JPH067935A - Welding device - Google Patents

Abstract

(57) [Summary] [Purpose] Even when the heat transfer tube 2 is drawn into the tube sheet 1, it is possible to perform welding having excellent mechanical properties and corrosion resistance without spending man-hours. [Structure] The welding torch 5 and the welding torch 5 are attached so that the direction of the welding arc can be changed.
The torch moving mechanism 50 that moves the welding torch 5 so that the welding arc moves along the annular boundary portion 23 while moving the welding plate 1 relative to the tube sheet 1;
The camera 15 that captures the image of the
4, the laser processing device 7 for measuring the distance to the boundary 23, and the image processing device 34.
Based on the position of the tube hole obtained by the above and the distance to the boundary portion 23 obtained by the length measuring device 7,
Welding torch position control device 33 that outputs a correction amount to the moving amount of the welding torch 5 by 2 to the welding torch moving mechanism.
And are equipped with.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding device for welding a pipe inserted in a tube hole of a tube sheet to the tube sheet.

[0002]

2. Description of the Related Art Conventionally, as a welding device for welding a heat transfer tube and a tube plate in a heat exchanger, for example, Japanese Patent Laid-Open Publication No. Sho.
Some are described in Japanese Patent Publication No. 9-35250. This welding device includes a welding torch for performing TIG welding, a guide rod to be inserted into a pipe hole, and a guide rod for X, Y, and
It is provided with a manipulator for moving in the Z direction (the X direction is the vertical direction, the Y direction is parallel to the tube sheet and is horizontal, and the Z direction is the vertical direction to the tube sheet). The welding torch is rotatably attached to the guide rod. Further, the guide rod is provided on the manipulator via an elastic body or the like so that it can be slightly moved in the X and Y directions with respect to the manipulator.

When welding the heat transfer tube and the tube plate, the manipulator is driven to insert the guide rod into the target heat transfer tube. At this time, the guide rod cannot be reliably guided to the target heat transfer tube due to a machining position error of the pipe hole, a positioning error of the manipulator itself, and the like only with the mechanism of the manipulator. Correct the position by moving it slightly in the direction. When the guide rod is inserted into the heat transfer tube, the welding torch is rotated around the guide rod, the welding arc is directed from the outside of the heat transfer tube toward the central axis direction, and TIG welding is performed.

By the way, when the tip of the heat transfer tube is projected from the surface of the tube sheet, such welding can be performed immediately, but when the tip of the heat transfer tube is pulled into the tube sheet, Since welding is performed with the guide rod inserted in the pipe hole, the boundary between the pipe and the pipe sheet cannot be directly welded. Therefore, in such a case, chamfer the tube hole and then perform welding or set the welding current high and slow the welding speed until the tip of the heat transfer tube appears on the tube sheet surface side. The heat transfer tube and the tube plate must be welded while melting the tube plate around the tip of the heat transfer tube.

As a conventional welding device having a guide rod, there are those described in JP-A-52-22544 and JP-A-59-223178.

[0006]

However, in such a conventional technique, since the guide rod is used, it is possible to accurately guide the welding torch to the intended welding position, but the heat transfer tube is not inside the tube sheet. If it is pulled in, as described above, in order to sufficiently melt the tube sheet portion,
It is necessary to perform high heat input welding at a high welding current and a low welding speed, and there is a problem that the mechanical properties of the heat transfer tube and the tube sheet are likely to deteriorate. In particular, when welding austenitic or ferritic stainless steel heat transfer tubes and tube sheets, which require corrosion resistance, coarsening of crystal grains in the heat-affected zone and sharpness of the structure due to welding with high heat input. As a result, deterioration of corrosion resistance of the welded portion is likely to occur.

Further, in order to perform welding with a low heat input, in the method of chamfering the tube hole according to the drawn amount of the heat transfer tube and directly melting the boundary between the heat transfer tube and the tube plate, There is a problem that the chamfering process is very troublesome and the man-hours are very large. In this method, when the pipe hole pitch is narrow or the pipe pull-in amount is large, sufficient chamfering cannot be performed, and eventually high heat input welding is executed.

The present invention has been made by paying attention to such a conventional problem, and even when the heat transfer tube is pulled into the tube sheet, welding for the purpose of a welding torch can be performed without spending man-hours. An object of the present invention is to provide a welding device that can be accurately guided to a position and can perform welding with excellent mechanical properties and corrosion resistance.

[0009]

A welding device for achieving the above object is a welding device for welding a plurality of pipes respectively inserted into a plurality of pipe holes of a pipe sheet to the pipe sheet, wherein A welding torch for welding an annular boundary with the tube sheet, the welding torch being mounted so as to be able to change the direction of its welding arc with respect to the boundary, and moving the welding torch relative to the tube sheet. Together with the welding torch moving means for rotating the welding torch so that the welding arc of the welding torch moves along the annular boundary portion, the image pickup means for picking up the image of the tube sheet, and the image pickup means Image processing means for obtaining the position of the tube hole on the tube sheet from the image obtained, length measuring means for measuring the distance to the boundary portion, and based on the position data of the plurality of tube holes obtained in advance. Before The welding torch moving means was controlled so that the welding torch was sequentially guided to the vicinity of the plurality of tube holes, and the position of the tube hole obtained by the image processing means and the length measuring means were obtained. A correction amount for the driving amount so that the welding arc of the welding torch faces the boundary portion based on the distance to the boundary portion and the distance from the tip of the welding torch to the boundary portion becomes a predetermined distance. And a welding torch position control device for outputting the welding torch moving means to the welding torch moving means.

[0010]

OPERATION Here, the operation of welding a pipe whose tip is drawn into the tube sheet will be described. First, the welding torch is initialized so that any one of the plurality of tubes can be welded immediately. In the initial setting of this welding torch, not only the position of the welding torch but also the tip of the welding torch faces outward with respect to the rotation center axis, and the distance between the tip of the welding torch and the annular boundary is suitable for this welding. Set the orientation of the welding torch so that the distance is large.

Subsequently, the welding torch moving means rotates the welding torch and welds the annular boundary portion between the pipe and the tube sheet. At this time, at least the portion to be welded next is imaged by the imaging means, the position of the tube hole to be welded next is determined on the tube sheet, and the distance to the boundary between the tube and the tube sheet is measured by the length measuring means. Measured by. When the first boundary portion is welded, the welding torch is moved by the welding torch moving means on the basis of the position data of a plurality of pipe holes obtained in advance, for example, the NC data for pipe hole processing used at the time of pipe hole processing. Let By the way, when the welding torch is moved only by using such NC data for pipe hole machining, the welding torch is accurately positioned at the boundary portion due to a machining position error during pipe hole machining and a positioning error of the moving mechanism itself. I can't lead. Therefore, based on the position of the pipe hole obtained by the image pickup means and the distance to the boundary portion obtained by the length measuring means, the welding arc of the welding torch faces the boundary portion and the tip of the welding torch reaches the boundary portion at a predetermined distance. Correctly move the welding torch so that it is farther away.

Then, the welding torch is rotated to weld the boundary portion. Also at this time, the image of the portion to be welded next is measured and the length is measured, and the data obtained by this is used for the correction movement of the welding torch in the next welding. The above operation is repeatedly performed to sequentially weld a plurality of tubes to the tube sheet.

As described above, according to the present invention, the position of the welding torch is corrected by actually measuring the position of the welding portion by using the image pickup means and the like, so that the welding torch is located at the boundary portion which is the welding portion. Can be guided accurately. Furthermore, due to the fact that the welding torch can be accurately guided to the welding part,
Since it is not necessary to use a guide rod etc. as in the prior art, the welding arc can be directed outward from the central axis side of the pipe, and even if the tip of the pipe is pulled into the pipe sheet, It is possible to directly weld the boundary portion without chamfering.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a welding device for welding a pipe and a tube sheet according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, the welding apparatus of the present embodiment has a boundary portion 23 between the heat transfer tube 2 having an outer diameter of 15 to 23 mm and the tube sheet 1 of the heat exchanger 60.
TIG welding. This heat transfer tube 2 is a tube plate 1
Is drawn in from the surface of the tube 1 to about 1.2 to 3.0 mm according to the wall thickness of the heat transfer tube, and the boundary portion 23 exists in the tube hole 24.

As shown in FIGS. 1, 2 and 3, the present welding apparatus includes a welding torch 5 for TIG welding a boundary portion 23 between the heat transfer tube 2 and the tube sheet 1, and a welding torch for moving the welding torch 5. A moving mechanism 50, a torch position control device 33 for controlling the welding torch moving mechanism 50, a welding wire feeding device 52 for feeding the welding wire 13 to the vicinity of the tungsten electrode 3 of the welding torch 5, and a TIG welding device. A welding power source 31 for supplying electric power, a welding controller 30 for controlling the welding power source 31, a gas cylinder (not shown) for supplying argon gas as a seal gas, a small camera 15, and an image captured by the camera 15. The image processing device 34 that performs a specific process on the captured image, the laser length measuring device 7 that measures the distance to the boundary portion 23, and the measurement timing by the laser length measuring device 7 are controlled. A laser length controller 37 for temporarily storing the measurement data with the welding torch moving mechanism 50
It is configured to have a triaxial manipulator 22 for moving the triaxial manipulator 22 in three directions (X direction, Y direction, Z direction) and an NC control device 32 for controlling the triaxial manipulator 22.

As shown in FIG. 1, the welding torch moving mechanism 50 includes a torch rotating stepping motor 16 with a speed reducer for rotating the welding torch 5, a rotating motor case 25 supporting the stepping motor 16, and a torch rotating motor. Torch rotating shaft 8 attached to the shaft of 16 and torch Z-direction moving servomotor 1 for moving the welding torch 5 in the Z direction
1, a torch holder 6 that holds the welding torch 5, a gear 9 that is attached to the shaft of the Z-direction moving motor 11, and that engages with a screw 10 formed at one end of the torch holder 6.
An X-direction slide unit 19 for moving the rotation motor case 25 in the vertical direction (X direction) together with the rotation shaft 8, the welding torch 5, etc., and an X-direction movement servo motor 18.
a, a Y slide unit 20 that moves the X direction slide unit 20 in the horizontal direction (Y direction), and a Y direction movement servomotor 18b.

The torch rotation shaft 8 is rotatably supported by a radial bearing 17 provided in a rotation motor case 25. One end of the torch holder 6 is provided inside the rotary shaft 8 and is supported by a bearing 29 so as to be movable in the Z direction while rotating. Therefore, the torch holder 6 and the welding torch 5 are driven by the Z-direction moving motor 11 fixed to the rotary shaft 8 to rotate the gear 9 and the gear 9, and move in the Z direction while rotating. Will be done.

The Z-direction moving servo motor 11, the X-direction moving servo motor 18a, and the Y-direction moving servo motor 18b have the welding torch 5 of 0.1 mm or less in the X-direction, the Y-direction, and the Z-direction, respectively. The one that can be positioned with accuracy is used. The power cable of the Z-direction moving servo motor 11 and the control signal cable of the laser length measuring device 7 are coaxial with each other.
Is using. The rotating motor case 25 is provided with a cable winding device 27 that winds the coaxial cable 26.

The torch holder 6 includes a welding torch 5 in front of and behind the welding torch 5 so that the tungsten electrode 3 of the welding torch 5 is directed obliquely outward with respect to the central axis of rotation of the torch rotation shaft 8.
We support in some places. A long hole (not shown) is formed in one of the two supporting portions, and the welding torch 5 can swing about the one supporting portion.
That is, the welding torch 5 can change the angle with respect to the rotation center axis of the torch rotation shaft 8 within a certain range.

The welding torch 5 and the welding power source device 31 are connected by a coaxial main cable 28 in which a gas hose and a power cable are coaxial so that argon gas and welding power can be supplied from the welding power source device 31 to the welding torch 5. It is connected. The coaxial main cable 28 is connected to the welding torch 5 through a cable insertion hole (not shown) formed in the torch rotation shaft 8. The argon gas is sent from the gas cylinder to the welding power supply device 31, and the gas supply is adjusted there.

The welding wire feeding device 52 includes a wire reel 14 around which the welding wire 13 is wound.
And a welding wire feeder 12 that feeds the welding wire 13 from here to the vicinity of the tungsten electrode 3, and a wire that guides the welding wire 13 between the welding wire feeder 12 and the vicinity of the tungsten electrode. It is composed of the feeding guide 4. The wire reel 14 and the wire feeder 12 are fixed to the torch rotation shaft 8.

The laser length measuring device 7 is attached to the tip portion of the rotating shaft 8 in order to detect the distance to the boundary portion 23. The laser length measuring device 7 is attached to the rotating shaft 8 so that the measuring direction can be changed. The welding torch moving mechanism 50 is provided on the triaxial manipulator 22 via the fixing jig 21. Also, the camera 15
Is attached to the fixing jig 21 so that its imaging direction can be changed.

Next, the operation of the welding apparatus of this embodiment will be described with reference to the flow chart shown in FIG. First, the origin of each device is adjusted and various data are initialized (step 1). In step 1, first, the heat exchanger 60 is placed on the turning roll 61 so that the tube sheet 1 and the welding device face each other, and the horizontal and vertical levels of the tube sheet 1 are adjusted to about ± 10 mm / 2000 mm or less. adjust.

The origin of the three-axis manipulator 22 is adjusted. NC controller 3 for controlling the three-axis manipulator 22
The NC coordinate data for machining the pipe hole in the tube sheet 1 is used as the NC control coordinate data for No. 2. In this origin alignment, the tungsten electrode 3 is 30 ° to the central axis of the heat transfer tube 2.
After adjusting the orientation of the welding torch 5 so that the angle becomes about 70 °, the triaxial manipulator 22 is driven to move the welding torch 5 to the boundary portion 23 between the heat transfer tube 2 and the tube sheet 1 to be welded first. Then, the distance from the boundary portion 23 to the tip of the tungsten electrode 3 is about 0.5 to 1.5 mm, and the distance from the inner surface of the tube hole of the tube sheet 1 to the tip of the tungsten electrode 3 is 0.5 mm or less. Adjust manually so that

When the origin adjustment of the triaxial manipulator 22 is completed, the above-mentioned position of the tungsten electrode 3 with respect to the boundary portion 23 to be welded first is the boundary portion 2 to be welded second.
3 is the origin of the tungsten electrode 3. Specifically, based on the distance between the laser length measuring device 7 and the tube sheet 1,
Laser length measurement controller 37 and torch position controller 3
Perform 3 origin adjustment. In addition, as shown in FIG. 8, the distance Lp ₁ from the tube plate surface 36a of the first welded portion to the laser length measuring device 7 and the distance Lt ₁ from the pipe end face 35a to the laser length measuring device 7 are measured with a caliper or the like. This is set in the laser length measurement control device 37 and the torch position control device 33 as initial data. Further, the length measurement waiting time and the length measurement time of the laser length measurement are also initialized in the laser length measurement control device 37.

The focus of the camera 15 to the next welding position is manually adjusted. This camera 15 is a three-axis manipulator 22.
Since it is attached to the fixing jig 21 provided in
With the movement of the welding torch 5 in the pipe row direction by the shaft manipulator 22, the state of always facing the next welding position is maintained.

Next, the origin adjustment template is used to adjust the origin of the image data of the industrial camera 15 on the image processor 34 and the origin of the torch position controller 33. In the origin adjustment template, as shown in FIG.
Two reference holes 41b and 43b with the same diameter as the nominal tube hole diameter
Is drawn such that the distance between the center points 41a and 43a is the nominal pitch P. The plate for adjusting the origin is attached to the tube sheet 1 (the tube hole at the first welding portion and one reference hole 41b are aligned). Since the imaging direction of the camera 15 is adjusted so as to image the tube sheet 1 from a slightly oblique direction, for example, the actual tube hole pitch and the tube hole pitch obtained from the image data are different. Therefore, the image processing device 34 and the torch position control device 33 are adjusted so that the origin adjustment template attached to the tube sheet 1 is imaged and the tube hole pitch P obtained from the image data can be grasped as the nominal pitch. The center point 41 of the two reference circles 41b and 43b obtained from this image data
The coordinate values of a and 43a and the tube hole pitch P are initialized in the image processing device 34. Welding conditions such as welding current, welding speed, and welding wire feed amount are input to the welding control device 30.

In step 2, the welding start button is pressed to start the welding of the first boundary portion 23. Then, the welding control device 30 issues a command to the welding power source 31 to supply argon and welding current to the welding torch 5, and a wire feeding command to the wire feeder 12, and also a torch with a speed reducer. A control pulse signal relating to the timing and the rotation speed of the welding torch 5 starting to rotate is issued to the rotating stepping motor 16. As a result, the rotation motor 16 starts to drive, the welding torch 5 rotates about the rotation center axis of the rotation shaft 8, and TIG welding of the boundary portion 23 between the heat transfer tube 2 and the tube sheet 1 is started. At this time, since the tungsten electrode 3 faces obliquely outward with respect to the rotation center axis of the torch rotation shaft 8, the boundary portion 23 can be directly welded from the tube center side of the heat transfer tube 2, and the tube sheet 1 can be attached. It does not melt unnecessarily.

In step 3, in parallel with the start of step 2, the welding control device 30 transmits a length measurement control command to the laser length measurement control device 37, and the laser length measurement control device 3
7 outputs a length measurement start command to the laser length measuring device 7 after the preset length measurement waiting time has elapsed. Laser length measuring device 7
Rotates with the welding torch 5, and the laser beam emitted by the laser length-measuring device 7 forms a circular orbit 40 on the tube sheet 1 as shown in FIG. In the figure, 38 indicates the trajectory of the welding arc of the welding torch 5. When the laser length measuring device 7 rotates, the laser beam crosses the heat transfer tube 39 to be welded next. The laser length measurement device 7 performs length measurement until the laser length measurement controller 37 outputs a length measurement stop command after the initial setting of the length measurement time, and transmits the length measurement data to the laser length measurement control device 37. The laser measurement controller 37
The length measurement data is temporarily stored in the internal memory at a frequency of about every 0.1 seconds, and among the stored data, as shown in FIG.
Only the data of p ₁ ± 1.5 mm is extracted, these are averaged, and this average value is set as the distance Lp ₂ from the tube plate surface 36b of the second welded portion to the laser length measuring device 7. Further, of the stored data, only the data of Lt ₁ ± 1.5 mm is extracted, these are averaged, and this average value is used as the distance Lt from the pipe end surface 35 b of the second welded portion to the laser length measuring device 7.
_Set to ₂ . The laser length measurement controller 37 erases the distances Lp ₁ and Lt ₂ which are initial setting values from the internal memory, while
The calculated distances Lp ₂ and Lt ₂ are stored in the internal memory and are transmitted to the torch position control device 33.

The torch position control device 33 obtains the difference Dp ₁ between the distance Lp ₁ and the distance Lp ₂ which are initially set, and the difference Dp between the distance Lt ₁ and the distance Lt ₂ which is initially set.
t ₁ is obtained, and these values Dp ₁ and Dt ₁ are used as the position correction amounts in the Z direction of the welding torch 5 when welding the second welded portion. By the way, although the length measuring device itself does not need to use a laser, an optical length measuring device is preferable because distance measurement is performed in the vicinity of a high heat and high electromagnetic wave region.

In step 4, welding start information is transmitted from the welding control device 30 to the torch position control device 33 in parallel with the start of step 2. Upon receiving this, the torch position control device 33 outputs an imaging command to the image processing device 34, the camera 15 starts imaging centering on the second welding portion, and the image data is processed by the image processing device 34. Output to. By the way, as shown in FIG.
a is white due to the reflected light, the inside 44b of the tube is black, and the tube end surface 4
4c is imaged in gray. Therefore, the image processing device 34
Converts the image data into digital data and binarizes it into a data group showing a white portion and a data group showing a black portion. Further, the image processing device 34 obtains the center coordinates of the black portion from the coordinate values of the data group indicating the black portion. As shown in FIG. 5, the center coordinates are the coordinates of the center position 42a of the second welding portion, and thus the reference circle 43 that is initially set is set.
By comparing the coordinate value of the center position 43a of b with the coordinate value Dx of the two in the X direction and the difference Dy of the value in the Y direction, these values Dx and Dy are respectively calculated in the X direction and the Y direction.
The position correction amount of the welding torch 5 with respect to the direction is temporarily stored in the internal memory.

In step 5, when the welding torch 5 is rotated to the welding end position that has been initialized, the welding control device 30 outputs a supply end command of argon gas and welding current to the welding power source 31, and A rotation end command is output to the stepping motor 16 for rotating the torch with a speed reducer to end welding at the first welding position.

In step 7, the NC control device 32, which has received the welding completion information from the welding control device 30, outputs the coordinate data of the second welding portion of the NC coordinate data for pipe hole machining to the three-axis manipulator 22. To do. The three-axis manipulator 22 is driven to move the welding torch 5 to the second welding position. During this moving process, the welding torch 5
Is separated from the tube sheet 1 by a predetermined distance, the welding control device 30
Outputs a reversal command to the rotation motor 16. When the rotation motor 16 is driven and the torch rotation shaft 8 is reversed, the cable winding device 27 is driven.
This is because the Z-direction moving motor 11 and the laser length measuring device 7 rotate together with the rotation of the torch rotating shaft 8.
This is to prevent the coaxial cable 26 that sends electric power or a control signal to these from being loosened and caught when it is reversed.

In step 7, when the welding torch 5 is moved to the next welding position, in step 8, the tungsten electrode of the welding torch 5 is based on the position correction amount Dt ₁ of the welding torch 5 in the Z direction obtained in step 3. Correct the position of 3 in the Z direction. The position correction amount Dt ₁ in the Z direction is converted into the rotation amount of the Z direction moving motor 11 and output to the Z direction moving motor 11. When the Z-direction moving motor 11 is driven, the gear 9 rotates, the torch holder 6 moves in the Z direction while rotating, and the welding torch 5 moves for correction in the Z direction. As a result of this movement, the distance in the Z direction from the tip of the tungsten electrode 3 to the boundary portion 23 between the heat transfer tube 2 and the tube sheet 1 becomes 0.5 to 1.5 mm.

In step 9, the X-direction and Y-direction position correction amounts Dx and Dy of the welding torch 5 obtained in step 4 are obtained.
Based on, the position of the tungsten electrode 3 of the welding torch 5 in the X direction and the Y direction and the Z direction is corrected. The position correction amounts Dx and Dy in the X and Y directions are the rotation amount of the X direction moving motor 18a and the Y direction moving motor 1, respectively.
Converted to a rotation amount of 8b, the X-direction moving motor 18
It is output to the a and Y direction moving motor 18b. When the X-direction moving motor 18a and the Y-direction moving motor 18b are driven, the X-direction slide unit 19 and the Y-direction slide unit 20 move, and the welding torch 5 moves slightly in the X-direction and the Y-direction. As a result of this move,
The central axis of the heat transfer tube 2 and the central axis of rotation of the rotary shaft 8 coincide with each other. By this matching, the distance in the XY plane from the tip of the tungsten electrode 3 of the heat transfer tube 2 to the boundary portion 23 becomes 0.5 mm or less in all directions in the XY plane.

When the position correction of the welding torch 5 with respect to the second welded portion is completed, the processing from step 2 to step 9 is repeated again, and the heat transfer tube 2 is sequentially
And the tube sheet 1 are welded together. In this process, the position correction amount of the welding torch 5 with respect to the Nth welded portion is
It is calculated based on the data regarding the position of the (N-1) th welded portion. Further, the position correction amount of the welding torch 5 becomes 0 after the welding is completed (step 5) and while the manipulator 22 is being driven in step 7, and the position correction of the welding torch 5 with respect to the portion to be welded next is performed again. Done. That is, the welding torch moving mechanism 50 returns to the original position each time welding of each welded portion is completed, and thereafter,
The position of the welding torch 5 is corrected with respect to the portion to be welded next. Finally, when the welding of all the welded parts is completed (step 6), the welding torch moving mechanism 50, the manipulator 22 and the like are returned to the origin (step 10) and the process is completed.

As described above, in this embodiment, this NC data is corrected based not only on the NC data for pipe hole machining but also on the actually measured welding position (X, Y, Z directions). Therefore, the tungsten electrode 3 can be guided to the target position very accurately. Therefore, it is possible to improve the reliability of the welded portion, prevent the interference between the tungsten electrode 3 and the tube 2 and the tube sheet 1, and perform the continuous automatic welding operation of the tube 2 and the tube sheet 1. You can

Further, since the tungsten electrode 3 can be accurately guided to a target position without inserting the guide rod into the tube hole 24 as in the prior art, the portion where the guide rod existed, Place the welding torch 5,
Since the welding arc can be directed outward from the center side of the heat transfer tube 2, the boundary portion can be directly welded without chamfering the tube sheet 1. Therefore, as shown in FIG. 9, the welding apparatus of the present embodiment (shown by the solid line in the figure) has a much lower heat input than the conventional welding apparatus (shown by the two-dot broken line in the figure). As a result, it is possible to obtain a high-quality welded part with no defective penetration. For this reason, deterioration of mechanical properties and deterioration of corrosion resistance of the welded portion can be suppressed to a very small level. In addition, manual TIG welding (indicated by the dashed line in the figure)
The reason why welding is possible with lower heat input is that the positioning of the welding torch is accurate, the welding arc can be accurately guided to the target position, and efficient welding is possible. Further, the origin of the welding torch moving mechanism 50 is returned while the manipulator 22 is being driven, and the position of the next welded portion is measured during welding of a certain heat transfer tube. The heat pipe can be continuously welded, and the overall welding time can be shortened.

In the description of the operation of the welding apparatus of the present embodiment, only the heat transfer tube 2 drawn into the tube sheet 1 has been described, but the present welding apparatus uses the welding torch for the torch holder 6. It goes without saying that by changing the angle of 5, the heat transfer tube 2 can also be applied to a tube protruding from the surface of the tube sheet 1. Further, in the present embodiment, the position and the like of only the next welded portion are measured during welding of a certain heat transfer tube, but the positions and the like of several welded portions may be collectively measured.

[0040]

According to the present invention, the position of the welding torch is actually measured by using the image pickup means or the like to correct the position of the welding torch. Can be guided accurately. In addition, the welding arc can be directed outward from the central axis of the pipe, and even if the tip of the pipe is pulled into the tube sheet, it is possible to weld the boundary portion directly without chamfering the tube sheet. Therefore, welding with excellent mechanical properties and corrosion resistance can be performed without spending man-hours.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a welding device according to an embodiment of the present invention.

FIG. 2 is an overall front view of a welding apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a welding apparatus according to an embodiment of the present invention.

FIG. 4 is a flowchart showing an operation sequence of the welding apparatus according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining a correction amount of a tube hole center position according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an image of a tube sheet taken by a camera of one embodiment according to the present invention.

FIG. 7 is an explanatory diagram showing a locus of a laser beam of a laser length measuring machine according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a positional relationship between a laser length measuring device and a tube sheet according to an embodiment of the present invention.

FIG. 9 is a graph showing the relationship between the wall thickness of the heat transfer tube and the heat input amount for each welding method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tube plate, 2 ... Tube, 3 ... Tungsten electrode, 5 ... TIG welding torch, 6 ... Torch holder, 7 ... Laser length measuring machine, 8
... torch rotary shaft, 11 ... torch Z-direction movement servomotor, 12 ... welding wire feeder, 13 ... welding wire, 14 ... welding wire reel, 15 ... small camera, 1
6 ... Stepping motor for torch rotation with reduction gear, 1
8a ... X-direction moving servo motor, 18b ... Y-direction moving servo motor, 19 ... X-direction slide unit, 20
... Y direction slide unit, 21 ... Fixing jig, 22 ... 3
Axis manipulator, 23 ... Boundary part, 24 ... Tube hole, 25 ...
Torch rotation motor case, 26 ... coaxial cable, 2
7 ... Cable winding device 28 ... Coaxial main cable,
30 ... Welding control device, 31 ... Welding power supply, 32 ... NC control device, 33 ... Welding torch position control device, 34 ... Image processing device, 50 ... Torch moving mechanism, 52 ... Welding wire feeding device, 60 ... Heat exchange vessel.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Ishikawa 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Norio Kitamura 3-chome, Saiwaicho, Hitachi-shi, Ibaraki No. 1 Inside Hitachi Works, Hitachi Works (72) Inventor Akio Manago 3-1-1, Saiwaicho, Hitachi City, Ibaraki Hitachi Works Hitachi Works, Hitachi Works

Claims (4)

[Claims] 1. A welding device for welding a plurality of pipes respectively inserted into a plurality of pipe holes of a pipe sheet to the pipe sheet, a welding torch for welding an annular boundary portion between the pipe and the pipe sheet, The welding torch is mounted such that it can redirect the welding arc with respect to the boundary to move the welding torch relative to the tube sheet, and the welding arc of the welding torch to the annular boundary. Welding torch moving means for rotating the welding torch so as to move along, imaging means for imaging the tube sheet, and the position of the tube hole on the tube sheet from the image obtained by the imaging means. The image processing means to be obtained, the length measuring means for measuring the distance to the boundary portion, and the welding torch is sequentially guided to the vicinity of the plurality of pipe holes based on the position data of the plurality of pipe holes obtained in advance. To be taken Welding of the welding torch based on the position of the tube hole obtained by the image processing means and the distance to the boundary obtained by the length measuring means while controlling the driving amount of the welding torch moving means. A welding torch position control device that outputs a correction amount to the welding torch moving means to the welding torch moving means so that the arc is directed to the boundary portion and the distance from the tip of the welding torch to the boundary portion becomes a predetermined distance. A welding device comprising: 2. The welding torch moving means includes a coarse welding torch moving mechanism for sequentially guiding the welding torch to the vicinity of the plurality of pipe holes based on the position data of the plurality of pipe holes obtained in advance. The welding torch is mounted so as to change the direction of its welding arc with respect to the boundary, the welding arc of the welding torch is directed to the boundary based on the correction amount, and the tip of the welding torch is located at the boundary. A welding torch correction moving mechanism for correcting and moving the welding torch so that the welding torch is separated by the predetermined distance, and rotating the welding torch so that the welding arc of the welding torch moves along the boundary portion. The welding device according to claim 1, wherein the welding device is a welding device. 3. The length measuring means is an optical length measuring device, and is attached to the welding torch moving means so as to change its measuring direction and rotate with the rotation of the welding torch. The welding device according to claim 1 or 2, which is characterized. 4. While the welding torch is rotating, the imaging means images the boundary portion to be welded next, and the length measuring means can measure the distance to the boundary portion to be welded next. 3. The welding apparatus according to claim 1, wherein the image pickup means and the length measuring means are attached to the welding torch moving means.