JPH07108457B2 - 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 fixed vertical workpieces can be quickly and soundly joined.

In recent years, as a method of joining reinforcing bars embedded in concrete columns of reinforced concrete buildings, they must be assembled by the pre-assembly method in order to improve the efficiency of the method of joining one piece at a construction site. Is increasing. 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 is.

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. Arranged vertically with a predetermined groove space, the steel material whose strength is substantially the same as or less than the material to be welded is brought into contact with the side surface of the material to be welded below, and the groove space is provided. Place it so as to surround a part of
At this time, the distance between this material and the material to be welded above is 2 mm or more, and is 1/1 / the gap between the joint surfaces of the material to be welded above and below.
A gap of 2 or less is provided, and then arc welding is performed between the joint surfaces.

The fact that the joint surface is substantially perpendicular to the axial direction of the rod-shaped material to be welded means that it does not have an inclination to the extent that it restricts the attachment position of the material and the insertion position of the molten material. If so, the inclination is included so that there is no problem in construction without considering the direction of welding.

Further, arc welding is performed between the joining surfaces, and for example, molten metal is deposited from the lower side of the material to be welded to form a bridging portion. In this case, all or a portion of the bridging portion or more is lowered downward. It's good if you serve In the process of forming this bridge,
A slight amount of molten metal may be deposited on the upper side of the material to be welded, or a molten metal may be deposited to confirm the occurrence of an arc.

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, for example, welding is started from an arc-shaped corner formed by the material and the material to be welded below, and weld metal is laid from the side of the material to be welded below to form a bridging portion.

In this case, since the material is disposed on the far side of the groove, the end portion 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.

Furthermore, this material is made of a metal or alloy whose strength is substantially the same as or lower than that of the material to be welded. For example, when the material to be welded is a reinforcing bar, steel is used as the material. Therefore, when welding progresses between the joint surfaces, this material also melts in part and is joined to the welded portion, and the material itself becomes a part of the joint. As a result, the joint is reinforced with the material, and the operation of removing the material after welding is unnecessary, so that the work is simplified.

[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 Face horizontally and parallel. 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.

This material 13 is made of a reinforcing bar material whose strength is substantially the same as or lower than that of the reinforcing bars 11 and 12 as the materials to be welded. Therefore, when welding the reinforcing bar, for example, the same kind of material or structural steel as the reinforcing bar may be used.

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 and the arc is stopped to melt the corner portion of the upper groove and bridge it. While the molten metal 20 is piled up, a part of the material 13 is melted and the material 13 is joined to the weld portion.

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 laterally. 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.

Further, since the material 13 is made of the same kind of material as the reinforcing bars 11 and 12 such as ordinary steel, a part thereof is melted by receiving the welding heat, and the weld metal between the joining surfaces and the upper and lower reinforcing bars 11 and 12 are joined. It joins the part near the joining surface.

As a result, the material 13 becomes a part of the joint after the welding is completed and reinforces the joint.

It is necessary that the strength of this material 13 is not higher than that of the reinforcing bars 11 and 12 that are the base materials. When the strength of the material 13 is higher than that of the reinforcing bars 11 and 12, the influence of stress concentration due to the discontinuity of the cross section becomes large, and there is a possibility that the joint may break.

As described above, in order to form the bridging using the bar 13, the both ends of the lower bar 12 of the bar 13 in the circumferential direction are rebar.
The central angle θ with the axis of 12 must 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, this material 13 has a central angle θ of approximately 150 (150/3
60) Stop so that it covers an area of less than °.

The distance d (mm) between the upper reinforcing bar 11 and the material 13 is 2 to D /
2mm However, D (mm) is the distance between the upper reinforcing bar 11 and the lower reinforcing bar 12. 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, if d 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 1 mm or less and b is 1 to 2 mm, the same effect as that of 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; SD40 (JIS) Reinforcing bar shape; JIS G3112 (Steel bar for reinforced concrete) Reinforcing bar diameter; D38 welding rod; JISD7016 Groove space; 12mm and 16mm This material; Width 25mm, length 20mm, thickness 10mm SM41 Material (tensile strength 48 or 46 kg / mm ² ) SB46M material (tensile strength 56 kg / mm ² ), S50C (comparative example, tensile strength 80 or 81 kg / mm ² ) Welding current: 150 to 170 A Welding under these welding conditions The characteristics of the welded portion obtained in the above case are shown in Table 1 below.

In both cases, when the tensile strength of this material is smaller than the strength of the reinforcing bar, it has sufficient strength and ductility.

Further, Table 2 below shows the results of comparison between the case of welding by the method of the embodiment of the present invention and the case of welding by the conventional method using D41 rebar having a diameter of 41 mm, particularly in terms of performance. It is a thing.

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 only necessary to form a joint surface perpendicular to the axial direction on 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, since this material made of steel becomes a part of the joint, the joint strength is reinforced and the reliability of the joint is significantly improved.

Furthermore, it is not necessary to grind the reinforcing bars to be joined together, and it is possible to construct a joint for the restricted reinforcing bars.

Also, the gap between the upper welded material and this material is 2 mm or more,
In addition, since the distance between the upper and lower joint surfaces of the materials to be welded is 1/2 or less, slag is reliably discharged from the gap between the materials to be welded and this material, and bridges are easily bridged within the groove. The part can be formed and the joint can be completed, which results in a sound joint with no welding defects.

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 alloy, 15; Recess

Claims (3)

[Claims] 1. A pair of materials to be welded, which are rod-shaped and whose joint surface is substantially perpendicular to the axial direction thereof, are arranged vertically with a predetermined groove space provided between the joint surfaces, and have a high strength. The material to be welded, which is substantially the same as or less than the material to be welded, is brought into contact with the side surface of the material to be welded below, and is arranged so as to surround a part of the groove space. A gap of at least 2 mm and not more than half the distance between the joint surfaces of the upper and lower weld materials, and then arc welding between the joint surfaces. Enclosed arc welding method characterized by. 2. The welding is started from an arc-shaped corner formed by the material and a material to be welded below, and weld metal is piled up from the side of the material to be welded below to form a bridging portion. The enclosed arc welding method according to claim 1. 3. The enclosure according to claim 1, wherein the material is in contact with the axis of the lower material to be welded in a region having a central angle of 30 to 150 °. Arc welding method.