Fatigue test device and method for pressurized metal bellows

Abstract

The application provides a fatigue test device and method for a metal bellows under pressure, and relates to the technical field of fatigue testing. The fatigue test device for the metal bellows under pressure comprises: a fixing platform used for fixing a lower flange of the bellows; an actuating part used for connecting an upper flange of the bellows, wherein the actuating part is driven to do vertical reciprocating motion, and the bellows is arranged vertically; a pressure loading part in communication with an inner cavity of the bellows and used for injecting pressure medium into the bellows; and a pressure sensor used for monitoring a pressure value in the inner cavity of the bellows.

Description

Technical Field

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

[0002] Engine piping systems are subject to temperature changes, vibrations, and torsion during operation. Therefore, flexible components are needed within the system to absorb pipe deformation and prevent damage. Depending on factors such as operating temperature, pressure, and medium, the flexible components can be made of metallic or non-metallic materials. In marine diesel engine turbocharger systems, due to the high intake and exhaust temperatures, metallic bellows are often used to compensate for system deformation. Metallic bellows are subjected to repeated tensile and compressive deformation during operation; therefore, their fatigue life is a crucial evaluation indicator in bellows design.

[0003] In the fatigue test of metal bellows, one end of the bellows is fixed to the test platform, and the other end is connected to the testing machine. The testing machine reciprocates up and down, causing one end of the bellows to reciprocate up and down, thus achieving tensile and compressive deformation of the bellows. The fatigue test of the bellows is achieved through repeated tensile and compressive deformation of the bellows section. However, currently, the bellows in the fatigue test can only be subjected to normal pressure conditions, which differs from the actual service conditions of the bellows. Summary of the Invention

[0004] The purpose of this invention is at least to provide a fatigue testing device and method for pressurized metal bellows.

[0005] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0006] One embodiment of the present invention provides a fatigue testing device for a pressurized metal bellows. The device includes: a fixed platform for fixing the lower flange of the bellows; an actuating component for connecting to the upper flange of the bellows, the actuating component being driven to perform vertical reciprocating motion, wherein the bellows is arranged vertically; a pressure loading component communicating with the inner cavity of the bellows for injecting a pressure medium into the bellows; and a pressure sensor for monitoring the pressure value inside the bellows.

[0007] In some embodiments, the bellows includes a first bellows and a second bellows. The two ends of the first bellows are respectively sealed to the lower flange and the first flange. The two ends of the second bellows are respectively sealed to the first flange and the second flange. The first bellows and the second bellows are connected through the first flange. The lower flange is connected to the second flange, and the upper flange is connected to the first flange. The actuating component can drive the first flange to perform vertical reciprocating motion.

[0008] In some embodiments, the upper flange is connected to the first flange by a vertically arranged first stud, and the lower flange is connected to the second flange by a vertically arranged second stud.

[0009] In some embodiments, the pressure loading component includes a hydraulic pump, and a connection interface is provided on the second flange. The connection interface communicates with the inner cavity of the bellows, and the hydraulic pump is connected to the connection interface to pump pressure medium into the bellows.

[0010] In some embodiments, a venting switch is provided on the second flange, which is connected to the inner cavity of the bellows. The venting switch is used to release excess gas in the bellows when a pressure medium is pumped in.

[0011] In some embodiments, a through hole is provided on the first flange, and the first bellows and the second bellows are connected through the through hole provided on the first flange. The diameter of the through hole is not less than the diameter of the first bellows or the second bellows.

[0012] In some embodiments, sealing gaskets or sealant are placed between the two ends of the bellows and the flange to achieve a sealed connection between the bellows and the flange.

[0013] One embodiment of the present invention provides a fatigue test method for a pressurized metal bellows, implemented based on the pressurized metal bellows fatigue test device described in the above embodiment. The test method includes: a pressure loading component injecting a pressure medium into the inner cavity of the bellows and maintaining a set pressure; a fatigue testing machine driving an actuating component to reciprocate, setting a number of cycle tests, and confirming the deformation of the bellows after reaching the number of cycle tests.

[0014] In some embodiments, the test method includes: opening the vent switch, starting the hydraulic pump to pump the pressure medium into the bellows, closing the vent switch when the pressure medium overflows from the vent switch, continuing to pump in the hydraulic pump until the pressure monitored by the pressure sensor reaches the set pressure, and then turning off the hydraulic pump.

[0015] In some embodiments, after the hydraulic pump is turned off, the fatigue testing machine drives the actuating parts to reciprocate. Based on the pressure data monitored by the pressure sensor, the sealing performance of the bellows is determined. If the pressure data monitored by the pressure sensor drops below the allowable value ΔP, it is determined that the bellows is leaking, and the fatigue testing machine stops operating. Attached Figure Description

[0016] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related properties or features may have the same or similar reference numerals. Wherein: Figure 1 This is a structural schematic diagram of a pressure-bearing metal bellows fatigue testing device according to some embodiments.

[0017] Figure 2 This is a partial structural schematic diagram of a pressure-bearing metal bellows fatigue testing device according to some embodiments.

[0018] Figure 3 This is a partial dimensional schematic diagram of a pressure-bearing metal bellows fatigue testing device according to some embodiments.

[0019] Explanation of reference numerals in the attached figures: 110-Lower flange; 120 - First corrugated pipe; 130 - First flange; 131 - Through hole; 140 - Second corrugated pipe; 150 - Second flange; 151 - Connection Interface; 152 - Vent port; 153 - Pressure Interface; 160 - Upper flange; 170-Stud. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0021] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other words can achieve the same purpose, they may be replaced by other expressions.

[0022] It is understood that the technical terms that may be used in the description of this specification, such as “center,” “longitudinal,” “lateral,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the implementation method and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the invention.

[0023] It should be noted that the use of terms such as "first" and "second" to define features in this document is merely for the purpose of distinguishing the corresponding features. Unless otherwise stated, these terms have no special meaning and should not be construed as limiting the scope of protection of this invention. As shown in this specification and claims, the terms "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural, unless the context clearly indicates otherwise. Generally, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, and these steps and elements do not constitute an exclusive list; the method or apparatus may also include other steps or elements.

[0024] In the description of this specification, it should also be noted that, unless otherwise expressly specified or limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, an integral connection, or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium, or a connection within two components, etc. Those skilled in the art can understand the specific meaning of the above terms in this specification according to the specific circumstances.

[0025] This specification describes an invention-based fatigue testing device for pressurized metal bellows, simulating the fatigue process of a bellows undergoing reciprocating tensile-compressive deformation while under internal pressure (pressurized) in actual working conditions such as the piping system of a marine diesel engine turbocharger. The pressurized metal bellows fatigue testing device integrates a pressure loading component, applying and maintaining a controllable static or quasi-static pressure on the bellows cavity based on the reciprocating motion driven by a traditional fatigue testing machine, thereby more realistically reproducing the actual working stress state of the bellows.

[0026] like Figure 1 As shown, the fatigue testing device for pressurized metal bellows includes a fixed platform, actuating components, pressure loading components, and pressure sensors.

[0027] The fixed platform is used to secure the lower flange 110 of the bellows. The fixed platform serves as the reference for the entire setup and is securely mounted on the ground or the fatigue testing machine base.

[0028] The actuating component is used to connect the upper flange 160 of the bellows. The actuating component and the fixed platform are vertically opposite each other and are driven by the actuating component of the testing machine. During the test, the fatigue testing machine drives the actuating component to perform a vertical reciprocating motion. The actuating component is a component of the fatigue testing machine, thereby causing the upper flange 160 of the bellows to move synchronously, achieving periodic axial tension and compression of the bellows. The vertical arrangement of the bellows ensures that the reciprocating motion direction of the actuating component is consistent with the bellows axis, making the bellows deformation mainly axial tension and compression, avoiding unexpected stresses such as bending or shearing caused by inclined installation, and meeting the loading requirements of standard fatigue tests.

[0029] The pressure loading component is connected to the inner cavity of the bellows and is used to inject a pressure medium (such as hydraulic oil, water or special test liquid) into the bellows and maintain a preset constant pressure value during fatigue testing.

[0030] A pressure sensor is used to monitor the pressure inside the bellows. The control system uses the pressure data monitored by the pressure sensor to implement closed-loop control of the actuating parts of the testing machine.

[0031] In some embodiments, the bellows includes a first bellows 120 and a second bellows 140. The lower end of the first bellows 120 is sealed to a lower flange 110, and the upper end of the first bellows 120 is sealed to a first flange 130. The lower end of the second bellows 140 is sealed to the first flange 130, and the upper end of the second bellows 140 is sealed to a second flange 150. The first bellows 120 and the second bellows 140 are connected in series through the first flange 130. The lower flange 110 is connected to the second flange 150, and the upper flange 160 is connected to the first flange 130. In some embodiments, the upper flange 160 is connected to the first flange 130 by a vertically arranged first stud 170, and the lower flange 110 is connected to the second flange 150 by a vertically arranged second stud 170. The actuating component can drive the first flange 130 to perform vertical reciprocating motion, and the first bellows 120 and the second bellows 140 will undergo deformation in the same phase but opposite direction (when one is stretched, the other is compressed).

[0032] In some embodiments, a through hole 131 is provided on the first flange 130, and the first bellows 120 and the second bellows 140 are connected through the through hole 131 provided on the first flange 130. The diameter of the through hole 131 is not less than the diameter of the first bellows 120 or the second bellows 140, so that the pressure medium inside the bellows flows smoothly through the first flange 130 without generating additional throttling losses or local pressure changes, so that the pressure inside the first bellows 120 and the second bellows 140 remains consistent, which is crucial for obtaining accurate test data.

[0033] The embodiments in this specification connect the first bellows 120 and the second bellows 140 in series, allowing the two bellows to be tested simultaneously in one test. This decomposes a long-stroke deformation onto the two bellows, improving the testing efficiency of the test equipment.

[0034] In some embodiments, a pressure port 153 is provided on the second flange 150, and the pressure port 153 is connected to the inner cavity of the bellows (including the first bellows 120 and the second bellows 140) through the second flange 150. A pressure sensor is connected to the pressure port 153 to monitor the pressure value inside the bellows.

[0035] In some embodiments, the pressure loading component includes a hydraulic pump, and a connection interface 151 is provided on the second flange 150. The connection interface 151 communicates with the inner cavity of a bellows (including a first bellows 120 and a second bellows 140) through the second flange 150. The outlet of the hydraulic pump is connected to the connection interface 151, thereby enabling the pumping of pressure medium into the bellows.

[0036] In some embodiments, for the sake of accurate pressure control, a venting port 152 is provided on the second flange 150. A venting switch (e.g., an exhaust valve or needle valve) is connected to the venting port 152. The venting switch communicates with the inner cavity of the bellows through the venting port 152. During the process of the hydraulic pump pumping in the pressure medium, opening the venting switch can release the gas remaining in the bellows and pipeline. When it is observed that the pressure medium continuously overflows from the venting switch without bubbles, the venting switch is then closed, thereby ensuring that the inner cavity of the bellows is filled with incompressible liquid and eliminating the interference of gas compression on pressure stability.

[0037] In some embodiments, since the test involves a pressure medium, a reliable seal must be maintained between the joint surfaces of the bellows and each flange (lower flange 110, first flange 130, second flange 150, and upper flange 160). Sealing gaskets or sealant are placed between the bellows and the flanges to achieve a sealed connection between the bellows and the flanges. Specifically, a sealing gasket or sealant is placed between the lower end of the first bellows 120 and the lower flange 110, and similarly between the upper end of the first bellows 120 and the first flange 130, the lower end of the second bellows 140 and the first flange 130, and the upper end of the second bellows 140 and the second flange 150, and the connecting studs 170 are tightened to form an effective sealing band.

[0038] This specification also describes a test method for conducting fatigue tests using the aforementioned apparatus. The test method includes: injecting a pressure medium into the inner cavity of the bellows using a pressure loading component and maintaining a set pressure; driving the actuating component of the fatigue testing machine to reciprocate, setting a set number of test cycles, and confirming the deformation of the bellows after reaching the set number of test cycles.

[0039] Setting the number of cyclic tests includes: running the test up to the set number of cyclic tests, then stopping the machine to check the deformation, cracks, and other deformation of the bellows to determine whether it passes the test.

[0040] In some embodiments, before the pressure loading component, i.e., the hydraulic pump, injects the pressure medium into the inner cavity of the bellows, the venting switch is opened, the hydraulic pump is started to pump the pressure medium into the bellows until the pressure medium overflows from the venting switch (when it overflows continuously and there are no bubbles, it indicates that the gas in the cavity has been exhausted), the venting switch is closed, the hydraulic pump continues to pump in, the pressure in the cavity begins to rise, until the pressure monitored by the pressure sensor reaches the set pressure, and then the hydraulic pump is turned off.

[0041] Bellows are at risk of breakage during fatigue testing. Current bellows fatigue testing methods primarily involve multiple disassemblies and inspections during the fatigue test to verify cracking, making the process complex and prone to errors in fatigue test counts. Therefore, in some embodiments, after pressure loading and shutting down the hydraulic pump, the fatigue testing machine drives the actuators to reciprocate, and the control system continuously monitors the pressure sensor data. Based on the pressure data monitored by the pressure sensor, the bellows' sealing performance is determined. If the pressure data detected by the pressure sensor drops below the allowable value ΔP, a leak is detected in the bellows, and the fatigue testing machine stops operating, ensuring the accuracy of fatigue test counts and the safety of the test. This embodiment, by adding a pressure sensor, eliminates the need for repeated disassembly of the bellows for sealing tests during fatigue testing, enabling real-time diagnosis of the bellows' own damage status, saving time and costs.

[0042] In some embodiments, the maximum axial compensation L of the bellows can control the fatigue testing machine to drive the actuating components to conduct fatigue tests on the bellows under full compression (compression amount L), full tension (tension amount L), or compression-tension (compression 1 / 2L, tension 1 / 2L). Specifically, this includes the following steps: a. Determine the clamping dimensions of each flange based on the tension and compression conditions of the actual fatigue test.

[0043] When conducting fatigue tests under full compression, X = A - 1 / 2L, where X: the distance between the flanges at both ends of the bellows in the initial installed state, and A: the distance between the flanges at both ends of the bellows in the free state. Y = 2 × A + BL, where Y: the distance between the lower flange 110 and the second flange 150 in the initial installed state, and B: the thickness of the first flange 130.

[0044] When conducting fatigue tests under full tension, X = A + 1 / 2L, Y = 2 × A + B + L.

[0045] When fatigue tests are conducted under tension and compression, X=A, Y=2×A+B.

[0046] Tighten the studs 170 to secure the lower flange 110, the first flange 130, and the second flange 150 according to the above spacing requirements, and at the same time fix the upper flange 160 to the fatigue test actuating component.

[0047] b. Install the pressure sensor onto the pressure port on the second flange 150, open the vent switch, start the hydraulic pump to pump the pressure medium into the bellows cavity until pressure medium flows out at the vent switch, close the vent switch, and the hydraulic pump continues to pressurize until the pressure reaches the set pressure P, then turn off the hydraulic pump.

[0048] c. Start the fatigue testing machine. The fatigue testing machine stroke is: downward 1 / 2L → upward L → downward 1 / 2L. One complete stroke counts as 1 fatigue test.

[0049] d. If the pressure drop of the pressure sensor exceeds the allowable value ΔP, a leak is detected, and the fatigue testing machine will automatically stop operating; otherwise, it will continue to run until the pressure drop exceeds 2... N times, where N: the design fatigue safety life of the bellows.

[0050] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification, especially for those skilled in the art. Furthermore, unless expressly stated in the claims, the order of elements and sequences, the use of numbers and letters, or other names in this specification are not intended to limit the order of the processes and methods described herein. Although various examples of currently considered useful embodiments of the invention have been discussed in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.

Claims

1. A fatigue testing device for pressurized metal bellows, characterized in that, The pressurized metal bellows fatigue testing device includes: A fixed platform is used to secure the lower flange of the bellows. An actuating component is used to connect the upper flange of the bellows. The actuating component is driven to perform a vertical reciprocating motion, wherein the bellows is arranged vertically. The pressure loading component is connected to the inner cavity of the bellows and is used to inject pressure medium into the bellows; A pressure sensor is used to monitor the pressure value inside the bellows.

2. The fatigue testing device for pressurized metal bellows according to claim 1, characterized in that, The bellows includes a first bellows and a second bellows. The two ends of the first bellows are sealed to the lower flange and the first flange, respectively. The two ends of the second bellows are sealed to the first flange and the second flange, respectively. The first bellows and the second bellows are connected through the first flange. The lower flange is connected to the second flange, and the upper flange is connected to the first flange. The actuating component can drive the first flange to make vertical reciprocating motion.

3. The fatigue testing device for pressurized metal bellows according to claim 2, characterized in that, The upper flange is connected to the first flange by a vertically arranged first stud, and the lower flange is connected to the second flange by a vertically arranged second stud.

4. The fatigue testing apparatus for pressurized metal bellows according to claim 2, characterized in that, The pressure loading component includes a hydraulic pump, and a connection interface is provided on the second flange. The connection interface communicates with the inner cavity of the bellows, and the hydraulic pump is connected to the connection interface to pump pressure medium into the bellows.

5. The fatigue testing apparatus for pressurized metal bellows according to claim 4, characterized in that, A vent switch is installed on the second flange. The vent switch is connected to the inner cavity of the bellows and is used to release excess gas in the bellows when the pressure medium is pumped in.

6. The fatigue testing apparatus for pressurized metal bellows according to claim 2, characterized in that, A through hole is provided on the first flange, and the first bellows and the second bellows are connected through the through hole provided on the first flange. The diameter of the through hole is not less than the diameter of the first bellows or the second bellows.

7. The fatigue testing apparatus for pressurized metal bellows according to claim 1, characterized in that, Sealing gaskets or sealant are placed between the two ends of the bellows and the flanges to achieve a sealed connection between the bellows and the flanges.

8. A fatigue test method for pressurized metal bellows, characterized in that, The test method is carried out using the pressure-bearing metal bellows fatigue testing apparatus according to any one of claims 1 to 7, and includes: The pressure loading component injects pressure medium into the inner cavity of the bellows and maintains the set pressure. The fatigue testing machine drives the moving parts to reciprocate, sets the number of cyclic tests, and confirms the deformation of the bellows after the number of cyclic tests is reached.

9. The fatigue test method for pressurized metal bellows according to claim 8, characterized in that, Based on the fatigue testing apparatus for pressurized metal bellows described in claim 5, the testing method includes: Open the vent switch and start the hydraulic pump to pump the pressure medium into the bellows. Once the pressure medium overflows from the vent switch, close the vent switch. The hydraulic pump will continue pumping until the pressure detected by the pressure sensor reaches the set pressure, at which point the hydraulic pump will be turned off.

10. The fatigue test method for pressurized metal bellows according to claim 9, characterized in that, After the hydraulic pump is turned off, the fatigue testing machine drives the actuating parts to reciprocate. Based on the pressure data monitored by the pressure sensor, the sealing performance of the bellows is determined. If the pressure data monitored by the pressure sensor drops below the allowable value ΔP, it is determined that the bellows is leaking, and the fatigue testing machine stops running.

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