Integral control rod assembly spider welding method

Abstract

The present application relates to the field of fuel assembly, especially to a method for welding integral control rod assembly star frame. The method is as follows: TIG fixed point welding is performed on the insertion position of integral handle body branch wing and connecting rod, all welding points are formed by one-time molding without adding wire, each connecting rod has only one TIG welding point, the welding point is located on the outer side of the upper end of the connecting rod and the branch wing contact part, and an integral star frame is obtained; the welding seam of the integral star frame is coated with brazing filler metal, after completing all coating operations, the center cylinder surface of the integral star frame and the conical head of the 24 connecting rods are coated with stop flux, and then dried; the integral star frame is brazed; the brazing condition is that the vacuum degree is below 0.1 Pa, the temperature starts to rise, and the rising speed is controlled to be 15-20 ℃ / min; when the temperature is heated to 50-100 ℃ lower than the solidus temperature of the brazing filler metal, the temperature is kept for 8-15 min; then the temperature is raised to 950-1030 ℃ at a speed of 8-12 ℃ / min, the temperature is kept for 40-60 min at this temperature; finally, the pressure is filled and fast cooled, and the cooling speed is greater than 11 ℃ / min, and the temperature is cooled to 400 ℃; finally, the furnace is cooled to below 120 ℃, and then the furnace is discharged. The present application ensures the positioning accuracy, controls the welding thermal deformation and the brazing seam quality, and meets the use requirements.

Description

Technical Field

[0001] This invention relates to the field of fuel assemblies, and more particularly to a method for welding a star-shaped frame for an integrated control rod assembly. Background Technology

[0002] The control rod assembly has the functions of reactor startup, shutdown, power conversion, and reactor protection. It consists of a star-shaped frame and several control rods. The star-shaped frame is one of the key components of the control rod assembly. It is mainly used to suspend and position the control rod bundle, ensuring that the control rods can be quickly inserted into the fuel assemblies during an emergency shutdown, and absorbing the residual impact energy at the end of the rod drop stroke to prevent the fuel assemblies from being subjected to excessive impact loads.

[0003] The integrated star-shaped frame is assembled and brazed from a single integrated handle and 24 connecting rods. See attached diagram. Figure 1 The one-piece handle has a star-shaped cross-section, with 16 branches arranged around the central cylinder at a preset angle, all machined in one piece. Twenty-four connecting rods are inserted into the ends or middle of the branches, divided into three types: Connecting Rod I (16 rods), Connecting Rod II (4 rods), and Connecting Rod III (4 rods). This star-shaped frame structure requires high dimensional accuracy and high-quality brazing, while also demanding high standards for the brazing filler metal height and the amount of filler metal adhering to the non-brazing areas. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method for welding the star-shaped frame of an integrated control rod assembly, ensuring positioning accuracy, controlling welding thermal deformation and brazing quality, so as to meet the application requirements.

[0005] This invention provides a method for welding a star-shaped frame of an integrated control rod assembly, comprising the following steps:

[0006] Step 1: Perform TIG spot welding on the insertion points of the integrated handle and branch wings and connecting rods. All welds are formed in one piece without wire. Each connecting rod has only one TIG weld, which is located on the upper outer side of the contact part between the connecting rod and the branch wings, resulting in an integrated star-shaped frame.

[0007] Step 2: Apply brazing filler to the weld seams of the integrated star frame. After completing all coating operations, apply brazing stop agent to the circular surface of the central cylinder of the integrated star frame and the conical heads of the 24 connecting rods, and then dry.

[0008] Step 3: Brazing of the integrated star-shaped frame; the brazing conditions are a vacuum degree below 0.1 Pa, start heating, and control the heating rate at 15-20℃ / min; when heated to 50-100℃ below the solidus temperature of the brazing filler material, hold at this temperature for 8-15 minutes; then raise the temperature to 950-1030℃ at a rate of 8-12℃ / min, and hold at this temperature for 40-60 minutes; finally, pressurize and rapidly cool at a cooling rate greater than 11℃ / min to 400℃; finally, cool in the furnace to below 120℃ before removing from the furnace.

[0009] In one specific embodiment of the present invention, step four is also included:

[0010] Inspect the brazed integrated star frame. If there are any omissions or insufficient coating on the weld, repeat steps two and three to reapply brazing material and braze the star frame again.

[0011] In a specific embodiment of the present invention, step one specifically includes:

[0012] Place the integrated handle branch on the fixture base, insert the connecting rod into the corresponding positioning pin, fasten the fixture positioning plate, adjust the positioning pin at the bottom of the fixture base plate to make the root of the connecting tube and the corresponding position of the integrated handle branch fit together and fix it.

[0013] TIG spot welding is performed at the intersection of the handle branch and the connecting rod. All welds are formed in one piece without wire and the welds must not extend beyond the outline of the connecting rod. Each connecting rod has only one TIG weld.

[0014] All welds should be free of defects such as porosity, cracks, slag inclusions, and tungsten inclusions. The 24 connecting rods of the assembly should fit snugly against the root of the corresponding branch and be in the correct position.

[0015] In a specific embodiment of the present invention, step two specifically includes:

[0016] Check the position accuracy of the positioning pins of the brazing fixture to ensure they meet the precision requirements;

[0017] Clean the brazing fixtures and other auxiliary tools thoroughly.

[0018] Install the fixed-point welded integrated star frame correctly onto the brazing fixture and secure it with the tension screw;

[0019] Apply coating to all brazed joints in a clockwise sequence, using a straight-end coating method.

[0020] After completing all the coating operations, apply a solder resist agent to the circular surface of the central cylinder of the integrated star-shaped frame and the conical heads of the 24 connecting rods;

[0021] Dry it.

[0022] In one specific embodiment of the present invention, the brazing fixture and other auxiliary tools are cleaned with acetone or alcohol.

[0023] In one specific embodiment of the present invention, the drying process specifically includes:

[0024] Place in a 50℃~80℃ incubator to dry for 15~20 minutes.

[0025] In one specific embodiment of the present invention, step three specifically comprises:

[0026] Inspect the vacuum heat treatment furnace to ensure the equipment is in good working order and clean.

[0027] The coated and dried integrated star-shaped frame is placed into a vacuum heat treatment furnace; the vacuum inside the furnace is evacuated to below 0.1 Pa; the temperature is raised, and the rate of heating can be controlled at 15-20℃ / min; when the temperature is raised to 50-100℃ below the solidus temperature of the brazing filler, it is held for 10 minutes; then the temperature is raised to 950-1030℃ at a rate of 10℃ / min, and held at this temperature for 40-60 minutes; finally, it is pressurized and rapidly cooled at a rate greater than 11℃ / min to 400℃; finally, it is cooled in the furnace to below 120℃ before being removed from the furnace.

[0028] In one specific embodiment of the present invention, the number of re-brazing is no more than 2 times.

[0029] In one specific embodiment of the present invention, in step one, the connecting rod includes 4 connecting rods III, 4 connecting rods II, and 16 connecting rods I. The welding point of connecting rod I and branch wing is located at the uppermost outermost point of their contact; the welding points of connecting rods II and III and branch wing are located at the uppermost outermost point.

[0030] Compared with the prior art, the integrated control rod assembly star-shaped frame welding method of the present invention has the following advantages:

[0031] Beneficial effects:

[0032] (1) The assembly welding fixture and the TIG fixed spot welding method of each connecting rod are adopted. The assembly operation is simple. While achieving the function of fixing the connecting rod, the connecting rod is ensured to a certain degree of freedom, which improves the assembly efficiency, controls the welding thermal deformation, and ensures that the positioning of the integrated star frame meets the brazing requirements.

[0033] (2) The use of high-precision brazing fixtures, appropriate coating parameters and brazing process parameters ensures the positioning accuracy and brazing quality of the integrated star frame; by applying brazing stop agent to the circular surface of the central cylinder of the integrated star frame and the conical heads of the 24 connecting rods, the adhesion of the brazing filler metal is effectively controlled; the product brazing first-pass yield reaches 99%.

[0034] This technology has been successfully applied to mass production, laying a technical foundation for the development and engineering application of the "Hualong One" control rod assembly. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a star-shaped frame structure;

[0036] Figure 2 A schematic diagram of the star-shaped frame assembly;

[0037] Figure 3 This is a schematic diagram of the spot welding positions for the star-shaped bracket;

[0038] Figure 4 This is a schematic diagram showing the location of the solder coating.

[0039] In the diagram, 1-center cylinder, 2-branch wing, 3-connecting rod I, 4-connecting rod II, 5-connecting rod III, 6-spot welding position, 7-brazing material coating position. Detailed Implementation

[0040] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0041] Embodiments of the present invention disclose a method for welding a star-shaped frame of an integrated control rod assembly, comprising the following steps:

[0042] Step 1: Perform TIG spot welding on the insertion points of the integrated handle and branch wings and connecting rods. All welds are formed in one piece without wire. Each connecting rod has only one TIG weld, which is located on the upper outer side of the contact part between the connecting rod and the branch wings, resulting in an integrated star-shaped frame.

[0043] Specifically: Place the integrated handle branch on the fixture base, insert the connecting rod into the corresponding positioning pin, fasten the fixture positioning plate, adjust the positioning pin at the bottom of the fixture base plate so that the root of the connecting tube and the corresponding position of the integrated handle branch are in contact and fixed.

[0044] The connecting rods include 4 connecting rods III, 4 connecting rods II, and 16 connecting rods I;

[0045] TIG spot welding is performed at the intersection of the handle branch and the connecting rod. All welds are formed in one piece without wire and the welds must not extend beyond the outline of the connecting rod. Each connecting rod has only one TIG weld. The weld between connecting rod I and the branch is located at the upper end of the outermost contact point between the two. The welds between connecting rod II and connecting rod III and the branch are located at the uppermost outermost point.

[0046] All welds should be free of defects such as porosity, cracks, slag inclusions, and tungsten inclusions. The 24 connecting rods of the assembly should fit snugly against the root of the corresponding branch and be in the correct position.

[0047] Step 2: Apply brazing filler to the weld seams of the integrated star frame. After completing all coating operations, apply brazing stop agent to the circular surface of the central cylinder of the integrated star frame and the conical heads of the 24 connecting rods, and then dry.

[0048] Specifically, it includes:

[0049] Check the position accuracy of the positioning pins of the brazing fixture to ensure they meet the precision requirements;

[0050] Clean the brazing fixtures and other auxiliary tools thoroughly.

[0051] Install the fixed-point welded integrated star frame correctly onto the brazing fixture and secure it with the tension screw;

[0052] Apply coating to all brazed joints in a clockwise sequence, using a straight-end coating method.

[0053] After completing all the coating operations, apply a solder resist agent to the circular surface of the central cylinder of the integrated star-shaped frame and the conical heads of the 24 connecting rods;

[0054] Drying is then carried out. The drying conditions are: maintaining the temperature at 50℃~80℃ for 15~20 minutes.

[0055] Step 3: Brazing of the integrated star-shaped frame; the brazing conditions are a vacuum degree below 0.1 Pa, start heating, and control the heating rate at 15-20℃ / min; when heated to 50-100℃ below the solidus temperature of the brazing filler material, hold at this temperature for 8-15 minutes; then raise the temperature to 950-1030℃ at a rate of 8-12℃ / min, and hold at this temperature for 40-60 minutes; finally, pressurize and rapidly cool at a cooling rate greater than 11℃ / min to 400℃; finally, cool in the furnace to below 120℃ before removing from the furnace.

[0056] Brazing is performed inside a vacuum heat treatment furnace. Inspect the vacuum heat treatment furnace to ensure that the equipment is in good working order and clean.

[0057] The preferred brazing conditions are as follows: the vacuum inside the furnace is evacuated to below 0.1 Pa; the temperature is raised at a rate of 15-20°C / min; when the temperature is 50-100°C below the solidus temperature of the brazing filler material, it is held for 10 minutes; then the temperature is raised to 950-1030°C at a rate of 10°C / min, and held at this temperature for 40-60 minutes; finally, the temperature is rapidly cooled under pressure at a rate greater than 11°C / min to 400°C; and finally, the temperature is cooled to below 120°C in the furnace before being removed from the furnace.

[0058] It also includes step four:

[0059] Inspect the brazed integrated star frame. If there are any omissions or insufficient coating on the weld, repeat steps two and three to reapply brazing material and braze the star frame again.

[0060] The number of re-brazing operations shall not exceed 2.

[0061] To further understand the present invention, the star-shaped frame welding method for the integrated control rod assembly provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0062] Example 1

[0063] Step 1: Assemble and spot weld the integrated star-shaped frame.

[0064] The Chinese utility model patent with publication number CN 216264244 U, "An integrated connecting handle assembly spot welding fixture", is used as the fixture for assembly spot welding.

[0065] Place the one-piece handle on the base of the clamp, then attach the 4 connecting rods III, 4 connecting rods II, and 16 connecting rods I according to the attached... Figure 2 The 24 connecting rods are installed into their corresponding positioning pins at their respective assembly positions. The positioning plate on the fixture is then fastened, and the positioning pins at the bottom of the fixture base plate are adjusted so that the roots of the 24 connecting rods are aligned with the corresponding positions of the handle and the branch wings, and then fixed in place.

[0066] TIG spot welding is performed at the intersection of the handle branch and the connecting rod. All welds are formed in one piece without wire, and the welds must not extend beyond the outline of the connecting rod. Each connecting rod has only one TIG weld; the weld locations are shown in the appendix. Figure 3 The weld point between connecting rod I and the branch wing is located at the uppermost point of their outermost contact; the weld points between connecting rods II and III and the branch wing are located at the uppermost point of their outermost contact.

[0067] All welds should be free of defects such as porosity, cracks, slag inclusions, and tungsten inclusions. The 24 connecting rods of the assembly should fit snugly against the root of the corresponding branch and be in the correct position.

[0068] Step 2: Apply brazing filler to the weld seams of the integrated star-shaped frame.

[0069] Check the position accuracy of the positioning pins of the brazing fixture; they should meet the accuracy requirements.

[0070] Clean the brazing fixture and other auxiliary tools and equipment with acetone or alcohol to ensure the stability of the fixture during the brazing process.

[0071] Install the fixed-point welded integrated star frame correctly onto the brazing fixture and secure it with tension screws.

[0072] Adjust the paint pressure and paint speed to ensure continuous and stable paint output from the paint gun.

[0073] The brazing filler metal is applied using a straight-end coating method, proceeding clockwise on all brazed joints while controlling the amount of coating applied. See the attached diagram for the brazing filler metal coating locations. Figure 4 .

[0074] If the brazing filler metal gets onto areas that are not intended for soldering, it should be wiped clean. If insufficient filler metal or missed areas are found, it should be reapplied promptly.

[0075] After completing all the coating operations, apply a solder resist to the circular surface of the connecting handle and the conical heads of the 24 finger rods to prevent the solder from flowing to non-soldering areas.

[0076] Place in a 50℃ incubator to dry for 20 minutes.

[0077] Step 3: Brazing of the integrated star-shaped frame.

[0078] Inspect the vacuum heat treatment furnace to ensure the equipment is in good working order and clean.

[0079] The coated and dried integrated star-shaped frame is placed into a vacuum heat treatment furnace; the vacuum inside the furnace is evacuated to below 0.1 Pa; the temperature is raised, and the rate of heating can be controlled at 20℃ / min; when heated to 100℃ below the solidus temperature of the brazing filler, it is held for 10 minutes; then it is raised to 1030℃ at a rate of 10℃ / min and held at this temperature for 40 minutes; finally, it is pressurized and rapidly cooled at a rate greater than 11℃ / min to 400℃; finally, it is cooled in the furnace to below 120℃ before being removed from the furnace.

[0080] Upon inspection of the brazed integrated star-shaped frame, it was found that the weld seam had areas with insufficient brazing filler or incomplete coating. Steps two and three were repeated to reapply brazing filler and re-braze the star-shaped frame. The re-brazed integrated star-shaped frame was inspected and found to have good welding quality and dimensional accuracy meeting requirements.

[0081] Example 2

[0082] Step 1: Assemble and spot weld the integrated star-shaped frame.

[0083] The Chinese utility model patent with publication number CN 216264244 U, "An integrated connecting handle assembly spot welding fixture", is used as the fixture for assembly spot welding.

[0084] Place the one-piece handle on the base of the clamp, then attach the 4 connecting rods III, 4 connecting rods II, and 16 connecting rods I according to the attached... Figure 2 The 24 connecting rods are installed into their corresponding positioning pins at their respective assembly positions. The positioning plate on the fixture is then fastened, and the positioning pins at the bottom of the fixture base plate are adjusted so that the roots of the 24 connecting rods are aligned with the corresponding positions of the handle and the branch wings, and then fixed in place.

[0085] TIG spot welding is performed at the intersection of the handle branch and the connecting rod. All welds are formed in one piece without wire, and the welds must not extend beyond the outline of the connecting rod. Each connecting rod has only one TIG weld; the weld locations are shown in the appendix. Figure 3 The weld point between connecting rod I and the branch wing is located at the uppermost point of their outermost contact; the weld points between connecting rods II and III and the branch wing are located at the uppermost point of their outermost contact.

[0086] All welds should be free of defects such as porosity, cracks, slag inclusions, and tungsten inclusions. The 24 connecting rods of the assembly should fit snugly against the root of the corresponding branch and be in the correct position.

[0087] Step 2: Apply brazing filler to the weld seams of the integrated star-shaped frame.

[0088] Check the position accuracy of the positioning pins of the brazing fixture; they should meet the accuracy requirements.

[0089] Clean the brazing fixture and other auxiliary tools and equipment with acetone or alcohol to ensure the stability of the fixture during the brazing process.

[0090] Install the fixed-point welded integrated star frame correctly onto the brazing fixture and secure it with tension screws.

[0091] Adjust the paint pressure and paint speed to ensure continuous and stable paint output from the paint gun.

[0092] The brazing filler metal is applied using a straight-end coating method, proceeding clockwise on all brazed joints while controlling the amount of coating applied. See the attached diagram for the brazing filler metal coating locations. Figure 4 .

[0093] If the brazing filler metal gets onto areas that are not intended for soldering, it should be wiped clean. If insufficient filler metal or missed areas are found, it should be reapplied promptly.

[0094] After completing all the coating operations, apply a solder resist to the circular surface of the connecting handle and the conical heads of the 24 finger rods to prevent the solder from flowing to non-soldering areas.

[0095] Place in an 80℃ incubator to dry for 20 minutes.

[0096] Step 3: Brazing of the integrated star-shaped frame.

[0097] Inspect the vacuum heat treatment furnace to ensure the equipment is in good working order and clean.

[0098] The coated and dried integrated star-shaped frame is placed into a vacuum heat treatment furnace; the vacuum inside the furnace is evacuated to below 0.1 Pa; the temperature is raised, and the rate of heating can be controlled at 15℃ / min; when the temperature is raised to 50℃ below the solidus temperature of the brazing filler, it is held for 10 minutes; then the temperature is raised to 950℃ at a rate of 10℃ / min, and held at this temperature for 60 minutes; finally, it is pressurized and rapidly cooled at a rate greater than 11℃ / min to 400℃; finally, it is cooled in the furnace to below 120℃ before being removed from the furnace.

[0099] The brazed integrated star-shaped frame was inspected and found to have good welding results and dimensional accuracy that met the requirements.

[0100] Example 3

[0101] Step 1: Assemble and spot weld the integrated star-shaped frame.

[0102] The Chinese utility model patent with publication number CN 216264244 U, "An integrated connecting handle assembly spot welding fixture", is used as the fixture for assembly spot welding.

[0103] Place the one-piece handle on the base of the clamp, then attach the 4 connecting rods III, 4 connecting rods II, and 16 connecting rods I according to the attached... Figure 2 The 24 connecting rods are installed into their corresponding positioning pins at their respective assembly positions. The positioning plate on the fixture is then fastened, and the positioning pins at the bottom of the fixture base plate are adjusted so that the roots of the 24 connecting rods are aligned with the corresponding positions of the handle and the branch wings, and then fixed in place.

[0104] TIG spot welding is performed at the intersection of the handle branch and the connecting rod. All welds are formed in one piece without wire, and the welds must not extend beyond the outline of the connecting rod. Each connecting rod has only one TIG weld; the weld locations are shown in the appendix. Figure 3 The weld point between connecting rod I and the branch wing is located at the uppermost point of their outermost contact; the weld points between connecting rods II and III and the branch wing are located at the uppermost point of their outermost contact.

[0105] All welds should be free of defects such as porosity, cracks, slag inclusions, and tungsten inclusions. The 24 connecting rods of the assembly should fit snugly against the root of the corresponding branch and be in the correct position.

[0106] Step 2: Apply brazing filler to the weld seams of the integrated star-shaped frame.

[0107] Check the position accuracy of the positioning pins of the brazing fixture; they should meet the accuracy requirements.

[0108] Clean the brazing fixture and other auxiliary tools and equipment with acetone or alcohol to ensure the stability of the fixture during the brazing process.

[0109] Install the fixed-point welded integrated star frame correctly onto the brazing fixture and secure it with tension screws.

[0110] Adjust the paint pressure and paint speed to ensure continuous and stable paint output from the paint gun.

[0111] The brazing filler metal is applied using a straight-end coating method, proceeding clockwise on all brazed joints while controlling the amount of coating applied. See the attached diagram for the brazing filler metal coating locations. Figure 4 .

[0112] If the brazing filler metal gets onto areas that are not intended for soldering, it should be wiped clean. If insufficient filler metal or missed areas are found, it should be reapplied promptly.

[0113] After completing all the coating operations, apply a solder resist to the circular surface of the connecting handle and the conical heads of the 24 finger rods to prevent the solder from flowing to non-soldering areas.

[0114] Place in a 60℃ incubator to dry for 20 minutes.

[0115] Step 3: Brazing of the integrated star-shaped frame.

[0116] Inspect the vacuum heat treatment furnace to ensure the equipment is in good working order and clean.

[0117] The coated and dried integrated star-shaped frame is placed into a vacuum heat treatment furnace; the vacuum inside the furnace is evacuated to below 0.1 Pa; the temperature is raised, and the rate of heating can be controlled at 18°C / min; when heated to 80°C below the solidus temperature of the brazing filler, it is held for 10 minutes; then the temperature is raised to 1000°C at a rate of 10°C / min, and held at this temperature for 50 minutes; finally, it is pressurized and rapidly cooled at a rate greater than 11°C / min to 400°C; finally, it is cooled in the furnace to below 120°C before being removed from the furnace.

[0118] The brazed integrated star-shaped frame was inspected and found to have good welding results and dimensional accuracy that met the requirements.

[0119] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0120] The above description of the disclosed embodiments enables those 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 invention is not 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

1. A method for welding a star-shaped frame to an integrated control rod assembly, characterized in that, Includes the following steps: Step 1: Perform TIG spot welding on the insertion points of the integrated handle and branch wings and connecting rods. All welds are formed in one piece without wire. Each connecting rod has only one TIG weld, which is located on the upper outer side of the contact part between the connecting rod and the branch wings, resulting in an integrated star-shaped frame. Step 2: Apply brazing filler to the weld seams of the integrated star frame. After completing all coating operations, apply brazing stop agent to the circular surface of the central cylinder of the integrated star frame and the conical heads of the 24 connecting rods, and then dry. Step 3: Brazing of the integrated star-shaped frame; the brazing conditions are a vacuum degree below 0.1 Pa, start heating, and control the heating rate at 15-20℃ / min; when heated to 50-100℃ below the solidus temperature of the brazing filler material, hold at this temperature for 8-15 minutes; then raise the temperature to 950-1030℃ at a rate of 8-12℃ / min, and hold at this temperature for 40-60 minutes; finally, pressurize and rapidly cool at a cooling rate greater than 11℃ / min to 400℃; finally, cool in the furnace to below 120℃ before removing from the furnace.

2. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 1, characterized in that, It also includes step four: Inspect the brazed integrated star frame. If there are any omissions or insufficient coating on the weld, repeat steps two and three to reapply brazing material and braze the star frame again.

3. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 1, characterized in that, Step one specifically includes: Place the integrated handle branch on the fixture base, insert the connecting rod into the corresponding positioning pin, fasten the fixture positioning plate, adjust the positioning pin at the bottom of the fixture base plate to make the root of the connecting tube and the corresponding position of the integrated handle branch fit together and fix it. TIG spot welding is performed at the intersection of the handle branch and the connecting rod. All welds are formed in one piece without wire and the welds must not extend beyond the outline of the connecting rod. Each connecting rod has only one TIG weld. All welds should be free of defects such as porosity, cracks, slag inclusions, and tungsten inclusions. The 24 connecting rods of the assembly should fit snugly against the root of the corresponding branch and be in the correct position.

4. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 1, characterized in that, Step two specifically includes: Check the position accuracy of the positioning pins of the brazing fixture to ensure they meet the precision requirements; Clean the brazing fixtures and other auxiliary tools thoroughly. Install the fixed-point welded integrated star frame correctly onto the brazing fixture and secure it with the tension screw; Apply coating to all brazed joints in a clockwise sequence, using a straight-end coating method. After completing all the coating operations, apply a solder resist agent to the circular surface of the central cylinder of the integrated star-shaped frame and the conical heads of the 24 connecting rods; Dry it.

5. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 4, characterized in that, Clean the brazing fixtures and other auxiliary tools with acetone or alcohol.

6. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 1, characterized in that, The drying process specifically includes: Place in a 50℃~80℃ incubator to dry for 15~20 minutes.

7. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 1, characterized in that, Step three specifically involves: Inspect the vacuum heat treatment furnace to ensure the equipment is in good working order and clean. The coated and dried integrated star-shaped frame is placed into a vacuum heat treatment furnace; the vacuum inside the furnace is evacuated to below 0.1 Pa; the temperature is raised, and the rate of heating can be controlled at 15-20℃ / min; when the temperature is raised to 50-100℃ below the solidus temperature of the brazing filler, it is held for 10 minutes; then the temperature is raised to 950-1030℃ at a rate of 10℃ / min, and held at this temperature for 40-60 minutes; finally, it is pressurized and rapidly cooled at a rate greater than 11℃ / min to 400℃; finally, it is cooled in the furnace to below 120℃ before being removed from the furnace.

8. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 2, characterized in that, The number of re-brazing operations shall not exceed 2.

9. The method for welding the star-shaped frame of the integrated control rod assembly according to claim 1, characterized in that, In step one, the connecting rod includes 4 connecting rods III, 4 connecting rods II, and 16 connecting rods I. The welding point of connecting rod I to the branch is located at the uppermost outermost point of the contact between the two; the welding points of connecting rods II and III to the branch are located at the uppermost outermost point.

Images