Exhaust manifold mounting bolt clamping force variation evaluation method, device, and apparatus

Abstract

This invention discloses a method, apparatus, and equipment for evaluating the clamping force variation of exhaust manifold mounting bolts, relating to the field of fastener testing technology. The method includes measuring the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures, and the strain elongation of the bolt shank at operating temperature; combining the axial force-strain relationship curves to obtain the axial clamping force of the mounting bolt in the bolted connection at room temperature; measuring the strain elongation of the bolt shank in the bolted connection at operating temperature to obtain the residual strain elongation; and based on the residual strain elongation and the axial force-strain relationship curves, obtaining the residual axial clamping force and comparing it with the axial clamping force of the mounting bolt in the bolted connection at room temperature to evaluate the clamping force variation. This application can accurately reflect the clamping force attenuation of exhaust manifold mounting bolts under actual working conditions, improving the reliability and accuracy of measurement results.

Description

Technical Field

[0001] This application relates to the field of fastener testing technology, specifically to a method, apparatus, and equipment for evaluating the change in clamping force of exhaust manifold mounting bolts. Background Technology

[0002] With the development of internal combustion engine technology, the demand for high-temperature resistant and high-strength fasteners is increasing. Especially in high-temperature environments such as aircraft engines, automobiles, and marine internal combustion engine exhaust systems, the clamping force retention capability of bolts directly affects the safety and reliability of the entire system.

[0003] In high-temperature environments, bolt preload changes significantly due to strength degradation, thermal expansion deformation, and creep of both the bolt material and the clamped material. For exhaust manifold mounting bolts in internal combustion engines operating at high temperatures, traditional testing methods, such as strain gauge methods, ultrasonic methods, and pressure sensor methods, typically only measure bolt preload at room temperature and cannot accurately reflect changes in bolt tightening performance at actual operating temperatures. Therefore, accurately measuring the clamping force and its attenuation at high temperatures to understand the changes in preload of bolts made of different materials and their clamped components has become a pressing issue. Summary of the Invention

[0004] This application provides a method, apparatus, and equipment for evaluating the change in clamping force of exhaust manifold mounting bolts, which can accurately reflect the attenuation of clamping force of exhaust manifold mounting bolts under actual working conditions, thereby improving the reliability and accuracy of measurement results.

[0005] In a first aspect, embodiments of this application provide a method for evaluating the change in clamping force of exhaust manifold mounting bolts, the method comprising: The axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures were measured, as well as the strain elongation of the mounting bolt shank at the operating temperature. Tighten the mounting bolts and the clamped parts to form a bolted connection body, and combine the axial force-strain relationship curve to obtain the axial clamping force of the mounting bolts in the bolted connection body under room temperature conditions; The temperature of the bolted connection body is controlled to measure the strain elongation of the bolt shank in the bolted connection body at the working temperature. The remaining strain elongation is obtained by combining the strain elongation of the bolt shank in the bolted connection body at the working temperature. Based on the remaining strain elongation and the axial force-strain relationship curve, the remaining axial clamping force is obtained and compared with the axial clamping force of the bolts installed in the bolted connection under room temperature conditions, so as to realize the evaluation of the clamping force change.

[0006] In conjunction with the first aspect, in one embodiment, the measurement of the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures specifically includes: A high-temperature tensile testing machine was used to perform axial force and rod strain calibration tests on the mounting bolts of the exhaust manifold, and the thread engagement length of the mounting bolts on the test fixture was kept consistent with that in the actual working environment. A high-temperature extensometer is installed on the part of the mounting bolt shank that is exposed in the test fixture. After the temperature is raised to the target temperature, an axial tensile load is applied to the mounting bolt, and the axial force and the strain value of the mounting bolt shank are recorded during the tensile process. Linear fitting was used to obtain the axial force-strain relationship curve of the mounting bolt at the current target temperature, thereby obtaining the axial force-strain relationship curve of the mounting bolt at different temperatures.

[0007] In conjunction with the first aspect, in one embodiment, the measurement obtains the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures, and the strain elongation of the mounting bolt shank at the operating temperature. Specifically, the measurement of the strain elongation of the mounting bolt shank at the operating temperature includes: Place the mounting bolts into the high-temperature furnace and install a high-temperature extensometer on the shank of the mounting bolts; The temperature is gradually increased to the working temperature of the mounting bolt and maintained. The strain elongation of the mounting bolt shank is measured by a high-temperature extensometer to obtain the strain elongation of the mounting bolt shank at the working temperature.

[0008] In conjunction with the first aspect, in one embodiment, the tightened mounting bolts and the clamped components form a bolted connection body, and by combining the axial force-strain relationship curve, the axial clamping force of the mounting bolts in the bolted connection body under room temperature conditions is obtained, specifically including: Under room temperature conditions, tighten the mounting bolts and the clamped parts of the mounting bolts according to the standard torque or rotation method to obtain the bolted connection body; The strain of the bolt shank in the bolted connection is measured and substituted into the axial force-strain relationship curve under room temperature conditions. The resulting axial force is the axial clamping force of the bolt in the bolted connection under room temperature conditions.

[0009] In conjunction with the first aspect, in one embodiment, the method of controlling the temperature rise of the bolted connection body to measure the strain elongation of the bolt shank portion of the bolted connection body at the operating temperature specifically includes: The bolted connection body is placed in a high-temperature furnace and gradually heated to the working temperature and maintained. The strain of the bolt shank in the bolted connection body is measured to obtain the strain elongation of the bolt shank in the bolted connection body at the working temperature.

[0010] In conjunction with the first aspect, in one embodiment, obtaining the remaining strain elongation by combining the strain elongation of the mounting bolt shank at the operating temperature specifically includes: The remaining strain elongation at the operating temperature is calculated by subtracting the strain elongation of the bolt shank in the bolted connection from the strain elongation of the bolt shank at the operating temperature.

[0011] In conjunction with the first aspect, in one embodiment, the remaining axial clamping force is obtained based on the remaining strain elongation and the axial force-strain relationship curve, and compared with the axial clamping force of the bolts installed in the bolted connection at room temperature to evaluate the change in clamping force, specifically including: Substituting the remaining strain elongation as the strain variable into the axial force-strain relationship curve at the operating temperature, the resulting axial force is the remaining axial clamping force at the operating temperature. Based on the remaining axial clamping force at operating temperature and the axial clamping force of the bolts installed in the bolted connection at room temperature, the attenuation rate of the axial clamping force at operating temperature is calculated to evaluate the change in clamping force.

[0012] In conjunction with the first aspect, in one implementation method, the calculation of the axial clamping force attenuation rate at operating temperature is specifically as follows: a = 1 - F(T1) / F0 Where a represents the attenuation rate of axial clamping force at operating temperature, F(T1) represents the remaining axial clamping force at operating temperature, and F0 represents the axial clamping force of the bolts installed in the bolted connection at room temperature.

[0013] Secondly, embodiments of this application provide an exhaust manifold mounting bolt clamping force variation evaluation device, the exhaust manifold mounting bolt clamping force variation evaluation device comprising: The measurement module is used to measure the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures, as well as the strain elongation of the mounting bolt shank at the operating temperature. The module is used to tighten the mounting bolts and the clamped parts to form a bolted connection, and by combining the axial force-strain relationship curve, the axial clamping force of the mounting bolts in the bolted connection under room temperature conditions is obtained. The execution module is used to control the temperature rise of the bolted connection body to measure the strain elongation of the bolt shank in the bolted connection body at the working temperature, and to obtain the remaining strain elongation by combining the strain elongation of the bolt shank at the working temperature. The evaluation module is used to obtain the remaining axial clamping force based on the remaining strain elongation and the axial force-strain relationship curve, and compare it with the axial clamping force of the bolts installed in the bolted connection under room temperature conditions, so as to evaluate the change in clamping force.

[0014] Thirdly, embodiments of this application provide an exhaust manifold mounting bolt clamping force variation evaluation device, the exhaust manifold mounting bolt clamping force variation evaluation device includes a processor, a memory, and an exhaust manifold mounting bolt clamping force variation evaluation program stored in the memory and executable by the processor, wherein when the exhaust manifold mounting bolt clamping force variation evaluation program is executed by the processor, the steps of the exhaust manifold mounting bolt clamping force variation evaluation method described above are implemented.

[0015] The beneficial effects of the technical solutions provided in this application include: It can more accurately reflect the attenuation of clamping force of exhaust manifold mounting bolts under actual working conditions, improving the reliability and accuracy of measurement results. By testing and analyzing bolts of different materials and structural forms, it can provide engineers with valuable data support, helping them to better select appropriate materials and design parameters, thereby improving the overall performance of the product and ensuring the safe operation of the equipment. At the same time, accurately grasping the variation law of bolt clamping force helps prevent safety accidents caused by insufficient clamping force and ensures the long-term stable operation of related mechanical equipment. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the evaluation method for the clamping force variation of exhaust manifold mounting bolts in this application. Figure 2 A schematic diagram of the axial force and rod strain calibration test; Figure 3 A schematic diagram showing the measurement of strain elongation of the bolted rod at operating temperature. Figure 4 This is a schematic diagram of a bolted connection structure. Figure 5 This is a schematic diagram of the axial force-deformation relationship curve under a high temperature of 750℃. Figure 6 This is a schematic diagram of the expansion and deformation curve at 750℃. Figure 7 This is a schematic diagram of the deformation curve at 750℃. Figure 8 This is a schematic diagram of the functional modules of the exhaust manifold mounting bolt clamping force variation evaluation device of this application; Figure 9 This is a schematic diagram of the hardware structure of the equipment for evaluating the change in clamping force of exhaust manifold mounting bolts in this application. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0019] In a first aspect, embodiments of this application provide a method for evaluating the change in clamping force of exhaust manifold mounting bolts, which is used to measure the attenuation of clamping force of exhaust manifold mounting bolts under high temperature environment. The method obtains the relationship curve between the high temperature axial force of the mounting bolt and the local strain of the rod by conducting a high temperature tensile test on the internal combustion engine exhaust manifold mounting bolt, and then calculates the remaining clamping force of the mounting bolt under high temperature environment assembly conditions based on the curve.

[0020] In one embodiment, reference is made to Figure 1 , Figure 1 This is a flowchart illustrating the evaluation method for the clamping force variation of the exhaust manifold mounting bolts in this application. Figure 1 As shown, the evaluation method for changes in the clamping force of the exhaust manifold mounting bolts includes: S1: The axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures were measured, as well as the strain elongation of the mounting bolt shank at the operating temperature. S2: Tighten the mounting bolts and the clamped parts to form a bolted connection, and combine the axial force-strain relationship curve to obtain the axial clamping force of the mounting bolts in the bolted connection under room temperature conditions; S3: Control the temperature rise of the bolted connection body to measure the strain elongation of the bolt shank in the bolted connection body at the working temperature, and combine the strain elongation of the bolt shank at the working temperature to obtain the remaining strain elongation; S4: Based on the remaining strain elongation and the axial force-strain relationship curve, the remaining axial clamping force is obtained and compared with the axial clamping force of the bolts installed in the bolted connection under room temperature conditions to evaluate the change in clamping force.

[0021] Furthermore, in one embodiment, the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures are measured, specifically including: S101: Use a high-temperature tensile testing machine to perform axial force and rod strain calibration tests on the mounting bolts of the exhaust manifold, and keep the thread engagement length of the mounting bolts on the test fixture consistent with the actual working environment; S102: Install a high-temperature extensometer on the part of the mounting bolt shank that is exposed in the test fixture. After heating to the target temperature, apply an axial tensile load to the mounting bolt and record the axial force and the strain value of the mounting bolt shank during the tensile process. S103: The axial force-strain relationship curve of the mounting bolt at the current target temperature is obtained by linear fitting, thereby obtaining the axial force-strain relationship curve of the mounting bolt at different temperatures.

[0022] Specifically, a series of axial force and strain calibration tests were conducted on the mounting bolts of the exhaust manifold at different temperatures (at least room temperature and the actual operating temperature of the mounting bolts) using a high-temperature tensile testing machine. For details of the test methods, please refer to [link to relevant documentation]. Figure 2 As shown, the installation of the mounting bolts on the test fixture should ensure that the engagement length of the mounting bolts is consistent with that in the actual working environment. A high-temperature extensometer is installed on the part of the mounting bolt shank that protrudes from the test fixture. After the test temperature is raised to the target temperature, an axial tensile load is applied to the mounting bolts. The test is terminated when the tensile load reaches approximately 80% to 90% of the bolt specimen proportional limit. The axial force and the corresponding shank strain value during the tensile process are recorded. Then, a complete axial force-strain relationship curve of the mounting bolt under the current temperature conditions is plotted using linear fitting, thereby obtaining the axial force-strain relationship curve of the mounting bolt at different temperatures.

[0023] Furthermore, in one embodiment, the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures, and the strain elongation of the mounting bolt shank at the operating temperature are measured. Specifically, the measurement of the strain elongation of the mounting bolt shank at the operating temperature includes: S111: Place the mounting bolt into the high-temperature furnace and install a high-temperature extensometer on the shank of the mounting bolt; S112: Gradually raise the temperature to the working temperature of the mounting bolt and maintain it. Measure the strain elongation of the mounting bolt shank using a high-temperature extensometer to obtain the strain elongation of the mounting bolt shank at the working temperature.

[0024] For details, see Figure 3 As shown, individual mounting bolt specimens are placed in a high-temperature furnace, and a high-temperature extensometer is installed on the bolt shank. The temperature is slowly increased to the predetermined working temperature and kept stable for a period of time to ensure uniform temperature distribution. Then, the strain elongation of the bolt shank is monitored in real time by the high-temperature extensometer. This strain elongation is caused by the thermal expansion of the mounting bolt itself, that is, the thermal strain of the mounting bolt body under this high-temperature environment.

[0025] Furthermore, in one embodiment, tightening the mounting bolts and the clamped components forms a bolted connection, and by combining the axial force-strain relationship curve, the axial clamping force of the mounting bolts in the bolted connection under room temperature conditions is obtained, specifically including: S201: Under room temperature conditions, tighten the mounting bolts and the clamped parts of the mounting bolts according to the standard torque or rotation method to obtain a bolted connection body; S202: Measure the strain of the bolt shank in the bolted connection and substitute it into the axial force-strain relationship curve under room temperature conditions. The obtained axial force is the axial clamping force of the bolt in the bolted connection under room temperature conditions.

[0026] Specifically, under normal temperature conditions (i.e., room temperature conditions), the mounting bolts and the clamped parts are tightened according to the standard torque or angle method to obtain the bolted connection body, such as... Figure 4 As shown, the material of the clamped part is the same as the material of the connected part under actual working conditions. The strain of the bolt rod in the bolted connection body is measured at this time. The strain is substituted into the axial force-strain relationship curve under room temperature conditions obtained in step S1. The corresponding axial force is the axial clamping force generated after the bolt is tightened under room temperature conditions.

[0027] Furthermore, in one embodiment, controlling the temperature rise of the bolted connection body to measure the strain elongation of the bolt shank portion of the bolted connection body at the operating temperature specifically includes: The bolted connection body is placed in a high-temperature furnace and gradually heated to the working temperature and maintained. The strain of the bolt shank in the bolted connection body is measured to obtain the strain elongation of the bolt shank in the bolted connection body at the working temperature.

[0028] Specifically, the assembled bolted connection is placed in a high-temperature furnace and slowly heated to the predetermined working temperature. The temperature is then kept stable for a period of time to ensure uniform temperature distribution. Then, the strain elongation of the bolt rod in the bolted connection is monitored in real time using a high-temperature extensometer on a high-temperature tensile testing machine. This strain elongation consists of the thermal expansion elongation of the bolt itself, as well as the elastic elongation and creep elongation of the bolt under clamping force.

[0029] Furthermore, in one embodiment, the remaining strain elongation is obtained by combining the strain elongation of the mounting bolt shank at the operating temperature, specifically including: The difference between the strain elongation of the bolt shank in the bolted connection at the operating temperature and the strain elongation of the bolt shank at the operating temperature is calculated. The result is the residual strain elongation at the operating temperature, which is the residual strain elongation caused by the residual clamping force at high temperature.

[0030] Furthermore, in one embodiment, based on the remaining strain elongation and the axial force-strain relationship curve, the remaining axial clamping force is obtained and compared with the axial clamping force of the bolts installed in the bolted connection at room temperature to evaluate the change in clamping force, specifically including: S401: Substitute the remaining strain elongation as the strain variable into the axial force-strain relationship curve at the working temperature, and the resulting axial force is the remaining axial clamping force at the working temperature. S402: Based on the remaining axial clamping force at the operating temperature and the axial clamping force of the bolts installed in the bolted connection at room temperature, the attenuation rate of the axial clamping force at the operating temperature is calculated to evaluate the change in clamping force.

[0031] Specifically, the remaining strain elongation is used as the strain variable (for example, if the remaining strain elongation is 0.02, then the strain variable is 0.02). This strain variable is then substituted into the axial force-strain relationship curve obtained above at the working temperature. The resulting axial force is the remaining axial clamping force at the working temperature. By comparing this remaining axial clamping force with the axial clamping force of the bolt in the bolted connection under room temperature conditions obtained in step S2, the attenuation rate of the axial clamping force at the working temperature can be obtained, thereby realizing the evaluation of the change in the clamping force of the bolt.

[0032] Specifically, the calculation of the axial clamping force attenuation rate at operating temperature is as follows: a = 1 - F(T1) / F0 Where a represents the attenuation rate of axial clamping force at operating temperature, F(T1) represents the remaining axial clamping force at operating temperature, and F0 represents the axial clamping force of the bolts installed in the bolted connection at room temperature.

[0033] The following example illustrates the evaluation method for the clamping force variation of the exhaust manifold mounting bolts in this application.

[0034] Suppose we need to test the clamping force decay of the exhaust manifold mounting bolts of a certain engine model at an operating temperature of 750℃. The specific conditions are: the exhaust manifold material is heat-resistant ductile iron, the cylinder head material is vermicular graphite cast iron, the exhaust manifold mounting bolt material is a certain iron-nickel-chromium-based high-temperature alloy, and the thread specification is M10.

[0035] First, prepare the connector test piece. Design the connector according to the characteristics of the exhaust manifold mounting bolts on the internal combustion engine. Specifically, based on the structural characteristics of the clamped position of the exhaust manifold, make a simulated heat-resistant ductile iron clamping part. Based on the thread hole characteristics of the exhaust manifold mounting bolts on the cylinder head, make a simulated vermicular graphite cast iron nut.

[0036] Then, the axial force-strain relationship curve of the exhaust manifold mounting bolts was calibrated at the working temperature. The M10 bolt was clamped in a high-temperature tensile testing machine, and a high-temperature extensometer was installed on the bolt shank. The temperature was raised to 750℃ and held for 20 minutes to conduct a high-temperature tensile test, obtaining the axial force-deformation relationship curve under the 750℃ high-temperature condition: F(T) = 175290ε + 3138.4, in N. The relationship curve is shown below. Figure 5As shown, Figure 5 In the context of deformation (i.e., deformation amount), strain (i.e., strain variable) is referred to.

[0037] Then, the high-temperature thermal expansion deformation of the bolt was measured. The bolt, with a high-temperature extensometer installed on its rod, was placed in the high-temperature furnace of a high-temperature tensile testing machine and heated to 750℃. The high-temperature expansion deformation curve was obtained as follows: Figure 6 As shown, its value Δε(t)0 = 0.4021 mm, that is, the strain elongation of the bolt rod at the working temperature is 0.4021 mm.

[0038] Then, the room temperature clamping force of the bolted connection was measured. The bolted connection, consisting of an M10 bolt, a heat-resistant ductile iron clamping element, and a vermicular graphite cast iron nut, was repeatedly tightened five times at room temperature. The average bolt elongation was obtained as 0.236 mm. The room temperature elastic modulus of the bolt was taken as E = 2.0 × 10⁻⁶. 5 MPa, the calculated axial clamping force at room temperature is 34.1 kN.

[0039] Then, high-temperature deformation measurement of the bolted connection is performed. The bolted connection, which has been tightened in the previous step, is placed in a high-temperature furnace and slowly heated to the predetermined working temperature of 750℃. The high-temperature deformation curve is obtained as shown in the figure. Figure 7 As shown, the strain elongation of the bolt shank under clamping condition is Δε(t)1=0.4745mm, that is, the strain elongation of the bolt shank in the bolted connection body at the working temperature is 0.4745mm.

[0040] Finally, the residual clamping force at high temperature is calculated. Based on the strain elongation of the bolt shank in the bolted connection at the working temperature and the strain elongation of the bolt shank at the working temperature, the residual strain elongation Δε(t) caused by the residual clamping force at high temperature can be obtained. r =Δε(t)1-Δε(t)0=0.4745mm-0.4021mm=0.0724mm. Substituting this into the axial force-deformation relationship curve under 750℃ high temperature conditions, we can solve for the remaining axial clamping force F(T1) of the connecting bolt at 750℃, which is 15.8kN. Compared with the axial clamping force of 34.1kN obtained at room temperature, it can be seen that the clamping force is reduced by 53.7% under 750℃ high temperature conditions.

[0041] The exhaust manifold mounting bolt clamping force variation evaluation method of this application embodiment can more accurately reflect the clamping force attenuation of the exhaust manifold mounting bolt under actual working conditions, improve the reliability and accuracy of measurement results, and provide valuable data support for engineers by testing and analyzing bolts of different materials and structural forms, helping them to better select appropriate materials and design parameters, thereby improving the overall performance of the product and ensuring the safe operation of the equipment. At the same time, accurately grasping the variation law of bolt clamping force helps to prevent safety accidents caused by insufficient clamping force and ensure the long-term stable operation of related mechanical equipment.

[0042] Secondly, embodiments of this application also provide a device for evaluating the change in clamping force of exhaust manifold mounting bolts.

[0043] In one embodiment, reference is made to Figure 8 , Figure 8 This is a schematic diagram of the functional modules of the exhaust manifold mounting bolt clamping force variation evaluation device of this application. Figure 8 As shown, the exhaust manifold mounting bolt clamping force variation evaluation device includes: a measurement module, a determination module, an execution module, and an evaluation module.

[0044] The measurement module measures the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures, as well as the strain elongation of the bolt shank at the operating temperature. The determination module tightens the mounting bolts and their clamped components to form a bolted connection, and, based on the axial force-strain relationship curves, obtains the axial clamping force of the mounting bolts in the bolted connection at room temperature. The execution module controls the temperature rise of the bolted connection to measure the strain elongation of the bolt shank at the operating temperature, and, based on the strain elongation of the bolt shank at the operating temperature, obtains the remaining strain elongation. The evaluation module, based on the remaining strain elongation and the axial force-strain relationship curves, obtains the remaining axial clamping force and compares it with the axial clamping force of the mounting bolts in the bolted connection at room temperature, thus evaluating the change in clamping force.

[0045] Thirdly, embodiments of this application provide an evaluation device for changes in the clamping force of exhaust manifold mounting bolts. The evaluation device for changes in the clamping force of exhaust manifold mounting bolts can be a personal computer (PC), a laptop computer, a server, or other devices with data processing capabilities.

[0046] Reference Figure 9 , Figure 9 This is a schematic diagram of the hardware structure of the exhaust manifold mounting bolt clamping force variation evaluation device involved in the embodiments of this application. In this embodiment, the exhaust manifold mounting bolt clamping force variation evaluation device may include a processor, a memory, a communication interface, and a communication bus.

[0047] The communication bus can be of any type and is used to interconnect the processor, memory, and communication interface.

[0048] The communication interface includes input / output (I / O) interfaces, physical interfaces, and logical interfaces for interconnecting internal components of the exhaust manifold mounting bolt clamping force variation evaluation device, as well as interfaces for interconnecting the device with other devices (such as other computing devices or user equipment). Physical interfaces can be Ethernet interfaces, fiber optic interfaces, ATM interfaces, etc.; user equipment can be displays, keyboards, etc.

[0049] Memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0050] The processor can be a general-purpose processor, which can call the exhaust manifold mounting bolt clamping force change evaluation program stored in the memory and execute the exhaust manifold mounting bolt clamping force change evaluation method provided in the embodiments of this application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the exhaust manifold mounting bolt clamping force change evaluation program is called can refer to the various embodiments of the exhaust manifold mounting bolt clamping force change evaluation method of this application, and will not be repeated here.

[0051] Those skilled in the art will understand that Figure 9 The hardware structure shown does not constitute a limitation of this application and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0052] The terms "comprising" and "having," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus. The terms "first," "second," and "third," etc., are used to distinguish different objects, etc., and do not indicate a sequence, nor do they limit "first," "second," and "third" to different types.

[0053] In the description of the embodiments of this application, terms such as "exemplary," "for example," or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary," "for example," or "for instance" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary," "for example," or "for instance" is intended to present the relevant concepts in a concrete manner.

[0054] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0055] In some processes described in the embodiments of this application, multiple operations or steps are included in a specific order. However, it should be understood that these operations or steps may not be executed in the order they appear in the embodiments of this application, or they may be executed in parallel. The sequence number of the operation is only used to distinguish different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed sequentially or in parallel, and these operations or steps may be combined.

[0056] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device to execute the methods described in the various embodiments of this application.

[0057] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An exhaust manifold mounting bolt clamping force variation evaluation method characterized by, The method for evaluating the change in clamping force of the exhaust manifold mounting bolts includes: The axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures were measured, as well as the strain elongation of the mounting bolt shank at the operating temperature. Tighten the mounting bolts and the clamped parts to form a bolted connection body, and combine the axial force-strain relationship curve to obtain the axial clamping force of the mounting bolts in the bolted connection body under room temperature conditions; The temperature of the bolted connection body is controlled to measure the strain elongation of the bolt shank in the bolted connection body at the working temperature. The remaining strain elongation is obtained by combining the strain elongation of the bolt shank in the bolted connection body at the working temperature. Based on the remaining strain elongation and the axial force-strain relationship curve, the remaining axial clamping force is obtained and compared with the axial clamping force of the bolts installed in the bolted connection under room temperature conditions, so as to realize the evaluation of the clamping force change.

2. The method for evaluating the change in clamping force of exhaust manifold mounting bolts as described in claim 1, characterized in that, The measurements obtained the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures, specifically including: A high-temperature tensile testing machine was used to perform axial force and rod strain calibration tests on the mounting bolts of the exhaust manifold, and the thread engagement length of the mounting bolts on the test fixture was kept consistent with that in the actual working environment. A high-temperature extensometer is installed on the part of the mounting bolt shank that is exposed in the test fixture. After the temperature is raised to the target temperature, an axial tensile load is applied to the mounting bolt, and the axial force and the strain value of the mounting bolt shank are recorded during the tensile process. Linear fitting was used to obtain the axial force-strain relationship curve of the mounting bolt at the current target temperature, thereby obtaining the axial force-strain relationship curve of the mounting bolt at different temperatures.

3. The method for evaluating the change in clamping force of exhaust manifold mounting bolts as described in claim 1, characterized in that, The measurements yielded axial force-strain curves for the exhaust manifold mounting bolts at different temperatures, as well as the strain elongation of the bolt shank at operating temperature. Specifically, the measurement of the strain elongation of the bolt shank at operating temperature included: Place the mounting bolts into the high-temperature furnace and install a high-temperature extensometer on the shank of the mounting bolts; The temperature is gradually increased to the working temperature of the mounting bolt and maintained. The strain elongation of the mounting bolt shank is measured by a high-temperature extensometer to obtain the strain elongation of the mounting bolt shank at the working temperature.

4. The method for evaluating the change in clamping force of exhaust manifold mounting bolts as described in claim 1, characterized in that, The tightened mounting bolts and the clamped components form a bolted connection. Based on the axial force-strain relationship curve, the axial clamping force of the mounting bolts in the bolted connection under room temperature conditions is obtained, specifically including: Under room temperature conditions, tighten the mounting bolts and the clamped parts of the mounting bolts according to the standard torque or rotation method to obtain the bolted connection body; The strain of the bolt shank in the bolted connection is measured and substituted into the axial force-strain relationship curve under room temperature conditions. The resulting axial force is the axial clamping force of the bolt in the bolted connection under room temperature conditions.

5. The method for evaluating the change in clamping force of exhaust manifold mounting bolts as described in claim 1, characterized in that, The method of controlling the temperature rise of the bolted connection body to measure the strain elongation of the bolt shank portion in the bolted connection body at the operating temperature specifically includes: The bolted connection body is placed in a high-temperature furnace and gradually heated to the working temperature and maintained. The strain of the bolt shank in the bolted connection body is measured to obtain the strain elongation of the bolt shank in the bolted connection body at the working temperature.

6. The method for evaluating the change in clamping force of exhaust manifold mounting bolts as described in claim 1, characterized in that, The remaining strain elongation is obtained by combining the strain elongation of the mounting bolt shank at the operating temperature, specifically including: The remaining strain elongation at the operating temperature is calculated by subtracting the strain elongation of the bolt shank in the bolted connection from the strain elongation of the bolt shank at the operating temperature.

7. The method for evaluating the change in clamping force of exhaust manifold mounting bolts as described in claim 1, characterized in that, Based on the remaining strain elongation and the axial force-strain relationship curve, the remaining axial clamping force is obtained and compared with the axial clamping force of the bolts in the bolted connection at room temperature to evaluate the change in clamping force. Specifically, this includes: Substituting the remaining strain elongation as the strain variable into the axial force-strain relationship curve at the operating temperature, the resulting axial force is the remaining axial clamping force at the operating temperature. Based on the remaining axial clamping force at operating temperature and the axial clamping force of the bolts installed in the bolted connection at room temperature, the attenuation rate of the axial clamping force at operating temperature is calculated to evaluate the change in clamping force.

8. The method for evaluating the change in clamping force of exhaust manifold mounting bolts as described in claim 7, characterized in that, The calculation of the axial clamping force attenuation rate at operating temperature is as follows: a = 1 - F(T1) / F0 Where a represents the attenuation rate of axial clamping force at operating temperature, F(T1) represents the remaining axial clamping force at operating temperature, and F0 represents the axial clamping force of the bolts installed in the bolted connection at room temperature.

9. A device for evaluating the change in clamping force of exhaust manifold mounting bolts, characterized in that, The exhaust manifold mounting bolt clamping force variation evaluation device includes: The measurement module is used to measure the axial force-strain relationship curves of the exhaust manifold mounting bolts at different temperatures, as well as the strain elongation of the mounting bolt shank at the operating temperature. The module is used to tighten the mounting bolts and the clamped parts to form a bolted connection, and by combining the axial force-strain relationship curve, the axial clamping force of the mounting bolts in the bolted connection under room temperature conditions is obtained. The execution module is used to control the temperature rise of the bolted connection body to measure the strain elongation of the bolt shank in the bolted connection body at the working temperature, and to obtain the remaining strain elongation by combining the strain elongation of the bolt shank at the working temperature. The evaluation module is used to obtain the remaining axial clamping force based on the remaining strain elongation and the axial force-strain relationship curve, and compare it with the axial clamping force of the bolts installed in the bolted connection under room temperature conditions, so as to evaluate the change in clamping force.

10. A device for evaluating the change in clamping force of exhaust manifold mounting bolts, characterized in that, The exhaust manifold mounting bolt clamping force variation evaluation device includes a processor, a memory, and an exhaust manifold mounting bolt clamping force variation evaluation program stored in the memory and executable by the processor, wherein when the exhaust manifold mounting bolt clamping force variation evaluation program is executed by the processor, the steps of the exhaust manifold mounting bolt clamping force variation evaluation method as described in any one of claims 1 to 8 are implemented.

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