and there is no restriction on the directionality of the reinforcing bar axis to be constructed. Further, since the groove is perpendicular to the axis of the reinforcing bar, the groove can be used as it is obtained from the reinforcing bar, or can be used as it is for high speed cutting or gas cutting, and the processing is simple.

Furthermore, it is not necessary to remove slag until the end of welding, and the groove area is reduced to 70% of that of the conventional method, so welding can be performed with even higher efficiency.

Furthermore, it is not necessary to draw the rebars to be joined together, and it is possible to construct a joint for the restrained rebars.

As a result, according to the present invention, the work at the construction site can be made highly efficient, and welding can be performed at low cost.

[Brief description of drawings]

1 (a) to 1 (e) are schematic diagrams showing an enclosed arc welding method according to an embodiment of the present invention in the order of steps, and FIG. 2 is a sectional view taken along line II-II of FIG. 1 (a). Figure 3 (a),
(B) is a plane sectional view of a reinforcing bar, FIG. 4 is a side view showing a conventional method, and FIG. 5 is a sectional view taken along line VV of FIG. 11,12; Reinforcing bar, 13; Material, 14; Copper metal, 15; Groove space

Claims (3)

[Claims] 1. A pair of materials to be welded, each of which has a rod-like shape and whose joint surface is substantially perpendicular to its axial direction, is arranged vertically with a predetermined groove space provided between the joint surfaces. A material which is in contact with the side surface of the material to be welded and surrounds a part of the groove space is disposed with a predetermined gap between the material to be welded above, and first, in the vicinity of the material, a lower portion is provided. The method for enclosing arc welding, wherein a bridging portion is formed by pouring molten metal from the side of the material to be welded. 2. A gap between the material and the upper material to be welded is
It is 2 mm or more, and is 1/2 or less of the distance between the joint surfaces of the upper and lower welded materials.
The enclosed arc welding method described in. 3. The enclosure according to claim 1, wherein the material is in contact with an axis of the lower material to be welded in a region having a central angle of 30 to 150 °. Arc welding method.