A high-altitude balloon radar reflector and its manufacturing process

Abstract

The present invention discloses a high-altitude balloon radar reflector and its manufacturing process in the technical field of composite material products, including a composite material mounting plate. A number of circular embedded holes are provided on the composite material mounting plate, and square embedded parts are filled in the embedded holes. An array of reflection units is installed on the embedded parts. The present invention reduces the weight of the high-altitude balloon radar reflector, improves the accuracy, and reduces the cost.

Description

Technical Field

[0001] The present invention relates to the technical field of composite products, and particularly relates to a radar reflector. Background Art

[0002] A high-altitude balloon radar is a radar carried by a high-altitude balloon. This kind of radar can detect various small targets under the conditions of the enemy's implementation of electronic countermeasures, the target being coated with various coatings, and the ground objects having reflected clutter. The main technical indicators of the high-altitude balloon radar consider load, load power consumption, etc.

[0003] In the existing technology, the manufacturing process cycle of the high-altitude balloon radar reflector is long and the workload is cumbersome. It is heavy in weight, which affects the stay time of the high-altitude balloon. Reducing weight and increasing speed have become problems to be overcome. In addition, it should be considered that since the high-altitude balloon radar reflector belongs to the high-end equipment manufacturing industry, the accuracy of the reflector is an extremely important technical indicator of the high-altitude balloon radar. The main influencing factor of the accuracy is the installation accuracy of the array reflection units. The installation accuracy is mainly determined by the installation accuracy of the embedded parts. Therefore, the high-precision installation of the embedded parts is particularly important. Moreover, the installation plate is a flat plate structure with a large size. It is extremely difficult to ensure the accuracy of nearly 1200 array reflection units on such a large flat plate. Summary of the Invention

[0004] Aiming at the deficiencies in the existing technology, the present invention provides a high-altitude balloon radar reflector and its manufacturing process, which reduces the weight of the high-altitude balloon radar reflector, improves the accuracy, and reduces the cost.

[0005] The purpose of the present invention is achieved as follows: A high-altitude balloon radar reflector includes a composite material installation plate. A plurality of circular embedded holes are opened on the composite material installation plate, and square embedded parts are filled in the embedded holes. Array reflection units are installed on the embedded parts.

[0006] As a preferred technical solution of the high-altitude balloon radar reflector of the present invention, the embedded parts are made of polyether ether ketone material, and the installation plate is a sandwich structure with a foam layer inside and a composite material layer outside.

[0007] A manufacturing process of a high-altitude balloon radar reflector includes the following steps:

[0008] Step 1) Manufacture the installation plate. Lay prepreg, adhesive film, foam, adhesive film, and prepreg on the surface of the flat mold in sequence, and obtain the formed installation plate after curing;

[0009] Step 2) Perform primary machining. Machine the preset position to obtain the embedded holes;

[0010] Step 3) Perform embedded installation. Install the polyether ether ketone embedded parts into the embedded holes;

[0011] Step 4) Secondary machining: Perform machining on the PEEK embedded part and the mounting plate to obtain threaded holes and pin holes.

[0012] Step 5) Install the array reflector unit: Fix the array reflector unit on the PEEK embedded part by screws to obtain the final high-altitude balloon radar reflector.

[0013] As a preferred technical solution of the manufacturing process of a high-altitude balloon radar reflector according to the present invention, step 1) is specifically as follows: Lay prepreg on the surface of the flat mold, and then lay a film on the surface of the prepreg. Make a vacuum bag to pre-pump and compact the film and prepreg. After the pre-pumping is completed, remove the vacuum bag. At the same time, place PMI foam. The foam is laid by splicing, and the splicing part is connected with foaming glue. Then lay the upper film and prepreg, and make a vacuum bag to pre-pump and compact after laying.

[0014] As a preferred technical solution of the manufacturing process of a high-altitude balloon radar reflector according to the present invention, the primary machining in step 2) is specifically as follows: After ensuring that there are no internal quality and dimensional tolerance problems with the mounting plate, the CNC machine tool in the machining center locates with the horizontal and vertical sides according to the structural design drawings, and ensures the accuracy through the programmed procedure of the machine tool. Machine a round hole on the mounting plate as the embedded hole.

[0015] As a preferred technical solution of the manufacturing process of a high-altitude balloon radar reflector according to the present invention, step 3) is specifically as follows: First, protect the entire mounting plate with transparent tape, then clean the tape at all embedded hole positions, inject the prepared adhesive into the embedded holes, place the embedded parts, press the embedded parts to the bottom, scrape the overflowing adhesive flat, and when the adhesive is not completely dry, clean the surface and remove the excess glue to cure the adhesive at room temperature.

[0016] As a preferred technical solution of the manufacturing process of a high-altitude balloon radar reflector according to the present invention, a protection treatment is also performed after the secondary machining in step 4) and before installing the array reflector unit in step 5). Specifically, first clean the residues machined in the threaded holes. After cleaning, protect the pin holes and threaded holes with cylindrical pins and screws, and then brush the short-cut carbon fiber and epoxy resin glue on the flanging at the periphery of the mounting plate.

[0017] As a preferred technical solution of the manufacturing process of a high-altitude balloon radar reflector according to the present invention, after protecting the threaded holes and pin holes with screws and cylindrical pins, flame spraying aluminum is performed on the parts that need to be sprayed with aluminum, and the sprayed aluminum layer is protected with a sealing agent after spraying.

[0018] As a preferred technical solution of the manufacturing process of a high-altitude balloon radar reflector according to the present invention, the machined dimensions and internal quality of the mounting plate after aluminum spraying need to be detected, and it can be put into the transfer product library for subsequent assembly and use only after determining that there are no any problems.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The present invention shortens the process cycle, greatly reduces the weight, and ensures the accuracy of the reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0022] Figure 1 It is a schematic structural diagram of the mounting plate in the present invention.

[0023] Figure 2 It is a front view of the mounting plate in the present invention.

[0024] Figure 3 It is Figure 2 an enlarged view of part A in

[0025] Figure 4 It is a process flow chart for manufacturing in the present invention.

[0026] Figure 5 It is a physical diagram of the mounted mounting plate in the present invention.

[0027] Figure 6 It is a physical diagram of the mounting plate after the first machining in the present invention.

[0028] Figure 7 It is a physical diagram of the mounting plate during the process of installing the embedded part in the present invention.

[0029] Figure 8 It is a physical diagram of the mounting plate with the embedded part installed in the present invention.

[0030] Figure 9 It is a physical diagram of the mounting plate after the second machining in the present invention.

[0031] Figure 10 It is a physical diagram of the mounting plate for cleaning the residues in the holes in the present invention.

[0032] Figure 11 It is a physical diagram of the protected mounting plate in the present invention.

[0033] Among them, 100 is the mounting plate, 101 is the embedded hole, 102 is the pin hole, 200 is the embedded part, and 201 is the threaded hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] As Figures 1-3 shown, a high-altitude balloon radar reflector includes a composite material mounting plate 100. A plurality of circular embedded holes 101 are formed in the composite material mounting plate 100. Square embedded parts 200 are filled in the embedded holes 101. An array of reflection units (not shown in the figure, and mounting holes are marked and can be directly mounted during installation) are installed on the embedded parts 200. The embedded parts 200 are made of polyether ether ketone material. The mounting plate 100 is a sandwich structure, with a foam layer inside and a composite material layer outside.

[0036] Specifically, the mounting plate 100 is a carbon fiber-foam sandwich structure composite material. The overall size of the mounting plate 100 is approximately 7000mm×3000mm×10mm, and it is composed of inner and outer skins, a foam sandwich, and the embedded parts 200. The thickness of the upper and lower skins of the main body of the mounting plate 100 is 0.2mm, and a plain weave carbon fiber is laid at 45°. The middle sandwich is PMI foam with a thickness of 10mm.

[0037] It should be noted that the circular embedded holes 101 are convenient to process compared to squares. The square embedded parts 200 have greater resistance during secondary processing (i.e., when processing threaded holes 201 on the embedded parts 200), which can prevent the embedded parts 200 from rotating and further ensure accuracy. The embedded parts 200 made of PEEK (polyether ether ketone) material greatly reduce the overall weight.

[0038] As Figure 4 shown, a manufacturing process of a high-altitude balloon radar reflector includes the following steps:

[0039] Step 1) Manufacture the mounting plate 100. First, lay 1 layer of T300-3K prepreg on the surface of the flat mold, and then lay a layer of structural adhesive film on the prepreg to make a vacuum bag for pre-pumping and compacting the adhesive film and the prepreg. After the pre-pumping is completed, remove the vacuum bag, and at the same time place the PMI foam. Since the area of the mounting plate 100 is large, the foam needs to be spliced and laid, and the splicing part is connected with foaming glue. After the foam laying is completed, lay the upper adhesive film and prepreg, make a vacuum bag for pre-pumping and then cure in a hot press can. After demolding, the mounting plate 100 is obtained, as Figure 5 shown.

[0040] Step 2) First machining: After ensuring that there are no internal quality and dimensional tolerance issues with the mounting plate 100, the outer dimensions and hole precision of the mounting plate 100 are positioned by the horizontal and vertical sides using the two-dimensional and three-dimensional drawings of the structural design on the digital machine tool in the machining center. The precision is ensured through the programmed procedures of the machine tool. A Φ12 mm round hole is machined on the mounting plate 100 as the embedded hole 101, as Figure 6 shown.

[0041] Step 3) Embedding: During operation, first protect the entire mounting plate 100 with transparent tape, and then clean the tape at all the embedded holes 101; Inject the prepared adhesive into the embedded hole 101 with a syringe, and the injection depth is about 1 / 3 of the depth of the embedded hole 101. Put the embedded part 200 in and press it to the bottom, and scrape the overflowing adhesive flat with a blade, as Figure 7 shown; Wait until the next morning when the adhesive has not completely dried, clean the surface and remove the excess glue. To prevent the skin from bulging due to the expansion of the adhesive when heated, the adhesive is cured at room temperature to obtain the mounting plate 100 as Figure 8 shown.

[0042] Step 4) Second machining: After the embedding is completed, as Figure 9 shown, the mounting plate 100 is machined for the second time, and holes are drilled and tapped on the embedded part 200; In order to ensure the successful installation of the radar town and the good fit of the thread with the screw, multiple specimens were made for experiments, and finally the optimal machining plan was determined.

[0043] Step 5) Protection treatment: The machined thread holes 201 and pin holes 102 need to be protected; First, clean the residues in the holes; Stand the mounting plate 100 upright and fix it with a fixture, and blow out the debris in the holes with an air pump spray gun, as Figure 10 shown, cleaning the residues in the holes; After cleaning, protect the pin holes 102 and thread holes 201 with cylindrical pins and screws, as Figure 11 described, the protected mounting plate 100; Brush the short-cut carbon fiber and epoxy resin glue on the flanging around the mounting plate 100; After protecting the thread holes 201 and pin holes 102 with screws and cylindrical pins, flame spray aluminum on the parts that need to be sprayed with aluminum, and protect the sprayed aluminum layer with a sealing agent after spraying.

[0044] Step 6) Warehousing: The upper and lower panels after spraying aluminum need to be inspected for machining dimensions and internal quality. After ensuring that there are no problems, they can be put into the transfer product warehouse for subsequent assembly and use.

[0045] Step 7) Install the array reflector unit: Take out the stored mounting plate 100, and then install and fix the array reflector unit on the polyether ether ketone embedded part 200 with screws to obtain the final high-altitude balloon radar reflector.

[0046] The mounting plate is made of composite material and glass fiber that are resistant to electromagnetic wave detection. It has a small radar reflection surface and almost no radar echo and infrared characteristic signal, making it difficult to detect. Composite material and glass fiber cannot be directly drilled and locked, and can only be locked in the form of embedded parts 200. This is a new process structure for locking embedded parts 200. The present invention shortens the process cycle, reduces weight, and ensures array accuracy.

[0047] At present, the current process for radar reflectors carried by high-altitude balloons is composite materials. There are a large number of embedded parts 200 of high-altitude balloon radar reflectors, and the position and size requirements are relatively high. If direct embedding is adopted, it is difficult to control the deformation of the foam and the expansion of the foam during curing, and the position of the embedded parts 200 is easily offset. If the reflector is formed first and then the holes are machined to embed the embedded parts 200, the aluminum parts are machined one by one, and then positioned by tooling and cured in batches. There is a risk of misalignment between the tooling for a long time, and the entire embedding work takes a long time.

[0048] But accuracy consistency is one of the main specifications for radar reflectors carried by high-altitude balloons.

[0049] PEEK (polyetheretherketone) material is used instead of aluminum parts. After the radar reflector carried by the high-altitude balloon is machined with embedded holes 101, it can be directly embedded at one time without worrying about the misalignment of the holes. The holes are machined after the one-time embedding and molding, which saves curing time and improves the accuracy between each group of arrays. It can more accurately detect small targets with reflected clutter, shorten the production cycle, and improve production efficiency.

[0050] The PEEK-made locking embedded parts 200 are lighter and more practical, achieving a 50% weight reduction, extending the air retention time, and having less fatigue and corrosion effects.

[0051] Traditional embedded parts are made of aluminum, which is a metal material. Metal materials will expand due to temperature, resulting in incompatibility with composite parts. Composite materials solve the problem of incompatibility caused by thermal expansion between different materials, which affects life and performance requirements.

[0052] The above embodiments are only used to help understand the method and core idea of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A high-altitude balloon radar reflector, characterized in that, It includes a composite material mounting plate (100), on which a number of circular embedded holes (101) are provided. Square embedded parts (200) are filled in the embedded holes (101). After the embedding is completed, machining is carried out on the mounting plate (100), and drilling and tapping are carried out on the embedded parts (200). An array of reflection units is installed on the embedded parts (200). The embedded parts (200) are made of polyetheretherketone material. The mounting plate (100) is a sandwich structure, with a foam layer inside and a composite material layer outside.

2. The manufacturing process of a high-altitude balloon radar reflector as described in claim 1, characterized in that, It includes the following steps: Step 1) Fabricate the composite material mounting plate (100). Lay prepreg, adhesive film, foam, adhesive film, and prepreg on the surface of the flat mold in sequence, and obtain the formed mounting plate (100) after curing. Step 2) First machining. Carry out machining at the preset position to obtain the embedded holes (101). Step 3) Embedding installation. Install the polyetheretherketone embedded parts (200) into the embedded holes (101). Step 4) Second machining. Carry out machining on the polyetheretherketone embedded parts (200) and the mounting plate (100) to obtain threaded holes (201) and pin holes (102). Step 5) Install the array of reflection units. Install and fix the array of reflection units on the polyetheretherketone embedded parts (200) with screws to obtain the final high-altitude balloon radar reflector.

3. The manufacturing process of a high-altitude balloon radar reflector according to claim 2, characterized in that, Specifically, step 1) is as follows: Lay prepreg on the surface of the flat mold, and then lay adhesive film on the surface of the prepreg. Fabricate a vacuum bag to pre-pump and compact the adhesive film and prepreg. After the pre-pumping is completed, remove the vacuum bag. At the same time, place PMI foam. The foam is laid by splicing, and the splicing joints are connected with foaming glue. Then lay the upper layer of adhesive film and prepreg, and fabricate a vacuum bag to pre-pump and compact after laying.

4. The manufacturing process of a high-altitude balloon radar reflector according to claim 2, characterized in that, Specifically, step 2) of the first machining is as follows: After ensuring that there are no internal quality and dimensional tolerance problems with the mounting plate (100), the digital machine tool in the machining center positions with two horizontal and vertical sides according to the structural design drawings, and ensures the accuracy through the programmed procedure of the machine tool. Machine round holes on the mounting plate (100) to make the embedded holes (101).

5. The manufacturing process of a high-altitude balloon radar reflector according to claim 2, characterized in that, Specifically, step 3) is as follows: First, protect the entire mounting plate (100) with transparent tape, then clean the tape at all the embedded holes (101). Inject the prepared adhesive into the embedded holes (101), put in the embedded parts (200), press the embedded parts (200) to the bottom, scrape the overflowing adhesive flat. When the adhesive has not completely dried, clean the surface and remove the excess glue, and make the adhesive cure at room temperature.

6. The manufacturing process of a high-altitude balloon radar reflector according to claim 2, characterized in that, Before step 5) of installing the array of reflection units after step 4) of the second machining, a protection treatment is also carried out. Specifically, first clean the residues machined in the threaded holes (201). After cleaning, protect the pin holes (102) and the threaded holes (201) with cylindrical pins and screws, and then brush the flanged edges around the mounting plate (100) with chopped carbon fiber and epoxy resin glue.

7. The manufacturing process of a high-altitude balloon radar reflector according to claim 6, characterized in that, After protecting the threaded holes (201) and the pin holes (102) with screws and cylindrical pins, flame spraying aluminum is carried out on the parts that need to be sprayed with aluminum, and the sprayed aluminum layer is protected with a sealing agent after spraying.

8. The manufacturing process of a high-altitude balloon radar reflector according to claim 7, characterized in that, The installation plate (100) after spraying aluminum needs to be inspected for machining dimensions and internal quality. It can be put into the transfer product warehouse for subsequent assembly and use only after ensuring that there are no problems.

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