CN115773420A - Composite welding plug and plugging method - Google Patents

Abstract

The invention provides a composite welding plug and a plugging method, relates to the technical field of pipeline plugging, and aims to solve the problems of insufficient welding depth and low bonding strength of the existing welding pipe plugging mode. The composite welding plug comprises a plug body and a brazing filler metal layer arranged around the circumference of the plug body, wherein the plug body comprises a plugging section, a thread section and a boss section which are sequentially arranged along the axial direction of the plug body; the thread section is provided with external threads matched with the internal threads of the heat transfer pipe, and the small diameter of the thread section is larger than the maximum diameter of the plugging section; the outer diameter of the boss section is not smaller than the small diameter of the internal thread of the heat transfer pipe, and the end face, close to the thread section, of the boss section is used for being abutted to the bottom end of the heat transfer pipe. The invention ensures the welding depth and improves the bonding strength.

Description

Composite welding plug and plugging method

Technical Field

The invention relates to the technical field of pipeline plugging, in particular to a composite welding plug and a plugging method.

Background

The steam generator is one of the most critical devices in the high temperature gas cooled reactor nuclear power system, wherein the corrosion damage of the steam generator water supply end heat transfer pipe is always the main factor of the unplanned shutdown of the nuclear power plant and the loss of the capacity factor of the power plant. The steam generator feed side heat transfer tubes are an important component of the primary circuit pressure boundary and are important barriers against leakage of radioactive fission products, the total area of which accounts for 80% of the primary circuit coolant system pressure boundary. In the service process, the heat transfer pipe at the water supply end can be mechanically or chemically damaged under the washing of high-temperature, high-pressure and high-radiation dose medium for a long time, so that the heat transfer pipe at the water supply end is damaged, radioactive coolant leaks, and serious bad social feedback and huge economic loss are caused. The steam generator water supply end heat transfer pipe is the weakest link in a loop pressure-bearing boundary, the quality degradation of the water supply end heat transfer pipe cannot be completely avoided by the existing design, and according to statistics, nearly half of the steam generators of the nuclear power stations in the world operate with damage.

When the quality of the heat transfer pipe at the water supply end is seriously degraded, a pipe blocking mode is usually adopted to prevent the secondary side fluid from being polluted by radiation.

Common pipe plugging techniques include explosive plugging, welded plugging, and mechanical plugging. Wherein, explosion plugging pipes are easy to cause stress corrosion due to high residual stress and are basically not used any more; the mechanical pipe plugging process is simple, the time required by pipe plugging is short, and the mechanical pipe plugging process is widely applied to in-service pipe plugging service at present, but the structure of the plug is complex; although the welding pipe plug is widely used, the problems of insufficient welding depth and low bonding strength exist in the using process.

Disclosure of Invention

The invention aims to provide a composite welding plug, which aims to solve the technical problems of insufficient welding depth and low bonding strength of the existing welding pipe plugging mode.

The invention provides a composite welding plug, which comprises a plug body and a brazing filler metal layer arranged around the circumference of the plug body, wherein the plug body comprises a plugging section, a thread section and a boss section which are sequentially arranged along the axial direction of the plug body; the thread section is provided with an external thread matched with an internal thread of the heat transfer pipe, the small diameter of the thread section is larger than the maximum diameter of the plugging section, and the thread section is at least provided with a first position which is partially screwed into the heat transfer pipe and a second position which is fully screwed into the heat transfer pipe; the outer diameter of the boss section is not smaller than the small diameter of the internal thread of the heat transfer pipe, and the end face, close to the thread section, of the boss section is used for being abutted to the bottom end of the heat transfer pipe.

Further, the plug body further comprises a circular table section, the circular table section is provided with a small end face and a large end face which are arranged in an opposite mode, the large end face is fixedly connected with the plugging section, and the outer diameter of the large end face is smaller than the small diameter of the internal thread of the heat transfer pipe; the small end face is used for guiding the plug body to be installed into the heat transfer pipe.

Furthermore, the blind hole penetrates through the blocking section, and the closed end of the blind hole is formed by the large end face.

Furthermore, along the radial direction of the plug body, an annular step surface is formed at the part of the thread section, protruding out of the plugging section, and the end face, close to the thread section, of the brazing filler metal layer is abutted to the annular step surface.

Further, the ring width of the annular step surface is not less than 1.5mm.

The material of the plug body is the same as that of the heat transfer pipe.

Further, along the axial direction of the plug body, the size of the plugging section is not smaller than three screw pitches of the internal thread of the heat transfer pipe; and/or the size of the thread section is not smaller than four thread pitches of the internal thread of the heat transfer pipe along the axial direction of the plug body; and/or the size of the boss section is not more than 3mm along the axial direction of the plug body.

Further, the minimum wall thickness of the plugging section is not less than 1.5mm.

The invention has the beneficial effects brought by the composite welding of the plugs:

through setting up the hybrid welding end cap mainly comprising end cap body and brazing filler metal layer, wherein, the end cap body includes shutoff section, screw thread section and the boss section that sets gradually along its axial, and the brazing filler metal layer encircles the circumference that sets up in the shutoff section, and the blind hole of intercommunication boss section, screw thread section and shutoff section is seted up to the boss section. When needs carry out the shutoff to the heat-transfer pipe of feedwater end, because the heat-transfer pipe of feedwater end is in and erects the state of putting, so the end cap body will be followed supreme installation from the lower and gone into the heat-transfer pipe, and specific installation process is: the plug body is in spiral fit with the internal thread of the heat transfer pipe through the threaded section of the plug body, so that the plug body is positioned at a first position where the threaded section is partially screwed into the heat transfer pipe; then, continuously heating the inner surface of the groove of the plug by using a cleaver, transferring heat to the brazing filler metal through the plug, melting the brazing filler metal, and allowing the liquid brazing filler metal to flow downwards under the action of gravity and enter a space between the plug body and the heat transfer pipe; and after the brazing filler metal is completely melted, the robot controls the riving knife to continuously rotate the plug body so that the plug body is positioned at a second position where the thread section is completely screwed into the heat transfer pipe, at the moment, the boss section plays a role in positioning the plug body, and when the riving knife rotates to drive the plug to rotate so that a certain pretightening force is formed between the boss section and the bottom end of the heat transfer pipe, the rotation is stopped. And then, positioning a TIG (Tungsten Inert Gas Welding) head, enabling the TIG head to heat the part of the boss section, which is contacted with the bottom end of the heat transfer pipe, along the circumferential direction of the heat transfer pipe, melting the bottom of the heat exchange pipe, the part of the boss section, which is contacted with the bottom end of the heat transfer pipe, and the part of the thread section, which is close to the boss section, and further sealing the plug body and the heat transfer pipe after the materials of the parts are melted, thereby achieving the purpose of plugging the heat transfer pipe.

The arrangement form of the composite welding plug can continuously supplement brazing filler metal during thread brazing, and effectively improves welding quality.

In addition, mechanical heat pulse chopper brazing combines together with TIG welding, has increased the connection point position and the welding seam distribution region of end cap body and heat-transfer pipe, still promoted the joint strength of end cap body and heat-transfer pipe when guaranteeing to weld deeply, moreover, in can also getting into the thread clearance between shutoff body and the heat-transfer pipe after the brazing filler metal melts, realized the fixed connection of this position department internal thread and external screw thread, prevent that the end cap body is not hard up, the stifled pipe leakproofness is good, the reliability is high, longe-lived. In addition, when carrying out the assembly of end cap body and heat-transfer pipe, can utilize the cooperation of robot and blind hole, send the end cap body into the heat-transfer pipe, realized remote automatic stifled pipe, avoid the staff to receive nuclear radiation, the safety in utilization is high, is convenient for carry out quick stifled pipe operation to steam generator feedwater end heat-transfer pipe.

The second purpose of the invention is to provide a plugging method, which aims to solve the technical problems of insufficient welding depth and low bonding strength of the existing welding pipe plugging mode.

The invention provides a plugging method for plugging a heat transfer pipe at a water supply end by using the composite welding plug, which comprises the following steps: the robot grabs the plug, so that the riving knife is matched with the blind hole for positioning, the plug body is in spiral fit with internal threads of the heat transfer pipe through a threaded section of the plug body, and the composite brazing plug is located at a first position where the threaded section is partially screwed into the heat transfer pipe; continuously heating the inner surface of the blind hole of the plug by a cleaver, transferring heat to the plug body to melt a brazing filler metal layer, and enabling the molten brazing filler metal to enter between the plug body and the heat transfer pipe to form an annular brazing filler metal welding seam; the robot controls the riving knife to continue to rotate the brazing plug, so that the thread section of the brazing plug is located at a second position where the thread section is completely screwed into the heat transfer pipe until the boss section is in contact with the pipe plate and certain pretightening force is formed; the chopper is moved away, a TIG welding device is positioned, a TIG welding head is arranged along the circumferential direction of the heat transfer pipe to heat the boss section and the part of the heat transfer pipe, which is contacted with the heat transfer pipe, so that the part of the boss section, which is used for contacting the bottom end of the heat transfer pipe, close to the thread section, is melted and forms an annular self-melting welding seam after solidification.

Further, in the step that the brazing plug is located at a first position where the threaded section is partially screwed into the heat transfer pipe, the length of the threaded section not entering the heat transfer pipe is two screw pitches, and the screw pitches are the screw pitches of internal threads of the heat transfer pipe.

Further, the chopper is matched with the blind hole for positioning, heat is transferred to the plug body through the chopper, a brazing filler metal layer is melted, after the step that the melted brazing filler metal enters the space between the plug body and the heat transfer pipe, the step of waiting for set time is carried out, inert shielding gas is introduced, and TIG welding is carried out.

Further, the step of disposing the brazing filler metal layer on the plug body includes: adhering the paste brazing filler metal to the outer peripheral surface of the plugging section of the plug body to obtain a paste brazing filler metal layer with the thickness larger than the set thickness, wherein the set thickness is as follows: the ring width of a circular ring formed by the axial projections of the threaded section and the plugging section along the plug body is wide; sintering the plug body provided with the paste brazing filler metal layer to enable micro-metallurgical bonding to occur between the paste brazing filler metal layer and the plugging section; and processing the sintered paste brazing filler metal layer to obtain the annular brazing filler metal layer, wherein the inner ring surface of the brazing filler metal layer is tightly attached to the plugging section, and the diameter of the outer ring surface of the brazing filler metal layer is equal to the small diameter of the internal thread of the heat transfer pipe.

Furthermore, the cleaver has double functions of rotating and heating the plug.

The plugging method of the invention has the following beneficial effects: the brazing filler metal layer is heated and melted, and in the process that the threaded section moves to the first position, the liquid brazing filler metal enters the threaded gap between the threaded section and the heat transfer pipe by utilizing the capillary action of the liquid brazing filler metal, so that the primary sealing of the threaded gap is realized; and then, in the process of continuously moving the threaded section to the second position, on one hand, the effective screwing length of the threaded section and the heat transfer pipe is increased, and the connection reliability of the plug body and the heat transfer pipe is improved, and on the other hand, the screw transmission between the external threads of the threaded section and the internal threads of the heat transfer pipe forms the stirring and extruding effects on the liquid solder, so that air holes in the liquid solder are broken, the defects such as air holes are reduced or avoided, the brazing quality is improved, the welding tightness is ensured, the liquid solder further flows to the thread gap, the thread gap between the threaded section and the heat transfer pipe can be fully filled with the liquid solder as far as possible, the brazing length between the threaded section and the heat transfer pipe is effectively increased after the liquid solder is solidified, and the sealing effect between the plug body and the heat transfer pipe is improved.

The plug material is the same as the heat transfer pipe material, the tail circular boss is tightly attached to the tail end of the heat transfer pipe, and the TIG self-fluxing welding is used for realizing homogeneous welding, so that the defects of brittle phases, cracks and the like are reduced while larger residual stress is avoided, and the performance of a welding joint is effectively improved; the brazing and TIG self-fluxing welding are combined, double protection is generated on the heat transfer pipe, the pipe plugging work is more reliable, and the service life is longer.

The plugging method adopts the composite welding plug to plug the heat transfer pipe at the water supply end, and correspondingly, the plugging method has all the advantages of the composite welding plug, and is not repeated herein.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic view of the structure of a heat transfer tube at a port of a water supply end;

fig. 2 is a schematic structural diagram of a composite welding plug according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating steps of a plugging method according to an embodiment of the present invention;

fig. 4 is a schematic diagram illustrating a step of arranging a solder layer on a plug body by using the composite welding plug according to the embodiment of the present invention.

Description of the reference numerals:

010-a plug body; 020-solder layer; 030-Heat transfer tubes; 031-internal threads; 040-riving knife; 050-tube sheet; 060-TIG welding head;

100-a plugging section; 200-thread segments; 300-boss section; 400-blind hole; 500-a circular table section;

210-external threads; 220-annular step surface;

510-small end face; 520-large end face.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

Fig. 1 is a schematic view of a port structure of a heat transfer pipe 030 at a water supply end. As shown in fig. 1, the heat transfer pipe 030 at the water supply end is fixedly connected to the tube plate 050, and the heat transfer pipe 030 is provided with internal threads 031.

Fig. 2 is a schematic structural diagram of the composite welding plug provided in this embodiment. As shown in fig. 2, the embodiment provides a composite welding plug, which includes a plug body 010 and a brazing filler metal layer 020 disposed around the circumference of the plug body 010, specifically, the plug body 010 includes a plugging section 100, a thread section 200, and a boss section 300 sequentially disposed along an axial direction thereof, the plug body 010 is provided with a blind hole 400, an open end of the blind hole 400 is located at the boss section 300 and extends toward the plugging section 100, the blind hole 400 communicates the boss section 300, the thread section 200, and the plugging section 100, wherein the brazing filler metal layer 020 is fixedly disposed on the plugging section 100; the thread section 200 has external threads 210 matching with internal threads 031 of the heat transfer pipe 030, and the small diameter of the thread section 200 is larger than the maximum diameter of the plugging section 100; the outer diameter of the boss section 300 is not smaller than the small diameter of the internal thread 031 of the heat transfer pipe 030, and the end face of the boss section 300 close to the threaded section 200 is used for abutting against the bottom end of the heat transfer pipe 030; the threaded segment 200 has at least a first position where it is partially screwed into the heat transfer pipe 030 and a second position where it is fully screwed into the heat transfer pipe 030.

When the heat-transfer pipe 030 to the water supply end carries out the shutoff, because the heat-transfer pipe 030 to the water supply end is in and erects the state of putting, so end cap body 010 will follow supreme installation from down and go into heat-transfer pipe 030, and specific installation process is: a robot grasps the plug, so that the riving knife 040 is matched with the blind hole 400 for positioning, the plug body 010 is in spiral fit with the internal thread 031 of the heat transfer pipe 030 through the thread section 200 of the plug body, and the brazing plug is located at a first position where the thread section 200 is partially screwed into the heat transfer pipe 030, as shown in (a) of fig. 3; then, the riving knife 040 continuously heats the inner surface of the plug blind hole 400, so as to transfer heat to the plug body 010, so that the brazing filler metal layer 020 is melted, and the melted brazing filler metal enters between the plug body 010 and the heat transfer pipe 030, so as to form an annular brazing filler metal welding seam, as shown in fig. 3 (b); after the brazing filler metal is completely melted, the robot controls the riving knife 040 to continue to rotate the brazing plug, so that the thread segments 200 of the brazing plug are located at the second position where all the thread segments are screwed into the heat transfer pipe 030 until the circular boss at the tail of the plug is in contact with the pipe plate and has a certain pre-tightening force, as shown in (c) in fig. 3; and moving away the riving knife 040, positioning a TIG welding device, and heating the contact part of the boss section 300 and the heat transfer pipe 030 along the circumferential direction of the heat transfer pipe 030 by the TIG welding head 060 so as to melt the contact part of the boss section 300, which is used for contacting the bottom end of the heat transfer pipe 030, and the part of the thread section 200, which is close to the boss section 300, and forming an annular self-fluxing welding seam after solidification.

In the arrangement form of the composite welding plug, the brazing filler metal layer 020 is heated and melted, and in the process that the threaded section 200 moves to the first position, the liquid brazing filler metal enters a thread gap between the threaded section 200 and the heat transfer pipe 030 by utilizing the capillary action of the liquid brazing filler metal, so that the preliminary sealing of the thread gap is realized; then, in the process of continuing to move the threaded section 200 to the second position, on the one hand, the effective screwing length of the threaded section 200 and the heat transfer pipe 030 is increased, the connection reliability of the plug body 010 and the heat transfer pipe 030 is improved, on the other hand, the screw transmission between the external threads 210 of the threaded section 200 and the internal threads 031 of the heat transfer pipe 030 forms stirring and extruding effects on the liquid solder, so that air holes in the liquid solder are broken, the generation of defects such as air holes is reduced or avoided, the brazing quality is improved, the welding sealing performance is ensured, further flowing of the liquid solder to the thread gap is facilitated, the thread gap between the threaded section 200 and the heat transfer pipe 030 can be fully filled with the liquid solder as far as possible, the brazing length between the threaded section 200 and the heat transfer pipe 030 is effectively increased after the liquid solder is solidified, and the sealing effect between the plug body 010 and the heat transfer pipe 030 is increased.

In addition, can realize that mechanical heat pulse chopper 040 brazes and TIG welding combines together, increased end cap body 010 and heat-transfer pipe 030's connected site and welding seam distribution region, still promoted end cap body 010 and heat-transfer pipe 030's joint strength when guaranteeing to weld deeply, moreover, in can also getting into the thread clearance between end cap body and the heat-transfer pipe 030 after the brazing filler metal melts, realized the fixed connection of this position department internal thread 031 and external screw thread 210, prevent that end cap body 010 from becoming flexible, the stifled pipe leakproofness is good, high reliability, long service life. In addition, when the assembly of end cap body 010 and heat-transfer pipe 030 is carried out, the cooperation of robot and blind hole 400 can be utilized, the end cap body 010 is sent into the heat-transfer pipe 030, remote automatic pipe blocking is realized, the phenomenon that workers receive nuclear radiation is avoided, the use safety is high, and the quick pipe blocking operation of the heat-transfer pipe 030 at the water supply end of the steam generator is facilitated.

Moreover, the plug material is the same as the heat transfer pipe material, the boss section 300 is tightly attached to the tail end of the heat transfer pipe, homogeneous welding is achieved by TIG (tungsten inert gas) self-fluxing welding, the defects of brittle phases, cracks and the like are reduced while large residual stress is avoided, and the performance of a welding joint is effectively improved; the brazing and TIG self-fluxing welding are combined, double protection is generated on the heat transfer pipe, the pipe plugging work is more reliable, and the service life is longer.

Specifically, as shown in fig. 1 and 2, in the present embodiment, the small diameter of the internal thread 031 of the heat transfer pipe 030 is d; the small diameter of the thread section 200 is D1, and the large diameter of the thread section 200 is D1; the maximum diameter of the plugging section 100 is d2; the boss section 300 has an outer diameter D2. That is, D1 > D2, D2 ≧ D.

With reference to fig. 2, in this embodiment, the plug body 010 may further include a circular truncated cone section 500, where the circular truncated cone section 500 has a small end surface 510 and a large end surface 520 that are disposed opposite to each other, where the large end surface 520 is fixedly connected to the plugging section 100, and an outer diameter of the large end surface 520 is smaller than a small diameter of an internal thread 031 of the heat transfer pipe 030; the small end surface 510 is used to guide the plug body 010 to be installed inside, for example, the heat transfer pipe 030.

When the composite welding plug is assembled, the circular truncated cone segment 500 of the plug body 010 faces the heat transfer pipe 030, and the small end surface 510 of the circular truncated cone segment 500 positions and guides the assembly process, so that the plug body 010 smoothly enters the heat transfer pipe 030. This setting can improve the assembly efficiency of hybrid welding end cap to improve shutoff efficiency. By making the outer diameter of the large end surface 520 smaller than the small diameter of the female thread 031 of the heat transfer pipe 030, that is: the outer diameter of the large end face 520 is smaller than the small diameter of the thread section 200, so that the outer contour of the circular truncated cone section 500 completely falls into the thread section 200 along the axial direction of the plug body 010, the situation that the inner thread 031 of the heat transfer pipe 030 is damaged due to the fact that the large end face 520 of the circular truncated cone section 500 is too large in the process of assembling the composite welding plug is avoided, and a certain protection effect is achieved on the inner thread 031 of the heat transfer pipe 030.

Referring to fig. 2, in the present embodiment, the blind hole 400 penetrates through the plugging section 100, and the closed end of the blind hole 400 is formed by the large end surface 520 of the circular truncated cone section 500.

Through setting up blind hole 400 to run through shutoff section 100 for riving knife 040 can stretch into the end of shutoff section 100, guarantee that shutoff section 100 all can be heated by the heat that riving knife 040 transmitted along each axial position, thereby make the brazing filler metal layer 020 of encircleing shutoff section 100 melt with comparatively even speed, avoid the situation of the mobility variation that leads to because brazing filler metal layer 020 is heated unevenly locally.

Referring to fig. 2, in the present embodiment, along the radial direction of the plug body 010, an annular step surface 220 is formed at a portion of the threaded section 200 protruding from the plugging section 100, and an end surface of the brazing filler metal layer 020 close to the threaded section 200 abuts against the annular step surface 220.

The arrangement of the annular step surface 220 can play a certain limiting role in the arrangement of the brazing filler metal layer 020, and the brazing filler metal layer 020 is prevented from covering the external thread 210 of the thread section 200 when being arranged. Moreover, this arrangement also provides a certain supporting function for the brazing filler metal layer 020, and prevents the brazing filler metal layer 020 from sliding down and dropping off the plug body 010 when the composite welding plug of the present embodiment is installed into the heat transfer pipe 030.

Specifically, the annular step surface 220 has an annular width of not less than 1.5mm, that is, (d 1-d 2)/2. Gtoreq.1.5 mm. This arrangement can ensure that the annular step surface 220 has a sufficient width to limit and support the solder layer 020.

Preferably, in the present embodiment, the size of the plugging section 100 in the axial direction of the plug body 010 is not smaller than three pitches of the internal thread 031 of the heat transfer pipe 030. This arrangement allows the plugging section 100 to have a sufficient height for the solder layer 020 to be arranged, so that the soldering effect is ensured.

Preferably, in the present embodiment, the size of the thread segment 200 is not smaller than four pitches of the internal thread 031 of the heat transfer pipe 030 in the axial direction of the stopper body 010. This arrangement allows the threaded segment 200 to have a sufficient engagement length with the internal thread 031 of the heat transfer pipe 030 when the plug body 010 is screwed to the heat transfer pipe 030.

Preferably, in the present embodiment, the size of the boss segment 300 is not greater than 3mm along the axial direction of the plug body 010. That is, the thickness of the boss section 300 is not more than 3mm. This arrangement reduces the amount of exposed structure at the end of the heat transfer pipe 030 after the composite welding plug of the present embodiment has plugged the heat transfer pipe 030.

Referring to fig. 2, in the present embodiment, the minimum wall thickness of the plugging section 100 is not less than 1.5mm. This setting has guaranteed the structural strength of shutoff section 100, avoids this embodiment hybrid welding end cap when using, and shutoff section 100 appears buckling, splitting.

Fig. 3 is a schematic step diagram of the plugging method provided in this embodiment. As shown in fig. 3, the present embodiment further provides a plugging method for plugging the heat transfer pipe 030 at the water supply end by using the composite welding plug, including the following steps:

the first step is as follows: a robot grasps the plug, so that the riving knife 040 is matched with the blind hole 400 for positioning, the plug body 010 is in spiral matching with an internal thread 031 of the heat transfer pipe 030 through a thread section 200 of the plug body, and the brazing plug is located at a first position where the thread section 200 is partially screwed into the heat transfer pipe 030, as shown in (a) of fig. 3; the second step is that: then, the riving knife 040 continuously heats the inner surface of the blind plug hole 400, heat is transferred to the plug body 010, so that the solder layer 020 is melted, and the melted solder enters between the plug body 010 and the heat transfer pipe 030 to form an annular solder weld, as shown in (b) of fig. 3; the third step: after the brazing filler metal is completely melted, the robot controls the riving knife 040 to continue to rotate the brazing plug, so that the thread section 200 of the brazing plug is located at a second position where the thread section is completely screwed into the heat transfer pipe 030 until the circular boss at the tail part of the plug is in contact with the pipe plate and has a certain pretightening force, as shown in (c) of fig. 3; the fourth step: and moving away the riving knife 040, positioning a TIG welding device, and heating the contact part of the boss section 300 and the heat transfer pipe 030 along the circumferential direction of the heat transfer pipe 030 by the TIG welding head 060 so as to melt the contact part of the boss section 300, which is used for contacting the bottom end of the heat transfer pipe 030, and the part of the thread section 200, which is close to the boss section 300, and forming an annular self-fluxing welding seam after solidification.

The plugging method adopts the composite welding plug to plug the heat transfer pipe 030 at the water supply end, and accordingly, the plugging method has all the advantages of the composite welding plug, and the detailed description is omitted.

In addition, through forming two circles of welding seams simultaneously in the periphery of end cap body 010, wherein, the round is the brazing filler metal welding seam that forms between the screw thread section 200 and the internal thread 031 of heat-transfer pipe 030, and another circle is the self-fluxing welding seam that forms in the two linking department of screw thread section 200 and boss section 300, has played effectual supporting role to end cap body 010 in heat-transfer pipe 030 inside, has improved end cap body 010's installation stability.

Moreover, the secondary welding of the plug body 010 is realized by utilizing the self-melting of the plug body 010, and other welding materials do not need to be added, so that the situation that the sealing cannot be realized due to the fact that the welding materials are different from the material of the plug body 010 is avoided. Meanwhile, the self-fusion welding of the plug body 010 is only performed at the periphery of the plug body 010, so that the middle main body structure of the plug body 010 is not affected, and the completed brazing filler metal welding seam is not affected.

In this embodiment, when the plug body 010 is subjected to self-fusion welding, a portion of the thread section 200 close to the boss section 300 is melted, that is, when the heat transfer pipe 030 is plugged, the thread section 200 at least performs the following two functions: is connected with the internal thread 031 of the heat transfer pipe 030, so that the plug body 010 is in spiral fit with the heat transfer pipe 030; the teeth of the threaded section 200 are self-melted, and under the matching action of the teeth of the threaded section 200 and the teeth of the heat transfer pipe 030, the melted teeth are filled into the teeth of the heat transfer pipe 030, so that sealing between the threaded section 200 and the heat transfer pipe 030 is realized. Meanwhile, the boss section plays a role in positioning the plug body 010, and when the riving knife 040 rotates to drive the plug to rotate, the boss section and the bottom end of the heat transfer pipe 030 have certain pretightening force, and then the rotation stops.

Specifically, after the robot controls the riving knife 040 to continue to rotate the brazing plug, so that the thread section 200 of the brazing plug is in the second position where all the thread section is screwed into the heat transfer pipe 030 until the circular ring boss at the tail part of the plug is in contact with the pipe plate and has a certain pretightening force, the method further comprises the following steps: and (5) waiting for a set time, introducing inert shielding gas, and performing TIG welding. Wherein, the set time can be 1min.

Through the arrangement, the molten brazing filler metal has enough time to enter the gap between the plug body 010 and the heat transfer pipe 030, and the reliability of brazing sealing is ensured. In addition, the temperature of the plug body 010 can be reduced to a certain degree by waiting for the set time, so that sufficient solidification of the brazing filler metal is guaranteed, and adverse effects on a brazing filler metal welding seam in a self-fluxing welding stage are reduced.

Fig. 4 is a schematic diagram illustrating a step of disposing a solder layer 020 on the plug body 010 in the composite welding plug according to this embodiment. As shown in fig. 4, the step of providing the plug body 010 with the solder layer 020 (the plug body 010 without the solder layer 020 is shown in fig. 4 (a)) includes: s110: adhering the paste solder to the outer circumferential surface of the plugging section 100 of the plug body 010 to obtain a paste solder layer with a thickness greater than a set thickness, as shown in (b) of fig. 4, where the set thickness is: the ring width of the circular ring formed by the axial projection of the plug body 010 along both the thread section 200 and the plugging section 100 is: setting the thickness = (d 1-d 2)/2; s120: sintering the plug body 010 provided with the paste solder layer to cause micro-metallurgical bonding between the paste solder layer and the plugging section 100, as shown in fig. 4 (c); s130: the sintered paste brazing material layer is processed to obtain an annular brazing material layer 020, an inner replaced surface of the brazing material layer 020 is closely attached to the plugging section 100, and the diameter of an outer annular surface of the brazing material layer 020 is equal to the small diameter of the internal thread 031 of the heat transfer pipe 030, as shown in fig. 4 (d).

This kind utilizes the setting form of paste brazing filler metal preforming brazing filler metal layer 020 earlier, is convenient for brazing filler metal layer 020 and end cap body 010 be connected to, through further sintering process, can guarantee the connection compactness between brazing filler metal layer 020 and end cap body 010, simultaneously, also guarantee that brazing filler metal layer 020 has sufficient density.

In step S120, the plug body 010 adhered with the paste solder layer is placed in a vacuum brazing furnace and sintered in advance, so that the solder and the plug are bonded in a micro-metallurgical manner.

In this embodiment, the solder is not higher than the plugging section 100.

The following is a specific embodiment of the plugging method of the present embodiment.

The first step is as follows: a robot grasps the plug, so that the riving knife 040 is matched with the blind hole 400 for positioning, the plug body 010 is in spiral matching with an internal thread 031 of the heat transfer pipe 030 through a thread section 200 of the plug body, and the brazing plug is located at a first position where the thread section 200 is partially screwed into the heat transfer pipe 030, as shown in (a) of fig. 3; the second step: the riving knife 040 continuously heats the inner surface of the plug blind hole 400, heat is transferred to the plug body 010, the brazing filler metal layer 020 is melted, and the melted brazing filler metal enters between the plug body 010 and the heat transfer pipe 030 to form an annular brazing filler metal welding seam, as shown in fig. 3 (b); the third step: after the brazing filler metal is completely melted, the robot controls the riving knife 040 to continue to rotate the brazing plug, so that the thread section 200 of the brazing plug is located at a second position where the thread section is completely screwed into the heat transfer pipe 030 until the circular boss at the tail part of the plug is in contact with the pipe plate and has a certain pretightening force, as shown in (c) of fig. 3; the fourth step: the splitting knife 040 is removed, the TIG welding device is positioned, the TIG welding head 060 heats the contact part of the boss section 300 and the heat transfer pipe 030 along the circumferential direction of the heat transfer pipe 030, so that the contact part of the boss section 300, which is used for contacting the bottom end of the heat transfer pipe 030, and the part, which is close to the boss section 300, of the thread section 200 are melted, after solidification, an annular self-melting welding seam is formed, and the pipe blocking work of the water supply end 030 is completed.

In this embodiment, the specific structure of the TIG welding head 060 and how to perform 360 ° rotation welding are available to those skilled in the art according to the prior art, which is not an improvement point of the present application and therefore will not be described again.

In conclusion, the invention has the following beneficial effects: the integral plug is adopted, so that the structure is simple, the brazing filler metal layer 020 is convenient to preset, and the installation is easy; the plugging method is simple and convenient to operate, the mechanical heat pulse chopper 040 brazing and TIG welding are combined, the welding depth is guaranteed, meanwhile, the bonding strength of a welding joint is improved, the pipe plugging tightness is good, the reliability is high, the service life is long, remote automatic pipe plugging can be achieved by using a robot, personnel are prevented from being subjected to nuclear radiation, and the quick pipe plugging can be carried out on the heat transfer pipe at the water supply end of the steam generator.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected by one skilled in the art without departing from the spirit and scope of the invention, as defined in the appended claims.

Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.

In the above embodiments, the descriptions of the orientations such as "upper", "lower", "side", and the like are based on the drawings.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. The composite welding plug is characterized by comprising a plug body (010) and a brazing filler metal layer (020) arranged around the circumference of the plug body (010), wherein the plug body (010) comprises a plugging section (100), a thread section (200) and a boss section (300) which are sequentially arranged along the axial direction of the plug body, a blind hole (400) is formed in the plug body (010), the open end of the blind hole (400) is located on the boss section (300) and extends towards the plugging section (100), the blind hole (400) is communicated with the boss section (300), the thread section (200) and the plugging section (100), and the brazing filler metal layer (020) is fixedly arranged on the plugging section (100); the thread section (200) is provided with an external thread (210) matched with an internal thread (031) of the heat transfer pipe (030), the small diameter of the thread section (200) is larger than the maximum diameter of the plugging section (100), and the thread section (200) is at least provided with a first position which is partially screwed into the heat transfer pipe (030) and a second position which is fully screwed into the heat transfer pipe (030); the outer diameter of the boss section (300) is not smaller than the small diameter of an internal thread (031) of the heat transfer pipe (030), and the end face, close to the thread section (200), of the boss section (300) is used for being abutted to the bottom end of the heat transfer pipe.

2. The composite welding plug according to claim 1, wherein the plug body (010) further comprises a truncated cone section (500), the truncated cone section (500) has a small end surface (510) and a large end surface (520) which are oppositely arranged, wherein the large end surface (520) is fixedly connected with the plugging section (100), and the outer diameter of the large end surface (520) is smaller than the small diameter of the internal thread (031) of the heat transfer pipe (030); the small end face (510) is used for guiding the plug body (010) to be installed in the heat transfer pipe (030).

3. The composite welding plug as claimed in claim 2, characterized in that the blind hole (400) extends through the plug section (100), the closed end of the blind hole (400) being formed by the large end face (520).

4. The composite welding plug according to claim 1, wherein, in the radial direction of the plug body (010), an annular step surface (220) is formed at a position of the threaded section (200) protruding out of the plugging section (100), and an end surface of the brazing filler metal layer (020) close to the threaded section (200) abuts against the annular step surface (220).

5. The composite welding plug as defined in claim 1, wherein the blocking segment (100) has a size not smaller than three pitches of the internal thread (031) of the heat transfer pipe (030) in the axial direction of the plug body (010); and/or the size of the thread section (200) is not smaller than four thread pitches of internal threads (031) of the heat transfer pipe (030) along the axial direction of the plug body (010); and/or the size of the boss section (300) is not more than 3mm along the axial direction of the plug body (010).

6. The composite welding plug as claimed in claim 1, wherein the plug body (010) is made of the same material as the heat transfer pipe (030).

7. A plugging method for plugging a heat transfer pipe (030) at a water feed end using the composite welding plug as claimed in any one of claims 1 to 6, comprising the steps of:

the plug is grabbed by a robot, the riving knife (040) is matched with the blind hole (400) for positioning, the plug body (010) is in spiral fit with the internal thread (031) of the heat transfer pipe (030) through the thread section (200) of the plug body, and the composite brazing plug is located at the first position where the thread section (200) is partially screwed into the heat transfer pipe (030);

the inner surface of the blind hole (400) of the plug is continuously heated by the riving knife (040), heat is transferred to the plug body (010), a brazing filler metal layer (020) is melted, and the melted brazing filler metal enters between the plug body (010) and the heat transfer pipe (030) to form an annular brazing filler metal welding seam;

the robot controls the riving knife to continue to rotate the brazing plug, so that the threaded section (200) of the brazing plug is located at a second position where the threaded section is completely screwed into the heat transfer pipe (030) until the boss section (300) is in contact with the pipe plate and has a certain pretightening force;

the method comprises the steps of moving away a riving knife (040), positioning a TIG welding device, heating a boss section (300) and a heat transfer pipe (030) along the circumferential direction of the heat transfer pipe (030) by a TIG welding head (060), melting a part, close to the boss section (300), of a part, in contact with the bottom end of the heat transfer pipe (030), of the boss section (300) and a part, close to the boss section (300), of the thread section (200), and forming an annular self-melting welding seam after solidification.

8. Plugging method according to claim 7, wherein in the step of brazing plug being in a first position where the threaded section (200) is partially screwed into the heat transfer pipe (030), the length of the threaded section (200) not entering the heat transfer pipe (030) is two pitches, which are the pitches of the internal thread (031) of the heat transfer pipe (030).

9. The plugging method according to claim 7, wherein the riving knife (040) has a dual function of rotating and heating the plug, the riving knife (040) is positioned in cooperation with the blind hole (400), heat is transferred to the plug body (010) through the riving knife (040) to melt the brazing filler metal layer (020), and after the step of the molten brazing filler metal entering between the plug body (010) and the heat transfer pipe (030), inert shielding gas is introduced for a set time, and TIG welding is performed.

10. Plugging method according to claim 7, characterized in that the step for providing the brazing filler metal layer (020) to the plug body (010) comprises:

adhering the paste brazing filler metal to the outer peripheral surface of the plugging section (100) of the plug body (010) to obtain a paste brazing filler metal layer with the thickness larger than a set thickness, wherein the set thickness is as follows: the ring width of a circular ring formed by axial projections of the threaded section (200) and the plugging section (100) along the plug body (010);

sintering the plug body (010) provided with the paste brazing filler metal layer to enable micro-metallurgical bonding to occur between the paste brazing filler metal layer and the plugging section (100);

and processing the sintered paste brazing filler metal layer to obtain the annular brazing filler metal layer (020), wherein the inner ring surface of the brazing filler metal layer (020) is tightly attached to the plugging section (100), and the diameter of the outer ring surface of the brazing filler metal layer (020) is equal to the small diameter of the internal thread (031) of the heat transfer pipe (030).

Images