JP2021065894A - Overlay welding device and overlay welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of deformation of a overlay welding apparatus for overlay welding a circular pipe, which is more compact and can be manufactured at a lower cost than the conventional one, or a tube during overlay welding. Providing overlay welding equipment capable of SOLUTION: This is an overlay welding device for overlay welding a circular tube 2, and the circular tube 2 is supported at an intermediate portion between a welding unit portion 14 for overlay welding and the circular tube 2, and the circular tube is supported. The circular pipe support portions 12 and 13 having the end portion as a free end, the feed mechanism for moving the circular pipe 2 and the welding unit portion 14 relatively in the axial direction of the circular pipe 2, and the circular pipe 2 and the welding unit portion 14 are provided. A build-up welding device 1 comprising a rotation mechanism for relatively rotating a cooling medium and a cooling device 16 for circulating a cooling medium in a circular tube 2. [Selection diagram] Fig. 1

Description

The present invention relates to an overlay welding apparatus and an overlay welding method for overlay welding a tubular body.

For example, in a plant in the pulp and paper industry, a black liquor recovery boiler is an indispensable equipment. In recent years, biomass boilers have been attracting attention from the viewpoint of renewable energy utilization, and many have been newly established in the same industry. These various boilers are required to further improve the amount of power generation and the power generation efficiency, and the usage conditions are adopted so as to maximize the capacity of the boiler itself. On the other hand, the inside of the boiler is always in a severe corrosive environment, such as the use of low-quality fuel in which a component that causes corrosion is contained in the fuel. Furthermore, since there is a demand for shortening the maintenance period and reducing costs, the problem of wall thinning due to corrosion and erosion of various boilers has become apparent. For the pipes used inside and around the boiler, it is essential to use a material that is not easily affected by the corrosive environment (hereinafter referred to as "special alloy").
It is difficult to form the pipe itself used in and around the boiler with a special alloy from the viewpoint of cost. On the other hand, a method is used in which a pipe made of a general material is used as the pipe itself, and a special alloy is overlay-welded to the outer surface thereof to form an anticorrosion layer.
Patent Document 1 discloses a technique relating to an anticorrosion method for forming an anticorrosion layer by overlay welding.

JP-A-2019-158167

Conventionally, a build-up welding device for overlay welding a pipe as described above has been used to perform build-up welding by chucking both ends of the pipe. Since the pipes used inside and around the boiler are long pipes, the conventional overlay welding equipment requires a corresponding size (length). In addition, the heat during welding causes the pipe to shrink or deform (bend). Since the pipe is long, the amount of deformation at both ends (the amount of displacement at the other end when one end is used as a reference) is a large value for the contraction or deformation. Therefore, the conventional device for chucking both ends of the pipe requires rigidity and strength sufficient to suppress this large amount of deformation, and the device is also large-scale from this point as well.

In view of the above points, the present invention is a build-up welding device that is more compact and can be manufactured at a lower cost than the conventional one, or a build-up welding device and a build-up that can reduce the amount of deformation of the pipe during overlay welding. It is an object of the present invention to provide a filling welding method.

(Structure 1)
An overlay welding device that performs overlay welding on a circular tube, in which the circular tube is supported at an intermediate portion between the welding unit portion that performs overlay welding and the circular tube, and the end portion of the circular tube is defined as a free end. A circular pipe support portion, a feed mechanism that relatively moves the circular pipe and the welding unit portion in the axial direction of the circular pipe, and a rotation mechanism that relatively rotates the circular pipe and the welding unit portion. A build-up welding device including a cooling device that circulates a cooling medium in the circular tube.

(Structure 2)
The overlay welding apparatus according to claim 1, wherein the cooling medium is a liquid, and the cooling medium is provided with a fine bubble generator for mixing fine bubbles.

(Structure 3)
The rotation mechanism rotates the circular tube around its axis, and allows the circular tube to swing between the support portion of the circular tube and the end portion of the circular tube due to the rotation of the circular tube. The overlay welding apparatus according to claim 1 or 2, further comprising a runout allowable support portion that supports the pipe.

(Structure 4)
4. The configuration according to any one of configurations 1 to 3, wherein the circular tube support portion supports the circular tube at two or more locations, and the relative distance in the axial direction of each support portion is expandable and contractible. Overlay welding equipment.

(Structure 5)
An overlay welding device for overlay welding a tubular body, the welding unit portion for overlay welding, and a feed mechanism for relatively moving the tubular body and the welding unit portion in the axial direction of the tubular body. , A build-up welding device including a cooling device that circulates a cooling medium in the tubular body and a fine bubble generator that mixes fine bubbles into the cooling medium.

(Structure 6)
An overlay welding method for overlay welding a tubular body, wherein the overlay welding is performed while circulating a coolant mixed with fine bubbles in the tubular body.

According to the present invention, a build-up welding device or a build-up welding method capable of reducing the amount of deformation of a pipe during overlay welding, or a build-up welding device or a build-up welding method that can be manufactured more compactly and inexpensively than before. Can be provided.

Schematic block diagram of the overlay welding apparatus according to the embodiment of the present invention A perspective view showing mainly a mechanical portion of the overlay welding apparatus of the embodiment. The figure which shows the result of the overlay welding by the overlay welding apparatus of embodiment The figure which shows the experimental result about the influence of the cooling water temperature The figure which shows the experimental result about the influence of the mixing of fine bubbles in the cooling water Photographs of experiments on the effects of fine bubbles mixed in cooling water

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The following embodiment is an embodiment of the present invention, and does not limit the present invention to the scope thereof.

1 and 2 are views showing the overlay welding apparatus of the present embodiment, FIG. 1 is a block diagram, and FIG. 2 is a perspective view mainly showing a mechanical portion.
The overlay welding device 1 of the present embodiment is an apparatus that performs overlay welding on the outer surface of a long circular pipe 2 used inside or around the boiler.
The overlay welding apparatus 1 includes a frame base 11 that serves as a base for the apparatus, a chuck rotating portion 12 that chucks and rotates the circular pipe 2 at the intermediate portion of the circular pipe 2, and a circular pipe 2 at the intermediate portion of the circular pipe 2. A cooling medium (water in the present embodiment) inside a chuck portion 13 that rotatably chucks, a welding unit portion 14 that performs overlay welding, a welding power supply portion 15 that is a power source for the welding unit portion 14, and a circular pipe 2. ), The fine bubble generator 17 that mixes fine bubbles into the cooling water that circulates inside the circular tube 2, and between the end of the circular tube 2 and the chuck rotating portion 12 or the chuck portion 13. A suspension belt 18 for supporting the circular tube 2 is provided. The operation of each drive unit and each device (welding unit unit 14, cooling device 16, fine bubble generator 17) is controlled by a control unit (not shown in particular).

The chuck rotating portion 12 has a chuck portion that chucks the circular tube 2 in the intermediate portion of the circular tube 2. The chuck portion is configured to be rotatable around the axis of the circular tube 2 while being chucked by inserting the circular tube 2, and is rotationally driven by power (not particularly shown) of a motor or the like.
The chuck portion 13 has a chuck portion that chucks the circular tube 2 (chuck by inserting the circular tube 2) in the intermediate portion of the circular tube 2, and the chuck portion is configured to freely rotate around the axis of the circular tube 2. Has been done. Further, the chuck portion of the chuck portion 13 is configured to be slidable in the axial direction of the circular tube 2.
The chuck rotating portion 12 and the chuck portion 13 function as a circular tube support portion that supports the circular tube 2 in the intermediate portion of the circular tube 2 and has the end portion of the circular tube 2 as a free end. Further, the chuck rotating portion 12 and the chuck portion 13 support the circular tube 2 at two or more places, and the relative distance in the axial direction of each supporting place can be expanded and contracted.
Further, the chuck rotating portion 12 functions as a rotating mechanism for relatively rotating the circular pipe 2 and the welding unit portion 14.

The welding unit portion 14 has a welding torch 141 and a carriage portion 142 that moves the welding torch 141 in the axial direction of the circular pipe 2. The bogie portion 142 moves on the rail 111 provided on the frame base 11, and is driven by power (not particularly shown) of a motor or the like. As a result, a feed mechanism for relatively moving the circular pipe 2 and the welding unit portion 14 in the axial direction of the circular pipe 2 is configured.
Although not particularly shown, the welding unit portion 14 includes a sliding chuck portion that chucks the circular pipe 2 so as to be slidable in the axial direction thereof. The sliding chuck portion has an insertion hole through which the circular tube 2 can be inserted, and has a plurality of rollers (for example, three places every 120 degrees in the circumferential direction) on the inner surface side of the insertion hole. The inscribed circle in contact with each roller is configured to be equivalent to that of the circular tube 2, whereby the circular tube 2 is slidably chucked in the axial direction thereof. By fixing the welding torch 141 to the sliding chuck portion, the structure is such that the distance between the welding torch 141 and the surface (welding target) of the circular pipe 2 is kept constant. The structure may be such that the distance between the welding torch 141 and the surface of the circular pipe 2 can be kept constant. For example, the welding torch 141 may be fixed to a small trolley running on the surface of the circular pipe 2. Good.

The cooling device 16 circulates cooling water inside the circular tube 2, and has a function as a chiller (temperature control device) and a pump. The overlay welding device 1 continuously overlay-welds the outer surface portion of the circular tube 2, and the circular tube 2 which is the base material may melt down if it is not cooled. Therefore, the inside of the circular tube 2 It is cooled by passing water through it.
Although not particularly shown, the cooling device 16 is connected to a water supply channel connected to one end of the circular pipe 2 and a drainage channel connected to the other end. Since the circular pipe 2 rotates, a mechanism for absorbing the rotation is provided in the water supply channel / drainage channel or the cooling device 16.

The fine bubble generator 17 is a device for mixing fine bubbles (fine bubbles such as microbubbles and nanobubbles) into the cooling water, and is connected to the water supply channel (or the cooling device 16). Overlay welding is performed while the cooling liquid mixed with fine bubbles is circulated in the circular tube 2 by the cooling device 16 and the fine bubble generator 17.

As shown in FIG. 2, the suspension belt 18 supports the circular tube 2 so as to suspend it between the end portion of the circular tube 2 and the chuck rotating portion 12 or the chuck portion 13. The suspension belt 18 functions as a runout allowable support portion for supporting the circular tube 2 while allowing runout near the end portion of the circular tube 2 due to the rotation of the circular tube 2.
In the present embodiment, the upper end portion of the suspension belt 18 is fixedly supported (not shown in particular), but the suspension belt 18 may be suspended via an elastic body such as a spring. ..

According to the above configuration, the overlay welding device 1 performs overlay welding on the outer surface of the circular tube 2 while rotating the circular tube 2 around its axis and moving it in the axial direction. As a result, beads are spirally formed on the outer surface of the circular pipe 2 without gaps, and overlay welding W is performed on the entire outer circumference of the circular pipe 2. FIG. 3 is a photograph showing an example in which overlay welding W is applied to the outer periphery of the circular tube 2 by the overlay welding device 1, FIG. 3 (a) is an appearance, and FIG. 3 (b) is a cross section. As shown in FIG. 3, uniform and good overlay welding is performed.
In addition, although the example of spiral build-up welding is taken here, the present invention is not limited to this. For example, overlay welding may be performed linearly in the longitudinal direction of the circular pipe 2, and the circular pipe 2 may be rotated by the bead width for welding every 1 pass. Considering the deformation of the circular tube 2, the spiral welding type of the present embodiment is effective. As the welding method, MIG welding is adopted in the present embodiment, but the present invention is not limited to this, and various welding methods such as TIG welding, plasma welding, PTA welding and laser welding may be used. ..

The overlay welding device 1 is a simple and compact device capable of stably and continuously overlay welding the outer surface portion of a long (for example, more than 8 m) circular tube 2.
In a conventional device that chucks both ends of a pipe and performs overlay welding, a size larger than the length of the pipe is indispensable. On the other hand, in the overlay welding apparatus 1, the chuck rotating portion 12 and the chuck portion 13 support the intermediate portion of the circular pipe 2, and the end portion of the circular pipe 2 is a free end, so that the apparatus is compact. It can be configured.
Further, in the conventional device in which both ends of the pipe are chucked and overlay welded, the stress generated by the contraction and deformation (bending) of the pipe due to the heat during welding is generated based on the total length of the pipe, which is large. .. As a result, the device is required to have high rigidity and strength. On the other hand, in the overlay welding device 1, since the intermediate portion of the circular pipe 2 is supported and the end portion of the circular pipe 2 is a free end, the influence of contraction and deformation (bending) of the pipe is reduced. It is possible to simplify the apparatus.
Specifically, the size of the conventional apparatus in the longitudinal direction exceeds 8 m, but the length of the overlay welding apparatus 1 of the present embodiment in the longitudinal direction is 3 m. In the overlay welding device 1, the welding length at one time is 2 m, and only the portion to be actually welded is fixed. Therefore, it is difficult to grip the material caused by lengthening the device, and the bending due to the material weight is caused. It has cleared issues such as countermeasures and device rigidity associated with material rotation. Further, by flexibly gripping the circular tube 2 protruding from the device with the suspension belt 18, the above-mentioned action and effect due to the free end of the circular tube 2 is not hindered (temporarily, the tube is deformed). Even if rotational runout occurs at the end, the effect can be absorbed). In addition, since the chuck portion of the chuck portion 13 is configured to be slidable in the axial direction of the circular pipe 2 and the relative distance in the axial direction of the support portion of the circular pipe 2 can be expanded and contracted, the circular pipe 2 contracts during welding. The structure is such that there is no problem with the rigidity of the device even if there is.
From the above, the overlay welding apparatus 1 can clear all of the apparatus size, the apparatus rigidity, the cost, and the difficulty of manufacturing the apparatus.

Next, the experimental results on the influence of the temperature of the cooling water circulating inside the circular tube (tubular body) 2 on the deformation of the tube are shown.
In the experiment, using cooling water set at 10 ° C or 60 ° C by a temperature controller, overlay with a length of 1,450 mm with respect to the outer circumference of a tube having a diameter of 63.5 mm, a thickness of 6 mm, and a length of 2 m. Welding was performed, and then the amount of deformation in the direction shown in FIG. 4A was investigated. The result of comparing the amount of deformation after welding is shown in FIG. 4 (b). It was confirmed that when the set temperature of the cooling water was set to 10 ° C. and the cooling water was rapidly cooled, the amount of deformation of the pipe was large, and when the cooling water was set to 60 ° C., the amount of deformation of the pipe was small. That is, it is possible to suppress the amount of deformation by changing the temperature of the cooling water. It is considered that there is an optimum temperature depending on the diameter of the pipe, the welding method, etc., but as a result of multiple trials, it was found that the set temperature of the cooling water is 60 ° C., which causes the least deformation.

Next, the experimental results regarding the influence of the presence or absence of fine bubbles in the cooling water circulating inside the circular pipe 2 on the deformation of the pipe are shown.
Since the overlay welding apparatus 1 of the present embodiment does not mechanically restrain the pipe in the longitudinal direction, the contraction of the pipe after overlay welding tends to be large. Therefore, an attempt was made to improve the cooling performance by mixing ultrafine bubbles (hereinafter referred to as UFB) in the cooling water circulating in the pipe.

experimental method:
Overlay welding was performed using the overlay welding apparatus 1 under the conditions shown in Table 1. In the experiment, a 6.5 m overlay weld with a thickness of 2 mm was performed on the outer surface of a pipe having a total length of 8 m. Twenty pieces were welded without UFB and 20 pieces were welded with UFB, respectively, and the total length before and after welding was measured.

Experimental result:
FIG. 5 shows the test results. From the results, by applying UFB, the amount of shrinkage was reduced by half, and the error for each number was also reduced to about 1/5.
FIG. 6 is a photograph of the surface temperature of the pipe during welding in the above experiment with a thermo camera. It was found that the molten pool portion immediately after welding became smaller, and the cooling capacity was different even though the cooling water was the same at 60 ° C. It is considered that this change in cooling capacity has a great influence on the amount of shrinkage.

As described above, by setting the temperature of the cooling water to 60 ° C., the amount of deformation (bending) of the pipe can be reduced. In addition, by including UFB in the cooling water, the amount of contraction of the pipe can be reduced and the variation thereof can be reduced.

Even if the operation of the power unit such as a motor in various places and each device (welding unit unit 14, cooling device 16, fine bubble generator 17) is controlled by a control unit (not shown in particular). It may be one that is individually operated by a person, or the like.

In the present embodiment, the welding unit portion 14 is moved in the axial direction while rotationally driving the circular pipe 2, but the present invention is not limited to this, and the circular pipe 2 and the welding unit portion are not limited to this. Anything may be used as long as 14 is relatively rotated or moved.
Similarly, the chuck rotating portion 12 is slidable in the axial direction as an example, but the present invention is not limited to this, and the relative distance in the axial direction of each support portion is configured to be expandable and contractible. All you need is.
Further, in the present embodiment, cooling water is taken as an example as a medium for cooling the circular tube 2, but various cooling media may be used.

1. 1. .. .. Overlay welding equipment 12. .. .. Chuck rotating part (circular tube support part, rotating mechanism)
13. .. .. Chuck part (circular tube support part)
14. .. .. Welding unit (feed mechanism)
16. .. .. Cooling device 17. .. .. Fine bubble generator 18. .. .. Suspension belt (swing tolerance support)
2. .. .. Circular tube

Claims (6)

An overlay welding device that performs overlay welding on a circular pipe.
Welding unit for overlay welding and
A circular tube support portion that supports the circular tube in the middle portion of the circular tube and has an end portion of the circular tube as a free end.
A feed mechanism that relatively moves the circular pipe and the welding unit portion in the axial direction of the circular pipe, and
A rotation mechanism that relatively rotates the circular tube and the welding unit,
A cooling device that circulates a cooling medium in the circular tube,
A build-up welding device characterized by being equipped with. The cooling medium is a liquid
The overlay welding apparatus according to claim 1, further comprising a fine bubble generator for mixing fine bubbles into the cooling medium. The rotation mechanism rotates the circular tube around its axis.
Claim 1 or claim 1, wherein a runout allowable support portion for supporting the circular tube by allowing runout due to rotation of the circular tube is provided between the circular tube support portion and the end portion of the circular tube. The overlay welding apparatus according to 2. The method according to any one of claims 1 to 3, wherein the circular tube support portion supports the circular tube at two or more locations, and the relative distance in the axial direction of each support portion is expandable and contractible. The overlaid welding equipment described. An overlay welding device that performs overlay welding on a tubular body.
Welding unit for overlay welding and
A feed mechanism that relatively moves the tubular body and the welding unit portion in the axial direction of the tubular body, and
A cooling device that circulates a cooling medium inside the tubular body,
A fine bubble generator that mixes fine bubbles into the cooling medium,
A build-up welding device characterized by being equipped with. It is a build-up welding method that performs build-up welding on a tubular body.
A overlay welding method characterized in that overlay welding is performed while circulating a coolant mixed with fine bubbles in the tubular body.

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