Assembly tightening method and tightening system for aircraft pipeline

Abstract

The tightening system comprises a parameter calling module and a parameter acquisition module, the parameter calling module is in communication connection with a first calculation module, the parameter acquisition module is in communication connection with a second calculation module, and the first calculation module and the second calculation module are connected to a comparison module in parallel; during use, a standard corner torque curve is obtained according to the specification and model of a to-be-screwed nut; calculating a standard fitting torque and a standard rotation angle according to the standard rotation angle torque curve; then, an actual corner torque curve of the nut to be tightened is obtained, and an actual corner is calculated according to the standard fitting torque and the actual corner torque curve; and finally, comparing the actual rotation angle with the standard rotation angle, and judging whether the nut to be tightened is regularly tightened or not. According to the method, the parameters used for judging whether the tightening process is standard or not can be read from the standard corner torque curve, and the actual torque in the tightening process is monitored through the standard parameters, so that whether tightening is in a composite standard or not is judged.

Description

Technical Field

[0001] The present application relates to the technical field of assembly equipment, and in particular to an assembly and tightening method and a tightening system for aircraft pipelines. Background Art

[0002] The aircraft piping system is a functional system formed by integrating and fixing conduits, pipe clamps, brackets, clamps and other accessories with system functional products in series or parallel on the fuselage structure. Its supporting rigidity is weak, the system is interconnected, the spatial distribution is extremely complex, the assembly is difficult, and the regulatory requirements are high. To ensure the service reliability and maintenance convenience of the aircraft piping system, the piping system assembly is mainly in the form of threaded connection, and the main assembly is carried out by applying torque, that is, by tightening the outer nut to generate axial preload. Under the action of the axial preload, the conical surface of the conduit and the conical surface of the pipe joint are in contact and squeezed to achieve the interlocking between the sealing surfaces, thereby achieving the sealing performance of the pipeline.

[0003] The preload and assembly specifications of pipeline connections play a significant role in the sealing performance and reliability of aircraft piping systems. Therefore, during aircraft piping assembly, it is necessary to control the preload and assembly specifications of the pipes and connectors. Traditional torque methods can only measure the final tightening torque and cannot monitor the compliance of the pipe assembly process. Furthermore, this method is suitable for tightening bolts with high connection stiffness but is not suitable for tightening the assembly of aircraft pipes with weak support stiffness.

[0004] Aircraft ducts have weak support stiffness and are affected by the narrow working space, requiring a multi-step tightening method. Existing technologies are affected by factors such as torque reaction force, eccentric load, and friction during assembly and tightening. When the applied torque is large, the pipeline will shift or deform during assembly, resulting in the inability to accurately measure the rotation angle of the assembly process, and thus unable to achieve precise and standardized tightening control based on the torque angle method. Summary of the Invention

[0005] The main purpose of this application is to provide an assembly and tightening method and a tightening system for aircraft pipes, aiming to solve the defects of poor standardization in the prior art.

[0006] This application achieves the above objectives through the following technical solutions:

[0007] A tightening method for aircraft pipelines, comprising the following steps:

[0008] According to the specifications and models of the nuts to be tightened, obtain the standard angle torque curve;

[0009] Calculating a standard fitting torque and a standard rotation angle according to the standard rotation angle torque curve;

[0010] Obtaining the actual angle torque curve of the nut to be tightened;

[0011] Calculating an actual rotation angle according to the standard fitting torque and the actual rotation angle torque curve;

[0012] The actual rotation angle is compared with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the specification.

[0013] Optionally, calculating the standard fitting torque and the standard rotation angle according to the standard rotation angle torque curve comprises the following steps:

[0014] Obtain standard angle torque curve;

[0015] Separating the standard angle torque curve into a first-stage standard angle torque curve and a second-stage standard angle torque curve; wherein the first-stage standard angle torque curve identifies the fitting stage, and the second-stage standard angle torque curve is used to identify the elastic tightening stage;

[0016] Calculating the slope k0 of the standard angle torque curve of the second stage;

[0017] Select any two adjacent points on the first stage standard angle torque curve and calculate the slope k of the two adjacent points respectively. m+1 and k m ;

[0018] If the slope k m+1 If the judgment formula is satisfied, then the slope k is taken m+1 The torque at the corresponding point is the standard fitting torque. Otherwise, the steps of randomly selecting two adjacent points on the standard rotation angle torque curve of the second stage and calculating the slopes of the two adjacent points are repeated until the standard fitting torque is obtained.

[0019] Optionally, the expression of the judgment formula is k m+1 -k m ≤0.1, and |k m+1 -k0|≤0.05; where k0 represents the slope of the standard angle torque curve in the second stage.

[0020] Optionally, obtaining an actual angle torque curve of a nut to be tightened includes the following steps:

[0021] Set the initial torque T0;

[0022] Obtain a standard angle torque curve, and set a torque threshold for each tightening step according to the standard angle torque curve and the initial torque T0;

[0023] The assembly of the nut to be tightened is completed according to the initial torque T0 and each of the torque thresholds, and an actual rotation angle torque curve of the nut to be tightened is obtained.

[0024] Optionally, setting a torque threshold for each tightening step according to the standard angle torque curve and the initial torque includes the following steps:

[0025] Set the initial torque, where the value range of the initial torque is 1-1.5Nm;

[0026] Obtain standard fitting torque angle curve;

[0027] Dividing the standard fitting torque angle curve into a plurality of tightening steps according to the rotation angle of each tightening step;

[0028] Get the maximum torque T1, T2, ..., T of each tightening step respectively n ; Where n represents the number of each tightening step;

[0029] The torque threshold of each tightening step is calculated according to the torque threshold calculation formula.

[0030] Optionally, the torque threshold calculation formula is expressed as T n =k*T n-1 ; Where k represents the calculation coefficient, and its value range is 0.7-0.8; T1=k*T0.

[0031] Optionally, assembling the nut to be tightened according to the initial torque T0 and each of the torque thresholds, and collecting an actual angle torque curve of the nut to be tightened, comprises the following steps:

[0032] Obtaining the initial torque T0 and the torque thresholds;

[0033] After the first tightening step is completed, when the actual torque value is greater than the initial torque T0, the torque curve of the first tightening step is collected;

[0034] After the second tightening step is completed, when the actual torque value is greater than the tightening threshold T1, the torque curve of the first tightening step is collected;

[0035] Control and complete the tightening operation of all tightening steps and obtain all torque curves;

[0036] The torque curves are spliced ​​together according to the order of the tightening steps to obtain the actual angle torque curve.

[0037] Optionally, calculating the actual rotation angle according to the standard fitting torque and the actual rotation angle torque curve comprises the following steps:

[0038] Obtain standard fitting torque and actual angle torque curves;

[0039] Obtaining a marking point on the actual rotation angle torque curve according to the standard fitting torque;

[0040] The rotation angle of the marked point is output as the actual rotation angle.

[0041] Optionally, comparing the actual rotation angle with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the specification includes the following steps:

[0042] Set the deviation redundancy value;

[0043] Calculating an upper deviation value and a lower deviation value of an angle according to the deviation redundancy value and the standard angle;

[0044] If the actual rotation angle is between the upper rotation angle deviation value and the lower rotation angle deviation value, it is determined that the assembly of the nut to be tightened meets the specification; otherwise, it is determined that it does not meet the specification.

[0045] Accordingly, the present application also discloses a tightening system based on the above tightening method, comprising:

[0046] The parameter retrieval module is used to obtain the standard angle torque curve according to the specifications and models of the nut to be tightened;

[0047] A first calculation module is used to calculate a standard fitting torque and a standard rotation angle according to the standard rotation angle torque curve;

[0048] A parameter acquisition module is used to obtain the actual angle torque curve of the nut to be tightened;

[0049] a second calculation module, configured to calculate an actual rotation angle according to the standard fitting torque and the actual rotation angle torque curve;

[0050] The comparison module is used to compare the actual rotation angle with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the specification.

[0051] Compared with the prior art, this application has the following beneficial effects:

[0052] The present application includes a parameter retrieval module and a parameter acquisition module, wherein the output end of the parameter retrieval module is communicatively connected to a first calculation module, and the output end of the parameter acquisition module is communicatively connected to a second calculation module, and the first calculation module and the second calculation module are connected in parallel to the comparison module;

[0053] Correspondingly, the present application also discloses a tightening method based on the above-mentioned tightening system, which first obtains a standard angle torque curve according to the specification and model of the nut to be tightened; then calculates the standard fitting torque and standard angle according to the initial torque and the standard angle torque curve; then obtains the actual angle torque curve of the nut to be tightened, and calculates the actual angle according to the initial torque, the standard fitting torque and the actual angle torque curve; finally, compares the actual angle with the standard angle to determine whether the nut to be tightened is tightened in accordance with the specification;

[0054] Compared with the existing technology, a series of parameters can be read from the standard angle torque curve to determine whether the tightening process is standard, such as initial torque, standard fitting torque and standard angle. These standard parameters can quickly determine whether the actual torque curve during the nut tightening process is qualified, that is, whether the nut tightening process meets the standards, thereby improving the standardization of assembly.

[0055] Secondly, since the technical solution described in this application can effectively improve the standardization of nut assembly, it can effectively improve the assembly quality of pipes in narrow spaces. In particular, for narrow spaces and pipes with weak support stiffness, this application can avoid the problem of part damage caused by excessive torque by effectively controlling the torque.

[0056] Finally, since the actual angle torque curve is collected in real time during the actual nut tightening process, the standard fitting torque and standard angle are used to determine whether the actual angle torque curve is qualified in real time, thereby effectively improving the real-time performance of nut tightening monitoring. In this way, an alarm is issued as soon as an abnormality in the assembly process is discovered, and the nut is loosened in the reverse direction and readjusted before tightening again, which improves the redundancy of the catheter assembly process and is conducive to improving the assembly quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic structural diagram of an assembly system for aircraft piping provided in Example 1 of the present application;

[0058] Figure 2 This is a flow chart of a tightening method for aircraft pipes provided in Example 2 of the present application;

[0059] Figure 3 This is the calculation principle diagram of standard fitting torque;

[0060] Figure 4 This is the calculation principle diagram of the torque threshold;

[0061] Figure 5 is the actual angle torque curve;

[0062] The purpose, features and advantages of this application will be further explained with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0063] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0064] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0065] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0066] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "robot coordinate system and / or m" as an example, it includes the robot coordinate system scheme, or the m scheme, or the scheme in which the robot coordinate system and m are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0067] Example 1

[0068] Reference Figure 1 This embodiment discloses an assembly and tightening system for aircraft pipelines, comprising a parameter retrieval module and a first calculation module. The parameter retrieval module is configured to obtain a standard angle torque curve based on the specifications and model of the nut to be tightened. The parameter retrieval module is communicatively connected to the first calculation module to receive the standard angle torque curve. The first calculation module calculates a standard fitting torque and a standard angle based on the standard angle torque curve.

[0069] The assembly and tightening system further includes a parameter acquisition module and a second calculation module, wherein the parameter acquisition module is used to obtain an actual rotation angle torque curve of the nut to be tightened; the parameter acquisition module is communicatively connected to the second calculation module to receive the actual rotation angle torque curve, and the second calculation module also receives the standard fitting torque, thereby calculating the actual rotation angle based on the standard fitting torque and the actual rotation angle torque curve;

[0070] The assembly and tightening system further includes a comparison module, which is used to compare the actual rotation angle with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the specification.

[0071] Implementation Method 2

[0072] Reference Figure 2 The present application discloses a method for assembling and tightening aircraft pipes, comprising the following steps:

[0073] It should be noted that this application will provide a detailed description of the technical solutions described in this application by giving examples;

[0074] S1. Obtain a standard angle torque curve according to the specifications and models of the nut to be tightened;

[0075] First, the specifications of the nut to be tightened are determined, and the corresponding standard angle torque curve is retrieved from the database according to the specification parameters of the nut to be tightened;

[0076] It should be noted that the standard angle-torque curve is obtained by performing a tightening test using a nut with the same specifications as the nut to be tightened. It can also be selected from angle-torque curves collected during daily assembly.

[0077] S2. Calculating a standard fitting torque and a standard rotation angle according to the standard rotation angle torque curve;

[0078] S21, obtaining a standard angle torque curve;

[0079] S22, separating the standard rotation angle torque curve into a first-stage standard rotation angle torque curve and a second-stage standard rotation angle torque curve; wherein the first-stage standard rotation angle torque curve indicates a fitting stage, and the second-stage standard rotation angle torque curve indicates an elastic tightening stage;

[0080] Engineering practice shows that nut tightening can be roughly divided into three stages: the screw-in stage, the fitting stage, and the elastic tightening stage. Workers manually divide the standard angle torque curve to obtain a three-end curve. The torque change in the screw-in stage is small and can be ignored.

[0081] The curve of the fitting stage is used as the standard angle torque curve of the first stage, and the curve of the elastic tightening stage is used as the standard angle torque curve of the second stage;

[0082] S23, calculating the slope k0 of the standard angle torque curve of the second stage;

[0083] Based on engineering practice, it is known that in the elastic tightening stage, the torque angle changes in a positive correlation, that is, the standard angle torque curve of the second stage is an inclined straight line. After separating the standard angle torque curve of the second stage, its slope k0 is automatically calculated by a computer;

[0084] S24. Randomly select two adjacent points on the standard angle torque curve of the first stage, and calculate the slope k of the two adjacent points respectively. m+1 and k m ;

[0085] Obtain the first stage standard angle torque curve, randomly select two points on the first stage standard angle torque curve, such as points marked m and m+1, and then calculate the slope k of the two points m+1 and k m ;

[0086] S25, if the slope k m+1 If the judgment formula is satisfied, then the slope k is taken m+1 The torque at the corresponding point is the standard fitting torque. Otherwise, the steps of randomly selecting two adjacent points on the standard rotation angle torque curve of the first stage and calculating the slopes of the two adjacent points are repeated until the standard fitting torque is obtained.

[0087] Retrieve the judgment formula, the expression of the judgment formula is k m+1 -k m ≤0.1, and |k m+1 -k0|≤0.05; where k0 represents the slope of the standard angle torque curve in the second stage;

[0088] If the slope k m+1 If the judgment formula is satisfied, then the slope k is taken m+1 The torque at the corresponding point is the standard fitting torque, and the angle corresponding to the point is output as the standard angle. Otherwise, random points are repeatedly selected until the standard fitting torque is obtained.

[0089] In a specific embodiment, the principle diagram of point calculation is as follows: Figure 3 As shown;

[0090] In a specific embodiment, the slope of the tightening curve at position D meets the requirements, so the fitting torque of the catheter tightening process curve is 8.8 Nm and the rotation angle is 49°; when the fitting torque is set to 8.8 Nm within the range allowable for measurement error, the corresponding reference angle range is 49±5°.

[0091] S3, obtaining an actual angle torque curve of the nut to be tightened;

[0092] S31, setting the initial torque T0;

[0093] The initial torque T0 is determined according to the actual situation. It should be noted that the value range of the initial torque is 1-1.5Nm;

[0094] S32, obtaining a standard angle torque curve, and setting a torque threshold for each tightening step according to the standard angle torque curve and the initial torque T0;

[0095] S321, setting an initial torque, wherein the value range of the initial torque is 1-1.5 Nm;

[0096] It should be noted that the value range of the initial torque is 1-1.5Nm, and the value can be selected within the above range according to actual needs, such as 1.2Nm;

[0097] S322, obtaining a standard fitting torque angle curve;

[0098] S323, dividing the standard fitting torque angle curve into a plurality of tightening steps according to the rotation angle of each tightening step;

[0099] Due to the obstruction of external parts, the tightening angle is limited each time the nut is tightened. For example, the angle of a single tightening step of some nuts is 10°, and the rotation angle of tools such as wrenches used to tighten the nuts is 10°, while others are 15°. The angle of each tightening step is determined according to the actual working conditions.

[0100] S324, respectively obtain the maximum torque T1, T2, ..., T of each tightening step n ; Where n represents the number of each tightening step;

[0101] Obtain the standard fitting torque angle curve of each tightening step respectively, and then obtain the maximum torque T1, T2, ..., T of each tightening step respectively. n ; Where n represents the number of each tightening step;

[0102] S325. Calculate the torque threshold of each tightening step according to the torque threshold calculation formula.

[0103] Get the maximum torque T1, T2, ..., T of each tightening step n ;

[0104] The torque threshold calculation formula is expressed as T n =k*T n-1 ; Where k represents the calculation coefficient, and its value range is 0.7-0.8; T1=k*T0.

[0105] According to the above formula, the torque threshold of each tightening step can be calculated;

[0106] In a specific embodiment, the torque threshold is set as follows: Figure 4 As shown;

[0107] S33 , assembling the nut to be tightened according to the initial torque T0 and the torque thresholds, and collecting an actual rotation angle torque curve of the nut to be tightened.

[0108] Obtain the set initial torque T0 and the calculated torque thresholds, and assemble the nut to be tightened according to the above figures;

[0109] Specifically, if the initial torque is set to 1.2 Nm, when the actual torque detected is greater than 1.2 Nm, the relevant torque parameters and angle parameters begin to be collected and uploaded until the tightening step is completed;

[0110] Then the second tightening step begins, and the torque threshold T1 of the second tightening step is extracted at the same time; when the detected torque value is greater than the torque threshold T1, the relevant torque parameters and angle parameters begin to be collected and uploaded until the tightening step ends;

[0111] All relevant operations of the tightening steps are performed simultaneously to obtain the actual angle-torque curve of the nut to be tightened.

[0112] As the tightening process continues, the torque of the nut will continue to increase. However, when a new tightening step begins, if the data is collected again from the initial torque, the discreteness of the data will increase. Therefore, by setting the torque threshold, some torque values ​​that are too small can be excluded, which not only reduces the amount of data and helps improve the calculation efficiency, but also helps to improve the anti-interference ability of the data, thereby adapting to the tightening characteristics of weak support stiffness pipelines and improving the accuracy of data calculation.

[0113] In a specific embodiment, the actual angle torque curve is as follows: Figure 5 As shown;

[0114] S4. Calculating an actual rotation angle according to the standard fitting torque and the actual rotation angle torque curve;

[0115] S41, obtaining standard fitting torque and actual angle torque curves;

[0116] Obtaining the standard fitting torque obtained in step S25 and the actual angle torque curve obtained in step S3;

[0117] S42, obtaining a marking point on the actual rotation angle torque curve according to the standard fitting torque;

[0118] A point is taken on the actual angle torque curve according to the standard fitting torque, and the calculated point is the marking point;

[0119] S43: Output the turning angle of the marked point as the actual turning angle.

[0120] Calculate the rotation angle of the marked point and output it as the actual rotation angle;

[0121] That is, the standard fitting torque calculated in step S25 is 8.8 Nm. Figure 4 The corresponding rotation angle is 73°;

[0122] S5. Compare the actual rotation angle with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the standard.

[0123] S51, setting a deviation redundancy value;

[0124] Set the deviation redundancy value according to actual needs, such as the deviation redundancy is +5 and -5°;

[0125] S52, calculating an upper deviation value and a lower deviation value of the turning angle according to the deviation redundancy value and the standard turning angle;

[0126] The upper deviation value and the lower deviation value of the angle are calculated respectively by combining the standard angle and the deviation redundancy value;

[0127] S53: If the actual rotation angle is between the upper rotation angle deviation value and the lower rotation angle deviation value, it is determined that the assembly of the nut to be tightened meets the specification; otherwise, it is determined that it does not meet the specification.

[0128] In a specific embodiment, the rotation angle of 73° is obviously not within the range of 49±5°, so the assembly does not meet the specifications.

[0129] Compared with the existing technology, a series of parameters can be read from the standard angle torque curve to determine whether the tightening process is standard, such as the standard fitting torque and standard angle. These standard parameters can quickly determine whether the actual torque curve during the nut tightening process is qualified, that is, whether the nut tightening process meets the standards, thereby improving the standardization of assembly.

[0130] Secondly, since the technical solution described in this application can effectively improve the standardization of nut assembly, it can effectively improve the assembly quality of pipes in narrow spaces. In particular, for narrow spaces and pipes with weak support stiffness, this application can avoid the problem of part damage caused by excessive torque by effectively controlling the torque.

[0131] Finally, since the actual angle torque curve is collected in real time during the actual tightening process of the nut, the standard fitting torque and standard angle are used to determine whether the actual angle torque curve is qualified in real time, thereby effectively improving the real-time performance of nut tightening monitoring. In this way, an alarm is issued as soon as an abnormality in the assembly process is discovered, and the nut is loosened in the reverse direction and readjusted before tightening again, which increases the redundancy in the bolt assembly process and is conducive to improving the assembly quality.

[0132] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A tightening method for aircraft pipes, characterized in that: The following steps are involved: According to the specifications and models of the nuts to be tightened, obtain the standard angle torque curve; Calculating a standard fitting torque and a standard rotation angle according to the standard rotation angle torque curve; Obtaining the actual angle torque curve of the nut to be tightened; Calculating an actual rotation angle according to the standard fitting torque and the actual rotation angle torque curve; The actual rotation angle is compared with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the specification.

2. The tightening method according to claim 1, characterized in that: The step of calculating the standard fitting torque and the standard rotation angle according to the standard rotation angle torque curve comprises the following steps: Obtain standard angle torque curve; Separating the standard angle torque curve into a first-stage standard angle torque curve and a second-stage standard angle torque curve; wherein the first-stage standard angle torque curve identifies the fitting stage, and the second-stage standard angle torque curve is used to identify the elastic tightening stage; Calculating the slope k0 of the standard angle torque curve of the second stage; Select any two adjacent points on the first stage standard angle torque curve and calculate the slope k of the two adjacent points respectively. m+1 and k m ; If the slope k m+1 If the judgment formula is satisfied, then the slope k is taken m+1 The torque at the corresponding point is the standard fitting torque. Otherwise, the steps of randomly selecting two adjacent points on the standard rotation angle torque curve of the second stage and calculating the slopes of the two adjacent points are repeated until the standard fitting torque is obtained.

3. The tightening method according to claim 2, characterized in that: The expression of the judgment formula is k m+1 -k m ≤0.1, and |k m+1 -k0|≤0.05; where k0 represents the slope of the standard angle torque curve in the second stage.

4. The tightening method according to claim 1, characterized in that: The method of obtaining the actual angle torque curve of the nut to be tightened comprises the following steps: Set the initial torque T0; Setting a torque threshold for each tightening step according to the initial torque T0; The assembly of the nut to be tightened is completed according to the initial torque T0 and each of the torque thresholds, and an actual rotation angle torque curve of the nut to be tightened is obtained.

5. The tightening method according to claim 4, characterized in that: The step of setting a torque threshold for each tightening step according to the standard angle torque curve and the initial torque comprises the following steps: Set the initial torque, where the value range of the initial torque is 1-1.5Nm; Obtain standard fitting torque angle curve; Dividing the standard fitting torque angle curve into a plurality of tightening steps according to the rotation angle of each tightening step; Get the maximum torque T1, T2, ..., T of each tightening step respectively n ; Where n represents the number of each tightening step; The torque threshold of each tightening step is calculated according to the torque threshold calculation formula.

6. The tightening method according to claim 5, characterized in that: The torque threshold calculation formula is expressed as T n =k*T n-1 ; Where k represents the calculation coefficient, and its value range is 0.7-0.8; T1=k*T0.

7. The tightening method according to claim 4, characterized in that: The method of assembling the nut to be tightened according to the initial torque T0 and the torque thresholds, and collecting the actual angle torque curve of the nut to be tightened, comprises the following steps: Obtaining the initial torque T0 and the torque thresholds; After the first tightening step is completed, when the actual torque value is greater than the initial torque T0, the torque curve of the first tightening step is collected; After the second tightening step is completed, when the actual torque value is greater than the tightening threshold T1, the torque curve of the first tightening step is collected; Control and complete the tightening operation of all tightening steps and obtain all torque curves; The torque curves are spliced ​​together according to the order of the tightening steps to obtain the actual angle torque curve.

8. The tightening method according to claim 1, characterized in that: The calculating the actual rotation angle according to the standard fitting torque and the actual rotation angle torque curve comprises the following steps: Obtain standard fitting torque and actual angle torque curves; Obtaining a marking point on the actual rotation angle torque curve according to the standard fitting torque; The rotation angle of the marked point is output as the actual rotation angle.

9. The tightening method according to claim 1, characterized in that: The comparing the actual rotation angle with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the specification includes the following steps: Set the deviation redundancy value; Calculating an upper deviation value and a lower deviation value of an angle according to the deviation redundancy value and the standard angle; If the actual rotation angle is between the upper rotation angle deviation value and the lower rotation angle deviation value, it is determined that the assembly of the nut to be tightened meets the specification; otherwise, it is determined that it does not meet the specification.

10. An assembly and tightening system for aircraft piping, characterized in that: include: The parameter retrieval module is used to obtain the standard angle torque curve according to the specifications and models of the nut to be tightened; A first calculation module is used to calculate a standard fitting torque and a standard rotation angle according to the standard rotation angle torque curve; A parameter acquisition module is used to obtain the actual angle torque curve of the nut to be tightened; a second calculation module, configured to calculate an actual rotation angle according to the standard fitting torque and the actual rotation angle torque curve; The comparison module is used to compare the actual rotation angle with the standard rotation angle to determine whether the nut to be tightened is tightened in accordance with the specification.

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