Fatigue life testing equipment and method for welded corrugated pipe

Abstract

The invention relates to the technical field of welding corrugated pipe testing equipment, and particularly discloses fatigue life testing equipment and method for a welding corrugated pipe. The testing equipment comprises a machine body, a connecting seat assembly, a controller, an air inlet pipeline, a limiting seat and a limiting ejector rod, the connecting base assembly comprises a lower connecting base and an upper connecting base which are used for being fixedly connected with connectors at the two ends of the welded corrugated pipe in a sealed mode and is provided with an air pressure sensor used for detecting the air pressure in the welded corrugated pipe. An electric control valve is arranged on the air inlet pipeline, an exhaust valve is installed on the upper connecting seat, a position sensor is installed on the limiting ejector rod, and a limiting sensor, an ejector pin and a feeding mechanism are installed on the limiting seat. The testing equipment is simple in structure, and the working life and the operation energy efficiency can be remarkably improved; the air tightness detection function is achieved, the welded corrugated pipe does not need to be disassembled during air tightness detection, and convenience, rapidness, time saving and high efficiency are achieved; the testing equipment is ingenious and reasonable in structure, stable in performance, easy to implement and low in manufacturing and operating cost.

Description

Technical Field

[0001] The present invention relates to the technical field of welding bellows testing equipment, and in particular to fatigue life testing equipment and method for welding bellows. Background Art

[0002] As elastic components that combine high-precision sealing and motion transmission, welded bellows play an irreplaceable role in high-end manufacturing fields such as aerospace, vacuum equipment, and precision instruments. Fatigue life is a key indicator of welded bellows' quality and performance, and fatigue testing equipment is required to complete these tests. Currently, fatigue testing equipment for welded bellows varies widely in type and design, but most utilize a mechanical reciprocating drive mechanism to drive the bellows' reciprocating and retracting motion. The complex structure of this mechanical reciprocating drive mechanism, coupled with the need for adjustable retraction and retraction, makes the testing equipment cumbersome and space-consuming. Furthermore, mechanical reciprocating drives experience significant transmission losses and mechanical wear during operation, resulting in a short operating life of the testing equipment, low energy efficiency, and high testing costs. Furthermore, during testing, the welded bellows must be tested for airtightness to determine if they are damaged. This typically requires the use of additional equipment, making assembly and disassembly of the bellows cumbersome and significantly reducing the overall efficiency of fatigue life testing. Summary of the Invention

[0003] In order to overcome the shortcomings of the existing technology, the present invention provides a fatigue life testing equipment for welded bellows, which uses high-pressure gas to drive the welding bellows to extend, and relies on the resilience of the welding bellows itself and the gravity of its related components to shrink, omitting the mechanical reciprocating transmission mechanism. The overall structure of the testing equipment is very simple, the performance is stable, the energy consumption is low, and it has an air tightness detection function.

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

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: A fatigue life testing device for a welding bellows comprises a body, a connecting seat assembly and a controller; the body is provided with a guide rod, an air intake pipe and a limit seat; the guide rod is fixed to the body and extends vertically; the connecting seat assembly comprises a lower connecting seat fixed to the body and an upper connecting seat slidably connected to the guide rod; an air pressure sensor is installed in the connecting seat assembly; one end of the air intake pipe is connected to the inside of the welding bellows, and the other end is connected to a high-pressure air source device and is provided with an electric control valve; an exhaust valve is installed on the upper connecting seat, and a valve stem is provided in the exhaust valve, and a valve plate is fixed on the valve stem; when the valve stem moves upward, the exhaust valve will reach the cut-off point When the valve stem is in the stopped state, it moves downward and the exhaust valve will reach the open state; a retractable limit push rod is fixed in the lower connecting seat, and a position sensor is installed on the limit push rod; when the upper connecting seat moves to the lower end of the stroke, the valve stem is limited by the limit push rod and the exhaust valve reaches the cut-off state; a limit sensor, a push pin and a feed mechanism are installed on the limit seat, and the push pin has an upper position and a lower position; when the push pin is in the lower position and the upper connecting seat is at the upper end of the stroke, the valve stem and the push pin abut against each other and the exhaust valve reaches the open state; when the push 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 push pin.

[0006] In a preferred embodiment, two guide rods are provided, and the upper ends of the two guide rods are fixedly connected via a connecting arm to form a portal structure.

[0007] In a preferred embodiment, a guide sleeve that matches the guide rod one by one is fixed on the upper connecting seat, and the guide sleeve is sleeved on the corresponding guide rod and the two are slidably matched.

[0008] 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 world through the side hole. A valve cover is fixed to 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 fitted. A limiting boss is provided on the valve stem, and the limiting boss is located above the guide tube.

[0009] In a preferred embodiment, the position sensor is a contact sensor, which is installed at the upper end of the limit push rod and is directly opposite to the lower end of the valve stem; during the downward movement of the upper connecting seat, the valve stem is thrust by the position sensor to make the exhaust valve reach the cut-off state.

[0010] In a preferred embodiment, a sliding sleeve that matches the guide rod one by one is fixed on the limit seat, the sliding sleeve is sleeved on the corresponding guide rod and the two are slidably matched, and a locking piece is installed on the sliding sleeve.

[0011] In a preferred embodiment, a vertically extending slide groove is provided on the limit seat, the push pin is located in the slide groove and slides in engagement, and a downwardly extending screw hole is provided at the upper end of the push pin; the feeding mechanism includes a driving motor whose working state is controlled by a controller, the driving motor is fixed on the limit seat and the output shaft is connected to a screw rod, and the screw rod is threadedly engaged with the screw hole.

[0012] In a preferred embodiment, the limit sensor is a contact sensor, the sensing end of which is located on the lower side of the limit seat. When the upper connecting seat reaches the upper end of the stroke, it can make direct or indirect contact with the upper connecting seat to prompt the limit sensor to feedback a signal to the controller.

[0013] 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 body; an air intake hole is opened in the lower connecting seat, one end of the air intake pipe is connected to the inside of the welded bellows through the air intake hole, and the other end of the air intake pipe is connected to an air intake joint; the air intake joint is fixed on the outer wall of the body.

[0014] In a preferred embodiment, the upper connecting seat is disc-shaped, and a plurality of counterweight rings are placed on the upper side.

[0015] In a preferred embodiment, the controller is mounted on the machine body, the guide rod is a tubular structure, 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, the other end of the wire extends through the inside of the guide rod into the machine body and is connected to the controller, and a spring-type telescopic section is provided at the end of the wire connected to the terminal block.

[0016] In a preferred embodiment, the controller is installed in the machine body, and a terminal block electrically connected to the drive mechanism and the limit sensor and a probe arm extending outward are fixed on the limit seat, and 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 connecting seat and the lower connecting seat, and the part of the wire located on the lower side of the probe arm is provided with a spring-type telescopic section.

[0017] A fatigue life testing method for a welded bellows is provided, wherein the fatigue life testing device is used to perform fatigue testing on the welded bellows, comprising the following steps: Step 1: Adjust the travel range of the upper connecting seat according to the expansion and contraction test requirements of the welded bellows; Adjust the position of the lower end and upper end of the stroke of the upper connecting seat 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 in the contracted state required by the test; 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 in the extended state required by the test; Step 2: Install and fix the welding bellows; Seal and fix the joints at both ends of the welded bellows to the lower connecting seat and the upper connecting seat respectively; Step 3: driving the welded bellows to perform reciprocating telescopic motion; The test equipment is started, and the controller adjusts the ejector pin to the upper working position. When the upper connecting seat moves to the lower end of the stroke, the controller adjusts the electric control valve to the open state. When the upper connecting seat moves to the upper end of the stroke, the controller adjusts the electric control valve to the closed state. This causes the welding bellows to perform reciprocating telescopic motion. Step 4: Conduct air tightness test on the welded bellows; The controller adjusts the ejector pin to the upper working position. When 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 welding bellows based on the air pressure sensor to determine whether the welding bellows is damaged.

[0018] Compared with the prior art, the fatigue life testing equipment for welded bellows in the present invention has the following beneficial technical effects: 1. This test equipment does not have complex mechanical reciprocating transmission mechanisms and reduction mechanisms, which not only simplifies the overall structure of the test equipment, but also significantly improves the working life and operating energy efficiency by avoiding a large amount of mechanical friction.

[0019] 2. This test equipment uses high-pressure gas to drive the welding bellows to reciprocating and telescopic motion, and the telescopic amount is adjustable. At the same time, based on the structure that realizes the above functions, the air tightness detection function is realized without significantly increasing the cost, making the function of this test equipment perfect and the overall cost reduced; more significantly, when performing air tightness testing, there is no need to disassemble the welding bellows and the testing operation does not need to be interrupted, which is convenient, fast, time-saving and efficient.

[0020] 3. The overall structure of this test equipment is ingenious and reasonable. It is powered by high-pressure gas in a single direction. The exhaust valve can automatically adjust the on-off state as the stroke changes without setting up a complex reversing mechanism. It has stable performance, is easy to implement, and has low manufacturing and operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0022] Figure 1 This is one of the overall structural schematic diagrams of the fatigue life testing equipment in the present invention.

[0023] Figure 2 This is the second schematic diagram of the overall structure of the fatigue life testing equipment in the present invention.

[0024] Figure 3 It is a schematic diagram of the matching structure of the upper connecting seat and the exhaust valve in the present invention.

[0025] Figure 4 It is a structural schematic diagram of the upper side of the limit seat in the present invention.

[0026] Figure 5 It is a structural schematic diagram of the lower side of the limit seat in the present invention.

[0027] Figure 6 It is a structural schematic diagram of the ejector pin and feed mechanism in the present invention.

[0028] Figure 7 This is a schematic diagram of the gas circuit and circuit connection status in the fatigue life testing equipment of the present invention.

[0029] Figure 8 This is a schematic diagram of the connection status of the fatigue life testing equipment and the welded bellows in the present invention.

[0030] Figure 9 This is a schematic diagram of the state when the upper connecting seat reaches the lower end of the stroke during the test.

[0031] Figure 10 Schematic diagram of the state where high-pressure gas drives the welding bellows to stretch during the test.

[0032] Figure 11 This is a schematic diagram of the state when the upper connecting seat reaches the upper end of the stroke during the test.

[0033] Figure 12 This is a schematic diagram of the exhaust valve status when the upper connecting seat reaches the upper end of the stroke during the test.

[0034] Figure 13 Schematic diagram of the shrinkage of the welded bellows during the test.

[0035] Figure 14 Schematic diagram of the exhaust valve status when the welded bellows shrinks during the test.

[0036] Figure 15 This is a schematic diagram of the state of the fatigue life testing equipment in the air tightness detection mode of the present invention.

[0037] Figure 16 Schematic diagram of the coordination between the ejector pin and the exhaust valve in the air tightness detection mode.

[0038] Figure 17 Schematic diagram of the structure in which the wire extends inside the guide rod.

[0039] Figure 18 This is a schematic diagram of the state where the wire is supported and guided by the probe arm.

[0040] In the figure: 1. body, 2. controller, 3. lower connecting seat, 4. air pressure sensor, 5. position sensor, 6. guide rod, 7. exhaust valve, 8. valve stem, 9. locking piece, 10. drive motor, 11. connecting arm, 12. limit seat, 13. limit sensor, 14. sliding sleeve, 15. upper connecting seat, 16. guide sleeve, 17. limit push rod, 18. air inlet, 19. air inlet connector, 20. valve plate, 21. counter, 22. push pin, 23. side hole, 24. guide tube, 25. valve cover, 26. limit 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 DESCRIPTION

[0041] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] See Figure 1 、 Figure 2 、 Figure 7 、 Figure 8As shown, the embodiment discloses a fatigue life test device for a welded bellows, which includes a body 1, a connecting seat assembly and a controller 2; a guide rod 6, an air intake pipe 32 and a limit seat 12 are installed on the body 1; the guide rod 6 is one or more, fixed on the body 1 and extending vertically upward; the connecting seat assembly includes a lower connecting seat 3 and an upper connecting seat 15, and the lower connecting seat 3 and the upper connecting seat 15 can be respectively sealed and fixedly connected to the joints 34 at both ends of the welded bellows, and the two ends of the welded bellows are blocked; 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 and can move up and down. As a result, the upper connecting seat 15 can move up and down with the expansion and contraction movement of the welding bellows. At the same time, the upper connecting seat 15 also serves to guide the expansion and contraction movement of the welding bellows, preventing the welding bellows from deflecting during expansion and contraction, thereby improving test accuracy. A pressure sensor 4 is installed in the connecting seat assembly. The pressure sensor 4 is used to detect the air pressure inside the welding bellows and feed the signal back to the controller 2. One end of the air inlet pipe 32 is connected to the interior of the welding bellows through the connecting seat assembly, and the other end is used to connect to the high-pressure air source equipment. The air inlet pipe 32 is installed with an electrically controlled valve 33 for adjusting the on-off state. Based on this configuration, high-pressure gas can be injected into the interior of the welding bellows to drive the welding bellows to expand. The operating state of the electrically controlled valve 33 is controlled by the controller 2, and can be a solenoid valve or an electric valve.

[0043] See Figure 1-Figure 3 As shown, an exhaust valve 7 is fixedly installed on the upper connecting seat 15, and a valve port is provided at the lower end of the exhaust valve 7 to communicate with the valve cavity, and the valve cavity is communicated with the interior of the welded bellows through the valve port. At the same time, the valve cavity is communicated with 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, and the upper and lower ends of the valve stem 8 extend to the upper and lower ends of the exhaust valve 7 respectively. The valve stem 8 and the exhaust valve 7 are slidably matched and can move up and down. A valve disc 20 is fixed on the valve stem 8, and the valve disc 20 is located at the lower side of the valve port; when the valve stem 8 moves upward, the valve disc 20 will be attached to the exhaust valve 7. It leans against the lower side of the valve port to block the valve port, thereby making the exhaust valve 7 reach the cut-off state, that is, the interior of the welded bellows cannot communicate with the outside world through the exhaust valve 7; when the valve stem 8 moves downward, the valve plate 20 separates from the valve port and the exhaust valve 7 reaches the open state, and as the valve stem 8 moves downward, the opening of the exhaust valve 7 gradually increases; since the valve plate 20 and the valve stem 8 always maintain a downward movement trend due to their own weight, the exhaust valve 7 can be regarded as a self-powered 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.

[0044] See Figure 1 、 Figure 2 、 Figure 7 、 Figure 9As shown, a limit rod 17 extending vertically upward is fixed in the lower connecting seat 3, and the limit rod 17 is located directly below the valve stem 8. A position sensor 5 is installed on the limit rod 17. The limit rod 17 is a telescopic structure, so that the height of its upper end and the position sensor 5 can be adjusted; in the process of the upper connecting seat 15 moving downward as the welding bellows shrinks, the valve stem 8 is limited by the limit rod 17 and cannot continue to move downward, and the exhaust valve 7 will gradually reach a 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 welding bellows shrinks to the minimum length; based on the above-mentioned matching 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 limit 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.

[0045] See Figure 1 、 Figure 2 、 Figure 4-Figure 7 As shown, the limit seat 12 is located above the upper connecting seat 15 and is height-adjustable, and a limit sensor 13, a push pin 22 and a feed mechanism are installed on the limit seat 12; the push pin 22 is slidably connected to the limit seat 12 and is located just above the valve stem 8, and the push pin 22 has two working states, an upper position and a lower position, and the push pin 22 is driven by the feed mechanism to switch the positions; the limit 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 the stroke as the welding bellows extends, the controller 2 adjusts the electric control valve 33 to the cut-off state, that is, stops filling the welding bellows with high-pressure gas, and thereafter the welding bellows will not be able to continue to extend, that is, the upper connecting seat 15 cannot continue to move upward after reaching the upper end of the 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 limit seat 12; as shown Figure 11 、 Figure 12 As shown, when the ejector pin 22 is in the lower position, the upper connecting seat 15 moves to the upper end of the stroke, and the upper end of the valve stem 8 hits the ejector pin 22 and cannot continue to move upward. When the upper connecting seat 15 moves to the upper end of the stroke, the exhaust valve 7 reaches the open state; Figure 15 、 Figure 16 As shown, when the ejector pin 22 is in the upper position, the fatigue life testing equipment enters the airtightness detection 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 ejector pin 22.

[0046] The test method and working principle of the fatigue life test equipment of this welded bellows are as follows: 1. According to the expansion and contraction test requirements of the welded bellows, adjust the travel range of the upper connecting seat 15.

[0047] Based on the above structure, it can be determined that the travel range of the upper connecting seat 15 determines the expansion and contraction amount of the welding bellows. Therefore, by adjusting the travel range of the upper connecting seat 15 accordingly, it can be ensured that the expansion and contraction amount of the welding bellows during the test meets the test requirements; specifically, Figure 9 As shown, by adjusting the height of the upper end of the limiting push 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 tested welded bellows is consistent with the minimum length in the contracted state required by the test; similarly, 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 tested welded bellows is consistent with the maximum length in the extended state required by the test.

[0048] 2. Install and fix the welded bellows.

[0049] like Figure 8 As shown, the welding bellows is placed vertically between the lower connecting seat 3 and the upper connecting seat 15, and the limiting push rod 17 is located inside the welding bellows; the joints 34 at both ends of the welding 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.

[0050] 3. Drive the welded bellows to perform reciprocating telescopic motion.

[0051] Connect the air inlet 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 ejector pin 22 to the upper working position based on the feed mechanism, and the ejector pin 22 maintains the upper working position during the test; the test equipment operates under the coordination 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 the stroke, the welding bellows contracts to the minimum length, and the exhaust valve 7 switches to the closed state. At this time, the controller 2 adjusts the electric control valve 33 to the open state, and high-pressure gas enters the welding bellows, driving the welding bellows to extend; in this process, due to the high pressure inside the welding bellows, the valve plate 20 can be pressed against the valve port, thereby maintaining 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 the stroke, the welding bellows extends to its maximum length, and the exhaust valve 7 switches to the open state. At this time, the controller 2 adjusts the electric control valve 33 to the cut-off state, that is, stops filling the welding bellows with high-pressure gas; thereafter, as shown in FIG. Figure 13 、 Figure 14As shown, the welding bellows will retract downward based on its own resilience and the gravity of components such as the upper connecting seat 15. During the retraction of the welding bellows, the valve plate 20 and the valve stem 8 will slide downward based on their own weight, so that the exhaust valve 7 is automatically reset to the maximum opening, that is, the fully open state, so that the gas inside the welding bellows can be discharged in time as it shrinks, so as to increase the shrinkage rate of the welding bellows; thus, the welding bellows is made to perform reciprocating telescopic motion in the above manner to achieve the purpose of fatigue life testing.

[0052] 4. Perform air tightness test on welded bellows.

[0053] like Figure 7 、 Figure 15 、 Figure 16 As shown, according to the test requirements, when the welding bellows is tested for air tightness, the controller 2 adjusts the push pin 22 to the upper working position based on the feed mechanism, and the test equipment enters the air tightness test mode; when the upper connecting seat 15 moves upward to the upper end of the stroke as the welding bellows stretches, the controller 2 adjusts the electric control valve 33 to the cut-off state. Since the push pin 22 is in the upper working position, it cannot contact the valve stem 8, so that the exhaust valve 7 still maintains the cut-off state. At this time, the interior of the welding bellows is in a closed high-pressure state. The controller 2 detects the internal air pressure of the welding bellows based on the air pressure sensor 4. If the air pressure is stable, it means that the welding bellows is not damaged. If the test needs to continue, the controller 2 adjusts the push pin 22 to the lower working position based on the feed mechanism. The push pin 22 pushes the valve stem 8 downward, so that the exhaust valve 7 is switched to the open state, thereby restoring normal operating state; if the air pressure gradually decreases, it means that the welding bellows is leaking and has been damaged, and the test should be terminated.

[0054] This test equipment uses high-pressure gas to drive the welding bellows to extend, and the welding bellows uses its own resilience and the gravity of other components to retract, thereby achieving reciprocating telescopic motion. There is no need to set up a complex mechanical reciprocating transmission mechanism and deceleration mechanism. This not only simplifies the overall structure of the test equipment, but also avoids a large amount of mechanical friction, thereby significantly improving the service life and operating energy efficiency.

[0055] This testing equipment uses high-pressure gas to drive the welded bellows to perform reciprocating telescopic motion, which can achieve the purpose of fatigue life testing and can easily and quickly adjust the telescopic amount; at the same time, based on the structure that realizes the above functions, the air tightness detection function is realized without increasing significant costs, making the function of this testing equipment perfect and the overall cost reduced; more significantly, when performing air tightness testing, there is no need to disassemble the welded bellows and the testing operation does not need to be interrupted, which is convenient, fast, time-saving and efficient.

[0056] The overall structure of this test equipment is ingenious and reasonable. It is powered by high-pressure gas in a single direction. The exhaust valve can automatically adjust the on-off state as the stroke changes without setting up a complex reversing mechanism. It is easy to implement, has low manufacturing and operating costs, and high stability.

[0057] Preferably, Figure 1 、 Figure 2 As shown, there are two guide rods 6, and the upper ends of the two guide rods 6 are fixedly connected via a connecting arm 11 to form a portal structure to improve the simplicity of the device and ensure that the guide rods 6 have good stability.

[0058] In the prior art, the joint 34 of the welded bellows product has a variety of structural designs, such as a flange or a threaded head; accordingly, the lower connecting seat 3 and the upper connecting seat 15 have a variety of structural designs, such as a flange seat or a threaded seat, to adapt to the joint 34 structure of the welded bellows; at the same time, sealing rings, sealing gaskets 27 and other sealing parts can be provided on the lower connecting seat 3 and the upper connecting seat 15 to ensure the connection sealing of the lower connecting seat 3, the upper connecting seat 15 and the welded bellows joint 34.

[0059] Specifically, such as Figure 1 、 Figure 2 As shown, a plurality of guide sleeves 16 are fixed on the upper connecting seat 15 , and the guide sleeves 16 match 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.

[0060] Specifically, such as Figure 1 、 Figure 3 As shown, a side hole 23 is provided on the side wall of the exhaust valve 7, and 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 to the upper end of the exhaust valve 7, and 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 are slidably matched. A limiting boss 26 is provided on the valve stem 8, and the limiting boss 26 is located above the guide tube 24 to limit the stroke of the valve stem 8 to prevent the valve stem 8 from moving downward and slipping out of the guide tube 24.

[0061] Preferably, the position sensor 5 is a contact sensor, which is installed at the upper end of the limiting push rod 17 and is directly opposite to the lower end of the valve stem 8; in the process of the upper connecting seat 15 moving downward, the valve stem 8 is provided with thrust by the position sensor 5, so that the exhaust valve 7 reaches the cut-off state. At the same time, the position sensor 5 feeds back a signal to the controller 2 after contacting the valve stem 8; because the upper connecting seat 15 has not reached the lower end of the 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 cut-off state; therefore, after the controller 2 receives the signal generated by the contact between the position sensor 5 and the valve stem 8, it should be delayed for a certain time, and then the electric control valve 33 is adjusted to the open state to ensure that the upper connecting seat 15 can reach the position of the lower end of the stroke, thereby improving the accuracy of the operating parameters of the test equipment, and also ensuring that the exhaust valve 7 can reach the cut-off state, thereby improving the stability of the test equipment operation.

[0062] Specifically, such as Figure 1 、 Figure 2 As shown, a sliding sleeve 14 that matches the guide rod 6 one by one is fixed on the limit seat 12. The sliding sleeve 14 is sleeved on the corresponding guide rod 6 and the two are slidably matched. A locking member 9 such as a bolt is installed on the sliding sleeve 14 to lock the sliding sleeve 14 and the guide rod 6.

[0063] Preferably, see Figure 5 、 Figure 6 As shown, a vertically extending slide groove 30 is provided on the limit seat 12, and the ejector pin 22 is located in the slide groove 30 and slides in engagement, and a downwardly extending screw hole 29 is provided at the upper end of the ejector pin 22; the feeding mechanism includes a driving motor 10, the driving motor 10 is mounted and fixed on the limit seat 12 and the output shaft is connected to a screw rod 31, the screw rod 31 extends into the screw hole 29 and the two are threadedly engaged; the driving motor 10 is controlled in its working state by the controller 2; thus, the driving motor 10 can drive the ejector pin 22 to move up and down, and the controller 2 can adjust the position of the ejector pin 22 based on the regulation of the driving motor 10; the driving motor 10 can adopt a micro stepping motor to improve the controllability of the position of the ejector pin 22.

[0064] Preferably, the limit sensor is a contact sensor, and the sensing end is located on the lower side of the limit seat 12. When the upper connecting seat 15 reaches the upper end of the stroke, it can make direct or indirect contact with the upper connecting seat 15 to prompt the limit sensor to feedback a signal to the controller 2.

[0065] Preferably, 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, the air intake pipe 32, and the electric control valve 33 are installed in the body 1; an air intake hole 18 is provided in the lower connecting seat 3, and one end of the air intake pipe 32 is connected to the inside of the welded bellows through the air intake hole 18, and the other end of the air intake pipe 32 is connected to the air intake connector 19; the air intake connector 19 is fixed to the outside of the body 1 to facilitate connection with the high-pressure air source equipment.

[0066] When the test equipment disclosed in the present invention performs a test, refer to Figure 13 As shown, during the downward movement of the upper connecting seat 15, the welding bellows contracts. The power in this process comes from the resilience of the welding bellows itself and the gravity of the upper connecting seat 15, the exhaust valve 7 and other components. This makes the speed of the upper connecting seat 15's downward movement unadjustable, and may even cause the upper connecting seat 15 to fail to reach the lower end of its travel. Based on the above situation, the solution of the present invention is: like Figure 9 As shown, the upper connecting seat 15 is disc-shaped, and a number of annular counterweight rings 35 are placed on the upper side; therefore, when the test equipment is working, the number of counterweight rings 35 can be adjusted according to the operation needs to adjust the weight on the upper side of the upper connecting seat 15, so as to regulate the speed of the downward movement of the upper connecting seat 15 to improve the test efficiency and avoid the situation where the upper connecting seat 15 cannot reach the lower end of the stroke.

[0067] In the test device disclosed in the present invention, the controller 2 can count the number of reciprocating movements of the connecting seat 15 based on the signals fed back by the position sensor 5, the limit sensor 13 and other components, that is, obtain the number of expansion and contraction of the welding bellows; at the same time, Figure 2 、 Figure 5 、 Figure 7 As shown, the accuracy of recording the number of expansion and contraction times of the welding bellows can be further improved by installing a counter 21 . The counter 21 can be installed on the limiting seat 12 or the limiting push rod 17 .

[0068] In the present invention, the drive mechanism, the limit sensor 13, and the controller 2 need to be electrically connected via a wire 36. To improve the structural simplicity of the test equipment and prevent the wire 36 from interfering with the movement of other components, the present invention provides two specific arrangements for the wire 36: 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, and a terminal block 28 is fixed on the limit seat 12. The terminal block 28 is electrically connected to the drive mechanism and the limit sensor 13. The terminal block 28 is connected to a wire 36, and the other end of the wire 36 extends into the body 1 through the inside of the guide rod 6 and is connected 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 be extended and retracted as the limit seat 12 is adjusted up and down; based on this design, the upper and lower extending parts of the wire 36 are hidden in the guide rod 6, so that the external structure of the test equipment is simpler, and at the same time, the wire 36 is prevented from interfering with the movement of the upper connecting seat 15 and the welding bellows.

[0069] The second is: Figure 7 、 Figure 18 As shown, the controller 2 is installed in the body 1, and a terminal block 28 and a probe arm 37 extending outward are fixed on the limit seat 12. The terminal block 28 is electrically connected to the drive mechanism and the limit 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 welding bellows; the part of the wire 36 located on the lower side of the probe arm 37 is provided with a spring-type telescopic section, so that the wire 36 can be extended and retracted as the upper and lower positions of the limit seat 12 are adjusted.

Claims

1. A fatigue life testing device for a welded bellows, comprising a body, a connector assembly, and a controller; characterized in that: The body is provided with a guide rod, an air intake pipe and a limit 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; an air pressure sensor is installed in the connecting seat assembly; one end of the air intake pipe is connected to the inside of the welded bellows, and the other end is connected to the high-pressure air source equipment, and is provided with an electric control valve; an exhaust valve is installed on the upper connecting seat, and a valve stem is provided in the exhaust valve, and a valve plate is fixed on the valve stem; when the valve stem moves upward, the exhaust valve will reach a closed state, and when the valve stem moves downward, the exhaust valve will reach an open state Open state; a retractable limit push rod is fixed in the lower connecting seat, and a position sensor is installed on the limit push rod; when the upper connecting seat moves to the lower end of the stroke, the valve stem is limited by the limit push rod and the exhaust valve reaches the cut-off state; a limit sensor, a push pin and a feed mechanism are installed on the limit seat, and the push pin has an upper position and a lower position; when the push pin is in the lower position and the upper connecting seat is at the upper end of the stroke, the valve stem and the push pin hit each other and the exhaust valve reaches the open state; when the push 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 push pin.

2. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: There are two guide rods, and the upper ends of the two guide rods are fixedly connected via a connecting arm to form a portal structure.

3. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: A guide sleeve that matches the guide rod one by one is fixed on the upper connecting seat. The guide sleeve is sleeved on the corresponding guide rod and the two are slidably matched.

4. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: A side hole is provided on the side wall of the exhaust valve, and the valve cavity of the exhaust valve is connected with the outside world through the side hole. A valve cover is fixed to 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 fitted. 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, which is installed at the upper end of the limit push rod and is directly opposite to the lower end of the valve stem.

6. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: A sliding sleeve that matches the guide rod one by one is fixed on the limit seat. The sliding sleeve is sleeved on the corresponding guide rod and the two are slidably matched. A locking piece is installed on the sliding sleeve.

7. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: A vertically extending slide groove is provided on the limit seat, the push pin is located in the slide groove and slides in engagement, and a downwardly extending screw hole is provided at the upper end of the push pin; the feed mechanism includes a drive motor whose working state is controlled by a controller, the drive motor is fixed on the limit 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, and the sensing end is located at the lower side of the limit seat. When the upper connecting seat reaches the upper end of the stroke, it can make direct or indirect contact with the upper connecting seat to prompt the limit sensor to feedback a signal to the controller.

9. The fatigue life testing equipment for welded bellows according to claim 1, characterized in that: The upper connecting seat is in the shape of a disk, and a plurality of counterweight rings are placed on the upper side.

10. A fatigue life testing method for a welded bellows, characterized by: A fatigue test is performed using the fatigue life testing equipment for a welded bellows according to any one of claims 1 to 9, comprising the following steps: Step 1: Adjust the travel range of the upper connecting seat according to the expansion and contraction test requirements of the welded bellows; Adjust the position of the lower end and upper end of the stroke of the upper connecting seat 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 in the contracted state required by the test; 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 in the extended state required by the test; Step 2: Install and fix the welding bellows; Seal and fix the joints at both ends of the welded bellows to the lower connecting seat and the upper connecting seat respectively; Step 3: driving the welded bellows to perform reciprocating telescopic motion; The test equipment is started, and the controller adjusts the ejector pin to the upper working position. When the upper connecting seat moves to the lower end of the stroke, the controller adjusts the electric control valve to the open state. When the upper connecting seat moves to the upper end of the stroke, the controller adjusts the electric control valve to the closed state. This causes the welding bellows to perform reciprocating telescopic motion. Step 4: Conduct air tightness test on the welded bellows; The controller adjusts the ejector pin to the upper working position. When 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 welding bellows based on the air pressure sensor to determine whether the welding bellows is damaged.

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