Method for checking torsion of fastening bolt in narrow space

Abstract

The invention discloses a method for checking torsion of a fastening bolt in a narrow space. The method comprises the following steps: step 1, obtaining the size and position of the space where a fastening nut is located; 2, determining the overall size of the U-shaped verification tool according to the obtained space size and position; 3, a U-shaped verification tool is manufactured, one end of the U-shaped verification tool is provided with a nut sleeve, the other end of the U-shaped verification tool is provided with a dowel bar matched with a ratchet head of the torque wrench, the inner hexagonal rod and the nut sleeve are coaxially arranged, and the axis of the dowel bar and the axis of the nut sleeve are both perpendicular to two vertical rods of the U-shaped verification tool; and 4, performing torque test and equivalence verification on the U-shaped verification tool, sleeving a dowel bar of the U-shaped verification tool on a ratchet head of a torque wrench after the test is qualified, and extending a nut sleeve into a narrow space to perform torque verification on the spring tube fastening nut.

Description

Technical Field

[0001] The present invention belongs to the field of torque verification of fastening bolts, and particularly relates to a method for verifying the torque of fastening bolts in a narrow space. Background Art

[0002] Fastening bolts are used to connect various components and are applied in many fields. However, in some equipment, fastening bolts are installed in some narrow spaces to connect components. For example, when fixing the pantograph spring cylinder on the top of a rail vehicle, the fastening bolt needs to be installed between the spring cylinder and the tripod of the suspension device. However, after the rail vehicle has run for a period of time, it is necessary to verify the torque of the fastening bolt of the pantograph spring cylinder. Since the space between the spring cylinder and the tripod of the suspension device is narrow (see Figure 1 、 Figure 2 ), it is not possible to directly use a torque wrench for verification, and there is a problem of difficult construction. The current method for verifying torque is as follows: First, disassemble the tripod on the upper part of the pantograph spring cylinder, and then two people cooperate. One person holds the pantograph spring cylinder, and the other person operates the torque wrench for verification. After verification, the tripod on the upper part of the pantograph spring cylinder is restored to its original state. This verification method increases the construction volume, consumes manpower, has low efficiency, and increases the quality hidden dangers and safety risks during the process of disassembling and assembling parts. Moreover, the number of rail vehicles in existence is extremely large, and each rail vehicle needs to perform the operation of applying torque. Summary of the Invention

[0003] In order to solve the technical problems existing in the prior art, the present invention discloses a method for verifying the torque of fastening bolts in a narrow space. This method can avoid obstacles for torque application, overcome the problem that torque cannot be directly applied in a narrow space, and theoretically analyze and experimentally verify the method for improving torque accuracy. Furthermore, it achieves the effects of improving operation efficiency and reducing construction hidden dangers.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] The present invention provides a method for verifying the torque of fastening bolts in a narrow space, which can be used for verifying the torque of fastening bolts in various narrow spaces. The specific steps are as follows:

[0006] Step 1. Obtain the size and position of the space where the fastening nut is located;

[0007] Step 2. Determine the overall size of the U-shaped verification tool according to the obtained space size and position;

[0008] Step 3. Manufacture a U-shaped verification tool. One end of the U-shaped verification tool is provided with a nut sleeve, and the other end is a transmission rod that cooperates with the ratchet head of the torque wrench. The transmission rod is coaxially arranged with the nut sleeve, and the axes of the transmission rod and the nut sleeve are both perpendicular to the two vertical rods of the U-shaped verification tool;

[0009] Step 4. Conduct torque test and equivalence verification on the U-shaped calibration tool. After passing the test, sleevethe force transmission rod of the U-shaped calibration tool on the ratchet head of the torque wrench, and insert the nut sleeve into the narrow space to perform torque calibration on the fastening nut of the spring cylinder.

[0010] As a further technical solution, the specific equivalence test method is as follows: Set different target torque values M for the fastening nuts on the spring cylinder. First, directly use the torque wrench to set the M torque value and apply torque, and then use the U-shaped calibration tool to verify the M torque value; then, first use the U-shaped calibration tool to set the M torque value and apply torque, and then use the torque wrench to verify the M torque value. If the verification results are exactly the same in the two different methods before and after, the equivalence is verified.

[0011] As a further technical solution, when determining the overall dimensions in Step 2, take the U-shaped calibration tool as the concentric axis, without resistance to the surroundings, with the shortest possible dimensions and being convenient to use as the principle.

[0012] As a further technical solution, the nut sleeve is welded to the end of the U-shaped calibration tool, and it is ensured that the nut sleeve is welded coaxially with the end of the U-shaped calibration tool.

[0013] As a further technical solution, the method of torque test in Step 4 is as follows: Set a target value, and then use a torque tester to perform torque tests on the torque when only using the torque wrench and when using the torque wrench plus the U-shaped calibration tool respectively, and determine whether there is a deviation.

[0014] As a further technical solution, the method of torque calibration for the fastening nut of the spring cylinder in Step 4 is as follows:

[0015] Set the torque value to be calibrated on the torque wrench, then rotate it. Sleevethe force transmission rod of the U-shaped calibration tool on the ratchet head of the torque wrench, insert the nut sleeve of the U-shaped calibration tool into the narrow space to the fastening nut of the spring cylinder, and then perform torque calibration. When the torque value of the torque wrench reaches the set value, the calibration is completed.

[0016] As a further technical solution, the body of the U-shaped calibration tool is formed by bending the force transmission rod.

[0017] As a further technical solution, the method for torque calibration of the fastening bolt in the narrow space is used to calibrate the fastening bolt of the pantograph spring cylinder of the rail vehicle;

[0018] As a further technical solution, when performing torque calibration on the fastening bolt of the pantograph spring cylinder of the rail vehicle,

[0019] Obtain the model number of the fastening nut between the spring cylinder and the tripod of the rail vehicle, and determine the dimensions of the nut sleeve and the force transmission rod in the U-shaped calibration tool;

[0020] Determine the overall dimensions of the U-shaped calibration tool according to the structures of the spring cylinder and the tripod and the position of the fastening nut.

[0021] As a further technical solution, in step 4, an equivalence verification method is used to test the U-shaped calibration tool, specifically as follows:

[0022] Remove the tripod at the bottom of the rail vehicle. First, use a torque wrench to check the torque of the fastening nut and record the verification result; then reinstall the tripod, and use the U-shaped calibration tool in cooperation with the torque wrench to check the torque of the fastening nut again, record the verification result, and judge the deviation between the two.

[0023] The beneficial effects of the present invention are as follows:

[0024] By designing the U-shaped calibration tool, torque testing and equivalence verification are carried out on the U-shaped calibration tool. After passing the test, the force transmission rod of the U-shaped calibration tool is sleeved on the ratchet head of the torque wrench, and the nut sleeve extends into the narrow space to check the torque of the fastening nut of the spring cylinder; this makes the calibration method simple. The original calibration that required the disassembly of some components can now be directly carried out, making the construction process simple and easy; it saves manpower. Originally, when checking the torque, two people were required to cooperate, but now with the help of the U-shaped calibration tool, only one person is needed to complete this process, and it is convenient to use; it reduces potential quality hazards, avoids the process of disassembling and assembling parts, and reduces the probability of construction quality problems. Description of the Drawings

[0025] Figure 1 is a schematic diagram of the overall structure of the pantograph on the top of the rail vehicle;

[0026] Figure 2 is Figure 1 a schematic diagram of the installation positions of the spring cylinder and the tripod in

[0027] Figure 3 is a flowchart of the method for checking the torque of the fastening bolts of the pantograph spring cylinder of the rail vehicle proposed by the present invention;

[0028] Figure 4 is a three-dimensional schematic diagram of the U-shaped calibration tool used in the maintenance process of the present invention;

[0029] Figure 5 is a three-dimensional schematic diagram of the U-shaped calibration tool used in the maintenance process of the present invention;

[0030] Figure 6 is a two-dimensional structure schematic diagram of the U-shaped calibration tool used in the maintenance process of the present invention;

[0031] In the figure: 1. tripod, 2. fastening bolt, 3. spring cylinder, 4. U-shaped calibration tool, 5. nut sleeve, 6. inner hexagon rod. Detailed implementation manners

[0032] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0033] It should be noted that the terms used herein are merely for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the present invention clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof;

[0034] For the convenience of description, if the words "upper", "lower", "left", and "right" appear in the present invention, they only indicate the same directions as the upper, lower, left, and right of the attached drawings themselves, and do not limit the structure. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0035] In order to solve the problem of the method for checking the torque of fastening bolts in a narrow space, the present invention proposes a method for checking the torque of fastening bolts in various narrow spaces, and the specific steps are as follows: Step 1. Obtain the size and position of the space where the fastening nut is located; Step 2. Determine the overall size of the U-shaped checking tool according to the obtained space size and position; Step 3. Manufacture the U-shaped checking tool, one end of the U-shaped checking tool is provided with a nut sleeve, and the other end is a force transmission rod that cooperates with the ratchet head of the torque wrench. The force transmission rod is coaxially arranged with the nut sleeve, and the axes of the force transmission rod and the nut sleeve are both perpendicular to the two vertical rods of the U-shaped checking tool; Step 4. Conduct torque testing and equivalence verification on the U-shaped checking tool. After passing the test, put the force transmission rod of the U-shaped checking tool on the ratchet head of the torque wrench, and the nut sleeve extends into the narrow space to check the torque of the spring cylinder fastening nut. By designing the U-shaped checking tool, conducting torque testing and equivalence verification on the U-shaped checking tool, after passing the test, putting the force transmission rod of the U-shaped checking tool on the ratchet head of the torque wrench, and the nut sleeve extends into the narrow space to check the torque of the spring cylinder fastening nut, the checking method becomes simple. The checking that originally required the disassembly of some components can now be directly carried out, and the construction process becomes simple and easy; it saves manpower. Originally, when checking the torque, two people were required to cooperate, but now with the help of the U-shaped checking tool, only one person can complete this process, and it is convenient to use; it reduces potential quality hazards, avoids the process of disassembling and assembling parts, and reduces the probability of construction quality problems occurring.

[0036] There is no clear requirement for the space size of the "narrow space" in the present invention. As long as the surrounding space is inconvenient to operate during the operation of checking the torque of the fastening bolt, the method provided by the present invention can be adopted.

[0037] Furthermore, the checking method proposed in the present invention can be applied to bolts with various head shapes, such as hexagonal, circular, square, etc. This embodiment takes the bolt with a hexagonal head as an example for illustration; when checking the torque of bolts with other head shapes, the shape of the nut sleeve can be changed.

[0038] Furthermore, the internal hexagonal rod in this embodiment is used as the force transmission rod, and its cross-sectional shape is determined according to the torque wrench that cooperates with it. This embodiment is only an illustration taking the internal hexagonal rod as an example.

[0039] This embodiment takes the torque checking of the fastening bolts of the spring cylinder of the pantograph on the top of the rail vehicle as an example to illustrate in detail the method for checking the torque of the fastening bolts in the narrow space proposed by the present invention:

[0040] The installation position of the fastening bolts of the spring cylinder of the pantograph on the top of the rail vehicle is as Figure 1 、 Figure 2 shown, from Figure 1 、Figure 2 It can be seen that the space between the spring cylinder 3 and the suspension device tripod 1 is narrow, and it is impossible to directly calibrate the fastening bolt 2 with a torque wrench. Therefore, the existing method for calibrating the torque is as follows: First, disassemble the tripod 1, and then two people cooperate. One person holds the spring cylinder 3, and the other person operates the torque wrench to calibrate the fastening bolt 2. After calibration, the tripod 1 is reinstalled on the spring cylinder 3 to restore the original state. Obviously, this method increases the construction workload, consumes manpower, has low efficiency, and the process of disassembling and assembling parts increases the quality hidden dangers and safety risks. The number of rail vehicles in service is extremely large, and torque application operations need to be carried out for each rail vehicle. This embodiment provides a method for calibrating the torque of fastening bolts in a narrow space, which can be exactly used for calibrating the torque of the fastening bolts of the spring cylinder of the pantograph on the top of the rail vehicle.

[0041] Specifically, in a typical implementation manner of the present invention, the method for calibrating the torque of the fastening bolts of the pantograph spring cylinder of the rail vehicle is as Figure 3 shown, and includes the following steps:

[0042] Step 1: Obtain the model of the fastening nut between the spring cylinder and the tripod of the rail vehicle, and determine the dimensions at both ends of the U-shaped calibration tool;

[0043] Step 2: According to the structures of the spring cylinder and the tripod and the position of the fastening nut, with the U-shaped calibration tool as the concentric axis, determine the distance between both ends of the U-shaped calibration tool;

[0044] Step 3: Manufacture the U-shaped calibration tool. One end of the U-shaped calibration tool is a nut sleeve, and the other end is an internal hexagonal rod that cooperates with the ratchet head of the torque wrench. The internal hexagonal rod is coaxially arranged with the nut sleeve, and the axes of the internal hexagonal rod and the nut sleeve are both perpendicular to the two vertical rods of the U-shaped calibration tool;

[0045] Step 4: Conduct torque testing and equivalence verification on the U-shaped calibration tool. After the testing and equivalence verification are qualified, sleeved the internal hexagonal rod of the U-shaped calibration tool on the ratchet head of the torque wrench, and insert the nut sleeve into the narrow space to calibrate the torque of the fastening nut of the spring cylinder.

[0046] As a further technical solution, in the step 4, an equivalent testing method is adopted to test the U-shaped calibration tool, which is specifically as follows:

[0047] Remove the tripod at the bottom of the rail vehicle, first calibrate the torque of the fastening nut with a torque wrench, and record the calibration result; then reinstall the tripod, and use the U-shaped calibration tool in cooperation with the torque wrench to calibrate the torque of the fastening nut again, record the calibration result, and judge the deviation between the two.

[0048] As a further technical solution, the specific method is as follows: Set different target torque values M for the fastening nuts on the spring cylinder. First, directly use a torque wrench to set the M torque value and apply torque, and then use a U-shaped calibration tool to calibrate the M torque value. After that, first use the U-shaped calibration tool to set the M torque value and apply torque, and then use a torque wrench to calibrate the M torque value. If the verification results of the two different methods before and after are exactly the same, the equivalence is verified.

[0049] As a further technical solution, when determining the overall dimensions of the U-shaped calibration tool in step 2, the principle is that the inner hexagonal rod and the nut sleeve of the U-shaped calibration tool are concentric axes, the U-shaped calibration tool does not resist against the surroundings, and the size of the U-shaped calibration tool is as short as possible.

[0050] As a further technical solution, the nut sleeve is welded to the end of the U-shaped calibration tool, and it is ensured that the nut sleeve and the end of the U-shaped calibration tool are coaxially welded.

[0051] As a further technical solution, the method of torque testing in step 4 is as follows: Set a target value, and then use a torque tester to test the torque when only using a torque wrench and when using a torque wrench plus a U-shaped calibration tool respectively, and determine whether there is a deviation.

[0052] As a further technical solution, the method of torque calibration for the fastening nut of the spring cylinder in step 4 is as follows:

[0053] Set the torque value to be calibrated on the torque wrench, and then rotate it. Put the inner hexagonal rod of the U-shaped calibration tool on the ratchet head of the torque wrench, and insert the nut sleeve of the U-shaped calibration tool into the narrow space to the fastening nut of the spring cylinder, and then perform torque calibration. When the torque value of the torque wrench reaches the set value, the calibration is completed.

[0054] In this embodiment, by analyzing the relationships among torque, shear force, torsional section modulus, and torque borne by the transmission shaft in material mechanics, the influencing factors of strain and torque at both ends of the transmission shaft are deduced; a concentric-axis U-shaped calibration tool is proposed and optimized and verified through comparative tests, solving various problems: (1) Difficult construction and large construction volume. Due to the narrow space in the construction area, the torque wrench cannot be directly put in, resulting in difficult construction and reduced work efficiency; (2) Labor-consuming. It is necessary to disassemble the nearby components before applying torque, and multiple people are required to cooperate; (3) There are greater potential quality hazards. Increasing the process of disassembling and assembling parts increases the probability of construction quality problems; (4) It can be applied to other scenarios where direct application is not possible. The present invention can greatly improve the torque application efficiency and save construction costs.

[0055] The following combines the relevant drawings, and the specific method steps of the method for calibrating the torque of the fastening bolt of the pantograph spring cylinder proposed in this embodiment are as follows:

[0056] First: The core problem that makes the spring barrel torque calibration process difficult is that the space between the spring barrel and the tripod is small, and the torque wrench cannot be used directly. The basic idea of ​​the optimization plan is to put one end of the U-shaped calibration tool on the ratchet head of the torque wrench during construction, and the other end can be directly extended into the narrow space to perform torque calibration on the spring barrel fastening nut. The theoretical basis for the design of this U-shaped calibration tool is that the torque values ​​at both ends of the tool must be equal or very similar. Only in this way, when one end of the U-shaped calibration tool is put on the ratchet head of the torque wrench to apply torque, the torque borne by the other end to calibrate the spring barrel fastening nut can be basically equivalent.

[0057] According to the torque calculation formula of material mechanics:

[0058] M=τ·W (1)

[0059] Where M is the torque borne by the transmission shaft; is the shear force borne by the transmission shaft; and W is the torsional section coefficient.

[0060] Regarding the torsional section coefficient W, we have:

[0061]

[0062] Where D is the diameter of the transmission shaft. Then:

[0063] M=0.2τ·D 3 (3)

[0064] The diameter D of the concentric shaft or transmission shaft is the same. Deflection is generally the linear displacement of the rod axis in the direction perpendicular to the axis when subjected to force. According to Hooke's law, the shear force is:

[0065]

[0066] According to formula (3) and formula (4), we have:

[0067]

[0068] Where E is the elastic modulus of the drive shaft material; μ is the Poisson's ratio of the drive shaft material; and ε is the strain of the drive shaft. Due to the influence of the deflection of the drive shaft, the strain of the end of the drive shaft that is indirectly stressed is smaller than that of the end of the shaft that is directly stressed. The shorter the drive shaft and the stronger the stiffness, the smaller the difference in strain ε at both ends. According to formula (5), on the basis of the same diameter D at both ends of the drive shaft (i.e., concentric shafts), the strain ε and the torque M are linearly related. The smaller the difference in strain ε at both ends of the drive shaft, the smaller the difference in torque actually borne by the two ends of the drive shaft.

[0069] Therefore, in theory, the U-shaped calibration tool must be concentric with the shaft, and the shorter the size and the stronger the rigidity, the smaller the difference in actual torque values ​​at both ends of the tool.

[0070] Second: Design and manufacture the U-shaped calibration tool used in the testing process below;

[0071] Basic information collection: The fastening nut 2 between the spring cylinder 3 and the tripod 1 is M8. The nut sleeve 5 at one end of the U-shaped calibration tool should be M13, and an M8 ratchet head is used at one end of the torque wrench.

[0072] Sketch drawing: Based on the structures of the spring cylinder 3 and the tripod 1 and the position of the M8 fastening nut 2, with the tool as the concentric axis, not conflicting with the surroundings, the dimensions being as short as possible, and being convenient for use as the principles. Sketch the general outline of the tool.

[0073] Measure the dimensions: According to the outline of the U-shaped calibration tool in the sketch, measure the dimensions of each part with a scale. Design two U-shaped calibration tools with different dimensions, the lengths of the inner hexagon rods being 240 mm and 180 mm respectively, for comparative experiments;

[0074] 3D modeling: According to the design requirements, establish a 3D model of the U-shaped calibration tool using SolidWorks.

[0075] Draw 2D drawings: Draw engineering 2D drawings from the 3D model. Take the U-shaped calibration tool with an inner hexagon rod length of 180 mm as an example, as Figure 4 shown.

[0076] Material selection: Select M8 inner hexagon rods with lengths of 240 mm and 180 mm and sleeve heads of M13, and all use chromium vanadium steel materials with relatively high stiffness.

[0077] Prototype production: After material selection, process and produce prototypes according to the drawings through welding technology; Bend the M8 inner hexagon rods with lengths of 240 mm and 180 mm into a U shape respectively or cut them and weld them into a U shape. One end of the U-shaped calibration tool extends horizontally by a certain distance, and the nut sleeve 5 is welded to the other end; and ensure that the nut sleeve 5 is coaxially arranged with the extended inner hexagon rod 6 of the U-shaped calibration tool.

[0078] Third, after the above tools are manufactured, torque testing and deviation calculation are required,

[0079] Torque testing: Use a torque tester to conduct torque testing on using only the torque wrench and after adding two U-shaped calibration tools with different dimensions respectively. Take the set target value of 18 N·m as an example for testing; The torque tester displays the test results;

[0080] Record the displayed values and calculate the deviation values according to the deviation calculation formula (6).

[0081]

[0082] The torque test results and deviation calculation are shown in Table 1:

[0083]

[0084]

[0085] Three conclusions can be drawn from Table 1 above:

[0086] (1) The measurement deviations when only using a torque wrench and when adding a U-shaped calibration tool are both no more than 4%, meeting the accuracy requirements.

[0087] (2) The measurement deviation becomes larger after adding the U-shaped calibration tool compared to only using the torque wrench, indicating that the deflection of the U-shaped calibration tool does cause torque differences at both ends and increases the error.

[0088] (3) The U-shaped calibration tool with a smaller size has a smaller measurement deviation than the one with a larger size, reducing the error caused by deflection and having a higher measurement accuracy.

[0089] The experimental results also prove the correctness of the theoretical analysis of the concentric axis and deflection.

[0090] Fourth, Equivalence Verification and Optimization Effect

[0091] The meaning of equivalence is that after removing the tripod 1, the effect of only using a torque wrench to calibrate the torque is the same as that of using a U-shaped calibration tool for torque calibration. According to theoretical analysis, actual torque tests and deviation calculations, a U-shaped calibration tool with a smaller size and higher precision is selected for equivalence verification.

[0092] The method of equivalence verification is to set target torque values M for the M8 fastening nuts on the spring cylinder respectively, where M ∈ {10 N·m, 12 N·m, 14 N·m, 16 N·m, 18 N·m}. First, directly use the torque wrench to set the M torque value and apply torque, and then use the U-shaped calibration tool to verify the M torque value. After that, first use the U-shaped calibration tool to set the M torque value and apply torque, and then use the torque wrench to verify the M torque value. The verification result shows that for the two different methods before and after, the verification results are exactly the same, and the equivalence is verified.

[0093] Fifth, the verified U-shaped calibration tool can be used to calibrate the fastening bolts of the pantograph spring cylinder of other rail vehicles. The specific calibration method is as follows:

[0094] Set the torque value to be calibrated on the torque wrench. Put the hexagon bar of the U-shaped calibration tool on the ratchet head of the torque wrench. Use the U-shaped calibration tool to avoid resistance from the surroundings, insert the nut sleeve of the U-shaped calibration tool into the narrow space to the fastening nut of the spring cylinder for torque calibration. When hearing a "click" sound, the calibration is completed.

[0095] It should be further noted that this tool can be used not only for the verification of bolts, but also for the pre-tightening of bolts themselves in other narrow spaces.

[0096] The method for verifying the torque of the fastening bolts of the pantograph spring cylinder of the rail vehicle proposed in this embodiment uses a U-shaped verification tool with a deviation value meeting the accuracy requirements and having torque verification equivalence. Based on these important results, the optimization effect of the torque verification process in actual construction is as follows: the construction becomes simple. The original construction process of removing the tripod and then verifying the fastening bolts of the spring cylinder becomes simple and easy; it saves manpower. Originally, when verifying the torque, two people were required to cooperate. Now, with the help of the U-shaped verification tool, only one person can complete this process, and it is convenient to use; it reduces potential quality hazards, avoids the process of disassembling and assembling parts, and reduces the probability of construction quality problems.

[0097] This embodiment uses material mechanics torque, shear force, torsional section modulus, Hooke's law, etc. to deduce the influencing factors of strain at both ends of the transmission shaft and the torque relationship, and proposes a concentric shaft U-shaped verification tool. It can avoid obstacles to torque application, overcome the problem of being unable to directly apply torque in a narrow space, and theoretically analyze and experimentally verify the method to improve torque accuracy. Furthermore, it achieves the effects of improving work efficiency and reducing construction hazards.

[0098] Furthermore, the rail vehicle described in this embodiment can be any suitable type of vehicle, such as a regular-speed train, a bullet train, etc. This embodiment is not limited to a certain or certain specific types of rail vehicles.

[0099] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for checking the torque of a fastening bolt in a narrow space, characterized in that: as follows: Step 1. Obtain the size and position of the space where the fastening nut is located; Step 2. Determine the overall size of the U-shaped calibration tool according to the obtained space size and position; Step 3. Make a U-shaped calibration tool, wherein a nut sleeve is provided at one end of the U-shaped calibration tool, and a force transmission rod matched with the ratchet head of the torque wrench is provided at the other end, wherein the force transmission rod and the nut sleeve are coaxially arranged, and the axes of the force transmission rod and the nut sleeve are perpendicular to the two vertical rods of the U-shaped calibration tool; Step 4. Perform torque test and equivalence verification on the U-type calibration tool. After passing the test, put the force transmission rod of the U-type calibration tool on the ratchet head of the torque wrench, and extend the nut sleeve into the narrow space to perform torque calibration on the spring tube fastening nut.

2. The method for checking the torque of a fastening bolt in a narrow space according to claim 1, characterized in that: The specific equivalent test method is: set different target torque values ​​M for the fastening nuts on the spring tube, first use the torque wrench to set the M torque value and apply torque, and then use the U-shaped verification tool to verify the M torque value; then, use the U-shaped verification tool to set the M torque value and apply torque, and then use the torque wrench to verify the M torque value; if the verification results of the two different methods are completely consistent, the equivalence is verified.

3. The method for checking the torque of a fastening bolt in a narrow space according to claim 1, characterized in that: When determining the overall size of the U-shaped calibration tool in step 2, the principle is that the force transmission rod and the nut sleeve of the U-shaped calibration tool are coaxial axes, the U-shaped calibration tool does not resist the surroundings, and the size of the U-shaped calibration tool is as short as possible.

4. The method for checking the torque of a fastening bolt in a narrow space according to claim 1, characterized in that: The nut sleeve is welded to the end of the U-shaped calibration tool, and it is ensured that the nut sleeve and the end of the U-shaped calibration tool are coaxially welded.

5. The method for checking the torque of a fastening bolt in a narrow space according to claim 1, characterized in that: The method for performing torque testing on the U-shaped calibration tool in step 4 is as follows: a target value is set, and then a torque tester is used to perform torque testing on the torque when only a torque wrench is used and the torque wrench plus the U-shaped calibration tool is used to determine whether there is a deviation.

6. The method for checking the torque of a fastening bolt in a narrow space according to claim 1, characterized in that: The method for checking the torque of the spring tube fastening nut in step 4 is as follows: Set the torque value to be checked on the torque wrench, then rotate it, put the force transmission rod of the U-shaped verification tool on the ratchet head of the torque wrench, extend the nut sleeve of the U-shaped verification tool into the narrow space to tighten the nut on the spring tube, and then perform torque verification. When the torque value of the torque wrench reaches the set value, the verification is completed.

7. The method for checking the torque of a fastening bolt in a narrow space according to claim 1, characterized in that: The body of the U-shaped calibration tool is formed by bending a force transmission rod.

8. The method for checking the torque of a fastening bolt in a narrow space according to claim 1, characterized in that: The method for checking the torque of fastening bolts in a narrow space is used to check the fastening bolts of the pantograph spring cylinder of a rail vehicle.

9. The method for checking the torque of a fastening bolt in a narrow space according to claim 8, characterized in that: When checking the torque of the pantograph spring barrel fastening bolts on rail vehicles, Obtain the model of the fastening nut between the spring cylinder and the tripod of the rail vehicle, and determine the size of the nut sleeve and the force transmission rod in the U-shaped calibration tool; The overall size of the U-shaped calibration tool is determined according to the spring tube, tripod structure, and the position of the fastening nut.

10. The method for checking the torque of a fastening bolt in a narrow space according to claim 9, characterized in that: In step 4, the U-type calibration tool is tested by using an equivalence verification method, as follows: Remove the tripod at the bottom of the rail vehicle, first use a torque wrench to check the torque of the fastening nuts, and record the verification results; then install the tripod, use a U-shaped verification tool and a torque wrench to check the torque of the fastening nuts again, record the verification results, and determine the deviation between the two.

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