Welding method and welding tool for double-hole tube of control rod guide tube

Abstract

The application provides a welding method and welding tool for a double-hole tube of a control rod guide cylinder, and steps of the method comprise the following steps: S1, cleaning the double-hole tube part groove by using a cleaning agent; S2, assembling a double-hole tube part group into the tool, the double-hole tube part groups are arranged, and the double-hole tube part is fixed on the tool by a fixing nut; S3, putting the tool with the assembled double-hole tube part into a vacuum chamber, and vacuumizing; S4, electron beam spot welding positioning, welding one spot on each end of the welded part, and uniformly distributing the middle spots; S5, performing electron beam single-channel deep welding; S6, performing finish welding; S7, after the welding is completed, exhausting the vacuum chamber, and taking out the tool with the assembled double-hole tube part; and S8, removing the fixing nut, and taking the double-hole tube part assembly from the tool. The application has the effects of reducing welding deformation and ensuring high-quality part batch production.

Description

Technical Field

[0001] This invention belongs to the field of manufacturing technology of internal components of civil power generation facilities, specifically, it relates to a welding method and welding fixture for a double-hole tube for a control rod guide tube. Background Technology

[0002] Vacuum electron beam welding, a widely used welding method, features low heat input, minimal welding deformation, clean welds, and no oxidation, making it suitable for welding materials such as stainless steel and alloy steel. The control rod guide tube, a key component of a pressurized water reactor, has a complex structure and requires high precision. The double-hole tube, a core component of the continuous section of the lower control rod guide tube assembly, cannot be machined as a single unit due to its internal grooved structure. It is typically constructed by butt-welding two parts with double half-holes (hereinafter referred to as double-hole tube parts) together. The double-hole tube part assembly requires high precision. Taking a 90° double-hole tube part assembly as an example, the parallelism requirement on both sides is 0.1mm, the positional accuracy of the two holes is 0.1mm, the thickness of the double-hole tube is 18.80 (0, +0.04)mm, and the opening size at the open end is 6.3 (0, +0.3)mm. See attached figure for details. Figure 1 .

[0003] Traditional argon arc welding for butt welding of double-hole pipes results in significant deformation, making it impossible to meet the dimensional accuracy requirements of the double-hole pipes. In particular, the double-hole pipe is 18.80mm thick with only a positive tolerance of 0.04mm, which requires virtually no deformation along the 552mm length of the double-hole pipe. In addition, due to welding deformation, the opening size and the positional accuracy of the two holes are prone to exceeding tolerances.

[0004] Patent document CN114211205A discloses a manufacturing process for an integral double-hole tube of a control rod guide tube, relating to the technical field of manufacturing processes for control rod guide tubes in civilian nuclear power reactors. This manufacturing process includes a through-hole machining process and a through-slot machining process. The through-hole machining process involves using a CNC deep-hole drilling and boring machine, a custom-designed high-strength integral carbide internal cold gun drill to machine the through hole in one pass, and then grinding the inner surface of the machined through hole to a roughness of Ra1.6 and correcting its shape. The through-slot machining process involves designing a special fixture to ensure the straightness of the through slot, and using a machining center with a custom-designed high-strength extended end mill for segmented machining.

[0005] However, patent document CN114211205A only applies to the manufacture of relatively simple double-hole tubes using CNC machining equipment.

[0006] To mass-produce double-hole tubes with complex internal structures, a specialized anti-deformation tooling is used in conjunction with a vacuum electron beam welding method to perform electron beam welding on the double-hole tube parts. This method achieves dimensional compliance of the double-hole tube parts while improving manufacturing efficiency. Therefore, this invention designs a welding method and welding tooling for a control rod guide cylinder double-hole tube, solving the aforementioned problems. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide a welding method and welding fixture for a control rod guide tube with two holes.

[0008] A welding method for a control rod guide tube with two holes according to the present invention is characterized by the following steps:

[0009] Step S1: Wipe and clean the bevel of the double-hole tube part with a cleaning agent;

[0010] Step S2: Assemble the double-hole tube parts into the tooling. Multiple sets of double-hole tube parts are set up and fixed on the tooling with fixing nuts.

[0011] Step S3: Place the assembled double-hole tube parts into the vacuum chamber and evacuate the vacuum chamber;

[0012] Step S4: Electron beam spot welding positioning, spot weld one spot at each end of the workpiece, and evenly distribute the spot welds in the middle;

[0013] Step S5: Perform single-pass electron beam penetration welding;

[0014] Step S6: Welding completed, vacuum chamber vented, tooling with assembled double-hole tube parts removed;

[0015] Step S7: Remove the retaining nut and remove the double-hole tube component assembly from the fixture.

[0016] By adopting the above technical solution, multiple sets of double-hole tube component assemblies can be placed in the tooling to achieve high-quality mass production of double-hole tube component assemblies. Furthermore, an effective inspection system is formed through visual inspection of welds and liquid penetration. In addition, the tooling effectively reduces welding deformation, thereby increasing the precision of the produced parts. The use of vacuum electron beam welding effectively ensures the mass production of high-quality parts.

[0017] Preferably, in step S1: two double-hole tube parts are assembled into a double-hole tube part assembly.

[0018] Preferably, in step S4: during the uniform spot welding process, it is necessary to observe whether the electron beam spot is in the center of the weld. If the electron beam spot is not in the center of the weld, it is necessary to adjust the electron beam spot to be in the center of the weld.

[0019] Preferably, in step S5: before electron beam single-pass deep penetration welding, the electron beam gun head needs to pre-traverse the welding path to ensure that the entire weld seam is correctly aligned with the spot path; after electron beam single-pass deep penetration welding, whether to perform finishing welding should be selected according to the weld seam surface formation. If the weld seam formation is good, finishing welding is not performed; for double-hole tube weld seam penetration depth <1mm, the finishing welding parameters are consistent with the deep penetration welding parameters.

[0020] According to the present invention, a welding fixture for a control rod guide tube with two holes is provided, and a welding method for the control rod guide tube with two holes is provided. The fixture includes a fixture support, in which multiple sets of double-hole tube parts with embedded inner support round bars are arranged, and the double-hole tube parts abut against two adjacent sides of the fixture support. A gap is left between the two sides of the fixture support abutting side and the double-hole tube parts. The gap is filled with side pads and upper pads. A fixing nut is screwed to the outside of the fixture support, and the fixing nut abuts against and drives the side pads and upper pads to approach the double-hole tube parts.

[0021] By adopting the above technical solution and using shell-type clamping fixtures, double-hole tube parts can be assembled in batches with high welding efficiency. The fixture is assembled from detachable components such as fixture brackets, pads, and fixing nuts. The size of the fixture brackets and pads, as well as the number of nuts, can be adjusted according to actual needs. This fixture structure has a wide range of applications.

[0022] An assembly method for a welding fixture for a control rod guide tube with two holes, provided by the present invention, includes the following steps:

[0023] Step S1: Place the inner support rod into the slot at the open end of the double-hole tube part, and assemble the two double-hole tube parts.

[0024] Step S2: Arrange the double-hole tube parts with the assembled inner support rod neatly in the tooling bracket, and stack multiple of them;

[0025] Step S3: Install pads on top of the stacked double-hole tube parts assembly, and fill the sides with side pads A and B;

[0026] Step S4: Tighten the upper fixing nut to press the stacked double-hole tube parts; at the same time, tighten the left fixing nut to press the side pad A and side pad B against the double-hole tube parts, so that the weld surfaces of the paired double-hole tube parts are neat and flat.

[0027] By adopting the above technical solution, the problem of welding deformation of double-hole tube components is solved; the welding of double-hole tube components is successfully achieved, with good weld formation, small deformation of double-hole tube components, and the dimensions of double-hole tube components meet the requirements without the need for straightening; the internal and external support methods are combined to form a complete anti-deformation tooling with good anti-deformation effect.

[0028] Preferably, in step S1: the length of the inner support rod is the same as the length of the double-hole tube part and they are aligned.

[0029] Preferably, in step S2: the number of paired double-hole tube parts stacked is selected according to the tooling bracket size, which is selected by the vacuum chamber size of the vacuum electron beam welding machine.

[0030] Preferably, in step S3: the height of the upper pad is ≥10mm, and the width is 1 / 4 of the width of the double-hole tube component assembly.

[0031] Preferably, in step S3: the height of side pad A is consistent with the height of the double-hole tube component assembly, and the height of side pad B is half the height of the double-hole tube component assembly, that is, consistent with the height of a single double-hole tube component. The side pads are arranged in the following order from top to bottom: one side pad B, four side pads A, and one side pad B. The number of rows / columns of nuts on the upper and left sides is determined according to the length of the double-hole tube. The spacing between each row / column of nuts on the upper side is no more than 50mm, and the spacing between each row / column of nuts on the left side is no more than 100mm.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. Vacuum electron beam welding is adopted, which can meet the precision requirements of double-hole tube structures, with small welding deformation, good weld formation, and no need for post-weld machining.

[0034] 2. Vacuum electron beam welding is adopted, along with special tooling, for single-pass forming, which improves welding efficiency and enables high-volume manufacturing of double-hole tube parts and assemblies.

[0035] 3. Compared to integral machining manufacturing processes, vacuum electron beam welding is suitable for manufacturing double-hole tube parts and assemblies with complex internal structures. Attached Figure Description

[0036] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0037] Figure 1 This is a schematic diagram of the double-hole tube component assembly of the present invention.

[0038] Figure 2 This is a schematic diagram of the anti-deformation tooling for the dual-hole tube component assembly of the present invention.

[0039] Figure 3 This is a schematic diagram of the double-hole tube component of the present invention.

[0040] Figure 4 This is a schematic diagram of the welding of the double-hole tube component assembly of the present invention.

[0041] The figure shows: 1. Tooling bracket; 2. Upper pad; 3. Double-hole tube part; 4. Fixing nut; 5. Side pad A; 6. Side pad B; 7. Inner support round bar. Detailed Implementation

[0042] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0043] A welding method and welding fixture for a control rod guide tube with two holes, including: taking vacuum electron beam welding of a 90° double-hole tube as an example, the 90° double-hole tube component consists of three parts as shown in the appendix. Figure 1 90° double-hole tube parts 3 (see attachment) Figure 3 The welding diagram is attached. Figure 4 The component to be welded is grade Z2CN19-10 (nitrogen controlled), requiring a penetration depth ≥ 0.76mm. The welding process for the double-hole pipe component 3 is as follows:

[0044] Step S1: Wipe and clean the bevel of the double-hole tube part 3 with acetone; assemble two double-hole tube parts 3 into a double-hole tube part 3 assembly.

[0045] Step S2: Assemble the double-hole tube parts 3 into the tooling in groups of 5, and secure them firmly to the tooling using the fixing nuts 4.

[0046] Step S3: Place the assembled double-hole tube part 3 into the vacuum chamber and evacuate to 5×10-4MPa.

[0047] Step S4: Electron beam spot welding positioning, spot weld one weld point at each end of the weldment, and evenly distribute 6 weld points in the middle, with a weld point interval of about 79mm.

[0048] Step S5: Electron beam single-pass penetration welding requires strict welding parameters to ensure penetration depth ≥ 0.76mm.

[0049] Step S6: Welding completed, vacuum chamber vented, tooling of assembled double-hole tube part 3 removed.

[0050] Step S7: Remove the fixing nut 4 and remove the double-hole tube part 3 assembly from the tooling.

[0051] Preferably, in step S4: during the uniform spot welding process, the welding operator needs to observe whether the electron beam spot is in the center of the weld. If the electron beam spot is not in the center of the weld, it needs to be adjusted to be in the center of the weld. This process serves the purpose of electron beam positioning and alignment with the weld.

[0052] Preferably, in step S5: before single-pass deep penetration welding with electron beam, the electron beam gun head needs to pre-traverse the welding path to ensure that the entire weld seam is correctly aligned with the spot path; the welding parameters are: spot welding: electron beam current 8mA, electron gun voltage 39KV, focusing current 1.80A; deep penetration welding: electron beam current 20mA, electron gun voltage 39KV, welding speed 100cm / min, focusing current 1.77A, to achieve the required penetration depth ≥0.76mm;

[0053] Before and after electron beam single-pass deep penetration welding, if the weld formation is good, no finishing welding is required; if the weld surface fails visual inspection, electron beam single-pass finishing welding is required. The finishing welding parameters are: electron beam current 20mA, electron gun voltage 39KV, welding speed 100cm / min, focusing current 1.77A, which are consistent with the deep penetration welding parameters.

[0054] Using this tooling and vacuum electron beam welding method, the weld seam passed visual inspection and liquid penetration test, and the weld formation was good and without defects. In addition, the tooling effectively reduced welding deformation, and the dimensions of the three components of the double-hole tube part passed the inspection after welding, so no straightening was required.

[0055] This embodiment also provides a welding fixture for a double-hole tube guide tube of a control rod, used to limit the double-hole tube in the welding method of the double-hole tube guide tube of the control rod: it includes a fixture bracket 1, in which multiple sets of double-hole tube parts 3 with embedded inner support round bars 7 are arranged, and the double-hole tube parts 3 abut against two adjacent sides of the fixture bracket 1, with gaps between the two sides of the fixture bracket 1 abutting side and the double-hole tube parts 3; the gaps are filled with side pads 5 and upper pads 2, and a fixing nut 4 is screwed to the outside of the fixture bracket 1, the fixing nut 4 abuts against and drives the side pads and upper pads 2 to approach the double-hole tube parts 3.

[0056] In vacuum electron beam welding, a shell-type clamping fixture is used to assemble double-hole tube parts 3 in batches, resulting in high welding efficiency. The originality of the anti-deformation fixture installation is that the inner support round bar 7 matches the round hole at the opening end of the double-hole tube, and then the whole is placed in the fixture bracket 1. The pad and fixing nut 4 are used to achieve the purpose of anti-deformation. The fixture is assembled by detachable parts such as fixture bracket 1, pad, and fixing nut 4. The size of fixture bracket 1, pad, and nut arrangement can be adjusted according to actual needs. The fixture structure has a wide range of applications. It not only effectively reduces welding deformation, but also allows for batch assembly of double-hole tube parts (3) and overall vacuuming, avoiding vacuuming each welded part and shortening the welding cycle. The size of fixture bracket 1 is determined according to the size of the vacuum chamber, and the size of pad and the number of nuts are determined according to the size of the double-hole tube parts (3). It has a certain degree of flexibility in actual use.

[0057] This embodiment also provides an assembly method for a welding fixture for a control rod guide tube with two holes. The assembly process of the welding fixture and the two-hole tube for the control rod guide tube with two holes is as follows:

[0058] Step S1: First, place the inner support rod 7 into the slot at the open end of the double-hole tube part 3, and assemble the two double-hole tube parts.

[0059] Step S2: Then, arrange the double-hole tube parts 3, which have been assembled with the inner support rod 7, neatly in the tooling bracket 1, stacking 5 of them.

[0060] Step S3: Install pad 2 on top of the stacked double-hole tube parts 3, and fill the sides with side pad A5 and side pad B6.

[0061] Step S4: Tighten the upper fixing nut 4 to press the stacked double-hole tube parts 3; at the same time, tighten the left fixing nut 4 to press the side pad A5, side pad B6 and double-hole tube parts 3, and make sure that the weld surface (P direction) of the paired double-hole tube parts 3 is neat and flat.

[0062] Preferably, in step S1: the inner support rod 7 should be made according to the hole diameter of the double-hole tube part 3, with a diameter of φ11.16(-0.05,0)mm and a length consistent with the length of the double-hole tube part 3, which is 552mm.

[0063] Preferably, in step S3: the height of the middle side upper pad 2 is 10mm, and the width is 1 / 4 of the width of the double-hole tube part 3 assembly, which is 15.5mm.

[0064] Preferably, in step S3: the height of the middle side pad 5 is the same as the height of the double-hole tube component 3, which is 19mm, and the height of the side pad 6 is half the height of the double-hole tube component 3, which is 9.5mm. The side pads are arranged in the following order from top to bottom: one side pad B6, four side pads A5, and one side pad B6.

[0065] There are 4 fixing nuts 4 per row on the upper side and 5 fixing nuts 4 per column on the left side, according to... Figure 2 The nuts are evenly distributed; the upper side has 13 rows of 4 fixing nuts, with each row of 4 fixing nuts spaced approximately 46mm apart, and the left side has 7 columns of 4 fixing nuts, with each column of 4 fixing nuts spaced approximately 92mm apart.

[0066] The upper fixing nuts are arranged more densely because the double-hole tube is more prone to deformation along its length, making it difficult to meet the requirement of 0.1mm parallelism on both sides. The dense upper fixing nuts are used to ensure reliable anti-deformation effect along the length of the double-hole tube parts.

[0067] Preferably, in step S4, the dimensions and thicknesses of side pads A and B are designed to offset the gap between the pads from the gap in the double-hole tube component assembly. This prevents the double-hole tube component assembly from shifting due to stress when the pads are aligned, thus facilitating alignment. Additionally, the left-side fixing nut must be positioned at the gap between the two pads. This ensures that after the nut is fully fixed, each pad experiences more even stress, promoting force balance and further guaranteeing alignment of the double-hole tube component assembly.

[0068] By employing a specialized anti-deformation tooling and a vacuum electron beam welding method, the problem of welding deformation in the three-component double-hole tube part was solved. The welding of the three-component double-hole tube part was successfully achieved, with good weld formation, minimal deformation, and the dimensions of the three-component double-hole tube part meeting the requirements without the need for straightening. The internal and external supports were combined to form a complete anti-deformation tooling with good anti-deformation effect.

[0069] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0070] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A welding method for a double-hole tube guide cylinder for a control rod, characterized in that the steps include... include: Step S1: Wipe and clean the bevel of the double-hole tube part (3) with a cleaning agent; Step S2: Assemble the double-hole tube parts (3) into the tooling. Multiple sets of double-hole tube parts (3) are set up and fixed on the tooling by fixing nuts (4). Step S3: Place the assembled double-hole tube part (3) into the vacuum chamber and evacuate the vacuum chamber; Step S4: Electron beam spot welding positioning, spot weld one spot at each end of the workpiece, and evenly distribute the spot welds in the middle; Step S5: Perform single-pass electron beam penetration welding; Step S6: Welding completed, vacuum chamber vented, tooling for assembled double-hole tube part (3) removed; Step S7: Remove the fixing nut (4) and remove the double-hole tube part (3) assembly from the tooling; The assembly method for tooling includes the following steps: Step A: Place the inner support rod (7) into the slot at the open end of the double-hole tube part (3) and assemble the two double-hole tube parts (3); Step B: Arrange the double-hole tube parts (3) with the assembled inner support round bar (7) neatly in the tooling bracket (1) and stack them in multiple layers; Step C: Install pad (2) on top of the stacked double-hole tube parts (3) assembly, and fill the sides with side pad A (5) and side pad B (6); Step D: Tighten the upper fixing nut (4) to press the stacked double-hole tube parts (3); at the same time, tighten the left fixing nut (4) to press the side pad A (5) and side pad B (6) to press the double-hole tube parts (3), and the weld surfaces of the paired double-hole tube parts (3) are neat and flat. The fixture includes a fixture bracket (1), in which multiple sets of double-hole tube parts (3) with embedded inner support round bars (7) are arranged. The double-hole tube parts (3) abut against two adjacent sides of the fixture bracket (1), and there is a gap between the two sides of the fixture bracket (1) and the double-hole tube parts (3). The gap is filled with side pads and upper pads (2). A fixing nut (4) is screwed to the outside of the fixture bracket (1). The fixing nut (4) abuts against and drives the side pads A (5), B (6) and the upper pads (2) to approach the double-hole tube parts (3).

2. The welding method for the double-hole tube guide cylinder of the control rod according to claim 1, characterized in that, In step S1: two double-hole tube parts (3) are assembled into a double-hole tube part (3) assembly, which is applicable to double-hole tube parts with complex internal structures.

3. The welding method for the double-hole tube guide cylinder of the control rod according to claim 1, characterized in that, In step S4: During the uniform spot welding process, it is necessary to observe whether the electron beam spot is in the center of the weld. If the electron beam spot is not in the center of the weld, it is necessary to adjust the electron beam spot to be in the center of the weld.

4. The welding method for the double-hole tube guide cylinder of the control rod according to claim 1, characterized in that, In step S5: Before electron beam single-pass deep penetration welding, the electron beam gun head needs to pre-traverse the welding path to ensure that the entire weld seam is correctly aligned with the spot path; after electron beam single-pass deep penetration welding, depending on the weld seam surface formation, whether to perform finishing welding should be selected. If the weld seam formation is good, finishing welding is not performed; for double-hole tube weld seam penetration depth <1mm, the finishing welding parameters are the same as the deep penetration welding parameters.

5. The welding method for the double-hole tube of the control rod guide cylinder according to claim 1, characterized in that, In step A: the length of the inner support round bar (7) is consistent with the length of the double-hole tube part (3) and they are aligned.

6. The welding method for the double-hole tube of the control rod guide cylinder according to claim 1, characterized in that, In step B: the number of pairs of double-hole tube parts (3) stacked is selected according to the size of the tooling bracket (1), and the size of the tooling bracket (1) is selected by the size of the vacuum chamber of the vacuum electron beam welding machine.

7. The welding method for the double-hole tube guide cylinder of the control rod according to claim 1, characterized in that, In step C: the height of the upper pad (2) is ≥10mm and the width is 1 / 4 of the width of the double-hole tube part (3) assembly.

8. The welding method for the double-hole tube of the control rod guide cylinder according to claim 1, characterized in that, In step C: the height of side pad A (5) is consistent with the height of the double-hole tube component (3) assembly, and the height of side pad B (6) is half the height of the double-hole tube component (3) assembly, that is, consistent with the height of a single double-hole tube component (3). The side pads are arranged in the following order from top to bottom: one side pad B (6), four side pads A (5), and one side pad B (6). The number of rows / columns of nuts on the upper and left sides is determined according to the length of the double-hole tube. The spacing between each row / column of nuts on the upper side (4) is no more than 50mm, and the spacing between each row / column of nuts on the left side (4) is no more than 100mm.

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