Processing method of molybdenum heat shield

Abstract

The invention relates to a processing method of a molybdenum heat shield, which comprises the following steps of: (1) engraving and milling a molybdenum plate to obtain a heat shield part with a required shape; (2) the heat shield part obtained in the step (1) is subjected to surface treatment, and a pretreated part is obtained; the surface treatment comprises heating and bending which are carried out in sequence; and (3) the pretreated part obtained in the step (2) is subjected to laser welding, and the molybdenum heat shield is obtained. According to the machining method, the springback phenomenon after the molybdenum sheet is bent can be effectively controlled, the precision of the part is improved, the structure is stable and not prone to deformation after welding, and the service life of the part is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of parts processing, and in particular to a processing method of a molybdenum heat insulation cover. Background Art

[0002] Molybdenum material has a high melting point, high strength, good electrical and thermal conductivity, and excellent corrosion resistance. It is widely used in aerospace, electronics, machinery and other fields to manufacture various precision parts.

[0003] During the processing of molybdenum heat shields, due to molybdenum's relatively large coefficient of thermal expansion, localized high temperatures during welding can cause thermal stress in the parts, leading to deformation. This deformation not only affects the dimensional accuracy of the parts but can also reduce the strength and reliability of the welded joints, making it difficult to ensure overall performance after welding, increasing manufacturing costs and production cycles.

[0004] Furthermore, molybdenum has a high yield strength. Once the external force is removed during bending, the material will rebound to a certain extent due to its elastic recovery properties. This makes it difficult to precisely control the dimensions of the bent part and achieve the required shape and dimensional accuracy. In applications requiring high precision, this post-bending rebound problem seriously affects product quality and assembly accuracy, leading to scrap and low production efficiency.

[0005] Therefore, providing a processing method for a molybdenum heat shield to solve the bending rebound and improve the welding stability is a technical problem that needs to be solved in the current field. Summary of the Invention

[0006] In response to the above problems, the purpose of the present invention is to provide a method for processing a molybdenum heat shield. Compared with the existing technology, the processing method provided by the present invention can effectively control the rebound phenomenon after the molybdenum sheet is bent, improve the precision of the parts, and the structure is stable after welding, not easy to deform, thereby extending the service life of the parts.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for processing a molybdenum heat shield, the method comprising the following steps:

[0009] (1) Carving and milling the molybdenum plate to obtain the heat shield parts of the required shape;

[0010] (2) performing surface treatment on the heat shield part obtained in step (1) to obtain a pre-treated part; the surface treatment comprises heating and bending performed in sequence;

[0011] (3) Laser welding the pretreated parts obtained in step (2) to obtain a molybdenum heat shield.

[0012] In the present invention, by engraving and milling, excess material can be removed according to the design drawings, so that the external dimensions and internal structure of the heat shield parts meet the design requirements, and the heat shield parts with specific shapes and sizes are obtained, providing a basis for subsequent processing and use; the hardness of the molybdenum plate is reduced and the toughness is increased through the heating step in the surface treatment, thereby improving its plastic deformation ability during the bending process and alleviating the rebound problem after bending; laser welding has the advantages of high energy density, fast welding speed, and small heat-affected zone, which can improve the welding bonding strength and bonding rate of the molybdenum heat shield, and prevent weld embrittlement and the generation of pores.

[0013] Preferably, the thickness of the molybdenum plate in step (1) is 0.4-0.6 mm, for example, it can be 0.4 mm, 0.42 mm, 0.44 mm, 0.46 mm, 0.48 mm, 0.5 mm, 0.52 mm, 0.54 mm, 0.56 mm, 0.58 mm or 0.6 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0014] Preferably, the speed of the engraving and milling in step (1) is 9000-11000 rpm, for example, it can be 9000 rpm, 9200 rpm, 9400 rpm, 9600 rpm, 9800 rpm, 10000 rpm, 10200 rpm, 10400 rpm, 10600 rpm, 10800 rpm or 11000 rpm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0015] Preferably, the surface treatment in step (2) further comprises: polishing the heat shield parts to remove surface impurities before heating.

[0016] Preferably, the sandpaper used for polishing includes 320# and / or 600# sandpaper.

[0017] In the present invention, it is preferred to use 320# and 600# to polish in sequence, and control the polishing precision from coarse to fine, thereby improving the polishing effect and making the surface smoother.

[0018] Preferably, the heating in step (2) includes heating the portion of the part to be bent.

[0019] Preferably, the heating temperature is 100-160°C, for example, it can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C or 160°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the heating method includes: using a handheld spray gun to heat the portion to be bent.

[0021] In the present invention, a spray gun is preferably used to heat the area to be bent. The heated molybdenum plate can more easily undergo plastic deformation during the bending process, preventing cracking. When the spray gun is removed, the bending process is also cooled, gradually fixing the bent shape during the cooling process, reducing the degree of angle rebound.

[0022] In the present invention, by optimally controlling the heating temperature within a specific range, the hardness of the molybdenum plate can be reduced while its toughness is increased, thereby improving its plastic deformation ability during the bending process. At the same time, excessive grain changes in the molybdenum plate are avoided, which prevents degradation of material properties due to overheating.

[0023] Preferably, the power of the laser welding in step (3) is 120-140 W, for example, it can be 120 W, 122 W, 124 W, 126 W, 128 W, 130 W, 132 W, 134 W, 136 W, 138 W or 140 W, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] In the present invention, the laser welding uses clean molybdenum wire with a diameter of 0.1-0.3 mm as an auxiliary material.

[0025] Preferably, the spot size of the laser welding is 40-60 μm, for example, it can be 40 μm, 42 μm, 44 μm, 46 μm, 48 μm, 50 μm, 52 μm, 54 μm, 56 μm, 58 μm or 60 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the welding speed of the laser welding is 7-9 mm / min, for example, it can be 7 mm / min, 7.2 mm / min, 7.4 mm / min, 7.6 mm / min, 7.8 mm / min, 8 mm / min, 8.2 mm / min, 8.4 mm / min, 8.6 mm / min, 8.8 mm / min or 9 mm / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the protective gas used in the laser welding includes argon.

[0028] Preferably, the argon flow rate of the laser welding is 4-6 L / min, for example, it can be 4 L / min, 4.2 L / min, 4.4 L / min, 4.6 L / min, 4.8 L / min, 5 L / min, 5.2 L / min, 5.4 L / min, 5.6 L / min, 5.8 L / min or 6 L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] In the present invention, by optimally controlling the laser welding power, spot size, welding speed, argon gas flow rate and other operating conditions, the welding strength can be improved, welding defects such as pores and cracks can be reduced, and the performance of the weld can be improved.

[0030] Preferably, the processing method further comprises step (4): sequentially cleaning, treating with isopropyl alcohol, baking and cooling the laser-welded molybdenum heat shield.

[0031] Preferably, the cleaning comprises ultrasonic cleaning, rinsing, spraying, hot water washing, spraying, high pressure rinsing, ultrasonic cleaning, spraying, ultrasonic cleaning, hot water washing, spraying and drying performed in sequence.

[0032] Preferably, the power of the ultrasonic cleaning is 60-70W, for example, 60W, 62W, 64W, 66W, 68W or 70W, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the water temperature for hot water washing is 60-70°C, for example, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the water pressure of the high-pressure flushing is 7-9 MPa, for example, it can be 7 MPa, 7.2 MPa, 7.5 MPa, 7.8 MPa, 8 MPa, 8.2 MPa, 8.5 MPa, 8.8 MPa or 9 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the isopropyl alcohol treatment in step (4) comprises wiping or soaking with isopropyl alcohol.

[0036] Preferably, the baking temperature in step (4) is 70-80°C, for example, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] As a preferred technical solution of the present invention, the processing method comprises the following steps:

[0038] (1) Carve and mill a molybdenum plate with a thickness of 0.4-0.6 mm at a rotation speed of 9000-11000 rpm to obtain a heat shield part of the desired shape;

[0039] (2) polishing the heat shield part obtained in step (1) to remove surface impurities, wherein the polishing uses sandpaper of types including 320# and / or 600#, and then heating the part to be bent with a handheld spray gun at a temperature of 100-160° C., and then bending to obtain a pretreated part;

[0040] (3) laser welding the pretreated parts obtained in step (2) under the conditions of a power of 120-140 W, a spot size of 40-60 μm, a welding speed of 7-9 mm / min, and an argon flow rate of 4-6 L / min to obtain a molybdenum heat shield;

[0041] (4) The laser-welded molybdenum heat shield is cleaned, then wiped or soaked with isopropyl alcohol, and then baked at 70-80° C. and then cooled to obtain a finished product.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The processing method provided by the present invention can effectively control the rebound phenomenon of the molybdenum sheet after bending by sequentially performing heating and bending, thereby improving the bending accuracy and shape stability, ensuring that the geometric shape of the heat shield meets the design requirements, and improving the assembly accuracy and product quality.

[0044] (2) The processing method provided by the present invention can improve the dimensional stability and bonding strength of the molybdenum heat shield after welding by optimizing the welding process, reduce deformation after welding, and ensure the service life of the molybdenum heat shield.

[0045] (3) Under optimal conditions, the processing method provided by the present invention can make the welding bonding strength of the molybdenum heat shield reach above 415 MPa, avoiding the rebound problem. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] Example 1

[0048] This embodiment provides a method for processing a molybdenum heat shield, the method comprising the following steps:

[0049] (1) Using a molybdenum plate with a specification of 400×100×0.5 mm as the raw material, the molybdenum plate with a thickness of 0.5 mm was engraved and milled at a rotation speed of 10,000 rpm to obtain a heat shield part of the desired shape;

[0050] (2) The heat shield part obtained in step (1) is polished with 320# and 600# sandpaper in sequence to remove surface impurities, and then the part to be bent is heated with a handheld spray gun at a temperature of 130°C, and then bent 90° to obtain a pretreated part;

[0051] (3) laser welding the pretreated parts obtained in step (2) under the conditions of a power of 130 W, a spot size of 50 μm, a welding speed of 8 mm / min, and an argon flow rate of 5 L / min to obtain a molybdenum heat shield;

[0052] (4) The molybdenum heat shield after laser welding is cleaned, and the cleaning includes ultrasonic cleaning, rinsing, spraying, hot water washing, spraying, high-pressure washing, ultrasonic cleaning, spraying, ultrasonic cleaning, hot water washing, spraying and drying in sequence. The power of the ultrasonic cleaning is 75W, the water temperature of the hot water washing is 65°C, and the water pressure of the high-pressure washing is 8MPa. It is then soaked in isopropyl alcohol, baked at 75°C, and cooled to obtain a finished product.

[0053] Example 2

[0054] This embodiment provides a method for processing a molybdenum heat shield, the method comprising the following steps:

[0055] (1) Using a molybdenum plate with a specification of 400×100×0.5 mm as the raw material, the molybdenum plate with a thickness of 0.5 mm was engraved and milled at a rotation speed of 9000 rpm to obtain the heat shield part of the required shape;

[0056] (2) The heat shield part obtained in step (1) is polished with 320# and 600# sandpaper to remove surface impurities, and then the part to be bent is heated with a handheld spray gun at a temperature of 100°C, and then bent 90° to obtain a pretreated part;

[0057] (3) laser welding the pretreated parts obtained in step (2) under the conditions of a power of 140 W, a spot size of 40 μm, a welding speed of 9 mm / min, and an argon flow rate of 4 L / min to obtain a molybdenum heat shield;

[0058] (4) The molybdenum heat shield after laser welding is cleaned, and the cleaning includes ultrasonic cleaning, rinsing, spraying, hot water washing, spraying, high-pressure washing, ultrasonic cleaning, spraying, ultrasonic cleaning, hot water washing, spraying and drying in sequence. The power of the ultrasonic cleaning is 75W, the water temperature of the hot water washing is 65°C, and the water pressure of the high-pressure washing is 8MPa. It is then soaked in isopropyl alcohol, baked at 80°C, and then cooled to obtain a finished product.

[0059] Example 3

[0060] This embodiment provides a method for processing a molybdenum heat shield, the method comprising the following steps:

[0061] (1) Using a molybdenum plate with a specification of 400×100×0.5 mm as the raw material, the molybdenum plate with a thickness of 0.5 mm was engraved and milled at a rotation speed of 10,000 rpm to obtain a heat shield part of the desired shape;

[0062] (2) The heat shield part obtained in step (1) is polished with 320# and 600# sandpaper in sequence to remove surface impurities, and then the part to be bent is heated with a handheld spray gun at a temperature of 160°C, and then bent 90° to obtain a pretreated part;

[0063] (3) laser welding the pretreated parts obtained in step (2) under the conditions of a power of 120 W, a spot size of 60 μm, a welding speed of 7 mm / min, and an argon flow rate of 6 L / min to obtain a molybdenum heat shield;

[0064] (4) The molybdenum heat shield after laser welding is cleaned, and the cleaning includes ultrasonic cleaning, rinsing, spraying, hot water washing, spraying, high-pressure washing, ultrasonic cleaning, spraying, ultrasonic cleaning, hot water washing, spraying and drying in sequence. The power of the ultrasonic cleaning is 75W, the water temperature of the hot water washing is 65°C, and the water pressure of the high-pressure washing is 8MPa. It is then soaked in isopropyl alcohol, baked at 70°C, and cooled to obtain a finished product.

[0065] Example 4

[0066] This embodiment provides a method for processing a molybdenum heat shield. The difference between the processing method and the method in embodiment 1 is that the heating temperature is 90°C.

[0067] Example 5

[0068] This embodiment provides a method for processing a molybdenum heat shield. The difference between the processing method and the method in embodiment 1 is that the heating temperature is 180°C.

[0069] Example 6

[0070] This embodiment provides a method for processing a molybdenum heat shield. The difference between the processing method and that of embodiment 1 is that the power of the laser welding is 100W.

[0071] Example 7

[0072] This embodiment provides a method for processing a molybdenum heat shield. The only difference between the processing method and that of Example 1 is that the power of the laser welding is 160W.

[0073] Comparative Example 1

[0074] This comparative example provides a method for processing a molybdenum heat shield, which differs from Example 1 only in that no heating is performed before bending.

[0075] The welding strength of the molybdenum heat shields prepared in Examples 1-7 and Comparative Example 1 was measured by a tensile test, and the results are shown in Table 1. After the molybdenum plate was bent 90°, the rebound angle of the molybdenum plate was measured. The rebound angle is the absolute value of the difference between the actual bending angle and 90°. The results are shown in Table 1.

[0076] Table 1

[0077]

[0078]

[0079] In Table 1, “ / ” indicates that the springback after bending was large and no subsequent laser welding was performed.

[0080] From the data in Table 1 we can see that:

[0081] (1) Under optimal conditions, the processing method provided by the present invention can make the welding bonding strength of the molybdenum heat shield reach above 415 MPa, avoiding the rebound problem.

[0082] (2) A comprehensive comparison of the data of Example 1 and Examples 4-5 shows that the present invention can avoid the problem of rebound after bending by preferably controlling the heating temperature so that the elastic modulus of the molybdenum plate does not change significantly due to the heating temperature being too low, and at the same time avoid the problem of over-softening of the molybdenum plate and weakening its ability to resist elastic recovery due to the heating temperature being too high. It can be seen that the present invention can further avoid the problem of rebound after bending by preferably controlling the heating temperature range.

[0083] (3) A comprehensive comparison of the data of Example 1 and Examples 7-8 shows that the present invention can avoid excessive power causing burn-through of materials or generating a large amount of spatter, which affects the welding quality, by preferentially controlling the power of laser welding. At the same time, it can avoid excessive power causing slow welding speed and difficulty in achieving the ideal penetration depth, resulting in insufficient welding melting and affecting the welding quality. It can be seen that the present invention can further improve the welding bond strength by preferentially controlling the power of laser welding.

[0084] In summary, the processing method provided by the present invention can effectively control the rebound phenomenon of the molybdenum sheet after bending, improve the precision of the parts, and the structure is stable after welding, not easy to deform, thereby extending the service life of the parts.

[0085] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for processing a molybdenum heat shield, characterized in that: The processing method comprises the following steps: (1) Carving and milling the molybdenum plate to obtain the heat shield parts of the required shape; (2) performing surface treatment on the heat shield part obtained in step (1) to obtain a pre-treated part; the surface treatment comprises heating and bending performed in sequence; (3) Laser welding the pretreated parts obtained in step (2) to obtain a molybdenum heat shield.

2. The processing method according to claim 1, characterized in that: The thickness of the molybdenum plate in step (1) is 0.4-0.6 mm.

3. The processing method according to claim 1 or 2, characterized in that: The rotation speed of the engraving and milling in step (1) is 9000-11000 rpm.

4. The processing method according to any one of claims 1 to 3, characterized in that: The surface treatment in step (2) further includes: polishing the heat shield parts to remove surface impurities before heating; Preferably, the sandpaper used for polishing includes 320# and / or 600# sandpaper.

5. The processing method according to any one of claims 1 to 4, characterized in that: The heating in step (2) includes heating the portion of the part to be bent; Preferably, the heating temperature is 100-160°C; Preferably, the heating method includes: using a handheld spray gun to heat the portion to be bent.

6. The processing method according to any one of claims 1 to 5, characterized in that: The power of the laser welding in step (3) is 120-140W; Preferably, the spot size of the laser welding is 40-60 μm; Preferably, the laser welding speed is 7-9 mm / min; Preferably, the protective gas used in the laser welding includes argon; Preferably, the argon gas flow rate of the laser welding is 4-6 L / min.

7. The processing method according to any one of claims 1 to 6, characterized in that: The processing method further comprises step (4): sequentially cleaning, treating with isopropyl alcohol, baking and cooling the laser-welded molybdenum heat shield.

8. The processing method according to claim 7, characterized in that: The isopropyl alcohol treatment in step (4) includes wiping or soaking with isopropyl alcohol.

9. The processing method according to claim 7 or 8, characterized in that: The baking temperature in step (4) is 70-80°C.

10. The processing method according to any one of claims 1 to 9, characterized in that: The processing method comprises the following steps: (1) Carve and mill a molybdenum plate with a thickness of 0.4-0.6 mm at a rotation speed of 9000-11000 rpm to obtain a heat shield part of the desired shape; (2) polishing the heat shield part obtained in step (1) to remove surface impurities, wherein the polishing uses sandpaper of types including 320# and / or 600#, and then heating the part to be bent with a handheld spray gun at a temperature of 100-160° C., and then bending to obtain a pretreated part; (3) laser welding the pretreated parts obtained in step (2) under the conditions of a power of 120-140 W, a spot size of 40-60 μm, a welding speed of 7-9 mm / min, and an argon flow rate of 4-6 L / min to obtain a molybdenum heat shield; (4) The laser-welded molybdenum heat shield is cleaned, then wiped or soaked with isopropyl alcohol, and then baked at 70-80° C. and then cooled to obtain a finished product.

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