An embedded metal tube structure and its fabrication method

Abstract

This invention discloses an embedded metal tube structure and its fabrication method, comprising a substrate, a metal tube, solder, an isolation layer, and a cover plate. The substrate has an embedding groove, with stepped surfaces formed on both opposite side walls of the groove. The metal tube passes through the embedding groove, and the solder fills the groove, covering all parts of the outer side of the metal tube and forming a brazed layer. The upper end face of the brazed layer has solder grooves near both side walls of the embedding groove. The isolation layer is located on the upper end face of the brazed layer, spanning between the two stepped surfaces and contacting the upper end face of the brazed layer. The cover plate is located on the isolation layer, and weld gaps are formed between the opposite sides of the cover plate and the opposite sides of the embedding groove. This invention solves the problems of thermal barriers between the existing brazed layer and the cover plate, and the tendency for hot cracking to occur in the weld when the cover plate is welded to the substrate.

Description

Technical Field

[0001] This invention relates to the field of brazing technology, specifically to an embedded metal tube structure and its preparation method. Background Technology

[0002] Arranging metal tubes on a metal substrate is one of the common structural forms of heat exchange systems in industrial equipment. In order to improve heat exchange efficiency, it is necessary to open grooves on the surface of the metal substrate and embed metal tubes. This structure is called embedded metal tube structure. Patent document with patent number CN104588808A discloses the use of vacuum brazing to weld water-cooled tubes on a metal material plate workpiece with embedded grooves. The preparation method forms a metallurgical bond at the connection interface, so that the joint has better heat exchange performance.

[0003] As the application fields of industrial equipment continue to expand, embedded metal pipe joints in metal substrates will be affected by factors such as structural loads and environmental corrosion, which puts forward more stringent requirements on the overall structure's service performance in extreme environments.

[0004] To protect brazed joints, a common method is to weld a metal cover plate over the joint for sealing. However, the metal cover plate needs to be connected to the metal substrate using fusion welding or solid-state welding. These welding methods involve high-temperature and concentrated heat sources. The brazed joint of the embedded metal tube on the surface of the metal substrate is highly susceptible to solder loss due to the high temperature during cover plate welding, which will damage the heat transfer performance of the embedded metal tube structure. In addition, after the molten solder penetrates the weld, the low-melting-point solder components will form low-melting-point eutectics with the weld metal. During the solidification process of the weld, these low-melting-point eutectics will undergo microsegregation. Under the combined effect of grain boundary weakening and shrinkage stress, hot cracks in the cover plate weld are easily induced, which will seriously affect the reliability and corrosion resistance of the embedded metal tube structure in extreme environments. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide an embedded metal tube structure and preparation method, solving the problems of thermal barrier between the brazing layer and the cover plate and the easy generation of hot cracks in the weld when the cover plate is welded to the substrate in the prior art.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an embedded metal tube structure, comprising: The substrate has an inlay groove, and the opposite side walls of the inlay groove are formed with stepped surfaces. A metal tube, wherein the metal tube is inserted into the inlay groove; Solder, the solder fills the inlay groove, and the solder covers all parts of the outside of the metal tube and forms a brazing layer, and the upper end surface of the brazing layer has solder grooves near the two side walls of the inlay groove; An isolation layer, wherein the isolation layer spans between the two stepped surfaces and contacts the upper end surface of the brazing layer; and, A cover plate is disposed on the isolation layer, and welded gaps are formed between the opposite sides of the cover plate and the opposite side walls of the inlay groove.

[0007] In one embodiment, the insulating layer is a thermosetting resin layer.

[0008] In one embodiment, the isolation layer is a colloidal layer.

[0009] In one embodiment, the colloidal layer is one or more of the following: adhesive graphene film, adhesive fiberglass cloth, adhesive aluminum foil, or adhesive copper foil.

[0010] In one embodiment, the two stepped surfaces are respectively formed on the two side walls of the inlay groove near the top opening, and the inlay groove is a U-shaped inlay groove, a V-shaped inlay groove, or a rectangular inlay groove.

[0011] In one embodiment, the substrate and the metal tube are made of stainless steel, copper, or aluminum alloy.

[0012] In one embodiment, the solder is an In alloy, Sn alloy, Al alloy, or Ag alloy.

[0013] Secondly, the present invention also provides a welding method for an embedded metal tube, the preparation method being used to manufacture the above-mentioned embedded metal tube structure, the preparation method comprising the following steps: An inlay groove is made on the surface of the substrate, and stepped surfaces are provided on the opposite side walls of the inlay groove; Place the metal tube to be welded into the inlay groove; The inlay groove is filled with solder, which covers all parts of the outside of the metal tube and forms a brazing layer. The upper end face of the brazing layer has solder grooves near the two side walls of the inlay groove. The isolation layer is placed between the two stepped surfaces and in contact with the upper surface of the brazing layer; The cover plate is placed on the isolation layer, and welded gaps are formed between the opposite sides of the cover plate and the opposite side walls of the inlay groove. The cover plate is welded to the base material using either fusion welding or solid phase welding.

[0014] In some embodiments, the following steps are also included: After the solder fills the inlay groove, the two side walls of the inlay groove above the solder layer are cleaned with a scraper.

[0015] In some embodiments, the following steps are also included: After the isolation layer is placed on the upper surface of the brazing layer, the two side walls of the inlay groove located above the isolation layer are cleaned with a scraper.

[0016] Compared with the prior art, the present invention provides an embedded metal tube structure and manufacturing method, wherein an embedding groove is formed in the substrate, and the opposite side walls of the embedding groove are both formed with stepped surfaces. The metal tube passes through the embedding groove, and solder fills the embedding groove, covering all parts of the outside of the metal tube and forming a brazing layer. The upper end face of the brazing layer has solder grooves near the opposite side walls of the embedding groove. An isolation layer is disposed between the two stepped surfaces and in contact with the upper end face of the brazing layer. A cover plate is disposed on the isolation layer, and welding gaps are formed between the opposite sides of the cover plate and the opposite side walls of the embedding groove. The cover plate sealing welding method can achieve... To enhance the overall structure's reliability and corrosion resistance in extreme environments, an isolation layer is placed on the surface of the brazed layer within the embedding groove to seal the brazed joint. This isolation layer bridges the thermal barrier between the brazed layer and the cover plate, and prevents the solder from melting due to high temperatures during cover plate welding, which could then seep into the weld gap and cause thermal cracking. The stepped surface separates the brazed layer from the heat source of the cover plate welding, and the solder groove increases the thickness of the isolation layer at the edge of the brazed layer, further preventing low-melting-point solder from entering the welding gap of the cover plate. After the cover plate is welded, the brazed layer is not damaged, ensuring that the overall structure has good heat exchange performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an embedded metal tube structure provided by the present invention; Figure 2 This is a schematic diagram of the structure of the substrate provided by the present invention; Figure 3 This is a partial structural schematic diagram of an embedded metal tube structure provided by the present invention; Figure 4 This is a schematic diagram of the structure of an embedded metal tube after welding, provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] To address the technical problems in existing technologies, such as the existence of a thermal barrier between the brazed layer and the cover plate, and the susceptibility of hot cracking in the weld seam during welding of the cover plate to the substrate, this solution provides an embedded metal tube structure and its fabrication method. By setting an isolation layer on the upper surface of the formed brazed layer, the cover plate is isolated from the brazed layer. Furthermore, the stepped surface and the solder groove of the brazed layer further isolate the weld seam of the cover plate from the brazed layer, preventing the brazed layer from melting due to high temperatures during welding of the cover plate to the substrate, thus avoiding the situation where molten solder seeps into the weld seam and causes hot cracking.

[0020] Firstly, please refer to Figures 1-4 , Figures 1-4 An embedded metal tube structure according to one embodiment of the present invention includes a substrate 1, a metal tube 2, a solder 3, an isolation layer 4, and a cover plate 5. The substrate 1 has an embedding groove 1a, and the opposite side walls of the embedding groove are formed with stepped surfaces. The metal tube 2 passes through the embedding groove 1a, the solder 3 fills the embedding groove 1a, and the solder 3 covers all parts of the outer side of the metal tube 2 to form a brazing layer. The upper end surface of the brazing layer has solder grooves near the opposite side walls of the embedding groove. The isolation layer 4 spans between the two stepped surfaces and contacts the upper end surface of the brazing layer. The cover plate 5 is disposed on the isolation layer 4, and welding gaps are formed between the opposite sides of the cover plate 5 and the opposite side walls of the embedding groove 1a.

[0021] In actual use, the metal tube 2 is inserted into the inlay groove 1a on the base 1, and the solder 3 is filled into the inlay groove 1a, covering all parts of the outside of the metal tube 2. The solder 3 forms a brazing layer on the outside of the metal tube 2, and the upper end surface of the brazing layer is a flat support surface. Solder grooves 3a are machined on both sides of the upper end surface of the brazing layer near the two side walls of the inlay groove. The isolation layer 4 spans between the two stepped surfaces and contacts the upper end surface of the brazing layer. It is necessary to ensure that the isolation layer 4 seals the upper end surface of the brazing layer. The cover plate 5 is placed in the inlay groove 1a, and welding gaps are formed between the opposite sides of the cover plate 5 and the opposite side walls of the inlay groove 1a. Welding equipment (not shown in the figure) is used to weld and fix the cover plate 5 to the base 1.

[0022] It should be noted that, in one embodiment, the isolation layer 4 is a thermosetting resin layer. Thermosetting resin layers generally refer to cured layers formed by using thermosetting resin as a matrix, and are widely used in composite materials, coatings, electronic packaging, and structural components. During the curing process, thermosetting resins undergo chemical cross-linking to form a three-dimensional network cross-linked structure, which has high heat resistance (glass transition temperature is usually higher than 180°C), excellent dimensional stability, and good corrosion resistance, wear resistance, and mechanical strength.

[0023] In another embodiment, the isolation layer 4 is an adhesive layer. It should be noted that the adhesive layer is one or more of the following: adhesive graphene film, adhesive fiberglass cloth, adhesive aluminum foil, or adhesive copper foil.

[0024] It should be noted that, based on the above scheme, the two stepped surfaces are respectively formed on the two side walls of the inlay groove near the top opening. The inlay groove 1a is a U-shaped inlay groove, a V-shaped inlay groove, or a rectangular inlay groove. In this specific embodiment, the inlay groove 1a is a U-shaped inlay groove.

[0025] It should be noted that when the cover plate 5 is placed in the inlay groove 1a, the top surface of the cover plate 5 and the top surface of the base 1 are in the same plane.

[0026] It should be noted that the substrate 1 and the metal tube 2 are made of copper. Of course, in other embodiments, the substrate 1 and the metal tube 2 may also be made of stainless steel or aluminum alloy.

[0027] It should be noted that solder is a filler metal material with a melting point lower than that of the metal being welded, used to connect two or more metal surfaces during the welding process. It achieves electrical and mechanical connection by wetting the surfaces of the metals being welded and forming an alloy layer at the contact interface.

[0028] In one embodiment, the solder 3 is an In alloy. Of course, in other embodiments, the solder 3 may also be a Sn alloy, an Al alloy, or an Ag alloy.

[0029] In a first aspect, the present invention also provides a method for manufacturing an embedded metal tube, the method being used to manufacture the aforementioned embedded metal tube structure, the method comprising the following steps: (a) An inlay groove 1a is formed on the surface of the substrate 1; According to the design requirements, an inlay groove 1a for embedding the metal tube 2 is machined at a designated location on the substrate 1, and stepped surfaces are provided on both opposite side walls of the inlay groove. The cross-sectional profile of the inlay groove 1a and the outer cross-sectional profile of the metal tube 2 can be U-shaped, rectangular, or V-shaped. The size of the inlay groove 1a is slightly larger than the outer diameter of the metal tube 2 to ensure that the metal tube 2 can be placed inside the inlay groove 1a. The substrate can be made of copper, and the metal tube 2 can be a copper tube. Before the metal tube 2 is placed into the inlay groove 1a, the wall surface of the inlay groove 1a and the outer wall surface of the metal tube 2 are sanded with 180-grit sandpaper. Then, the wall surface of the inlay groove 1a and the outer wall surface of the metal tube 2 are wiped clean with lint-free paper soaked in anhydrous ethanol and air-dried to remove surface impurities as much as possible and avoid impurities affecting the interfacial bonding strength of the metal tube 2.

[0030] (ii) Place the metal pipe to be welded into the mounting groove; The pre-treated metal tube 2 to be brazed is placed in the inlay groove 1a to ensure that the position of the metal tube 2 in the inlay groove 1a is accurate.

[0031] (iii) Fill the inlay groove 1a with solder 3 so that the solder 3 covers all parts of the outside of the metal tube and forms a brazing layer. The amount of solder 3 should be reasonably determined according to the size of the inlay groove 1a and the specifications of the metal tube 2. It is necessary to ensure that the upper end surface of the brazing layer is a flat support surface, and solder grooves 3a are set on the upper end surface of the brazing layer near the two side walls of the inlay groove. (iv) The isolation layer 4 is located between the two stepped surfaces and in contact with the upper surface of the brazing layer, and the isolation layer 4 seals the entire brazing layer.

[0032] (v) Place the cover plate 5 on the isolation layer, and make a welding gap between the opposite sides of the cover plate 5 and the opposite sides of the inlay groove 1a; weld the cover plate 5 to the substrate 1 by means of fusion welding or solid phase welding.

[0033] It should be noted that, in one embodiment, the following steps are also included: After the solder 3 is filled into the inlay groove 1a, the two side walls of the inlay groove 1a above the brazing layer are cleaned with a scraper to remove the residual solder on the wall of the inlay groove 1a. After the isolation layer 4 is placed on the upper surface of the solder layer, the two side walls of the inlay groove located above the isolation layer are cleaned with a scraper to remove residual solder and adhesive material from the wall of the inlay groove 1a.

[0034] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for manufacturing an embedded metal tube, the method being used to fabricate an embedded metal tube structure, the embedded metal tube structure comprising: The substrate has an inlay groove, and the opposite side walls of the inlay groove are formed with stepped surfaces. A metal tube, wherein the metal tube is inserted into the inlay groove; Solder, the solder fills the inlay groove, and the solder covers all parts of the outside of the metal tube and forms a brazing layer, and the upper end surface of the brazing layer has solder grooves near the two side walls of the inlay groove; An isolation layer, wherein the isolation layer spans between the two stepped surfaces and contacts the upper end surface of the brazing layer; and, A cover plate is disposed on the isolation layer, and welded gaps are formed between the opposite sides of the cover plate and the opposite side walls of the inlay groove. The two stepped surfaces are respectively formed on both sides of the inlay groove near the top opening; The preparation method is characterized by comprising the following steps: An inlay groove is made on the surface of the substrate, and stepped surfaces are provided on the opposite side walls of the inlay groove; Place the metal tube to be welded into the inlay groove; Solder is filled into the mounting groove, and the solder covers all parts of the outside of the metal tube, forming a brazing layer. Furthermore, the upper end face of the brazing layer has solder grooves on both sides of the inlay groove. The isolation layer is placed between the two stepped surfaces and in contact with the upper surface of the brazing layer; The cover plate is placed on the isolation layer, and welded gaps are formed between the opposite sides of the cover plate and the opposite side walls of the inlay groove. The cover plate is welded to the base material using either fusion welding or solid phase welding.

2. The method for preparing an embedded metal tube according to claim 1, characterized in that, The insulating layer is a thermosetting resin layer.

3. The method for preparing an embedded metal tube according to claim 1, characterized in that, The isolation layer is a colloidal layer.

4. The method for preparing an embedded metal tube according to claim 3, characterized in that, The colloidal layer is one or more of the following: adhesive graphene film, adhesive fiberglass cloth, adhesive aluminum foil, or adhesive copper foil.

5. The method for preparing an embedded metal tube according to claim 1, characterized in that, The inlay groove is a U-shaped inlay groove, a V-shaped inlay groove, or a rectangular inlay groove.

6. The method for preparing an embedded metal tube according to claim 1, characterized in that, The substrate and the metal tube are made of stainless steel, copper or aluminum alloy.

7. The method for preparing an embedded metal tube according to claim 1, characterized in that, The solder is an In alloy, Sn alloy, Al alloy, or Ag alloy.

8. The method for preparing an embedded metal tube according to claim 1, characterized in that, It also includes the following steps: After the solder fills the inlay groove, the two side walls of the inlay groove above the solder layer are cleaned with a scraper.

9. The method for preparing an embedded metal tube according to claim 8, characterized in that, It also includes the following steps: After the isolation layer is placed on the upper surface of the brazing layer, the two side walls of the inlay groove located above the isolation layer are cleaned with a scraper.

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