High-strength composite shielding net for towed linear array and preparation method of high-strength composite shielding net

Abstract

The invention discloses a high-strength composite shielding net for a towed linear array and a preparation method of the high-strength composite shielding net. The composite shielding net comprises a metal shielding net, a grounding outgoing line and a polyurethane adhesive layer, the grid density of the metal shielding net is 100-200 meshes, and the thickness of the metal shielding net is not less than 0.04 mm; the thickness of the polyurethane adhesive layer ranges from 0.3 mm to 2 mm; one end of the grounding lead-out wire is connected with the metal shielding net, the polyurethane adhesive layer is solidified in grids of the metal shielding net and on the surface of a silk screen, the end, connected with the metal shielding net, of the grounding lead-out wire is embedded in the polyurethane adhesive layer, and the other end of the grounding lead-out wire extends out of the polyurethane adhesive layer. According to the invention, the comprehensive requirements of the towed linear array on shielding effectiveness, light weight, oil resistance, fatigue resistance under repeated bending and the like can be met at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of towed linear arrays, and in particular relates to a high-strength composite shielding net for towed linear arrays and a preparation method thereof. Background Art

[0002] A towed linear array is a thin, linear hydroacoustic detection device that has multiple hydrophones arranged in series and moves at a certain speed underwater. Hydroacoustic signals are transmitted in the ocean in the form of pressure waves. The piezoelectric elements of the hydrophones in the towed linear array convert the received pressure waves into weak voltage signals, which are then transmitted to the front-end circuit for signal amplification and other processing. Since the voltage signal output by the hydrophone is very weak and easily interfered by the electromagnetic field in space, it is necessary to equip the hydrophone, transmission line, and front-end circuit with electromagnetic shielding measures before amplification and digitization to isolate and weaken electromagnetic radiation in space and ensure good signal quality.

[0003] Common electromagnetic shielding measures include metal shells, non-metal shielding nets, metal shielding nets and other shielding materials. For example, Chen Qingrui, Hu Jianhui, Wang Minhui, Ouyang Xun, Liu Jia and Li Ke’s “Preparation Method and Process of Underwater Acoustic Transducer Shielding Layer” uses conductive glue to apply on the surface of polyurethane glue and connects to the metal shell through bare copper wire; however, the metal shell is heavy, which affects the transmission of high-frequency underwater acoustic signals. Due to the bending diameter requirements of the towed line array, it is only suitable for the shielding of a single hydrophone, not for the occasions where multiple hydrophones are grouped at intervals. Moreover, non-metallic materials such as conductive glue and conductive rubber are prone to aging in the filling oil, and effective connection with the circuit ground wire is also a problem. The non-metallic shielding net is light in weight and has good bending resistance, but it cannot be connected to the circuit ground wire through welding. Moreover, after long-term use, the metal conductive layer on the surface of the non-metallic wire may fall off in the towed line array filling oil, resulting in a decrease in the shielding effect. The fallen metal material will move with the filling oil, causing a circuit short circuit. The metal shielding mesh is light in weight, has good shielding effect, and can be welded, but the wire mesh is easily broken due to material fatigue during the repeated retraction and bending of the towed array, resulting in shielding failure; for example, the "High-Strength Composite High-Frequency Screen Manufacturing Technology" of Baotou Shibao Iron Ore Group Co., Ltd. adopts a three-layer tightly fitted mesh structure. Although its strength is improved, the weight is significantly increased, and it requires a larger space in the towed array. Summary of the invention

[0004] The purpose of the present invention is to provide a high-strength composite shielding net for a towed linear array and a preparation method thereof, so as to solve the problem that the existing shielding measures proposed in the background technology cannot simultaneously meet the comprehensive requirements of the towed linear array for shielding effectiveness, light weight, oil resistance, fatigue resistance under repeated bending, etc.

[0005] To achieve the above object, the present invention provides the following technical solutions: A high-strength composite shielding net for a towed line array comprises a metal shielding net, a grounding lead wire and a polyurethane adhesive layer; the mesh density of the metal shielding net is 100-200 meshes, and the thickness is not less than 0.04mm; the thickness of the polyurethane adhesive layer is between 0.3mm and 2mm; one end of the grounding lead wire is connected to the metal shielding net, the polyurethane adhesive layer is solidified in the mesh of the metal shielding net and on the surface of the wire mesh, the connecting end of the grounding lead wire and the metal shielding net is embedded in the polyurethane adhesive layer, and the other end of the grounding lead wire extends to the outside of the polyurethane adhesive layer.

[0006] Preferably, the metal shielding mesh is a grid structure woven with metal wires, and the diameter of the metal wires is between 0.04 mm and 0.1 mm.

[0007] Preferably, one end of the ground lead is fixed to the metal shielding mesh by welding.

[0008] Preferably, the polyurethane adhesive layer is made of a material that is resistant to swelling by filling oil.

[0009] A method for preparing a high-strength composite shielding net for a towed linear array, the method comprising: The connection step is to connect one end of the ground lead wire to a preset connection point of the metal shielding net; In the wetting step, the metal shielding mesh and the root of the ground lead are completely immersed in the polyurethane glue; In the curing step, the metal shielding mesh and the grounding lead wire soaked with the polyurethane adhesive are taken out and heated for curing.

[0010] Preferably, the impregnation step further comprises evacuating the polyurethane glue to remove bubbles in the metal shielding mesh.

[0011] Preferably, the impregnation step and the curing step are cyclically repeated multiple times until the polyurethane adhesive layer reaches a preset thickness.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The present invention combines a polyurethane adhesive layer with an ordinary metal shielding mesh to improve fatigue strength, and can simultaneously meet the comprehensive requirements of the towed linear array for shielding effectiveness, light weight, oil resistance, and fatigue resistance under repeated bending. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a front view of the high-strength composite shielding net for the towed linear array of this embodiment.

[0014] Figure 2 for Figure 1 Side view of. DETAILED DESCRIPTION

[0015] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0016] Reference Figure 1-2 As shown, a high-strength composite shielding net for a towed line array includes a metal shielding net 1, a polyurethane adhesive layer 2 and a grounding lead 3. The metal shielding net 1 is woven with wires with a diameter of 0.04 mm to 0.1 mm to form a grid structure. The wires are made of common electromagnetic shielding metal materials such as copper and monel. The metal wires are relatively thin, which achieves lightweight while having a certain strength. The mesh density of the woven metal shielding net 1 is between 100 mesh and 200 mesh, and the thickness of the shielding net is not less than 0.04 mm. The mesh of the metal shielding net 1 is relatively dense and can meet the electromagnetic shielding structure. One end of the grounding lead 3 is connected to the metal shielding net 1 to form an effective connection, and the other end of the grounding lead 3 is a free end.

[0017] In the present invention, the diameter of the braided metal wire is related to the mesh number of the metal shielding net 1. The higher the mesh number requirement, the denser the mesh, and the smaller the diameter of the metal wire used.

[0018] The polyurethane adhesive layer 2 is made of soft polyurethane adhesive with a thickness between 0.3mm and 2mm, which ensures the lightness of the composite shielding net while having high strength to achieve the bending of the composite shielding net; the specific thickness of the polyurethane adhesive layer 2 depends on the stress environment of the shielding net. The greater the stress, the higher the strength requirement, and the greater the thickness requirement of the polyurethane adhesive layer 2.

[0019] In the present invention, the filling oil of the dragging linear array is generally solvent naphtha, silicone oil or castor oil. The polyurethane adhesive is selected from a polyurethane material that can resist swelling of the filling oil. The polyurethane material is composed of polyether, isocyanate and curing agent, and the polyether, isocyanate and curing agent are all selected from a system with strong polarity. For example, the polyether is selected from polytetrahydrofuran polyol or propylene oxide polyether and its copolyether, the isocyanate is selected from TDI, MDI or PAPI, and the curing agent is selected from MOCA or 1,4-butanediol.

[0020] The polyurethane adhesive layer 2 is coated on the outside of the metal shielding layer. Specifically, the polyurethane adhesive layer 2 is solidified in the mesh and the surface of the wire mesh of the metal shielding net 1. The single-layer metal shielding net 1 is used as the base material, which has the advantages of light weight, good shielding effect, and weldability. The polyurethane adhesive layer 2 assists in enhancing the strength of the metal shielding net by coating. Compared with the upper and lower layer connection form, it can effectively improve the fatigue strength of the shielding metal net when it is repeatedly bent by the towed linear array. At the same time, the thickness of the adhesive layer is moderate, which will not significantly increase the weight of the shielding net and the space occupied.

[0021] The high-strength composite shielding net for towed linear array comprises the following steps: (1) Connection step: one end of the ground lead wire 3 is connected to the metal shielding mesh 1 at the required position by welding or other means to form an effective and reliable connection; (2) In the wetting step, the metal shielding mesh 1 and the root of the ground lead wire 3 are completely immersed in the prepared liquid polyurethane glue; (3) Curing step: take out the metal shielding mesh 1 and the grounding lead wire 3 soaked with polyurethane glue, and heat and cure them.

[0022] In the present invention, before the connection step is performed, the metal shielding net 1 can be cut according to the required size, or the cut metal shielding net can be processed into any required shape. The size and shape of the metal shielding net 1 depend on the towed linear array, and only need to completely enclose the hydrophone, transmission line, and front circuit in the towed linear array.

[0023] In the present invention, during the wetting step, the liquid polyurethane adhesive may be vacuumed to remove air bubbles in the mesh of the metal shielding net 1 when necessary.

[0024] In the present invention, the impregnation step and the curing step can be repeated for multiple times to make the polyurethane adhesive layer 2 reach a sufficient thickness.

[0025] In the present invention, a mold can also be used for pouring, the height of the mold cavity determines the thickness of the polyurethane adhesive layer 2, and then the mold is heated and cured.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength composite shielding net for a towed linear array, characterized in that: It includes a metal shielding mesh, a grounding lead wire and a polyurethane adhesive layer; the mesh density of the metal shielding mesh is 100-200 meshes, and the thickness is not less than 0.04mm; the thickness of the polyurethane adhesive layer is between 0.3mm and 2mm; one end of the grounding lead wire is connected to the metal shielding mesh, the polyurethane adhesive layer is solidified in the mesh of the metal shielding mesh and on the surface of the wire mesh, the connecting end of the grounding lead wire and the metal shielding mesh is embedded in the polyurethane adhesive layer, and the other end of the grounding lead wire extends to the outside of the polyurethane adhesive layer.

2. A high-strength composite shielding net for a towed linear array as claimed in claim 1, characterized in that: The metal shielding net is a grid structure woven with metal wires, and the diameter of the metal wires is between 0.04mm and 0.1mm.

3. A high-strength composite shielding net for a towed linear array as claimed in claim 1, characterized in that: One end of the ground lead is fixed to the metal shielding mesh by welding.

4. A high-strength composite shielding net for a towed linear array as claimed in claim 1, characterized in that: The polyurethane adhesive layer is made of a material that is resistant to swelling by filling oil.

5. A method for preparing the high-strength composite shielding net for towed linear array according to any one of claims 1 to 4, characterized in that: The method comprises: The connection step is to connect one end of the ground lead wire to a preset connection point of the metal shielding net; In the wetting step, the metal shielding mesh and the root of the ground lead are completely immersed in the polyurethane glue; In the curing step, the metal shielding mesh and the grounding lead wire soaked with the polyurethane adhesive are taken out and heated for curing.

6. A method for preparing a high-strength composite shielding net for a towed linear array as claimed in claim 5, characterized in that: The infiltration step also includes vacuuming the polyurethane glue to remove bubbles in the metal shielding mesh.

7. A method for preparing a high-strength composite shielding net for a towed linear array as claimed in claim 6, characterized in that: The infiltration step and the curing step are repeated multiple times until the polyurethane adhesive layer reaches a preset thickness.

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