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 welded plug and a plugging method.

Background technique

The steam generator is one of the most critical equipment in the high-temperature gas-cooled reactor nuclear power system, and the corrosion and damage of the heat transfer tube at the feed water end of the steam generator has always been the main factor for the unplanned shutdown of the nuclear power plant and the loss of the capacity factor of the power plant. The heat transfer tube at the feed water end of the steam generator is an important part of the pressure boundary of the primary circuit and an important barrier to prevent the leakage of radioactive fission products. Its total area accounts for 80% of the pressure boundary of the primary circuit coolant system. During the service process, the heat transfer tube at the water supply end is washed by high temperature, high pressure and high radiation dose medium for a long time, which will cause mechanical damage or chemical damage, resulting in damage to the heat transfer tube at the water supply end, resulting in the leakage of radioactive coolant, causing serious damage. Social adverse repercussions and huge economic losses. The heat transfer tube at the water supply end of the steam generator is the weakest link in the pressure-bearing boundary of the primary circuit. The current design cannot completely avoid the degradation of the heat transfer tube at the water supply end. According to statistics, nearly half of the steam generators in nuclear power plants in the world are damaged In progress.

When the heat transfer tube at the feed water end is severely degraded, the tube plugging method is usually used to prevent the secondary side fluid from being contaminated by radiation.

Commonly used pipe plugging techniques include explosive pipe plugging, welding pipe plugging and mechanical pipe plugging. Among them, due to the high residual stress, the explosive plugging is easy to cause stress corrosion, and it is basically no longer used; the mechanical plugging process is simple, and the time required for plugging is very short. It is widely used in service plugging services, but the structure of the plug is complicated. ; Although welding plugging is widely used, there are problems of insufficient welding depth and low bonding strength during use.

Contents of the invention

The first object of the present invention is to provide a composite welding plug to solve the technical problems of insufficient welding depth and low bonding strength in existing welding plugging methods.

The composite welding plug provided by the present invention includes a plug body and a solder layer arranged around the plug body in the circumferential direction, and the plug body includes a plugging section, a threaded section and a convex section arranged in sequence along the axial direction. platform section, the plug body is provided with a blind hole, the open end of the blind hole is located at the boss section, and extends toward the direction of the plugging section, the blind hole communicates with the boss section, the The threaded section and the plugging section, wherein the solder layer is fixedly arranged on the plugging section; the threaded section has an external thread that matches the internal thread of the heat transfer tube, and the threaded section has The minor diameter is greater than the maximum diameter of the plugging section, and the threaded section has at least a first position where it is partially screwed into the heat transfer tube and a second position where it is completely screwed into the heat transfer tube; The outer diameter is not smaller than the minor diameter of the internal thread of the heat transfer tube, and the end surface of the boss section close to the threaded section is used to abut against the bottom end of the heat transfer tube.

Further, the plug body also includes a circular truncated section, the circular truncated section has a small end surface and a large end surface arranged opposite to each other, wherein the large end surface is fixedly connected to the plugging section, and the outer diameter of the large end surface is The small diameter is smaller than the internal thread of the heat transfer tube; the small end surface is used to guide the plug body to be installed into the heat transfer tube.

Further, the blind hole runs through the plugging section, and the closed end of the blind hole is formed by the large end surface.

Further, along the radial direction of the plug body, the portion of the threaded section protruding from the plugging section forms an annular stepped surface, and the solder layer is close to the end surface of the threaded section and the annular stepped surface. Face to face.

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

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

Further, along the axial direction of the plug body, the size of the plugging section is not less than three pitches of the internal thread of the heat transfer tube; and/or, along the axial direction of the plug body, the The size of the threaded section is not less than four pitches of the internal thread of the heat transfer tube; and/or, along the axial direction of the plug body, the size of the boss section is not greater than 3mm.

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

The beneficial effects brought by the composite welding plug of the present invention are:

By setting a composite welding plug mainly composed of a plug body and a solder layer, the plug body includes a plugging section, a thread section and a boss section arranged in sequence along its axial direction, and the brazing filler metal layer is arranged around the plug The circumferential direction of the section, and the boss section is provided with a blind hole connecting the boss section, the threaded section and the plugging section. When it is necessary to block the heat transfer tube at the water supply end, since the heat transfer tube at the water supply end is in a vertical position, the plug body will be installed into the heat transfer tube from bottom to top. The specific installation process is: put the plug body through its The threaded section is spirally matched with the internal thread of the heat transfer tube, so that the plug body is in the first position where the threaded section is partially screwed into the heat transfer tube; after that, the chopper continues to heat the inner surface of the plug groove, and the heat is transferred to the braze through the plug. The brazing material melts, and the liquid brazing material flows downward under the action of gravity and enters between the plug body and the heat transfer tube; after the brazing material is completely melted, the robot controls the chopper to continue rotating the plug body so that the plug body The body is in the second position where all the threaded sections are screwed into the heat transfer tube. At this time, the boss section plays the role of positioning the plug body. After preload, the rotation stops. Then, the TIG welding (Tungsten Inert Gas Welding, non-melting inert gas shielded arc welding) head is positioned so that the TIG welding head heats the position where the boss section is in contact with the bottom end of the heat transfer tube along the circumferential direction of the heat transfer tube, Melt the bottom of the heat exchange tube, the part of the boss section that is in contact with the bottom end of the heat transfer tube, and the part of the threaded section that is close to the boss section. After this part of the material is melted, the plug body and the heat transfer tube Further sealing, so as to achieve the purpose of sealing the heat transfer tube.

The setting form of this composite welding plug can continuously replenish the solder during thread brazing, effectively improving the welding quality.

In addition, the combination of mechanical heat pulse chopper brazing and TIG welding increases the connection points between the plug body and the heat transfer tube and the distribution area of the weld seam, and improves the welding depth while improving the thickness of the plug body and the heat transfer tube. Moreover, after the solder is melted, it can also enter the thread gap between the plugging body and the heat transfer tube, realizing the fixed connection between the internal thread and the external thread at this position, preventing the plug body from loosening, and sealing the plugging tube. Good performance, high reliability and long life. In addition, when assembling the plug body and the heat transfer tube, the plug body can be sent into the heat transfer tube by using the cooperation of the robot and the blind hole, which realizes the long-distance automatic plugging of the tube and prevents the staff from being exposed to nuclear radiation. It has high safety and is convenient for quick pipe plugging operation on the heat transfer pipe at the feed water end of the steam generator.

The second object of the present invention is to provide a plugging method to solve the technical problems of insufficient welding depth and low bonding strength in existing welding plugging methods.

The plugging method provided by the present invention uses the above-mentioned composite welded plug to plug the heat transfer pipe at the water supply end, including the following steps: the robot grabs the plug, coordinates the chopper with the blind hole for positioning, and the plug body passes through its thread section and the inner thread of the heat transfer tube are spirally matched, and the composite brazing plug is in the first position where the threaded section is partially screwed into the heat transfer tube; the chopper continuously heats the inner surface of the blind hole of the plug, The heat is transferred to the plug body to melt the solder layer, and the melted solder enters between the plug body and the heat transfer tube to form an annular solder joint; the robot controls the chopper to continue to rotate Move the brazing plug so that the threaded section of the brazing plug is in the second position where it is completely screwed into the heat transfer tube until the boss section contacts the tube sheet and has a certain pre-tightening force ; Remove the chopper, position the TIG welding device, and the TIG welding head heats the position where the boss section is in contact with the heat transfer tube along the circumferential direction of the heat transfer tube, so that the boss section is used to be in contact with the heat transfer tube. The portion where the bottom end of the heat transfer tube contacts and the portion of the threaded section close to the boss section are melted, and after solidification, an annular self-fluxing weld seam is formed.

Further, the brazing plug is in the step where the threaded section is partially screwed into the first position of the heat transfer tube, the length of the threaded section not entering the heat transfer tube is two pitches, the The pitch is the pitch of the internal thread of the heat transfer tube.

Further, the rivet is positioned in cooperation with the blind hole, and the heat is transferred to the plug body through the rivet to melt the solder layer, and the melted solder enters the gap between the plug body and the heat transfer tube After the intermediate steps, wait for the set time, pass inert protective gas, and then perform TIG welding.

Further, the step of arranging the solder layer on the plug body includes: adhering cream solder to the outer peripheral surface of the plugging section of the plug body to obtain a thickness greater than the set thickness. Paste solder layer, wherein, the set thickness is: the ring width of the ring formed by both the threaded section and the plugging section along the axial projection of the plug body; The plug body of the paste solder layer, so that micro-metallurgical bonding occurs between the paste solder layer and the plugging section; the sintered paste solder layer is processed to obtain a ring-shaped The brazing material layer, the inner ring surface of the brazing material layer is in close contact with the plugging section, and the diameter of the outer ring surface of the brazing material layer is equal to the minor diameter of the internal thread of the heat transfer tube.

Further, the riving knife used has dual functions of rotating and heating the plug.

The beneficial effect brought by the plugging method of the present invention is: the brazing filler metal layer is heated and melted, and during the movement of the threaded section to the first position, the capillary action of the liquid brazing filler metal is used to make it enter the thread gap between the threaded section and the heat transfer tube In the middle, the preliminary sealing of the thread gap is realized; after that, as the threaded section continues to move to the second position, on the one hand, the effective screwing length of the threaded section and the heat transfer tube is increased to improve the connection between the plug body and the heat transfer tube. On the other hand, the screw transmission between the external thread of the threaded section and the internal thread of the heat transfer tube forms a stirring and squeezing effect on the liquid solder, which not only squeezes the pores in the liquid solder Break, reduce or avoid the generation of defects such as pores, improve the quality of brazing, so as to ensure the sealing of welding, and also facilitate the further flow of liquid solder to the thread gap, so that the liquid solder can fill the thread section and the thread gap as fully as possible. The thread gap between the heat transfer tubes, so that after the liquid solder solidifies, the brazing length between the threaded section and the heat transfer tube is also effectively increased, increasing the sealing effect between the plug body and the heat transfer tube.

The material of the plug is the same as that of the heat transfer tube, and the ring boss at the end is closely attached to the end of the heat transfer tube. TIG self-fluxing welding is used to achieve homogeneous welding, which avoids large residual stress and reduces brittle phases and cracks, etc. The occurrence of defects can effectively improve the performance of welded joints; the combination of brazing and TIG self-fluxing welding can produce double protection for heat transfer tubes, and the plugging work is more reliable and the service life is longer.

In this plugging method, the above-mentioned composite welded plug is used to plug the heat transfer pipe at the water supply end. Correspondingly, this plugging method has all the advantages of the above-mentioned composite welded plug, which will not be repeated here.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can also obtain other drawings according to the provided drawings without creative work.

Fig. 1 is the structural representation of the heat transfer tube at the water supply end at the port;

Fig. 2 is a structural schematic diagram of a composite welding plug provided by an embodiment of the present invention;

3 is a schematic diagram of the steps of the plugging method provided by the embodiment of the present invention;

Fig. 4 is a schematic diagram of the steps of disposing the solder layer on the plug body of the composite welding plug provided by the embodiment of the present invention.

Explanation of reference signs:

010-plug body; 020-brazing material layer; 030-heat transfer tube; 031-internal thread; 040-river; 050-tube plate; 060-TIG welding head;

100-blocking section; 200-thread section; 300-boss section; 400-blind hole; 500-round table section;

210-external thread; 220-annular step surface;

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

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

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

Fig. 2 is a schematic structural diagram of the composite welded plug provided in this embodiment. As shown in Figure 2, this embodiment provides a composite welding plug, including a plug body 010 and a solder layer 020 arranged around the plug body 010 in the circumferential direction, specifically, the plug body 010 includes To the plugging section 100, the threaded section 200 and the boss section 300 arranged in sequence, the plug body 010 is provided with a blind hole 400, and the open end of the blind hole 400 is located at the boss section 300, and extends toward the direction of the plugging section 100, The blind hole 400 communicates with the boss section 300, the threaded section 200 and the plugging section 100, wherein the solder layer 020 is fixedly arranged on the plugging section 100; the threaded section 200 has an external thread that matches the internal thread 031 of the heat transfer tube 030 210, and the small diameter of the threaded section 200 is greater than the maximum diameter of the plugging section 100; the outer diameter of the boss section 300 is not less than the small diameter of the internal thread 031 of the heat transfer tube 030, and the end surface of the boss section 300 close to the threaded section 200 is used for The bottom end of the heat transfer tube 030 abuts; the threaded section 200 has at least a first position where it is partially screwed into the heat transfer tube 030 and a second position where it is fully screwed into the heat transfer tube 030 .

When it is necessary to plug the heat transfer tube 030 at the water supply end, since the heat transfer tube 030 at the water supply end is in a vertical position, the plug body 010 will be installed into the heat transfer tube 030 from bottom to top. Take the plug, make the chopper 040 cooperate with the blind hole 400 for positioning, the plug body 010 is screwed with the internal thread 031 of the heat transfer tube 030 through its threaded section 200, and make the brazing plug in the threaded section Part 200 is screwed into the first position of the heat transfer tube 030, as shown in (a) in Figure 3; after that, the rivet 040 continues to heat the inner surface of the plug blind hole 400, and transfers heat to the plug body 010, melting the brazing filler metal layer 020, and the molten brazing filler metal enters between the plug body 010 and the heat transfer tube 030 to form an annular brazing filler metal weld, as shown in (b) in FIG. 3 ; After the solder is completely melted, the robot controls the chopper 040 to continue to rotate the brazing plug so that the threaded section 200 of the brazing plug is in the second position where it is completely screwed into the heat transfer tube 030 , until the ring boss at the end of the plug contacts the tube sheet and has a certain pre-tightening force, as shown in (c) in Figure 3; remove the chopper 040, position the TIG welding device, and the TIG welding head 060 along the The heat transfer tube 030 circumferentially heats the portion where the boss section 300 is in contact with the heat transfer tube 030 , so that the portion of the boss section 300 that is in contact with the bottom end of the heat transfer tube 030 and The portion of the threaded section 200 close to the boss section 300 is melted and solidified to form an annular self-fluxing weld.

In the setting form of this composite welding plug, the solder layer 020 is heated and melted, and when the threaded section 200 moves to the first position, the capillary action of the liquid solder is used to make it enter the threaded section 200 and the heat transfer tube 030. In the thread gap, the preliminary sealing of the thread gap is realized; after that, as the thread segment 200 continues to move to the second position, on the one hand, the effective screwing length of the thread segment 200 and the heat transfer tube 030 is increased to improve the sealing effect. The reliability of the connection between the head body 010 and the heat transfer tube 030, on the other hand, the screw transmission between the external thread 210 of the threaded section 200 and the internal thread 031 of the heat transfer tube 030 forms a stirring and squeezing effect on the liquid solder , not only make the pores in the liquid solder be crushed, reduce or avoid the occurrence of defects such as pores, improve the brazing quality, thereby ensuring the sealing of the welding, but also facilitate the further flow of the liquid solder to the thread gap, making the liquid solder The material can fully fill the thread gap between the threaded section 200 and the heat transfer tube 030 as much as possible, so that after the liquid solder is solidified, the brazing length between the threaded section 200 and the heat transfer tube 030 is also effectively increased. The sealing effect between the plug body 010 and the heat transfer tube 030.

In addition, it can realize the combination of mechanical heat pulse rivet 040 brazing and TIG welding, increase the connection points between the plug body 010 and the heat transfer tube 030 and the distribution area of the welding seam, and improve the plug while ensuring the welding depth. The connection strength between the main body 010 and the heat transfer tube 030, moreover, after the solder is melted, it can also enter the thread gap between the sealing body and the heat transfer tube 030, realizing the fixed connection between the internal thread 031 and the external thread 210 at this position , to prevent the plug body 010 from loosening, the plugging tube has good sealing performance, high reliability and long service life. In addition, when assembling the plug body 010 and the heat transfer tube 030, the cooperation between the robot and the blind hole 400 can be used to send the plug body 010 into the heat transfer tube 030, which realizes long-distance automatic tube plugging and avoids the staff It is safe to use due to nuclear radiation, and it is convenient to quickly block the heat transfer pipe 030 at the feed water end of the steam generator.

Furthermore, the material of the plug is the same as that of the heat transfer tube, and the boss section 300 is closely attached to the end of the heat transfer tube. TIG self-fluxing welding is used to achieve homogeneous welding, which reduces the brittle phase and The occurrence of defects such as cracks can effectively improve the performance of welded joints; the combination of brazing and TIG self-fluxing welding can produce double protection for heat transfer tubes, and the plugging work is more reliable and the service life is longer.

Specifically, as shown in Figures 1 and 2, in this embodiment, the minor diameter of the internal thread 031 of the heat transfer tube 030 is d; the minor diameter of the threaded section 200 is d1, and the major diameter of the threaded section 200 is D1; the plugging section The maximum diameter of 100 is d2; the outer diameter of boss section 300 is D2. That is, d1>d2, D2≥d.

Please continue to refer to FIG. 2 , in this embodiment, the plug body 010 may also include a circular truncated section 500 , the circular truncated section 500 has a small end surface 510 and a large end surface 520 arranged opposite to each other, wherein the large end surface 520 is fixedly connected to the plugging section 100 , the outer diameter of the large end face 520 is smaller than the minor diameter of the internal thread 031 of the heat transfer tube 030;

When assembling the composite welded plug, make the circular frustum section 500 of the plug body 010 face the heat transfer tube 030, and the small end surface 510 of the circular frustum section 500 will position and guide the assembly process, so that the plug body 010 can enter the heat transfer tube smoothly. Heat pipe 030 in. This setting can improve the assembly efficiency of the composite welded plug, thereby improving the plugging efficiency. Moreover, by making the outer diameter of the large end surface 520 smaller than the minor diameter of the internal thread 031 of the heat transfer tube 030, that is, the outer diameter of the large end surface 520 is smaller than the minor diameter of the threaded section 200, so that along the axial direction of the plug body 010, the frustum section 500 The outer contour of the truncated section 500 completely falls into the threaded section 200, thereby avoiding the damage to the internal thread 031 of the heat transfer tube 030 caused by the large end surface 520 of the circular platform section 500 during the assembly process of the composite welding plug. The internal thread 031 of the pipe 030 plays a certain protective role.

Please continue to refer to FIG. 2 , in this embodiment, the blind hole 400 runs 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 frustum section 500 .

By arranging the blind hole 400 to pass through the plugging section 100, the rivet 040 can extend into the end of the plugging section 100, ensuring that all positions of the plugging section 100 along the axial direction can be heated by the heat transferred from the rivet 040 , so that the brazing material layer 020 surrounding the plugging section 100 is melted at a relatively uniform speed, and the fluidity deterioration caused by the local uneven heating of the brazing material layer 020 is avoided.

Please continue to refer to FIG. 2. In this embodiment, along the radial direction of the plug body 010, the portion of the threaded section 200 protruding from the plugging section 100 forms an annular stepped surface 220, and the end surface of the solder layer 020 close to the threaded section 200 and the The annular stepped surface 220 abuts against it.

The setting of the annular step surface 220 can limit the setting of the solder layer 020 to a certain extent, preventing the solder layer 020 from covering the external thread 210 of the threaded section 200 when it is set. Moreover, this setting also supports the solder layer 020 to a certain extent, preventing the solder layer 020 from slipping off the plug body 010 from the bottom when the composite welding plug of this embodiment is loaded upward into the heat transfer tube 030 .

Specifically, the ring width of the annular stepped surface 220 is not less than 1.5mm, that is, (d1-d2)/2≧1.5mm. This arrangement can ensure that the annular stepped surface 220 has sufficient width to limit and support the solder layer 020 .

Preferably, in this embodiment, along the axial direction of the plug body 010 , the size of the plugging section 100 is not less than three pitches of the inner thread 031 of the heat transfer tube 030 . This setting makes the plugging section 100 have a sufficient height for the setting of the solder layer 020 to ensure the brazing effect.

Preferably, in this embodiment, along the axial direction of the plug body 010 , the size of the threaded section 200 is not less than four pitches of the inner thread 031 of the heat transfer tube 030 . This setting makes the threaded section 200 of the plug body 010 screwed to the heat transfer tube 030 to have a sufficient matching length with the internal thread 031 of the heat transfer tube 030 .

Preferably, in this embodiment, along the axial direction of the plug body 010 , the size of the boss section 300 is not greater than 3 mm. That is to say, the thickness of the boss section 300 is not greater than 3 mm. This setting makes the structure exposed by the port of the heat transfer tube 030 less after the composite welding plug of this embodiment completes the sealing of the heat transfer tube 030 .

Please continue to refer to FIG. 2 , in this embodiment, the minimum wall thickness of the blocking section 100 is not less than 1.5 mm. This arrangement ensures the structural strength of the plugging section 100 and prevents the plugging section 100 from being bent or broken when the composite welded plug of this embodiment is in use.

Fig. 3 is a schematic diagram of the steps of the plugging method provided in this embodiment. As shown in Figure 3, this embodiment also provides a plugging method, using the composite welded plug to plug the heat transfer pipe 030 at the water supply end, including the following steps:

Step 1: The robot grabs the plug, makes the chopper 040 cooperate with the blind hole 400 for positioning, the plug body 010 spirally cooperates with the internal thread 031 of the heat transfer tube 030 through its threaded section 200, and makes the brazing plug The head is in the first position where the threaded section 200 is partially screwed into the heat transfer tube 030, as shown in (a) in Figure 3; the second step: after that, the rivet 040 continues to heat the inner surface of the plug blind hole 400 , transfer heat to the plug body 010 to melt the solder layer 020, and the melted solder enters between the plug body 010 and the heat transfer tube 030 to form an annular solder weld, as shown in the figure Shown in (b) in 3; the third step: after the solder is completely melted, the robot controls the chopper 040 to continue to rotate the brazing plug so that the threaded section 200 of the brazing plug It is in the second position where it is fully screwed into the heat transfer tube 030, until the ring boss at the end of the plug contacts the tube sheet and has a certain pre-tightening force, as shown in (c) in Figure 3; Step 4: Remove the chopper 040, position the TIG welding device, and the TIG welding head 060 heats the position where the boss section 300 is in contact with the heat transfer tube 030 along the circumferential direction of the heat transfer tube 030, so that the The portion of the boss section 300 that is in contact with the bottom end of the heat transfer tube 030 and the portion of the threaded section 200 close to the boss section 300 are melted and solidified to form an annular self-fluxing weld.

The plugging method uses the above composite welded plug to plug the heat transfer pipe 030 at the water supply end. Correspondingly, this plugging method has all the advantages of the above composite welded plug, which will not be repeated here.

In addition, two rings of welding seams are simultaneously formed on the outer periphery of the plug body 010, wherein one ring is a brazing solder seam formed between the threaded section 200 and the internal thread 031 of the heat transfer tube 030, and the other ring is a solder seam formed between the threaded section 200 and the inner thread 031 of the heat transfer tube 030, and the other ring is a solder seam formed between the threaded section 200 and the inner thread 031 of the heat transfer tube 030. The self-fluxing weld seam formed at the junction of the section 200 and the boss section 300 effectively supports the plug body 010 inside the heat transfer tube 030 and improves the installation stability of the plug body 010 .

Moreover, the secondary welding of the plug body 010 is realized by the self-melting of the plug body 010 without adding other welding materials, which avoids the situation that the sealing cannot be caused due to the different materials of the welding materials and the plug body 010. At the same time, the self-fluxing welding of the plug body 010 is only performed on the outer periphery of the plug body 010, which will not affect the middle body structure of the plug body 010, nor will it affect the completed solder weld.

In this embodiment, when the plug body 010 is self-welded, the portion of the threaded section 200 close to the boss section 300 is melted, that is to say, when the heat transfer tube 030 is blocked, the threaded section 200 at least To the following two functions: connected with the internal thread 031 of the heat transfer tube 030, so that the plug body 010 is screwed with the heat transfer tube 030; Under the cooperative action of the tooth shape of the tube 030 , the melted teeth fill the tooth shape of the heat transfer tube 030 to realize the sealing between the threaded section 200 and the heat transfer tube 030 . At the same time, the boss section plays the role of positioning the plug body 010. When the chopper 040 rotates to drive the plug to rotate so that the boss section and the bottom end of the heat transfer tube 030 have a certain pre-tightening force, the rotation stops.

Specifically, when the robot controls the chopper 040 to continue to rotate the brazing plug, the threaded section 200 of the brazing plug is in the second position where it is completely screwed into the heat transfer tube 030 until the After the ring boss at the end of the plug contacts the tube sheet and has a certain pre-tightening force, it further includes the steps of: waiting for a set time, injecting an inert protective gas, and then performing TIG welding. Wherein, the setting time may be 1 min.

Through this arrangement, the molten brazing material has enough time to enter the gap between the plug body 010 and the heat transfer tube 030, ensuring the reliability of the brazing seal. Moreover, by waiting for the set time, the temperature of the plug body 010 can also be reduced to a certain extent, so as to ensure sufficient solidification of the brazing filler metal and reduce the adverse effect of the self-fluxing welding stage on the brazing filler metal weld.

FIG. 4 is a schematic diagram of the steps of disposing the solder layer 020 on the plug body 010 of the composite welding plug provided in this embodiment. As shown in Figure 4, the steps for disposing the solder layer 020 on the plug body 010 (the plug body 010 without the solder layer 020 is shown in (a) in Figure 4 ) include: S110: put the paste Shaped solder adheres to the outer peripheral surface of the plugging section 100 of the plug body 010 to obtain a paste solder layer with a thickness greater than the set thickness, as shown in (b) in Figure 4, wherein the set thickness is: The ring width of the ring formed by both the threaded section 200 and the plugging section 100 along the axial projection of the plug body 010, that is: set thickness = (d1-d2)/2; S120: sintered with paste The plug body 010 of the solder layer makes micro-metallurgical bonding between the solder paste layer and the plugging section 100, as shown in (c) in Figure 4; S130: Carry out the sintered solder paste layer Processing to obtain a ring-shaped solder layer 020, the inner surface of the solder layer 020 is closely attached to the plugging section 100, and the diameter of the outer ring surface of the solder layer 020 is equal to the small diameter of the internal thread 031 of the heat transfer tube 030 , as shown in (d) in Figure 4.

This method of pre-forming the solder layer 020 with cream solder facilitates the connection between the solder layer 020 and the plug body 010, and, through further sintering, can ensure that the solder layer 020 and the plug body 010 The tightness of the connection between them, at the same time, also ensure that the solder layer 020 has sufficient density.

It should be noted that, in the above step S120, the plug body 010 adhered to the paste solder layer is placed in a vacuum brazing furnace for pre-sintering, so that the brazing material and the plug are micrometallurgically bonded.

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

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

Step 1: The robot grabs the plug, makes the chopper 040 cooperate with the blind hole 400 for positioning, the plug body 010 spirally cooperates with the internal thread 031 of the heat transfer tube 030 through its threaded section 200, and makes the brazing plug The head is at the first position where the threaded section 200 is partly screwed into the heat transfer tube 030, as shown in (a) in FIG. Heat is transferred to the plug body 010 to melt the solder layer 020, and the melted solder enters between the plug body 010 and the heat transfer tube 030 to form an annular solder weld, as shown in Figure 3 Shown in (b); the third step: after the solder is completely melted, the robot controls the chopper 040 to continue to rotate the brazing plug so that the threaded section 200 of the brazing plug is in full Screw into the second position of the heat transfer tube 030 until the ring boss at the end of the plug contacts the tube sheet and has a certain pre-tightening force, as shown in (c) in Figure 3; the fourth step: move The riving knife 040 is used to position the TIG welding device, and the TIG welding head 060 heats the position where the boss section 300 is in contact with the heat transfer tube 030 along the circumferential direction of the heat transfer tube 030, so that the boss section 300 The part used to be in contact with the bottom end of the heat transfer tube 030 and the part of the threaded section 200 close to the boss section 300 are melted, and after solidification, an annular self-fluxing weld is formed, so far the water supply end 030 is completed. Pipe plugging work.

In this embodiment, the specific structure of the TIG welding head 060 and how to perform 360° rotation welding can be obtained by those skilled in the art according to the prior art, which is not an improvement point of the present application, so it will not be repeated here.

In summary, the present invention has the following beneficial effects: the integrated plug is adopted, the structure is simple, it is convenient to preset the solder layer 020, and it is easy to install; The combination of 040 brazing and TIG welding not only ensures the welding depth, but also improves the bonding strength of the welded joints. The pipe plugging has good sealing performance, high reliability, and long life. The use of robots can realize long-distance automatic pipe plugging to avoid personnel being exposed to nuclear accidents. Radiation can quickly block the heat transfer tube of the steam generator feed water end.

Although the present invention is disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the protection scope of the present invention should be based on the scope defined in the claims.

Finally, it should also be noted that in this text, relational terms such as first and second etc. are only used to distinguish one entity or operation from another, and do not necessarily require or imply that these entities or operations, any such actual relationship or order exists. Moreover, the term "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements but also other elements not expressly listed, Or also include elements inherent in such a process, method, article or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

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

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not 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. A composite welding plug, characterized in that it comprises a plug body (010) and a solder layer (020) arranged circumferentially around the plug body (010), the plug body (010) It includes a plugging section (100), a threaded section (200) and a boss section (300) arranged in sequence along its axial direction, the plug body (010) is provided with a blind hole (400), and the blind hole (400 ) is located at the boss section (300), and extends toward the direction of the plugging section (100), and the blind hole (400) communicates with the boss section (300), the threaded section ( 200) and the plugging section (100), wherein the solder layer (020) is fixedly arranged on the plugging section (100); the threaded section (200) has a connection with the heat transfer tube (030) The internal thread (031) is matched with the external thread (210), and the minor diameter of the threaded section (200) is larger than the maximum diameter of the sealing section (100), and the threaded section (200) has at least a partial screw-in The first position of the heat transfer tube (030) and the second position where all the heat transfer tubes (030) are screwed into; the outer diameter of the boss section (300) is not smaller than that of the heat transfer tube (030) The small diameter of the internal thread (031), the end surface of the boss section (300) close to the thread section (200) is used to abut against the bottom end of the heat transfer tube. 2. The composite welding plug according to claim 1, characterized in that, the plug body (010) further includes a circular truncated section (500), and the circular truncated section (500) has small end faces (510) arranged opposite to each other ) and a large end surface (520), wherein the large end surface (520) is fixedly connected to the plugging section (100), and the outer diameter of the large end surface (520) is smaller than the inner diameter of the heat transfer tube (030) The small diameter of the thread (031); the small end surface (510) is used to guide the plug body (010) to be installed into the inside of the heat transfer tube (030). 3. The composite welding plug according to claim 2, characterized in that, the blind hole (400) runs through the plugging section (100), and the closed end of the blind hole (400) is formed by the large end surface (520) formed. 4. The composite welding plug according to claim 1, characterized in that, along the radial direction of the plug body (010), the threaded section (200) protrudes beyond the plugging section (100) An annular stepped surface (220) is formed at the position, and the end surface of the solder layer (020) close to the threaded segment (200) abuts against the annular stepped surface (220). 5. The composite welded plug according to claim 1, characterized in that, along the axial direction of the plug body (010), the size of the plugging section (100) is not smaller than that of the heat transfer tube (030) ) of the internal thread (031) of three pitches; and/or, along the axial direction of the plug body (010), the size of the threaded segment (200) is not smaller than the inner diameter of the heat transfer tube (030) Four pitches of the thread (031); and/or, along the axial direction of the plug body (010), the size of the boss section (300) is not greater than 3 mm. 6. The composite welding plug according to claim 1, characterized in that, the material of the plug body (010) is the same as that of the heat transfer tube (030). 7. A plugging method, characterized in that, using the composite welded plug according to any one of claims 1-6 to plug the heat transfer pipe (030) at the water supply end, comprising the steps of: The robot grabs the plug and positions the chopper (040) in cooperation with the blind hole (400), and the plug body (010) spirally fits with the internal thread (031) of the heat transfer tube (030) through its threaded section (200) , and make the composite brazing plug be in the first position where the threaded section (200) is partially screwed into the heat transfer tube (030); The chopper (040) continuously heats the inner surface of the plug blind hole (400), transfers the heat to the plug body (010), melts the solder layer (020), and the melted solder enters the plug body ( 010) and the heat transfer tube (030), forming an annular solder joint; The robot controls the chopper to continue to rotate the brazing plug, so that the threaded section (200) of the brazing plug is in the second position where it is completely screwed into the heat transfer tube (030), until the The boss section (300) is in contact with the tube sheet and has a certain pre-tightening force; Remove the chopper (040), position the TIG welding device, and the TIG welding head (060) heats the boss section (300) and the heat transfer tube (030) along the circumferential direction of the heat transfer tube (030). The contact position is that the part of the boss section (300) used to contact the bottom end of the heat transfer tube (030) and the part of the threaded section (200) close to the boss section (300) After melting and solidification, a circular self-fluxing weld is formed. 8. The plugging method according to claim 7, characterized in that, the brazing plug is in the step of partially screwing the threaded section (200) into the first position of the heat transfer tube (030), The length of the threaded section (200) not entering the heat transfer tube (030) is two pitches, and the pitch is the pitch of the internal thread (031) of the heat transfer tube (030). 9. The plugging method according to claim 7, characterized in that, the riving knife (040) has dual functions of rotating and heating the plug, and the riving knife (040) cooperates with the blind hole (400) for positioning, by The chopper (040) transfers heat to the plug body (010), melting the solder layer (020), and the melted solder enters between the plug body (010) and the heat transfer tube (030) After the intermediate steps, wait for the set time, pass inert protective gas, and then perform TIG welding. 10. The plugging method according to claim 7, characterized in that the step for arranging the solder layer (020) on the plug body (010) comprises: Paste solder is adhered to the outer peripheral 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, wherein the set thickness is: The ring width of the ring formed by both the threaded section (200) and the plugging section (100) along the axial projection of the plug body (010); Sintering the plug body (010) provided with the paste solder layer, so that micro-metallurgical bonding occurs between the paste solder layer and the plugging section (100); Processing the sintered paste solder layer to obtain the ring-shaped solder layer (020), the inner ring surface of the solder layer (020) is closely attached to the plugging section (100) , the diameter of the outer ring surface of the solder layer (020) is equal to the minor diameter of the internal thread (031) of the heat transfer tube (030).

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