Hexagonal tube welding method for nuclear fuel assembly
By employing laser-argon arc hybrid welding technology and segmented trajectory programming, the problem of weld defects in the welding of hexagonal tubes for nuclear fuel assemblies was solved, achieving a high pass rate in welding.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA NORTH NUCLEAR FUEL CO LTD
- Filing Date
- 2021-12-31
- Publication Date
- 2026-07-14
AI Technical Summary
Existing argon arc welding and laser welding methods are prone to producing incomplete penetration or porosity defects when welding hexagonal tubes of nuclear fuel assemblies, making it difficult to meet the production requirements for high yield rates.
The laser-argon arc hybrid welding process, combined with segmented trajectory programming, utilizes the coordination of the laser beam and the argon arc welding torch, employing specific angles and positional relationships, along with the movement of the welding device, to optimize welding parameters and resolve weld defects.
It significantly improved the welding qualification rate, with the weld appearance inspection qualification rate reaching 100%, effectively reducing porosity and incomplete penetration defects, and meeting the weld appearance inspection requirements.
Smart Images
Figure CN116408546B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nuclear fuel welding technology, and specifically relates to a method for welding hexagonal tubes of nuclear fuel assemblies. Background Technology
[0002] In the manufacturing process of fuel assemblies, hexagonal tube welding is a crucial welding process. Current methods for welding hexagonal tubes in fuel assemblies employ argon arc welding or laser welding to meet requirements for weld penetration depth, minimal weld reinforcement, and a smooth appearance.
[0003] Argon arc welding or laser welding has certain limitations in the selection of welding parameters, and these two welding methods are prone to incomplete penetration or porosity defects during component production. When welding the corner sections, a large amount of energy from the welding torch is concentrated at the corners, resulting in an unsatisfactory weld appearance.
[0004] Process tests have shown that these two welding methods have a higher probability of producing defects when welding hexagonal tubes and are not suitable for the existing production model. Summary of the Invention
[0005] To address the above shortcomings, the purpose of this invention is to provide a method for welding hexagonal tubes in nuclear fuel assemblies, meeting the requirements for high yield rates in assembly production. This method introduces a laser-argon arc hybrid welding process and, in addition, in robot welding trajectory programming, a new segmented trajectory programming method is invented, effectively solving the problems of frequent porosity and incomplete penetration defects in the weld. Hexagonal tubes welded using this method achieve a better weld appearance, meeting the requirements for weld appearance inspection.
[0006] The technical solution of the present invention is as follows:
[0007] A method for welding hexagonal tubes of nuclear fuel assemblies, wherein the welding method adopts laser-argon arc composite welding process, the welding program adopts segmented trajectory programming, and the welding device and the assembly move simultaneously.
[0008] The laser welding uses a defocusing amount of +20.
[0009] The argon arc welding gun is at a 30° angle to the workpiece surface.
[0010] The tungsten needle is 4 ± 0.5 mm above the workpiece surface.
[0011] During welding, the laser beam is positioned slightly forward of the center of the argon arc molten pool.
[0012] When welding the flat surface of a hexagonal tube, a slow welding speed should be used to ensure the weld penetration depth.
[0013] The component rotates to the right, and the welding mechanism swings to the right around the weld point as the axis. During the rotation, the laser beam is always perpendicular to the workpiece surface; at the same time, the welding mechanism moves forward along the direction of the hexagonal tube surface.
[0014] When welding the corner section of the hexagonal tube, a fast welding speed is used. When welding the corner, the welding mechanism swings in the opposite direction of the component rotation with the weld point as the axis. When the corner of the component rotates to the top, the laser beam rotates to a vertically downward angle.
[0015] The component continues to rotate to the right, while the welding mechanism continues to swing in the opposite direction of the component's rotation around the weld point until it passes the corner of the hexagonal tube.
[0016] The welding device changes its swing direction to the component's rotation direction, slowing down the welding speed and completing one welding cycle.
[0017] The beneficial effects of this invention are as follows:
[0018] This welding method significantly improves the pass rate of component welding. Common defects in component welds, such as porosity and incomplete penetration, are rarely seen with this method, and the weld surface appearance fully meets inspection requirements. Components produced using this welding method have a 100% pass rate for X-ray and metallographic inspections of the welds. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the welding method of the present invention;
[0020] Figure 2 This is a schematic diagram of the welding process of the present invention; Detailed Implementation
[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0022] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] A method for welding hexagonal tubes in nuclear fuel assemblies is disclosed. This method employs a laser-argon arc welding process, with the laser welding using a defocusing depth of +20°. The argon arc welding torch is positioned at a 30° angle to the workpiece surface, and the tungsten needle is positioned 4 ± 0.5 mm above the workpiece surface.
[0024] During welding, the laser beam is positioned slightly forward of the center of the argon arc molten pool.
[0025] Due to the combined heat input of laser and argon arc, the current of the argon arc can be reduced to a value that has little impact on the appearance of the weld, while a larger weld penetration can be obtained when the laser beam hits the argon arc molten pool.
[0026] The welding program uses segmented trajectory programming, with the welding device and components moving simultaneously.
[0027] During welding, the welding mechanism moves and oscillates relative to the component as the component rotates.
[0028] (1) When welding the plane of the hexagonal tube, a slower welding speed should be used to ensure sufficient weld penetration.
[0029] (2) The component rotates to the right, and the welding mechanism swings to the right with the weld point as the axis. To ensure a good welding effect, the laser beam is always perpendicular to the workpiece surface during the rotation. At the same time, the welding mechanism moves forward along the direction of the hexagonal tube surface.
[0030] (3) When welding the corner parts of the hexagonal tube, a faster welding speed is used to avoid excessive heat input at the corner. When welding the corner, the welding mechanism swings in the opposite direction of the component rotation with the weld point as the axis. When the component rotates to the top of the corner, the laser beam rotates to a vertically downward angle.
[0031] (4) The component continues to rotate to the right, while the welding mechanism continues to swing in the opposite direction of the component rotation around the welding point until the hexagonal tube corner is welded.
[0032] (5) The welding mechanism changes the swing direction to the component rotation direction, slows down the welding speed, and completes one welding cycle.
[0033] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.
[0034] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0035] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
[0036] The accompanying drawings of the embodiments disclosed in this invention only involve the methods involved in the embodiments of this disclosure. Other methods can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this invention can be combined with each other.
[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for welding hexagonal tubes of nuclear fuel assemblies, wherein the welding method for the hexagonal tubes of fuel assemblies employs a laser-argon arc hybrid welding process, characterized in that: The welding program uses segmented trajectory programming, with the welding device and components moving simultaneously. When the component rotates to the right, the welding mechanism swings to the right around the weld point as the axis, and the laser beam remains perpendicular to the workpiece surface during the rotation. At the same time, the welding mechanism moves forward along the direction of the hexagonal tube surface. When welding the corner of the hexagonal tube, a fast welding speed is used. When welding the corner, the welding mechanism swings in the opposite direction of the component's rotation around the weld point as the axis. When the component's corner rotates to the top, the laser beam rotates to a vertically downward angle. The component continues to rotate to the right, while the welding mechanism continues to swing in the opposite direction of the component's rotation around the weld point until it passes the corner of the hexagonal tube.
2. The method for welding hexagonal tubes of nuclear fuel assemblies as described in claim 1, characterized in that: The laser-argon arc hybrid welding uses a defocusing amount of +20.
3. The method for welding hexagonal tubes of nuclear fuel assemblies as described in claim 1, characterized in that: The argon arc welding torch is at a 30° angle to the workpiece surface.
4. The method for welding hexagonal tubes of nuclear fuel assemblies as described in claim 1, characterized in that: The tungsten needle is 4 ± 0.5 mm above the workpiece surface.
5. The method for welding hexagonal tubes of nuclear fuel assemblies as described in claim 1, characterized in that: During welding, the laser beam is positioned slightly forward of the center of the argon arc molten pool.
6. The method for welding hexagonal tubes of nuclear fuel assemblies as described in claim 1, characterized in that: When welding the flat surface of a hexagonal tube, a slow welding speed should be used to ensure the weld penetration depth.
7. The method for welding hexagonal tubes of nuclear fuel assemblies as described in claim 1, characterized in that: The welding device changes its swing direction to the component's rotation direction, slowing down the welding speed and completing one welding cycle.