JP2862255B2 - Laser welding equipment for pipe inner peripheral surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thin tube such as a heat transfer tube of a heat exchanger and a repair sleeve inserted into the thin tube so as to cover a damaged portion generated in the thin tube from the inside. The present invention relates to a welding device for performing circumferential seal welding.

<Conventional technology> In steam motors and various power plants that directly use thermal energy, boilers and their associated heaters, feedwater preheaters, air preheaters, condensers, etc., play a major role. As a matter of course, in various chemical industries such as petrochemical and petroleum industries, a heat exchange device or a heat exchanger is frequently used in each process. In particular, a general multi-tube cylindrical type heat exchanger is widely used as a large-sized heat exchanger, and is sufficiently usable in the high-temperature and high-pressure equipment industry.

Meanwhile, a steam generator that generates steam for rotating turbine blades is known as one of the most important incidental facilities in a power reactor. In general, a steam generator used in a pressurized water reactor is a type of a multi-tube cylindrical heat exchanger that vaporizes secondary water by heat exchange with primary water heated in the reactor. The schematic internal structure of such a steam generator is, as shown in FIG. 16, a water chamber 3 in which a lower end of a vertical cylindrical shell 1 is partitioned by a horizontal tube sheet 2 to form a hemisphere. Furthermore, end portions of a large number of U-shaped steam thin tubes 5 are divided into two by vertical partition walls (not shown) and penetrate through the tube sheet 2 to be open to these two water chambers 3 respectively. These steam tubes 5 are supported in the cylindrical shell 1 via a plurality of support plates 6. High-temperature primary-side water from a reactor (not shown) enters through an inlet nozzle 7 communicating with one of the water chambers 3, reaches the other water chamber 3 through the steam capillary 5, and an outlet (not shown) communicating with the water chamber 3. While returning to the reactor through the nozzle, the secondary side for turbine operation supplied to the inside of the cylindrical shell 1 from a water supply nozzle (not shown) provided on the side surface of the cylindrical shell 1 while passing through these steam tubes 5. Heat exchange with water.
The secondary-side water that has become high-temperature steam in this way is sent from above the cylindrical shell 1 to a steam turbine (not shown).

Normally, in nuclear facilities, the materials used are carefully selected, and their quality control is also very strict. In the above-mentioned steam generator, various inspections and repairs are performed periodically during its operation.
If one of the steam tubes is abnormal, the following service exclusion process is performed. That is, in order to prevent high-pressure primary water from leaking out of the steam capillary, blind ends are filled at both ends of the steam capillary and seal welding is performed around the blind cap to close the steam capillary.

<Problems to be Solved by the Invention> In a multi-tube cylindrical heat exchanger, in a method in which a damaged heat transfer tube is closed with a blind plug, as the number of damaged heat transfer tubes increases, the heat exchanger becomes a heat exchanger. There is a possibility that the function is significantly reduced and the efficiency of the entire plant is also deteriorated. For this reason, if the number of damaged tubes is expected to be large, insert the repair sleeve into the heat transfer tube so that the damaged portion is covered instead of the blind plug, and attach both ends of this repair sleeve to the heat transfer tube. The circumference seal is welded.

However, in this method, if the material of the heat transfer tube is special, it is necessary to use a considerable high-temperature brazing material, so that the metallurgical structure of the heat transfer tube and repair may be changed in addition to the difficulty in construction. Many. Furthermore, a long repair sleeve could not be inserted into the heat transfer tube depending on the size of the water chamber for repair work. Therefore, instead of such welding, a method of forming an annular projection on the outer peripheral surface of the repair sleeve, expanding the annular projection, and causing the projection to bite into the inner peripheral surface of the heat transfer tube to maintain airtightness may be considered. ing. However, if the heat transfer has already been expanded by this method, the portion of the heat transfer tube is work-hardened, so the protrusion of the repair sleeve needs to bite into the inner peripheral surface of the heat transfer tube. The material must be sufficiently harder than the material of the heat transfer tube, and there are various restrictions.

The present invention solves such a problem,
It is an object of the present invention to provide a pipe inner peripheral surface laser welding apparatus which improves workability of a work pipe repair work.

<Means for Solving the Problems> In order to achieve the above-described object, a laser welding apparatus for an inner peripheral surface of a pipe according to the present invention has a flexible structure in which an optical fiber for transmitting a laser beam for welding is inserted and a distal end is inserted into a working pipe. A tube, a position detector provided at a distal end portion of the flexible tube to detect a relative position of the flexible tube with respect to the working tube, and an inwardly expanding fixing means for fixing the flexible tube in the working tube; A rotary tube rotatably supported by a flexible tube, and guide support means mounted rotatably relative to the rotary tube and abutting against the inner wall of the working tube to hold the rotary tube concentrically with the working tube A rotation driving means having an output shaft arranged coaxially with the rotary cylinder and driving the rotary cylinder to rotate; and an optical filter provided in the rotary cylinder and A converging / reflecting optical system having a plurality of lenses and a reflecting mirror that guides the welding laser beam emitted from the tip of the rod to the inner wall of the working tube in a condensed state, and a base end provided in the rotating cylinder. A gas supply path connected to an external gas supply source and having a distal end connected to the gas distribution section, and an injection nozzle having one end connected to the distribution section of the gas supply path and the other end directed to the condensing / reflecting optical system Scavenging means having a scavenging gas passage communicating with the scavenging gas passage for removing metal vapor generated at the time of welding of the working pipe; Lens cooling means having a first cooling gas passage connected to a portion and having the other end communicating with the plurality of lenses of the converging / reflecting optical system; and the scavenging gas passage and the first
A reflecting mirror cooling means having a second cooling gas passage provided alongside the cooling gas passage and having one end connected to the distribution section of the gas supply passage and the other end communicating with the reflecting mirror of the converging / reflecting optical system. It is characterized by having.

<Operation> The flexible tube inserted into the working tube is stopped at a predetermined working location by the position detector, and the flexible tube is fixed to the working tube by the fixing means.
At this time, the rotary cylinder is held concentrically with respect to the working tube by the guide support means, and from this state, the welding laser beam is irradiated on the inner wall of the working pipe via the converging / reflecting optical system, and at the same time, the rotating drive means is used. The rotating cylinder is rotated, and the laser beam for welding is caused to scan annularly with respect to the inner wall of the working tube.

The scavenging means distributes the gas flowing from the gas supply source to the gas supply path to the scavenging gas path via the distribution unit,
The scavenging gas supplied from the scavenging gas passage is removed from the metal nozzles generated during the welding operation by injecting the scavenging gas from the injection nozzle, and the lens cooling means is circulated from the gas supply source to the gas supply passage. The cooled gas is distributed to the first cooling gas passage via the distribution unit, and is cooled by supplying the cooling gas supplied from the first cooling gas passage to the plurality of lenses of the condensing and reflecting optical system. Further, the reflecting mirror cooling means distributes the gas flowing from the gas supply source to the gas supply path to the second cooling gas passage via the distribution unit, and performs second cooling on the reflecting mirror of the condensing reflection optical system. By supplying the cooling gas supplied from the gas passage, the cooling gas is cooled, and the welding operation efficiency is improved.

<Embodiment> Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a laser welding apparatus for an inner peripheral surface of a pipe according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is a sectional view taken along line III-III of FIG. 4 is a sectional view taken along line IV-IV of FIG. 1, FIG. 5 is a sectional view taken along line VV of FIG. 1, FIG. 6 is a sectional view taken along line VI-VI of FIG. 1, and FIG. VII-VII sectional view, FIG. 8 is a VIII-VIII sectional view of FIG. 1, and FIG. 9 is an IX of FIG.
FIG. 10 is a sectional view taken along line XX of FIG. 1, FIG. 11 is a sectional view taken along line XI-XI of FIG. 1, FIG. 12 is a sectional view taken along line XII-XII of FIG. Is a sectional view taken along the line XIII-XIII in FIG. 1, and FIG.
FIG. 15 is a sectional view taken along the line XIV-XIV of FIG. 15, and FIG.

As shown in FIG. 1, a connecting tube 14 having an eddy current type position detector 13 mounted on the outer peripheral surface thereof in the present embodiment is attached to a distal end of a flexible tube 12 whose distal end is inserted into the heat transfer tube 11. 15 are integrally fitted. The position detector 13
Is a tube plate, support plate, or heat transfer tube 11 (not shown) of the heat exchanger.
The position of the repair sleeve 17 inserted and positioned in the heat transfer tube 11 so as to cover the defective portion 35 and the vicinity thereof is detected, and the heat transfer tube 11 and the repair sleeve 17 are welded with a YAG laser or a carbon dioxide gas laser, which will be described later. This is for setting the irradiation position of the laser beam 18, and other than the eddy current type can naturally be adopted.

At the tip of the connection cylinder 14, an intermediate cylinder 20 covered with an airbag 19 as a fixing means formed of a synthetic rubber or the like having a suitable strength and elasticity is integrally fitted,
The intermediate cylinder 20 has a supply opening (not shown) for opening the outer peripheral surface of the intermediate cylinder 20 and supplying compressed air between the outer peripheral surface of the intermediate cylinder 20 and the inner peripheral surface of the cylindrical airbag 19. An exhaust hole is formed. An air supply / exhaust device (not shown) is connected to the air supply / exhaust hole through the connection tube 14 and the flexible tube 12, and the compressed air is supplied from the air supply / exhaust hole into the airbag 19 by the air supply / exhaust device. Then the airbag
19 expands and comes into close contact with the inner wall of the heat transfer tube 11 so that the distal end side of the device is fixed to the heat transfer tube 11. In addition,
Other gas or liquid may be used in place of the compressed air, and other well-known inward expansion type fixing means may be used instead of the airbag 19 of the present embodiment. Further, the connecting tube 14 and the intermediate tube 20 for the flexible tube 12 are provided.
May be reversed.

At the end of the intermediate cylinder 20, a fixed cylinder 24 that houses a drive motor 23 as a rotation driving means is integrally fitted,
A rotary cylinder 26 as an output shaft of the drive motor 23 is rotatably supported inside the fixed cylinder 24 via a bearing 25, and a support cylinder 27 is integrally fitted to a distal end thereof. As the drive motor 23, for example, a stepping motor, an ultrasonic motor, or the like is used as a short type, low rotation, high torque type motor.

Inside the rotary cylinder 24, as shown in FIGS. 11 and 12, scavenging and gas passages 61, 62, 63 constituting a cooling means described later through a sleeve 28 are formed in a fiber in a longitudinal direction. The sheath 29 is fixed. Outside the fiber sheath 29 and the sleeve 28 and below the drive motor 23, the intermediate cylinder 20, the fixed cylinder 24, the rotating cylinder 26 with respect to the support cylinder 27,
A pulse encoder 30 for controlling the amount of rotation of the sleeve 28 and the fiber sheath 29 is provided. Therefore, the pulse encoder 30 can transmit the detection signal to control means such as a microcomputer (not shown) to control the drive motor 23.

A cable (not shown) connected to the drive motor 23 and the pulse encoder 30 is connected to a control device (not shown) through the intermediate tube 20, the connection tube 14, and the flexible tube 12. It is connected to a laser launcher and the like, which will be described later, in addition to the air supply / exhaust device, and issues control commands necessary for these.

An optical fiber that passes through the support tube 27, the fixed tube 24, the intermediate tube 20, the connection tube 14, and the flexible tube 12 and is connected to a laser oscillator (not shown) inside the fiber sheath 29.
33 is inserted, and at the center of the distal end of the fiber sheath 29, the distal end 34 of the optical fiber 33 is fixed. In front of the emission end face (tip) 34 of the optical fiber 33 transmitting the welding laser beam 18 from the laser oscillator, a welding laser beam emitted in a diffused state from the emission end face 34 of the optical fiber 33 is provided. 18 heat transfer tube 11 and repair sleeve
A converging optical system 36 that converges toward a weld 35 with 17 is provided.

That is, a cylindrical lens case 41 is fixed to the upper part of the rotary cylinder 26, and a plurality of lenses 40 are mounted inside the lens case 41 in a vertical direction. Also, the support cylinder 27
While a female screw 42 is formed on the upper inner periphery of the mirror case 43, a mirror case 43 is located above the support cylinder 27, and a male screw 44 is formed on the lower outer periphery of the mirror case 43, and they are screwed together. An engaging pin 45 is fixed to the side of the mirror case 43, while an elongated hole 46 is formed along the vertical direction on the side of the lens case 41, and the engaging pin 45 is inserted into the elongated hole 46. It is slidably fitted. Support shaft on top of mirror case 43
47 is fixed, and a reflecting mirror 49 is attached to the lower surface of the support shaft 47 via a base 48. The reflecting mirror 49 introduces the welding laser beam 18 into the welding portion 35 of the repair sleeve 17 and is fixed at an angle of 45 ° with respect to the rotation axis of the rotating cylinder 26. Then, as shown in FIG.
A fin 50 for radiating heat received when reflecting the laser beam 18 is attached to an outer peripheral portion of the pedestal 48. A beam irradiation hole 51 through which the laser beam 18 passes is formed on one side of the mirror case 43, and a tungsten plate 52 having a melting point of about 3500 ° C. is fixed to the beam irradiation hole 51.

Accordingly, when the lens case 41 is rotated by the drive motor 23 via the rotary cylinder 26, the mirror case 43 is rotated via the engagement pin 45, and the support cylinder 27 is screwed by the screwing relationship between the support cylinder 27 and the mirror case 43. The mirror case 43 moves upward or downward with respect to the lens case 41, and the reflecting mirror 46 performs welding while performing a screwing motion.

Guide support means for holding the rotating cylinder 26 concentrically with the heat transfer tube 11 is provided on the upper part of the mirror case 49. As shown in FIGS. 1 and 3, a roller support sleeve 54 is rotatably supported on the upper portion of the support shaft 47 via a bush 53, as shown in FIGS. A pair of annular sliders 55 are slidably fitted to the roller support sleeve. A pair of links 57 for rotatably supporting a roller 56 abutting on the inner wall of the heat transfer tube 11 is pinned to each of the sliders 55. The rollers 56 and the links 57 are equally spaced around the roller support sleeve 54. A plurality of sets (three sets in this embodiment) are provided. A compression spring 58 is interposed between both ends of the roller support sleeve 54 and the slider 55, and the roller 56 is automatically moved to the inner wall side of the heat transfer tube 11 through the ring 57 by the spring force of the compression spring 58. The rotary cylinder 26 is held concentrically with the heat transfer tube 11. It is to be noted that any guide supporting means other than this embodiment may be used as long as it can hold the rotary cylinder 26 concentrically with the heat transfer tube 11. Further, a large number of exhaust gas holes 59 are formed in the upper portion of the roller support sleeve 54, as shown in FIG.

In addition, the pipe inner peripheral surface laser welding apparatus is provided with scavenging means for removing metal vapor or the like generated when the repair sleeve 18 is welded, and cooling means for cooling the converging / reflecting optical system 36. As shown in FIG. 10, a gas passage (scavenging gas passage) 61 for removing metal vapor generated during welding, a cooling gas passage (first cooling gas passage) 62 for the lens 40, and a fiber sheath 29 are provided in the fiber sheath 29. A cooling gas passage (second cooling gas passage) 63 for the reflecting mirror 40 is formed. And each of these gas passages 6
The base ends of 1, 62 and 63 are connected to a gas supply source (not shown) through a single gas flow path via a distributor.

As shown in FIGS. 1 and 6 to 10, a gas passage 61 for removing metal vapor communicates with a gas passage 64 formed in the lens case 41, and is attached to the upper end of the lens case 41. It communicates with the injection port 65. Accordingly, an inert gas such as He (helium), Ne (neon), or N ₂ (nitrogen) passes from the injection nozzle 65 through the beam irradiation hole 51 to the reflecting mirror 49.
It will be injected toward.

The cooling gas passage 62 of the lens 40 opens around the exit end face 34 of the optical fiber 33 to cool each lens 40. The cooling gas passage 63 of the reflecting mirror 49 communicates with a gas passage 66 formed in the lens case 41, and further communicates with an injection nozzle 67 attached to the upper end of the lens case 41. Therefore, the cooling gas is cooled by being injected from the injection nozzle 67 toward the fin 50 mounted on the base 48 of the reflecting mirror 49.

These various gases are discharged to the outside through gas discharge holes 68 formed in the upper part of the mirror case 43, as shown in FIG.

Hereinafter, the repair operation of the heat transfer tube 11 by the repair sleeve 17 in the laser welding apparatus for the inner peripheral surface of the pipe of the present embodiment thus configured will be described.

As shown in FIG. 15, the laser welding device of the present embodiment is inserted into the heat transfer tube 11 in which the repair sleeve 17 is fitted in advance from the distal end, and the position detector 13 welds the beam irradiation hole 51 to the beam irradiation hole 51. Positioning is performed so that the location 35 is opposed. afterwards,
Compressed air is supplied into the airbag 19 to transfer the intermediate cylinder 20 to the heat transfer tube.
Fix to 11. At this time, the rotary cylinder 26 is held concentrically with the heat transfer tube 11 by the guide support means roller 56.

Then, the drive motor 23 is operated to rotate the rotary cylinder 26 and irradiate the welding laser beam 18 to the welding location 35 to perform circumferential seal welding between the heat transfer tube 11 and the repair sleeve 17.
That is, when the rotating cylinder 26 rotates, the lens case 41 rotates, and the mirror case 43 rotates via the engagement pin 45. Then, while the reflecting mirror 49 of the mirror case 43 is rotated with respect to the support cylinder 27 and the lens case 41 by the screwing relationship between the support cylinder 27 and the mirror case 43, the reflecting mirror 49 is actually several mm upward by the stroke of the long hole 46. The reflector 49 performs a welding operation by irradiating the inner peripheral surface of the repair sleeve 17 while performing a screw motion.

At this time, the inert gas supplied from the gas supply source to the gas flow path in the connection tube 14 passes through the distribution section to each of the gas passages 61, 62,
A predetermined amount is distributed and supplied to 63. Then, the inert gas distributed to the gas passage 61 is injected as a scavenging gas from the injection nozzle 65 through the gas passage 64 toward the converging / reflecting optical system 36 such as the reflecting mirror 46 and the lens 40. As a result, the metal vapor generated during welding is removed, and the welding laser beam is removed.
The damage caused by 18 has been prevented.

In addition, the inert gas distributed to the cooling gas passages 62 and 63 in the distribution section is injected from the vicinity of the exit end face portion 34 of the optical fiber 33 as a lens cooling gas and a reflector cooling gas to cool each lens 40. At the same time, the gas is injected from the injection nozzle 67 through the gas passage 66 toward the fin 50 on the outer periphery of the pedestal 48 of the reflector 49 to cool the reflector 40.

Therefore, the converging / reflecting optical system 36 can guide the welding laser beam 18 emitted from the optical fiber 33 to the inner wall of the heat transfer tube 11 in an appropriate converging state.

Each of the injected gases is discharged to the outside through the gas discharge holes 68 on the upper part of the mirror case 43.

<Effects of the Invention> As described above in detail with the embodiments, according to the laser welding apparatus for the inner peripheral surface of the pipe, the laser beam is used for the inner peripheral seal welding between the working pipe and the repair sleeve, and the laser beam is used. The scavenging means and cooling means, each having a gas passage for scavenging and cooling the condensing and reflecting optical system, are provided independently, enabling good seal welding without being affected by the material of the repair sleeve and working pipe In addition, the work of positioning the welding portion and setting the repair sleeve can be greatly simplified. Further, the scavenging and reflecting optical system can be easily and reliably cooled and welded during the welding work with a simple structure without increasing the size of the apparatus, so that a good laser beam focusing state is always maintained. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a laser welding apparatus for an inner peripheral surface of a pipe according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of FIG. 1, FIG. 3 is a cross-sectional view of FIG. 1 is a sectional view taken along line IV-IV of FIG. 1, FIG. 5 is a sectional view taken along line VV of FIG. 1, and FIG. 6 is a sectional view taken along line VI-VI of FIG.
FIG. 7 is a sectional view taken along the line VII-VII of FIG. 1, FIG. 8 is a sectional view taken along the line VIII-VIII of FIG. 1, FIG. 9 is a sectional view taken along the line IX-IX of FIG. 1 is a sectional view taken along line XX of FIG. 1, and FIG. 11 is a sectional view of FIG.
FIG. 12 is a sectional view taken along the line XII-XII of FIG. 1, and FIG.
FIG. 14 is a sectional view taken along the line XIII-XIII of FIG. 1, and FIG. 14 is a sectional view taken along the line XIV of FIG.
-XIV sectional view, Fig. 15 is an explanatory view of a mounting state of the laser welding device on the inner peripheral surface of the pipe, and Fig. 16 is a partially cutaway perspective view of a general steam generator. In the drawing, 11 is a heat transfer tube, 12 is a flexible tube, 13 is a position detector, 17 is a repair sleeve, 18 is a laser beam, 19 is an air bag (fixing means), 23 is a driving motor (rotation driving means), 26 is Rotating cylinder (output shaft), 30 is a pulse encoder, 33 is an optical fiber, 35 is a welding point, 36 is a condensing and reflecting optical system, 40 is a lens, 49 is a reflecting mirror, 61, 62, 63 are gas passages, 65, 67 is an injection nozzle.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nagashima, 1-1 1-1 Wadazakicho, Hyogo-ku, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. 1-1 1-1 Tazakicho Inside Kobe Shipyard, Mitsubishi Heavy Industries, Ltd. (56) References JP-A 64-27788 (JP, A) JP-A 64-27789 (JP, A) (58) Fields investigated (Int .Cl. ⁶ , DB name) B23K 26/00

Claims (1)

(57) [Claims] 1. A flexible tube through which an optical fiber for transmitting a laser beam for welding is inserted and a distal end side of which is inserted into a working tube, and a flexible tube provided at a distal end portion of the flexible tube, respectively, relative to the working tube. A position detector for detecting a position and an inwardly expanding fixing means for fixing the flexible tube in the working tube; a rotating cylinder rotatably supported by the flexible tube; and a rotatable relative to the rotating cylinder. Guide support means mounted and abutting on the inner wall of the working tube to hold the rotating tube concentrically with the working tube; and a rotation having an output shaft disposed coaxially with the rotating tube and driving the rotating tube to rotate. Driving means for guiding the welding laser beam, which is provided in the rotary cylinder and is emitted from the tip of the optical fiber, to the inner wall of the working tube in a condensed state; A condensing / reflecting optical system having a plurality of lenses and a reflecting mirror; and a gas supply path provided in the rotating cylinder, a base end of which is connected to an external gas supply source and a tip end of which is connected to a gas distribution unit. A scavenging gas passage having one end connected to the distribution portion of the gas supply path and the other end communicating with the injection nozzle to the light-collecting / reflecting optical system to remove metal vapor generated during welding of the working pipe. Scavenging means, a first provided in the rotary cylinder alongside the scavenging gas passage, one end of which is connected to a distribution portion of the gas supply passage, and the other end of which is in communication with the plurality of lenses of the condensing and reflecting optical system. A lens cooling means having a cooling gas passage; a scavenging gas passage in the rotary cylinder;
A reflecting mirror cooling means having a second cooling gas passage provided alongside the cooling gas passage and having one end connected to the distribution section of the gas supply passage and the other end communicating with the reflecting mirror of the converging / reflecting optical system. An inner peripheral surface laser welding apparatus characterized by comprising: