JP3079486B2 - Welding apparatus and welding method for square steel pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding apparatus and a welding method for a square steel pipe for automatically butting and welding square steel pipes used as building materials in building construction or the like at a construction site.

[0002]

2. Description of the Related Art Conventionally, the work of welding square steel pipes used at a construction site up and down and welding the joint thereof has been semi-automatic, and requires the skills of a skilled worker. In this case, first, the square steel pipes are butted together, and the upper and lower square steel pipes are temporarily fixed and fixed with an erection piece, and then, for example, two workers move between the erection piece and the erection piece on opposite sides of the square steel pipe. Weld at the same time. This is to prevent the square steel pipe from leaning to one side due to distortion or the like. Next, the erection piece is cut, and the remaining portion is welded simultaneously from both sides in the same manner, and one round of the joint between the upper and lower square steel pipes is welded. At this time, it is necessary to smooth the seam between the end of the bead formed by the first welding and the end of the bead formed by the next welding. In some cases, a smoothing process is performed by a grinder or the like after the welding.

[0003]

The conventional butt-welding apparatus for square steel pipes has a problem that it is semi-automatic and therefore has a low work efficiency, so that it is difficult to promote the work. In addition, since the work is semi-automatic, a skilled and high welding skill is required for the worker. For this reason, it is difficult for a beginner to perform such work, which also causes a problem that the work efficiency is reduced.

In addition, since the opposite sides of the square steel pipe are first welded at the same time, and then the erection piece is cut and the remaining part is welded, the end of the bead formed by both weldings is smoothed. However, there is a problem that the smoothing process by a grinder or the like is required and the work efficiency is further reduced.

The present invention has been made in view of the above circumstances, and it is possible to improve work efficiency by automatically performing butt welding of square steel pipes, and to make corner joints of a bead smooth. It is an object of the present invention to provide a welding device and a welding method for a steel pipe.

[0006]

According to a first aspect of the present invention, a square steel pipe is mounted on one of upper and lower square steel pipes which are abutted with each other, and a joint between the upper and lower square steel pipes. Two L-shaped rails that are symmetric about a central axis and extend along two joints facing each other;
Two carriages for transporting the welding torch by moving on each of the two L-shaped rails, a control device for controlling the operation of the welding torch, the speed of the carriage, and the like; Means for detecting the end of the bead that has already been welded when it is replaced with a welded joint, and the center axis of the square steel pipe among the joints of the upper and lower square steel pipes temporarily fixed by the temporary fixing means The two joints which are symmetrical to each other and are opposed to each other are simultaneously welded, and then the remaining unwelded joints are simultaneously welded.

[0007] The second invention for achieving the purpose of, in the welding method of the corner steel welding the upper and lower corner steel pipe butt each other, each of <br/> above two substantially L-shaped rail Two substantially L-shaped joints which are symmetrical with respect to the central axis of the square steel pipe and are opposed to each other among the joints of the upper and lower square steel pipes by a welding torch mounted on a traveling bogie. A first step of simultaneously performing a first welding operation on the two parts, and attaching the two substantially L-shaped rails to an unwelded portion, and simultaneously performing a second step on the two unwelded substantially L-shaped joints. And a second step of performing a welding operation of
The end of the bead of the two joints to be welded is
Into a cascade and welded by a second welding operation
The end of the bead of the two unwelded joints to be
Welded by the first welding operation with the welding layer of
Welding on the cascaded end of the
It is characterized by the following.

[0008] A third invention is the second invention, further comprising:
Attach the two substantially L-shaped rails to the unwelded joint
The bead already welded in the first step
Characterized by comprising a step of detecting an end portion
It is.

In a fourth aspect based on the second or third aspect, the welding is performed in a state where a voltage is applied between the welding wire of the welding torch and the square steel pipe after the first welding operation is completed. Moving the torch along the path of the two unwelded joints, detecting the position of the end of the bead formed by the first welding operation by the change in voltage or current at that time, and storing this; A second welding operation is performed based on this memory, and a seam between the end of the bead formed in the first welding operation and the end of the bead formed in the second welding operation is automatically formed. I do.

In a fifth aspect based on the second or third aspect, the welding current is constantly measured during the period of the second welding operation, and is formed by the first welding operation based on a change in the welding current. Detecting the position of the end of the formed bead, thereby automatically establishing a seam between the end of the bead formed in the first welding operation and the end of the bead formed in the second welding operation. Form.

[0011]

According to the first aspect of the present invention, there is provided an apparatus having two L-shaped rails symmetrical with respect to the central axis of a square steel pipe and extending along two joints facing each other.
First, of the joints of the upper and lower square steel pipes, two joints that are symmetrical with respect to the central axis of the square steel pipe and are opposite to each other are simultaneously welded,
Thereafter, the two rails are replaced with unwelded portions and the remaining opposing joints are simultaneously welded, whereby the entire circumference of the square steel pipe can be automatically welded. Further, by replacing the two L-shaped rails with the remaining non-welded joints, a bead splicing operation is automatically performed by providing a means for detecting the end of the already welded bead. .

In the method according to the second aspect of the present invention, with the above-described configuration, the first invention apparatus can automatically weld one round of the joined portion of the butted upper and lower square steel pipes.

According to a third aspect of the present invention, in the method described above, the end of the bead is cascaded by a plurality of welding layers by a first welding operation, and the unwelded two-pieces are welded by a second welding operation. The bead seam can be smoothened by welding the bead ends of the two joints to overlap the cascaded ends of the beads welded by the first welding operation with a plurality of weld layers.

In the method according to the fourth and fifth aspects of the present invention, even if two L-shaped rails are replaced with an unwelded portion after the first welding operation, the bead of the welded portion can be formed. The end can be automatically detected and bead joining can be performed, which further promotes automation and labor saving.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of an automatic welding apparatus according to one embodiment of the present invention, and FIG. 2 is a front view thereof. 3 is a perspective view showing a state in which square steel pipes to be welded are butted and temporarily fixed, and FIG. 4 is a plan view showing a state in which rails for an automatic welding device are attached to the square steel pipe. 5 (A) to 5 (D) are sectional views of a square steel pipe showing a procedure of one embodiment for welding one round of a square steel pipe, and FIGS. 6 (A) to 6 (D) show welding of one round of a square steel pipe. It is sectional drawing of a square steel pipe which shows the procedure of other Example performed. Here, as shown in FIG. 3, a case where square steel pipes 10 and 12 used as a building construction material are butted and welded to each other at a welded portion 14 will be described.

Prior to welding, first, the square steel pipes 10 and 12 are butted against each other, and the two are temporarily fixed by an erection piece 16. The erection piece 16 is fixed by bolts or the like (not shown). Then, FIG.
An L-shaped moving rail 18 is fixed to the square steel pipe 10 as shown in FIG. The rails 18 are fixed to the square steel pipe 10 by sandwiching the opposing surfaces of the square steel pipe 10 with fixing means 20 and tightening the bolts 22 so as to be pressed from both sides. In addition, one L-shaped rail is for welding a quarter turn of the square steel pipe, and when actually performing welding, as shown in FIG. 5 and FIG. Two L-shaped rails are arranged on both sides symmetrical with respect to each other.

As shown in FIGS. 1 and 2, a welding carriage 30 and a traveling carriage 34 are provided on the rail 18.
Each of the welding carriage 30 and the traveling carriage 34 is supported by four bearings 32 per set from above and below the rail 18,
This is provided on the other side, that is, in the depth direction of FIG. 1, and is supported by a total of eight bearings. The traveling carriage 34 and the welding carriage 30 are connected to the joint 3.
6 are connected to each other. A rack 38 is provided on the rail 18, and a drivable gear 40 provided on the traveling carriage 34 meshes with the rack 38.
Therefore, by driving the gear 40, the traveling vehicle 34 and the welding vehicle 30 connected thereto can be moved along the rail.

A welding torch 42 for feeding a welding wire 44 from the tip is provided below the welding carriage 30.
The welding torch 42 is a welding torch for gas metal arc welding. In addition to the movement along the rail 18 by the welding carriage 30 (this is defined as the x direction), the welding torch 42 also moves in the y and z directions as shown in FIG. it can. Therefore, the tip of the welding torch 42 can be moved to any position on the workpiece. Further, the welding torch itself can be swung to cause a so-called weaving operation to be performed at the tip end. The welding conditions are determined by the traveling speed of the welding carriage 30, the feed speed of the welding wire 44, and the welding voltage determined according to these values and the welding wire protrusion length.

The welding cart 30 shown in FIG. 1 or FIG.
While moving along the L-shaped rail 18 of the square steel pipe 1
The 0 curved portion and the straight portion are continuously welded. When welding is performed continuously in this manner, it is not necessary to perform bead joining at a boundary between a straight portion and a curved portion. Further, in this embodiment, the optimum welding speed in the curved portion is calculated from the curvature of the curved portion determined in advance so that the height of the bead in the straight portion and the curved portion is uniform, and the speed of the bogie in the curved portion is calculated based on the calculated welding speed. Control means. This is described in detail in a patent application (Japanese Patent Application No. 4-335599) filed by the present applicant. In this embodiment, it is assumed that multi-layer welding is performed, and even when one location is welded, the bead thickness of one bead in one pass is thin, and a predetermined thickness is obtained by overlapping the bead over a plurality of layers.

Next, a procedure for welding a square steel pipe will be described with reference to FIGS. FIG. 5A shows that two L-shaped rails 18 are attached to the joint portion where the erection piece 16 is not provided so as to be symmetrical and opposed to the center axis of the square steel pipe 10 in the manner described with reference to FIG. It shows the state where it was turned on. The surface of the square steel pipe 10 is provided with four ceramic tabs 24 for defining the ends of the weld beads. Although this ceramic tab is for shaping the end of the weld bead, a flux tab can be used instead of the ceramic tab.

When the welding carriage 30 is run on two L-shaped rails 18 provided as shown in FIG. 5A and the welding torch is moved from 42a to 42d in FIG. , The portion 2 shown by hatching in FIG.
The welding for 6a is performed. If the opposing sides are welded at a time in this manner, there is no concern that the square steel pipe will tilt due to the heat during welding, and the erection piece 16 can be removed because it is temporarily fixed by the already welded portion. At this point, the ceramic tab 24 is also removed. Next, as shown in FIG. 5 (C), the L-shaped rail 18 is replaced with an unwelded portion of the square steel pipe, and a welding operation is simultaneously performed on the 26b portions on the opposite sides in the same manner. This finally completes the welding of one round of the square steel pipe as shown in FIG. 5 (D).

The procedure shown in FIGS. 6A to 6D is basically the same as the procedure shown in FIGS. 5A to 5D, but in this case, welding is performed without providing the tab 24. Is different from the procedure of FIG. If the ends of the beads in each layer are extended to the same position without providing the tab, the weld metal in a molten state flows out. Therefore, in this embodiment, the end 27 of the weld bead is inclined obliquely as shown in the enlarged view of FIG. When viewed from above, the end portion 27 has a cascade shape. In order to form the ends of the weld bead in a cascade in this manner, the operation of stacking the layers so that welding is completed before the end of the upper weld layer reaches the end of the lower weld layer is repeated. As shown in FIG.
When the welding of the portion 6a is completed, the remaining portion 26b
Weld the parts. At this time, in contrast to the case of 26a, the operation of repeating welding and laminating each layer is repeated until the end of the upper weld layer goes ahead of the end of the lower weld layer.
In this way, the end of 26a and the end of 26b are
As shown in (B), they overlap each other, and the surface of the finally obtained bead seam becomes smooth.

In the case of FIGS. 5 and 6, 26a
After welding the part, replace the L-shaped rail to 26b
When welding this part, the welding torch 42 needs to know the position of the end of 26a already welded.
In this case, there is a method in which the operator teaches the welding robot to the welding robot by teaching. In the present embodiment, the position of the end of 26a is detected by the following two methods.

The first is a so-called wire touch method.
First, after the welding operation of the portion 26a is completed, the welding torch 42 is moved to the path of 26b before welding with a predetermined voltage applied between the welding wire 44 of the welding torch 42 and the square steel pipe 10 (or 12). Move along. At this time, when the welding wire reaches the end of 26a, the voltage and the flowing current change. By detecting the change in the voltage or the current, the end position of the bead 26a is indirectly detected. Then, this position is stored, and based on this stored information, the welding operation of the portion 26b is performed, and a bead seam is automatically formed at the end of 26a and the end of 26b. By using such a method, automation of welding of the portion 26b is further promoted, work efficiency is improved, and special skill is not required for the operator.

The second method is as shown in FIG. 5 or FIG.
The welding of the portion 26a is started immediately after the welding of the portion 6a and the replacement of the L-shaped rail. During this operation, the welding current is constantly measured, and the end position of the bead 26a is detected based on the change in the welding current, whereby the bead seam is automatically formed at the end of the bead 26a and the end of the bead 26b. That is to form it.
Also in this case, there is an advantage that automation is further promoted, work efficiency is improved, and special skill is not required for the operator.

The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention.

[0027]

As described above, according to the present invention, it is possible to automate the butt welding work of a square steel pipe at a construction work site, which has been conventionally performed almost manually, so that the work efficiency can be improved. It is possible to provide a welding apparatus and a welding method for a square steel pipe which can obtain advantages of improvement, reduction of the number of workers, and stabilization of welding quality, and also do not require skill of an operator.

[Brief description of the drawings]

FIG. 1 is a side view of an automatic welding apparatus according to one embodiment of the present invention.

FIG. 2 is a front view of the automatic welding device shown in FIG.

FIG. 3 is a perspective view showing a state in which square steel pipes as welded objects are butted.

FIG. 4 is a plan view showing a state where rails through which a welding cart and a traveling cart pass are fixed to a square steel pipe.

FIGS. 5A to 5D are plan views illustrating a welding procedure of a square steel pipe when an erection piece is used.

FIGS. 6A to 6D are plan views illustrating a welding procedure of a square steel pipe in a case where an end of a bead is formed in a cascade without using an erection piece.

FIG. 7 is a cross-sectional view showing an end of a cascaded bead.

[Explanation of symbols]

 10, 12 square steel pipe 14 welded portion 16 erection piece 18 rail 20 fixing means 22 bolt 24 ceramic tab 26a, 26b weld bead 27 end of weld bead 30 welding trolley 32 bearing 34 running trolley 36 joint 38 rack 40 gear 42 welding torch 44 Welding wire

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI B23K 37/06 B23K 37/06 R (56) References JP-A-4-351272 (JP, A) JP-A-2-133172 ( JP, A) JP-A-63-252683 (JP, A) JP-A-4-89195 (JP, A) JP-A-59-21479 (JP, A) JP-A-4-70286 (JP, U) 52-23607 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/12 B23K 9/00 B23K 9/028 B23K 9/127 B23K 37/02 B23K 37/06

Claims (5)

(57) [Claims] 1. A method according to claim 1, wherein the upper and lower square steel pipes are attached to one of the upper and lower square steel pipes and are symmetrical with respect to the central axis of the square steel pipe and are opposed to each other. Two L-shaped rails to be extended; two trolleys for transporting the welding torch by moving on each of the two L-shaped rails; and control for controlling the operation of the welding torch, the speed of the trolley, and the like. A device for detecting an end of a bead already welded when the two L-shaped rails are replaced with an unwelded joint, wherein the upper and lower temporarily fixed by temporary fixing means. Welding of square steel pipes characterized by simultaneously welding two joints that are symmetrical with respect to the central axis of the square steel pipe, and then simultaneously welding the remaining unwelded joints. apparatus. 2. A method for welding square steel pipes, wherein the upper and lower square steel pipes are welded to each other , wherein the upper and lower square steel pipes are welded by a welding torch mounted on a truck running on each of two substantially L-shaped rails. At the same time, two substantially L-shaped joints which are located symmetrically with respect to the center axis of the square steel pipe and which are opposed to each other are firstly joined.
A first step of performing a welding operation, the mounting of two rails substantially L-shaped in unwelded portion, two substantially L-shaped unwelded
A second step of performing a second welding operation simultaneously with respect to the junction of the
Two joints that are welded by a first welding operation
The end of the bead is cascaded with multiple weld layers
And the unwelded two pieces to be welded by a second welding operation.
The end of the bead of one joint is first welded by a plurality of weld layers.
Cascaded ends of beads welded by welding operation
A method for welding square steel pipes, wherein the welding is performed so as to overlap with a part . 3. The method for welding a square steel pipe according to claim 2, further comprising joining the two substantially L-shaped rails without welding.
When it is attached to the part, it is already welded in the first step
Detecting the end of the bead
Welding method for square steel pipes. 4. The welding method according to claim 2, wherein after the first welding operation is completed, the welding torch is connected with a voltage between a welding wire of the welding torch and a square steel pipe. By moving along the path of the two unwelded joints, the position of the end of the bead formed by the first welding operation is detected and stored based on the change of the voltage or current at that time, and this storage is performed. Performing a second welding operation based on the above, and automatically forming a seam between the end of the bead formed in the first welding operation and the end of the bead formed in the second welding operation The method for welding square steel pipes according to claim 2 or 3, wherein: 5. The welding method according to claim 2, wherein a welding current is constantly measured during the second welding operation, and the welding current is formed by the first welding operation based on a change in the welding current. Detecting the position of the end of the bead, thereby automatically forming a seam between the end of the bead formed in the first welding operation and the end of the bead formed in the second welding operation; The method for welding a square steel pipe according to claim 2 or 3, wherein: