Pipe end sealing device for internal pressure bulging of internal threaded pipe
By designing a pipe end sealing device that is pressure-expanded inside the internally threaded pipe, the problems of internal thread damage and loose sealing caused by mechanical expansion are solved, achieving efficient sealing, long life, and adaptability to automated production of multiple specifications, thereby improving the heat exchange efficiency and structural integrity of the air-conditioning heat exchanger.
Patent Information
- Application Number
- CN202511090644.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2025-09-12
AI Technical Summary
Existing mechanical expansion technology in air-conditioning heat exchangers has problems such as internal thread tooth damage, expansion accuracy affected by expansion bead wear, and poor sealing, which leads to reduced heat exchange efficiency and medium leakage, making it difficult to adapt to the needs of efficient heat exchange and automated production.
A pipe end sealing device for internal pressure expansion of internally threaded pipes is designed. The device adopts an extrusion sealing assembly consisting of an inner extrusion ring, an outer extrusion ring and a sealing ring. The outer extrusion ring is driven by a cylinder to achieve flexible sealing. The device is suitable for a variety of product specifications and can avoid medium leakage and damage to the internal threads.
It achieves efficient sealing and long-life pipe end sealing, adapts to automated production, protects internally threaded pipes from damage, is applicable to a variety of product specifications, and improves the heat exchange efficiency and structural integrity of the heat exchanger.
Smart Images
Figure CN120626744A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of pipe end sealing of air conditioner heat exchangers, in particular to a pipe end sealing device used for internal pressure expansion of an internally threaded pipe. Background Art
[0002] Refrigeration and air conditioning typically utilizes tube-and-fin heat exchangers. The heat exchange tubes feature an internally threaded, toothed structure to increase the heat exchange area between the heat exchanger and the refrigerant medium. Aluminum foil fins significantly increase the heat exchange area between the heat exchanger and the external environment. After the internally threaded heat exchange tubes and aluminum foil fins are assembled, an expansion process is used to increase the tube diameter, eliminating the gap between the tube and fin, creating a good interface contact and reducing the contact thermal resistance between the tube and fin, thereby achieving excellent heat exchange efficiency.
[0003] Mechanical expansion is widely used in the industry due to its technological maturity. This process uses a long rod to push a rigid expansion bead with a diameter larger than the inner diameter of the heat exchange tube into the tube along the axis, causing the heat exchange tube to undergo plastic deformation, increasing its diameter and making close contact with the fins. However, the air-conditioning industry has an increasingly urgent demand for high heat exchange efficiency and low production costs, and traditional mechanical expansion methods have gradually exposed their limitations. On the one hand, during the mechanical expansion process, the rigid contact between the expansion bead and the tip of the internal thread of the heat exchange tube can easily cause the internal thread profile to become shorter or tilted, affecting the flow of the refrigerant medium in the heat exchange tube, resulting in heat exchange efficiency failing to reach the ideal design value. On the other hand, the expansion accuracy of mechanical expansion is significantly affected by the wear of the expansion bead. After long-term use, the diameter of the expansion bead decreases, resulting in a decrease in the fit between the heat exchange tube and the fin after expansion, forming a high contact thermal resistance and weakening the heat exchange performance of the heat exchanger.
[0004] Faced with the limitations of mechanical expansion, the development of a new generation of expansion technology has become a breakthrough in the industry, with hydraulic expansion and pneumatic expansion attracting significant attention. Both utilize liquid and gas, respectively, as force transmission media, applying uniform internal pressure to the inner surface of the heat exchange tubes, thereby causing the tubes to bulge and form an expansion joint with the fins. Compared to mechanical expansion, fluid medium loading is flexible; there is no hard contact or friction between the medium and the internal threads of the heat exchange tubes, resulting in no damage to the internal thread profile. The uniform internal pressure of the fluid medium also effectively avoids the localized stress concentration problems associated with mechanical expansion caused by off-center loading and wear of the expansion beads, thereby improving the structural integrity and pressure resistance of the expanded heat exchange tubes.
[0005] Currently, hydraulic and pneumatic expansion have made some progress in research on expansion pressure control and expansion process simulation. However, their application in actual production still faces challenges, such as the stability of the high-pressure system, the effectiveness and stability of the tube end sealing structure, and the applicability of the process and equipment to heat exchangers of different specifications. When using fluid media such as liquids and gases to expand heat exchange tubes, due to the special nature of the fluid medium's easy flow, a sealing device is required at the tube end to prevent the medium from leaking. If the seal is not tight and the fluid medium leaks, it will be difficult for the fluid medium to generate sufficient pressure inside the heat exchange tube, and the heat exchange tube will not be able to complete the expansion connection with the fin.
[0006] In order to accelerate the application of new technologies such as hydraulic expansion and pneumatic expansion in the manufacturing field of air-conditioning heat exchangers, promote technological upgrading of the air-conditioning industry, and further improve the heat exchange efficiency of heat exchangers, there is an urgent need for internal threaded pipe end sealing devices for mass production. Summary of the Invention
[0007] The purpose of the present invention is to provide a pipe end sealing device for internal pressure expansion of internally threaded pipes, which meets the requirements of simple structure, high sealing efficiency, long service life, adaptability to automated production, and applicability to various product specifications.
[0008] To achieve the above-mentioned objectives, the present invention provides a pipe end sealing device for internal compression expansion of an internally threaded pipe, comprising a mounting block, on which an extrusion sealing assembly is provided, wherein the extrusion sealing assembly comprises an inner extrusion ring, an outer extrusion ring, and a sealing ring, wherein the outer extrusion ring is sleeved over the inner extrusion ring, the sealing ring is arranged between the outer extrusion ring and the inner extrusion ring, and the outer extrusion ring is connected to the mounting block via the piston rod of a cylinder.
[0009] Preferably, a groove is provided on the top of the mounting block, and the shape of the groove matches the structure of the bottom of the inner extrusion ring.
[0010] Preferably, the side wall of the groove is provided with an internal thread, the side surface of the bottom of the inner extrusion ring is provided with an external thread matching the internal thread, and the bottom of the inner extrusion ring is placed in the groove.
[0011] Preferably, a sealing gasket or an O-ring is provided between the inner extrusion ring and the mounting block.
[0012] Preferably, a pressurizing hole is provided on the mounting block, and the pressurizing hole is communicated with the inner hole on the inner extrusion ring.
[0013] Preferably, the longitudinal section of the outer extrusion ring is in the shape of an X, and the internal structure of the outer extrusion ring is consistent with the structure of the inner extrusion ring.
[0014] Preferably, the outer extrusion ring is provided with a through hole, the inner extrusion ring is provided with a countersunk hole, the through hole and the countersunk hole are concentric and have the same inner diameter, and the tube end of the internal threaded tube is placed in the through hole and the countersunk hole.
[0015] Preferably, the top end of the piston rod is fixedly connected to the outer extrusion ring, the cylinder is located at the bottom end of the piston rod, and the cylinder is fixedly arranged on the mounting block.
[0016] Therefore, the present invention adopts the above-mentioned pipe end sealing device for internal pressure expansion of internally threaded pipes, and the technical effects are:
[0017] It has a simple structure and is easy to operate, and can be used for automated sealing of pipe ends. The inner extrusion ring, outer extrusion ring, sealing ring and other sealing parts can be replaced with different specifications, making it easy to achieve pipe end sealing for products of various specifications. The pipe end does not contact the sealing ring during insertion and removal, which does not damage the sealing ring and increases the service life of the sealing device. It operates quickly and seals effectively. The flexible seal does not damage the pipe.
[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is an overall structural diagram of a first embodiment of a pipe end sealing device for internal pressure expansion of an internally threaded pipe according to the present invention;
[0020] Figure 2 This is a structural diagram of a sealing device using an extrusion ring with a cylindrical support core in Example 2 of a pipe end sealing device for internal compression expansion of an internally threaded pipe according to the present invention;
[0021] Figure 3 This is a structural diagram of a sealing device using an O-ring in a third embodiment of a pipe end sealing device for internal pressure expansion of an internally threaded pipe according to the present invention;
[0022] Figure 4 This is a structural diagram of a sealing device using an inner extrusion ring with a cylindrical support core and an O-ring according to a fourth embodiment of a pipe end sealing device for internal compression expansion of an internally threaded pipe of the present invention.
[0023] Reference numerals
[0024] 1. Outer extrusion ring; 2. Sealing ring; 3. Inner extrusion ring; 4. Sealing gasket; 5. Mounting block; 6. Cylinder; 7. Piston rod; 8. Inner extrusion ring with cylindrical support core; 9. O-ring; 10. Internal threaded pipe. DETAILED DESCRIPTION
[0025] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.
[0026] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words “include” or “comprise” and the like used in the present invention mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as “connect” or “connected” and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Up”, “down”, “left”, “right” and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.
[0027] Example 1
[0028] like Figure 1 As shown, the present invention provides a pipe end sealing device for internal compression expansion of internally threaded pipes, including a mounting block 5, on which is provided an extrusion sealing assembly, which includes an inner extrusion ring 3, an outer extrusion ring 1, and a sealing ring 2. The inner extrusion ring 3 is fixed to the mounting block 5 by threads. The top of the mounting block 5 is provided with a groove, the shape of which matches the structure of the bottom of the inner extrusion ring 3. The sidewalls of the groove are provided with internal threads, and the side surface of the bottom of the inner extrusion ring 3 is provided with external threads that match the internal threads. As a result, the bottom of the inner extrusion ring 3 is placed in the groove, so that the inner extrusion ring 3 is fixed to the mounting block 5.
[0029] At the same time, a sealing gasket 4 is provided on the end surface where the inner extrusion ring 3 cooperates with the mounting block 5, thereby ensuring the sealing performance of the device.
[0030] The outer extrusion ring 1 is sleeved on the inner extrusion ring 3. The longitudinal section of the outer extrusion ring 1 is in the shape of a cross. The internal structure of the outer extrusion ring 1 is consistent with the structure of the inner extrusion ring 3. The outer extrusion ring 1 is provided with a through hole, and the inner extrusion ring 3 is provided with a countersunk hole. The through hole and the countersunk hole are concentric and have the same inner diameter. The end of the internal threaded tube 10 is placed in the through hole and the countersunk hole.
[0031] The sealing ring 2 is a polyurethane sealing ring, which is arranged between the outer extrusion ring 1 and the inner extrusion ring 3 and is used to seal the gap between the outer surface of the internal threaded tube 10 and the outer extrusion ring 1 and the inner extrusion ring 3.
[0032] The mounting block 5 is provided with a pressurized hole, which is connected to the inner hole of the inner extrusion ring 3. The sealed tube, i.e., the internal threaded tube 10, is inserted into the channel formed by the outer extrusion ring 1, the sealing ring 2 and the inner extrusion ring 3, so that the pressurized hole is connected to the inner cavity of the tube.
[0033] The outer extrusion ring 1 is connected to the mounting block 5 via the piston rod 7 of the cylinder 6. The top of the piston rod 7 is fixedly connected to the outer extrusion ring 1. The cylinder 6 is located at the bottom of the piston rod 7 and is fixedly mounted on the mounting block 5. Under the action of the cylinder 6, the axial movement of the piston rod 7 drives the axial movement of the outer extrusion ring 1. The mounting block 5 can be fixed to a platform or mounted on a robot or other actuator to facilitate automation.
[0034] The specific working status is as follows:
[0035] In the free state, there is a gap between the inner diameters of the outer extrusion ring 1, sealing ring 2, and inner extrusion ring 3 and the surface of the internally threaded tube 10, facilitating the insertion of the tube end. During sealing, the tube end is first inserted into the inner bores of the outer extrusion ring 1, sealing ring 2, and inner extrusion ring 3. Then, the cylinder 6 drives the outer extrusion ring 1 downward via the piston rod 7 while the inner extrusion ring 3 remains stationary, exerting an axial compression on the sealing ring 2 between them. This causes the sealing ring 2 to be axially compressed and radially thickened, filling the gap between the outer extrusion ring 1, inner extrusion ring 3, and the sealed tube, thereby achieving a seal.
[0036] When releasing the seal, the cylinder 6 drives the outer extrusion ring 1 to move upward through the piston rod 7 while the inner extrusion ring 3 remains stationary. The two no longer squeeze the sealing ring 2, and the sealing ring 2 returns to its original state. The seal is released and the tube can be easily taken out.
[0037] Example 2
[0038] Combine Figure 1 、 Figure 2 Note that this embodiment replaces the original inner extrusion ring 3 with an inner extrusion ring 8 with a cylindrical support core. Other features are the same as those in Example 1, with the cylindrical support core providing radial support for the internally threaded tube 10. This allows it to withstand the greater radial sealing clamping force from the sealing ring 2 without deformation. This clamping force effectively axially constrains the end of the internally threaded tube 10, preventing the tube end from disengaging from the sealing area due to axial shortening during expansion, further improving the yield of the tube.
[0039] Example 3
[0040] Combine Figure 1 、 Figure 3 This embodiment is substantially the same as Example 1, except that the seal between the inner extrusion ring 3 and the mounting block 5 is replaced with an O-ring 9, and an O-ring groove is formed in the inner extrusion ring 3. This embodiment prevents the O-ring 9 from sliding, reducing seal wear. Furthermore, since the seal is not exposed, its lifespan is less susceptible to impurities.
[0041] Example 4
[0042] Combine Figure 1 、 Figure 4This embodiment is roughly the same as Example 2. However, it replaces the seal between the inner extrusion ring 8 with a cylindrical support core and the mounting block 5 with an O-ring 9. An O-ring groove is also provided on the inner extrusion ring 8 with a cylindrical support core. This embodiment applies radial force to the tubing, further protecting the tubing yield, while also preventing the O-ring 9 from sliding, reducing wear and tear. Furthermore, the seal is not exposed, making it less susceptible to impurities that could affect its lifespan.
[0043] Therefore, the present invention adopts the above-mentioned pipe end sealing device for internal pressure expansion of internal threaded pipes, which has a simple structure and meets the requirements of simple structure, efficient sealing, long service life, adaptability to automated production, and applicability to various product specifications.
[0044] It is worth noting that the contents not elaborated in detail in the present invention are all prior arts and are well known to those skilled in the art.
[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A pipe end sealing device for internal pressure expansion of internally threaded pipes, characterized by: It includes a mounting block, on which an extrusion sealing assembly is provided. The extrusion sealing assembly includes an inner extrusion ring, an outer extrusion ring, and a sealing ring. The outer extrusion ring is sleeved over the inner extrusion ring. The sealing ring is arranged between the outer extrusion ring and the inner extrusion ring. The outer extrusion ring is connected to the mounting block through the piston rod of the cylinder.
2. A pipe end sealing device for internal pressure expansion of an internally threaded pipe according to claim 1, characterized in that: A groove is provided on the top of the mounting block, and the shape of the groove matches the structure of the bottom of the inner extrusion ring.
3. The pipe end sealing device for internal pressure expansion of an internally threaded pipe according to claim 2, characterized in that: The side wall of the groove is provided with an internal thread, the side surface of the bottom of the inner extrusion ring is provided with an external thread matching the internal thread, and the bottom of the inner extrusion ring is placed in the groove.
4. The pipe end sealing device for internal pressure expansion of an internally threaded pipe according to claim 1, characterized in that: A sealing gasket or an O-type sealing ring is provided between the inner extrusion ring and the mounting block.
5. The pipe end sealing device for internal pressure expansion of an internally threaded pipe according to claim 1, characterized in that: A pressurizing hole is provided on the mounting block, and the pressurizing hole is communicated with the inner hole on the inner extrusion ring.
6. The pipe end sealing device for internal pressure expansion of an internally threaded pipe according to claim 1, characterized in that: The longitudinal section of the outer extrusion ring is in the shape of an "X"; the internal structure of the outer extrusion ring is consistent with the structure of the inner extrusion ring.
7. The pipe end sealing device for internal pressure expansion of an internally threaded pipe according to claim 1, characterized in that: The outer extrusion ring is provided with a through hole, the inner extrusion ring is provided with a countersunk hole, the through hole and the countersunk hole are concentric and have the same inner diameter, and the pipe end of the internal threaded pipe is placed in the through hole and the countersunk hole.
8. The pipe end sealing device for internal pressure expansion of an internally threaded pipe according to claim 1, characterized in that: The top end of the piston rod is fixedly connected to the outer extrusion ring, and the cylinder is located at the bottom end of the piston rod, and the cylinder is fixedly arranged on the mounting block.