Tightening process development method, device and system suitable for bolt group

Abstract

The invention discloses a tightening process development method, device and system suitable for a bolt group, and the method comprises the steps: calculating the pre-tightening force range of a bolt based on the material performances of the bolt and a connected part; taking the constraint condition that the final pre-tightening force obtained by each bolt in the bolt group under the action of the tightening torque corresponding to the initial pre-tightening force is within the pre-tightening force range, and continuously iterating the elastic interaction matrix according to the relationship among the target final pre-tightening force matrix, the elastic interaction matrix and the initial pre-tightening force matrix to obtain a final pre-tightening force matrix; and correcting the initial pre-tightening force of each bolt in the initial pre-tightening force matrix to obtain the final initial pre-tightening force of each bolt. According to the invention, the consistency of the connection pretightening force of each bolt in the bolt group can be ensured, and the bolt connection quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of bolt tightening process design technology, specifically relating to a method, device and system for developing tightening processes for bolt groups. Background Technology

[0002] Bolted connections are widely used in the main body and core components of construction machinery, and the consistency of their assembly performance has a significant impact on the reliability of the main body and core components. Tightening process parameters are an important means of ensuring the quality of bolted connections. Currently, in the construction machinery industry, bolt tightening torques are mainly based on national or industry standards, and tightening sequences are determined by experience. This can easily lead to problems such as unstable bolt group connection quality (breakage, loosening), affecting the reliability of the entire machine and core components. The development and verification of bolt group tightening processes are of great significance for improving the design and reliability of bolt group connections.

[0003] Chinese invention patent application No. 202411630101.7 discloses a test device for the correlation between multi-bolt tightening sequence and fit. This device can study and measure the changes in preload of other bolts caused by various tightening conditions of different bolts, so as to accurately control the preload. However, it lacks a preload design method and does not provide how to optimize the effect of different tightening sequences on the preload.

[0004] Chinese invention patent application No. 202210332701.X discloses a method for assembling bolt assemblies. This method selects a pre-tightening strategy in each pre-tightening operation by using elastic interaction matrices corresponding to different strategies, optimizing the pre-tightening force applied to each bolt at each step, and finally providing the optimal pre-tightening method under the conditions of satisfying the strength constraints of the connecting parts and the bolt strength. This method requires providing elastic interaction matrices (at least two) under different pre-tightening strategies, and obtaining the optimal pre-tightening method through an optimization model. The accuracy of the model depends on the number and quality of the pre-tightening strategies, which has certain limitations. Furthermore, it requires extensive preliminary experimental preparation and the optimization process is relatively complex.

[0005] Chinese invention patent application No. 202410285830.7 discloses a method, device, system, and medium for optimizing bolt tightening process. This scheme, through theory, calculation, and testing, takes the minimum current yield clamping force and adjusts it according to a preset proportional coefficient and torque tolerance to ensure the reliability of bolt tightening. However, this invention does not consider the material properties of the connected parts or the bolt yielding caused by the tightening torque, and it does not provide a control range for the torque coefficient that directly affects the mapping relationship between preload and torque. It only adjusts based on a pre-given tolerance, which can easily lead to instability during implementation.

[0006] In summary, existing publicly available solutions mainly focus on one part of the bolt assembly tightening process development process, without comprehensively considering the control of the entire process. The optimization methods are relatively complex and have many limitations. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a method, apparatus, and system for developing a tightening process for bolt groups, which can ensure the consistency of the preload of each bolt in the bolt group and improve the quality of the bolt connection.

[0008] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0009] In a first aspect, the present invention provides a method for developing a tightening process suitable for bolt assemblies, comprising:

[0010] Based on the material properties of the bolt and the connected parts, the preload range of the bolt is calculated;

[0011] The constraint is that the final preload of each bolt in the bolt group is within the preload range under the tightening torque corresponding to the initial preload. Based on the relationship between the target final preload matrix, the elastic interaction matrix and the initial preload matrix, the elastic interaction matrix is ​​continuously iterated, and the initial preload of each bolt in the initial preload matrix is ​​corrected to obtain the final initial preload of each bolt.

[0012] In conjunction with the first aspect, optionally, the method for calculating the preload range of the bolt includes:

[0013] Based on the material properties of the bolt and the connected parts, the critical load at which the bolt yields when tightened using the torque method, and the maximum load at which the surface of the contact area between the bolt and the connected parts does not crush are calculated.

[0014] With the goal of ensuring that neither the bolt nor the connected object yields or crushes, the maximum allowable preload during the bolt connection process is calculated based on the critical load and the maximum load.

[0015] Based on the maximum preload and the preset safety factor, the preload range of the bolt is calculated.

[0016] In conjunction with the first aspect, optionally, the formula for calculating the critical load at which the bolt yields when tightened using the torque method is as follows:

[0017] ,

[0018] In the formula, This refers to the critical load at which the bolt yields when tightened using the torque method. This refers to the bolt yield stress. The cross-sectional area of ​​the thread stress is... The cross-sectional area of ​​the thread stress The diameter of the corresponding equivalent circular cross section, For pitch, The coefficient of friction of the thread. The thread pitch diameter;

[0019] The formula for calculating the maximum load that prevents crushing of the surface of the contact area between the bolt and the connected component is as follows:

[0020] ,

[0021] In the formula, The maximum load that prevents crushing of the surface of the connected parts and the bolt contact area. This is the surface compressive stress limit, which is the minimum stress required for the surface of the contact area between the bolt and the connected parts to crush. The outer diameter of the effective contact area between the bolt and the connected parts. The inner diameter of the effective contact area between the bolt and the connected parts;

[0022] The formula for calculating the maximum allowable preload force during the bolt connection process is as follows:

[0023] ,

[0024] In the formula, This refers to the maximum preload force that can be applied during bolted connections.

[0025] The formula for calculating the preload range of the bolt is:

[0026] ,

[0027] In the formula, This refers to the preload range of the bolt. For safety margin, the value is set between 65% and 80%.

[0028] In conjunction with the first aspect, optionally, the mathematical expression for the relationship between the target final preload matrix, the elastic interaction matrix, and the initial preload matrix is:

[0029] ,

[0030] In the formula, The target final preload matrix, The initial preload matrix, For bolts The initial preload, For bolts The target final preload, This represents the total number of bolts. For a flexible interaction matrix, matrix elements The calculation formula is:

[0031] ,

[0032] In the formula, The final preload matrix is ​​formed by the final preload of all bolts in the bolt group;

[0033] Repeat the following steps until all the final preloads in the last column of the final preload matrix are within the preload range:

[0034] When the final preload matrix If the last column contains a final preload outside the preload range, then the initial preload of each bolt is corrected according to the relationship between the target final preload matrix, the elastic interaction matrix, and the initial preload matrix.

[0035] Based on the corrected initial preload of each bolt, calculate the new tightening torque of each bolt;

[0036] According to the predetermined tightening sequence, each bolt in the bolt group is tightened in turn according to the new tightening torque of each bolt. After each bolt is tightened, the final preload of the tightened bolts is obtained as a column of data in the final preload matrix. This process continues until all bolts are tightened, forming a new final preload matrix.

[0037] In conjunction with the first aspect, optionally, the formula for calculating the tightening torque is:

[0038] ,

[0039] In the formula, For tightening torque; This is the torque coefficient for bolted connections. For preload, This refers to the nominal diameter of the bolt.

[0040] In conjunction with the first aspect, optionally, the deviation ratio of the torque coefficient is ≤20%, and the formula for calculating the deviation ratio of the torque coefficient is: maximum torque coefficient - minimum torque coefficient / maximum torque coefficient.

[0041] In conjunction with the first aspect, the constraints may optionally include:

[0042] The final tightening torque of each bolt is less than its corresponding yield torque.

[0043] In conjunction with the first aspect, optionally, the method for calculating the yield torque includes:

[0044] Calculate the rate of change of the slope of the tightening curve. The formula for calculating the rate of change of the slope of the tightening curve is:

[0045] ,

[0046] In the formula, To determine the rate of change of the slope of the tightening curve. For the first One tightening torque For the first One tightening torque For the first One tightening torque, For the first Tighten at an angle. For the first Tighten at an angle. For the first One tightening angle;

[0047] When the rate of change of the slope of the tightening curve exceeds the set threshold, the tightening torque corresponding to the rate of change of the slope of the tightening curve is the yield torque.

[0048] Secondly, the present invention provides an apparatus for developing a tightening process for bolt assemblies, comprising:

[0049] Preload testing equipment is used to obtain the final preload of each bolt;

[0050] The controller, connected to the preload detection device, is configured to perform the method described in any one of the first aspects.

[0051] Thirdly, the present invention provides a tightening process development system for bolt groups, including a storage medium and a processor;

[0052] The storage medium is used to store instructions;

[0053] The processor is configured to operate according to the instructions to perform the method described in any one of the first aspects.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] This invention proposes a method, apparatus, and system for developing a tightening process for bolt groups. An elastic interaction matrix is ​​constructed based on the tightening sequence. Using the constraint that the final preload of each bolt in the bolt group is within the preload range, and combined with the target final preload matrix, the initial preload of each bolt is optimized to obtain the final initial preload of each bolt. This ensures the consistency of the preload of each bolt connection in the bolt group and improves the quality of the bolt connection. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0057] Figure 1 This is a flowchart illustrating a method for developing a tightening process for bolt assemblies according to an embodiment of the present invention.

[0058] Figure 2 This is a schematic diagram illustrating the principle of yield torque calculation in one embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of the initial preload optimization process according to an embodiment of the present invention;

[0060] Figure 4 This is a structural diagram of a fan-shaped sample according to an embodiment of the present invention. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0062] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0063] Example 1

[0064] This invention provides a method for developing a tightening process for bolt assemblies, such as... Figure 1 As shown, it includes the following steps:

[0065] (1) Calculate the preload range of the bolt based on the material properties of the bolt and the connected parts;

[0066] (2) Taking the constraint that the final preload of each bolt in the bolt group is within the preload range under the tightening torque corresponding to the initial preload, the elastic interaction matrix is ​​continuously iterated according to the relationship between the target final preload matrix, the elastic interaction matrix and the initial preload matrix, and the initial preload of each bolt in the initial preload matrix is ​​corrected to obtain the final initial preload of each bolt.

[0067] In the above scheme, an elastic interaction matrix is ​​constructed according to the tightening sequence. The constraint condition is that the final preload of each bolt in the bolt group is within the preload range under the tightening torque corresponding to the initial preload. Combined with the target final preload matrix, the initial preload of each bolt is optimized to obtain the final initial preload of each bolt. This can ensure the consistency of the preload of each bolt connection in the bolt group and improve the bolt connection quality.

[0068] In one specific embodiment of the present invention, the method for calculating the preload range of the bolt includes:

[0069] Based on the material properties of the bolt and the connected parts, the critical load at which the bolt yields when tightened using the torque method, and the maximum load at which the surface of the contact area between the bolt and the connected parts does not crush are calculated.

[0070] With the goal of ensuring that neither the bolt nor the connected object yields or crushes, the maximum allowable preload during the bolt connection process is calculated based on the critical load and the maximum load.

[0071] Based on the maximum preload and the preset safety factor, the preload range of the bolt is calculated.

[0072] In one specific embodiment of the present invention, the calculation formula for the critical load at which the bolt yields when tightening the bolt using the torque method is as follows:

[0073] ,

[0074] In the formula, This refers to the critical load at which the bolt yields when tightened using the torque method. For the bolt yield stress, The cross-sectional area of ​​the thread stress is... The cross-sectional area of ​​the thread stress The diameter of the corresponding equivalent circular cross section, Pitch; The coefficient of friction of the thread. The thread pitch diameter;

[0075] The formula for calculating the maximum load that prevents crushing of the surface of the contact area between the bolt and the connected component is as follows:

[0076] ,

[0077] In the formula, The maximum load that prevents crushing of the surface of the connected parts and the bolt contact area. This is the surface compressive stress limit, which is the minimum stress required for the surface of the contact area between the bolt and the connected parts to crush. The outer diameter of the effective contact area between the bolt and the connected parts. The inner diameter of the effective contact area between the bolt and the connected parts;

[0078] To ensure the safety of the bolt and the connected parts, the maximum allowable preload force applied to the bolted connection should be sufficient to prevent both the bolt and the connected parts from yielding and crushing. Therefore, the formula for calculating the maximum allowable preload force during the bolted connection process is as follows:

[0079] ,

[0080] In the formula, This refers to the maximum preload force that can be applied during bolted connections.

[0081] The formula for calculating the preload range of the bolt is:

[0082] ,

[0083] In the formula, This refers to the preload range of the bolt. This is a safety factor. Due to the influence of the performance of the bolts and the connected parts, as well as the tightening tools, the actual preload on the bolted connection after tightening will fluctuate around the theoretical value. Therefore, to ensure the utilization rate of bolt performance and prevent overload, a safety factor is generally used. The preload should be 65% to 80%, meaning the preload should fall within the range of the following formula:

[0084] .

[0085] In one specific embodiment of the present invention, the mathematical expression relating the target final preload matrix, the elastic interaction matrix, and the initial preload matrix is ​​as follows:

[0086] ,

[0087] In the formula, The target final preload matrix, The initial preload matrix, For bolts The initial preload, For bolts The target final preload, This represents the total number of bolts. For a flexible interaction matrix, matrix elements The calculation formula is:

[0088] ,

[0089] In the formula, The final preload matrix is ​​formed by the final preload of all bolts in the bolt group;

[0090] Repeat the following steps until all the final preloads in the last column of the final preload matrix are within the preload range:

[0091] When the final preload matrix If the last column contains a final preload outside the preload range, then the initial preload of each bolt is corrected according to the relationship between the target final preload matrix, the elastic interaction matrix, and the initial preload matrix.

[0092] Based on the corrected initial preload of each bolt, calculate the new tightening torque of each bolt;

[0093] According to the predetermined tightening sequence, each bolt in the bolt group is tightened in turn according to the new tightening torque of each bolt. After each bolt is tightened, the final preload of the tightened bolts is obtained as a column of data in the final preload matrix. This process continues until all bolts are tightened, forming a new final preload matrix.

[0094] In one specific embodiment of the present invention, the formula for calculating the tightening torque is as follows:

[0095] ,

[0096] In the formula, For tightening torque; This is the torque coefficient for bolted connections. For preload, This refers to the nominal diameter of the bolt.

[0097] In one specific embodiment of the present invention, the torque coefficient deviation ratio range is ≤20%, and the calculation formula for the torque coefficient deviation ratio is: maximum torque coefficient - minimum torque coefficient / maximum torque coefficient. When the torque coefficient is large, the deviation range can be large, for example, the torque coefficient range is 0.20~0.25; when the torque coefficient is small, the deviation range needs to be smaller, for example, the torque coefficient range is 0.10~0.125.

[0098] In one specific embodiment of the present invention, the constraint conditions further include:

[0099] The final tightening torque of each bolt is less than its corresponding yield torque.

[0100] In one specific embodiment of the present invention, the method for calculating the yield torque includes:

[0101] The formula for calculating the rate of change of the slope of the tightening curve is as follows:

[0102] ,

[0103] In the formula, To determine the rate of change of the slope of the tightening curve. For the first One tightening torque, For the first One tightening torque, For the first One tightening torque, For the first Tighten at an angle. For the first Tighten at an angle. For the first One tightening angle;

[0104] When the rate of change of the tightening curve slope exceeds a set threshold, the tightening torque corresponding to this rate of change is the yield torque. In specific implementation, the threshold can be set to 50%, see details below. Figure 2 The number of tightening torque tests should be no less than 5 sets each time, and the minimum value should be taken as the yield torque of the bolt each time. In order to reduce the possibility of yielding, the tightening torque should generally not exceed 90% of the yield torque.

[0105] The following describes in detail the tightening process development method for bolt groups in an embodiment of the present invention, with reference to a specific implementation method.

[0106] Step 1: Design the preload range of the bolts based on the material properties of the bolts and the connected parts.

[0107] For bolted connections, the preload should not cause the bolts to yield. For bolted connections preloaded by controlling torque, the bolt threads are subjected to both tension and torsion during the preload stage. The critical load at which yielding occurs can be calculated and determined by formula (1).

[0108] (1),

[0109] In the formula, N is the critical load at which the bolt yields when tightened using the torque method; The bolt yield stress is given in MPa. The cross-sectional area of ​​the thread stress is mm2; The cross-sectional area of ​​the thread stress The corresponding equivalent circular cross-section diameter, mm; P is the pitch, mm; The coefficient of friction of the thread; The thread pitch diameter is in mm.

[0110] For bolted connections, the preload should not cause crushing of the surface of the contact area between the connected parts and the bolt (or nut / washer), resulting in a decrease in the anti-loosening ability of the bolt connection or damage to the connected parts. The maximum load that the surface of the contact area between the connected parts and the bolt (or nut / washer) can withstand can be calculated and determined by formula (2).

[0111] (2),

[0112] In the formula, The maximum load, in N, that prevents crushing of the contact area between the connected parts and the bolt (or nut / washer). The surface compressive stress limit is the minimum stress required for the material surface to crush, expressed in MPa. The outer diameter, in mm, of the effective contact area between the bolt (or nut / washer) and the connected parts; The inner diameter, in mm, of the effective contact area between the bolt (or nut / washer) and the connected part.

[0113] To ensure the safety of the bolt and the connected parts, the maximum allowable preload during the bolt connection process should be able to ensure that the bolt and the connected parts do not yield or crush at the same time, that is, it should meet the requirements of formula (3).

[0114] (3),

[0115] For bolted connections, the lower the preload, the smaller the ratio of the actual stress acting on the bolt cross-section to the bolt yield stress, resulting in greater wasted bolt performance and higher connection costs. Furthermore, due to the influence of bolt and connected component properties, as well as the tightening tool, the actual preload on the bolted connection after tightening will fluctuate around the theoretical value. Therefore, to ensure efficient bolt performance utilization and prevent overload, a safety factor is generally used. The preload should be 65% to 80%, meaning the preload should be within the range of formula (4). The safety factor range can be reduced as needed.

[0116] (4).

[0117] In the formula, This refers to the range of bolt preload.

[0118] Step 2: Establish the mapping relationship between preload, torque coefficient, and tightening torque to calculate the tightening torque of the bolt and provide the torque coefficient range requirements.

[0119] Establish the mapping relationship between bolt preload and tightening torque, as shown in formula (5), and obtain the tightening torque of the bolt connection. .

[0120] (5)

[0121] In the formula, For tightening torque; This is the torque coefficient for bolted connections. For preload, This refers to the nominal diameter of the bolt.

[0122] To ensure that the preload deviation of the bolt connection meets the requirements under tightening torque, the deviation ratio of the torque coefficient should be ≤20% (the maximum value in the deviation range is the benchmark). When the torque coefficient is large, the deviation range can be large, such as a torque coefficient range of 0.20~0.25. When the torque coefficient is small, the deviation range needs to be smaller, such as a torque coefficient range of 0.10~0.125.

[0123] Torque coefficient The friction coefficient of fasteners can be tested using a fastener friction coefficient tester. At least 10 sets of bolts should be tested for each type of bolt. The test bolts used in the test process should be actual production bolts. The test shims are used to simulate the connected parts. The material, hardness, roughness, etc. of the test shims should be consistent with the connected parts.

[0124] Based on the detected torque coefficient range and the preload range designed in step 1, the tightening torque is determined according to formula (5), where the torque coefficient in formula (5) is... Both the initial preload and the torque coefficient range are taken as the midpoint of the corresponding torque coefficient range and the preload range.

[0125] Furthermore, for bolted connections in special locations with complex operating conditions, the preload design requirements are close to the yield force. Since the torque coefficient is discrete, torque-based tightening of bolts is prone to yielding, leading to unstable bolted connections. Therefore, while meeting the design preload range, the tightening torque should be less than the yield torque.

[0126] The yield torque measurement should be performed on-site at the bolt connection, or a substitute sample should be fabricated. The material and technical requirements of the substitute sample should be consistent with the actual assembly. The tightening tool used to tighten the bolts should have real-time angle-torque data acquisition capabilities. Analyzing the tightening process data should begin with the tightening torque corresponding to 50% yield force. This saves time and avoids misjudgments caused by a large rate of change in the slope at the beginning of tightening. After starting the analysis, when the rate of change in the slope of the tightening curve exceeds 50%, the torque corresponding to this point is the yield torque. Figure 2 As shown. The formula for the rate of change of the slope of the tightening curve is (6):

[0127] (6),

[0128] In the formula, To determine the rate of change of the slope of the tightening curve. For the first One tightening torque, For the first One tightening torque, For the first One tightening torque, For the first Tighten at an angle. For the first Tighten at an angle. For the first Tighten at an angle.

[0129] The number of tightening torque tests should be no less than 5 sets each time, and the minimum value should be taken as the yield torque of the bolt each time. In order to reduce the possibility of yielding, the tightening torque should generally not exceed 90% of the yield torque.

[0130] Step 3: Based on the tightening sequence and preload design requirements, construct an elastic interaction matrix, optimize the initial preload, and verify its rationality using an ultrasonic preload testing device.

[0131] For bolted connections, firstly, based on the preload range designed in step 1, the median value of the preload range is taken as the initial preload. Then, the tightening sequence of the bolts on site is determined, such as sequential loading or cross loading. Next, based on the elastic interaction principle during tightening, the relationship between the initial preload and the target final preload is established. By checking whether the actual final preload is within the preload range as a constraint, the elastic interaction matrix is ​​iterated and the initial preload of the bolts is corrected to ensure that the final preload meets the design preload requirements. Figure 3 As shown, using this method, the bolt group can be tightened to a qualified condition in one go without the need for distributed tightening, thus ensuring high quality and efficiency in the tightening process.

[0132] The relationship between the initial preload and the final preload is given by formula (7):

[0133] (7)

[0134] In the formula, It is the target final preload matrix after the bolt is tightened. Each target final preload in the target final preload matrix must be within the preload range and the corresponding preload torque must be less than the yield torque. Each element in the target final preload matrix can be assigned a value according to actual needs. is the initial preload matrix applied when the bolt is tightened; A is the elastic interaction matrix;

[0135] Formula (7) expands to:

[0136] (8),

[0137] in:

[0138] (9),

[0139] This is a matrix recording the preload of all bolts tightened after the current bolt is loaded, during the bolt tightening process. For example, if the initial preload of bolts 1-4 is 20 kN, and the tightening sequence is 1 / 2 / 3 / 4, after tightening bolt 1, its preload is 20 kN; after tightening bolt 2, its preload becomes 19 kN and 20 kN; after tightening bolt 3, its preload becomes 18.5 kN, 19 kN, and 20 kN; and after tightening bolt 4, its preload becomes 18 kN, 18.5 kN, 19 kN, and 20 kN. The matrix then... for:

[0140] (10)

[0141] The preload force of the bolts after tightening is tested using an ultrasonic preload force testing device. After each bolt is tightened, the preload force of the tightened bolts is tested and recorded according to their numbers, until all bolts are tightened. A matrix is ​​then generated based on the test results. After the last bolt is tightened, determine whether the final preload of all corresponding bolts meets the preload requirement. If it does, output the elastic interaction matrix and the initial preload matrix. If it does not meet the requirement, recalculate the initial preload based on the target final preload matrix after bolt tightening and the new elastic interaction matrix until the preload design requirement is met.

[0142] Ultrasonic preload testing equipment testing requirements:

[0143] ① Bolt pretreatment: Grind the flat surfaces of the bolt head and tail to a surface roughness within Ra1.6, and the perpendicularity to the bolt shaft within 0.14mm. Then attach a piezoelectric ceramic sheet to the head.

[0144] ② Bolt calibration: A pressure sensor and a washer are clamped between the bolt and nut to make the clamping length equal to the actual length; the propagation time of ultrasonic waves in the bolt before and after tightening is recorded, and a preload calibration curve is fitted based on the test data to obtain the calibration coefficient.

[0145] ③ Bolt preload test: The test bolt and the calibration bolt should be in paper form. The echo duration should be zeroed within 15 minutes before the bolt is tightened. The preload can be tested on site according to the calibration coefficient.

[0146] Generally, elastic interactions are divided into positive and negative interactions. For flange bolt assemblies, the interaction between two adjacent bolts is negative, while the interaction between bolts in a symmetrical direction is positive. Typically, for flange bolt assemblies with a diameter <500mm, a complete experimental prototype can be replicated proportionally based on the actual components during tightening process development. However, for large-diameter (≥500mm) flange bolt assemblies, the positive interaction is not significant, and a simplified fan-shaped experimental prototype can be fabricated, such as... Figure 4 As shown, the effect of negative interaction becomes less obvious with more spacer bolts. The two bolts in the spacer are almost negligible. The through holes on the left and right sides can be used to tighten ordinary bolts to the test platform for testing. The tightening torque is generally 50 Nm. The main function is to fix the fan-shaped sample and avoid it from being subjected to positive elastic interaction.

[0147] Example 2

[0148] This invention provides a device for developing a tightening process for bolt assemblies, comprising:

[0149] Preload testing equipment is used to obtain the final preload of each bolt;

[0150] The controller, connected to the preload detection device, is configured to perform the method described in any one of Embodiment 1.

[0151] Example 3

[0152] This invention provides a tightening process development system for bolt assemblies, including a storage medium and a processor;

[0153] The storage medium is used to store instructions;

[0154] The processor is configured to operate according to the instructions to execute the method described in any one of Embodiment 1.

[0155] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0156] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0157] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0158] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0159] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

[0160] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for developing a tightening process for bolt assemblies, characterized in that, include: Based on the material properties of the bolt and the connected parts, the preload range of the bolt is calculated; The constraint is that the final preload of each bolt in the bolt group is within the preload range under the tightening torque corresponding to the initial preload. Based on the relationship between the target final preload matrix, the elastic interaction matrix and the initial preload matrix, the elastic interaction matrix is ​​continuously iterated, and the initial preload of each bolt in the initial preload matrix is ​​corrected to obtain the final initial preload of each bolt.

2. The method for developing a tightening process for bolt assemblies according to claim 1, characterized in that: The calculation method for the preload range of the bolt includes: Based on the material properties of the bolt and the connected parts, the critical load at which the bolt yields when tightened using the torque method, and the maximum load at which the surface of the contact area between the bolt and the connected parts does not crush are calculated. With the goal of ensuring that neither the bolt nor the connected object yields or crushes, the maximum allowable preload during the bolt connection process is calculated based on the critical load and the maximum load. Based on the maximum preload and the preset safety factor, the preload range of the bolt is calculated.

3. The method for developing a tightening process for bolt assemblies according to claim 2, characterized in that: The formula for calculating the critical load at which the bolt yields when tightening it using the torque method is as follows: ， In the formula, This refers to the critical load at which the bolt yields when tightened using the torque method. This refers to the bolt yield stress. The cross-sectional area of ​​the thread stress is... The cross-sectional area of ​​the thread stress The diameter of the corresponding equivalent circular cross section, For pitch, The coefficient of friction of the thread. The thread pitch diameter; The formula for calculating the maximum load that prevents crushing of the surface of the contact area between the bolt and the connected component is as follows: ， In the formula, The maximum load that prevents crushing of the surface of the connected parts and the bolt contact area. This is the surface compressive stress limit, which is the minimum stress required for the surface of the contact area between the bolt and the connected parts to crush. The outer diameter of the effective contact area between the bolt and the connected parts. The inner diameter of the effective contact area between the bolt and the connected parts; The formula for calculating the maximum allowable preload force during the bolt connection process is as follows: ， In the formula, This refers to the maximum preload force that can be applied during bolted connections. The formula for calculating the preload range of the bolt is: ， In the formula, This refers to the preload range of the bolt. For safety margin, the value is set between 65% and 80%.

4. The method for developing a tightening process for bolt assemblies according to claim 1, characterized in that: The mathematical expression for the relationship between the target final preload matrix, the elastic interaction matrix, and the initial preload matrix is: ， In the formula, The target final preload matrix, The initial preload matrix, For bolts The initial preload, For bolts The target final preload, This represents the total number of bolts. For a flexible interaction matrix, matrix elements The calculation formula is: ， In the formula, The final preload matrix is ​​formed by the final preload of all bolts in the bolt group; Repeat the following steps until all the final preloads in the last column of the final preload matrix are within the preload range: When the final preload matrix If the last column contains a final preload outside the preload range, then the initial preload of each bolt is corrected according to the relationship between the target final preload matrix, the elastic interaction matrix, and the initial preload matrix. Based on the corrected initial preload of each bolt, calculate the new tightening torque of each bolt; According to the predetermined tightening sequence, each bolt in the bolt group is tightened in turn according to the new tightening torque of each bolt. After each bolt is tightened, the final preload of the tightened bolts is obtained as a column of data in the final preload matrix. This process continues until all bolts are tightened, forming a new final preload matrix.

5. The method for developing a tightening process for bolt assemblies according to claim 4, characterized in that: The formula for calculating tightening torque is: ， In the formula, For tightening torque; This is the torque coefficient for bolted connections. For preload, This refers to the nominal diameter of the bolt.

6. The method for developing a tightening process for bolt assemblies according to claim 5, characterized in that: The deviation ratio of the torque coefficient is ≤20%. The formula for calculating the deviation ratio of the torque coefficient is: maximum torque coefficient - minimum torque coefficient / maximum torque coefficient.

7. The method for developing a tightening process for bolt assemblies according to claim 1, characterized in that: The constraints also include: The final tightening torque of each bolt is less than its corresponding yield torque.

8. The method for developing a tightening process for bolt assemblies according to claim 7, characterized in that: The method for calculating the yield torque includes: Calculate the rate of change of the slope of the tightening curve. The formula for calculating the rate of change of the slope of the tightening curve is: ， In the formula, The rate of change of the slope of the tightening curve. For the first One tightening torque For the first One tightening torque For the first One tightening torque For the first Tighten at an angle. For the first Tighten at an angle. For the first One tightening angle; When the rate of change of the slope of the tightening curve exceeds the set threshold, the tightening torque corresponding to the rate of change of the slope of the tightening curve is the yield torque.

9. A device for developing a tightening process for bolt assemblies, characterized in that, include: Preload testing equipment is used to obtain the final preload of each bolt; The controller, connected to the preload detection device, is configured to perform the method of any one of claims 1-8.

10. A tightening process development system for bolt assemblies, characterized in that, Including storage media and processor; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the method of any one of claims 1-8.

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