Motor cylindrical roller bearing matching method based on shaft current damage

Abstract

The invention relates to the technical field of bearing machining. The invention discloses a bearing matching method based on shaft current damage, and the method comprises the steps: firstly indicating that the shaft current damage can cause the change of the fractal dimension of a bearing junction surface, thereby affecting the normal contact strength; then analyzing the influence of factors such as the bearing contact state, the normal contact load and the normal contact strength on the bearing performance, and establishing a kinetic model, namely a total contact strength Kcn expression, by integrating the influence; and according to the expression, adjusting the parameters of the roller and the raceway, finally obtaining the bearing meeting the normal total contact strength requirement, and prolonging the service life of the bearing.

Description

Technical Field

[0001] The invention relates to the technical field of bearing processing, and in particular to a method for selecting a motor cylindrical roller bearing based on shaft current damage. Background Art

[0002] Cylindrical roller bearings are important components in modern industries such as industrial machinery and rail transportation. Their failures take various forms, and bearing shaft current damage is one of the main types of motor bearing damage. Bearing shaft current damage is mainly reflected in the plaques produced on the roller and raceway surfaces of the bearing at a macro level. At a micro level, it will also produce many bumps and grooves, which will further increase the wear of the bearing. These damages are mainly caused by the normal force on the raceway and roller. Therefore, it is necessary to improve the normal contact strength of the bearing. However, there are multiple factors that affect the normal contact strength of the bearing, and the factors affect each other, which makes it difficult to improve the normal contact strength of the bearing, which brings difficulties to the selection of bearings. Summary of the invention

[0003] In view of this, it is necessary to provide a bearing selection method based on shaft current damage, so as to improve the normal contact strength of the bearing through the selection of the bearing, thereby increasing the life of the motor bearing.

[0004] A method for selecting a motor cylindrical roller bearing based on shaft current damage comprises the following steps:

[0005] Step S1: Obtain the fractal dimension D of the bearing contact surface damaged by shaft current:

[0006]

[0007] Among them, M(r) is the measure, r is the measurement scale, L(r) is the curve length, and C is the proportionality coefficient;

[0008] Step S2: Obtain the fractal dimension D and surface roughness R of the three-dimensional fractal surface a The relationship between and fractal roughness G, namely

[0009] Fractal dimension D describing the two-dimensional contour l and surface roughness R a The relationship between and fractal roughness G:

[0010]

[0011]

[0012] When the contact surface is isotropic, the fractal dimension of the three-dimensional fractal surface is:

[0013] D=D i +1,

[0014] Where D i The D obtained above can be substituted into l and D j ;

[0015] Step S3: introducing the fractal dimension of the three-dimensional fractal surface into the load calculation;

[0016] The area distribution function k(a) of the ideal microsphere on the roller at the contact point with the bearing raceway and the maximum ideal microsphere contact area a 1 The relationship between them is:

[0017]

[0018] (0<a≤a 1 ,2<D<3);

[0019] Considering the macroscopic contact mode and contact radius between the roller and raceway of a cylindrical roller bearing, the fractal dimension D is introduced into the cylindrical contact coefficient τ c , whose expression is:

[0020]

[0021] Among them, A a is the theoretical contact area; A 1 +A 2 is the contact surface area of ​​the two cylindrical surfaces; χ is the curvature index;

[0022] For cylindrical roller bearings, the actual contact area A between the bearing raceway and the roller is r , elastic critical deformation area a of an ideal microsphere e and the critical plastic deformation area a of an ideal microsphere p The expression is:

[0023]

[0024]

[0025]

[0026] Where a is the actual contact area of ​​the ideal microsphere; k μ is the friction correction coefficient; σ y is the yield strength of the material; γ is the frequency density parameter;

[0027] For the normal contact load of the bearing, when the roller and the inner and outer raceways of the bearing are in the elastic deformation zone, the load is f e (a); The load in the plastic deformation zone is f p (a); The load in the elastic-plastic deformation zone is fep (a), the expressions are:

[0028]

[0029] f p (a) = λσ y a;

[0030]

[0031] Step S4: calculating the normal contact strength of the bearing;

[0032] In the elastic-plastic deformation stage, the total contact load expression of the cylindrical roller bearing with the change of bearing steel hardness with contact depth is given as follows:

[0033]

[0034] According to the definition of normal strength, on the basis of considering the normal contact strength of bearing steel hardness changing with loading depth, the normal total contact strength K considering the elastic-plastic deformation of the ideal microsphere can be obtained. cn The expression is:

[0035]

[0036] Among them, the deformation of the ideal microsphere after loading is:

[0037] ω=2 5.5-1.5D G D-2 (lnγ) 0.5 π 0.5D-1.5 a 1.5-0.5D ;

[0038] Then the normal total contact strength K cn The expression is also:

[0039]

[0040] In the formula,

[0041] When selecting roller bearings, the parameters of the rollers and raceways are adjusted according to the normal total contact strength that the bearings need to meet, and ultimately a bearing that meets the normal total contact strength requirements is obtained.

[0042] Beneficial effects: The present invention first points out that shaft current damage will cause the fractal dimension of the bearing joint surface to change, thereby affecting the normal contact strength. Then, the influence of factors such as bearing contact state, normal contact load and normal contact strength on bearing performance is analyzed, and a dynamic model is established by combining the above-mentioned influences, that is, the total contact strength K cnAccording to this expression, the parameters of the roller and raceway are adjusted to finally obtain a bearing that meets the normal total contact strength requirements and prolongs the bearing service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a simplified model diagram of the contact between the inner ring and the roller of the bearing.

[0044] Figure 2 This is a simplified model diagram of the contact between the bearing outer ring and the roller.

[0045] Figure 3 This is a graph showing the dimensionless normal strength of the inner ring of the bearing before and after shaft current damage versus the actual contact area.

[0046] Figure 4 This is a graph showing the dimensionless normal strength of the bearing outer ring before and after shaft current damage versus the actual contact area.

[0047] Figure 5 This is a graph showing the effect of line contact length on dimensionless normal contact strength.

[0048] Figure 6 This is a graph showing the effect of the equivalent elastic modulus on the dimensionless normal contact strength. DETAILED DESCRIPTION

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0050] Please see Figure 1 The motor cylindrical roller bearing selection method based on shaft current damage includes the following steps:

[0051] Step S1: Obtain the fractal dimension D of the bearing contact surface damaged by shaft current:

[0052]

[0053] Among them, M(r) is the measure, r is the measurement scale, L(r) is the curve length, and C is the proportionality coefficient;

[0054] Step S2: Obtain the fractal dimension D and surface roughness R of the three-dimensional fractal surface a The relationship between and fractal roughness G, namely

[0055] Fractal dimension D describing the two-dimensional contour l and surface roughness R a The relationship between and fractal roughness G:

[0056]

[0057]

[0058] When the contact surface is isotropic, the fractal dimension of the three-dimensional fractal surface is:

[0059] D=D i +1,

[0060] Where D i The D obtained above can be substituted into l and D j ;

[0061] Step S3: introducing the fractal dimension of the three-dimensional fractal surface into the load calculation;

[0062] The area distribution function k(a) of the ideal microsphere on the roller at the contact point with the bearing raceway and the maximum ideal microsphere contact area a 1 The relationship between them is:

[0063]

[0064] (0<a≤a 1 ,2<D<3);

[0065] Considering the macroscopic contact mode and contact radius between the roller and raceway of a cylindrical roller bearing, the fractal dimension D is introduced into the cylindrical contact coefficient τ c , whose expression is:

[0066]

[0067] Among them, A a is the theoretical contact area; A 1 +A 2 is the contact surface area of ​​the two cylindrical surfaces; χ is the curvature index;

[0068] For cylindrical roller bearings, the actual contact area A between the bearing raceway and the roller is r , elastic critical deformation area a of an ideal microsphere e and the critical plastic deformation area a of an ideal microsphere p The expression is:

[0069]

[0070]

[0071]

[0072] Where a is the actual contact area of ​​the ideal microsphere; k μ is the friction correction coefficient, k μ =1-0.228μ;σ y is the yield strength of the material; γ is the frequency density parameter, which is generally taken as 1.5;

[0073] For the normal contact load of the bearing, when the roller and the inner and outer raceways of the bearing are in the elastic deformation zone, the load is f e (a); The load in the plastic deformation zone is f p (a); The load in the elastic-plastic deformation zone is f ep (a), the expressions are:

[0074]

[0075] f p (a) = λσ y a;

[0076]

[0077] Step S4: calculating the normal contact strength of the bearing;

[0078] In the elastic-plastic deformation stage, the total contact load expression of the cylindrical roller bearing with the change of bearing steel hardness with contact depth is given as follows:

[0079]

[0080] According to the definition of normal strength, on the basis of considering the normal contact strength of bearing steel hardness changing with loading depth, the normal total contact strength K considering the elastic-plastic deformation of the ideal microsphere can be obtained. cn The expression is:

[0081]

[0082] Among them, the deformation of the ideal microsphere after loading is:

[0083] ω=2 5.5-1.5D G D-2 (lnγ) 0.5 π 0.5D-1.5 a 1.5-0.5D ;

[0084] Then the normal total contact strength K cn The expression is also:

[0085]

[0086] In the formula,

[0087] When selecting roller bearings, the parameters of the rollers and raceways are adjusted according to the normal total contact strength that the bearings need to meet, and ultimately a bearing that meets the normal total contact strength requirements is obtained.

[0088] The total normal contact strength K cn It can be seen from the expression that in an environment with relatively high requirements for shaft current, by adjusting the relevant parameters in the expression, the bearing can meet the required normal strength requirements.

[0089] In order to facilitate designers to adjust parameters, the present invention analyzes the three main influencing factors of contact mode, line contact length L, and equivalent elastic modulus E on the normal total contact strength.

[0090] Embodiment 1

[0091] The influence of contact mode on the three-dimensional normal strength of cylindrical roller bearings damaged by shaft current is analyzed by using two cases of internal and external contact R 1 The dimensionless normal contact strength of the bearing is calculated under different conditions. The structure and force of the outer ring, roller and inner ring of the bearing are as follows: Figure 1 and Figure 2 As shown. Given parameter D l =2.57, D j =2.11, G = 4.58 × 10 -9 mm, E = 2.1 × 10 5 MPa,γ=1.5,R 2 =3mm, L=5mm, inner contact takes R 1 =23mm, external contact R 1 =17mm.

[0092] The relationship between the bearing normal contact strength under different contact conditions is as follows: Figure 3 and Figure 4 As shown in the figure, it can be seen that the dimensionless normal strength of the inner and outer rings increases with the increase of the dimensionless actual contact area. Shaft current damage reduces the normal contact strength of the inner and outer rings of the bearing. The normal contact strength between the outer ring of the bearing and the roller is greater than the normal contact strength between the inner ring of the bearing and the roller under the same conditions before and after damage. In order to improve the bearing capacity of the bearing, the material strength of the outer ring of the bearing can be optimized first.

[0093] Embodiment 2

[0094] The influence of contact length on the three-dimensional normal strength of cylindrical roller bearings damaged by shaft current is analyzed. Taking the inner contact form of the outer ring of the bearing where corrugated damage often occurs as an example, the dimensionless normal contact strength of the bearing is calculated by different contact lengths L. Given the parameter D l =2.57, D j =2.11, G = 4.58 × 10-9 mm, E = 2.1 × 10 5 MPa,γ=1.5,R 1 =23mm, R 2 =3mm, take L=25mm, 5mm, 1mm for comparative analysis.

[0095] The relationship between the bearing normal contact strength and the contact length is as follows: Figure 5 As shown. Under the condition that the outer ring of the bearing is in contact with the roller, the linear contact length L of the ordinary bearing is reduced, and the dimensionless normal strength K of the bearing cn * The shaft current damages the bearing line contact length L, and the bearing dimensionless normal strength K cn * In order to improve the bearing capacity of the bearing, the length of the roller and the width of the raceway can be appropriately increased.

[0096] Embodiment 3

[0097] The influence of bearing material characteristic parameters on the three-dimensional normal strength of cylindrical roller bearings damaged by shaft current is analyzed. Taking the outer ring of the bearing where corrugated damage often occurs as an example, the contact mode between the bearing roller and the outer raceway is internal contact. The dimensionless normal contact strength of the bearing is calculated by using different equivalent elastic moduli E.

[0098] Given parameter D l =2.57, D j =2.11, G=4.58×10-9mm, γ=1.5, R 1o =23mm, R 1i =17mm, R 2 =3mm, L=5mm. Take E=2.1×105MPa, 1.6×105MPa, 1.1×105MPa respectively.

[0099] Among them, R 1o is the outer circle radius, R 1i is the inner ring radius. The relationship between the bearing normal contact strength under different material characteristic parameters is as follows: Figure 6 As shown in the figure, the equivalent elastic modulus E of the ordinary bearing decreases, and the dimensionless normal strength K of the bearing decreases. cn * The elastic modulus E of the bearing damaged by shaft current decreases, and the dimensionless normal strength of the bearing does not change significantly. Under the same conditions, the normal strength of the ordinary bearing is greater than the normal strength of the bearing damaged by shaft current.

[0100] The present invention can select rollers and outer and inner rings according to the normal contact strength that the bearing needs to withstand. Since the normal contact strength expression has many parameters, simulation calculation is generally required to obtain the final normal contact strength. The results can be referred to Figure 3 to Figure 6 The results in .

[0101] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for selecting motor cylindrical roller bearings based on shaft current damage, characterized in that: The following steps are involved: Step S1: Obtain the fractal dimension D of the bearing contact surface damaged by shaft current: Among them, M(r) is the measure, r is the measurement scale, L(r) is the curve length, and C is the proportionality coefficient; Step S2: Obtain the fractal dimension D and surface roughness R of the three-dimensional fractal surface a The relationship between and fractal roughness G, namely Fractal dimension D describing the two-dimensional contour l and surface roughness R a The relationship between and fractal roughness G: When the contact surface is isotropic, the fractal dimension of the three-dimensional fractal surface is: D=D i +1, Where D i The D obtained above can be substituted into l and D j ; Step S3: introducing the fractal dimension of the three-dimensional fractal surface into the load calculation; The relationship between the area distribution function k(a) of the ideal microsphere on the roller at the contact point with the bearing raceway and the maximum ideal microsphere contact area a1 is: Considering the macroscopic contact mode and contact radius between the roller and raceway of a cylindrical roller bearing, the fractal dimension D is introduced into the cylindrical contact coefficient τ c , whose expression is: Among them, A a is the theoretical contact area; A1+A2 is the contact surface area of ​​the two cylindrical surfaces; χ is the curvature index; For cylindrical roller bearings, the actual contact area A between the bearing raceway and the roller is r , elastic critical deformation area a of an ideal microsphere e and the critical plastic deformation area a of an ideal microsphere p The expression is: Where a is the actual contact area of ​​the ideal microsphere; k μ is the friction correction coefficient; σ y is the yield strength of the material; γ is the frequency density parameter; For the normal contact load of the bearing, when the roller and the inner and outer raceways of the bearing are in the elastic deformation zone, the load is f e (a); The load in the plastic deformation zone is f p (a); The load in the elastic-plastic deformation zone is f ep (a), the expressions are: f p (a)=λσ y a; Step S4: calculating the normal contact strength of the bearing; In the elastic-plastic deformation stage, the total contact load expression of the cylindrical roller bearing with the change of bearing steel hardness with contact depth is given as follows: According to the definition of normal strength, on the basis of considering the normal contact strength of bearing steel hardness changing with loading depth, the normal total contact strength K considering the elastic-plastic deformation of ideal microsphere can be obtained. cn The expression is: Among them, the deformation of the ideal microsphere after loading is: ω=2 5.5-1.5D G D-2 (lnγ) 0.5 p 0.5D-1.5 a 1.5-0.5D ; Then the normal total contact strength K cn The expression is also: In the formula, When selecting roller bearings, the parameters of the rollers and raceways are adjusted according to the normal total contact strength that the bearings need to meet, and ultimately a bearing that meets the normal total contact strength requirements is obtained.

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