A fatigue life test apparatus and method for welding a corrugated pipe

Abstract

The present application relates to the technical field of welding corrugated pipe test equipment, and specifically discloses a kind of fatigue life test equipment and method of welding corrugated pipe.The present test equipment includes body, connecting seat component, controller, gas inlet pipeline, limit seat and limit top rod;Connecting seat component includes lower connecting seat and upper connecting seat for being sealed and fixedly connected with the joint of both ends of welding corrugated pipe, and is equipped with gas pressure sensor for detecting the internal gas pressure of welding corrugated pipe;Gas inlet pipeline is equipped with electric control valve, and upper connecting seat is installed with exhaust valve, position sensor is installed on limit top rod, limit sensor, jack pin and feeding mechanism are installed on limit seat.The present test equipment is simple in structure, can significantly improve working life and operating energy efficiency;It has air tightness detection function, and when air tightness detection is carried out, welding corrugated pipe does not need to be disassembled, which is convenient and efficient, time-saving and efficient;The present test equipment is ingenious and reasonable in structure, stable in performance, easy to implement, and low in manufacturing and operating cost.

Description

Technical Field

[0001] This invention relates to the field of welding bellows testing equipment, and in particular to a fatigue life testing device and method for welding bellows. Background Technology

[0002] Welded bellows, as elastic elements combining high-precision sealing and motion transmission, play an irreplaceable role in high-end manufacturing fields such as aerospace, vacuum equipment, and precision instruments. Fatigue life is a crucial indicator for evaluating the quality and performance of welded bellows, requiring fatigue life testing equipment for relevant tests. Currently, there are various types and styles of fatigue life testing equipment for welded bellows, but most employ mechanical reciprocating transmission mechanisms to drive the bellows in reciprocating expansion and contraction. The complex structure of these mechanical reciprocating transmission mechanisms, coupled with the need to accommodate adjustable expansion and contraction, results in cumbersome equipment structures and large space requirements. Furthermore, the mechanical reciprocating transmission mechanisms experience significant transmission losses and mechanical wear during operation, leading to short equipment lifespans, low energy efficiency, and high testing costs. In addition, during testing, airtightness checks are required to determine if the welded bellows is damaged, typically necessitating the use of other equipment. The disassembly and assembly of the welded bellows are cumbersome, significantly reducing the overall efficiency of fatigue life testing. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a fatigue life testing device for welded bellows. It uses high-pressure gas to drive the welded bellows to extend and relies on the rebound force of the welded bellows itself and the gravity of its related components to retract. This eliminates the need for a mechanical reciprocating transmission mechanism. The overall structure of the testing device is very simple, the performance is stable, the energy consumption is low, and it also has an airtightness testing function.

[0004] On the other hand, the present invention also provides a method for fatigue life testing of welded bellows based on the fatigue life testing equipment.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0006] A fatigue life testing device for welded corrugated pipes includes a body, a connecting seat assembly, and a controller. The body is equipped with a guide rod, an air inlet pipe, and a limiting seat. The guide rod is fixed to the body and extends vertically. The connecting seat assembly includes a lower connecting seat fixed to the body and an upper connecting seat slidably connected to the guide rod. A pressure sensor is installed in the connecting seat assembly. One end of the air inlet pipe communicates with the interior of the welded corrugated pipe, and the other end is connected to a high-pressure air source device, and is equipped with an electrically controlled valve. An exhaust valve is installed on the upper connecting seat, and the exhaust valve has a valve stem with a valve plate fixed to it. When the valve stem moves upward, the exhaust valve will reach a cutoff point. In the stopped state, the valve stem moves downward, and the exhaust valve will reach the open state; a telescopic limit rod is fixed in the lower connecting seat, and a position sensor is installed on the limit rod; when the upper connecting seat moves to the lower end of the stroke, the valve stem is limited by the limit rod, so that the exhaust valve reaches the closed state; the limit seat is equipped with a limit sensor, a top pin, and a feeding mechanism, and the top pin has an upper position and a lower position; when the top pin is in the lower position, and the upper connecting seat is at the upper end of the stroke, the valve stem abuts against the top pin, so that the exhaust valve reaches the open state; when the top pin is in the upper position, and the upper connecting seat is at the upper end of the stroke, the upper end of the valve stem does not contact the top pin.

[0007] In a preferred embodiment, there are two guide rods, and the upper ends of the two guide rods are fixedly connected by a connecting arm to form a gantry structure.

[0008] In a preferred embodiment, the upper connecting seat is fixed with a guide sleeve that mates with each guide rod. The guide sleeve is fitted onto the corresponding guide rod and the two slide together.

[0009] In a preferred embodiment, a side hole is provided on the side wall of the exhaust valve, and the valve cavity of the exhaust valve is connected to the outside through the side hole. A valve cover is fixed at the upper end of the exhaust valve, and a vertically extending guide tube is fixed on the valve cover. The valve stem passes through the guide tube and the two are slidably engaged. A limiting boss is provided on the valve stem, and the limiting boss is located above the guide tube.

[0010] In a preferred embodiment, the position sensor is a contact sensor, installed on the upper end of the limiting rod and directly opposite the lower end of the valve stem; during the downward movement of the upper connecting seat, the valve stem is pushed by the position sensor to make the exhaust valve reach the shut-off state.

[0011] In a preferred embodiment, the limiting seat is fixed with a sliding sleeve that mates with the guide rods one by one. The sliding sleeve is sleeved on the corresponding guide rod and the two slide in cooperation. A locking element is installed on the sliding sleeve.

[0012] In a preferred embodiment, the limiting seat has a vertically extending groove, the top pin is located in the groove and is slidably engaged, and the upper end of the top pin has a downwardly extending screw hole; the feeding mechanism includes a drive motor whose working state is controlled by a controller, the drive motor is fixed on the limiting seat and the output shaft is connected to a screw rod, and the screw rod is threadedly engaged with the screw hole.

[0013] In a preferred embodiment, the limit sensor is a contact sensor with its sensing end located on the lower side of the limit seat. When the upper connecting seat reaches the upper end of its travel, the sensor can make direct or indirect contact with the upper connecting seat to prompt the limit sensor to send a signal to the controller.

[0014] In a preferred embodiment, the air pressure sensor is installed and fixed in the lower connecting seat, and the controller, air intake pipe, and electric control valve are installed on the machine body; the lower connecting seat has an air intake hole, one end of the air intake pipe is connected to the inside of the welded corrugated pipe through the air intake hole, and the other end of the air intake pipe is connected to an air intake connector; the air intake connector is fixed on the outer wall of the machine body.

[0015] In a preferred embodiment, the upper connecting seat is disc-shaped, with several counterweight rings placed on its upper side.

[0016] In a preferred embodiment, the controller is mounted on the machine body, the guide rod is a tubular structure, and a terminal block electrically connected to the drive mechanism and the limit sensor is fixed on the limit seat. A wire is connected to the terminal block, and the other end of the wire extends through the inside of the guide rod into the machine body and is connected to the controller. A spring-type telescopic section is provided at the end of the wire connected to the terminal block.

[0017] In a preferred embodiment, the controller is installed in the machine body. The limit seat is fixed with a terminal block electrically connected to the drive mechanism and the limit sensor and a probe arm protruding outward. The terminal block is connected to the controller via a wire. The wire is supported by the probe arm and extends from the outside of the upper and lower connecting seats. The part of the wire located on the lower side of the probe arm is provided with a spring-type telescopic section.

[0018] A fatigue life testing method for welded bellows, comprising the following steps, using the fatigue life testing equipment to perform fatigue testing on the welded bellows:

[0019] Step 1: Adjust the stroke range of the upper connecting seat according to the expansion and contraction test requirements of the welded corrugated pipe;

[0020] Adjust the positions of the lower and upper ends of the upper connecting seat's stroke so that when the upper connecting seat is at the lower end of the stroke, the length of the welded bellows under test is consistent with the minimum length required for the test in the contracted state, and when the upper connecting seat is at the upper end of the stroke, the length of the welded bellows under test is consistent with the maximum length required for the test in the extended state.

[0021] Step 2: Install and fix the welded corrugated pipe;

[0022] The joints at both ends of the welded bellows are sealed and fixedly connected to the lower connecting seat and the upper connecting seat, respectively.

[0023] Step 3: Drive the welded bellows to perform reciprocating telescopic motion;

[0024] When the testing equipment is started, the controller adjusts the top pin to the upper position; when the upper connecting seat moves to the lower end of the stroke, the controller adjusts the solenoid valve to the open position; when the upper connecting seat moves to the upper end of the stroke, the controller adjusts the solenoid valve to the closed position; thus, the welded bellows performs reciprocating extension and retraction motion.

[0025] Step 4: Perform an airtightness test on the welded bellows;

[0026] When the controller adjusts the top pin to the upper working position and the upper connecting seat moves to the upper end of the stroke, the controller adjusts the electric control valve to the cut-off state. The controller detects the internal air pressure of the welded bellows based on the air pressure sensor to determine whether the welded bellows is damaged.

[0027] Compared with the prior art, the fatigue life testing equipment for welded bellows in this invention has the following beneficial technical effects:

[0028] 1. This testing equipment does not have a complex mechanical reciprocating transmission mechanism and reduction mechanism, which not only simplifies the overall structure of the testing equipment, but also significantly improves its working life and operating efficiency by avoiding a large amount of mechanical friction.

[0029] 2. This testing equipment uses high-pressure gas to drive the welded bellows to reciprocate and extend, and the extension and retraction amount is adjustable. Based on the structure that achieves the above functions, the airtightness testing function is realized without significantly increasing the cost, making the testing equipment more functional and reducing the overall cost. More significantly, the welded bellows does not need to be disassembled during the airtightness test, and the testing operation can be carried out without interruption, which is convenient, fast, time-saving and efficient.

[0030] 3. The overall structure of this testing equipment is ingenious and reasonable. It is powered by high-pressure gas in one direction, and the exhaust valve can automatically adjust its on / off state according to the stroke change without the need for a complex reversing mechanism. It has stable performance, is easy to implement, and has low manufacturing and operating costs. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0032] Figure 1This is one of the overall structural schematic diagrams of the fatigue life testing equipment in this invention.

[0033] Figure 2 This is the second schematic diagram of the overall structure of the fatigue life testing equipment in this invention.

[0034] Figure 3 This is a schematic diagram of the mating structure of the upper connecting seat and the exhaust valve in this invention.

[0035] Figure 4 This is a schematic diagram of the upper side of the limiting seat in this invention.

[0036] Figure 5 This is a schematic diagram of the structure of the lower side of the limiting seat in this invention.

[0037] Figure 6 This is a schematic diagram of the top pin and the feeding mechanism in this invention.

[0038] Figure 7 This is a schematic diagram of the air path and circuit connection status in the fatigue life testing equipment of the present invention.

[0039] Figure 8 This is a schematic diagram showing the connection between the fatigue life testing equipment and the welded bellows in this invention.

[0040] Figure 9 This is a schematic diagram showing the state of the upper connector when it reaches the lower end of its stroke during the test.

[0041] Figure 10 This is a schematic diagram showing the state of the welded bellows being stretched by high-pressure gas during the test.

[0042] Figure 11 This is a schematic diagram showing the state of the upper connector when it reaches the upper end of its travel during the test.

[0043] Figure 12 This is a schematic diagram showing the state of the exhaust valve when the upper connecting seat reaches the upper end of its stroke during the test.

[0044] Figure 13 This is a schematic diagram showing the shrinkage state of the welded bellows during the test.

[0045] Figure 14 This is a schematic diagram showing the state of the exhaust valve when the welded bellows contracts during the test.

[0046] Figure 15 This is a schematic diagram of the fatigue life testing equipment in the airtightness testing mode of the present invention.

[0047] Figure 16 This is a schematic diagram showing the interaction between the top pin and the exhaust valve under airtightness testing mode.

[0048] Figure 17This is a schematic diagram of the structure in which the wire extends inside the guide rod.

[0049] Figure 18 This is a schematic diagram showing the conductor being supported and guided by the probe arm.

[0050] In the diagram: 1. Body, 2. Controller, 3. Lower connecting seat, 4. Pressure sensor, 5. Position sensor, 6. Guide rod, 7. Exhaust valve, 8. Valve stem, 9. Locking element, 10. Drive motor, 11. Connecting arm, 12. Limit seat, 13. Limit sensor, 14. Sliding sleeve, 15. Upper connecting seat, 16. Guide sleeve, 17. Limiting top rod, 18. Air inlet, 19. Air inlet connector, 20. Valve plate, 21. Counter, 22. Top pin, 23. Side hole, 24. Guide tube, 25. Valve cover, 26. Limiting boss, 27. Sealing gasket, 28. Terminal block, 29. Screw hole, 30. Slide groove, 31. Screw, 32. Air inlet pipe, 33. Electric control valve, 34. Connector, 35. Counterweight ring, 36. Wire, 37. Probe arm. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0052] See Figure 1 , Figure 2 , Figure 7 , Figure 8As shown in the embodiment, a fatigue life testing device for welded corrugated pipes is disclosed, which includes a body 1, a connecting seat assembly, and a controller 2; the body 1 is equipped with guide rods 6, an air inlet pipe 32, and a limiting seat 12; the guide rods 6 are one or more, fixed to the body 1 and extending vertically upward; the connecting seat assembly includes a lower connecting seat 3 and an upper connecting seat 15, which can be sealed and fixedly connected to the joints 34 at both ends of the welded corrugated pipe, respectively, and seal both ends of the welded corrugated pipe; The lower connecting seat 3 is fixed to the body 1, and the upper connecting seat 15 is slidably connected to the guide rod 6, allowing it to move up and down. Thus, the upper connecting seat 15 can move up and down with the extension and retraction of the welded bellows. Simultaneously, the upper connecting seat 15 also provides guidance for the extension and retraction of the welded bellows, preventing deviation during the extension and retraction process and improving testing accuracy. A pressure sensor 4 is installed in the connecting seat assembly to detect the internal pressure of the welded bellows and feeds the signal back to the controller 2. One end of the air inlet pipe 32 is connected to the inside of the welded bellows via the connecting seat assembly, and the other end is connected to a high-pressure gas source. An electrically controlled valve 33 is installed on the air inlet pipe 32 to adjust its on / off state. Based on this configuration, high-pressure gas can be injected into the welded bellows to drive its extension. The working state of the electrically controlled valve 33 is controlled by the controller 2; either a solenoid valve or an electric valve can be used.

[0053] See Figures 1-3 As shown, an exhaust valve 7 is fixedly installed on the upper connecting seat 15. The lower end of the exhaust valve 7 has a valve port communicating with the valve cavity. The valve cavity is connected to the inside of the welded bellows through the valve port, and the valve cavity is also connected to the outside atmosphere on the upper side of the upper connecting seat 15. A vertically extending valve stem 8 is provided in the exhaust valve 7. The upper and lower ends of the valve stem 8 extend to the top and bottom of the exhaust valve 7, respectively. The valve stem 8 slides with the exhaust valve 7 and can move up and down. A valve plate 20 is fixed on the valve stem 8. The valve plate 20 is located on the lower side of the valve port. When the valve stem 8 moves upward, the valve plate 20 will press against the valve. The valve stem 8 blocks the valve port by resting against the lower side, thus putting the exhaust valve 7 into a closed state, meaning that the inside of the welded bellows cannot communicate with the outside through the exhaust valve 7. When the valve stem 8 moves downward, the valve plate 20 separates from the valve port, putting the exhaust valve 7 into an open state, and the opening degree of the exhaust valve 7 gradually increases as the valve stem 8 moves downward. Since the valve plate 20 and the valve stem 8 always maintain a downward trend based on their own weight, the exhaust valve 7 can be regarded as a self-operated normally open valve. When the external force cannot overcome the gravity of the valve plate 20 and the valve stem 8, the exhaust valve 7 will automatically reset to the fully open state.

[0054] See Figure 1 , Figure 2 , Figure 7 , Figure 9As shown, a vertically extending limiting rod 17 is fixed in the lower connecting seat 3. The limiting rod 17 is located directly below the valve stem 8. A position sensor 5 is installed on the limiting rod 17. The limiting rod 17 is a telescopic structure, making its upper end and the height of the position sensor 5 adjustable. During the process of the upper connecting seat 15 moving downward as the welded bellows contracts, the valve stem 8 is limited by the limiting rod 17 and cannot continue to move downward. The exhaust valve 7 will gradually reach the cut-off state. At this time, the lower connecting seat 3 cannot continue to move downward, that is, it reaches the lower end of the stroke, and the welded bellows contracts to its minimum length. Based on the above-mentioned cooperation structure, the position of the lower end of the stroke of the upper connecting seat 15 can be adjusted by adjusting the height of the upper end of the limiting rod 17. The controller 2 determines whether the lower connecting seat 3 has reached the lower end of the stroke based on the signal fed back by the position sensor 5.

[0055] See Figure 1 , Figure 2 , Figures 4-7 As shown, the limiting seat 12 is located above the upper connecting seat 15 and its height is adjustable. A limiting sensor 13, a top pin 22, and a feeding mechanism are installed on the limiting seat 12. The top pin 22 is slidably connected to the limiting seat 12 and is located directly above the valve stem 8. The top pin 22 has two working states: an upper working position and a lower working position. The top pin 22 is driven by the feeding mechanism and can switch between working positions. The limiting sensor 13 cooperates with the controller 2 to limit the upper end of the stroke of the upper connecting seat 15. Specifically, when the upper connecting seat 15 moves upward to the upper end of its stroke as the welding bellows extends, the controller 2 adjusts the solenoid valve 33 to the cut-off state, that is, stops the injection of high-pressure gas into the welding bellows. After this, the welding bellows cannot continue to extend, meaning the upper connecting seat 15 cannot move upward after reaching the upper end of its stroke. Based on the above mechanism, the position of the upper end of the stroke of the upper connecting seat 15 can be adjusted by adjusting the height of the limiting seat 12. Figure 11 , Figure 12 As shown, when the top pin 22 is in the lower position, during the process of the upper connecting seat 15 moving to the upper end of its stroke, the upper end of the valve stem 8 cannot move further upward after it abuts against the top pin 22. When the upper connecting seat 15 moves to the upper end of its stroke, the exhaust valve 7 reaches the open state; as Figure 15 , Figure 16 As shown, when the top pin 22 is in the upper position, this fatigue life testing equipment enters the airtightness testing mode. When the upper connecting seat 15 moves to the upper end of the stroke, the upper end of the valve stem 8 does not contact the top pin 22.

[0056] The testing method and working principle of this fatigue life testing equipment for welded bellows are as follows:

[0057] 1. Adjust the stroke range of the upper connecting seat 15 according to the expansion and contraction test requirements of the welded corrugated pipe.

[0058] Based on the above structure, it can be determined that the stroke range of the upper connecting seat 15 determines the expansion and contraction of the welded bellows. Therefore, by adjusting the stroke range of the upper connecting seat 15 accordingly, it can be ensured that the expansion and contraction of the welded bellows meets the test requirements during the test; specifically, as shown... Figure 9 As shown, by adjusting the height of the upper end of the limiting rod 17, the position of the lower end of the stroke of the upper connecting seat 15 is adjusted to ensure that when the upper connecting seat 15 is at the lower end of the stroke, the length of the welded bellows under test is consistent with the minimum length required for the test under the contracted state; similarly, as Figure 11 As shown, by adjusting the height of the limit seat 12, the position of the upper end of the stroke of the upper connecting seat 15 is adjusted to ensure that when the upper connecting seat 15 is at the upper end of the stroke, the length of the welded bellows under test is consistent with the maximum length required for the test in the extended state.

[0059] 2. Install and fix the welded corrugated pipe.

[0060] like Figure 8 As shown, the welded bellows is placed vertically between the lower connecting seat 3 and the upper connecting seat 15, and the limiting rod 17 is located inside the welded bellows; the joints 34 at both ends of the welded bellows are sealed and fixedly connected to the lower connecting seat 3 and the upper connecting seat 15 respectively using bolts and other connecting parts.

[0061] 3. Drive the welded bellows to perform reciprocating expansion and contraction motion.

[0062] Connect the intake pipe 32 to a high-pressure air source device such as an electric air pump, and start the test equipment; the controller 2 adjusts the top pin 22 to the upper working position based on the feeding mechanism, and the top pin 22 maintains the upper working position during the test; the test equipment operates under the coordinated operation of the controller 2, the electric control valve 33, the position sensor 5, and the limit sensor 13. Figure 7 , Figure 9 , Figure 10 As shown, when the upper connecting seat 15 moves to the lower end of its stroke, the welded bellows retracts to its minimum length, and the exhaust valve 7 switches to the closed state. At this time, the controller 2 adjusts the solenoid valve 33 to the open state, and high-pressure gas enters the welded bellows, driving the welded bellows to extend. During this process, because the inside of the welded bellows is under high pressure, the valve plate 20 can be forced to press tightly against the valve port, thereby keeping the exhaust valve 7 in the closed state. Figure 7 , Figure 11 , Figure 12 As shown, when the upper connecting seat 15 moves to the upper end of its stroke, the welded bellows extends to its maximum length, and the exhaust valve 7 switches to the open state. At this time, the controller 2 adjusts the solenoid valve 33 to the shut-off state, that is, stops the injection of high-pressure gas into the welded bellows; thereafter, as... Figure 13 , Figure 14As shown, the welded bellows will retract downwards based on its own rebound force and the gravity of components such as the upper connecting seat 15. During the retraction of the welded bellows, the valve plate 20 and the valve stem 8 will slide downwards based on their own weight, causing the exhaust valve 7 to automatically reset to its maximum opening, i.e., fully open, so that the gas inside the welded bellows can be discharged in time as it contracts, thereby increasing the contraction rate of the welded bellows. Thus, by performing reciprocating expansion and contraction motion of the welded bellows in the above manner, the purpose of fatigue life testing can be achieved.

[0063] 4. Perform an airtightness test on the welded corrugated pipe.

[0064] like Figure 7 , Figure 15 , Figure 16 As shown, according to the test requirements, when performing an airtightness test on the welded bellows, the controller 2 adjusts the top pin 22 to the upper position based on the feeding mechanism, and the test equipment enters the airtightness test mode. When the upper connecting seat 15 moves upward to the upper end of its stroke as the welded bellows extends, the controller 2 adjusts the solenoid valve 33 to the shut-off state. Since the top pin 22 is in the upper position and cannot contact the valve stem 8, the exhaust valve 7 remains in the shut-off state. At this time, the inside of the welded bellows is in a sealed high-pressure state. The controller 2 detects the internal air pressure of the welded bellows based on the air pressure sensor 4. If the air pressure is stable, it indicates that the welded bellows is not damaged. If the test needs to continue, the controller 2 adjusts the top pin 22 to the lower position based on the feeding mechanism. The top pin 22 pushes the valve stem 8 downward, causing the exhaust valve 7 to switch to the open state, thereby restoring normal operation. If the air pressure gradually decreases, it indicates that the welded bellows has a leak and is damaged, and the test should be terminated.

[0065] This testing equipment uses high-pressure gas to drive the extension of a welded bellows. The welded bellows then retracts using its own resilience and the gravity of other components, thus achieving reciprocating extension and retraction. This eliminates the need for complex mechanical reciprocating transmission and reduction mechanisms, simplifying the overall structure of the testing equipment and significantly improving its service life and operational efficiency by avoiding a large amount of mechanical friction.

[0066] This testing equipment utilizes high-pressure gas to drive the welded bellows in a reciprocating expansion and contraction motion, enabling fatigue life testing and convenient and quick adjustment of the expansion and contraction amount. Furthermore, based on the structure that achieves the above functions, airtightness testing is implemented without significantly increasing costs, thus enhancing the equipment's functionality and reducing overall cost. More significantly, airtightness testing does not require disassembly of the welded bellows, allowing for uninterrupted testing operations, making it convenient, fast, time-saving, and highly efficient.

[0067] The overall structure of this testing equipment is ingenious and reasonable. It is powered by high-pressure gas in one direction, and the exhaust valve can automatically adjust its on / off state according to the stroke change without the need for a complex reversing mechanism. It is easy to implement, has low manufacturing and operating costs, and high stability.

[0068] Preferred, such as Figure 1 , Figure 2 As shown, there are two guide rods 6. The upper ends of the two guide rods 6 are fixedly connected by a connecting arm 11 to form a gantry structure, so as to improve the simplicity of the device and ensure that the guide rods 6 have good stability.

[0069] In the prior art, the joint 34 of the welded bellows product has a variety of structural designs, such as flanges or threaded heads; correspondingly, the lower connecting seat 3 and the upper connecting seat 15 have a variety of structural designs, such as flange seats or threaded seats, to adapt to the structure of the joint 34 of the welded bellows; at the same time, sealing rings, sealing gaskets 27 and other sealing elements can be provided on the lower connecting seat 3 and the upper connecting seat 15 to ensure the sealing performance of the connection between the lower connecting seat 3, the upper connecting seat 15 and the welded bellows joint 34.

[0070] Specifically, such as Figure 1 , Figure 2 As shown, a plurality of guide sleeves 16 are fixed on the upper connecting seat 15. The guide sleeves 16 are matched with the guide rods 6 one by one. The guide sleeves 16 are sleeved on the corresponding guide rods 6 and the two are slidably matched.

[0071] Specifically, such as Figure 1 , Figure 3 As shown, a side hole 23 is provided on the side wall of the exhaust valve 7. The side hole 23 is located above the upper connecting seat 15. The valve cavity of the exhaust valve 7 is connected to the outside through the side hole 23. A valve cover 25 is fixed at the upper end of the exhaust valve 7. A vertically extending guide tube 24 is fixed on the valve cover 25. The valve stem 8 passes through the guide tube 24 and the two slide together. A limiting boss 26 is provided on the valve stem 8. The limiting boss 26 is located above the guide tube 24 to limit the stroke of the valve stem 8 and prevent the valve stem 8 from moving downward and slipping out of the guide tube 24.

[0072] Preferably, the position sensor 5 is a contact sensor, installed on the upper end of the limiting rod 17 and directly opposite the lower end of the valve stem 8. During the downward movement of the upper connecting seat 15, the valve stem 8 is pushed by the position sensor 5 to make the exhaust valve 7 reach the closed state. At the same time, after the position sensor 5 contacts the valve stem 8, it sends a signal back to the controller 2. Since the upper connecting seat 15 has not reached the lower end of its stroke when the position sensor 5 contacts the valve stem 8, it can continue to move downward a certain distance until the exhaust valve 7 reaches the closed state. Therefore, after receiving the signal generated by the contact between the position sensor 5 and the valve stem 8, the controller 2 should delay for a certain period of time before adjusting the solenoid valve 33 to the open state to ensure that the upper connecting seat 15 can reach the lower end of its stroke, thereby improving the accuracy of the operating parameters of the test equipment and ensuring that the exhaust valve 7 can reach the closed state, thus improving the stability of the test equipment operation.

[0073] Specifically, such as Figure 1 , Figure 2 As shown, the limiting seat 12 is fixed with a sliding sleeve 14 that cooperates with the guide rod 6 one by one. The sliding sleeve 14 is sleeved on the corresponding guide rod 6 and the two slide in cooperation. The sliding sleeve 14 is provided with locking parts such as bolts 9 to lock the sliding sleeve 14 and the guide rod 6.

[0074] Preferred options, see Figure 5 , Figure 6 As shown, a vertically extending slide groove 30 is provided on the limiting seat 12, and the top pin 22 is located in the slide groove 30 and is slidably engaged. The upper end of the top pin 22 is provided with a downwardly extending screw hole 29. The feeding mechanism includes a drive motor 10, which is mounted and fixed on the limiting seat 12 and has an output shaft connected to a screw 31. The screw 31 extends into the screw hole 29 and the two are threadedly engaged. The working state of the drive motor 10 is controlled by the controller 2. Thus, the drive motor 10 can drive the top pin 22 to move up and down, and the controller 2 can adjust the position of the top pin 22 based on the control of the drive motor 10. The drive motor 10 can be a micro stepper motor to improve the controllability of the position of the top pin 22.

[0075] Preferably, the limit sensor is a contact sensor with its sensing end located on the lower side of the limit seat 12. When the upper connecting seat 15 reaches the upper end of its travel, it can make direct or indirect contact with the upper connecting seat 15 to prompt the limit sensor to send a signal to the controller 2.

[0076] Preferred options, see Figure 1 , Figure 7As shown, the air pressure sensor 4 is installed and fixed in the lower connecting seat 3, and the controller 2, air inlet pipe 32, and electric control valve 33 are installed inside the body 1; an air inlet hole 18 is opened in the lower connecting seat 3, one end of the air inlet pipe 32 is connected to the inside of the welded corrugated pipe through the air inlet hole 18, and the other end of the air inlet pipe 32 is connected to an air inlet connector 19; the air inlet connector 19 is fixed on the outside of the body 1 to facilitate connection with high-pressure air source equipment.

[0077] When performing testing using the testing equipment disclosed in this invention, refer to... Figure 13 As shown, during the downward movement of the upper connecting seat 15, the welded bellows contracts. The power for this process comes from the rebound force of the welded bellows itself and the gravity of components such as the upper connecting seat 15 and the exhaust valve 7. This makes the downward movement speed of the upper connecting seat 15 unadjustable, and may even result in the upper connecting seat 15 failing to reach the lower end of its stroke. Based on the above situation, the solution of the present invention is as follows:

[0078] like Figure 9 As shown, the upper connecting seat 15 is disc-shaped, with several annular counterweight rings 35 placed on its upper side. Thus, when this testing equipment is working, the number of counterweight rings 35 can be adjusted according to the operating needs to regulate the weight on the upper side of the upper connecting seat 15, thereby controlling the speed of the downward movement of the upper connecting seat 15, improving testing efficiency, and avoiding the situation where the upper connecting seat 15 cannot reach the lower end of its stroke.

[0079] In the testing equipment disclosed in this invention, the controller 2 can statistically determine the number of reciprocating movements of the connecting seat 15 based on signals fed back from components such as the position sensor 5 and the limit sensor 13, thus obtaining the number of expansion and contraction cycles of the welded corrugated pipe; simultaneously, as Figure 2 , Figure 5 , Figure 7 As shown, the accuracy of recording the number of times the welded bellows expands and contracts can also be further improved by installing a counter 21. The counter 21 can be installed on the limit seat 12 or the limit rod 17.

[0080] In this invention, the drive mechanism, limit sensor 13, and controller 2 need to be electrically connected via wire 36. To improve the structural simplicity of the testing equipment and avoid interference from the wire 36 to the movement of other components, this invention provides two specific ways of setting the wire 36:

[0081] One is: See Figure 1 , Figure 4 , Figure 17As shown, the controller 2 is installed in the body 1. The guide rod 6 is a hollow tubular structure. A terminal block 28 is fixed on the limiting seat 12. The terminal block 28 is electrically connected to the drive mechanism and the limiting sensor 13. A wire 36 is connected to the terminal block 28. The other end of the wire 36 extends through the inside of the guide rod 6 into the body 1 and connects to the controller 2. The end of the wire 36 connected to the terminal block 28 is provided with a spring-type telescopic section, so that the wire 36 can extend and retract as the limiting seat 12 is adjusted up and down. Based on this design, the vertical extension part of the wire 36 is hidden in the guide rod 6, making the external structure of the testing equipment simpler, while avoiding interference from the wire 36 to the movement of the upper connecting seat 15 and the welded corrugated pipe.

[0082] The second is: such as Figure 7 , Figure 18 As shown, the controller 2 is installed in the body 1. A terminal block 28 and a probe arm 37 extending outward are fixed on the limiting seat 12. The terminal block 28 is electrically connected to the drive mechanism and the limiting sensor 13. The terminal block 28 is connected to the controller 2 via a wire 36. The wire 36 is supported by the probe arm 37 and extends from the outside of the upper connecting seat 15 and the lower connecting seat 3, thereby preventing interference with the movement of components such as the upper connecting seat 15 and the welded corrugated pipe. The portion of the wire 36 located below the probe arm 37 is provided with a spring-type telescopic section, so that the wire 36 can extend and retract as the upper and lower positions of the limiting seat 12 are adjusted.

Claims

1. A fatigue life testing device for welded bellows, comprising a body, a connecting seat assembly, and a controller; characterized in that: The machine body is equipped with a guide rod, an air intake pipe, and a limiting seat; the guide rod is fixed to the machine body and extends vertically; the connecting seat assembly includes a lower connecting seat fixed to the machine body and an upper connecting seat slidably connected to the guide rod; a pressure sensor is installed in the connecting seat assembly; one end of the air intake pipe is connected to the inside of a welded corrugated pipe, and the other end is connected to a high-pressure air source device, and is equipped with an electrically controlled valve; an exhaust valve is installed on the upper connecting seat, and the exhaust valve has a valve stem with a valve plate fixed on the valve stem; when the valve stem moves upward, the exhaust valve will reach the closed state, and when the valve stem moves downward, the exhaust valve will reach the open state. In the open state; a telescopic limit rod is fixed in the lower connecting seat, and a position sensor is installed on the limit rod; when the upper connecting seat moves to the lower end of the stroke, the valve stem is limited by the limit rod, causing the exhaust valve to reach the closed state; the limit seat is equipped with a limit sensor, a top pin, and a feeding mechanism, and the top pin has an upper position and a lower position; when the top pin is in the lower position and the upper connecting seat is at the upper end of the stroke, the valve stem abuts against the top pin, causing the exhaust valve to reach the open state; when the top pin is in the upper position and the upper connecting seat is at the upper end of the stroke, the upper end of the valve stem does not contact the top pin.

2. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The guide rod is provided in two parts, and the upper ends of the two guide rods are fixedly connected by a connecting arm to form a gantry structure.

3. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The upper connecting seat is fixed with a guide sleeve that mates with each guide rod. The guide sleeve is fitted onto the corresponding guide rod and the two slide together.

4. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The exhaust valve has a side hole on its side wall, and the valve chamber of the exhaust valve is connected to the outside through the side hole. A valve cover is fixed at the upper end of the exhaust valve, and a vertically extending guide tube is fixed on the valve cover. The valve stem passes through the guide tube and the two slide together. A limiting boss is provided on the valve stem, and the limiting boss is located above the guide tube.

5. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The position sensor is a contact sensor, installed on the upper end of the limit rod, and directly opposite the lower end of the valve stem.

6. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The limiting seat is fixed with a sliding sleeve that mates with the guide rods one by one. The sliding sleeve is sleeved on the corresponding guide rod and the two slide in cooperation. A locking element is installed on the sliding sleeve.

7. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The limiting seat has a vertically extending slide groove, the top pin is located in the slide groove and is slidably engaged, and the upper end of the top pin has a downwardly extending screw hole; the feeding mechanism includes a drive motor whose working state is controlled by a controller, the drive motor is fixed on the limiting seat and the output shaft is connected to a screw rod, and the screw rod is threadedly engaged with the screw hole.

8. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The limit sensor is a contact sensor with its sensing end located on the lower side of the limit seat. When the upper connecting seat reaches the upper end of its travel, it can make direct or indirect contact with the upper connecting seat to prompt the limit sensor to send a signal back to the controller.

9. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The upper connecting seat is disc-shaped, with several counterweight rings placed on its upper side.

10. A method for testing the fatigue life of a welded bellows, characterized in that: The fatigue life testing of the welded bellows using the fatigue life testing equipment according to any one of claims 1-9 includes the following steps: Step 1: Adjust the stroke range of the upper connecting seat according to the expansion and contraction test requirements of the welded corrugated pipe; Adjust the positions of the lower and upper ends of the upper connecting seat's stroke so that when the upper connecting seat is at the lower end of the stroke, the length of the welded bellows under test is consistent with the minimum length required for the test in the contracted state, and when the upper connecting seat is at the upper end of the stroke, the length of the welded bellows under test is consistent with the maximum length required for the test in the extended state. Step 2: Install and secure the welded corrugated pipe; The joints at both ends of the welded bellows are sealed and fixedly connected to the lower connecting seat and the upper connecting seat, respectively. Step 3: Drive the welded bellows to perform reciprocating telescopic motion; When the testing equipment is started, the controller adjusts the top pin to the upper position; when the upper connecting seat moves to the lower end of the stroke, the controller adjusts the solenoid valve to the open position; when the upper connecting seat moves to the upper end of the stroke, the controller adjusts the solenoid valve to the closed position; thus, the welded bellows performs reciprocating extension and retraction motion. Step 4: Perform an airtightness test on the welded bellows; When the controller adjusts the top pin to the upper working position and the upper connecting seat moves to the upper end of the stroke, the controller adjusts the electric control valve to the cut-off state. The controller detects the internal air pressure of the welded bellows based on the air pressure sensor to determine whether the welded bellows is damaged.

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