Accurate positioning method for single-rod hole plugging welding end plug

Abstract

The invention belongs to the technical field of fuel rod helium filling hole plugging welding processes in the nuclear fuel element manufacturing process, and particularly relates to a method for accurately positioning a single rod hole plugging welding end plug. A large workpiece inlet and a small end plug outlet are formed in the two ends of the positioning tool respectively, the workpiece inlet and the end plug outlet are in conical surface transition, a workpiece enters from the workpiece inlet, the workpiece is positioned at the welding position through mechanical positioning of the internal structure of the positioning tool, and it is guaranteed that an end plug opening directly faces a tungsten electrode. According to the tool, the position, entering equipment, of a workpiece in the hole plugging welding process is mechanically positioned, the coaxiality of a welding seam and the tip end of a tungsten electrode is effectively guaranteed, and the tool plays a positive role in improving the subsequent welding quality and improving the safety in a fuel rod pile.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helium filling and hole plugging welding process in nuclear fuel element manufacturing process, and particularly relates to a method for accurately positioning a single-rod hole plugging and welding end plug. BACKGROUND

[0002] In the manufacturing process of nuclear fuel element fuel rods, fuel rod hole plugging and welding is often the last welding procedure in the production process, which plays a very important role in ensuring the sealing of the fuel rod interior and directly affects the product quality of the fuel rod and the safety thereof in the reactor. Since the existing welding equipment is not designed only for one product, a cylinder is used to push a baffle to make the workpiece enter the welding position reserved in the equipment and then welding is performed. However, it is found in process tests that the coaxiality of the end plug opening and the tungsten tip is poor, heat cannot uniformly cover the entire end face, and the experimental piece welded cannot meet the process requirements, so an accurate positioning tool is urgently needed to fix the position of the workpiece to ensure the coaxiality of the end plug opening and the tungsten tip, thereby improving the hole plugging and welding qualification rate. SUMMARY

[0003] The purpose of the application is to provide a method for accurately positioning a single-rod hole plugging and welding end plug. When performing single-rod hole plugging and welding operation, the end plug opening position needs to maintain high centering accuracy with the tungsten electrode. The application belongs to a workpiece positioning tool in hole plugging and welding of specific products, which is used to avoid the misalignment of the workpiece with the tungsten electrode after the workpiece enters the equipment and the welding crack, and effectively ensures the product qualification rate. In order to prevent the coaxiality of the end plug opening and the tungsten tip from being poor after the workpiece enters the welding equipment, affecting the welding quality and the performance of the weld, and reducing the in-reactor safety of the fuel rod, the tool mainly aims at the centering positioning of the workpiece in the hole plugging and welding process, so that the welding heat input energy is uniformly distributed on the workpiece end face, the qualification rate of the weld in the welding process is improved, and the in-reactor safety of the fuel rod is ensured.

[0004] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0005] A method for accurately positioning a single-rod hole plugging and welding end plug, the positioning tool has a larger workpiece inlet and a smaller end plug outlet at two ends, and the workpiece inlet and the end plug outlet are transitioned through a taper surface. The workpiece enters from the workpiece inlet, is positioned at the welding position by mechanical positioning of the internal structure of the positioning tool, and ensures that the end plug opening is directly opposite the tungsten electrode.

[0006] The positioning tool is designed in one piece.

[0007] The length of the end plug extending out of the positioning tool is not more than 2 mm.

[0008] The positioning tool is made of brass.

[0009] The application has the following beneficial effects:

[0010] The tool involved in the hole plugging welding process mechanically positions the position of the workpiece into the inside of the equipment, effectively ensures the coaxiality of the weld and the tungsten tip, and has a positive effect on improving the subsequent welding quality and improving the in-core safety of the fuel rod. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a schematic diagram of the device;

[0012] Figure 2 It is a schematic diagram of the device;

[0013] In the figure: 1 cladding tube; 2 positioning tool; 3 end plug; 4 tungsten electrode; 5 weld; 6 workpiece inlet; 7 end plug outlet. DETAILED DESCRIPTION

[0014] The present application will be described in detail below in combination with the drawings and specific examples.

[0015] As shown in Figure 1 , 2 , the positioning tool 2 is designed in one piece, with larger workpiece inlet 6 and smaller end plug outlet 7 at both ends, and the workpiece inlet 6 and the end plug outlet 7 are transitioned through a tapered surface. The workpiece enters from the workpiece inlet 6 and is mechanically positioned by the internal structure of the positioning tool 2 to position the workpiece at the welding position, ensuring that the end plug 3 opening is directly opposite the tungsten electrode 4, allowing the welding heat input to be evenly distributed on the surface of the end plug 3. The length of the end plug 3 extending out of the positioning tool 2 is adjusted according to the hole plugging depth requirement, and generally does not exceed 2mm to ensure cooling effect and positioning accuracy.

[0016] The stop block is designed in one piece, the workpiece enters from the inlet and directly fits with the profiled part, and is mechanically positioned by the internal structure of the tool to position the workpiece at the welding position, ensuring that the end plug opening is directly opposite the tungsten electrode, allowing the welding heat input to be evenly distributed on the surface of the end plug, and at the same time providing good cooling protection effect for the heat affected zone of the weld.

[0017] The positioning tool is designed according to the specific size of the workpiece and the internal structure of the equipment, discarding the traditional cylinder-driven baffle positioning method, improving the accuracy and convenience of on-site personnel operation; the fuel rod end plug material blocking device adopts a profiled design, which has a higher fit with the end plug, and can better ensure the coaxiality of the helium filling hole and the tungsten electrode during welding and positioning; according to the structural characteristics of different end plugs, the profiled part of the positioning tool is profiled in a specific shape, which can be applied to different shaped end plug hole plugging; the positioning block is made of brass or other materials with high specific heat and high thermal conductivity, which can effectively reduce the heating of the heat affected zone during welding, reducing the probability of overburning of stainless steel hole plugging welding.

Claims

1. A method for accurately positioning a single-rod hole-blocking welding end plug, characterized in that: The two ends of the positioning tool are respectively a larger workpiece inlet and a smaller end plug outlet. The workpiece inlet and the end plug outlet are transitioned by a conical surface. The workpiece enters through the workpiece inlet and is mechanically positioned by the internal structure of the positioning tool to position the workpiece in the welding position, ensuring that the end plug opening is facing the tungsten electrode.

2. The method for accurately positioning a single-rod hole-blocking welding end plug according to claim 1, characterized in that: The positioning tooling is an integrated design.

3. The method for accurately positioning a single-rod hole-blocking welding end plug according to claim 1, characterized in that: The length of the end plug extending from the positioning fixture shall not exceed 2 mm.

4. The method for accurately positioning a single-rod hole-blocking welding plug according to claim 1, characterized in that: The positioning tool is made of brass.

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