Manufacturing method of multi-layer flat slot antenna

Abstract

The invention provides a manufacturing method of a multi-layer flat plate slot antenna, and the method carries out the size active avoidance in the processing of a single-layer flat plate cavity, thereby compensating the variation of the thickness of brazing filler metal after welding, and effectively improving the accuracy of the size of the cavity after welding. A method of equal-proportion amplification of a theoretical hollow shape is adopted in brazing filler metal processing, and a brazing filler metal flowing space is reserved, so that the phenomena of cavity surface pollution and accumulation caused by overflowing of redundant brazing filler metal in welding are effectively reduced; compared with a traditional scheme, the novel surface treatment, drying and protection method improves the welding surface quality and the working efficiency, the scheme can effectively improve the welding quality and the electrical performance of the multi-layer slot planar antenna, and has the advantages of being good in operability, high in reliability and the like.

Description

[0001] Technology

[0002] The invention relates to a method for manufacturing a multi-layer flat slot antenna, and belongs to the technical field of antenna processing and manufacturing. Background Art

[0003] Compared with other antennas, the flat slot antenna has the performance advantages of stable beam pointing, high radiation efficiency, low side lobes, large power capacity and high working efficiency. At the same time, it has the structural advantages of good rigidity and strength, light weight, low height, compact structure and high reliability. It is widely used in aerospace, satellite communications, missile radar and other systems.

[0004] The multi-layer flat slot antenna is generally divided into multiple separate flat structures such as the radiation layer, the feed layer, and the power division network layer. Each flat structure has a different hollow shape, and the multi-layer structure is combined in parallel to form a complex space cavity structure. At present, the manufacturing method of this type of antenna is mainly based on brazing, especially vacuum furnace brazing. Although brazing has the advantages of small welding deformation and suitable molding, it also has problems such as the processing accuracy of thin flat structures, positioning and overflow of needle materials, which restrict the performance of antenna products. In particular, with the rapid development of radar antennas towards high frequency bands, large bandwidths, and high performance, the new flat slot antennas have more layers, more complex structures, and higher precision requirements. Therefore, the process design and processing and manufacturing stages of multi-layer flat slot antennas face unprecedented challenges. Summary of the invention

[0005] In view of this, the present invention provides a method for manufacturing a multi-layer planar slot antenna, which improves the positioning accuracy of the solder and the accuracy of the cavity size, solves the problem of solder overflow during welding, and thus effectively improves the overall performance of the antenna.

[0006] In order to achieve the above object, the present invention provides a method for manufacturing a multi-layer planar slot antenna, which mainly includes the following steps and technical points:

[0007] Step 1: Decompose and process each single-layer structure according to the cavity structure and size:

[0008] According to the structural characteristics and specific dimensions of the cavity, each single layer of the multi-layer planar slot antenna is decomposed and subjected to high-precision CNC machining. The decomposed single-layer planar has half the size of the lateral cavity.

[0009] Furthermore, each single-layer flat plate structure is provided with positioning pin holes at the same position in a fixed diagonal position, so that the assembled multi-layer structure has an overall unified pin hole combination positioning structure.

[0010] Furthermore, for a single-layer structure that is combined with other single-layer structures to form a complete cavity, the cavity depth needs to be reduced by about 1 / 5 to 1 / 4 of the solder thickness during processing. During the subsequent welding process, the solder melts and flows, and its volume becomes smaller, so the thickness of the solder layer after melting will be lower than the thickness of the original solder; when processing the cavity structure on a single-layer flat plate, the cavity depth is thinned, which can effectively pre-compensate the solder thickness after welding, thereby improving the accuracy of the cavity height.

[0011] Furthermore, tenons are arranged around the cavity of the single-layer flat plate to limit the position of the solder, and the diameter of the tenons is φ1mm-φ2mm; the tenons are evenly arranged along the length direction of both sides of the cavity and are arranged near the bend of the solder, and the maximum spacing size of the tenons does not exceed 50mm; matching penetration holes of the tenons are arranged at corresponding positions of the single-layer flat plate on the other side of the combined cavity, and the matching clearance between the tenons and the penetration holes is 0.03-0.06mm.

[0012] Furthermore, the surface roughness of the contacting single-layer plates is set to 3.2μm, which should not be too high and should be lower than the surface roughness requirement inside the cavity. The surface roughness inside the cavity should be as high as possible, generally needing to be processed to 1.6μm or above. After demonstration and practice, the surface roughness of 3.2μm-6.3μm is more conducive to the creeping of the solder after melting and the connection strength of the brazing.

[0013] Step 2: Design the shape and size of the solder according to the shape and size of the single-layer flat hollow structure and process it:

[0014] The shape and size of the brazing filler metal is designed according to the shape and size of the single-layer flat plate structure, especially the characteristics of the hollowed-out space cavity, and the brazing filler metal is processed by high-precision CNC. The brazing filler metal structure must completely surround the parallel cavity shape. In order to improve the neatness and accuracy of the edges, the brazing filler metal cannot be processed by laser or water cutting, but by CNC processing. The processing must be carried out under the complete clamping of the stainless steel flat tooling on the upper and lower surfaces. The tooling must be pre-processed with a hollow structure so that only the brazing filler metal is processed during the processing without touching the tooling material. Multiple layers of brazing filler metal can be stacked together for processing and then selected for the best.

[0015] Furthermore, the hollow structure of the stainless steel flat tooling is a proportionally enlarged shape of the theoretical hollow shape of the solder, and the single-side expansion distance is 0.5-1mm;

[0016] Furthermore, the hollow structure of the solder after processing is a proportionally enlarged shape of the theoretical hollow shape of the solder, and the unilateral indentation distance of the material is about 50% of the thickness of the solder, which is generally selected as 0.02-0.03mm;

[0017] Furthermore, the tenon positioning hole and the positioning pin hole on the solder need to be processed at one time; the tenon positioning hole and the positioning pin hole are both small clearance fits;

[0018] Step 3: Use chemical cleaning method to treat the parts to be welded:

[0019] After processing, the parts are contaminated due to cutting fluid and other reasons. Chemical cleaning methods are required to remove various dirt and oxide films on the surface to prepare for subsequent vacuum welding. The chemical cleaning method is used to treat the parts to be welded, which mainly includes the following steps:

[0020] ① Use a degreasing agent to remove oil stains on the surface of parts; the degreasing agent can be selected from many mature commercial degreasing agent products;

[0021] ② Soak or rinse the parts in warm water at 50-65℃:

[0022] ③ Soak in a diluted HCL solution with a mass percentage concentration of 2.5-3.5% and a temperature of 50-65°C for 100 seconds ± 10 seconds. If an ultrasonic vibration device (bidirectional) is added on both sides of the flat part, soak for 50 seconds ± 10 seconds;

[0023] ④ Rinse the surface of parts with deionized water:

[0024] Step 4: Dry Ice Drying and Vacuum Sealing

[0025] Dry ice can quickly evaporate water vapor and effectively reduce the temperature, which can effectively prevent the re-generation of oxide film. After cleaning, the parts need to be quickly dried using dry ice. The dried parts are wrapped with non-woven fabric and sealed by vacuum storage bags.

[0026] Step 5: Vacuum brazing and inspection

[0027] The brazing material and each layer of flat plate parts are assembled into a whole, and the heat-resistant austenitic stainless steel plate and the pressure block are combined to load the furnace for brazing. The large number of tenons on the single-layer flat plate structure cooperate with the positioning holes of the brazing material to achieve accurate positioning of the brazing material; two pin holes with the same diagonal position are used between each layer of flat plates to ensure the position accuracy between the layers.

[0028] After welding, the finished parts are inspected for appearance, air tightness, solder penetration and electrical testing to determine product performance.

[0029] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0030] 1. The cavity processing height dimension avoidance method in this scheme compensates for the change in solder thickness after welding, effectively improving the accuracy of the cavity dimension after welding.

[0031] 2. The hollow structure after solder processing in this scheme is a method of proportionally reducing the theoretical hollow shape of the solder, which effectively reduces the phenomenon of cavity surface contamination and accumulation caused by excess solder overflow during welding.

[0032] 3. The parts surface treatment technology route and the method of dry ice drying aluminum brazing parts provided by this scheme are time-saving, efficient and effective.

[0033] 4. This solution can effectively improve the welding quality and electrical performance of multi-layer slot planar antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of structural decomposition of an embodiment of the present invention (6 layers);

[0036] Figure 3 The design shape of a single-layer flat plate structure according to an embodiment of the present invention;

[0037] Figure 4 The processing shape (tenon design) of the single-layer flat plate structure of the embodiment of the present invention;

[0038] Figure 5 Schematic diagram of processing of the single-layer solder (tenon hole and pin hole);

[0039] Figure 6 A schematic diagram of the position of the single-layer solder and the single-layer flat plate structure after assembly;

[0040] In the figure:

[0041] Multi-layer slot planar antenna 1, single-layer planar structure 2, positioning pin hole 2.1, positioning tenon 2.2, solder 3, solder pin hole 3.1, solder positioning hole 3.2, solder indentation distance 3.3; DETAILED DESCRIPTION

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments are briefly introduced below. The following specific implementations are described only to illustrate different aspects of the present invention and should not be understood as limiting the scope of the present invention. Obviously, the drawings described below are only some embodiments of the invention patent. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] The present invention provides a method for manufacturing a multi-layer planar slot antenna, which mainly includes the following steps and technical points:

[0044] Step 1: Decompose each single layer and process it according to the cavity structure and size:

[0045] According to the cavity design structure and size, each single-layer flat plate (2) of the multi-layer flat plate slot antenna (1) is decomposed and subjected to high-precision CNC machining.

[0046] Furthermore, each single-layer flat plate (2) after processing is fixed at the same diagonal position to form a positioning pin hole (2.1) with consistent processing requirements;

[0047] Furthermore, after processing, the cavity depth of each single-layer flat plate (2) is reduced by 0.01 mm compared to the theoretical value of 1 / 2 of the cavity depth;

[0048] Furthermore, a tenon (2.2) is arranged around the cavity of the single-layer plate to limit the solder, and the diameter of the tenon is φ1.5mm, and the diameter is φ1mm at some fine places; the maximum spacing between the tenons (2.2) does not exceed 50mm; a matching penetration hole for the tenon is processed at the corresponding position of the matching flat plate structure on the other side, and the matching clearance between the tenon and the entry hole is 0.05mm. The tenon (2.2) and the solder positioning hole (3.2) are clearance matched;

[0049] Furthermore, the surface roughness of the contacting surfaces between the single-layer flat plates is set to 3.2 μm, and the surface roughness of the inner surface of the cavity is set to 1.6 μm or above.

[0050] Step 2: Design the shape and size of the solder according to the shape and size of the single-layer flat hollow structure and process it:

[0051] The brazing material is not processed by laser or water jet cutting, but by CNC machining.

[0052] The brazing material (3) is subjected to high-speed CNC machining under the complete clamping of the upper and lower stainless steel flat tooling. In order to obtain a brazing material with a more accurate shape, three layers of brazing material are stacked and processed together, and the one with the smallest deformation is selected.

[0053] The stainless steel flat tooling is made of heat-resistant austenitic stainless steel, and the tooling is pre-processed into a shape that conforms to the hollow structure of the brazing material;

[0054] Furthermore, the hollow structure shape of the stainless steel flat tooling is a proportionally enlarged shape of the theoretical hollow shape of the solder, and the single-side enlargement distance is 0.5 mm; this size enables the tooling to reliably clamp the solder layer and process only the solder without touching the tooling material during processing;

[0055] Furthermore, the hollow structure of the solder (3) after processing is a proportionally reduced shape of the theoretical hollow shape of the solder, and the single-side indentation distance (3.3) is set to 0.03 mm. During the welding process, the solder melts and flows, and mainly flows to the reserved distance (3.3) instead of directly overflowing into the cavity;

[0056] Furthermore, the tenon positioning hole and the positioning pin hole (2.1) on the solder need to be processed at one time; the tenon positioning hole and the positioning pin hole are both small clearance fits;

[0057] Step 3: Use chemical cleaning method to treat the parts to be welded:

[0058] A chemical cleaning method is used to remove various dirt and oxide films on the surface of each layer of flat plate (2) parts, so as to prepare for subsequent vacuum welding.

[0059] The chemical cleaning method is used to treat the parts to be welded, which mainly includes the following steps:

[0060] ① Use a special aluminum alloy degreasing agent to remove oil stains on the surface of parts; the degreasing agent can be HH-133 series of Huihong Chemical or other mature commercial products;

[0061] ② Soak or rinse the parts in warm water at 50-65℃ to remove excess degreasing agent;

[0062] ③ Add an ultrasonic vibration device to a diluted HCL solution with a mass percentage concentration of 2.5-3.5% and a temperature of 50-65°C, soak the parts in it for about 50 seconds and then take them out;

[0063] ④ Rinse the surface of parts with deionized water;

[0064] Step 4: Dry Ice Drying and Vacuum Sealing

[0065] The parts are quickly dried using dry ice. The dried parts are wrapped in non-woven fabric and sealed in a vacuum storage bag.

[0066] Step 5: Vacuum brazing and inspection

[0067] The brazing material (3) and the parts of each layer of flat plate (2) are assembled into a whole, and the heat-resistant austenitic stainless steel plate and the pressing block are combined and loaded into a furnace for brazing. A large number of tenons 2.2 on the single-layer flat plate structure 2 cooperate with the positioning holes 3.2 of the brazing material to achieve accurate positioning of the brazing material 3; two pin holes 2.1 with the same diagonal position are used for positioning between each layer of flat plate 2, thereby ensuring the position accuracy between the layers 2.

[0068] Step 5: Post-weld inspection

[0069] The welded product (1) is subjected to appearance inspection, air tightness inspection, solderability inspection and electrical test to determine product performance.

[0070] In summary, the present invention provides a method for manufacturing a multi-layer flat slot antenna: the method performs active size avoidance in the processing of a single-layer flat cavity, thereby compensating for the change in solder thickness after welding, and effectively improving the accuracy of the cavity size after welding; the method adopts a proportional enlargement method of the theoretical hollow shape in solder processing, and reserves solder flow space, thereby effectively reducing the phenomenon of cavity surface contamination and accumulation caused by excess solder overflow during welding. Compared with the traditional solution, the solution can effectively improve the welding quality and electrical performance of the multi-layer slot flat antenna, and also has the advantages of good operability and high reliability.

[0071] It should be understood that the above description of the specific implementation methods of this patent is only an exemplary description listed to facilitate ordinary technicians in the field to understand the patent scheme, and does not imply that the scope of protection of this patent is limited to these individual examples. Ordinary technicians in this field can fully understand the technical scheme of this patent and, without any creative work, obtain more specific implementation methods by combining technical features, replacing some technical features, adding more technical features, etc. to the examples listed in this patent. All these specific implementation methods are within the scope of the claims of this patent. Therefore, these new specific implementation methods should also be within the scope of protection of this patent.

[0072] In addition, for the purpose of simplifying the description, this patent may not list some common specific implementation schemes, which are naturally conceivable to ordinary technicians in this field after understanding the technical solution of this patent. Obviously, these solutions should also be included in the scope of protection of this patent.

Claims

1. A method for manufacturing a multi-layer planar slot antenna, mainly comprising five steps: decomposing and processing a single layer according to the cavity structure and size, designing and processing solder according to the hollow shape and size of the planar plate, treating the parts to be welded by chemical cleaning method, dry ice drying and vacuum sealing, vacuum brazing and inspection, etc., characterized in that: During the processing, the cavity depth of each single-layer structure needs to be reduced by about 1 / 5 to 1 / 4 of the solder thickness. The shape of each layer of solder hollow structure is a proportionally enlarged shape of the solder theoretical hollow shape, and the single side is enlarged by 0.02-0.03mm.

2. The method for manufacturing a multi-layer planar slot antenna according to claim 1, characterized in that: Tenons for limiting the solder are arranged around the cavity of each single-layer flat plate structure, and the diameter of the tenons is φ1mm-φ2mm; the tenons are roughly evenly arranged along the length direction of both sides of the cavity: and are arranged near the bend of the solder, and the maximum spacing size of the tenons does not exceed 50mm; matching penetration holes for the tenons are arranged at the corresponding positions of the single-layer flat plates on the other side of the combined cavity, and the matching clearance between the tenons and the penetration holes is 0.03-0.06mm; the surface roughness of the contact between the flat plates is 3.2μm, and the surface roughness inside the cavity is 1.6μm or higher.

3. The method for manufacturing a multi-layer planar slot antenna according to claim 1, characterized in that: The processing of the solder needs to be carried out under the complete clamping of the stainless steel flat tooling on the upper and lower surfaces. The tooling needs to pre-process a hollow structure, and the shape of the hollow structure is a proportional enlargement of the theoretical hollow shape of the solder, and the single-side enlargement distance is 0.5-1mm.

4. The method for manufacturing a multi-layer planar slot antenna according to claim 1 is characterized in that: The process of treating the parts to be welded by chemical cleaning mainly includes the following steps: ① Use degreasing agent to remove oil; ② Soak or rinse the parts in warm water at 50-65℃; ③ Soak in a diluted HCL solution with a mass percentage concentration of 2.5-3.5% and a temperature of 50-65°C for 100 seconds ± 10 seconds. If an ultrasonic vibration device (bidirectional) is added on both sides of the flat part, soak for 50 seconds ± 10 seconds; ④ Rinse the surface of parts with deionized water.

5. The method for manufacturing a multi-layer planar slot antenna according to claim 1 is characterized in that: After cleaning, the parts must be quickly dried using dry ice. The dried parts are wrapped with non-woven fabric and sealed with a vacuum storage bag.

6. The method for manufacturing a multi-layer planar slot antenna according to claim 1 is characterized in that: The method for manufacturing a multi-layer planar slot antenna according to claim 1 is characterized in that: During the solder processing, the tenon positioning holes and positioning pin holes on the solder need to be processed at one time; the tenon positioning holes and positioning pin holes are matched with small gaps; multiple layers of solder can be stacked and processed together and the best one can be selected.

7. The method for manufacturing a multi-layer planar slot antenna according to claim 1 is characterized in that: The diagonal fixed positions of each single-layer flat plate structure are provided with consistent positioning pin holes, and the assembled multi-layer structure has an overall unified pin hole combination positioning structure.

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