Planet carrier pin shaft contact stiffness calculation method considering interference fit and application of planet carrier pin shaft contact stiffness calculation method

Abstract

The invention relates to a planet carrier pin shaft contact rigidity calculation method considering interference fit. The method comprises the following steps: S1, revealing a contact tooth surface rigidity calculation mechanism of two parts in non-hard connection; s2, establishing a planet carrier pin shaft calculation and analysis model based on complex working condition boundary constraint; s3, proposing a penalty function-based planet carrier pin shaft contact stiffness accurate solving method and a data post-processing technology; the problems that interference connection between a planet carrier and a pin shaft is processed into hard binding through existing gear transmission system analysis software, the rigidity of the contact face is far larger than the actual interference rigidity, the calculation error of the comprehensive dislocation amount of a planetary gear train is large, and correct design of a tooth face cannot be guided are solved. According to the calculation method, the contact rigidity of the pin shaft and the planet carrier under interference fit can be accurately solved, accurate input is provided for calculation of the comprehensive dislocation amount of a planetary gear train, and the rigidity between any non-hard-connected assembly components can be solved.

Description

Technical Field

[0001] The present invention belongs to the field of gear drive systems for major equipment, and relates to a calculation method and application of the contact stiffness of the pin shaft of a planet carrier considering interference fit, in particular to an accurate solution method for the contact stiffness of the pin shaft of a planet carrier considering interference fit and the application of the accurate solution method for the contact stiffness of the pin shaft of the planet carrier. Background Art

[0002] With the rapid economic growth, the demand for energy and electricity is constantly rising. Wind power generation has become an important starting point for China to promote energy transformation. As the core component of major equipment in the wind power field, the meshing quality of the wind power gear drive chain directly determines the service performance of the whole machine. With the continuous increase of the MW level of wind turbines (exceeding 20 MW), new challenges have been posed to the design method of the planetary gear train of wind power gearboxes.

[0003] In the existing design process of the planetary gear train of gearboxes, there is a relatively high dependence on commercial software such as Romax / Kisssoft. The stiffness between the pin shaft and the planet carrier usually adopts a rigid binding connection RBE2 / RBE3, and the stiffness of its contact surface is much greater than the actual interference stiffness (the rigid binding stiffness is order of magnitude, and usually the interference fit stiffness is in order of magnitude), resulting in a large deviation between the simulation calculation results of the deformation of the planet carrier and the misalignment of gear meshing and the actual situation, which cannot correctly guide the design, and causing problems such as low-quality meshing of the sun gear, planet gear, and ring gear of the planetary gear train and "overhanging" in the contact area, directly affecting the service performance of the whole wind power gearbox. Therefore, there is an urgent need to propose an accurate solution method for the contact stiffness of the pin shaft of the planet carrier to solve the problem of the simplified treatment of the rigid binding of interference connectors by existing commercial design software.

[0004] During the accurate solution process of the contact stiffness of the pin shaft of the planet carrier, the following technical problems exist: 1) The actual working conditions between the pin shaft and the planet carrier are complex and changeable, it is difficult to model the composite model of the pin shaft of the planet carrier, and the stiffness solution mechanism considering interference connection is missing; 2) The boundary conditions and load arrangement methods of the pin shaft drive system of the planet carrier based on the actual service conditions are missing, and after accurate solution, the deformation amount extraction of the system model and the data post-processing technology are lacking. Summary of the Invention

[0005] In view of this, in order to solve the problem that the existing gear drive system analysis software treats the interference connection between the planet carrier and the pin shaft as a rigid binding (RBE2 / RBE3), and the stiffness of its contact surface is much greater than the actual interference stiffness, resulting in a large calculation error of the comprehensive misalignment of the planetary gear train and being unable to guide the correct design of the tooth surface, the present invention provides a calculation method and application of the contact stiffness of the pin shaft of the planet carrier considering interference fit.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A calculation method for the contact stiffness of the planet carrier pin shaft considering interference fit, comprising the following steps:

[0008] S1. Reveal the contact tooth surface stiffness calculation mechanism of two non-rigidly connected components;

[0009] The contact stiffness of two non-rigidly connected components is, under the same force condition, the ratio of the difference between the force in any direction and the linear displacement amount of the planet carrier and the pin shaft with different displacement amounts in each direction, which is the support stiffness in that direction; the ratio of the difference between the torque in any direction and the angular displacement amount is the torsional stiffness in that direction;

[0010] S2. Establish a calculation and analysis model of the planet carrier pin shaft based on the boundary constraints under complex working conditions;

[0011] Based on the design parameters of the planet carrier and the pin shaft, construct a three-dimensional solid model of the transmission system, remove the parts that affect the calculation efficiency, determine the load boundary of the planet carrier pin shaft based on the actual service conditions of the transmission system, geometrically divide the pin shaft and set different boundary loads on the corresponding parts, and establish an efficient calculation model of the planet carrier - pin shaft based on central symmetry;

[0012] S3. Propose an accurate solution method for the contact stiffness of the planet carrier pin shaft based on the penalty function and data post-processing technology;

[0013] The interference amount between the pin shaft and the planet carrier is added through the penalty function. Among them, the friction coefficient is selected based on the material, and the model is analyzed by finite element method to obtain the calculation results; extract the displacements and rotations in the X / Y / Z three directions of the reference points on both sides of the front and rear ends of the pin shaft, as well as the forces and torques on the reference points, and accurately calculate the support stiffness and torsional stiffness of the two contacting parts under interference fit according to the mechanism in step S1.

[0014] Furthermore, the calculation formulas for the support / torsional stiffness of the planet carrier and the pin shaft in the X, Y, and Z three directions in step S1 are:

[0015]

[0016] In the formula, , and respectively represent the support forces in the three directions of the contact surface, , and respectively represent the torques in the three directions of the contact surface, , and respectively represent the linear displacements in the three directions of the contact surface, , and respectively represent the angular displacements in the three directions of the contact surface.

[0017] Furthermore, in step S2, the precise solid model is imported into the 3D modeling software, and the holes, chamfers, and rib plate parts that affect the calculation efficiency in the three-dimensional models of the planet carrier and the pin shaft are removed to improve the finite element simulation efficiency.

[0018] Furthermore, in step S2, the pin shaft is divided into four parts, and different boundary loads are added based on the actual service conditions, namely the axial force and the radial force of the planet gear on the pin shaft.

[0019] Furthermore, in order to improve the calculation efficiency in step S2, the planet carrier is cut according to the number of planet gears, symmetric constraints are added on both sides of the cut surface, and fixed constraints and torques are added at the end of the planet carrier to simulate the actual service conditions.

[0020] Furthermore, in step S3, the precise solution of the contact stiffness between the pin shaft and the planet carrier is achieved by adding a penalty function, setting the friction coefficient of the contact surface, constructing a finite element calculation model and performing simulation analysis. When extracting the calculation results, it is necessary to extract and numerically sum the linear displacements and torsional displacements in the X, Y, and Z directions of all grid nodes on the contact surface as the total displacement of the contact surface; the support forces and torques in the X, Y, and Z directions of each grid node are also numerically summed as the total force on the contact surface.

[0021] The calculation method for the contact stiffness of the planet carrier pin shaft considering interference fit is used to solve the stiffness between any non-rigidly connected assembly components. By calculating the difference in displacement / torsion amount through the loading of the actual contact situation, the connection stiffness between the two components is solved.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The calculation method for the contact stiffness of the planet carrier pin shaft considering interference fit disclosed by the present invention reveals the stiffness solution mechanism of the pin shaft and the planet carrier in the case of interference connection, and proposes that under the same working conditions, the displacement / torsion of the planet carrier and the pin shaft are different, and the ratio of the force in any direction to the difference in its displacement / torsion amount is the support / torsion stiffness in that direction. This mechanism can not only solve the problem of rough design parameters caused by the hard binding assumption in the traditional stiffness method, but also be extended and applied to other non-hard binding scenarios, and solve the connection stiffness between the two components by calculating the difference in displacement / torsion amount through the loading of the actual contact situation.

[0024] 2. The method for calculating the contact stiffness of the planet carrier pin considering interference fit disclosed by the present invention determines the load boundary of the planet carrier pin based on the actual service conditions of the transmission system, geometrically divides the pin and sets different boundary loads on the corresponding parts, and establishes an efficient calculation model of the planet carrier - pin based on central symmetry, which can accurately simulate the true service stress state of the planet carrier and the pin; and based on the finite element model, a method for quickly extracting the displacement and torque loads is proposed to realize the solution and rapid extraction of the contact force and moment of the pin and the planet carrier. The contact stiffness calculated based on this, and the verified comprehensive misalignment of the system is close to the actual misalignment of the system.

[0025] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. Brief Description of the Drawings

[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0027] Figure 1 is the flow chart of the method for calculating the contact stiffness of the planet carrier pin considering interference fit of the present invention;

[0028] Figure 2 For the present invention Figure 1 is the schematic diagram of the constraint boundary of the pin - planet carrier system in step S2 of the present invention;

[0029] Figure 3 For the present invention Figure 1 is the schematic diagram of the load addition of the pin - planet carrier system in step S2 of the present invention;

[0030] Figure 4 For the present invention Figure 1 is the schematic diagram of the finite element mesh division of the pin - planet carrier system in step S3 of the present invention. Detailed Embodiments

[0031] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0032] As Figure 1 shown, a method for calculating the contact stiffness of the planet carrier pin considering interference fit includes the following steps:

[0033] S1. Reveal the mechanism of the contact tooth surface stiffness of two non-rigidly connected components;

[0034] The contact stiffness of two non-rigidly connected components can be understood as the ratio of the difference between the force in any direction and its linear displacement to the linear displacement of the planet carrier and the pin shaft under the same force condition, which is the support stiffness in that direction; the ratio of the difference between the torque in any direction and its angular displacement is the torsional stiffness in that direction.

[0035] Furthermore, derive the calculation formulas for the support / torsional stiffness of the planet carrier and the pin shaft in the X, Y, and Z directions, as follows:

[0036]

[0037] In the formula, , and respectively represent the support forces in the three directions of the contact surface, , and respectively represent the torques in the three directions of the contact surface, , and respectively represent the linear displacements in the three directions of the contact surface, , and respectively represent the angular displacements in the three directions of the contact surface.

[0038] S2. Establish a calculation and analysis model of the planet carrier pin based on the boundary constraints under complex working conditions;

[0039] Based on the design parameters of the planet carrier and the pin shaft, construct a three-dimensional solid model of the transmission system, and remove parts that affect the calculation efficiency such as holes, chamfers, and rib plates. Determine the load boundary of the planet carrier pin based on the actual service conditions of the transmission system, geometrically divide the pin shaft and set different boundary loads on the corresponding parts to establish an efficient calculation model of the planet carrier - pin shaft based on central symmetry.

[0040] Figure 2 Among them, the number of planet gears in the planet carrier is 3. To save calculation time and improve calculation efficiency, only one pair of the planet carrier and the pin shaft is calculated, that is, 1 / 3. Therefore, it is necessary to add symmetric boundary constraints. The interference fit between the pin shaft and the planet carrier is added through the penalty function, and the friction coefficient is selected as 0.2; a rotary boundary coupling is added to the front end of the planet carrier for easy addition of torque; an elastic locking unit is added to the rear end for better simulation of the constraint of the planet shaft fixed on the bearing.

[0041] Figure 3Apply torque, and note that only 1 / 3 of the actual service condition value is applied. The rear end is fixed in the Z direction. Since there is no stiffness reference for the torsion of the bearing in the Z direction according to the known values, it is set to be fixed in the Z direction. The pin shaft is subject to three forces: the tangential force of the pin shaft, which is caused by the pin shaft bearing, and the axial forces at the front and rear ends are a pair of forces with equal magnitudes and opposite directions. The front end is the axial force generated by the meshing of the planet gear and the sun gear, and the rear end is the axial force generated by the meshing of the planet gear and the ring gear.

[0042] S3. Propose an accurate solution method for the contact stiffness of the planet carrier pin shaft based on the penalty function and data post-processing technology;

[0043] The interference amount between the pin shaft and the planet carrier is added through the penalty function. Among them, the friction coefficient is selected based on the material, and the model is analyzed by finite element analysis to obtain the calculation results; extract the displacements and rotations in the X / Y / Z three directions of the reference points on both sides of the front and rear ends of the pin shaft, as well as the forces and torques of the reference points. According to the mechanism in step S1, the support stiffness and torsional stiffness of the two contacting parts under the interference fit can be accurately calculated.

[0044] Figure 4 Figure [ID number] is a schematic diagram of the finite element mesh division of the pin shaft planet carrier system. To ensure accurate calculation of the contact surface, hexahedral meshes are used for fine division and submitted to the finite element analysis software for calculation. To ensure the accuracy of the calculation, post-processing of the calculation results is required. When extracting the calculation results, it is necessary to extract and numerically sum the linear displacements and torsional displacements in the X, Y, and Z directions of all mesh nodes on the contact surface as the total displacement of the contact surface; the support forces and torques in the X, Y, and Z directions of each mesh node are also numerically summed as the total force on the contact surface.

[0045] This method is based on finite element analysis technology, which can accurately calculate the support stiffness and torsional stiffness of the contact surface between the planet carrier and the pin shaft for the actual service conditions, getting rid of the strong dependence on commercial software such as Romax / Kisssoft in the design process of the existing planetary gear train of the gearbox, and solving the problem that the stiffness between the pin shaft and the planet carrier in the existing commercial software usually uses a hard-bound connection, resulting in a large deviation between the system comprehensive misalignment amount and the actual situation and being unable to correctly guide the design.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A calculation method for the contact stiffness of the planet carrier pin shaft considering interference fit, characterized in that It includes the following steps: S1. Reveal the mechanism of the contact tooth surface stiffness of two non-rigidly connected components; The contact stiffness of two non-rigidly connected components is, under the same force condition, the ratio of the difference between the displacements of the planet carrier and the pin in any direction to the linear displacement amount in that direction, which is the support stiffness in that direction; The ratio of the difference between the torque in any direction and the angular displacement amount in that direction is the torsional stiffness in that direction; S2. Establish a calculation and analysis model of the planet carrier pin based on the boundary constraints under complex working conditions; Based on the design parameters of the planet carrier and the pin, construct a three-dimensional solid model of the transmission system, remove the parts that affect the calculation efficiency, determine the load boundary of the planet carrier pin based on the actual service conditions of the transmission system, geometrically divide the pin and set different boundary loads on the corresponding parts, and establish an efficient calculation model of the planet carrier - pin based on central symmetry; S3. Propose an accurate solution method for the contact stiffness of the planet carrier pin based on the penalty function and data post-processing technology; The interference amount between the pin and the planet carrier is added through the penalty function. Among them, the friction coefficient is selected based on the material. Conduct a finite element analysis on the calculation model established in step S2 and obtain the calculation results; extract the displacements and rotations in the X / Y / Z three directions of the reference points on both sides of the front and rear ends of the pin, as well as the forces and torques on the reference points. According to the mechanism in step S1, accurately calculate the support stiffness and torsional stiffness of the two contacting parts under interference fit.

2. The planetary carrier pin shaft contact stiffness calculation method according to claim 1, characterized in that The calculation formulas for the support / torsional stiffness of the planet carrier and the pin in the X, Y, and Z directions in step S1 are: Wherein, , and respectively represent the supporting forces in three directions of the contact surface, , and respectively represent the torques in three directions of the contact surface, , and respectively represent the linear displacements in three directions of the contact surface, , and respectively represent the angular displacements in three directions of the contact surface.

3. The planetary carrier pin contact stiffness calculation method according to claim 1, characterized in that In step S2, import the accurate solid model into the three-dimensional modeling software, remove the holes, chamfers, and rib plates in the three-dimensional models of the planet carrier and the pin that affect the calculation efficiency, and improve the finite element simulation efficiency.

4. The planetary carrier pin contact stiffness calculation method according to claim 3, characterized in that In step S2, divide the pin into four parts and, based on the actual service conditions, add different boundary loads: namely, the axial force and radial force of the planet gear on the pin respectively.

5. The planetary carrier pin contact stiffness calculation method according to claim 4, wherein, In step S2, to improve the calculation efficiency, cut the planet carrier according to the number of planet gears, add symmetric constraints on both sides of the cut surface, add fixed constraints and torque at the end of the planet carrier, and simulate the actual service conditions.

6. The method for calculating the contact stiffness of the planet carrier pin shaft according to claim 1, characterized in that, In step S3, the accurate solution of the contact stiffness between the pin and the planet carrier is achieved by adding a penalty function, setting the friction coefficient of the contact surface, constructing a finite element calculation model and conducting a simulation analysis; when extracting the calculation results, extract and numerically sum the linear displacements and torsional displacements in the X / Y / Z three directions of all grid nodes on the contact surface as the total displacement of the contact surface; also numerically sum the support forces and torques in the X / Y / Z three directions of each grid node as the total force on the contact surface.

7. Application of the planetary carrier pin contact stiffness calculation method according to any one of claims 1 to 6, characterized in that This contact stiffness calculation method is used to solve the stiffness between any non-rigidly connected assembly components. By calculating the difference in displacement / torsion amount under the loading of the actual contact situation, the connection stiffness between the two components is solved.

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