Bolt assembly part pre-tightening force detection device
By designing a bolt assembly preload detection device, the preload is calculated using the axial deformation of the elastic sleeve, which solves the problem of the inability to detect bolt preload changes in real time in the existing technology, thus improving detection efficiency and accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI AIRCRAFT MFG
- Filing Date
- 2025-05-19
- Publication Date
- 2026-04-21
AI Technical Summary
Existing technologies cannot detect changes in bolt preload during fatigue testing in real time, resulting in low testing efficiency.
A preload detection device for bolt assembly was designed, including a fatigue loading mechanism and a preload detection mechanism. The fixed head is driven to move along the loading direction by a driving component, and the preload is calculated by the axial deformation of the elastic sleeve. The changes in preload are detected in real time by combining a deformation sensor, a conversion component and a signal processor.
It enables real-time monitoring of bolt preload, improves testing efficiency, allows for timely understanding of preload decay, and avoids over-testing.
Smart Images
Figure CN224151871U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of mechanical performance testing equipment, and in particular to a device for detecting the preload force of bolt assembly. Background Technology
[0002] Mechanical connections are one of the most critical aspects of aircraft manufacturing. Large passenger aircraft manufacturing involves approximately 1.5 to 2 million connecting parts, and mechanical connections, as the primary structural connection method, account for about 70% of the total assembly workload. The pre-processing of drilling for mechanical connections leads to structural discontinuities, causing stress concentration effects when loads are transferred. Under cyclic loading, these stress concentration points are prone to fatigue cracking, leading to structural failure.
[0003] Bolts are one of the most widely used fasteners in aircraft structural assembly. During the tightening process, the preload generated by bolts and nuts changes the stress distribution around the connection hole and reduces the transmitted load through friction, which can effectively improve the fatigue life of the joint. Bolts and nuts are one of the important factors affecting the fatigue life of bolted connections.
[0004] Bolt preload is prone to decay under fatigue load, which in turn affects the fatigue life of bolted connections. Therefore, the decay rate of bolt preload under fatigue load is one of the important evaluation indicators of the fatigue performance of bolted connections.
[0005] Currently, when testing this indicator, the measured value of the tightening torque after the fatigue test is compared with the tightening torque during assembly to evaluate the preload decay. The disadvantage of this method is that it cannot detect the change of preload during the fatigue test in real time. There is a situation where the preload decay reaches the maximum design requirement during the test, but it cannot be detected in time, resulting in the test continuing and thus reducing the test efficiency. Utility Model Content
[0006] The purpose of this invention is to provide a bolt assembly preload detection device to solve the problem in related technologies that cannot detect changes in bolt preload during fatigue testing in real time, resulting in low detection efficiency.
[0007] This utility model provides a bolt assembly preload testing device for testing bolt assemblies, wherein the bolt assembly includes a bolt and a nut, the bolt passing sequentially through a first test piece and a second test piece and being screwed onto the nut, characterized in that it includes:
[0008] A fatigue loading mechanism includes a driving component, a first fixing head, and a second fixing head. The first fixing head and the second fixing head are spaced apart along the loading direction. The driving component drives the first fixing head and / or the second fixing head to move along the loading direction. The first fixing head is used to fix the first test piece, and the second fixing head is used to fix the first test piece or the second test piece.
[0009] A preload detection mechanism includes an elastic sleeve and a detection component. The elastic sleeve is used to fit onto the bolt, and both ends of the elastic sleeve are respectively pressed against the second test piece and the nut. The detection component can detect the axial deformation of the elastic sleeve to calculate the preload force on the elastic sleeve through the axial deformation of the elastic sleeve.
[0010] As a preferred technical solution for the bolt assembly preload detection device, the detection component includes a deformation sensor, a conversion element, and a signal processor. The deformation sensor is attached to the peripheral wall of the elastic sleeve and converts the axial deformation of the elastic sleeve into a change in resistance. The conversion element is used to convert the change in resistance of the deformation sensor into a voltage signal, and the signal processor is used to communicate with the conversion element.
[0011] As a preferred technical solution for the bolt assembly preload detection device, the conversion component is a Wheatstone bridge.
[0012] As a preferred technical solution for the preload detection device for bolt assembly, at least two deformation sensors are provided, and the at least two deformation sensors are arranged at circumferential intervals around the elastic sleeve.
[0013] As a preferred technical solution for the bolt assembly preload detection device, the elastic sleeve is a seamless sleeve.
[0014] As a preferred technical solution for the bolt assembly preload testing device, the first fixing head is a clamping member used to clamp one end of the first test piece, and the second fixing head is a clamping member used to clamp the other end of the first test piece or the second test piece.
[0015] As a preferred technical solution for the preload detection device for bolt assembly, the fatigue loading mechanism further includes a bracket, the first fixing head is connected to the bracket, the second fixing head is slidably disposed on the bracket along the loading direction, and the driving member drives the second fixing head to slide relative to the bracket.
[0016] As a preferred technical solution for the bolt assembly preload detection device, the driving component is a hydraulic cylinder, one end of which is fixedly connected to the bracket, and the other end of which is fixedly connected to the second fixed head.
[0017] As a preferred technical solution for the bolt assembly preload detection device, the fatigue loading mechanism further includes a force gauge, which is used to connect the first fixing head and the bracket.
[0018] As a preferred technical solution for the bolt assembly preload detection device, it also includes an audible and visual alarm, which is used to communicate with the detection component.
[0019] The beneficial effects of this utility model are as follows:
[0020] This utility model provides a bolt assembly preload detection device for testing bolt assemblies, which include bolts and nuts. The bolt passes through a first test piece and a second test piece in sequence and is screwed to the nut. The bolt assembly preload detection device includes a fatigue loading mechanism and a preload detection mechanism. The fatigue loading mechanism includes a driving component, a first fixing head, and a second fixing head. The first fixing head and the second fixing head are spaced apart along the loading direction. The driving component drives the first fixing head and / or the second fixing head to move along the loading direction. The first fixing head is used to fix the first test piece, and the second fixing head is used to fix either the first test piece or the second test piece. The preload detection mechanism includes an elastic sleeve and a detection component. The elastic sleeve is used to fit onto the bolt, and both ends of the elastic sleeve are respectively abutted against the second test piece and the nut. The detection component can detect the axial deformation of the elastic sleeve to calculate the preload force on the elastic sleeve through the axial deformation of the elastic sleeve. The driving component cyclically loads the first and / or second fixed heads along the loading direction, causing deformation of the first and / or second test pieces at the bolt assembly location. This deformation, in turn, causes the elastic sleeve to elastically deform along the bolt's axial direction. The detection component detects this axial deformation of the elastic sleeve and calculates the preload force on it, which is the preload force of the bolt assembly. By comparing this preload force with the preload force before testing, the real-time preload decay of the bolt assembly can be obtained, thus improving detection efficiency. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the preload force detection device for bolt assembly in this embodiment of the present invention. Figure 1 ;
[0022] Figure 2 This is a schematic diagram of the preload force detection device for bolt assembly in this embodiment of the present invention. Figure 2 .
[0023] In the picture:
[0024] 100. Bolt assembly; 101. Bolt; 102. Nut;
[0025] 200, First test specimen; 300, Second test specimen;
[0026] a. Loading direction;
[0027] 11. First fixing head; 12. Second fixing head; 13. Driving component; 14. Bracket; 141. Base; 142. Slide rail; 15. Force gauge;
[0028] 21. Elastic sleeve; 221. Deformation sensor; 222. Converter; 223. Signal processor. Detailed Implementation
[0029] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.
[0030] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and for simplifying the description, 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 limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Moreover, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0032] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.
[0033] Example 1
[0034] like Figure 1 As shown, this embodiment provides a bolt assembly preload testing device for testing a bolt assembly 100. The bolt assembly 100 includes a bolt 101 and a nut 102. The bolt 101 passes through a first test piece 200 and a second test piece 300 in sequence and is screwed to the nut 102. The bolt assembly preload testing device includes a fatigue loading mechanism and a preload testing mechanism. The fatigue loading mechanism includes a driving member 13, a first fixing head 11, and a second fixing head 12. The first fixing head 11 and the second fixing head 12 are spaced apart along the loading direction a. The driving member 13... 3. Drive the first fixing head 11 and / or the second fixing head 12 to move along the loading direction a. The first fixing head 11 is used to fix the first test piece 200, and the second fixing head 12 is used to fix the first test piece 200. The preload detection mechanism includes an elastic sleeve 21 and a detection component. The elastic sleeve 21 is used to be sleeved on the bolt 101, and the two ends of the elastic sleeve 21 are respectively abutted against the second test piece 300 and the nut 102. The detection component can detect the axial deformation of the elastic sleeve 21 so as to calculate the preload on the elastic sleeve 21 through the axial deformation of the elastic sleeve 21.
[0035] Taking the first fixing head 11 and the second fixing head 12 fixing the two ends of the first test piece 200 respectively as an example, the first fixing head 11 and / or the second fixing head 12 are driven by the driving component 13 to perform cyclic loading along the loading direction a, thereby causing the first test piece 200 and / or the second test piece 300 to deform at the location where the bolt assembly 100 is set, which in turn causes the elastic sleeve 21 to undergo elastic deformation along the axial direction of the bolt 101. The detection component can detect the axial deformation of the elastic sleeve 21, and calculate the preload force on the elastic sleeve 21 through the axial deformation of the elastic sleeve 21, which is the preload force of the bolt assembly 100. By comparing this preload force with the preload force before the test, the real-time preload force decay of the bolt assembly 100 can be obtained, thereby improving the efficiency of the detection.
[0036] Specifically, the cyclic loading is the alternating action of the drive member 13 causing the first fixed head 11 and the second fixed head 12 to move closer to each other and further apart.
[0037] Optionally, the detection component includes a deformation sensor 221, a converter 222, and a signal processor 223. The deformation sensor 221 is attached to the peripheral wall of the elastic sleeve 21, converting the axial deformation of the elastic sleeve 21 into a change in resistance. The converter 222 converts the change in resistance of the deformation sensor 221 into a voltage signal. The signal processor 223 is used for communication with the converter 222. In this embodiment, the preload formula can be obtained based on the mechanical property parameters of the sleeve material and the axial load of the hollow rod: F = E·ε·A, where F is the preload, E is the elastic modulus of the sleeve material, ε is the strain value, and A is the cross-sectional area of the sleeve.
[0038] For the strain value ε, the formula is used. The result is obtained, where GF is the sensitivity coefficient of the deformation sensor, ε is the strain value, e0 is the voltage drop, and Eex is the excitation voltage. e0 and Eex can be obtained from the obtained voltage signal.
[0039] Optionally, the converter 222 is a Wheatstone bridge. In this embodiment, the Wheatstone bridge can convert the change in resistance into the change in voltage, which is existing technology and will not be described in detail here.
[0040] Optionally, at least two deformation sensors 221 are provided, with at least two deformation sensors 221 arranged circumferentially around the elastic sleeve 21. In this embodiment, by arranging the deformation sensors 221 at different spatial positions, the data differences at each position can be compared to identify and compensate for external interference, thereby improving the accuracy of the data.
[0041] Optionally, the elastic sleeve 21 is a seamless sleeve. In this embodiment, this feature can improve the uniformity of deformation of the elastic sleeve 21 and prevent skewing or other issues.
[0042] Optionally, the first fixing head 11 is a clamping member used to clamp one end of the first test piece 200, and the second fixing head 12 is a clamping member used to clamp the other end of the first test piece 200 or the second test piece 300. In this embodiment, both the first fixing head 11 and the second fixing head 12 are designed as clamping members. This design facilitates disassembly and can accommodate test pieces of different sizes.
[0043] Optionally, the fatigue loading mechanism further includes a bracket 14, with a first fixing head 11 connected to the bracket 14 and a second fixing head 12 slidably disposed on the bracket 14 along the loading direction a. A driving member 13 drives the second fixing head 12 to slide relative to the bracket 14. In this embodiment, the bracket 14 includes a base 141 and a slide rail 142 disposed on the base 141. The slide rail 142 extends along the loading direction a. The first fixing head 11 is connected to the base 141, and the second fixing head 12 slidably engages with the slide rail 142 along the loading direction a.
[0044] Optionally, the driving component 13 is a hydraulic cylinder, with one end fixedly connected to the bracket 14 and the other end fixedly connected to the second fixed head 12. In this embodiment, the cylinder body of the hydraulic cylinder is fixedly connected to the end of the slide rail 142 away from the base 141, and the telescopic end of the hydraulic cylinder is fixedly connected to the second fixed head 12. In other embodiments, the driving component 13 may also include a lead screw, a nut 102, a guide rod, and a drive motor. The lead screw is disposed on the slide rail 142, its axis extends along the loading direction a, and the lead screw can rotate around its axis. The nut 102 is sleeved on the lead screw and fixedly connected to the second fixed head 12. The drive motor drives the lead screw to rotate. The guide rod is fixedly disposed on the base 141, and its axis extends along the loading direction a. The nut 102 is sleeved on the guide rod and slides with the guide rod.
[0045] Optionally, the fatigue loading mechanism further includes a force gauge 15, which connects the first fixed head 11 and the bracket 14. In this embodiment, the force gauge 15 is fixed on the base 141 of the bracket 14, and the measuring head of the force gauge 15 is connected to the first fixed head 11. The force gauge 15 can be used to observe the loading force between the first fixed head 11 and the second fixed head 12, and can verify whether the actual loading force is consistent with the preset loading force.
[0046] Optionally, the bolt assembly preload detection device also includes an audible and visual alarm, which is used to communicate with the detection component. In this embodiment, when the preload of the bolt assembly 100 decreases to a preset maximum value, the signal processor 223 of the detection component transmits the signal to the audible and visual alarm, which then sounds an alarm to remind the staff that the test is over.
[0047] Specifically, the preload reduction value r of bolt assembly 100 is (F 前 -F 实 ) / F 前 , where F 前 F represents the magnitude of the preload force before the bolt assembly preload force detection device begins to apply the loading force. 实 The magnitude of the preload at a certain moment during the application of loading force to the bolt assembly preload detection device. When r > a, it indicates that the preload decay of bolt assembly 100 has reached the preset maximum value. The value range of a is: 1% < a < 50%.
[0048] Example 2
[0049] like Figure 2 As shown, this embodiment is basically the same as embodiment one, except that the first fixing head 11 and the second fixing head 12 fix the first test piece 200 and the second test piece 300 respectively. The operation steps and effects are the same as those of fixing the two ends of the first test piece 200 with the first fixing head 11 and the second fixing head 12 respectively, and will not be described again here.
[0050] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.
Claims
1. A bolt assembly pre-tightening force detection device for detecting a bolt assembly (100) including a bolt (101) and a nut (102), the bolt (101) being screwed with the nut (102) after sequentially passing through a first test piece (200) and a second test piece (300), characterized in that, include: The fatigue loading mechanism includes a drive member (13), a first fixing head (11) and a second fixing head (12), the first fixing head (11) and the second fixing head (12) being spaced apart along the loading direction (a), the drive member (13) driving the first fixing head (11) and / or the second fixing head (12) to move along the loading direction (a), the first fixing head (11) being used to fix the first test piece (200), and the second fixing head (12) being used to fix the first test piece (200) or the second test piece (300); The preload detection mechanism includes an elastic sleeve (21) and a detection component. The elastic sleeve (21) is used to fit onto the bolt (101), and both ends of the elastic sleeve (21) are respectively pressed against the second test piece (300) and the nut (102). The detection component can detect the axial deformation of the elastic sleeve (21) to calculate the preload force on the elastic sleeve (21) through the axial deformation of the elastic sleeve (21).
2. The bolted joint pretension detection device of claim 1, wherein, The detection component includes a deformation sensor (221), a converter (222), and a signal processor (223). The deformation sensor (221) is attached to the peripheral wall of the elastic sleeve (21). The deformation sensor (221) converts the axial deformation of the elastic sleeve (21) into a change in resistance. The converter (222) is used to convert the change in resistance of the deformation sensor (221) into a voltage signal. The signal processor (223) is used to communicate with the converter (222).
3. The bolted joint pretension detection device of claim 2, wherein, The converter (222) is a Wheatstone bridge.
4. The bolted joint pretension detection device of claim 2, wherein, At least two deformation sensors (221) are provided, and the at least two deformation sensors (221) are arranged circumferentially around the elastic sleeve (21).
5. The bolted joint pretension detection device of claim 1, wherein, The elastic sleeve (21) is a seamless sleeve.
6. The bolted joint pretension detection device of claim 1, wherein, The first fixing head (11) is a clamping member, which is used to clamp one end of the first test piece (200). The second fixing head (12) is a clamping member, which is used to clamp the other end of the first test piece (200) or the second test piece (300).
7. The bolt assembly preload detection device according to claim 1, characterized in that, The fatigue loading mechanism further includes a bracket (14), the first fixing head (11) is connected to the bracket (14), and along the loading direction (a), the second fixing head (12) is slidably disposed on the bracket (14), and the driving member (13) drives the second fixing head (12) to slide relative to the bracket (14).
8. The bolted joint pretension detection device of claim 7, wherein, The driving component (13) is a hydraulic cylinder. One end of the hydraulic cylinder is fixedly connected to the bracket (14), and the other end of the hydraulic cylinder is fixedly connected to the second fixing head (12).
9. The bolted joint pretension detection device of claim 7, wherein, The fatigue loading mechanism also includes a force gauge (15), which is used to connect the first fixing head (11) and the bracket (14).
10. The bolted joint pretension detection device of any one of claims 1-9, wherein, It also includes an audible and visual alarm, which is used to communicate with the detection component.