Steel-aluminum pipe joint
By combining a sealed thread structure with a brazing process, the problems of unstable quality and low efficiency in the production of existing steel-aluminum pipe fittings have been solved, enabling the production of large-size pipe fittings with high precision and high efficiency, and improving tensile strength and structural stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SUZHOU SANCHUAN HEAT EXCHANGER CO LTD
- Filing Date
- 2025-06-17
- Publication Date
- 2026-06-09
AI Technical Summary
The existing production process for steel-aluminum pipe joints suffers from problems such as unstable quality, low tensile strength, and difficulty in large-scale production of large-sized workpieces. In particular, the traditional welding process is subject to strict limitations on the power grid, resulting in low production efficiency.
The system employs a sealed threaded structure combined with brazing technology. Through the precise meshing of external and internal threads, and combined with methods such as flame brazing, salt bath brazing, or vacuum/non-vacuum furnace brazing, it achieves simultaneous brazing of multiple pipe fittings. The external and internal threads are designed to be tapered with a 55° thread profile angle, and are reinforced with a large-end structure to enhance structural strength.
It significantly improves production efficiency and assembly accuracy of pipe fittings, reduces power requirements, supports efficient production of large-size workpieces, enhances the axial and radial load-bearing capacity of pipe fittings, and reduces the risk of structural failure.
Smart Images
Figure CN224339660U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of fluid transmission equipment technology, specifically to a steel-aluminum pipe joint. Background Technology
[0002] In process systems where stainless steel piping is used in aluminum fluid process equipment, steel-aluminum joints are indispensable, mainly used for transitional connections between stainless steel and aluminum pipes.
[0003] The key processes in the existing steel-aluminum pipe joint production process are explosive welding, friction welding, resistance welding and flash welding to connect aluminum pipe ends and stainless steel pipe ends.
[0004] However, these connection methods still have the following shortcomings in practical use:
[0005] Explosive welding utilizes the high temperature and pressure generated by an explosive explosion to cover a flyer plate onto a substrate, completing the composite of two different materials. Explosive welding is completed instantaneously, with high explosion speed and energy, resulting in numerous uncertainties and highly unstable product quality. The sparseness of the welding flux, the control of the gap between the flyer plate and the substrate, and the surface treatment of the flyer plate and the substrate all directly affect the steel-aluminum composite ratio, leading to a decrease in the tensile strength of the steel-aluminum joint during use.
[0006] Friction welding has limitations on the thickness of the workpiece; if it is too thin, production will not be possible.
[0007] Resistance welding involves placing two workpieces in a fixture (which also serves as an electrode) and clamping them together so that their end faces are in contact and pressed together. A strong current is then applied, and the resistance heat of the contact surfaces is used to heat both sides of the contact surfaces to a plastic state. Then the power is cut off and upsetting pressure is applied (or no upsetting pressure is applied, only the pressure used during welding is maintained). After cooling down, a strong butt joint is formed.
[0008] Flash butt welding involves clamping the workpieces in a fixture (which also serves as the electrode), applying current, and then slowly bringing the two workpiece end faces together. Initially, only a few high points on the end faces make contact, and due to the high current density, they melt to form a molten metal bridge. The bridge temperature further increases, causing the surrounding area to heat up until the center vaporizes, forming bubbles that burst and break. Some of the foamed liquid is ejected outwards as sparks, creating the flash. The two workpieces are continuously fed in and brought together, with the next high point making contact again, followed by another burst, and this cycle continues. During this process, the flashes are continuous. Once the flashes heat the entire end face to a certain temperature, the power is cut off, and the workpieces are fed in at an accelerated speed with pressure forging. At this point, the flashes stop, and all the molten metal is squeezed out of the mating surface. The workpiece material cools down through plastic deformation, forming a strong butt joint.
[0009] Meanwhile, the aforementioned friction welding, resistance welding, and flash welding processes are all constrained by the power supply of the power grid, making it difficult to mass-produce large-sized workpieces.
[0010] Therefore, how to overcome the shortcomings of the existing technology mentioned above has become the subject of this utility model. Utility Model Content
[0011] This utility model provides a steel-aluminum pipe joint, which aims to solve the technical problems mentioned in the background art.
[0012] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a steel-aluminum pipe joint, comprising a first pipe and a second pipe, wherein the first pipe is a steel pipe and the second pipe is an aluminum pipe; the first pipe and the second pipe are coaxially arranged, and the tail end of the first pipe is directly opposite the head end of the second pipe; a sealing thread structure for fixing the two is provided between the tail end of the first pipe and the head end of the second pipe; the sealing thread structure includes a matched external thread and an internal thread; the internal thread is provided at the tail end of the first pipe, and the external thread is provided at the head end of the second pipe, and the tail end of the first pipe and the head end of the second pipe are guided to be inserted and threadedly fixed through the cooperation of the external thread and the internal thread; the sealing thread structure further includes a brazed sealing layer, which is provided between the external thread and the internal thread to form a sealed connection between the two.
[0013] The relevant content in the above plan is explained as follows:
[0014] In the above scheme, the external thread and the internal thread can cooperate with each other, which means that one is set on the outside of the first or second pipe and the other is set on the inside, and they can be threaded together.
[0015] The brazed sealing layer of this invention is formed using a brazing process. This process overcomes the limitations of traditional processes due to the power grid constraints, and the sealing layer can be prepared through various methods such as flame brazing, salt bath brazing, or vacuum / non-vacuum furnace brazing. Compared to traditional welding processes that require high current, this solution significantly reduces the power requirements. While meeting the basic brazing conditions, it supports the simultaneous brazing of multiple pipe joints, effectively improving production efficiency per unit time.
[0016] This utility model innovatively adopts a connection structure with precise engagement of external and internal threads, organically integrating the two processes of insertion positioning and thread tightening into one. This design not only breaks through the inherent limitations of traditional processes on pipe wall thickness, but also innovatively combines the self-locking characteristics and rapid engagement advantages of the threaded pair, enabling the assembly process of the first and second pipes to simultaneously achieve sub-millimeter-level positioning accuracy and second-level engagement speed, resulting in an exponential leap in assembly efficiency. Furthermore, this structure also possesses excellent dimensional compatibility, adapting to the assembly needs of pipeline systems of different specifications.
[0017] In a further technical solution, the sealing thread structure also includes a reinforcing head with an annular structure; the reinforcing head corresponds to the external thread and the internal thread, and is located on the outer periphery of the first pipe or the second pipe.
[0018] Because the internal threads are machined into the inner wall of the first or second pipe, the wall thickness in this area is reduced, resulting in relatively weak structural strength. When high-temperature or high-pressure fluids flow through this structural part, stress concentration can easily lead to crack propagation. This application introduces a large-end reinforcement structure design to specifically compensate for the wall thickness loss in the internal thread area, making the stress distribution on the pipe wall more uniform, thereby significantly reducing the risk of structural failure.
[0019] In a further technical solution, both the external thread and the internal thread are tapered thread structures with a set taper.
[0020] The tapered thread structure is designed to ensure high precision when the first and second tubes are inserted.
[0021] In a further technical solution, the set taper of both the external thread and the internal thread is 1:16; the thread angle of both the external thread and the internal thread is 55°.
[0022] With the above design, after the first and second pipes are connected, the tapered thread structure can ensure the axial load bearing capacity of the pipe joint.
[0023] In some specific embodiments, the external thread is provided at the beginning of the second pipe, and the internal thread is provided on the inner side wall of the end of the first pipe; the reinforcing head is provided on the outer side wall of the end of the first pipe, and the inner diameter of the reinforcing head is equal to the outer diameter of the end of the first pipe.
[0024] The above describes one implementation of external and internal threads. In this implementation, the first end of the second pipe is inserted into the end of the first pipe, and a fixed connection is achieved through the cooperation of external and internal threads. After the fixed connection is completed, reinforcing the large end can ensure the radial load-bearing capacity of the pipe joint.
[0025] A further technical solution involves taking the length direction of the steel-aluminum pipe joint as a reference, wherein the projected length of the reinforcing large head is greater than the projected length of the threaded mating surface.
[0026] With the above design, the reinforced large end can fully compensate for the lack of wall thickness in the area where the threaded mating surface is located, so that the stress distribution of the pipe wall tends to be uniform.
[0027] The working principle involves the engagement of an external thread (located at the beginning of the second pipe) and an internal thread (located on the inner wall of the end of the first pipe) with a tapered thread to achieve axial positioning and mechanical locking. The unique 1:16 taper and 55° thread angle of the tapered thread generate radial clamping force during tightening, forming a preliminary sealing interface. Then, brazing is used to form a brazed sealing layer on the threaded mating surface. During use, the reinforced large end can effectively compensate for the wall thickness deficiency in the area where the threaded mating surface is located, making the stress distribution on the pipe wall more uniform.
[0028] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.
[0029] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.
[0030] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.
[0031] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the case.
[0032] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.
[0033] The working principle and advantages of this utility model are as follows:
[0034] The brazed sealing layer of this invention is formed using a brazing process. This process overcomes the limitations of traditional processes due to the power grid constraints, and the sealing layer can be prepared through various methods such as flame brazing, salt bath brazing, or vacuum / non-vacuum furnace brazing. Compared to traditional welding processes that require high current, this solution significantly reduces the power requirements. While meeting the basic brazing conditions, it supports the simultaneous brazing of multiple pipe joints, effectively improving production efficiency per unit time.
[0035] This utility model adopts an interlocking connection structure of external and internal threads to integrate the processes of insertion positioning and thread fastening. This design not only breaks through the limitations of traditional processes on pipe wall thickness, but also, through the self-locking characteristics of the threads and the advantage of rapid engagement, enables the assembly operation of the first and second pipes to achieve both high precision and high efficiency, significantly improving the assembly efficiency of the pipeline system. Attached Figure Description
[0036] Appendix Figure 1 This is a schematic diagram of the structure of the first tube and the second tube before brazing in an embodiment of this utility model.
[0037] Appendix Figure 2 This is a schematic diagram of the structure of the first tube and the second tube after brazing in an embodiment of this utility model;
[0038] Appendix Figure 3 This is a schematic diagram of the external thread structure in an embodiment of the present utility model;
[0039] Appendix Figure 4 This is a schematic diagram of the internal thread structure in an embodiment of the present utility model.
[0040] In the above attached diagram: 1. First tube; 2. Second tube; 3. External thread; 4. Internal thread; 5. Brazed sealing layer; 6. Reinforced big end; α. Thread tooth angle; A. Brazing filler metal. Detailed Implementation
[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0042] Example: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the examples of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.
[0043] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.
[0044] See appendix Figures 1-4As shown, a steel-aluminum pipe joint includes a first pipe 1 and a second pipe 2, wherein the first pipe 1 is a steel pipe and the second pipe 2 is an aluminum pipe; the first pipe 1 and the second pipe 2 are coaxially arranged, and the tail end of the first pipe 1 is directly opposite the head end of the second pipe 2; a sealing thread structure for fixing the two is provided between the tail end of the first pipe 1 and the head end of the second pipe 2; the sealing thread structure includes a matched external thread 3 and an internal thread 4; the internal thread 4 is provided at the tail end of the first pipe 1, and the external thread 3 is provided at the head end of the second pipe 2. Through the cooperation of the external thread 3 and the internal thread 4, the tail end of the first pipe 1 and the head end of the second pipe 2 are guided to be inserted and threadedly fixed; the sealing thread structure also includes a brazed sealing layer 5, which is provided between the external thread 3 and the internal thread 4 to form a sealed connection between the two.
[0045] In this embodiment, the external thread 3 and the internal thread 4 can cooperate with each other, meaning that one is located on the outside of the first pipe 1 or the second pipe 2, and the other is located on the inside, and they can be threaded together.
[0046] The brazed sealing layer 5 of this invention is formed using a brazing process. This process overcomes the limitations of traditional power grids and allows for the preparation of the sealing layer through various methods such as flame brazing, salt bath brazing, or vacuum / non-vacuum furnace brazing. Compared to traditional welding processes that require high current, this solution significantly reduces the power requirements. While meeting the basic brazing conditions, it supports the simultaneous brazing of multiple pipe joints, effectively improving production efficiency per unit time.
[0047] This utility model adopts an interlocking connection structure of external thread 3 and internal thread 4 to integrate the processes of insertion positioning and thread fastening. This design not only breaks through the limitations of traditional processes on pipe wall thickness, but also, through the self-locking characteristics of the threads and the advantage of rapid engagement, enables the assembly operation of the first pipe 1 and the second pipe 2 to achieve both high precision and high efficiency, significantly improving the assembly efficiency of the pipeline system.
[0048] It should be noted that, referring to Figure 1 Point A represents the brazing filler metal, showing the state of the first and second tubes before brazing.
[0049] Preferably, the sealing thread structure further includes a reinforcing head 6 in the form of an annular structure; the reinforcing head 6 corresponds to the external thread 3 and the internal thread 4, and is located on the outer periphery of the first pipe 1 or the second pipe 2.
[0050] Since the internal thread 4 needs to be machined into the inner wall of the first pipe 1 or the second pipe 2, the wall thickness in this area is reduced, resulting in relatively weak structural strength. When high-temperature or high-pressure fluid flows through this structural part, stress concentration can easily lead to crack propagation. This application introduces a large-end reinforcement structure design to specifically compensate for the lack of wall thickness in the area of the internal thread 4, making the stress distribution of the pipe wall more uniform, thereby significantly reducing the risk of structural failure.
[0051] Preferably, both the external thread 3 and the internal thread 4 are tapered thread structures with a set taper. With the above design, the tapered thread structure is designed to make the first tube 1 and the second tube 2 have high precision when inserted, and at the same time facilitate the formation of the brazing sealing layer 5.
[0052] Preferably, the set taper of the external thread 3 and the internal thread 4 is 1:16; the thread profile angle α of the external thread 3 and the internal thread 4 is 55°. With the above design, after the first pipe 1 and the second pipe 2 are connected, the tapered thread structure can ensure the bearing capacity of the pipe joint for axial load.
[0053] Preferably, the external thread 3 is disposed at the beginning end of the second pipe 2, and the internal thread 4 is disposed on the inner side wall of the end of the first pipe 1; the reinforcing head 6 is disposed on the outer side wall of the end of the first pipe 1, and the inner diameter of the reinforcing head 6 is equal to the outer diameter of the end of the first pipe 1. The above is one embodiment of the external thread 3 and the internal thread 4. In this embodiment, the beginning end of the second pipe 2 is inserted into the end of the first pipe 1, and a fixed connection is achieved through the cooperation of the external thread 3 and the internal thread 4. After the fixed connection is completed, the reinforcing head 6 can ensure the radial bearing capacity of the pipe joint.
[0054] The second tube 2 is an aluminum tube, and the first tube 1 is a steel tube, specifically a stainless steel tube (but this is not limited to this single embodiment; the first tube 1 can also be an aluminum tube). For example... Figure 1 As shown, the brazed sealing layer 5 is formed by penetration from the outside to the inside.
[0055] Preferably, taking the length direction of the steel-aluminum pipe joint as a reference, the projected length of the reinforcing head 6 is greater than the projected length of the threaded mating surface. With the above design, the reinforcing head 6 can fully compensate for the lack of wall thickness in the area where the threaded mating surface is located, so that the stress distribution of the pipe wall tends to be uniform.
[0056] The working principle involves the engagement of the external thread 3 (located at the beginning of the second pipe 2) and the internal thread 4 (located on the inner side wall of the end of the first pipe 1) with a tapered thread to achieve axial positioning and mechanical locking. The unique 1:16 taper and 55° thread angle of the tapered thread generate radial clamping force during tightening, forming a preliminary sealing interface. Then, a brazed sealing layer 5 is formed on the threaded mating surface by brazing. In use, the reinforced large end 6 can fully compensate for the lack of wall thickness in the area where the threaded mating surface is located, making the stress distribution of the pipe wall more uniform.
[0057] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.
Claims
1. A steel-aluminum pipe joint, characterized in that: It includes a first pipe (1) and a second pipe (2), the first pipe (1) being a steel pipe and the second pipe (2) being an aluminum pipe; The first tube (1) and the second tube (2) are coaxially arranged, and the tail end of the first tube (1) is directly opposite the head end of the second tube (2); A sealing thread structure for fixing the two is provided between the tail end of the first tube (1) and the head end of the second tube (2); The sealing thread structure includes a matched external thread (3) and an internal thread (4); The internal thread (4) is provided at the tail end of the first tube (1), and the external thread (3) is provided at the head end of the second tube (2). Through the cooperation of the external thread (3) and the internal thread (4), the tail end of the first tube (1) and the head end of the second tube (2) are guided to be inserted and threadedly fixed. The sealing thread structure also includes a brazed sealing layer (5), which is disposed between the external thread (3) and the internal thread (4) to form a sealed connection between them.
2. The steel-aluminum pipe joint according to claim 1, characterized in that: The sealing thread structure also includes a reinforcing large head (6) with a ring structure. The reinforced head (6) corresponds to the external thread (3) and the internal thread (4), and is located on the outer periphery of the first tube (1) or the second tube (2).
3. The steel-aluminum pipe joint according to claim 1 or 2, characterized in that: Both the external thread (3) and the internal thread (4) are tapered thread structures with a set taper.
4. The steel-aluminum pipe joint according to claim 3, characterized in that: The set taper of both the external thread (3) and the internal thread (4) is 1:16; The thread angle (α) of the external thread (3) and the internal thread (4) is 55°.
5. The steel-aluminum pipe joint according to claim 2, characterized in that: The external thread (3) is provided at the beginning of the second tube (2), and the internal thread (4) is provided on the inner side wall of the end of the first tube (1). The reinforcing head (6) is located on the outer side wall of the tail end of the first pipe (1), and the inner diameter of the reinforcing head (6) is equal to the outer diameter of the tail end of the first pipe (1).
6. The steel-aluminum pipe joint according to claim 2, characterized in that: Based on the length direction of the steel-aluminum pipe joint, the projected length of the reinforced large head (6) is greater than the projected length of the threaded mating surface.