Anti-loosening safety checking method for stay bolt assembly type rotor

Abstract

The invention provides an anti-loosening safety checking method of a stay bolt assembly type rotor, and belongs to the technical field of safety checking of the stay bolt assembly type rotor, and the method comprises the steps: supposing that the pressure intensity on an annular contact surface between parts on the rotor is uniformly distributed, firstly, carrying out the preliminary estimation of the design of the rotor, if the first loosening torque and the first safety coefficient do not meet the requirements, the rotor structure needs to be redesigned; the running load of the rotor is comprehensively considered when the finite element model is established, and the real running environment of the rotor is simulated; then, obtaining contact parameters of a contact surface through finite element calculation, re-calculating whether the loosening torque and the safety coefficient meet the requirements after the actual operation load of the rotor is simulated according to the contact parameters, and if the simulated loosening torque and the safety coefficient do not meet the requirements, re-designing the rotor structure; and when a closed bonding annular area exists in the contact surface, it is considered that the contact surface is not loosened, and the anti-loosening design of the contact surface is qualified. And the anti-loosening safety calculation precision and reliability are ensured.

Description

Technical Field

[0001] This application belongs to the technical field of safety verification of tie-rod bolt assembled rotors, and particularly relates to a method for preventing loosening and safety verification of tie-rod bolt assembled rotors. Background Art

[0002] In recent years, the old-fashioned Roots blowers in the sewage treatment industry have been gradually phased out, and high-speed centrifugal blowers with low noise, high efficiency, and convenient adjustment have been adopted. Most of the rotors of such blowers are equipped with single-stage centrifugal semi-open impellers, and the impellers are assembled with the motor shaft by interference fit, tie-rod bolts, etc. When operating, they are subjected to loads such as rotational centrifugal force, aerodynamic force, forced vibration caused by shaft eccentricity, and torque. At present, the development trend of high-speed centrifugal blowers is to use a central tie-rod bolt that is more convenient for installation and disassembly to achieve the assembly of the rotating shaft and the impeller. For the rotor of a blower with a power of more than 100KW, there is a contradiction between its strength design and shaft power transmission: the tie-rod bolt has to bear a large initial tensile stress to compress the axial mating surfaces of the impeller, so that the generated frictional force is used to transmit torque, which greatly weakens the strength reserve of the stress concentration part of the tie-rod. Therefore, how to reduce the stress of the rotor during the design stage and at the same time transmit the shaft power from the motor side to the impeller as required to prevent the rotor components from loosening has become an important issue.

[0003] Different from the traditional integral rotor, the tie-rod combined rotor mainly relies on the pre-tightening force provided by the tie-rod bolts to fasten the rotor components such as the impeller, thrust disk, fan, and shaft sleeve into a whole, and uses a central tie-rod to connect the wheel discs of each stage in series. For this combined rotor structure, although it has the advantages of convenient assembly and maintenance, etc., there are multiple discontinuous contact interfaces in the structure, and it is very difficult to describe it with a unified model, which brings great difficulties to the in-depth research of the tie-rod rotor.

[0004] At present, there are mainly two methods for studying the contact problem, namely establishing an analytical model and carrying out numerical calculations. The analytical method usually relies on the GW model and various improved models based on it, such as the MB fractal contact model, the GW correction model, etc. The determination of parameters needs to rely on experimental and statistical data, which is more difficult to implement, and the accuracy of the results is also difficult to guarantee. At present, the calculation model based on the frictional torque generated by the bolt pre-tightening force cannot accurately calculate the contact state and data of the contact surface, affecting the reliability of the rotor anti-loosening safety verification. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0006] In view of this, according to an embodiment of the present application, a method for preventing loosening and safety verification of a tie-rod bolt assembled rotor is proposed, including:

[0007] The method for anti-loosening safety check of a pull rod bolt assembled rotor includes:

[0008] Obtain the first loosening torque and the first safety factor of the contact surface on the rotor;

[0009] Establish a finite element model of the rotor;

[0010] Conduct finite element calculations;

[0011] Output the contact state of the contact surface;

[0012] Among them, the contact surface is the friction contact surface in the rotor.

[0013] In a feasible implementation manner, the steps of obtaining the first loosening torque and the first safety factor of the contact surface of the rotor include:

[0014] Obtain the pressure on the contact surface;

[0015] Arbitrarily take a differential element on the contact surface;

[0016] Obtain the loosening torque of the differential element;

[0017] Integrate the differential element within the contact surface to obtain the first loosening torque.

[0018] In a feasible implementation manner, the steps of obtaining the first loosening torque and the first safety factor of the contact surface of the rotor further include:

[0019] Obtain the first safety factor according to the first loosening torque;

[0020] When the first safety factor meets the requirements, establish a finite element model;

[0021] When the first safety factor does not meet the requirements, the anti-loosening design is unqualified.

[0022] In a feasible implementation manner, the steps of establishing a finite element model of the rotor include:

[0023] Build a three-dimensional model according to the structure of the rotor;

[0024] Set the material parameters of each part inside the rotor;

[0025] Apply loads such as bolt pre-tightening force, gravity, centrifugal force, temperature, aerodynamic force, etc. and displacement boundary conditions under operating conditions;

[0026] Obtain the finite element model;

[0027] In the finite element model, set the bolt and the rotating shaft as bonded contacts, and set all the contact surfaces inside the rotor as friction contacts.

[0028] In a feasible implementation manner, the steps of performing finite element calculation include:

[0029] Equivalent the maximum pressure on the contact surface to the average pressure to obtain the second loosening torque;

[0030] Obtain the second safety factor according to the second loosening torque;

[0031] When the second safety factor meets the requirements, output the contact state of the contact surface;

[0032] When the second safety factor does not meet the requirements, the anti-loosening design is unqualified.

[0033] In a feasible implementation manner, the steps of performing finite element calculation further include:

[0034] Select the maximum value of the positive pressure on the contact surface to obtain the maximum static friction force per unit area of the contact surface;

[0035] When the maximum static friction force per unit area is greater than the maximum friction stress, output the contact state of the contact surface;

[0036] When the maximum static friction force per unit area is less than the maximum friction stress, the anti-loosening design is unqualified.

[0037] In a feasible implementation manner, the anti-loosening safety check method for the tie rod bolt assembled rotor further includes:

[0038] When the result of the finite element calculation does not meet the requirements, perform refined calculation according to the finite element analysis result;

[0039] Obtain the third loosening torque and the third safety factor.

[0040] In a feasible implementation manner, the steps of performing refined calculation according to the finite element analysis result to obtain the third loosening torque and the third safety factor include:

[0041] Obtain the maximum static friction torque of each unit on the contact surface;

[0042] Superimpose the maximum static friction torques of all units to obtain the third loosening torque;

[0043] Obtain the third safety factor according to the third loosening torque;

[0044] When the third safety factor meets the requirements, output the contact state of the contact surface;

[0045] When the third safety factor does not meet the requirements, the anti-loosening design is unqualified.

[0046] In a feasible implementation manner, the maximum static friction torque of the unit is obtained by calculating based on the normal pressure of each node on the contact surface, the node coordinate information, the unit information, and the area.

[0047] In a feasible implementation manner, when the contact state of the output friction contact surface is that there is a closed bonded annular area, the anti-loosening design of the contact surface is qualified;

[0048] When the contact state of the output friction contact surface is that there is no closed bonded annular area, the anti-loosening design is unqualified.

[0049] A method for anti-loosening safety check of a tie rod bolt assembled rotor according to the present application has the following beneficial effects compared with the prior art:

[0050] The method for anti-loosening safety check of the tie rod bolt assembled rotor provided by the embodiment of the present application assumes that under the action of the bolt pre-tightening force, the pressure distribution on the annular contact surface between the parts on the rotor is uniform. Without considering the actual operating load of the rotor, the design of the rotor is initially estimated. If the first loosening torque and the first safety factor do not meet the requirements, the rotor structure needs to be redesigned; when establishing the finite element model, the operating load of the rotor is comprehensively considered to simulate the real operating environment of the rotor; then, the contact parameters of the contact surface are obtained through finite element calculation, and according to the contact parameters, it is calculated again whether the loosening torque and the safety factor after simulating the actual operating load of the rotor meet the requirements. If the simulated loosening torque and the safety factor do not meet the requirements, the rotor structure needs to be redesigned; when there is a closed bonded annular area on the contact surface, it is considered that the contact surface does not produce loosening, and the anti-loosening design of this contact surface is qualified. By combining the mathematical model with the finite element model, the contact states of each component of the rotor calculated are closer to the actual situation, the anti-loosening safety considers the load more comprehensively, and at the same time takes into account the strength design requirements of the rotor components, the calculation results are more accurate, ensuring the calculation accuracy and reliability of the anti-loosening safety. Description of the Drawings

[0051] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. And throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0052] Figure 1 It is a schematic step flow chart of a method for anti-loosening safety check of a tie rod bolt assembled rotor according to an embodiment provided by the present application;

[0053] Figure 2 It is a schematic diagram of a differential unit on the annular contact surface represented in polar coordinates in a method for anti-loosening safety check of a tie rod bolt assembled rotor according to an embodiment provided by the present application; Detailed implementation manners

[0054] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application 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 thus should not be construed as a limitation to the present application.

[0055] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined.

[0056] In the present application, unless otherwise clearly specified and limited, the terms such as "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0057] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0058] As Figure 1 shown, according to an embodiment of the present application, a method for anti-loosening safety verification of a tie rod bolt assembled rotor is proposed, including:

[0059] Obtaining the first loosening torque and the first safety factor of the contact surface on the rotor;

[0060] Establishing a finite element model of the rotor;

[0061] Performing finite element calculation;

[0062] Outputting the contact state of the contact surface;

[0063] Wherein, the contact surface is an annular friction contact surface in the rotor.

[0064] The anti-loosening safety checking method for the tie-rod bolt assembled rotor provided by the embodiment of the present application assumes that under the action of the bolt pre-tightening force, the pressure distribution on the annular contact surface between the parts on the rotor is uniform. Without considering the actual operating load of the rotor, the design of the rotor is initially estimated. If the first loosening torque and the first safety factor do not meet the requirements, the rotor structure needs to be redesigned; when establishing the finite element model, the operating load of the rotor is comprehensively considered to simulate the real operating environment of the rotor; then, the contact parameters of the contact surface are obtained through finite element calculation, and whether the loosening torque and the safety factor after simulating the actual operating load of the rotor meet the requirements are calculated again according to the contact parameters. If the simulated loosening torque and safety factor do not meet the requirements, the rotor structure needs to be redesigned; when there is a closed bonded annular area on the contact surface, it is considered that the contact surface does not loosen, and the anti-loosening design of this contact surface is qualified. By combining the mathematical model with the finite element model, the contact states of each component of the rotor calculated are closer to the actual situation, the anti-loosening safety considers the load more comprehensively, and takes into account the strength design requirements of the rotor components, the calculation results are more accurate, ensuring the calculation accuracy and reliability of the anti-loosening safety.

[0065] The assembled rotor includes tie-rod bolts, and the impeller, thrust disc, fan and rotating shaft are sequentially connected by the pre-tightening action of the tie-rod bolts. The friction contact surfaces between adjacent two parts are all closely-fitting annular friction contact surfaces. When the motor starts, the rotating shaft of the motor transmits torque by relying on the friction force of each part contact surface. When the friction force of a certain contact surface is greater than the maximum static friction force, the contact surface slips, that is, the two parts corresponding to the contact surface become loose. When the static friction force of the contact surface reaches the maximum static friction force, it is the critical state of sliding of the contact surface. By calculating the critical friction torque of the contact surface to slip, that is, the loosening torque, and comparing it with the input torque of the motor, the anti-loosening safety factor is obtained, and then by judging whether the anti-loosening safety factor meets the requirements, it is judged whether the anti-loosening design of the parts corresponding to the contact surface is qualified.

[0066] It should be noted that since there are multiple annular friction contact surfaces in the whole rotor, it is necessary to check all the friction contact surfaces in the rotor. If all the friction contact surfaces meet the requirements, the anti-loosening design of the whole rotor is qualified.

[0067] Specifically, the contact states in the finite element are divided into far away, approaching, bonding and sliding states.

[0068] In a feasible implementation manner, the steps of obtaining the first loosening torque and the first safety factor of the contact surface of the rotor include:

[0069] Obtain the pressure on the contact surface; Equivalent the pressure of the annular contact surface between the parts on the rotor to a uniform distribution;

[0070] Arbitrarily select a differential element on the contact surface; establish a polar coordinate system on the annular contact surface, and then arbitrarily select a differential element within the annular contact surface;

[0071] Obtain the loosening torque of the differential element; calculate the loosening torque of the differential element according to the formula T i = μ·N·ρ·ρ·dθ·dρ;

[0072] Integrate the differential element within the contact surface, and calculate the first loosening moment according to the formula

[0073] In this technical solution, assuming that the pressure generated by the bolt pre-tightening force on the contact surface is evenly distributed, obtain the loosening torque of the selected differential element through the force analysis of the differential element, integrate the differential element within the annular contact surface to obtain the first loosening moment, and perform a preliminary estimation before the finite element simulation.

[0074] In this technical solution, when calculating the first loosening moment, such as Figure 2 , first establish a polar coordinate within the annular contact surface and arbitrarily select a point P, solve using the polar coordinate system, and represent it with the radial coordinate ρ and the circumferential coordinate θ. Take a differential element PABC on the annular contact surface, the length of OP is ρ, the length of PC is dρ, and the length of PA is ρdθ. Assume that the normal pressure on the micro-element is N, T i is the loosening torque, μ is the friction coefficient, R is the outer diameter of the contact surface, r is the inner diameter of the contact surface, T 输入 represents the input torque, F is the bolt pre-tightening force, and S is the safety factor.

[0075] In a feasible implementation manner, the steps of obtaining the first loosening moment and the first safety factor of the contact surface of the rotor further include:

[0076] Obtain the first safety factor according to the first loosening moment; assume that when the pressure on the annular contact surface between the parts on the rotor is evenly distributed, the pressure on the contact surface can be approximated as the ratio of the bolt pre-tightening force to the area of the annular contact surface, that is, calculate the first safety factor according to the formula ;

[0077] When the first safety factor meets the requirements, establish a finite element model; assume that when the rotor is not subject to any load, if it can meet the first safety factor, then perform subsequent finite element simulation calculations;

[0078] When the first safety factor does not meet the requirements, the anti-loosening design is unqualified.

[0079] ​In this technical solution, it is assumed that under the action of the pre-tightening force of the tie rod bolts, the pressure distribution on the annular contact surface between the rotor parts is uniform. At this time, the pressure on the contact surface can be approximately regarded as the ratio of the bolt pre-tightening force to the area of the annular contact surface. According to the calculated first loosening torque, the first safety factor can be quickly calculated, and the calculation is simple and the difficulty is low. When the calculated first safety factor meets the requirements, it means that the anti-loosening design of this contact surface is qualified. When the first safety factor does not meet the requirements, the anti-loosening design of the rotor on this contact surface is unqualified and needs to be redesigned.

[0080] Specifically, when the first safety factor is greater than 1, it meets the anti-loosening design requirements.

[0081] In a feasible implementation manner, the steps of establishing a finite element model of the rotor include:

[0082] Build a three-dimensional model according to the structure of the rotor;

[0083] Set the material parameters of each part inside the rotor;

[0084] Apply loads such as bolt pre-tightening force, gravity, centrifugal force, temperature, aerodynamic force, etc. and displacement boundary conditions under the operating conditions;

[0085] Obtain the finite element model;

[0086] In the finite element model, set the bolt and the rotating shaft as bonded contacts, and set all the contact surfaces inside the rotor as frictional contacts.

[0087] In this technical solution, first build a three-dimensional model according to the rotor structure. Considering that in actual operation, the rotor is affected by loads such as gravity, centrifugal force, mass eccentricity, local high temperature, and airflow excitation, the pressure distribution on the annular contact surface between parts is uneven. The contact area between the rotor parts is unknown and instantaneously changing, which is not only determined by the pre-tightening force of the tie rod bolts, but also related to loads, materials, boundary conditions, and other factors. By using the finite element method, simulate the real operating environment of the rotor, apply loads such as bolt pre-tightening force, centrifugal force, gravity, temperature, and aerodynamic force, comprehensively consider the operating loads of the rotor, establish a finite element model, and then set the bolt and the rotating shaft as bonded contacts, and set all the contact surfaces inside the rotor as frictional contacts to ensure the accuracy and reliability of the simulation calculation results.

[0088] In a feasible implementation manner, the steps of performing finite element calculation include:

[0089] Equivalent the maximum pressure on the contact surface to the average pressure to obtain the second loosening torque;

[0090] Obtain the second safety factor according to the second loosening torque;

[0091] When the second safety factor meets the requirements, output the contact state of the contact surface;

[0092] If the second safety factor does not meet the requirements, the anti-loosening design is unqualified.

[0093] In this technical solution, the first determination method and steps of the finite element calculation results are specifically given. Conservatively select the maximum pressure on the contact surface as the average pressure of the contact surface, calculate the second loosening torque, and then calculate the second safety factor from the second loosening torque; when the second safety factor meets the requirements, the anti-loosening design of this contact surface is qualified, and the contact state of the contact surface is output; when the second safety factor does not meet the requirements, the anti-loosening design is unqualified and needs to be redesigned.

[0094] Specifically, when the second safety factor is greater than 1, it meets the requirements of the anti-loosening design.

[0095] In a feasible implementation manner, the steps of performing finite element calculation further include:

[0096] Select the maximum value of the positive pressure on the contact surface to obtain the maximum static friction force per unit area of the contact surface; according to the formula Calculate the second loosening torque, that is, the maximum friction stress output by the finite element calculation; the maximum static friction value represents the torque-bearing capacity of this position, and compare the maximum static friction force with the maximum friction stress output by the finite element calculation;

[0097] When the maximum static friction force per unit area is greater than the maximum friction stress, output the contact state of the contact surface;

[0098] When the maximum static friction force per unit area is less than the maximum friction stress, the anti-loosening design is unqualified.

[0099] In this technical solution, the second determination method and steps of the finite element calculation results are specifically given. Carry out finite element calculation to obtain the contact parameters of the contact surface of the rotor part, and output the normal pressure and friction stress of the contact surface. Select the maximum value of the positive pressure on the contact surface and calculate the maximum static friction force per unit area. The maximum static friction value represents the torque-bearing capacity of this position, and compare the maximum static friction force with the maximum friction stress output by the finite element calculation; when the friction stress is less than the maximum static friction force per unit area, that is, when the second loosening torque is less than the maximum static friction force per unit area, it meets the requirements of the anti-loosening design; when the second loosening torque is greater than the maximum static friction force per unit area, the anti-loosening design of this contact surface is unqualified and needs to be redesigned.

[0100] It should be noted that if the finite element simulation results meet any one of the two methods, it can be judged that the anti-loosening design is qualified, and the subsequent steps of outputting the contact surface state can be continued.

[0101] Such as Figure 1As shown, in a feasible implementation, the method for anti-loosening safety check of the tie rod bolt assembled rotor further includes:

[0102] When the result of the finite element calculation does not meet the requirements, perform refined calculation according to the finite element analysis result;

[0103] Obtain the third loosening torque and the third safety factor.

[0104] In this technical solution, since all the numerical values selected during the finite element calculation are conservative values, when the result of the finite element calculation does not meet the requirements, it is necessary to further perform refined calculation according to the finite element analysis result to obtain the third loosening torque and the third safety factor, and then judge whether the anti-loosening design of the contact surface meets the requirements based on the third loosening torque and the third safety factor.

[0105] In a feasible implementation, the steps of performing refined calculation according to the finite element analysis result to obtain the third loosening torque and the third safety factor include:

[0106] Obtain the maximum static friction torque of each element on the contact surface;

[0107] Superimpose the maximum static friction torques of all elements to obtain the third loosening torque;

[0108] Obtain the third safety factor according to the third loosening torque;

[0109] When the third safety factor meets the requirements, output the contact state of the contact surface;

[0110] When the third safety factor does not meet the requirements, the anti-loosening design is unqualified.

[0111] In this technical solution, calculate the maximum static friction torque of each element on the contact surface, superimpose the friction torques of all elements to obtain the third loosening torque of the contact surface, and then calculate the third safety factor according to the third loosening torque. When the third safety factor meets the requirements, it can also represent that the anti-loosening design of the finite element simulation is qualified, and the contact state of the contact surface can be further output; when the third safety factor does not meet the requirements, the anti-loosening design is unqualified and needs to be redesigned.

[0112] Specifically, when the third safety factor is greater than 1, it meets the anti-loosening design requirements.

[0113] In a feasible implementation, the maximum static friction torque of the element is obtained by calculating based on the normal pressure of each node on the contact surface, the node coordinate information, the element information, and the area.

[0114] In this technical solution, first, the maximum static friction torque of each node is calculated based on the positive pressure of each node, then the maximum static friction torque of the unit is calculated based on the maximum static friction torque of the node, and then the maximum static friction torques of the units are superimposed to obtain the maximum static friction torque of the contact surface, that is, the third loosening torque.

[0115] In this technical solution, it is necessary to calculate the maximum static friction torque of each unit on the contact surface, and superimpose the friction torques T of all units i to obtain the anti-loosening torque of the contact surface. First, according to the formula T j = μN j r j calculate the friction torque of node j; assume that unit i has n nodes, and according to the formula calculate the friction torque of this unit as; then assume that there are m units on the contact surface, and according to the formula calculate the loosening torque of the contact surface, that is, the third loosening torque. Finally, according to the formula calculate the third safety factor;

[0116] where, i represents the number of units, j represents the number of nodes, r j represents the radius of node j from the center, and A represents the unit area.

[0117] In a feasible implementation manner, when the contact state of the output friction contact surface is that there is a closed bonded annular region, the anti-loosening design of the contact surface is qualified;

[0118] When the contact state of the output friction contact surface is that there is no closed bonded annular region, the anti-loosening design is unqualified.

[0119] In this technical solution, the contact states in the finite element are divided into away, approaching, bonding, and sliding states. When there is a closed bonded annular region on the contact surface, it is considered that the contact surface has not loosened, and the anti-loosening design of this contact surface is qualified. When the contact surface state is in the away, approaching, bonding, and sliding regions, the anti-loosening design of this contact surface is unqualified and needs to be redesigned.

[0120] Furthermore, when all the annular friction contact surfaces of the rotor meet the above design requirements, the anti-loosening design of the entire rotor is qualified.

[0121] Example:

[0122] The friction contact surfaces between the rotor parts are generally annular surfaces. Assume that the pressure on the annular contact surfaces between the components on the rotor is equivalently uniformly distributed, and the normal pressure on the annular contact surface is only generated by the bolt pre-tightening force of the tie rod. Ignore the influence of the elastic restoring force caused by the axial aerodynamic thrust, centrifugal force, and axial deformation generated by temperature. Solve the loosening torque through the force analysis of the micro-elements. A typical annular contact surface is as Figure 2As shown in the figure. The polar coordinate system is adopted for the solution. First, an arbitrary point P in the plane is taken, and P is represented by the radial coordinate ρ and the circumferential coordinate θ; a differential element PABC of the annular contact surface is taken. The length of OP is ρ, the length of PC is dρ, and the length of PA is ρdθ. Assuming that the normal pressure on the differential element is N, Ti is the loosening torque, μ is the friction coefficient, R is the outer diameter of the contact surface, r is the inner diameter of the contact surface, T 输入 is the input torque, F is the bolt pre-tightening force, S is the safety factor.

[0123] Then the loosening torque of the differential element PABC is: T i = μ·N·ρ·ρ·dθ·dρ.

[0124] Integrate the differential element within the annular contact surface to calculate the loosening moment. The formula is as follows:

[0125]

[0126] Among them,

[0127] Assume that under the action of the tie rod bolt pre-tightening force, the pressure distribution on the annular contact surface between the rotor parts is uniform. At this time, the pressure on the contact surface can be approximately the ratio of the bolt pre-tightening force to the area of the annular contact surface, that is, calculate the safety factor. The formula is as follows:

[0128]

[0129] According to formula (1), calculate the first loosening moment, and then according to the first loosening moment, use formula (2) to calculate the first safety factor as an estimate for the preliminary design. If the first safety factor is greater than 1, it can be considered that the anti-loosening design of the contact surface initially meets the requirements, and finite element simulation calculation is carried out. Otherwise, it needs to be redesigned.

[0130] During actual operation, the rotor is affected by loads such as gravity, centrifugal force, mass eccentricity, local high temperature, and gas flow excitation. The pressure distribution on the annular contact surface between components is non-uniform. The contact area between rotor parts is unknown and changes instantaneously. It is not only determined by the tie rod bolt pre-tightening force, but also related to loads, materials, boundary conditions, and other factors. Further, the finite element method is used to simulate the real operating environment of the rotor. By applying loads such as bolt pre-tightening force, centrifugal force, gravity, temperature, and aerodynamic force, the operating loads of the rotor are comprehensively considered, and the pressure distribution on the contact surface is obtained through finite element solution:

[0131] The pressure distribution on the contact surface obtained by finite element calculation is a non-uniform distribution. First, conservatively equivalent the maximum pressure N on the contact surface max to the average pressure, and calculate the second loosening moment. The formula is as follows:

[0132]

[0133] Then, calculate the second safety factor according to formula (2). If the second safety factor is greater than 1, the anti-loosening design of the contact surface meets the requirements; otherwise, it needs to be redesigned.

[0134] Or,

[0135] Select the maximum positive pressure N on the contact surface max , and calculate the maximum static friction force f per unit area max = μN max . The maximum static friction value represents the torque-bearing capacity at this position. Compare the maximum static friction force with the maximum friction stress output by the finite element calculation, that is, compare the maximum static friction force with the second loosening torque. When the friction stress (second loosening torque) is less than the maximum static friction force, the anti-loosening design requirements are met; otherwise, it needs to be redesigned.

[0136] If both the second safety factor and the maximum static friction force do not meet the requirements, it is necessary to calculate the maximum static friction torque T of each unit on the contact surface i , and add up the friction torques T i of all units to obtain the loosening torque of the contact surface, and then obtain the third loosening torque and the third safety factor:

[0137] Calculate the friction torque of node j, and the formula is as follows:

[0138] T j = μN j r j (4)

[0139] Assume that element i has n nodes, then calculate the friction torque of this element, and the formula is as follows:

[0140]

[0141] Assume that there are m elements on the contact surface, then calculate the third loosening force of the contact surface, and the formula is as follows:

[0142]

[0143] Among them, i represents the number of elements, j represents the number of nodes, and r j represents the radius of node j from the center, and A represents the element area.

[0144] According to the third loosening torque, calculate the third safety factor through formula (2). If the third safety factor is greater than 1, the anti-loosening design of the contact surface meets the requirements; otherwise, it needs to be redesigned. When the third safety factor is greater than 1, output the contact state of the friction contact surface. If there is a closed bonded annular area on the contact surface, it is considered that no loosening has occurred on the contact surface. Calculate all the friction contact surfaces on the rotor according to the above method. When each contact surface meets the above conditions, the anti-loosening design of the entire rotor structure is qualified.

[0145] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above advantageous methods can be freely combined and superimposed.

[0146] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above is only the preferred implementation manner of the present application. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and modifications can be made without departing from the technical principle of the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A method for checking the safety of a pull rod bolt assembly type rotor against loosening, characterized in that: The anti-loosening safety verification method of the pull rod bolt assembled rotor comprises: Obtaining a first loosening torque and a first safety factor of a contact surface on a rotor; Establishing a finite element model of the rotor; Perform finite element calculations; Output the contact status of the contact surface; Wherein, the contact surface is a friction contact surface in the rotor.

2. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 1 is characterized in that: The step of obtaining a first loosening torque and a first safety factor of the contact surface of the rotor comprises: Obtaining the pressure on the contact surface; Take any differential unit on the contact surface; Obtaining the breakaway torque of the differential unit; The differential unit is integrated within the contact surface to obtain the first loosening torque.

3. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 2 is characterized in that: The step of obtaining a first loosening torque and a first safety factor of the contact surface of the rotor further comprises: Obtaining the first safety factor according to the first loosening torque; When the first safety factor meets the requirement, establishing the finite element model; When the first safety factor does not meet the requirement, the anti-loosening design is unqualified.

4. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 1 is characterized in that: The step of establishing the finite element model of the rotor comprises: Building a three-dimensional model according to the structure of the rotor; Setting material parameters of various parts in the rotor; Apply bolt preload, gravity, centrifugal force, temperature, aerodynamic force and other loads and displacement boundary conditions under operating conditions; obtaining the finite element model; In the finite element model, the bolt and the rotating shaft are set to be in binding contact, and the contact surfaces in the rotor are all set to be in friction contact.

5. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 1 is characterized in that: The steps of performing finite element calculation include: The maximum pressure on the contact surface is equivalent to the average pressure to obtain the second loosening torque; Obtaining a second safety factor according to the second loosening torque; When the second safety factor meets the requirement, the contact state of the contact surface is output; When the second safety factor does not meet the requirements, the anti-loosening design is unqualified.

6. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 5 is characterized in that: The step of performing finite element calculation also includes: Select the maximum value of the positive pressure on the contact surface to obtain the maximum static friction force per unit area of ​​the contact surface; When the maximum static friction force per unit area is greater than the maximum friction stress, the contact state of the contact surface is output; When the maximum static friction force per unit area is less than the maximum friction stress, the anti-loosening design is unqualified.

7. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 1 is characterized in that: The anti-loosening safety verification method of the pull rod bolt assembled rotor also includes: When the results of finite element calculation do not meet the requirements, perform detailed calculations based on the finite element analysis results; Obtain the third loosening torque and the third safety factor.

8. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 7 is characterized in that: The step of performing a refined calculation based on the finite element analysis result and obtaining the third loosening torque and the third safety factor comprises: Get the maximum static friction torque of each unit on the contact surface; The maximum static friction torque of all units is superimposed to obtain the third loosening torque; Obtaining the third safety factor according to the third loosening torque; When the third safety factor meets the requirement, outputting the contact state of the contact surface; When the third safety factor does not meet the requirements, the anti-loosening design is unqualified.

9. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 8, characterized in that: The maximum static friction torque of the unit is calculated based on the positive pressure of each node on the contact surface, the node coordinate information, the unit information and the area.

10. The anti-loosening safety verification method of a pull rod bolt assembled rotor according to claim 1, characterized in that: When the contact state of the output friction contact surface is that there is a closed bonding annular area, the anti-loosening design of the contact surface is qualified; When the contact state of the output friction contact surface is such that there is no closed bonding annular area, the anti-loosening design is unqualified.

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