Bolt friction testing fixture, system, and method

Abstract

This application belongs to the field of friction testing, and particularly relates to a bolt friction testing fixture, system, and method. The bolt friction testing fixture includes: a support plate assembly with a first through hole extending axially; a torque acquisition module spaced axially on one side of the support plate assembly, with the axial end of the torque acquisition module near the support plate assembly serving as a torque input end; and a threaded insert with a second through hole extending axially and including an embedded end and an exposed end; wherein the embedded end is inserted into the first through hole, and the portion of the second through hole at the embedded end is a threaded section, which is threadedly connected to the bolt; the exposed end is located outside the first through hole and connected to the torque input end, and at least a portion of the exposed end can abut against the support plate assembly. The bolt friction testing fixture provided by this application is suitable for friction testing of short bolts, and can measure a wider range of bolt lengths.

Description

Technical Field

[0001] This application belongs to the field of friction testing, and in particular relates to a bolt friction testing fixture, system and method. Background Technology

[0002] As vehicle requirements become increasingly stringent, more and more short bolts are being used. Current standards use horizontal bolt friction testing machines to test the coefficient of friction, including the total coefficient of friction, the thread friction coefficient, and the head friction coefficient.

[0003] In addition to obtaining the total torque and thread torque, the horizontal bolt friction testing machine also needs to obtain the clamping force to evaluate the coefficient of friction. Accordingly, the testing fixture in the horizontal bolt friction testing machine is equipped with a functional component for obtaining the clamping force, which increases the axial fit length between the testing fixture and the bolt, making it difficult to adapt to the friction test of short bolts. Summary of the Invention

[0004] This application provides a bolt friction testing fixture, system, and method to solve the technical problem that existing bolt friction testing solutions require fixtures capable of detecting clamping force, making them difficult to adapt to the testing of the friction coefficient of short bolts.

[0005] This application provides a bolt friction testing fixture, comprising: a support plate assembly having a first through hole extending axially; a torque acquisition module axially spaced on one side of the support plate assembly, wherein the axial end of the torque acquisition module near the support plate assembly is a torque input end; and a threaded insert having a second through hole extending axially and including an embedded end and an exposed end; wherein the embedded end is inserted into the first through hole, and the portion of the second through hole at the embedded end is a threaded hole segment, the threaded hole segment being threadedly connected to a bolt; the exposed end is located outside the first through hole and connected to the torque input end, and at least a portion of the exposed end is capable of abutting against the support plate assembly.

[0006] In an optional embodiment of this application, the first through hole includes a first hole segment and a second hole segment, the diameter of the first hole segment being smaller than the diameter of the second hole segment; the first hole segment is farther away from the torque acquisition module relative to the second hole segment, and an annular surface is formed at the junction of the first hole segment and the second hole segment; when the exposed end abuts against the support plate assembly, there is an axial gap between the end face of the embedded end and the annular surface.

[0007] In an optional embodiment of this application, the support plate assembly includes a support plate and a gasket, both of which have through holes; the gasket is stacked on the surface of the support plate on the side away from the torque acquisition module, and the through hole of the gasket communicates with the through hole of the support plate to form the first through hole.

[0008] In an optional embodiment of this application, the through hole of the gasket is a stepped hole and the inner peripheral wall is formed with an annular surface facing the end face of the embedded end, and the portion of the stepped hole located on the annular surface away from the axial side of the embedded end is a first hole segment.

[0009] In an optional embodiment of this application, the exposed end is provided with an ear plate, which can abut against the support plate assembly.

[0010] In an optional embodiment of this application, the portion of the second through hole at the exposed end position is a polygonal hole segment, and the torque input end is a polygonal column that is embedded in the polygonal hole segment in a shape-fitting manner.

[0011] A second aspect of this application provides a bolt friction testing system, including a torque application shaft, a control module, and the aforementioned bolt friction testing fixture; a bolt is inserted into a first through hole and connected to the embedded end, the torque application shaft is used to apply a total torque to the bolt; the control module is connected to the torque acquisition module and the torque application shaft to obtain the thread torque and the total torque, and calculates the total friction coefficient, the thread friction coefficient, and the head friction coefficient based on the thread torque, the total torque, and bolt specification parameters.

[0012] A third aspect of this application provides a bolt friction testing method, implemented using the aforementioned bolt friction testing system, and including the following steps: The bolt is first screwed in and then unscrewed to obtain tightening torque, loosening torque, thread torque, and head torque, wherein the head torque is the difference between the tightening torque and the thread torque; The total friction coefficient is obtained based on the tightening torque, the loosening torque, the bolt specifications, and the first calculation model, wherein the bolt specifications include the pitch, the thread pitch diameter, and the head friction diameter. The thread friction coefficient is obtained based on the thread torque, the total friction coefficient, the tightening torque, the bolt specification parameters, and the second calculation model. The coefficient of friction under the head is obtained based on the torque under the head, the total coefficient of friction, the tightening torque, the bolt specification parameters, and the third calculation model.

[0013] In an optional embodiment of this application, the first calculation model conforms to the formula: in, The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; This is the anti-loosening torque.

[0014] In an optional embodiment of this application, the second calculation model conforms to the formula: in, The coefficient of friction of the thread; The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; For thread torque; The third calculation model conforms to the formula: in, The coefficient of friction under the head; The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; This refers to the torque at the top.

[0015] In summary, the solution provided in this application has at least the following beneficial effects: The bolt friction testing fixture provided in this application does not require a clamping force sensor. That is, the bolt friction testing fixture does not include a clamping force sensor or a functional component for testing clamping force that requires axial space, thereby reducing the axial space occupation and thus reducing the requirement for the stud length of the bolt, which enables testing of shorter bolts.

[0016] In addition, since the insert end of the threaded insert is embedded in the first through hole, the bolt stud does not need to completely pass through the first through hole, which further reduces the requirement for the bolt stud length.

[0017] Thus, the bolt friction testing fixture provided in this application does not require a functional component for detecting clamping force, reducing axial space occupation, lowering costs, and having low requirements for bolt stud length. It is also compatible with bolt friction testing methods that do not require clamping force parameters, making it suitable for friction testing of short bolts, and thus allowing for a wider range of measurable bolt lengths. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the specific embodiments of this application, the drawings used in the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a bolt friction testing system provided according to one embodiment of this application.

[0020] Figure 2 for Figure 1 A schematic diagram of the tooling for testing the friction of bolts.

[0021] Figure 3 This is a flowchart of the steps of a bolt friction test method provided according to one embodiment of this application.

[0022] Figure label: 100. Bolt friction testing fixture; 11. Support plate assembly; 111. Support plate; 112. Gasket; 101. Annular surface; H1. First through hole; H11. First hole segment; H12. Second hole segment; 12. Torque acquisition module; 121. Torque input terminal; 13. Threaded insert; 131. Ear plate; H2. Second through hole; H21. Threaded hole section; H22. Polygonal hole section; 200, Torque application shaft; 300. Control module; 400. Bolts. Detailed Implementation

[0023] To make the above and other features and advantages of this application clearer, the application is further described below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explanation to those skilled in the art and are exemplary only, not restrictive.

[0024] Furthermore, features specified with "first" or "second" for descriptive purposes only should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Features specified with "first" or "second" may explicitly or implicitly include at least one of the specified features. The description of "multiple" generally means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0025] Figure 1 This is a schematic diagram of a bolt friction testing system provided according to one embodiment of this application. Figure 2 for Figure 1A schematic diagram of the tooling for testing the friction of bolts.

[0026] See Figure 1 and Figure 2 The bolt friction testing system provided in this application includes a bolt friction testing fixture 100, a torque application shaft 200, and a control module 300. The bolt friction testing fixture 100 is used to load bolts 400, the torque application shaft 200 is used to apply torque to the bolts 400 loaded on the bolt friction testing fixture 100, and the control module 300 is used to control the torque provided by the torque application shaft 200 and to obtain data collected from the bolt friction testing fixture 100.

[0027] Furthermore, the bolt friction testing fixture 100 provided in this application includes a support plate assembly 11, a torque acquisition module 12, and a threaded insert 13. The support plate assembly 11 has a first through hole H1 extending axially; the torque acquisition module 12 is axially spaced on one side of the support plate assembly 11, and the axial end of the torque acquisition module 12 near the support plate assembly 11 is a torque input end 121; the threaded insert 13 has a second through hole H2 extending axially and includes an embedded end and an exposed end; wherein, the embedded end is inserted into the first through hole H1, and the portion of the second through hole H2 at the embedded end position is a threaded hole section H21, which is threadedly connected to the bolt 400; the exposed end is located outside the first through hole H1 and connected to the torque input end 121, and at least a portion of the exposed end can abut against the support plate assembly 11.

[0028] For the bolt friction test fixture 100, the support plate assembly 11 is used to provide support. The torque acquisition module 12 is arranged axially spaced from the support plate assembly 11 and is indirectly connected to the bolt 400 through a threaded insert 13 that can extend into the first through hole H1 of the support plate assembly 11. In this way, the torque applied to the bolt 400 is transmitted to the torque acquisition module 12 via the threaded insert 13. The torque acquisition module 12 acquires the thread torque and can be a torque sensor.

[0029] The threaded insert 13 has an embedded end and an exposed end at its two axial ends, respectively. The threaded insert 13 is provided with a second through hole H2 that runs through it along its axial direction. The portion of the second through hole H2 at the embedded end is a threaded hole section H21, which is used to engage with the bolt 400 thread. The portion of the second through hole H2 at the exposed end can be a polygonal hole section H22, which engages with the torque input end 121 through the polygonal hole section H22.

[0030] The embedded end is embedded in the first through hole H1 and is clearance-fitted with the first through hole H1, thereby allowing the embedded end to be inserted into the first through hole H1. Furthermore, since at least a portion of the exposed end can abut against the support plate assembly 11 to prevent the threaded insert 13 from moving axially, torque can only be transmitted to the torque acquisition module 12 when the threaded insert 13 cannot move axially.

[0031] The support plate assembly 11 is clamped between the bolt head and the exposed end, thus applying a clamping force to the support plate assembly 11. In the prior art, the fixture for testing bolt friction is also equipped with a clamping force sensor to obtain the clamping force. However, this increases the axial length of the fixture, and correspondingly, to ensure the engagement length of the bolt 400, the stud length of the bolt 400 needs to be increased. The bolt friction testing fixture 100 provided in this application does not require a clamping force sensor. That is, the bolt friction testing fixture 100 does not include a clamping force sensor or a functional component for testing clamping force that requires axial space, reducing the axial space occupied. Therefore, the stud length requirement of the bolt 400 is reduced, and shorter bolts can be tested.

[0032] In addition, since the insert end of the threaded insert 13 is embedded in the first through hole H1, the stud of the bolt 400 does not need to completely pass through the first through hole H1, which further reduces the requirement for the stud length of the bolt 400.

[0033] Therefore, the bolt friction testing fixture 100 provided in this application does not require a functional component for detecting clamping force, which reduces axial space occupation, lowers costs, and does not have high requirements for the stud length of the bolt 400, making it suitable for friction testing of short bolts, thus allowing for a wider range of measurable bolt lengths.

[0034] In some embodiments, for a system equipped with the bolt friction test fixture 100, the bolt 400 is inserted into the first through hole H1 and connected to the embedded end of the threaded insert 13, and the torque application shaft 200 is used to apply a total torque to the bolt 400.

[0035] The control module 300 connects the torque acquisition module 12 and the torque application shaft 200 to obtain the thread torque and total torque, and calculates the total friction coefficient, thread friction coefficient and head friction coefficient based on the thread torque, total torque and bolt specification parameters.

[0036] In this embodiment, the bolt 400 passes through the first through hole H1 and engages with the threaded section H21 at the embedded end of the threaded insert 13. Mounting the bolt 400 on the bolt friction test fixture 100 means that the bolt 400 and the threaded insert 13 are pre-assembled; that is, the bolt 400 is not fully locked or subjected to the required torque. Furthermore, the bolt specifications include the pitch, thread pitch diameter, and head friction diameter, where the head friction diameter can refer to the average diameter of the inner and outer diameters of the bolt's nut's screw marks on the washer.

[0037] A torque-applying shaft 200 acts on the bolt 400 to apply a total torque to the bolt 400. In an optional embodiment, the torque-applying shaft 200 is equipped with a torque sensor and can record a torque angle curve. It is started and stopped by a control module 300 to screw the bolt 400 in or out and to provide the required total torque. The total torque may include tightening torque and loosening torque, both of which can be obtained from the torque angle curve. It should be noted that the loosening torque is a dynamic point selected based on the torque angle curve, which is the critical point for the transition from static torque to dynamic torque.

[0038] The control module 300 is connected to the torque acquisition module 12 and the torque application shaft 200. It can acquire the thread torque and the total torque, and can control the operation of the torque application shaft 200. The control module 300 is also equipped with a calculation model. The calculation model calculates the total friction coefficient, the thread friction coefficient and the head friction coefficient based on the thread torque, the total torque and the bolt specification parameters.

[0039] Since this system can obtain the friction coefficient of a bolt without requiring additional clamping force, it simplifies the system composition and, together with the bolt friction testing fixture 100, enables the detection of the friction coefficient of short bolts.

[0040] In some embodiments, the first through hole H1 includes a first hole segment H11 and a second hole segment H12, wherein the diameter of the first hole segment H11 is smaller than the diameter of the second hole segment H12.

[0041] The first hole segment H11 is farther away from the torque acquisition module 12 relative to the second hole segment H12, and an annular surface 101 is formed at the junction of the first hole segment H11 and the second hole segment H12.

[0042] When the exposed end of the threaded insert 13 abuts against the support plate assembly 11, there is an axial clearance G between the end face of the inserted end of the threaded insert 13 and the annular surface 101.

[0043] In this embodiment, firstly, the first through hole H1 is a stepped hole, wherein the part with a relatively smaller diameter is the first hole segment H11, and the part with a relatively larger diameter is the second hole segment H12. The second hole segment H12 is used to accommodate the embedded end, that is, the threaded insert 13 is in clearance fit with the second hole segment H12 of the first through hole H1. The first hole segment H11 is relatively small, which ensures that the contact area of ​​the nut of the bolt 400 meets the test requirements and ensures the accuracy of the measurement of the friction coefficient under the head.

[0044] Secondly, when the bolt 400 is tightened, the threaded insert 13 tends to move axially toward the support plate assembly 11. However, since the threaded insert 13 is in contact with the support plate assembly 11, it cannot move axially, thereby transmitting torque to the torque acquisition module 12. In addition, the axial clearance G between the end face of the inserted end and the annular surface 101 avoids friction at the inserted end, ensuring the detection accuracy of the thread friction coefficient.

[0045] In some embodiments, the support plate assembly 11 includes a support plate 111 and a gasket 112, both of which have through holes.

[0046] The gasket 112 is stacked on the surface of the support plate 111 on the side away from the torque acquisition module 12, and the through hole of the gasket 112 is connected to the through hole of the support plate 111 to form a first through hole H1.

[0047] In this embodiment, the support plate assembly 11 may be formed by stacking a support plate 111 and a gasket 112 in the axial direction. Both the support plate 111 and the gasket 112 are provided with through holes. The through holes on the support plate 111 and the through holes on the gasket 112 are aligned in the axial direction to form a first through hole H1.

[0048] Since different specifications of bolts 400 require different washer specifications, the support plate assembly 11 is detachably assembled from a support plate 111 and a washer 112. The through holes of the support plate 111 and the washer 112 mate to form a first through hole H1. Different specifications of washer 112 are used to adapt to different specifications of bolts 400. In other words, the support plate 111 is a universal component, while the washer 112 is a replaceable component adapted to the specifications of bolts 400. Thus, it is not necessary to replace the entire support plate assembly 11 to adapt to different specifications of bolts 400.

[0049] In some embodiments, the through hole of the gasket 112 is a stepped hole and the inner peripheral wall is formed with an annular surface 101 facing the end face of the embedded end, and the portion of the stepped hole located on the axial side of the annular surface 101 away from the embedded end is the first hole segment H11.

[0050] In this embodiment, the through hole of the gasket 112 is a stepped hole and includes a first hole segment H11. The inner peripheral wall of the stepped hole has an annular surface 101, which is the interface between the first hole segment H11 and the second hole segment H12. Thus, the hole segment with a relatively large diameter at the gasket 112 and the through hole at the support plate 111 cooperate to form the second hole segment H12.

[0051] Thus, the depth of the first hole section H11, which has a relatively small diameter, is less than the thickness of the gasket 112, increasing the depth of the second hole section H12. The depth of the second hole section H12 determines the embedding depth of the threaded insert 13. While avoiding contact between the embedding end and the annular surface 101, the embedding end is ensured to have a large embedding depth, thereby maximizing the engagement length of the short bolt 400.

[0052] The diameter of the relatively large hole at the gasket 112 can be equal to or unequal to the diameter of the through hole at the support plate 111, as long as it does not interfere with the insertion of the threaded insert 13.

[0053] In some embodiments, the exposed end is provided with an ear plate 131, which can abut against the support plate assembly 11.

[0054] In this embodiment, the exposed end abuts against the support plate assembly 11 via the ear plate 131 to achieve axial positioning of the threaded insert 13. In practical applications, the contact surfaces of the ear plate 131 and the support plate 111 are flat, reducing the impact of friction between them on torque transmission and ensuring the measurement accuracy of the thread torque.

[0055] In some embodiments, the portion of the second through hole H2 at its exposed end is a polygonal hole segment H22, and the torque input end 121 is a polygonal column that is embedded in the polygonal hole segment H22 in a shape-fitting manner.

[0056] In this embodiment, the polygonal hole segment H22 is fitted with the polygonal columnar torque input end 121, so that the threaded insert 13 and the torque input end 121 cannot rotate relative to each other, thus ensuring the transmission of torque.

[0057] It should be understood that the engagement of the polygonal hole segment H22 with the torque input end 121 restricts the relative rotation of the threaded insert 13 and the torque acquisition module 12. However, it is necessary to ensure that the torque input end 121 can be properly inserted into the polygonal hole segment H22. That is, the threaded insert 13 can move axially relative to the torque acquisition module 12. At the same time, the insertion end of the threaded insert 13 is clearance-fitted with the second hole segment H12. Therefore, the threaded insert 13, the support plate assembly 11, and the torque acquisition module 12 are all detachably engaged. Thus, the threaded insert 13 is a replaceable part to adapt to bolts 400 of different specifications. Specifically, different threaded inserts 13 require threaded hole segments H21 of different sizes to adapt to bolts 400 of different specifications.

[0058] In practical applications, the cross-section of the polygonal hole segment H22 can be rectangular, square, regular pentagon, or regular hexagon, and correspondingly, the cross-section of the torque input end 121 has a corresponding shape.

[0059] Figure 3 This is a flowchart illustrating the steps of a bolt friction testing method according to one embodiment of this application. This application also provides a bolt friction testing method, implemented using the aforementioned bolt friction testing system, and including at least the following steps: S501, first screw in, then screw out the bolt 400 to obtain tightening torque, loosening torque, thread torque and head torque, where head torque is the difference between tightening torque and thread torque; S502, the total friction coefficient is obtained based on the tightening torque, loosening torque, bolt specification parameters and the first calculation model, wherein the bolt specification parameters include the pitch, thread pitch diameter and head friction diameter; S503, the thread friction coefficient is obtained based on the thread torque, total friction coefficient, tightening torque, bolt specification parameters and the second calculation model; S504, the coefficient of friction under the head is obtained based on the torque under the head, the total coefficient of friction, the tightening torque, the bolt specification parameters, and the third calculation model.

[0060] For S501, the tightening torque can be set according to the specifications of bolt 400. For example, bolts with the same thread pitch diameter but different lengths can use a larger tightening torque for bolts with a relatively longer length. The tightening torque can be provided by the torque application shaft 200 driven by the control module 300. Understandably, the loosening torque is opposite in direction to the tightening torque and is basically the same in magnitude.

[0061] In one optional embodiment, the torque application shaft 200 is an electric tightening shaft equipped with a torque sensor. The control module 300 can start the electric tightening shaft, and the torque sensor in the electric tightening shaft can acquire the real-time torque to generate a torque angle curve. Based on the comparison between the real-time torque and the set target total torque, it automatically stops, thereby applying the required target total torque to the bolt 400. During the bolt tightening process, when the control module 300 determines that the acquired real-time torque has reached the target tightening torque, the control module 300 controls the electric tightening shaft to stop operating. During the process of the control module 300 controlling the electric tightening shaft to unscrew the bolt 400, the anti-loosening torque can be obtained through the torque angle curve acquired by the electric tightening shaft.

[0062] In one optional embodiment, the torque application shaft 200 is an electric wrench, and the control module 300 is equipped with a curve showing the relationship between the motor output power and output torque of the electric wrench. The control module 300 sets the total torque and controls the output power of the electric wrench according to the set total torque output command to control the total torque acting on the bolt 400. Compared with a constant torque electric wrench solution, the accuracy deviation of the total torque provided by the electric wrench in this embodiment is lower. Of course, the torque application shaft 200 is not limited to the above; for example, it can also be a constant torque electric wrench.

[0063] As described above, the control module 300 can obtain the thread torque through the torque acquisition module 12, and the torque under the head is the difference between the tightening torque and the thread torque. Therefore, the S501 control module 300 can obtain the tightening torque, loosening torque, thread torque, and torque under the head.

[0064] For S502, after confirming the tightening torque, loosening torque, and bolt specification parameters, the total friction coefficient can be obtained based on the first calculation model. This first calculation model can be configured in the control module 300 and conforms to the following formula: in, The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; This refers to the anti-loosening torque. Bolt specifications include pitch, thread pitch diameter, and head friction diameter; thread specifications can be measured.

[0065] For S503, given the total friction coefficient, and combining the obtained thread torque, tightening torque, and bolt specifications, the thread friction coefficient can be obtained based on the second calculation model. This second calculation model can be configured in the control module 300 and conforms to the following formula: in, The coefficient of friction of the thread; The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; This refers to the thread torque.

[0066] For S504, given the total friction coefficient, and combining the obtained head torque, tightening torque, and thread specification parameters, the head friction coefficient can be obtained based on the third calculation model. This third calculation model can be configured in the control module 300 and conforms to the following formula: in, The coefficient of friction under the head; The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; This refers to the torque at the top.

[0067] As can be seen from the above, Additionally, it should be noted that S503 and S504 do not have a specific order; they can be executed simultaneously. Furthermore, this bolt friction test method can be configured in the control module 300, and correspondingly, the first calculation model, the second calculation model, and the third calculation model are all deployed in the control module 300.

[0068] The bolt friction testing method provided in this application is configured in the control module 300 of the bolt friction testing system. It eliminates the need for additional clamping force parameter acquisition; it can acquire only the tightening torque, loosening torque, thread torque, and head torque. Combined with thread specification parameters, and based on the first, second, and third calculation models, it yields the total friction coefficient, thread friction coefficient, and head friction coefficient. Furthermore, the tooling in this bolt friction testing system can eliminate the clamping force detection component, reducing axial space occupation and enabling it to adapt to friction testing of shorter bolts.

[0069] In other words, the technical solution provided in this application, under the premise that the clamping force detection function component of the bolt friction testing fixture is eliminated, and the bolt friction testing method provided in this application is deployed in a system with the bolt friction testing fixture, can still achieve the same function of testing the friction coefficient as the existing horizontal bolt friction testing machine, and can be further adapted to the friction coefficient testing of short bolts.

[0070] It should be noted that the control module 300 mentioned in this application can be a module with control functions composed of a host computer and a slave device. The host computer and the slave device are connected for communication. The host computer can be, for example, an industrial control computer or a tablet computer, and can be equipped with a human-machine interface and a first calculation model, a second calculation model, and a third calculation model. Through the human-machine interface, there are buttons for starting and stopping the torque application shaft 200, inputting the required torque, bolt specification parameters, etc., and outputting corresponding torque parameters, friction coefficient parameters, etc. The slave device can be, for example, a programmable logic controller (PLC), a microcontroller, or a microprocessor, and is directly connected for communication with the torque application shaft 200 and the torque acquisition module 12 to realize real-time control response and data acquisition.

[0071] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A bolt friction testing fixture, characterized in that, include: The support plate assembly (11) is provided with a first through hole (H1) extending axially. A torque acquisition module (12) is axially spaced on one side of the support plate assembly (11), and the axial end of the torque acquisition module (12) near the support plate assembly (11) is a torque input end (121); and, The threaded insert (13) has a second through hole (H2) extending axially and includes an embedded end and an exposed end; The embedded end is inserted into the first through hole (H1), and the portion of the second through hole (H2) at the embedded end is a threaded hole section (H21), which is threaded to a bolt (400); the exposed end is located outside the first through hole (H1) and connected to the torque input end (121), and at least a portion of the exposed end can abut against the support plate assembly (11).

2. The bolt friction testing fixture according to claim 1, characterized in that, The first through hole (H1) includes a first hole segment (H11) and a second hole segment (H12), wherein the diameter of the first hole segment (H11) is smaller than the diameter of the second hole segment (H12); The first hole segment (H11) is farther away from the torque acquisition module (12) relative to the second hole segment (H12), and an annular surface (101) is formed at the junction of the first hole segment (H11) and the second hole segment (H12). When the exposed end abuts against the support plate assembly (11), there is an axial gap (G) between the end face of the embedded end and the annular surface (101).

3. The bolt friction testing fixture according to claim 1 or 2, characterized in that, The support plate assembly (11) includes a support plate (111) and a gasket (112), both of which are provided with through holes; The gasket (112) is stacked on the surface of the support plate (111) on the side away from the torque acquisition module (12), and the through hole of the gasket (112) is connected to the through hole of the support plate (111) to form the first through hole (H1).

4. The bolt friction testing fixture according to claim 3, characterized in that, The through hole of the gasket (112) is a stepped hole and the inner peripheral wall is formed with an annular surface (101) facing the end face of the embedded end, and the portion of the stepped hole located on the annular surface (101) away from the axial side of the embedded end is the first hole segment (H11).

5. The bolt friction testing fixture according to claim 1, characterized in that, The exposed end is provided with an ear plate (131), which can abut against the support plate assembly (11).

6. The bolt friction testing fixture according to claim 1, characterized in that, The portion of the second through hole (H2) at the exposed end position is a polygonal hole segment (H22), and the torque input end (121) is a polygonal column and is embedded in the polygonal hole segment (H22) in a shape-fitting manner.

7. A bolt friction testing system, characterized in that, It includes a torque application shaft (200), a control module (300), and a bolt friction test fixture (100) according to any one of claims 1 to 6. A bolt (400) is inserted into the first through hole (H1) and connected to the embedded end, and the torque applying shaft (200) is used to apply a total torque to the bolt (400); The control module (300) connects the torque acquisition module (12) and the torque application shaft (200) to obtain the thread torque and the total torque, and calculates the total friction coefficient, thread friction coefficient and head friction coefficient based on the thread torque, the total torque and bolt specification parameters.

8. A method for testing bolt friction, characterized in that, The bolt friction test system according to claim 7 is used, and includes the following steps: The bolt (400) is screwed in first and then unscrewed to obtain tightening torque, loosening torque, thread torque and head torque, wherein the head torque is the difference between the tightening torque and the thread torque; The total friction coefficient is obtained based on the tightening torque, the loosening torque, the bolt specifications, and the first calculation model, wherein the bolt specifications include the pitch, the thread pitch diameter, and the head friction diameter. The thread friction coefficient is obtained based on the thread torque, the total friction coefficient, the tightening torque, the bolt specification parameters, and the second calculation model. The coefficient of friction under the head is obtained based on the torque under the head, the total coefficient of friction, the tightening torque, the bolt specifications, and the third calculation model.

9. The bolt friction test method according to claim 8, characterized in that, The first calculation model conforms to the formula: in, The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; This is the anti-loosening torque.

10. The bolt friction test method according to claim 8, characterized in that, The second calculation model conforms to the formula: in, The coefficient of friction of the thread; The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; For thread torque; The third calculation model conforms to the formula: in, The coefficient of friction under the head; The coefficient of friction is the total friction coefficient. Pitch; The thread pitch diameter; The diameter of the friction point under the head; For tightening torque; This refers to the torque at the top.

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