Expansion joint forming combined die and external pressure type expansion joint

Abstract

The invention provides an expansion joint forming combined die and an external pressure type expansion joint. The expansion joint forming combined die and the external pressure type expansion joint comprise a first connecting pipe, a shell and a second connecting pipe, the first connecting pipe and the second connecting pipe are oppositely arranged, and the shell is located between the first connecting pipe and the second connecting pipe; the shell is a seamless steel pipe, and the inner walls of the two ends of the shell are provided with a first annular plate and a second annular plate correspondingly. One end of the first connecting pipe penetrates through the first annular plate and extends into the shell, and the first connecting pipe is fixedly connected with the first annular plate. According to the expansion joint forming combined die and the external pressure type expansion joint, a set of die which is thin-wall, multi-layer, small in wave pitch, high in wave height and large in wave number is adopted, so that a corrugated pipe is formed to be an elastic element, the flexibility and the elasticity are good, the annular rigidity and the axial flexibility are good, the deformation resistance is high, and the service life of the corrugated pipe is prolonged. The fatigue life of the product is greatly prolonged, and in addition, the length of the product can be guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of external pressure expansion joint technology, and particularly relates to an expansion joint forming combination mold and an external pressure expansion joint. Background Technology

[0002] Currently, expansion joints are widely used in heating network pipelines. Generally, heating network pipelines are long and have high temperatures, which naturally increases the compensation requirements of expansion joints. The requirements for expansion joints are relatively high, requiring multiple corrugated pipe sections for support. Because the external pressure expansion joint is under external pressure, the corrugated pipe is in a stretched state when the expansion joint is working, and there is no possibility of instability in the corrugated pipe. Therefore, the corrugated pipe can be hydraulically formed into multiple sections at one time. Due to the limitation of product length and the need for multiple corrugations in the corrugated pipe, it is necessary to provide a new expansion joint forming combination mold and an external pressure expansion joint to solve the above technical problems. Summary of the Invention

[0003] The technical problem solved by this invention is to provide an expansion joint forming combination mold and an external pressure expansion joint, which uses a set of molds with thin walls, multiple layers, small wave pitch, high wave height, and many wave numbers. In this way, the bellows is formed into an elastic element with good flexibility, good elasticity, good circumferential rigidity and axial flexibility, strong resistance to deformation, and greatly improves the fatigue life of the product. In addition, the product length can also be guaranteed.

[0004] To solve the above-mentioned technical problems, the expansion joint forming combination mold and external pressure expansion joint provided by the present invention include: a first connecting pipe, a shell and a second connecting pipe, wherein the first connecting pipe and the second connecting pipe are arranged opposite to each other, and the shell is located between the first connecting pipe and the second connecting pipe; The outer shell is a seamless steel pipe, and ring plate one and ring plate two are respectively installed on the inner walls of both ends of the outer shell; One end of the first connecting pipe passes through the first ring plate and extends into the outer shell, and the first connecting pipe is fixedly connected to the first ring plate.

[0005] As a further embodiment of the present invention, a support plate is provided inside the outer shell. The support plate is located between the first ring plate and the second ring plate. One end of the second connecting pipe passes through the second ring plate and extends into the outer shell to connect with the support plate. The second connecting pipe is fixedly connected to the second ring plate.

[0006] As a further embodiment of the present invention, the second connecting pipe is provided with a fixing plate, one end of the fixing plate is welded to the second ring plate, and the other end of the fixing plate is welded to the second connecting pipe.

[0007] As a further embodiment of the present invention, end rings are installed on the outer walls of the support plate and the second ring plate that are close to each other, and corrugated pipes are connected and installed on the outer walls of the support plate and the second ring plate that are close to each other.

[0008] As a further embodiment of the present invention, the outer wall of the housing is provided with lifting lugs, and the outer wall of the housing is provided with a connector, the connector being provided with a plug.

[0009] As a further embodiment of the present invention, the outer shell may be formed by rolling sheet metal and then welding it, and after welding, it shall be inspected in accordance with the JB4730-94 radiographic testing standard.

[0010] The present invention also provides an expansion joint forming combination mold, including a mold equipment. The external pressure expansion joint can be processed by the mold equipment. The mold equipment includes a base, a hollow block and a lower mold. The hollow block is fixedly installed on the top of the base. The lower mold is set on the top of the hollow block. The bottom of the lower mold extends into the hollow block. The top of the lower mold has two rows of wear-resistant cylinders.

[0011] As a further embodiment of the present invention, the mold equipment further includes a mold base, an upper mold, a mounting plate, two rows of wear-resistant cores, and two mounting blocks. The mounting plate is disposed above the top of the lower mold, the mold base is disposed at the bottom of the mounting plate, and the two mounting blocks are symmetrically mounted on the outer walls of both sides of the mold base. Both mounting blocks are fixedly connected to the bottom of the mounting plate by bolts. The upper mold is mounted at the bottom of the mold base and is adapted to the lower mold. The two rows of wear-resistant cores are symmetrically mounted at the bottom of the mold base, the upper mold is located between the two rows of wear-resistant cores, and the two rows of wear-resistant cores are adapted to the two rows of wear-resistant cylinders.

[0012] As a further embodiment of the present invention, the mold equipment further includes a top plate, a cylinder, two vertical blocks, two movable blocks, two round rods, and two buffer springs. The top plate is disposed above the top of the mounting plate. The cylinder is mounted on the top plate, and the output shaft of the cylinder is connected to the top of the mounting plate. The two vertical blocks are symmetrically mounted on the top of the base, and the tops of the two vertical blocks are fixedly connected to the bottom of the top plate. Grooves are formed on the outer walls of the two vertical blocks that are close to each other. The two movable blocks are respectively fixedly mounted on the outer walls of the two sides of the mounting plate. The two movable blocks extend into the two grooves and are slidably connected to the two grooves. The two round rods are respectively fixedly mounted in the two grooves. The round rods pass through the movable blocks and are slidably connected to the movable blocks. The two buffer springs are slidably sleeved on the two round rods. The top of the buffer spring is connected to the bottom of the movable block, and the bottom of the buffer spring is connected to the bottom inner wall of the groove.

[0013] As a further embodiment of the present invention, the mold equipment further includes a water tank, a drain pipe, a water inlet pipe, a semiconductor cooling chip assembly, multiple concave blocks, and a controller. The water tank is installed at the bottom of the base, and a water pump is installed inside the water tank. A drain pipe is installed on the base, with one end extending into the water tank and connected to the drain port of the water pump, and the other end extending into the hollow block. The water inlet pipe is installed on the base, and a valve is installed on the water inlet pipe. The top end of the water inlet pipe extends into the hollow block, and the bottom end extends into the water tank. The semiconductor cooling chip assembly is installed on the water tank, with the cold end of the semiconductor cooling chip assembly located inside the water tank and the heat dissipation end of the semiconductor cooling chip assembly located outside the water tank. Multiple concave blocks are installed inside the hollow block, with the top of each concave block connected to the bottom of the lower mold. A controller is installed on each corresponding vertical block.

[0014] Compared with related technologies, the expansion joint forming assembly mold and external pressure expansion joint provided by the present invention have the following beneficial effects: 1. This invention uses a set of molds with thin walls, multiple layers, small wave pitch, high wave height, and many wave numbers. In this way, the corrugated pipe is formed into an elastic element with good flexibility, good elasticity, good circumferential rigidity and axial flexibility, strong resistance to deformation, and greatly improves the fatigue life of the product. In addition, the product length can also be guaranteed. 2. This invention uses a cylinder drive, along with a moving block, a round rod, and a buffer spring, to achieve smooth lifting and lowering of the upper mold, ensuring stable molding pressure. The cooling component uses water circulation cooling combined with semiconductor refrigeration, which can quickly remove the heat generated during the molding process and prevent the workpiece from deforming due to high temperature. Attached Figure Description

[0015] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 This is a schematic diagram of the external pressure expansion joint of the present invention; Figure 2 This is a schematic diagram of the bellows in this invention; Figure 3 This is a schematic diagram of the structure of the mold equipment of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the structure of the mold equipment of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of the assembly of the vertical block, the moving block, the round rod, and the buffer spring in this invention.

[0017] Explanation of key symbols: In the diagram: 1. Connector 1; 2. Ring Plate 1; 3. Outer shell; 4. Support plate; 5. End ring; 6. Lifting lug; 7. Bellows; 8. Ring Plate 2; 9. Fixing plate; 10. Connector 2; 11. Connector; 12. Plug; 13. Base; 14. Hollow block; 15. Lower mold; 16. Wear-resistant cylinder; 17. Mold base; 18. Upper mold; 19. Wear-resistant core; 20. Mounting block; 21. Top plate; 22. Cylinder; 23. Vertical block; 24. Moving block; 25. Round rod; 26. Buffer spring; 27. Water tank; 28. Drain pipe; 29. ​​Inlet pipe; 30. Semiconductor cooling chip assembly; 31. Concave block; 32. Controller. Detailed Implementation

[0018] Please refer to the following: Figure 1 and Figure 2 ,in, Figure 1 This is a schematic diagram of the external pressure expansion joint of the present invention; Figure 2 This is a schematic diagram of the bellows in this invention. The expansion joint forming assembly mold and the external pressure expansion joint include: a first connecting pipe 1, a shell 3, and a second connecting pipe 10, wherein the first connecting pipe 1 and the second connecting pipe 10 are arranged opposite to each other, and the shell 3 is located between the first connecting pipe 1 and the second connecting pipe 10; The outer shell 3 is a seamless steel pipe, and the inner walls at both ends of the outer shell 3 are respectively equipped with ring plate 1 2 and ring plate 2 8; One end of the connector 1 passes through the ring plate 2 and extends into the outer casing 3, and the connector 1 is fixedly connected to the ring plate 2.

[0019] The outer shell 3 is made of seamless steel pipe, which has excellent overall pressure bearing performance and structural integrity, and can effectively resist radial deformation under external pressure. The ring plate 2 realizes a stable connection between the pipe 1 and the outer shell 3, which not only ensures the sealing of the connection and avoids media leakage, but also enhances the end structure strength and prevents local damage caused by stress concentration. The overall structure is simple and reasonable, providing an installation foundation for the subsequent addition of functional components, adapting to the basic usage requirements under external pressure conditions, and solving the problems of weak end connection and easy deformation of the outer shell in traditional expansion joints.

[0020] The outer shell 3 is provided with a support plate 4, which is located between the first ring plate 2 and the second ring plate 8. One end of the second pipe 10 passes through the second ring plate 8 and extends into the outer shell 3 to connect with the support plate 4. The second pipe 10 is fixedly connected to the second ring plate 8.

[0021] The addition of a support plate 4, which is connected to the second connecting pipe 10, forms a two-way support structure, which can effectively improve the axial load-bearing capacity of the expansion joint and prevent the second connecting pipe 10 from shifting during stress or thermal deformation. The support plate 4 rationally divides the internal space of the outer shell 3, providing a stable installation support surface for core elastic components such as the bellows 7, ensuring that the deformation trajectory of the elastic components is controllable. It further strengthens the overall structure's resistance to deformation, especially adapting to the compensation requirements of long-distance heating network pipelines, and improving the operational stability of the expansion joint under complex working conditions.

[0022] The second connecting pipe 10 is provided with a fixing plate 9. One end of the fixing plate 9 is welded to the second ring plate 8, and the other end of the fixing plate 9 is welded to the second connecting pipe 10.

[0023] The secondary welding and fixing of the connecting pipe 10 and the ring plate 8 is achieved by fixing plate 9, forming a triangular support structure, which significantly improves the shear strength and stability of the connection, effectively disperses the axial force transmitted by the connecting pipe 10, and avoids cracking of a single weld surface due to stress concentration; the welding connection method ensures sealing, prevents media penetration and corrosion of the connection, and extends the service life of the expansion joint; the structural design is simple, the processing difficulty is low, it can be mass-produced, and it meets the needs of industrial manufacturing.

[0024] Both the support plate 4 and the second ring plate 8 have end rings 5 ​​installed on their respective outer walls that are close to each other, and corrugated pipes 7 are connected and installed on the respective outer walls of the support plate 4 and the second ring plate 8 that are close to each other.

[0025] The end ring 5 provides a precise positioning and installation benchmark for the bellows 7, ensuring the coaxiality of the connection between the two ends of the bellows 7 and avoiding uneven local stress caused by installation deviations. The end ring 5 can disperse the stress transmitted by the bellows 7, preventing wear or stress concentration at the end of the bellows 7 due to direct contact with the support plate and ring plate 8, thus improving the fatigue life of the bellows 7. Combined with the bellows structure of thin-walled multi-layer, small wave pitch, high wave height and large wave number, excellent axial flexibility and circumferential rigidity can be achieved. It can not only efficiently absorb the thermal deformation of the pipeline, but also resist the risk of instability under external pressure, solving the problems of easy instability and poor deformation capacity of traditional multi-wave bellows.

[0026] The outer wall of the outer shell 3 is equipped with a lifting lug 6, and a connector 11 is installed on the outer wall of the outer shell 3. The connector 11 is provided with a plug 12.

[0027] The lifting lug 6 facilitates the handling, hoisting, and installation positioning of the expansion joint, reducing construction difficulty, improving construction efficiency, and avoiding collision damage to the shell, pipes, and other components during handling. The combined design of the connector 11 and the plug 12 allows for venting, drainage, or media sampling before installation or during operation and maintenance, ensuring the purity of the internal media of the expansion joint and preventing air or water blockage from affecting compensation performance. The plug can seal the connector, preventing media leakage during operation and improving the safety and reliability of equipment operation.

[0028] The outer shell 3 may be formed by rolling sheet metal and then welding it, and after welding, it shall be inspected according to the JB4730-94 radiographic testing standard.

[0029] The use of sheet metal roll welding to form the outer shell 3 broadens the processing technology range of the outer shell 3, especially suitable for the production of large-diameter, non-standard specification outer shells, reducing the difficulty of procuring seamless steel pipes and manufacturing costs; welding inspection according to the JB4730-94 radiographic testing standard can strictly control the welding quality, ensuring that the welded joints are free of defects such as cracks, porosity, and slag inclusions, guaranteeing the overall pressure bearing performance and sealing performance of the outer shell, reducing the risk of failure of the outer shell due to welding defects under external pressure conditions, and improving the quality stability and safety of the product.

[0030] The working principle of the external pressure expansion joint provided by this invention is as follows: First step: Under the working state, the expansion joint is subjected to external pressure, and the bellows is in a tensile state. Compared with the internal pressure expansion joint, it can effectively avoid the instability problem caused by excessive internal pressure of the bellows, and is suitable for multi-section bellows structure design. The second step: When the pipeline elongates due to the increase in operating temperature of the heating network, the corrugated pipe absorbs the displacement through its own axial flexible stretching; when the temperature decreases and the pipeline contracts, the corrugated pipe relies on elastic reset to maintain the stability of the pipeline system. At the same time, its good circumferential rigidity can ensure that no radial deformation occurs under pressure, ensuring smooth medium transportation. The third step: Welding the pipes at both ends to the ring plate and the fixing plate forms a stable load-bearing structure, which not only ensures the reliability of the connection between the expansion joint and the pipeline, but also provides stable support for the elastic deformation of the bellows, avoiding structural displacement during the deformation process.

[0031] Please refer to the following: Figures 3 to 5 The present invention also provides an expansion joint forming combination mold, including a mold equipment. The external pressure expansion joint can be processed by the mold equipment. The mold equipment includes a base 13, a hollow block 14 and a lower mold 15. The hollow block 14 is fixedly installed on the top of the base 13. The lower mold 15 is disposed on the top of the hollow block 14. The bottom of the lower mold 15 extends into the hollow block 14. Two rows of wear-resistant cylinders 16 are opened on the top of the lower mold 15.

[0032] The mold equipment also includes a mold base 17, an upper mold 18, a mounting plate, two rows of wear-resistant cores 19, and two mounting blocks 20. The mounting plate is located above the top of the lower mold 15, and the mold base 17 is located at the bottom of the mounting plate. The two mounting blocks 20 are symmetrically mounted on the outer walls of both sides of the mold base 17. Both mounting blocks 20 are fixedly connected to the bottom of the mounting plate by bolts. The upper mold 18 is mounted at the bottom of the mold base 17 and is adapted to the lower mold 15. The two rows of wear-resistant cores 19 are symmetrically mounted at the bottom of the mold base 17 and the upper mold 18 is located between the two rows of wear-resistant cores 19. The two rows of wear-resistant cores 19 are adapted to the two rows of wear-resistant cylinders 16.

[0033] The mold equipment also includes a top plate 21, a cylinder 22, two vertical blocks 23, two moving blocks 24, two round rods 25, and two buffer springs 26. The top plate 21 is located above the top of the mounting plate. The cylinder 22 is mounted on the top plate 21, and the output shaft of the cylinder 22 is connected to the top of the mounting plate. The two vertical blocks 23 are symmetrically mounted on the top of the base 13, and the tops of the two vertical blocks 23 are fixedly connected to the bottom of the top plate 21. The outer walls of the two vertical blocks 23 on the side closest to each other are provided with grooves. The two moving blocks 24 are respectively fixedly mounted on the outer walls of the two sides of the mounting plate. The two moving blocks 24 extend into the two grooves and are slidably connected to the two grooves. The two round rods 25 are respectively fixedly mounted in the two grooves. The round rods 25 pass through the moving blocks 24 and are slidably connected to the moving blocks 24. The two buffer springs 26 are slidably sleeved on the two round rods 25. The top of the buffer spring 26 is connected to the bottom of the moving block 24, and the bottom of the buffer spring 26 is connected to the bottom inner wall of the groove.

[0034] The upper mold is driven by a cylinder for lifting, enabling automated control of the molding process, improving molding efficiency, ensuring stable and controllable molding pressure, and avoiding pressure fluctuations caused by manual operation. The matching design of the moving block, round rod, and groove provides precise guidance for the lifting of the mounting plate and upper mold, preventing deviation during lifting and ensuring molding accuracy. The buffer spring effectively absorbs the impact force during the descent of the upper mold, reducing impact damage to the mold and blank, while preventing the corrugated tube blank from cracking due to a sudden increase in molding pressure, thus improving the product molding qualification rate. The overall drive and guiding structure is stable and reliable, reducing the failure rate during mold operation and extending the service life of the equipment.

[0035] The mold equipment also includes a water tank 27, a drain pipe 28, a water inlet pipe 29, a semiconductor cooling chip assembly 30, multiple concave blocks 31, and a controller 32. The water tank 27 is installed at the bottom of the base 13, and a water pump (existing technology, not shown in the figure) is installed inside the water tank 27. The drain pipe 28 is installed on the base 13, with one end extending into the water tank 27 and connected to the drain port of the water pump, and the other end extending into the hollow block 14. The water inlet pipe 29 is installed on the base 13. A valve (existing technology product, not shown in the figure) is provided on the 29. The top end of the water inlet pipe 29 extends into the hollow block 14, and the bottom end of the water inlet pipe 29 extends into the water tank 27. The semiconductor cooling chip assembly 30 is installed on the water tank 27. The cold end of the semiconductor cooling chip assembly 30 is located inside the water tank 27, and the heat dissipation end of the semiconductor cooling chip assembly 30 is located outside the water tank 27. Multiple concave blocks 31 are installed inside the hollow block 14. The top of the concave block 31 is connected to the bottom of the lower mold 15. A controller 32 is provided on the corresponding vertical block 23.

[0036] The cooling system employs a combination of water circulation cooling and semiconductor refrigeration chips to quickly remove heat generated during the molding process, preventing oxidation, deformation, or performance degradation of the blank due to high temperatures and ensuring stable mechanical properties of the corrugated pipe after molding. The cooling system allows for the recycling of cooling water, saving energy and protecting the environment. Simultaneously, the controller precisely controls the cooling temperature and rate to adapt to the molding requirements of different blank materials. The concave block further enhances the support stability of the lower mold, preventing deformation under molding pressure and cooling, thus ensuring mold precision. The controller integrates mold driving, cooling, and other functions, reducing operational difficulty, improving the automation and consistency of the molding process, and facilitating mass production.

[0037] The working principle of the expansion joint forming combination mold provided by this invention is as follows: First step: Place the corrugated pipe blank to be processed in the designated position of the lower mold 15, preset the forming parameters through the controller 32, start the equipment, the water pump in the water tank 27 starts to work, and at the same time the semiconductor cooling chip group 30 starts to cool the cooling water in the water tank. The cooling water is transported to the hollow block 14 through the drain pipe 28 to achieve the pre-cooling of the lower mold 15. The second step: The controller 32 controls the cylinder 22 to start, and the cylinder output shaft pushes the mounting plate downward. The moving blocks 24 on both sides of the mounting plate slide smoothly along the round rod 25 in the groove of the vertical block 23. The buffer spring 26 is compressed, generating a reverse buffer force to offset part of the downward impact force. As the mounting plate moves downward, the upper mold 18 at the bottom of the mold base 17 gradually approaches the lower mold 15. At the same time, the two rows of wear-resistant cores 19 are inserted into the wear-resistant cylinder 16 of the lower mold 15 to achieve precise positioning of the mold. The upper mold 18 and the lower mold 15 cooperate to extrude and form the blank. During the process, the cooling water in the hollow block 14 continuously circulates to carry away the heat generated during forming and flows back to the water tank 27 for cooling again through the water inlet pipe 29. Third step: After demolding is completed and the molding time reaches the preset time, the controller 32 controls the cylinder 22 to move in the opposite direction, driving the mounting plate to move upward, the upper mold 18 and the lower mold 15 to separate, the wear-resistant core 19 is pulled out from the wear-resistant cylinder 16, and the buffer spring 26 gradually returns to its original position; after the mounting plate rises to the initial position, the cooling system is turned off, the molded corrugated pipe workpiece is taken out, and the molding process is completed.

[0038] It should be noted that cylinder 22 is model SMC MGPM25-100, controller 32 is model Siemens S7-200 SMART SR20, and semiconductor refrigeration unit 30 is model TEC1-12706.

[0039] It should be noted that the device structure and accompanying drawings of this invention mainly describe the principle of this invention. In terms of the technical aspects of this design principle, the setting of the power mechanism, power supply system and control system of the device is not fully described. However, under the premise that those skilled in the art understand the principle of the above invention, the specific details of its power mechanism, power supply system and control system can be clearly understood. The control method in the application document is automatic control through a controller. The control circuit of the controller can be implemented by those skilled in the art through simple programming. All standard parts used can be purchased from the market, and can be customized according to the instructions and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the existing technology. The machinery, parts and equipment adopt conventional models in the existing technology, and the structure and principle of the components known to those skilled in the art can be known by those skilled in the art through technical manuals or conventional experimental methods.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments, or they can be used directly or indirectly, without departing from the principles and spirit of the invention. In other related technical fields, the scope of the invention is defined by the appended claims and their equivalents, and they are similarly included within the scope of patent protection of the invention.

Claims

1. An external pressure expansion joint, characterized in that, include: Connector 1, housing, and connector 2, wherein connector 1 and connector 2 are arranged opposite to each other, and housing is located between connector 1 and connector 2; The outer shell is a seamless steel pipe, and ring plate one and ring plate two are respectively installed on the inner walls of both ends of the outer shell; One end of the first connecting pipe passes through the first ring plate and extends into the outer shell, and the first connecting pipe is fixedly connected to the first ring plate.

2. The external pressure expansion joint according to claim 1, characterized in that: The outer shell is provided with a support plate, which is located between ring plate one and ring plate two. One end of pipe two passes through ring plate two and extends into the outer shell to connect with the support plate. Pipe two is fixedly connected to ring plate two.

3. The external pressure expansion joint according to claim 2, characterized in that: The second connecting pipe is provided with a fixing plate. One end of the fixing plate is welded to the second ring plate, and the other end of the fixing plate is welded to the second connecting pipe.

4. The external pressure expansion joint according to claim 3, characterized in that: Both the support plate and the second ring plate have end rings installed on their respective outer walls that are close to each other, and corrugated pipes are connected and installed on the respective outer walls of the support plate and the second ring plate that are close to each other.

5. The external pressure expansion joint according to claim 1, characterized in that: The outer wall of the housing is equipped with lifting lugs and a connector, and the connector is provided with a plug.

6. The external pressure expansion joint according to claim 1, characterized in that: The outer shell may be formed by rolling sheet metal and then welding it, and after welding, it shall be inspected according to the JB4730-94 radiographic testing standard.

7. A combination mold for forming expansion joints, characterized in that, The invention includes the external pressure expansion joint and mold equipment as described in claims 1 to 6. The mold equipment includes a base, a hollow block and a lower mold. The hollow block is fixedly installed on the top of the base. The lower mold is disposed on the top of the hollow block. The bottom of the lower mold extends into the hollow block. Two rows of wear-resistant cylinders are provided on the top of the lower mold.

8. The expansion joint forming assembly mold and external pressure expansion joint according to claim 7, characterized in that: The mold equipment also includes a mold base, an upper mold, a mounting plate, two rows of wear-resistant cores, and two mounting blocks. The mounting plate is positioned above the top of the lower mold, and the mold base is positioned at the bottom of the mounting plate. The two mounting blocks are symmetrically mounted on the outer walls of both sides of the mold base, and both mounting blocks are fixedly connected to the bottom of the mounting plate by bolts. The upper mold is mounted at the bottom of the mold base and is adapted to the lower mold. The two rows of wear-resistant cores are symmetrically mounted at the bottom of the mold base, and the upper mold is located between the two rows of wear-resistant cores. The two rows of wear-resistant cores are adapted to the two rows of wear-resistant cylinders.

9. The expansion joint forming assembly mold and external pressure expansion joint according to claim 8, characterized in that: The mold equipment also includes a top plate, a cylinder, two vertical blocks, two movable blocks, two round rods, and two buffer springs. The top plate is positioned above the top of the mounting plate. The cylinder is mounted on the top plate, and its output shaft is connected to the top of the mounting plate. The two vertical blocks are symmetrically mounted on the top of the base, and their tops are fixedly connected to the bottom of the top plate. Grooves are formed on the outer walls of the two vertical blocks on their adjacent sides. The two movable blocks are fixedly mounted on the outer walls of the mounting plate on both sides, extending into the two grooves and slidably connected to them. The two round rods are fixedly mounted in the two grooves, passing through the movable blocks and slidably connected to them. The two buffer springs are slidably sleeved on the two round rods, with their top ends connected to the bottom of the movable blocks and their bottom ends connected to the inner walls of the grooves.

10. The expansion joint forming assembly mold and external pressure expansion joint according to claim 9, characterized in that: The mold equipment also includes a water tank, a drain pipe, a water inlet pipe, a semiconductor cooling chip assembly, multiple concave blocks, and a controller. The water tank is installed at the bottom of the base and contains a water pump. The drain pipe is installed on the base, with one end extending into the water tank and connected to the drain port of the water pump, and the other end extending into a hollow block. The water inlet pipe is installed on the base and has a valve. The top end of the water inlet pipe extends into the hollow block, and the bottom end extends into the water tank. The semiconductor cooling chip assembly is installed on the water tank, with the cold end of the assembly located inside the water tank and the heat dissipation end located outside the water tank. Multiple concave blocks are installed inside the hollow blocks, with the top of each concave block connected to the bottom of the lower mold. A controller is installed on each corresponding vertical block.

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