Diamond composite punch assembly

Abstract

The utility model belongs to the technical field of nuclear fuel pellet preparation, and particularly relates to a diamond composite punch assembly. Comprising an upper punch, a female die and a lower punch, the female die is of a columnar structure with a hollow structure, an upper punch and a lower punch are arranged at the two ends of the hollow structure of the female die respectively, and a fuel pellet blank is clamped between the upper punch and the lower punch. The fuel pellet forming mold has the beneficial effects that the forming pressure and the demolding pressure of a fuel pellet are lower. And the forming work of the fuel pellet can be completed at lower power consumption. The forming temperature is low, and due to the fact that the diamond has smaller friction force, less heat is generated in the fuel pellet forming process. And the condition of material surface oxidation caused by high temperature is avoided. And the service life is long, and diamond has higher strength, hardness and wear resistance. And the service life is longer. And therefore, the economic use cost is lower.

Description

Technical Field

[0001] The utility model belongs to the technical field of nuclear fuel pellet preparation, and in particular relates to a diamond composite punch assembly. Background Art

[0002] As a nuclear fuel, nuclear fuel pellets have the advantages of high melting point, good high temperature stability, and stable chemical properties, and have been widely used in the field of nuclear fuel. The manufacturing process of nuclear fuel pellets adopts powder metallurgy technology, and the finished nuclear fuel pellets are manufactured through processes such as powder mixing, batching, roller granulation, spheroidization, molding, sintering, and grinding. Among them, powder molding is a very important process. The powder is solidified by bidirectional pressure to obtain the required pellet green body. The combination of the punch and the female mold of the molding equipment is the material that directly contacts the nuclear fuel powder. The physical and mechanical properties of the punch and the female mold have a direct impact on the quality of the nuclear fuel green body. The currently widely used cemented carbide punches and molds have problems such as short life, high friction, and high molding temperature. Utility Model Content

[0003] The utility model aims to provide a diamond composite punch assembly, which can solve the problems of high forming pressure, high forming temperature and poor forming effect when a hard alloy punch is used for bidirectional pressurizing forming of nuclear fuel pellets.

[0004] The technical solution of the utility model is as follows: a diamond composite punch assembly, comprising an upper punch, a female die and a lower punch; the female die is a columnar structure with a hollow structure, and the upper punch and the lower punch are respectively arranged at both ends of the hollow structure of the female die, and the fuel core block blank is sandwiched between the upper punch and the lower punch.

[0005] The upper punch, the female die and the lower punch are all made of diamond material.

[0006] The upper punch, the female die and the lower punch all comprise a diamond layer and a hard alloy layer.

[0007] The diamond layer is made of polycrystalline diamond, single crystal diamond, or CVD coated diamond layer.

[0008] The surface thickness of the diamond layer of the upper punch and the lower punch is ≥1mm, the diameter of the diamond layer of the end surface of the upper punch and the lower punch is 5-20mm, and the end surface is a three-dimensional shape.

[0009] The diamond layer thickness of the female mold is 0.2-2 mm, the inner diameter of the diamond is 5-20 mm, and the inner hole of the diamond is in a trumpet shape with an inclination of 0.4:100-1:100 on the side close to the upper punch.

[0010] The diamond layer end surfaces of the upper punch and the lower punch are planar structures.

[0011] The upper punch and the lower punch are hollow cylindrical, the diamond end faces are flat, and the diameter of the middle hole is 0.5-2 mm.

[0012] The female mold is a columnar structure with a hollow structure, and the hollow inner layer is a diamond layer.

[0013] The outer surface of the female mold columnar structure is provided with an annular V-shaped groove for limiting positioning.

[0014] The utility model has the following beneficial effects: the fuel pellet molding pressure and demoulding pressure are lower. The fuel pellet molding work can be completed at a lower power consumption. The molding temperature is low. Since diamond has a smaller friction force, the heat generated in the fuel pellet molding process is less. The surface oxidation of the material caused by high temperature is avoided. The service life is long. Since diamond has higher strength, hardness and wear resistance, it has a longer service life. Therefore, it also has a lower economic use cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a diamond composite punch assembly provided by the utility model;

[0016] Figure 2 Schematic diagram of the upper punch;

[0017] Figure 3 is a schematic cross-sectional view of the upper punch;

[0018] Figure 4 for Figure 3 The enlarged view of the J part in FIG.

[0019] Figure 5 is a schematic cross-sectional view of the lower punch;

[0020] Figure 6 for Figure 5 The enlarged view of the J part in FIG.

[0021] Figure 7 A cross-sectional schematic diagram of a diamond composite punch assembly provided by the utility model;

[0022] Figure 8 Schematic diagram of an upper punch with a flat end face;

[0023] Fig. 9 for Figure 8 The enlarged view of the J part in FIG.

[0024] Fig.10 It is a schematic diagram of an upper punch with a central control;

[0025] Fig.11 for Fig.10 Enlarged view of section J in .

[0026] In the figure: 1 upper punch, 2 female die, 3 fuel pellet blank, 4 lower punch. DETAILED DESCRIPTION

[0027] The utility model is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Diamond is a superhard material made by sintering diamond powder under high temperature and high pressure. In the 1970s, General Electric Company of the United States first synthesized diamond artificially, solving the problem of high price and scarcity of natural diamond. Diamond composite tool is a diamond composite material made by sintering diamond and cemented carbide and other materials into one. It has the bending strength and toughness of cemented carbide matrix, and the high hardness, high wear resistance and temperature resistance of diamond. Therefore, the composite diamond punch assembly composed of diamond and matrix can effectively improve the quality of fuel pellet molding, reduce molding problems and extend the service life of the mold.

[0029] The diamond is combined with the punch and the negative mold substrate, and is directly sintered and consolidated by the HPHT (high temperature and high pressure) method; or coated on the surface of the substrate by the CVD (vapor phase chemical deposition) method; or a single crystal diamond is cultivated by the CVD (vapor phase chemical deposition) method and then sintered and consolidated with the substrate by the HPHT (high temperature and high pressure) method to form a composite material diamond punch tool.

[0030] The points to be protected by the utility model are the key points such as the geometric structure of the diamond composite punch assembly and the three-dimensional shape of the diamond after the diamond and the matrix are combined.

[0031] like Figure 1 As shown, the utility model provides a diamond composite punch assembly, including an upper punch 1, a female die 2 and a lower punch 4; Figure 7 As shown, the female mold 2 is a columnar structure with a hollow structure, wherein the hollow inner layer is a diamond layer, and the diamond layer is covered with a cemented carbide layer. The outer surface of the columnar structure of the cemented carbide layer has an annular V-shaped groove for limiting. An upper punch 1 and a lower punch 4 are respectively provided at both ends of the hollow structure of the female mold 2, and the fuel core block blank 3 is sandwiched between the upper punch 1 and the lower punch 4, and the upper punch 1 and the lower punch 4 are both bolt-like structures.

[0032] The upper punch 1, the female die 2 and the lower punch 4 are all made of diamond material; the upper punch 1, the female die 2 and the lower punch 4 all include a diamond layer and a cemented carbide layer. The diamond layer can be made of polycrystalline diamond, single crystal diamond, CVD (chemical vapor deposition) coated diamond layer and other materials.

[0033] The surface thickness of the diamond layer of the upper punch 1 and the lower punch 4 is ≥1mm, the diameter of the diamond layer of the end face of the upper punch 1 and the lower punch 4 is 5~20mm, and the end face is a three-dimensional shape. The diamond layer thickness of the female mold 2 is 0.2~2mm, the inner diameter of the diamond is 5~20mm, and the inner hole of the diamond is close to the upper punch. The side is a trumpet shape with an inclination of 0.4:100~1:100.

[0034] In this embodiment, diamond can be used as the contact material with the nuclear fuel core, so that the friction during the core molding process is reduced. The purpose of extending the service life and reducing the cost is achieved. At the same time, in the first embodiment, the overall outer contour size is similar to that of the traditional cemented carbide punch die. It can be installed and replaced on the existing molding press, which greatly improves the interchangeability and reduces the cost.

[0035] like Figure 2-4 As shown, in the first embodiment, the punch end face is a three-dimensional curved surface structure, which can press out fuel pellets with dished and chamfered end faces.

[0036] Example 2: Figure 6 As shown, the diamond layer end surfaces of the upper punch 1 and the lower punch 4 are planar structures.

[0037] Example 3: Figure 7 As shown, the upper punch 1 and the lower punch 4 are hollow cylindrical, the diamond end faces are flat, and the diameter of the middle hole is 0.5-2 mm, which can form a nuclear fuel core with a middle hole.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that modifications to the technical solutions described in the aforementioned embodiments, or equivalent replacement of some or all of the technical features therein, do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A diamond composite punch assembly, characterized in that: It includes an upper punch, a female die and a lower punch; the female die is a columnar structure with a hollow structure, and the upper punch and the lower punch are respectively arranged at both ends of the hollow structure of the female die, and the fuel core block blank is sandwiched between the upper punch and the lower punch.

2. A diamond composite punch assembly as claimed in claim 1, characterized in that: The upper punch, the female die and the lower punch are all made of diamond material.

3. A diamond composite punch assembly as claimed in claim 2, characterized in that: The upper punch, the female die and the lower punch all comprise a diamond layer and a hard alloy layer.

4. A diamond composite punch assembly as claimed in claim 3, characterized in that: The diamond layer is made of polycrystalline diamond, single crystal diamond, or CVD coated diamond layer.

5. A diamond composite punch assembly as claimed in claim 3, characterized in that: The surface thickness of the diamond layer of the upper punch and the lower punch is ≥1mm, the diameter of the diamond layer of the end surface of the upper punch and the lower punch is 5-20mm, and the end surface is a three-dimensional shape.

6. A diamond composite punch assembly as claimed in claim 3, characterized in that: The diamond layer thickness of the female mold is 0.2-2 mm, the inner diameter of the diamond is 5-20 mm, and the inner hole of the diamond is in a trumpet shape with an inclination of 0.4:100-1:100 on the side close to the upper punch.

7. A diamond composite punch assembly as claimed in claim 3, characterized in that: The diamond layer end faces of the upper punch and the lower punch are planar structures.

8. A diamond composite punch assembly as claimed in claim 3, characterized in that: The upper punch and the lower punch are hollow cylindrical, the diamond end faces are flat, and the diameter of the middle hole is 0.5-2mm.

9. A diamond composite punch assembly as claimed in claim 1, characterized in that: The female mold is a columnar structure with a hollow structure, and the hollow inner layer is a diamond layer.

10. A diamond composite punch assembly as claimed in claim 9, characterized in that: The outer surface of the female mold columnar structure is provided with an annular V-shaped groove for limiting positioning.

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