JP6647437B1 - Pipe welding method and pipe welding equipment - Google Patents

Abstract

An object of the present invention is to provide a pipe welding method capable of understanding welding conditions in all of a plurality of welding stages before performing butt welding of pipes and performing welding of pipes with simple control. A pipe welding method T for welding ends of pipes adjacent in the axial direction in a state where ends of pipes arranged side by side in the axial direction abut against each other. A measuring step of measuring the gap amount between the ends, a centering step of centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference, and welding of the pipe at a plurality of welding stages. And all the welding conditions of the pipes at the plurality of welding stages are set based on the gap amount before performing the welding process. [Selection diagram] FIG.

Description

  The present invention relates to a pipe welding method and a pipe welding device.

2. Description of the Related Art Conventionally, there has been performed a pipe welding method in which pipes arranged side by side in the axial direction are welded in a state where ends thereof are abutted against each other (for example, see Patent Document 1).
In the pipe welding method disclosed in Patent Literature 1, an optimal welding condition database is set in advance for each welding posture of a welding torch and each root gap (gap amount).
When actually performing welding, changes in the welding posture of the welding torch and the root gap width are detected in real time during welding. Then, welding conditions are selected from the optimum welding condition database according to the detected values of the welding posture and the detected values of the root gap, and welding is performed under the selected welding conditions.

JP-A-8-66769

However, in the pipe welding method disclosed in Patent Document 1, welding conditions are determined while measuring the gap amount as needed, and welding is performed with a time lag after the gap amount is measured. Therefore, it is necessary to control the pipe welding apparatus dynamically, which complicates the control.
When the pipe welding method is performed in a plurality of welding stages, the first welding stage performs welding under the welding conditions determined based on the measured gap amount, but the welding conditions in the second and subsequent welding stages. There is a problem that is not determined.

  The present invention has been made in view of such a problem. Before performing butt welding of pipes, the welding conditions in all of a plurality of welding stages can be understood, and welding of pipes can be performed with simple control. It is an object of the present invention to provide a pipe welding method and a pipe welding apparatus that can perform the above.

In order to solve the above problems, the present invention proposes the following means.
The pipe welding method of the present invention is a pipe welding method of welding ends of the pipes adjacent in the axial direction in a state where ends of the pipes arranged in the axial direction are abutted with each other, wherein the shaft is A measuring step of measuring a gap amount between ends of the pipes adjacent in a direction, and a centering step of centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference. Performing a welding step of welding the pipe at a plurality of welding stages, and setting all welding conditions of the pipe at the plurality of welding stages based on the gap amount before performing the welding step. In each of the plurality of welding stages, a welding condition switching angle around the central axis of the pipe is determined before performing the welding process, and the welding process switching angle is determined for each of the plurality of welding stages. Te, wherein the front and rear across a welding condition switching angle by changing the welding conditions, while not straddle the welding condition switching angle is characterized by welding at a constant welding conditions.
Further, the pipe welding method of the present invention is a pipe welding method for welding the ends of the pipes adjacent in the axial direction, with the ends of the pipes arranged side by side in the axial direction abutting each other, A measuring step of measuring a gap amount between ends of the pipes adjacent in the axial direction, and centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference. Performing a welding step of welding the pipe at a plurality of welding stages, and performing all the welding conditions of the pipe at the plurality of welding stages based on the gap amount before performing the welding step. The maximum welding conditions at the maximum gap amount that can weld the pipe without a backing metal and the standard welding conditions at a standard gap amount smaller than the maximum gap amount are set in the welding process. Perform a reference welding condition setting step determined previously, in the measurement step, measure a plurality of the gap amount in the circumferential direction of the pipe, based on the measured plurality of gap amounts, the angle around the central axis of the pipe. The gap amount relational expression that is the relational expression of the gap amount is obtained, and the angle around the central axis of the pipe in which the plurality of gap amounts in the pipe is not measured is estimated based on the gap amount relational expression. Before performing the welding process, the maximum gap amount, the maximum welding condition, the standard gap amount, the standard welding condition, and the estimated gap amount are used to determine welding conditions, and in the welding process, It is characterized by welding under conditions.
Further, the pipe welding apparatus of the present invention is a pipe welding apparatus that welds ends of the pipes adjacent in the axial direction in a state where ends of the pipes arranged side by side in the axial direction abut each other, A measuring unit for measuring a gap amount between the ends of the pipes adjacent in the axial direction, and centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference. Part, a welding part for performing welding of the pipe at a plurality of welding stages, and all the welding conditions of the pipe at the plurality of welding stages, the gap amount before the welding part performs welding of the pipe switching angle defining a welding condition setting unit for setting, in each of the plurality of welding stages, the welding condition switching angle of the center axis of the pipe before the weld performs welding of the pipes based on Comprising a tough, wherein the weld, the welding conditions before and after crossing the switching angle by changing the welding conditions, while not straddle the welding condition switching angle is characterized by welding at a constant welding conditions .
Further, the pipe welding apparatus of the present invention is a pipe welding apparatus that welds ends of the pipes adjacent in the axial direction in a state where ends of the pipes arranged side by side in the axial direction abut each other, A measuring unit for measuring a gap amount between the ends of the pipes adjacent in the axial direction, and centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference. Part, a welding part for performing welding of the pipe at a plurality of welding stages, and all the welding conditions of the pipe at the plurality of welding stages, the gap amount before the welding part performs welding of the pipe And a welding condition setting unit that sets the gap amount based on a plurality of the gap amounts measured by the measuring unit in the circumferential direction of the pipe. On the basis of the, A gap amount calculation unit that obtains a gap amount relational expression that is a relational expression of the gap amount with respect to an angle around the center axis of the pipe, a maximum welding condition at a maximum gap amount capable of welding the pipe without a backing metal, and A welding condition calculating unit that obtains a welding condition relational expression that is a relational expression of the welding condition with respect to the gap amount based on a standard welding condition at a standard gap amount smaller than a maximum gap amount, wherein the gap amount calculating unit includes: Determining an estimated gap amount based on the gap amount relational expression with respect to an angle around the center axis of the pipe in which the plurality of gap amounts in the pipe are not measured; A welding condition for the estimated gap amount is obtained based on a relational expression, and the welded portion is welded under the welding condition.

According to these inventions, the gap amount between the ends of the pipes adjacent in the axial direction is measured, and the pipe center is set so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference of the pipe. Put out. Then, all the welding conditions of the pipes at the plurality of welding stages are set based on the measured gap amount. Therefore, before performing the butt welding of the pipes, the welding conditions at all of the plurality of welding stages can be known.
After setting all the welding conditions, the pipes are welded at a plurality of welding stages. Since there is no need to dynamically set and control the welding conditions by measuring the gap amount of the pipe when welding the pipe, the pipe can be welded with simple control.

Further, it is not necessary to sequentially change the welding conditions of the pipe according to the gap amount. For example, by switching the welding conditions at about 10 positions in the circumferential direction of the pipe, it is possible to perform welding without quality problems. We know from experience of welding. The welding condition switching angle is a value determined based on the welding posture (downward, upright, upward), processing accuracy (gap amount) of the pipe end face, and the like.
This welding condition switching angle is determined before welding the pipe, and in each of the plurality of welding stages, the welding condition is changed before and after the welding condition switching angle is crossed, and the welding condition switching angle is changed. By performing welding under constant welding conditions while there is no straddling, it is possible to avoid complicated control and perform welding of pipes with simpler control.

In addition, by measuring a plurality of gap amounts in the circumferential direction of the pipe and determining a gap amount relational expression that is a relational expression of the gap amount with respect to the angle around the center axis of the pipe based on the plurality of measured gap amounts, It is not necessary to measure the gap amount at all positions in the circumferential direction (it is sufficient to measure the gap amount at a part of the pipe in the circumferential direction). This makes it possible to measure the gap amount at a plurality of fixed places (for example, three or more places) at once without measuring the gap amount at all positions in the circumferential direction of the pipe, which is necessary for the measurement. You can save time.
Further, by simultaneously measuring a plurality of gap amounts, the amount of misalignment can be grasped, which is effective for centering adjustment.

In the above-described pipe welding method, a maximum welding condition at the maximum gap amount that can be welded, and a standard welding condition at a standard gap amount smaller than the maximum gap amount, perform a standard welding condition setting step to determine before performing the welding process, The welding conditions corresponding to the gap amount can be determined by obtaining the welding condition from the maximum gap amount, the maximum welding condition, the standard gap amount, the standard welding condition, and the estimated gap amount by, for example, a linear function.
By the above method, for example, welding is performed under the welding conditions corresponding to the gap amount at the start of welding (usually, a center angle to be described later is 0 °) under the welding conditions at the start until the next welding condition switching angle. Is reached, the welding condition is switched to the welding condition based on the estimated gap amount of the welding condition switching angle, and welding is performed under the same welding condition corresponding to the estimated gap amount until the next welding condition switching angle. By repeating this in sequence, welding can be performed with simple control.

Further, in the pipe welding method described above, the pipe is adjusted in advance to a gap amount that can be welded without a backing metal, and the gap amount is set to be equal to or less than the maximum gap amount that can be welded without the backing metal. It is possible to weld the entire circumference without it. Copper is typically used for the backing metal, which also allows for welding of materials that do not like copper contamination.
Further, by setting the gap amount at the time of completion of the adjustment as the gap amount for determining the welding conditions, it is not necessary to measure the gap amount again. The gap amount that can be welded without the backing metal is possessed by each contractor as construction know-how.

  Further, in the pipe welding method described above, a plurality of the welding condition switching angles are determined, a plurality of switching angle gap amounts at the plurality of welding condition switching angles are obtained from the gap amount relational expression, and the welding conditions at the plurality of welding condition switching angles are determined. Is determined from the maximum gap amount, the maximum welding condition, the standard gap amount, the standard welding condition, and the plurality of switching angle gap amounts, and in the welding step, welding is performed toward one side in a circumferential direction of the pipe. Performing welding under a constant first welding condition while the first welding condition switching angle, which is one of the plurality of welding condition switching angles, does not straddle in the circumferential direction. Is reached, the welding condition is switched to the second welding condition corresponding to the first welding condition switching angle, the plurality of welding condition switching angles Of to said second welding condition switching angle different from the first welding condition switching angle may perform welding at the second welding condition.

According to the present invention, the switching angle gap amount corresponding to each welding condition switching angle can be accurately obtained from the gap amount relational expression. Then, the welding condition corresponding to the welding condition switching angle can be accurately obtained from the maximum gap amount, the maximum welding condition, the standard gap amount, the standard welding condition, and the switching angle gap amount.
Then, while changing the welding conditions according to the position corresponding to the angle around the central axis at which the pipe is welded, the angle around the central axis is changed by suppressing the change of the welding conditions before and after straddling the welding condition switching angle. As compared with the case where the welding conditions are changed every time, welding of the pipe can be performed with simpler control.

Further, in the above-described pipe welding apparatus, the gap amount is determined based on a maximum welding condition at a maximum gap amount capable of welding the pipe without a backing metal, and a standard welding condition at a standard gap amount smaller than the maximum gap amount. A welding condition calculating unit that determines a welding condition relational expression that is a relational expression of welding conditions with respect to the gap amount calculating unit, based on the gap amount relational expression, determines a switching angle gap amount with respect to the welding condition switching angle, The welding condition calculation unit obtains a switching welding condition for the switching angle gap amount based on the welding condition relational expression, and at a time when the welding unit reaches a portion of the pipe corresponding to the welding condition switching angle. Alternatively, welding may be performed under the above-described switching welding conditions.
According to the present invention, even when the welding condition switching angle is an angle around the central axis corresponding to a position where the gap amount is not actually measured, the welding condition switching angle is switched based on the gap amount relational expression. The angle gap amount can be accurately estimated.
Then, even when the welding condition corresponding to the switching angle gap amount is not directly set, a suitable switching welding condition for the switching angle gap amount accurately estimated based on the welding condition relational expression. You can ask. Therefore, at the time when the pipe reaches the portion corresponding to the welding condition switching angle, welding can be performed under the suitably determined switching welding condition.

In the pipe welding method described above, a position of the pipe that exceeds the largest welding condition switching angle of the plurality of welding condition switching angles to one side in the circumferential direction is defined as a final welding condition switching position, and the final welding The welding conditions may be changed before and after straddling the condition switching position in the circumferential direction.
In the above-described pipe welding apparatus, the pipe welding apparatus further includes a final switching position setting unit that sets a position of the pipe that exceeds the welding condition switching angle to one side in a circumferential direction of the pipe as a final welding condition switching position, and the welding unit includes: The welding conditions may be changed before and after straddling the final welding condition switching position in the circumferential direction.
According to these inventions, the welding condition is changed based on the final welding condition switching position of the pipe, not the angle around the central axis, and the vicinity of the portion where the welding is completed in the pipe is reliably welded under the constant welding condition. Can be.

  ADVANTAGE OF THE INVENTION According to the pipe welding method and the pipe welding apparatus of the present invention, the welding conditions at all of the plurality of welding stages can be known before performing the butt welding of the pipe, and the pipe can be welded with simple control.

It is a perspective view of a piping welding device of one embodiment of the present invention. It is a front view of the principal part in the welding part of the same pipe welding apparatus. It is a front view explaining the position of the new pipe measured by the sensor of the pipe welding apparatus. It is a longitudinal section of piping for explaining a welding condition change angle. It is a longitudinal cross-sectional view of the piping for demonstrating the gap amount. It is a figure explaining the relation of the gap amount to the angle about the central axis of piping. It is a figure explaining the relation of the welding conditions to the gap amount. It is a flowchart which shows the piping welding method of one Embodiment of this invention. It is a figure explaining change of welding conditions to a center angle by the pipe welding method of this embodiment. It is a figure explaining change of welding conditions with respect to a center angle by the conventional pipe welding method.

Hereinafter, an embodiment of a pipe welding apparatus according to the present invention will be described with reference to FIGS.
As shown in FIG. 1, a pipe welding apparatus 1 of the present embodiment welds ends of pipes P adjacent to each other in an axial direction in a state where ends of pipes P arranged in an axial direction are abutted with each other. . Hereinafter, among the plurality of pipes P, the pipes P already joined to each other may be referred to as existing pipes P1, and the pipes P newly joined to the plurality of existing pipes P1 may be referred to as new pipes P2. The existing pipe P1 is configured by joining a plurality of new pipes P2.
The pipe welding apparatus 1 is used in a pipe laying line provided on a pipe lay barge (laying ship) in order to perform a method generally called a lay barge method. The pipe laying line includes a plurality (four in the present embodiment) of welding stages S1, S2, S3, and S4. The number of welding stages provided in the pipe laying line is not particularly limited as long as it is plural. Hereinafter, when the welding stages S1, S2, S3, and S4 are not distinguished, they are collectively referred to as a welding stage S.
The welding stages S1, S2, S3, S4 are arranged side by side in the transport direction X of the pipe P. The transport direction X is, for example, a direction along a horizontal plane.

The pipe welding apparatus 1 includes a centering unit 10, a measuring unit 20, a transport unit 30, a welding unit 35A, 35B, 35C, 35D, an input / output unit 63, a switching angle setting unit 65, and a final switching position setting. A section 66, a welding condition setting section 67, a gap amount calculating section 69, and a welding condition calculating section 71 are provided. Hereinafter, when the welded portions 35A, 35B, 35C, and 35D are not distinguished, they are collectively referred to as welded portions 35.
The centering unit 10 centers the new pipe P2 such that a gap amount, which will be described later, measured by the measuring unit 20 is equal to or less than a predetermined allowable gap amount over the entire circumference of the new pipe P2. The gap amount measured by the measuring unit 20 here refers to a gap amount G in the transport direction X between the outer peripheral surfaces of the pipes P adjacent to each other in the transport direction X, as shown in FIG. FIG. 5 shows an example in which the groove formed between the pipes P adjacent in the transport direction X is a J-shaped (U-shaped) groove.

  Further, the allowable gap amount means a gap amount G that is allowable when welding the butted pipes P without backing metal. When a groove having a predetermined shape is formed between the pipes P adjacent to each other in the transport direction X, a root gap amount G0 that is a length of a short portion of the groove that has the shortest distance in the transport direction X; There is a certain relationship with the gap amount G. For example, the root gap amount G0 corresponding to the allowable gap amount of the gap amount G is a predetermined value of 0.1 mm or more and 0.5 mm or less.

As shown in FIG. 1, the centering unit 10 includes a pair of first transport bodies 11, a centering drive unit 12 that moves a rotating shaft (not shown) of the pair of first transport bodies 11, and a centering unit. And a centering control unit 13 for controlling the driving unit 12.
The pair of first transport bodies 11 are arranged side by side at an interval in the transport direction X. The new pipe P2 is transported so that the axial direction of the new pipe P2 is along the transport direction X. The first transport body 11 transports the new pipe P2 toward the downstream side in the transport direction X.
Each of the first transport bodies 11 includes a base 15 arranged on a pipe laying line, a rotation shaft rotatably supported on the base 15, and a rotation drive for rotating the rotation shaft with respect to the base 15. And a first roller 16 fixed to a rotating shaft.
The rotation axis extends along a horizontal plane and in an orthogonal direction Y that is a direction orthogonal to the transport direction X.
The rotation drive unit is a motor or the like, and rotates the rotation axis around an axis along the orthogonal direction Y.

The centering drive unit 12 includes a drive motor, a two-axis stage, and the like. The centering drive unit 12 is attached to each first transport body 11. The biaxial stage supports the rotation axis of the first carrier 11 so as to be movable in the vertical direction Z and the orthogonal direction Y, respectively. The drive motor moves the rotation axis in the vertical direction Z and the orthogonal direction Y.
The centering control unit 13 includes an arithmetic circuit such as a CPU (Central Processing Unit) and a memory such as a RAM (Random Access Memory). The memory stores a predetermined allowable gap amount and the like.
The centering control unit 13 is connected to each centering drive unit 12. The centering control unit 13 drives each centering drive unit 12 based on the measurement result by the measuring unit 20.

The measurement unit 20 includes a ring body 21 attached to an end of the new pipe P2, and a sensor 22 and an output unit 23 provided on the ring body 21.
The ring body 21 is detachably attached to an end of the new pipe P2 facing the existing pipe P1.
As the sensor 22, for example, a laser line sensor (band laser sensor) is suitably used. As illustrated in FIG. 5, the sensor 22 includes a gap amount (distance) G between the ends of the pipes P adjacent in the transport direction X (in the transport direction X between the outer peripheral surfaces of the pair of pipes P adjacent in the transport direction X). Length). The measurement unit 20 includes a plurality (four in the present embodiment) of sensors 22. The plurality of sensors 22 are arranged at equal angles around the axis of the ring body 21. The measurement unit 20 measures a plurality of gap amounts in the circumferential direction of the pipe P. The plurality of sensors 22 are connected to the output unit 23 by wiring or the like.

For example, the plurality of sensors 22 measure the gap amount G at the upper end P6, the side ends P7, P8, and the lower end P9 of the new pipe P2 shown in FIG.
As shown in FIG. 1, the output unit 23 is connected to the centering control unit 13 of the centering unit 10. The output unit 23 sends the measurement results of the plurality of sensors 22 to the centering control unit 13.

The transport section 30 includes a plurality of second transport bodies 31 configured similarly to the first transport body 11, and an internal clamp (holding section) 32. The plurality of second transport bodies 31 are arranged side by side at intervals in the transport direction X.
The internal clamp 32 has a known configuration, and is disposed in the pipe P. The internal clamp 32 detachably connects the existing pipe P1 and the new pipe P2.

As shown in FIGS. 1 and 2, the welding portion 35A includes a guide rail 36A, a first head 37A, a second head 38A, a wire feeder 39A, a welding power source 40A, and a shielding gas supply unit (not shown). And a welding control unit 41A.
The guide rail 36A is formed in an annular shape whose inner diameter is substantially equal to the outer diameter of the pipe P. The guide rail 36A is detachably attached to the end of the existing pipe P1.
The first head 37A and the second head 38A move along the guide rail 36A.
As shown in FIG. 2, the first head 37A includes a head body 44A, a transport unit (not shown) attached to the head body 44A, a first front torch 45A, and a first rear torch 46A. I have.

The transport unit includes wheels arranged on the guide rail 36A, and a wheel drive motor for rotating the wheels. By driving the wheel drive motor to rotate the wheels, the first head 37A moves on the guide rail 36A to one side D1 (in the circumferential direction) around the center axis O1 of the pipe P. The first head 37A moves over approximately half the circumference of the pipe P from the upper end of the guide rail 36A toward one side D1 around the central axis O1 to the lower end of the guide rail 36A.
The torches 45A and 46A are formed of metal or the like in a tubular shape. A welding wire 48A is disposed in the first front torch 45A. The welding wire 48A is electrically connected to the first front torch 45A.
The first rear torch 46A is arranged on the other side D2 around the center axis O1 than the first front torch 45A. A welding wire 49A is disposed in the first rear torch 46A. The welding wire 49A is electrically connected to the first rear torch 46A.

  The head main body 44A preferably includes a vibrating section that vibrates (weaves) the torches 45A and 46A in the transport direction X with respect to the head main body 44A.

The second head 38A is configured to be plane-symmetric with the first head 37A with respect to a vertical plane including the central axis O1. That is, the second head 38A includes a head body 44A, a transport section, a first front torch 45A, a head body 52A configured similarly to the first rear torch 46A, a transport section, a second front torch 53A of the first head 37A, A second rear torch 54A is provided.
The second head 38A moves from the upper end of the guide rail 36A toward the other side D2 around the central axis O1 to the lower end of the guide rail 36A over about half a circumference of the pipe P. A welding wire 56A is disposed in the second front torch 53A. A welding wire 57A is arranged in the second rear torch 54A.
As shown in FIG. 1, the centering part 10, the measuring part 20, and the heads 37A and 38A of the welding part 35A are arranged on a welding stage S1 of a pipe laying line. The welding portion 35A performs welding of the newly installed pipe P2 at the welding stage S1.
In this example, in the welding stage S1, each of the heads 37A and 38A is to be welded over approximately half the circumference of the pipe P. However, in the welding stage S1, each of the heads 37A and 38A may repeat welding a plurality of times over about half the circumference of the pipe P.

In the wire feeder 39A, welding wires 48A, 49A, 56A, and 57A are wound around a drum (not shown). The wire feeder 39A supplies the welding wires 48A and 49A to the first head 37A, and supplies the welding wires 56A and 57A to the second head 38A.
In the welding power source 40A, although not shown, the plus side terminal is electrically connected to the torches 45A, 46A, 53A, 54A of the heads 37A, 38A, and the minus side terminal is electrically connected to the new pipe P2. I have. The welding power source 40A applies a voltage between the torches 45A and 46A of the first head 37A and the new pipe P2. The welding power source 40A further applies a voltage between the torches 53A and 54A of the second head 38A and the new pipe P2.

  The shielding gas supply unit includes a gas cylinder filled with a shielding gas. The gas cylinder is opened and closed by an on-off valve. The gas cylinder is connected to the heads 37A and 38A by piping (not shown). The gas cylinder supplies the shielding gas at the first head 37A between the first front torch 45A and the welding wire 48A and between the first rear torch 46A and the welding wire 49A. The gas cylinder supplies the shielding gas at the second head 38A between the second front torch 53A and the welding wire 56A and between the second rear torch 54A and the welding wire 57A.

The welding control unit 41A is configured similarly to the centering control unit 13. The welding control unit 41A controls the heads 37A and 38A, the wire feeder 39A, and the like.
The welds 35B, 35C, 35D are configured similarly to the weld 35A. The welding portion 35B is disposed on a welding stage S2 of the pipe laying line. The welding portion 35C is arranged on the welding stage S3, and the welding portion 35D is arranged on the welding stage S4.

  Here, the welding conditions depending on the welding position will be described. The welding posture includes downward welding, vertical welding, upward welding, and the like, depending on the direction in which welding is performed. Since the influence of gravity changes depending on the welding posture of the heads 37A and 38A, it is preferable to determine the welding conditions for each welding posture. When welding the new pipe P2 shown in FIG. 4, it is preferable that the welding conditions be determined by the position of the new pipe P2 to be welded around the central axis O1 of the new pipe P2. Here, a reference line L1 extending upward from the central axis O1 is determined. In the present embodiment, the welding condition of the new pipe P2 is determined by setting the angle (the pipe P) between the line connecting the welding position of the groove between the existing pipe P1 and the new pipe P2 and the central axis O1, and the reference line L1. (Hereinafter, referred to as the center angle). In this example, the welding position of the groove means a welding position by the torches 45A, 46A, 53A, and 54A. The angle at which the welding conditions are switched is referred to as a welding condition switching angle. This is the same for the groove formed in the existing pipe P1.

The welding conditions also change depending on the gap amount G of the pipe P shown in FIG. FIG. 5 shows an example in which the shape of the groove formed by joining the pipes P is U-shaped, but the shape of the groove is not limited to this shape.
In order to butt-weld the pipe P without a backing metal, the gap amount G needs to be set to a relatively small value equal to or less than the allowable gap amount. Even when the pipe P is butt-welded without a backing metal, the mass of the welding wire supplied to the groove increases as the gap amount G increases.

Although not shown, the input / output unit 63 includes an input unit such as a keyboard and an output unit such as a liquid crystal display.
The input / output unit 63 sends an input given by a user of the pipe welding apparatus 1 by operating the input unit to the switching angle setting unit 65 and the like.

As shown in FIG. 4, the switching angle setting unit 65 determines the welding condition switching angles θ1, θ2 and the final welding angle θ3 around the central axis O1 of the new pipe P2 in each of the welding stages S1, S2, S3, S4. .
The final switching position setting unit 66 determines the position of the newly installed pipe P2 that exceeds the welding condition switching angles θ1 and θ2 to one side D1 in the circumferential direction as the final welding condition switching position Q1.
For example, from the upper end of the new pipe P2 to a position about the center axis O1 of the new pipe P2 corresponding to the first welding condition switching angle (welding condition switching angle) θ1, the torches 45A and 46A of the first head 37A face downward. Welding under welding conditions corresponding to welding. The torch 45A extends from a position around the central axis O1 of the new pipe P2 corresponding to the welding condition switching angle θ1 to a position about the central axis O1 of the new pipe P2 corresponding to the second welding condition switching angle (welding condition switching angle) θ2. , 46A under welding conditions corresponding to vertical welding. Hereinafter, when the welding condition switching angles θ1 and θ2 are not distinguished, they are collectively referred to as the welding condition switching angle θ.
The second welding condition switching angle θ2 is different from the first welding condition switching angle θ1, and is larger than the first welding condition switching angle θ1. In this example, a plurality of welding condition switching angles θ are set for the newly installed pipe P2. The number of welding condition switching angles determined by the switching angle setting unit 65 is not particularly limited.

The final welding angle θ3 is a central angle corresponding to the lower end of the new pipe P2. The final welding angle θ3 is larger than the second welding condition switching angle θ2.
The final welding condition switching position Q1 is the position of the pipe wall of the new pipe P2 that exceeds the largest second welding condition switching angle θ2 of the welding condition switching angles θ1 and θ2 to one side D1. The circumferential length from the final welding condition switching position Q1 to the position of the pipe wall around the central axis O1 of the new pipe P2 corresponding to the final welding angle θ3 is preferably about several tens mm.
From the position around the central axis O1 of the new pipe P2 corresponding to the second welding condition switching angle θ2 to the position around the central axis O1 of the new pipe P2 corresponding to the final welding angle θ3, the torches 45A and 46A perform upward welding. Weld under the corresponding welding conditions. However, since the position from the final welding condition switching position Q1 to a position around the central axis O1 of the new pipe P2 corresponding to the final welding angle θ3 is the last part of welding by the torches 45A and 46A, the position is around the central axis O1. A welding condition based on the length of the new pipe P2 along the pipe wall (a welding condition of the STOP condition) is used instead of the welding condition based on the welding condition.

The switching angle setting unit 65 sets the welding condition switching angle and final welding angle of the welding condition switching angle θ and final welding angle θ3 of the first head 37A to the second head 38A so as to be substantially plane-symmetric with respect to the vertical plane. Determine the angle. The final switching position setting unit 66 determines the final welding condition switching position for the second head 38A substantially symmetrically with respect to the vertical plane with respect to the final welding condition switching position Q1 of the first head 37A.
The switching angle setting unit 65 determines a welding condition switching angle and a final welding angle for each of the welds 35B, 35C, and 35D. The final switching position setting section 66 determines a final welding condition switching position for each of the welding portions 35B, 35C, and 35D.

The user may input the welding condition switching angle and the final welding angle in the welding unit 35 from the input / output unit 63, and store the switching angle setting unit 65 in the switching angle setting unit 65. The same applies to the final welding condition switching position of the final switching position setting section 66.
The switching angle setting unit 65 determines the welding condition switching angle θ and the final welding angle θ3 before the welding unit 35 welds the pipe P. The final switching position setting unit 66 determines the final welding condition switching position before the welding unit 35 performs welding on the pipe P.

The welding condition setting unit 67 sets all welding conditions of the pipe P at the welding stage S based on the gap amount G before the welding unit 35 welds the pipe P.
Here, examples of welding conditions will be described. In this example, the welding conditions are set for each of the front torches 45A and 53A and the rear torches 46A and 54A based on the gap amount G in each welding stage S.
Here, the standard welding conditions at the standard gap amount where the pipe P can be welded without the backing metal, and the maximum welding conditions at the maximum gap amount where the pipe P can be welded without the backing metal, in the case of the welding stages S1 and S2 Will be described. For example, the standard gap amount is 6.8 mm, and the maximum gap amount is 7.2 mm.
Table 1 shows an example of standard welding conditions in the welding stage S1. The standard welding conditions are welding conditions determined as preferable welding conditions when the gap amount G is the standard gap amount over the entire circumference of the pipe P.

When the center angle is equal to or more than 0 degree and less than 40 degrees which is the first welding condition switching angle θ1, the supply speed of the welding wires 48A and 56A is 11.4 m / min with respect to the welding conditions of the front torches 45A and 53A. Meters per minute). The current flowing through the welding wires 48A and 56A is 268A (ampere). The voltage applied to the welding wires 48A and 56A is 23.5 V (volt). The amplitude of the vibration of the front torches 45A and 53A is 1.0 mm.
Regarding the welding conditions for the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 10.2 m / min. The current flowing through the welding wires 49A and 57A is 250A, respectively. The voltage applied to welding wires 49A and 57A is 24.1V, respectively. The amplitude of the vibration of the rear torches 46A and 54A is 1.9 mm.
The traveling speed of the heads 37A and 38A is 120 cm / min. The frequency of vibration of the torches 45A, 46A, 53A, 54A is 10 Hz (Hertz).

When the center angle is equal to or greater than the first welding condition switching angle θ1 and less than 140 degrees, which is the second welding condition switching angle θ2, for the welding conditions of the front torches 45A and 53A, for example, the supply speed of the welding wires 48A and 56A is: It is 11.8 m / min. Regarding the welding conditions for the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 10.6 m / min.
When the center angle is equal to or greater than the second welding condition switching angle θ2 and equal to or less than 180 degrees, which is the final welding angle θ3, regarding the welding conditions of the front torches 45A and 53A, for example, the supply speed of the welding wires 48A and 56A is 10.8 m. / Min. Regarding the welding conditions of the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 9.6 m / min.
Next, Table 2 shows an example of standard welding conditions in the welding stage S2.

When the center angle is equal to or more than 0 degree and less than 40 degrees which is the first welding condition switching angle θ1, the supply speed of the welding wires 48A and 56A is, for example, 7.3 m / min with respect to the welding conditions of the front torches 45A and 53A. It is. Regarding the welding conditions for the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 7.3 m / min.
When the center angle is equal to or greater than the first welding condition switching angle θ1 and less than 140 degrees, which is the second welding condition switching angle θ2, the supply speed of the welding wires 48A and 56A is 7 with respect to the welding conditions of the front torches 45A and 53A. 0.3 m / min. Regarding the welding conditions for the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 7.3 m / min.
When the center angle is equal to or greater than the second welding condition switching angle θ2 and equal to or less than 180 degrees, which is the final welding angle θ3, regarding the welding conditions of the front torches 45A and 53A, for example, the supply speed of the welding wires 48A and 56A is 7.2 m. / Min. Regarding the welding conditions of the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 7.2 m / min.

Next, the maximum welding conditions at the maximum gap amount will be described. The maximum gap amount is larger than the standard gap amount, for example, 7.2 mm.
Table 3 shows an example of the maximum welding conditions in the welding stage S1. The maximum welding condition is a condition determined as a preferable welding condition when the gap amount G is the maximum gap amount over the entire circumference of the pipe P.

When the center angle is equal to or more than 0 degree and less than 40 degrees which is the first welding condition switching angle θ1, for example, the supply speed of the welding wires 48A and 56A is 11.0 m / min with respect to the welding conditions of the front torches 45A and 53A. It is. Regarding the welding conditions of the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 10.0 m / min.
When the center angle is equal to or greater than the first welding condition switching angle θ1 and less than 140 degrees, which is the second welding condition switching angle θ2, for the welding conditions of the front torches 45A and 53A, for example, the supply speed of the welding wires 48A and 56A is: It is 11.4 m / min. Regarding the welding conditions of the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 10.4 m / min.
Next, Table 4 shows an example of the maximum welding conditions in the welding stage S2.

When the center angle is equal to or more than 0 degree and less than 40 degrees, which is the first welding condition switching angle θ1, the supply speed of the welding wires 48A and 56A is, for example, 7.6 m / min with respect to the welding conditions of the front torches 45A and 53A. It is. Regarding the welding conditions for the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 7.6 m / min.
When the center angle is equal to or greater than the first welding condition switching angle θ1 and less than 140 degrees, which is the second welding condition switching angle θ2, for the welding conditions of the front torches 45A and 53A, for example, the supply speed of the welding wires 48A and 56A is: It is 7.6 m / min. Regarding the welding conditions for the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 7.6 m / min.

Table 5 shows an example of welding conditions (STOP conditions) in all the welding stages S. In this example, the STOP condition is constant regardless of the gap amount G, but the STOP condition may be changed based on the gap amount G.
Further, a range to be welded based on the STOP condition may be provided immediately before the first welding condition switching angle θ1 and immediately before the second welding condition switching angle θ2.

  In the STOP condition, regarding the welding conditions of the front torches 45A and 53A, for example, the supply speed of the welding wires 48A and 56A is 8.5 m / min. Regarding the welding conditions of the rear torches 46A and 54A, the supply speed of the welding wires 49A and 57A is 8.5 m / min.

The welding conditions set by the welding condition setting unit 67 may be input by the user from the input / output unit 63 and stored in the welding condition setting unit 67.
The welding portion 35A changes the welding conditions before and after straddling the welding condition switching angles θ1 and θ2 in the circumferential direction. The welding portion 35A performs welding under constant welding conditions as long as the welding condition switching angles θ1 and θ2 do not straddle in the circumferential direction. The same applies to the welds 35B, 35C, 35D.

As shown in FIG. 6, the gap amount calculation unit 69 is based on a plurality of gap amounts G measured by the measurement unit 20 and is based on a relational expression of the gap amount G with respect to the angle (center angle) about the center axis O1 of the pipe P. Find a certain gap amount relational expression. In FIG. 6, the horizontal axis represents the angle (degree) around the central axis O1 of the pipe P, and the vertical axis represents the gap amount G (mm). The vertical axis of FIG. 6 shows the standard gap amount G1 and the maximum gap amount G2. In FIG. 6, the gap amount G measured by the measuring unit 20 is indicated by a circle, and the gap amount relational expression is indicated by a curve L3. When the measurement unit 20 measures N gap amounts G, it is preferable that the gap amount relational expression be a (N−1) -order function of the center angle (a polynomial function of the order (N−1)). When the measuring unit 20 measures four gap amounts G, the gap amount relational expression is preferably a cubic function of the center angle.
The gap amount calculator 69 calculates the switching angle gap amount with respect to the welding condition switching angle based on the gap amount relational expression.

As shown in FIG. 7, the welding condition calculation unit 71 is a welding equation that is a relational expression of the welding conditions with respect to the gap amount G based on the standard gap amount G1, the standard welding condition C1, the maximum gap amount G2, and the maximum welding condition C2. Find the conditional relational expression. In FIG. 7, the horizontal axis represents welding conditions, and the vertical axis represents gap amount G. The welding condition relational expression is shown by a straight line L4 in FIG.
For example, the welding conditions include the supply speed of the welding wire, the current flowing through the welding wire, the voltage applied to the welding wire, and the like, as described above. Based on the standard gap amount G1, the welding wire supply speed under the standard welding condition C1, the maximum gap amount G2, and the welding wire supply speed under the maximum welding condition C2, the welding wire supply speed is determined by a linear function of the gap amount G. Asking. Then, the supply speed of the welding wire for an arbitrary gap amount G is obtained from the linear function. The current flowing through the welding wire, the voltage applied to the welding wire, and the like are obtained in the same manner.
As described above, the welding conditions for the gap amount G are obtained.
The user may input the standard gap amount G1, the standard welding condition C1, the maximum gap amount G2, and the maximum welding condition C2 stored in the welding condition calculation unit 71 from the input / output unit 63.

The welding condition calculation unit 71 obtains a switching welding condition for the switching angle gap amount based on the welding condition relational expression.
When the welding portion 35 reaches the portion of the pipe P corresponding to the welding condition switching angle, it welds under the switching welding condition.

Next, the pipe welding method of the present embodiment will be described. FIG. 8 is a flowchart illustrating the pipe welding method T of the present embodiment.
First, in a reference welding condition setting step (step T1 shown in FIG. 8), an experiment is performed to determine a standard welding condition C1 for the standard gap amount G1 and a maximum welding condition C2 for the maximum gap amount G2. The determined standard gap amount G1 and the like are input by the user from the input / output unit 63 and stored in the welding condition calculation unit 71. The welding condition calculation unit 71 obtains a welding condition relational expression based on the standard gap amount G1 and the like. The standard welding condition C1 and the maximum welding condition C2 are determined before performing a welding process T7 described later.
When the reference welding condition setting step T1 ends, the process proceeds to step T2.

Next, in the switching angle setting step (step T2), the welding condition switching angle θ in each of the welding stages S is determined and stored in the switching angle setting unit 65. The welding condition switching angle θ is determined before performing a welding process T7 described below.
Note that a new welding condition switching angle that is larger than 0 degrees and that is a center angle corresponding to the final welding condition switching position Q1 and that is different from the welding condition switching angle θ already set may be set.
When the switching angle setting step T2 ends, the process proceeds to step T3.

Next, in the initial step (Step T3), the existing pipe P1 is transported by the transport unit 30 so as to be positioned on the second transport body 31, and the new pipe P2 is arranged on the pair of first transport bodies 11. The ring body 21 of the measuring unit 20 is attached to an end of the new pipe P2 facing the existing pipe P1. The guide rail 36A of the welded portion 35A is attached to the end of the existing pipe P1 facing the new pipe P2. The existing pipe P1 and the new pipe P2 are connected by the internal clamp 32.
When the initial step T3 is completed, the routine goes to Step T5.

Next, in the measurement / centering step (measurement step and centering step; step T5), a plurality of gap amounts G between the ends of the existing pipe P1 and the end of the new pipe P2 adjacent in the axial direction are determined. Measure. In the measurement / centering step T5, the new pipe P2 is further centered such that the gap amount G is equal to or less than the allowable gap amount over the entire circumference of the new pipe P2.
Specifically, a plurality of gap amounts G are measured by a plurality of sensors 22 of the measuring unit 20. In the present embodiment, a plurality of gap amounts G are measured simultaneously. The plurality of measured gap amounts G are sent to the centering control unit 13 via the output unit 23. The centering control unit 13 determines whether each of the plurality of gap amounts G is equal to or less than the allowable gap amount. If each of the plurality of gap amounts G is equal to or less than the allowable gap amount, a gap amount relational expression that is a relational expression of the gap amount G with respect to the center angle is obtained based on the measured plurality of gap amounts G. Hereinafter, this gap amount relational expression is referred to as a first gap amount relational expression.

  An estimated gap amount is obtained based on a gap amount relational expression for a center angle at which the plurality of gap amounts G in the pipe P are not measured. Then, welding conditions are obtained from the standard gap amount G1, the standard welding condition C1, the maximum gap amount G2, the maximum welding condition C2, and the estimated gap amount.

Specifically, the gap amount G at the upper end of the new pipe P2 corresponding to the position where the center angle is 0 degrees is actually measured by the sensor 22. For this reason, the first welding condition (switching welding condition) for welding in the range where the center angle is 0 ° or more and less than the first welding condition switching angle θ1 is determined from the welding condition relational expression for the gap amount where the center angle is 0 °.
Here, the gap amount G of the new pipe P2 corresponding to the position where the center angle is 40 degrees and the gap amount G of the new pipe P2 corresponding to the position where the center angle is 140 degrees are actually measured by the sensor 22. No.

The gap amount calculation unit 69 obtains a first switching angle gap amount (switching angle gap amount) at the first welding condition switching angle θ1 from a gap amount relational expression. Similarly, the second switching angle gap amount (switching angle gap amount) at the second welding condition switching angle θ2 is obtained from the gap amount relational expression.
The welding condition calculation unit 71 obtains a second welding condition, which is a welding condition at the first switching angle gap amount, from a welding condition relational expression. Similarly, a second welding condition, which is a welding condition in the second switching angle gap amount, is obtained from a welding condition relational expression. The welding condition calculation unit 71 obtains the second welding condition and the third welding condition from the standard gap amount G1, the standard welding condition C1, the maximum gap amount G2, the maximum welding condition C2, and the first and second switching angle gap amounts. .
As described above, the welding condition calculation unit 71 sets all the welding conditions of the pipe P at the welding stage S based on the gap amount G and the like before performing the welding process T7 described below.

Here, a method for specifically determining welding conditions will be described with reference to Tables 1 to 4.
The first head 37A of the welding portion 35A performs welding from the upper end of the new pipe P2 toward one side D1, and the welding conditions of the torches 45A and 46A of the first head 37A are specifically as follows. Ask.
A first front torch for performing welding from the upper end of the new pipe P2 using the first front torch 45A to a position around the central axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ1 of 40 degrees, for example. The first welding condition for 45A is obtained as follows. The first welding conditions for the first front torch 45A are based on the welding conditions for the front torch with the welding condition switching angle of 40 degrees in Table 1 and the welding conditions for the front torch with the welding condition switching angle of 40 degrees in Table 3. To determine the welding condition relational expression. The welding condition obtained from the gap amount G measured corresponding to the position where the center angle is 0 degree based on the welding condition relational expression is the first welding condition for the first front torch 45A.

  In order to obtain the first welding condition for the first rear torch 46A, the welding conditions for the rear torch with the welding condition switching angle of 40 degrees in Table 1 and the welding conditions for the rear torch with the welding condition switching angle of 40 degrees in Table 3 are obtained. , A welding condition relational expression is obtained. The welding condition obtained from the gap amount G measured corresponding to the position where the center angle is 0 degree based on this welding condition relational expression is the first welding condition for the first rear torch 46A.

From the position around the central axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ1 using the first front torch 45A, the center of the new pipe P2 corresponding to the second welding condition switching angle θ2 of 140 degrees, for example. The second welding condition for the first front torch 45A for performing welding to a position around the axis O1 is obtained as follows.
A welding condition relational expression is determined based on the welding condition for the front torch with the welding condition switching angle of 140 degrees in Table 1 and the welding condition for the front torch with the welding condition switching angle of 140 degrees in Table 3. An estimated gap amount (first switching angle gap amount) obtained by estimating the gap amount G at a position around the central axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ1 is determined from the gap amount relational expression. At this time, the second welding condition for the first front torch 45A is a welding condition obtained from the first switching angle gap amount based on the welding condition relational expression.

Using the first rear torch 46A, from a position around the central axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ1 to a position around the central axis O1 of the new pipe P2 corresponding to the second welding condition switching angle θ2. The second welding condition for the first rear torch 46A for performing the welding is obtained as follows.
A welding condition relational expression is obtained based on the welding condition for the rear torch with the welding condition switching angle of 140 degrees in Table 1 and the welding condition for the rear torch with the welding condition switching angle of 140 degrees in Table 3. An estimated gap amount (first switching angle gap amount) obtained by estimating the gap amount G at a position around the center axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ1 is obtained from a gap amount relational expression. At this time, the second welding condition for the first rear torch 46A is a welding condition obtained from the first switching angle gap amount based on the welding condition relational expression.

Using the torches 45A and 46A, welding is performed from a position around the central axis O1 of the new pipe P2 corresponding to the second welding condition switching angle θ2 to a position about the central axis O1 of the new pipe P2 corresponding to the final welding angle θ3. The 3 welding conditions and the like are similarly obtained.
From the first welding condition to the third welding condition in the torches 53A and 54A of the second head 38A of the welding portion 35A, the third welding condition and the like are similarly obtained.
The welding conditions for the torches of the first and second heads of the welded portion 35B are similarly obtained using Tables 2 and 4. The welding conditions for the torches of the first and second heads of the welding portions 35C and 35D are similarly obtained.
As described above, all the welding conditions for the groove (hereinafter, referred to as a first groove) between the existing pipe P1 and the new pipe P2 are obtained. After the measurement / centering step T5 is completed, the process proceeds to step T7.

When the centering control unit 13 determines that at least a part of the plurality of gap amounts G exceeds the allowable gap amount, the centering control unit 13 causes the centering driving units 12 of the pair of first transport bodies 11 to rotate the rotation axis. The tube is moved in the up-down direction Z and the orthogonal direction Y, and the position of the new pipe P2 with respect to the existing pipe P1 is appropriately adjusted. A plurality of sensors 22 measure a plurality of gap amounts G, and the centering control unit 13 determines whether each of the plurality of gap amounts G is equal to or less than an allowable gap amount. The process is repeated until the unit 13 determines that each of the plurality of gap amounts G is equal to or smaller than the allowable gap amount.
In addition, after adjusting the misalignment HL (the radial distance between the outer peripheral surfaces of the pair of pipes P adjacent to each other in the transport direction X) shown in FIG. 5 to an allowable value or less, the centering of the new pipe P2 may be performed. preferable.

Next, in the welding step (step T7), the pipe P is welded at the welding stage S.
In the welding step T7 of the welding stage S1, the welding portion 35A performs welding between the existing pipe P1 and the new pipe P2 based on the plurality of measured gap amounts G. The welding portion 35A changes the welding conditions for welding the existing pipe P1 and the new pipe P2 before and after the center angle with respect to the position where the existing pipe P1 and the new pipe P2 are welded crosses the welding condition switching angle θ. The welding portion 35A welds the existing pipe P1 and the new pipe P2 under constant welding conditions as long as the center angle with respect to the position where the existing pipe P1 and the new pipe P2 are welded does not cross the welding condition switching angle θ.

  Specifically, the first head 37A is positioned from the upper end of the new pipe P2 toward one side D1 around the central axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ1 of, for example, 40 degrees. Until then, welding is performed on the torches 45A and 46A under the first welding conditions using the torches 45A and 46A. As long as the torches 45A and 46A do not straddle the first welding condition switching angle θ1 in the circumferential direction, the first head 37A performs welding under the first welding conditions that correspond to the center angle at the upper end of the new pipe P2. Do.

Next, the first head 37A moves the new pipe P2 corresponding to the second welding condition switching angle θ2 from the position around the central axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ1 toward one side D1. Is welded to the torches 45A, 46A using the torches 45A, 46A under the second welding conditions up to the position around the central axis O1 of the above.
That is, the first head 37A changes the welding conditions of the torches 45A, 46A to the first welding condition when the torches 45A, 46A reach the position around the central axis O1 of the new pipe P2 corresponding to the first welding condition switching angle θ. Switching to the second welding condition corresponding to the condition switching angle θ. The torches 45A and 46A perform welding under the second welding condition until the torches 45A and 46A reach a position around the central axis O1 of the new pipe P2 corresponding to the second welding condition switching angle θ2.

Next, the first head 37A moves the torches 45A and 46A from the position around the central axis O1 of the new pipe P2 corresponding to the second welding condition switching angle θ2 toward one side D1 to the final welding condition switching position Q1. Welding is performed on the torches 45A and 46A under the third welding conditions.
Next, the first head 37A uses the torches 45A and 46A from the final welding condition switching position Q1 toward one side D1 to a position around the central axis O1 of the new pipe P2 corresponding to the final welding angle θ3. Welding is performed under the STOP conditions for 45A and 46A. That is, the first head 37A changes the welding conditions before and after straddling the final welding condition switching position Q1 in the circumferential direction.

Note that, in the case where the welding condition relational expression is simplified irrespective of the welding position, a difference between the present embodiment and a conventional control method of the pipe welding method will be described.
FIG. 9 shows changes in welding conditions with respect to the center angle according to the pipe welding method of the present embodiment. In FIG. 9, the horizontal axis represents the center angle (degree), and the vertical axis represents the welding conditions. As shown in FIG. 6, there is a relationship between the center angle and the gap amount G according to a gap amount relational expression shown by a curve L3, and as shown in FIG. There is a relationship based on the welding condition relational expression. In this case, as shown in FIG. 9, there is a relationship shown by a curve L6 similar to the curve L3 between the center angle and the welding conditions.

  In the pipe welding method of the present embodiment, the welding condition when the center angle reaches 0 degree and the position around the center axis O1 of the new pipe P2 corresponding to the welding condition switching angles θ1 and θ2 is expressed by a welding condition relational expression. Is determined in advance based on the However, the welding conditions when welding the position around the central axis O1 of the new pipe P2 corresponding to the center angle from 0 degrees to the welding condition switching angle θ1 are constant. Position of the new pipe P2 whose center angle corresponds to the welding condition switching angle θ1 to the welding condition switching angle θ2 around the central axis O1, and whose center angle corresponds to the welding condition switching angle θ2 to the final welding angle θ3. The welding conditions when welding the position around the central axis O1 are also constant.

Here, unlike the pipe welding method of the present embodiment, a case where the welding condition is obtained based on the welding condition relational expression every time the center angle changes is hereinafter referred to as a welding condition random calculation method. In the welding condition random calculation method, welding conditions based on the welding condition relational expression can be obtained in accordance with the center angle as compared with the pipe welding method of the present embodiment, but the control becomes complicated.
The difference between the welding condition in the pipe welding method of the present embodiment and the welding condition in the welding condition random calculation method is the length along the vertical axis of the region R1 indicated by hatching in FIG. For example, the deviation of the welding condition when the center angle is 90 degrees is the length L7.
When the center angle is 0 degree and the welding condition switching angles θ1 and θ2, there is no divergence between the welding conditions in the pipe welding method of the present embodiment and the welding conditions as needed. Until the center angle reaches the welding condition switching angles θ1, θ2 or the final welding angle θ3, there may be a divergence in the welding state, but the divergence is relatively small.

On the other hand, in the conventional pipe welding method, as shown in FIG. 10, the welding condition is, for example, the standard welding condition C1 until the center angle reaches 0 ° to the final welding angle θ3. Assuming that the welding condition used in the conventional pipe welding method is the standard welding condition C1, the difference between the welding condition in the conventional pipe welding method and the welding condition in the welding condition random calculation method is hatched in FIG. Is the length in the direction along the vertical axis of the region R2. For example, the deviation of the welding condition when the center angle is 90 degrees is the length L8. Generally, the length of the region R2 in the direction along the vertical axis is longer than the length of the region R1 in the direction along the vertical axis.
That is, the welding conditions in the pipe welding method of the present embodiment are closer to the welding conditions in the occasional calculation method than in the conventional pipe welding method.

With the above steps, the welding by the first head 37A is completed.
Next, the second head 38A performs welding from the upper end of the new pipe P2 to the lower end of the new pipe P2 toward the other side D2. When the welding by the second head 38A is completed, as shown in FIG. 5, the first layer B1 and the second layer B2 are provided at the portion on the central axis O1 side of the first groove between the existing pipe P1 and the new pipe P2. Is formed. In FIG. 5, the welding layers such as the first layer B1 are indicated by two-dot chain lines.
When the first layer B1 and the second layer B2 are formed in the first groove, the new pipe P2 is joined to the existing pipe P1, and the new pipe P2 is integrated with the existing pipe P1 to become a new existing pipe P1. . The first groove is formed in a new existing pipe P1. The internal clamp 32 is removed from the new existing pipe P1.

At the same time as the welding step T7 of the welding stage S1, the welding step T7 is performed in the welding stages S2, S3, S4. In the welding stages S2, S3, and S4, welding is performed based on the welding conditions obtained based on the gap amount relational expression obtained before the first gap amount relational expression.
When the welding process T7 in all the welding stages S is completed, the process proceeds to step T9.

  In Step T9, it is determined whether or not the existing pipe P1 has a desired length. When the existing pipe P1 has the desired length, it is determined as Yes in Step T9, and all the steps of the pipe welding method T are completed. On the other hand, when the existing pipe P1 does not have the desired length, No is determined in Step T9, and the process shifts to the initial step T3.

In the welding step T7 performed subsequent to the initial step T3 and the measurement / centering step T5, the third layer B3 and the fourth layer B4 shown in FIG. 5 are provided at the first groove in the existing pipe P1 at the welding stage S2. It is formed.
In the welding step T7 performed again after the welding step T7, the fifth layer B5 and the sixth layer B6 shown in FIG. 5 are formed at the first groove in the existing pipe P1 in the welding stage S3.
Similarly, in the welding stage S4, a final layer (not shown) is formed at the first groove in the existing pipe P1.
Through the above steps, the pipes P constituting the first groove are completely connected to each other.
By repeating the initial step T3, the measurement / centering step T5, and the welding step T7 as a set, the existing pipe P1 becomes longer in the transport direction X and has a desired length.

As described above, according to the pipe welding method T and the pipe welding apparatus 1 of the present embodiment, the gap amount G between the ends of the pipes P adjacent in the transport direction X is measured, and the gap amount G The pipe P is centered so as to be equal to or less than a predetermined allowable gap amount over the entire circumference of P. Then, all the welding conditions of the pipe P at the plurality of welding stages S are set based on the measured gap amount G. Therefore, before performing the butt welding of the pipe P, the welding conditions in all the plurality of welding stages S can be known.
After setting all the welding conditions, the pipe P is welded at the plurality of welding stages S. When welding the pipe P, there is no need to dynamically set and control the welding conditions by measuring the gap G of the pipe P, so that the pipe P can be welded with simple control.

  In the pipe welding method T, the welding condition switching angle θ is determined before performing the welding step T7, and the pipe welding apparatus 1 includes a switching angle setting unit 65 that sets the welding condition switching angle θ. Then, in the plurality of welding stages S, the welding conditions are changed before and after the welding condition switching angle θ is straddled, but welding is performed under constant welding conditions while the welding condition switching angle θ is not straddled. Thereby, while changing the welding conditions in accordance with the position corresponding to the angle around the central axis O1 at which the pipe P is welded, the change in the welding conditions is suppressed before and after the welding condition switching angle θ, and complicated control is performed. By avoiding this, the pipe P can be welded with simpler control.

After obtaining the gap amount relational expression, the estimated gap amount, and the welding conditions, welding is performed under the welding conditions in the welding step T7. Even at a position corresponding to a predetermined angle around the center axis O1 of the pipe P, where the gap amount G is not actually measured, the estimated gap amount is calculated based on the gap amount relational expression, so that the gap amount G can be accurately determined. Can be estimated well. Then, based on the estimated gap amount accurately estimated, the standard gap amount G1, the standard welding condition C1, the maximum gap amount G2, and the maximum welding condition C2, the welding process T7 is performed on the suitable welding condition at the corresponding position. It can be obtained before and can be welded under these welding conditions in the welding step T7.
By performing welding based on the estimated gap amount, it is possible to ensure the quality of welding and suppress an increase in welding time.
Since there is no need to actually determine or store welding conditions for the gap amount G other than the standard gap amount G1 and the maximum gap amount G2, the capacity of the memory required for the pipe welding apparatus 1 can be reduced, and the like. The pipe P can be welded by control.

  The pipe welding device 1 includes a gap amount calculator 69. Even at a position corresponding to a predetermined angle around the center axis O1 of the pipe P, where the gap amount G is not actually measured, the estimated gap amount is calculated based on the gap amount relational expression, so that the gap amount G can be accurately determined. It can be estimated well.

The switching angle gap amount at the welding condition switching angle θ is obtained from the gap amount relational expression, and the welding condition at the welding condition switching angle θ is obtained from the switching angle gap amount and the welding condition relational expression obtained from the gap amount relational expression. Therefore, the switching angle gap amount corresponding to each welding condition switching angle θ can be accurately obtained from the gap amount relational expression. Then, the welding condition corresponding to the welding condition switching angle can be accurately obtained from the welding condition relational expression and the switching angle gap amount.
Then, while changing the welding conditions according to the position corresponding to the angle around the central axis O1 at which the pipe P is to be welded, the change in the welding conditions is suppressed before and after straddling the welding condition switching angle θ. The welding of the pipe P can be performed with simpler control as compared with the case where the welding conditions are changed each time the angle changes.

  If the welding condition relational expression is not obtained, only the welding conditions near the standard gap amount G1 and the welding conditions near the maximum gap amount G2 are known. By obtaining the welding condition relational expression, the welding conditions between the standard gap amount G1 and the maximum gap amount G2 can also be obtained with high accuracy.

The pipe welding apparatus 1 includes a welding condition calculation unit 71. The gap amount calculating section 69 calculates a switching angle gap amount, and the welding condition calculating section 71 calculates a switching welding condition. Then, when the welding portion 35A reaches the portion of the pipe P corresponding to the welding condition switching angle θ, welding is performed under the switching welding condition.
With this configuration, even if the welding condition switching angle θ is an angle around the central axis O1 corresponding to a position where the gap amount G is not actually measured, the welding condition switching angle θ is determined based on the gap amount relational expression. The switching angle gap amount with respect to the condition switching angle θ can be accurately estimated.
Then, even when the welding condition corresponding to the switching angle gap amount is not directly set, a suitable switching welding condition for the switching angle gap amount accurately estimated based on the welding condition relational expression. You can ask. Therefore, at the time when the pipe P corresponding to the welding condition switching angle θ is reached, welding can be performed under the suitably determined switching welding conditions.

In the pipe welding method T and the pipe welding apparatus 1, the welding conditions are changed before and after straddling the final welding condition switching position Q1 in the circumferential direction. Therefore, it is possible to change the welding conditions based on the final welding condition switching position Q1 of the pipe P, instead of the angle around the central axis O1, and to reliably weld the vicinity of the portion of the pipe P where welding is completed under constant welding conditions. it can.
Thereby, the shape of the first layer B1 and the like between the final welding condition switching position Q1 and the position around the central axis O1 of the new pipe P2 corresponding to the final welding angle θ3 can be kept constant, and the final layer is formed. It is possible to reduce the amount of work required for grinding after the grinding.

As described above, one embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the configuration can be changed, combined, or deleted without departing from the gist of the present invention. Etc. are also included.
For example, in the above embodiment, the measurement step and the centering step in the measurement / centering step T5 in the pipe welding method T may be performed as separate steps. In the pipe welding method T, it is not necessary to determine the welding condition switching angle θ before performing the welding process T7.
In the pipe welding method T, the reference welding condition setting step T1 may not be performed. In the pipe welding method T, the final welding condition switching position Q1 need not be determined.
The pipe welding apparatus 1 may not include the switching angle setting unit 65, the final switching position setting unit 66, the gap amount calculation unit 69, and the welding condition calculation unit 71.

With respect to the first groove, the first layer B1 and the second layer B2 are formed at the welding stage S1, the third layer B3 and the fourth layer B4 are formed at the welding stage S2, and the fifth layer B5 and the fifth layer B5 are formed at the welding stage S3. The sixth layer B6 was formed, and the final layer was formed at the welding stage S4.
However, the layer formed in each welding stage S is not particularly limited, and, for example, the first layer B1 to the fourth layer B4 are formed in the welding stage S1, the final layer is formed from the fifth layer B5 in the welding stage S2, A layer may not be formed at the welding stages S3 and S4.

DESCRIPTION OF SYMBOLS 1 Pipe welding apparatus 10 Centering part 20 Measurement part 35A, 35B, 35C, 35D Welding part 65 Switching angle setting part 66 Final switching position setting part 67 Welding condition setting part 69 Gap amount calculation part 71 Welding condition calculation part C1 Standard welding condition C2 Maximum welding condition D1 One side G Gap amount G1 Standard gap amount G2 Maximum gap amount O1 Center axis P Piping Q1 Final welding condition switching position S1, S2, S3, S4 Welding stage T Piping welding method T1 Standard welding condition setting step T7 Welding Process θ1 First welding condition switching angle (welding condition switching angle)
θ2 Second welding condition switching angle (welding condition switching angle)

Claims (9)

A pipe welding method of welding ends of the pipes adjacent in the axial direction in a state where ends of the pipes arranged side by side in the axial direction are abutted with each other,
A measuring step of measuring a gap amount between ends of the pipes adjacent in the axial direction,
A centering step of centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference,
A welding step of welding the pipe at a plurality of welding stages,
Do
All of the welding conditions of the pipe in the plurality of welding stages, based on the gap amount before performing the welding process ,
In each of the plurality of welding stages, determine the welding condition switching angle around the central axis of the pipe before performing the welding process,
In each of the welding steps of the plurality of welding stages,
Change the welding conditions before and after straddling the welding condition switching angle,
A pipe welding method in which welding is performed under constant welding conditions as long as the welding condition switching angle is not straddled . A maximum welding condition at a maximum gap amount capable of welding the pipe without a backing metal, and a standard welding condition at a standard gap amount smaller than the maximum gap amount, a reference welding condition setting step to determine before performing the welding step. Do
In the measuring step,
Measure a plurality of the gap amount in the circumferential direction of the pipe,
Based on the plurality of measured gap amounts, a gap amount relational expression that is a relational expression of the gap amount with respect to the angle around the center axis of the pipe,
For the angle around the central axis of the pipe not measuring the plurality of gap amounts in the pipe, the estimated gap amount is determined based on the gap amount relational expression,
Before performing the welding process, the maximum gap amount, the maximum welding conditions, the standard gap amount, the standard welding conditions, and the welding conditions are determined from the estimated gap amount,
In the welding step, welding under the welding conditions ,
A plurality of welding condition switching angles are determined,
A plurality of switching angle gap amounts at the plurality of welding condition switching angles are determined from the gap amount relational expression,
The welding conditions at the plurality of welding condition switching angles, the maximum gap amount, the maximum welding conditions, the standard gap amount, the standard welding conditions, and obtained from the plurality of switching angle gap amount,
In the welding step, welding is performed toward one side in a circumferential direction of the pipe,
As long as the first welding condition switching angle, which is one of the plurality of welding condition switching angles, does not straddle in the circumferential direction, welding is performed under a constant first welding condition,
When reaching the first welding condition switching angle, switching to the second welding condition corresponding to the first welding condition switching angle,
Wherein up to different second welding condition switching angle and the plurality of the first welding condition switching angle of the welding condition switching angle, pipe welding method according to claim 1 for welding in the second welding condition. The position of the pipe that exceeds the largest welding condition switching angle of the plurality of welding condition switching angles to one side in the circumferential direction is a final welding condition switching position,
The pipe welding method according to claim 2 , wherein the welding conditions are changed before and after straddling the final welding condition switching position in the circumferential direction. A pipe welding method of welding ends of the pipes adjacent in the axial direction in a state where ends of the pipes arranged side by side in the axial direction are abutted with each other,
A measuring step of measuring a gap amount between ends of the pipes adjacent in the axial direction,
A centering step of centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference,
A welding step of welding the pipe at a plurality of welding stages,
Do
All of the welding conditions of the pipe in the plurality of welding stages, based on the gap amount before performing the welding process,
A maximum welding condition at a maximum gap amount capable of welding the pipe without a backing metal, and a standard welding condition at a standard gap amount smaller than the maximum gap amount, a reference welding condition setting step to determine before performing the welding step. Do
In the measuring step,
Measure a plurality of the gap amount in the circumferential direction of the pipe,
Based on the plurality of measured gap amounts, a gap amount relational expression that is a relational expression of the gap amount with respect to the angle around the center axis of the pipe,
For the angle around the central axis of the pipe not measuring the plurality of gap amounts in the pipe, the estimated gap amount is determined based on the gap amount relational expression,
Before performing the welding process, the maximum gap amount, the maximum welding conditions, the standard gap amount, the standard welding conditions, and the welding conditions are determined from the estimated gap amount,
In the welding step, a pipe welding method of welding under the welding conditions. A pipe welding apparatus for welding ends of the pipes adjacent to each other in the axial direction in a state where ends of the pipes arranged in the axial direction are abutted with each other,
A measuring unit for measuring a gap amount between ends of the pipes adjacent in the axial direction,
A centering portion for centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference,
A welding portion for welding the pipe at a plurality of welding stages,
A welding condition setting unit that sets all of the welding conditions of the pipe in the plurality of welding stages based on the gap amount before the welding unit performs welding of the pipe,
In each of the plurality of welding stages, a switching angle setting unit that determines the welding condition switching angle around the central axis of the pipe before the welding unit performs welding on the pipe,
Equipped with a,
The weld is
Change the welding conditions before and after straddling the welding condition switching angle,
A pipe welding apparatus for performing welding under constant welding conditions as long as the welding condition switching angle is not straddled . The measuring unit measures a plurality of the gap amounts in a circumferential direction of the pipe,
The gap amount calculation unit according to claim 5 , further comprising: a gap amount calculation unit that obtains a gap amount relational expression that is a relational expression of the gap amount with respect to an angle around a center axis of the pipe based on the plurality of gap amounts measured by the measurement unit. Plumbing welding equipment. Based on the maximum welding condition at the maximum gap amount that can weld the pipe without a backing metal, and the standard welding condition at a standard gap amount smaller than the maximum gap amount, a welding expression that is a relational expression of the welding condition to the gap amount. A welding condition calculation unit for finding a condition relational expression is provided.
The gap amount calculation unit determines a switching angle gap amount for the welding condition switching angle based on the gap amount relational expression,
The welding condition calculation unit determines a switching welding condition for the switching angle gap amount based on the welding condition relational expression,
The pipe welding apparatus according to claim 6 , wherein the welding portion welds under the switching welding condition when reaching the pipe portion corresponding to the welding condition switching angle. A final switching position setting unit that sets the position of the pipe that exceeds the welding condition switching angle to one side in the circumferential direction of the pipe as a final welding condition switching position,
The pipe welding device according to claim 7 , wherein the welding unit changes welding conditions before and after straddling the final welding condition switching position in the circumferential direction. A pipe welding apparatus for welding ends of the pipes adjacent to each other in the axial direction in a state where ends of the pipes arranged in the axial direction are abutted with each other,
A measuring unit for measuring a gap amount between ends of the pipes adjacent in the axial direction,
A centering portion for centering the pipe so that the gap amount is equal to or less than a predetermined allowable gap amount over the entire circumference,
A welding portion for welding the pipe at a plurality of welding stages,
A welding condition setting unit that sets all of the welding conditions of the pipe in the plurality of welding stages based on the gap amount before the welding unit performs welding of the pipe,
With
The measuring unit measures a plurality of the gap amounts in a circumferential direction of the pipe,
The pipe welding device,
Based on the plurality of gap amounts measured by the measurement unit, a gap amount calculation unit that determines a gap amount relational expression that is a relational expression of the gap amount with respect to an angle around the center axis of the pipe ,
Based on the maximum welding condition at the maximum gap amount that can weld the pipe without a backing metal, and the standard welding condition at a standard gap amount smaller than the maximum gap amount, a welding expression that is a relational expression of the welding condition to the gap amount. A welding condition calculation unit for obtaining a condition relational expression,
The gap amount calculation unit determines an estimated gap amount based on the gap amount relational expression with respect to an angle around the center axis of the pipe that does not measure the plurality of gap amounts in the pipe,
The welding condition calculation unit determines a welding condition for the estimated gap amount based on the welding condition relational expression,
A pipe welding device for welding the welding portion under the welding conditions .

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