JPH05161970A - Method for welding - Google Patents

Abstract

PURPOSE:To execute with safety and in a short time the improvement of working efficiency for positioning the tube plate with the water room end plate, the working for groove-matching and the welding at the inside. CONSTITUTION:A tube plate 2 made as one body with the body drum is mounted on a pair of rollers 53a, 53a which have flanges engaging to the surface of nongroove side of the tube plate 2 and which are movable to the mutually differential directions, a water room end plate 3 is mounted on a pair of rollers 53b, 53b which have flanges engaging to the surface of groove and which are movable to the mutually differential directions, the positioning and the groove- matching are executed by moving rollers 53a, 53a and 53b, 53b, and then the butt-welding of the inside surface is executed with a water room end plate inside surface automatic welding device 20 inserted from a man-hole bearing surface 3c of the water room end plate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for welding a tube plate of a water heater and a water chamber mirror by butt welding a tube plate used in a heat exchanger such as a water heater and a hollow water chamber mirror with a hemisphere. It is about.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 9, a heat exchanger such as a feed water heater has a steam inlet account 1a and an opening of a main body 1 through which steam flows is closed by a tube plate 2. In FIG. 2, a water supply inlet account 3a, a water supply outlet account 3b, and a water chamber mirror 3 having a manhole seat 3c are attached by welding.

The water supplied from the water supply entrance account 3a into the water chamber mirror 3 flows through the U-shaped tube 4 in the main body 1 to exchange heat with steam, and then returns to the water room mirror 3 again to supply the water supply account 3b. Get out of.

Conventionally, in the butt-welded portion of the tube plate 2 and the water chamber mirror 3 of the feed water heater, as shown in FIG. 10, the groove is made to be 4 mm by using a plate 5 or the like. However, it is necessary to perform this alignment work while the water chamber mirror 3 is suspended by an overhead crane and to attach the top plate 5 to the outer periphery of the welded portion at eight or more places. It took more than half a day (about 4 hours) for 3 to 4 people to complete welding.

The frame plate 5 attached by this matching work is shown in FIG.
As shown in 11, the tube sheet 2 and the water chamber mirror 3 are welded to the first layer TIG 6
After the bottom welding of the covered arc welding 7 is completed, it is cut and removed by gas cutting. After the removal, the surface of the base metal is flattened with a grinder. The attachment welding and cutting of the top plate 5 and the subsequent grinder finishing work occupy the largest weight in the work of fitting the tube plate 2 and the water chamber mirror 3.

Further, as shown in FIG. 11, the welding method of the welded portion is such that, as shown in FIG. 11, after the first layer TIG welding 6, the covered arc welding 7 is welded in two or three layers, and then the submerged arc welding 8 is performed. Etc., the welding method by one side welding was applied.

However, due to the revision of the law concerning welding applied to pressure vessels such as heat exchangers, in the case of preheating, at the butt weld where the inside diameter of the cylinder exceeds 900 mm, welding is performed from the outside and inside of the cylinder. Mandatory for construction with double-sided welding. Therefore, in the welding of the inner surface (inside welding) of this butt weld, as shown in FIG.
The welding operator 9 enters the water chamber from the manhole seat 3c of the water chamber mirror 3 and uses the welding TIG torch 10 to perform TI by manual welding.
Welding was done by G welding. Reference numeral 11 shown in FIG. 11 indicates a TIG welded portion by this manual welding.

The movement of the worker during the welding work in the water chamber is carried out while rotating the tube sheet 2 and the water chamber mirror 3, which are the objects to be welded, by the turning roller, which is a very bad working place. The above-mentioned inner welding was a welding under these bad conditions.

Further, in this welded portion, it is necessary to preheat the surface of the welded portion to 150 ° C. or higher with a gas burner 12 or the like before the welding operation. Therefore, the ambient temperature in the water chamber mirror 3 is 60
The temperature rises to around ℃. Therefore, even if a person wears heat-resistant protective equipment and the like, as long as an ordinary person, work for a long time has its own limit from the viewpoint of worker's safety.

Further, the inside of the water chamber mirror 3 is not only in such a state of high ambient temperature, but is also a hemispherical surface, and the water supply account 3a is at the feet, and it is a work area in a narrow area. This is the worst working environment, and the welding operator had to perform welding on the inner surface of the water chamber mirror 3 in such a manner as to bulge.

As described above, in the present groove aligning method and welding method, it is not possible to expect shortening of the groove aligning time, shortening of the welding work time and ensuring the safety of the welding operator, and thus a safer and more efficient welding method. Was required to be improved.

[0012]

By the way, the weight of the water chamber mirror 3 of the feed water heater is 5 to 12 tons, and the plate thickness of the welded portion is 50 to 160 mm, which is very large. When the water chamber mirror is fitted to the tube sheet, it is hoisted by using the overhead crane as described above, and the top plate is welded and fixed to the water chamber mirror and the tube sheet while being hoisted by the wire.

However, since it is necessary to match the root gap of this welded portion to 4 mm, the top plate is temporarily welded to the tube plate and the water chamber mirror, and the alignment is performed using a jig and tool called an arrow. After this alignment was completed, the top plates were main welded, but a huge amount of time was spent on the alignment, welding, cutting and removal of the top plates after underlay welding, and the subsequent grinder work on the cut surface. It was Further, since the work is performed under the above-mentioned situation, it is naturally accompanied by danger to the operator, and it is one of the work that requires caution and attention in safety.

The inner diameter of the welded portion between the tube sheet and the water chamber mirror is 13
It is a long weld with a length of 00 mm to 2200 mm and a circumference of about 4000 to 7000 mm. Welding this long weld in a bad working environment as described above is a good welding method in order to secure the safety of the welding operator, improve efficiency, and shorten the welding work time. However, there has been a strong demand for mechanization of the groove alignment work and welding work of this portion.

Therefore, an object of the present invention is to improve the work efficiency by changing the conventional method of using a top plate to a method of using a turning roller, and to improve the work efficiency, and also to improve the inner surface of the tube plate and the water chamber mirror. It is an object of the present invention to provide a welding method for a tube plate of a feed water heater and a water chamber mirror, which enables mechanization of welding work in a safe manner in a short time.

[0016]

SUMMARY OF THE INVENTION The present invention is a method for welding a tube plate of a feed water heater and a water chamber mirror in which a groove is provided and butt-welded to each other. And a collar that is mounted on a pair of first rollers that are movable in mutually different directions and that engages the water chamber mirror with the groove surface,
In addition, it is placed on a pair of second rollers that can move in different directions, and the tube sheet and the water chamber mirror are positioned and grooved via the first roller and the second roller. The inner surface is butt-welded by an automatic welding device inserted from the manhole seat of the room mirror.

[0017]

The tube plate and the water chamber mirror are positioned and aligned on the first roller and the second roller. Therefore, as in the conventional method, the top plate is welded before welding and the top plate is welded after welding. The work of cutting and removing the plate is no longer required, which simplifies the positioning and groove alignment work to improve work efficiency and greatly reduce the required time. Moreover, since the welding work is performed by inserting the automatic welding device inside the water chamber mirror, it is possible to ensure the safety of the worker and improve the work efficiency.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, an apparatus used in one embodiment of the present invention will be described. FIG. 1 is a front view showing the overall configuration of the device. In the figure, 20 is an automatic welding machine for the inner surface of the water chamber mirror, 21 is the lower part of the axial center of the feed water heater, and one side (right side in the figure) of the body barrel 1 is rotatably supported by a motor. A normal turning roller 22 (not shown) is built in, and a receiving roller 22 is disposed in the lower central part in the same axial direction as the turning roller 21 and rotatably supports the manhole seat 3c of the water chamber mirror 3. Is the turning roller 21 and the receiving roller 22
In the middle of the above, a turning roller, which is disposed in the lower center part in the same axial direction and supports the tube plate 2 and the water chamber mirror 3, 24 is a scanning sensor installed on the end face of the tube plate 2.

The water chamber mirror inner surface automatic welding apparatus 20 described above includes a support base 25, a manipulator arm 26 supported by the support base 25 so as to be movable vertically and horizontally, and an end portion of the manipulator arm 26. The bending mechanism 27 is mounted, the welding head 28 is mounted on the bending mechanism 27, a control panel 29, and a welding power source 30.

The support base 25 is composed of a base 31 and a column 32 fixed vertically to the base 31.
A manipulator arm 26 having a rectangular cross section formed in a hollow rectangular shape is supported via a connecting member (not shown) at 32 so as to be movable in the vertical and horizontal directions.

The refracting mechanism 27 is attached to the end of the manipulator arm 26 as shown in FIGS. 2 and 3, and has gears 34, so as to rotate integrally with both ends of the output shaft 33a.
The head tilting motor 33, to which the 34 is attached, and the rotary shaft 35, which is rotatably supported at the end of the manipulator arm 26, are attached to both ends thereof so as to rotate together, and the gear 3
The tilting gears 36 and 36 are meshed with the respective gears 4 and 34, and have upper portions formed in a flat shape, and a head base 37 integrally attached to the upper portions of the tilting gears 36 and 36.

The welding head 28 is supported by a guide roller 38 provided on the head base 37 so as to be movable along the axial direction of the manipulator arm 26, and a rack is mounted on the upper surface thereof.
A head 40 to which the 39 is attached, a vertical movement motor 42 attached to the head base 37, and a gear 41 that meshes with the rack 39 attached to the output shaft 42a, and a head 40 in parallel with the head 40 via a connecting plate 43. A frame body 45 attached with a rack 44 on the upper surface, a torch up-and-down motor 47 attached with a gear 46 that is movably attached to the frame body 45 and meshes with the rack 44 on an output shaft (not shown), Torch up / down motor 47
Attached to the reduction mechanism 47a of the torch
It is composed of a welding torch 49 which is engaged with 48 and is attached so as to be movable in the left-right direction (up-down direction in FIG. 2). In addition,
A CCD camera 50 is attached to the welding torch.

On the other hand, as shown in FIGS. 4 and 5, the turning roller 23 includes a support base 51 and brackets 52a, which are supported on the support base 51 so as to be movable in a direction orthogonal to the longitudinal direction of the tube sheet 2. Rollers rotatably supported by 52a
53a, 53a, and a bracket 52b that is movably supported on the support base 51 in a direction orthogonal to the longitudinal direction of the water chamber mirror 3.
Rollers 53b and 53b rotatably supported by 52b, respectively.
And brackets that are provided under the brackets 52a and 52a, respectively
54a, 54a, a moving screw shaft 55a that is screw-engaged with the catches 54a, 54a, and a moving screw shaft 55a attached to the support base 51.
Roller moving motor 56a for driving
b 54b, 54b respectively provided at the bottom of b 52b, a screw shaft 55b for moving which engages with the screws 54b 54b, and a roller moving for driving the screw shaft 55b for moving, which is attached to the support base 51. It is composed of a motor 56b. Here, the received money 54a, 54
One side a has a left-hand thread and the other side has a right-hand thread. Correspondingly, the moving screw shaft 55a also has a right-hand thread on one side and a left-hand thread on the other side from the center in the longitudinal direction. Similarly, receipt 54b,
One of 54b also has a right-hand thread and the other has a left-hand thread, and one of the moving screw shafts 55b is also a right-hand thread and the other is a left-hand thread from the center in the longitudinal direction. Further, the tube sheet 2 is attached to the rollers 53a and 53b.
To ensure that the water chamber mirror 3 and
Use a structure with a collar. Further, the roller 22a of the receiving roller 22
Is provided with a groove, and a stopper 57 attached to the inlet end of the manhole seat 3c of the water chamber mirror 3 is inserted therein to prevent misalignment of the water chamber mirror 3.

Next, a method of welding the tube sheet 2 and the water chamber mirror 3 using the apparatus having the above configuration will be described. First, in order to align the tube sheet 2 with the water chamber mirror 3, the tube sheet 2 and the water chamber mirror 3 are placed on the turning roller 23 as shown in FIG. At this time, since the tube sheet 2 is completely attached to the body barrel 1, the tube sheet 2 is set on the turning roller 21 and the roller 53a of the turning roller 23. Further, the water chamber mirror 3 includes a roller receiver 22 and a roller 53b of the turning roller 23.
Set on.

In FIG. 4, the groove shape of the butt welded portion of the tube sheet 2 and the water chamber mirror 3 is shown as an example in which the root gap is eliminated. There is an advantage that it is not necessary to make settings and position confirmation is easy.

The groove alignment of the butt welded portion of the tube sheet 2 and the water chamber mirror 3 is performed by the rollers 53a, 53a and 53 of the turning roller 23.
By rotating the motors 56a and 56b for moving the rollers b and 53b respectively, the tube plate 2 or the water chamber mirror 3 is moved up and down for positioning. Where the turning roller 23
Is a turning roller that supports the main body 1 as if it were moved up and down.
Since it is arranged on the center line of the roller receiver 22 that supports the manhole seat 3c and the manhole seat 3c, no special adjustment in the left-right direction is required. However, when the size of the water chamber mirror 3 changes, adjustment is required to change the width between the rollers.

Further, since the groove of the tube plate 2 and the water chamber mirror 3 are processed so as to have the same perimeter of the long side, it is possible to make the adjustment only by the positioning by the vertical movement, and this adjustment is performed by the roller. Change the width of.

After the alignment of the welded portions of the tube sheet 2 and the water chamber mirror 3 is completed as described above, the welding operation is started. This welding work is performed by TIG welding from the inside, and the above-described automatic welding device 20 for the inner surface of the water chamber mirror is used. Before starting welding,
The size of the water chamber mirror 3 to be welded and the distance from the end face of the inlet of the manhole seat 3c to the welding groove on the inner surface of the water chamber mirror 3 are confirmed on the manufacturing drawings, etc., and a simple NC device is provided on the control panel 29. Enter a value in. The position of the starting point is
It can be set arbitrarily.

When a push button switch (not shown) for "welding head insertion" provided on the control panel 29 is pressed, the work is started, and the tip of the manipulator arm 26 is moved to the manhole seat 3c by the control of the simple NC device. The welding head is inserted from the entrance to a set position in the water chamber mirror 3, and then the head tilting motor 33 is driven, and the welding head is passed through the bending mechanism 27.
Rotate 28 by 90 ° from horizontal as shown in FIG. After this, depending on the size of the water chamber mirror 3, a torch vertical movement motor
42 is driven and the welding torch 49 is positioned. Here, since the size of the water chamber mirror 3 varies depending on the scale of the plant, and the size thereof is wide such that the inner diameter is 1300 to 2200 mm, the positioning of the welding torch 49 needs to be changed each time. ..

Therefore, in the case of the water chamber mirror 3 having a size that cannot be accommodated by the vertical movement motor 42, the rack 44 and the gear 46 meshing with the rack 44 are moved vertically by moving the welding torch 49 by driving the torch vertical movement motor 42. Move to and position. FIG. 7 shows a state in which the welding torch 49 is positioned at the groove portion.

The welding torch 49 is for TIG welding, and a tungsten electrode rod is attached to the tip of the electrode. The gap between the tungsten electrode and the groove surface is positioned to be 1.5 to 2.0 mm. During this positioning, the CCD camera 50 attached to the upper part of the welding torch 49
With this, the positioning state is photographed and displayed on a television monitor (not shown) provided on the control panel 29 so that it can be confirmed.

When the positioning is completed as described above, the control panel
Press the "Start Welding" push button switch (not shown) provided on 29. This starts welding. During this welding, the tube sheet 2 and the water chamber mirror 3, which are the objects to be welded, are rotated, which are the turning roller 21 and the turning roller 23.
This is done by rotating the roller 53b. Use a welding speed in the range of 100 to 200 mm / min.

Further, during welding, the water chamber mirror 3 and the tube sheet 2 which are the objects to be welded may move in a direction perpendicular to the welding line, resulting in misalignment. In order to prevent this, a stopper 57 is attached to the inlet end of the manhole seat 3c of the water chamber mirror 3, and this stopper 57 is designed to enter the groove of the roller 22a of the receiving roller 22, but 1.0 to 2.0 mm. In some cases, some misalignment cannot be tolerated.

Therefore, in order to completely prevent the misalignment, the copying sensor 24 is installed on the end face of the tube sheet 2, and the welding can be carried out without any misalignment of the groove portion. In other words, if a misalignment occurs during welding, the torch lateral movement adjuster 48 is driven by the signal from the scanning sensor 24 to cause the welding torch 49 to follow the movement of the tube sheet 2 and the water chamber mirror 3. ..

On the other hand, the gap between the tungsten electrode and the groove surface of the welding torch 49 is positioned so as to be 1.5 to 2.0 mm as described above. During welding, the AVC (automatic voltage of the welding power source 30 side) is set. The arc length is automatically controlled by the adjusting device).

After the welding is completed, a push button switch (not shown) for "reverse welding head" provided on the control panel 29 is pressed to cause the welding head 28 to move in the reverse operation of the "welding head insertion" operation. It begins to return to the outside of the water chamber mirror 3 and automatically stops at the position of the origin to complete the inner automatic welding work.

In this automatic TIG welding, as shown in FIG. 8, a welding torch 49, a welding wire guide 58, and a welding wire 59 are used.
Is done by using the
The inner welding work is completed.

After that, the front side welding is performed, but at the stage when the inner bottom welding 60 is completed, the moving motors 56a and 56b of the turning roller 23 are rotated to move the tube sheet 2 and the water chamber mirror 3 to the rollers 53a ,. 53a, 53b, 53b are separated from each other, and the turning roller 21 on the main body 1 side and the receiving roller 22 on the manhole 3c are received at two positions.

The front side welding is carried out by the submerged arc welding 8. However, since an unmelted portion is generated at the boundary between the inner bottom welding 60 and the front side welding, the first layer welded portion 8a of the submerged arc welding is normally formed. Weld a little higher than the welding current of. The welding of the second and subsequent layers is performed by normal submerged arc welding, and the welding on the front side is completed.

Further, when this welding method is used, the conventional first layer TIG welding 6 and the outer bottom welding 7 are eliminated,
Since the width of the groove can be narrowed (narrow groove), the welding time can be shortened.

Therefore, the following effects can be obtained by using the embodiment configured as described above. (1) Since the turning roller that has a roller with a collar is used for the groove alignment method, there is no need to install and remove the conventional top plate, which greatly reduces setup time, welding work time, and grinder work time, and The material cost of the plate can be reduced. (2) In the water chamber mirror, the ambient temperature is a small area and the ambient temperature is about 60.
Although it is a working place with a bad condition of ℃, there is no work to be done by the worker, and the safety of the worker is secured. (3) Since the welding torch is moved and positioned using a simple NC device, it can be performed by a simple push button operation, and the setup time for welding work can be shortened. (4) Since the narrow groove can be used, the welding time can be shortened. (5) Because it is automatic welding, it does not depend on the skill of the welding operator.
A consistently high quality weld is obtained. In the embodiment described above, the inner automatic welding device is explained by TIG welding, but it can also be carried out by MIG or MAG welding.

[0042]

As described above, according to the present invention, it is possible to easily perform the groove alignment work of the tube plate of the feed water heater and the water chamber mirror without using the top plate, and the welding operator. Since welding work can be performed without entering the water chamber, the worker's safety can be ensured, and the setup time and welding work time can be greatly shortened and the grinder work can be reduced to ensure consistently high quality. It is possible to provide a method for welding a tube plate of a feed water heater and a water chamber mirror, which can obtain the welded part of the above.

[Brief description of drawings]

FIG. 1 is a front view showing the overall configuration of an apparatus used in an embodiment of the present invention.

FIG. 2 is a front view showing a main part of a water chamber mirror inner surface automatic welding device of an apparatus used in one embodiment of the present invention.

3 is a sectional view taken along line AA of FIG.

FIG. 4 is a sectional view of a turning roller of an apparatus used in an embodiment of the present invention.

5 is a side view of the turning roller shown in FIG.

FIG. 6 is an explanatory view showing a state in which the welding head of the water chamber mirror inner surface automatic welding device shown in FIG. 2 is rotated by 90 °.

7 is an explanatory view showing a state in which the welding torch of the welding head of the water chamber mirror inner surface automatic welding device shown in FIG. 2 is positioned.

FIG. 8 is an explanatory view showing a state after the tube sheet and the water chamber mirror have been butt-welded in an embodiment of the present invention by cutting.

FIG. 9 is a sectional view showing the configuration of a feed water heater to which the present invention is applied.

FIG. 10 is an explanatory view showing a state in which the tube plate of the feed water heater and the water chamber mirror are welded before welding by a conventional welding method.

FIG. 11 is an explanatory view showing a welded portion of a tube plate and a water chamber mirror of a feed water heater cut by a conventional welding method.

FIG. 12 is an explanatory view showing the welding work on the tube plate of the feed water heater and the inner surface of the water chamber mirror by the conventional welding method.

[Explanation of symbols]

1 ... Body barrel, 2 ... Tube plate, 3 ... Water chamber mirror, 3c ... Manhole seat, 20 ... Water chamber mirror inner surface automatic welding device, 21, 23 ... Turning roller, 22 ... Receiving roller, 24 ... Copy sensor, 25, 51 ... Supporting base, 26 ... Manipulator arm, 27 ... Bending mechanism, 28 ... Welding head, 29 ... Control board, 30 ... Welding power source, 49 ... Welding torch, 53a, 53b ... Roller.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B23K 101: 14

Claims (1)

[Claims] 1. A method for welding a tube plate of a feed water heater and a water chamber mirror, in which a groove is provided and butt-welded to each other, wherein the tube plate has a collar that engages with a surface on the non-groove side, and is different from each other. A pair of second rollers that are mounted on a pair of first rollers that can move in different directions, have a collar that engages the water chamber mirror with the groove surface, and that can move in different directions. It is placed on the upper side, and the tube sheet and the water chamber mirror are positioned and groove aligned through the first roller and the second roller, and then automatic welding is inserted from the manhole seat of the water wheel mirror. A method for welding a tube plate of a feed water heater and a water chamber mirror, characterized in that the inner surface is butt-welded by a device.