CN115408839A - Large-scale tunneling machine main drive bearing service life assessment method and computer readable medium - Google Patents

Abstract

The invention belongs to the field of service life prediction of main bearings, and provides a service life evaluation method of a main drive bearing of a large-scale tunneling machine and a computer readable medium. The method is provided based on bearing load distribution and an l-p service life theory, aiming at the problems that the main drive bearing causes inner ring deformation, uneven stress distribution of rollers and difficult prediction of the service life of a main bearing under the action of axial force, radial force and overturning moment. Bearing load distribution is considered, a stress balance equation of three rows of roller bearings is established based on a Hertz contact theory according to the bearing condition of a main driving shaft of the large-sized excavator, and MATLAB is utilized to develop a main bearing load distribution solving program, so that the service life of a main bearing is evaluated. The method can quickly and efficiently calculate the fatigue life of the main driving bearing of the large-scale tunneling machine, and greatly reduces large-scale personal property loss caused by fatigue failure of the main driving bearing.

Description

A method for evaluating the life of a main drive bearing of a large-scale roadheader and a computer-readable medium

technical field

The invention relates to the field of main bearing life prediction, in particular to a method for evaluating the life of a main drive bearing of a large roadheader and a computer-readable medium.

Background technique

Accurately predicting the fatigue life of the main drive bearing of a large roadheader can prevent large-scale engineering accidents caused by bearing fatigue failure and minimize the loss of life and property. Bearing life prediction is the most critical part of bearing design, and often requires a lot of manpower and material resources. In 1947, Lundberg and Palmgren proposed an exponential equation for bearing fatigue relief, that is, the L-P theoretical life model. Many scholars have revised the model, and the ISO standard method formed by the International Organization for Standardization to simplify and revise the L-P theory is widely used at present. This standard considers that the bearing load is evenly distributed and is suitable for small bearings with simple forces. The size of the main drive bearing of a large roadheader is relatively large, and the load it bears is relatively complex, and the calculation error with a uniform load is relatively large. Both the L-P theory and the ISO standard method can only calculate the reference rating life of the bearing under normal load conditions, that is, through the actual load conditions of the bearing, an average radial load and axial load are obtained, and then the bearing life is calculated. This method is only suitable for small bearings with simple working conditions and uniform bearing load distribution. The real bearing life cannot be reflected when estimating the fatigue life of the main thrust bearing of a large roadheader under complex load conditions.

At present, the life prediction method based on the mechanical model is mainly based on the damage mechanics method. The damage mechanics method studies the evolution and development of damage with deformation until failure of materials under load. During the fatigue test, Wholer summarized the fatigue resistance curve (S-N curve) through a large number of experiments, revealing the influence of cyclic stress on the fatigue life. American scholars proposed the current cumulative formula on the basis of Miner and Palmagren, forming the Palmgren-Maliner cumulative damage criterion. It will be continuously supplemented later, and the damage degree of the material will be described by defining the "damage variable". When the accumulation of fatigue damage D reaches the threshold value, the material is considered to be damaged. The damage mechanics method establishes the damage evolution equation related to the stress and the stress cycle, and the fatigue life of the material can be calculated through the damage stress. Damage stress requires complex finite element analysis. The main drive bearing of a large roadheader has a large size and complex structure, so it is difficult and time-consuming to perform finite element analysis.

Therefore, it is particularly important to propose a life evaluation method for main drive bearings of large roadheaders, and it is particularly important to calculate the fatigue life of main bearings based on the load distribution of main bearings in consideration of actual working conditions. Use MATLAB to build the main bearing fatigue life calculation system to simplify the calculation process of the main bearing fatigue life. You only need to input the necessary parameters of the main bearing and the load of each working condition of the main bearing to get the fatigue life of the main bearing. The operation is simple and the calculation is efficient.

Contents of the invention

The purpose of the present invention is to provide a method for evaluating the life of a main drive bearing of a large roadheader and a computer-readable medium. This method can quickly and efficiently calculate the fatigue life of the main bearing. Aiming at the problem that the inner ring of the main bearing is deformed and the force distribution of the rollers is uneven under the action of the axial force, radial force and overturning moment, resulting in the difficulty of predicting the life of the main bearing, the lubrication is considered based on the bearing load distribution and l-p life theory A method for evaluating the life of main drive bearings of large roadheaders is proposed. This method considers the load distribution of the main drive bearings, and according to the stress on the three-row roller bearings of the main drive of the large-scale roadheader, the force balance equation of the three-row roller bearings is established by Hertz theory, and the main bearing load distribution solution program is developed by using MATLAB. The l-p formula considers the influence of lubrication and other factors to evaluate the service life of the main bearing. The main bearing life evaluation system is built on the MATLAB APP to simplify the calculation process of the main bearing fatigue life, and the calculation is fast and efficient.

Technical scheme of the present invention is as follows:

A method for evaluating the life of the main drive bearing of a large-scale roadheader, which determines the structural parameters of the main drive bearing; according to the stress on the main drive bearing, the force balance equation of the three-row roller main drive bearing is established by Hertz theory, and the load distribution of the main drive bearing is obtained; The equivalent dynamic load of the main drive bearing is calculated according to the load distribution of the main drive bearing. Based on the L-P life theory, the service life of the main drive bearing is obtained by considering the life correction factor; the specific steps are as follows:

S1. Determine the structural parameters of the main drive bearing

Main drive bearing structure includes main thrust roller 1, radial roller 2, thrust roller 3, inner ring gear 4, first outer ring 5, second outer ring 6 and third outer ring 7; main drive bearing structural parameters Including the number of main thrust rollers Z _u , the number of thrust rollers Z _o , the number of radial rollers Z _j , the effective length of main thrust rollers L _wu , the effective length of thrust rollers L _wo , the effective length of radial rollers L _wj , Main thrust roller diameter D _wu , thrust roller diameter D _wo , radial roller diameter D _wj , main thrust roller pitch circle diameter d _u and thrust roller pitch circle diameter d _o ;

S2. According to the force characteristics of the main drive bearing, determine the load distribution of the main drive bearing. The load includes axial force Fa, radial force Fr, overturning moment M and speed V. The outer ring of the main drive bearing is fixed on the nose frame. Under the action of axial force, radial force and overturning moment, the inner ring of the main drive bearing produces displacement and inclination (as shown in Figure 2); the axial displacement δ _a , radial displacement δ _r and inclination θ of the main drive bearing are established based on Hertz theory Balance equation with main drive bearing load;

S2.1 Take the axis of the main drive bearing as the origin, establish a polar coordinate system, the direction of the radial force is the direction of the polar axis, and the position of the roller is represented by the polar angle ψ of the roller;

In the formula: i is the roller serial number, and i=1～Z _k ; k=u, o, j;

The displacement and inclination of the inner ring gear of the main drive bearing lead to changes in the normal distance between the two raceways where the rollers contact, and the rollers bear different loads at different positions;

S2.2 The normal approach value _δψu at the location of the main thrust roller is shown in formula 2), and the bearing load Q _ψu of the main thrust roller is shown in formula 3);

In the formula: P _a is the axial clearance of the main bearing; K _u is the "load-deformation" constant of the main thrust roller and raceway;

In the formula: D _w is the diameter of the roller; η is the comprehensive elastic constant; m is the ratio of the diameter of the roller to the diameter of the pitch circle, when m<0.2, m is ignored;

S2.3 At each thrust roller position ψ, the normal approach value _δψo between the two raceway surfaces is:

The load Q _ψo on the thrust roller at any position ψ is:

In the formula, K _d is the "load-deformation" constant of the thrust roller and the raceway;

S2.4. After the radial displacement δ _r of the inner ring gear of the main drive bearing, the normal approach value δ _ψj between the two raceway surfaces in contact with the radial rollers at different positions ψ is:

In the formula, P _r is the radial clearance of the main drive bearing;

The radial roller bearing load Q _ψj at any position ψ is:

In the formula, K _j is the "load-deformation" constant of the radial roller and the raceway;

S2.5 Establish the balance equation of the main drive bearing based on the Hertzian contact theory and the deformation coordination equation;

S2.6 Substitute formulas 1)-10) into the balance equation 11) of the main drive bearing, and use Newton iterative method to solve the unknown variables main drive bearing axial displacement δ _a , radial displacement δ _r and inclination θ based on MATALAB. After the solution is completed, further Calculate the bearing load Q _ψu of the main thrust roller, Q _ψo of the thrust roller and Q _ψj of the radial roller;

S3 calculates the equivalent dynamic load of the main drive bearing according to the load distribution of the main drive bearing, and obtains the basic service life of the main drive bearing by combining the rated dynamic load _Qc of the main drive bearing and the correction factor α of the service life of the bearing. The steps are as follows:

S3.1 The main thrust roller of the main drive bearing bears the main axial force and overturning moment, and the main thrust raceway of the main drive bearing has the greatest possibility of fatigue failure; fatigue failure occurs at any position of the main drive bearing, that is, the fatigue life of the main drive bearing is reached;

The equivalent dynamic load Q _e of the main bearing is calculated through the bearing load Q _ψu of the main thrust roller

In the formula: λ is the reduction factor caused by the edge stress and non-uniform stress distribution of the main propulsion roller, which is taken as 0.6-0.8; γ is D _wu cosα/d _u ;

In the formula: κ is the viscosity ratio of lubricating oil, e _c is the pollution coefficient, which is 0.8-1.0, and C _u is the fatigue load limit of the main drive bearing;

C ₀ is the basic rated static load;

S3.2 Based on the L-P life theory, consider the viscosity ratio of lubricating oil and the fatigue load limit of the main drive bearing and add the life correction factor of the main drive bearing to obtain the service life of the main bearing; the service life L of the main drive bearing is in millions of revolutions:

Main drive bearing working time T, unit is hour:

A computer-readable storage medium, equipped with a main bearing life evaluation system, the main bearing life evaluation system implements the method described in claim 1 when executed, and the main bearing is obtained after the system interface inputs the main bearing load spectrum and bearing structural parameters service life.

The main bearing life evaluation system includes the input of main drive bearing operating conditions, the input of main bearing structural parameters, the calculation of main bearing load distribution, and the evaluation of main bearing fatigue life; the specific steps of the main bearing life evaluation system are as follows:

Step 1. Establish a life evaluation system for the main drive bearing of a large-scale roadheader, and input the structural parameters of the main drive bearing of a large-scale roadheader;

Step 2. Input the actual working condition of the main bearing according to the actual working condition of the large roadheader;

Step 3. Calculate the load distribution of the main bearing according to the Hertz contact theory and the deformation coordination equation,

Step 4. According to the load distribution of the main bearing, the program of the main drive bearing life evaluation system of the large roadheader is called to calculate the rated life of the main bearing.

Beneficial effects of the present invention: Aiming at the problem that the inner ring of the main bearing is deformed and the force distribution of the rollers is uneven under the action of axial force, radial force and overturning moment, which leads to the difficulty in predicting the service life of the main bearing, based on the bearing load distribution Combined with the l-p life theory to realize the life evaluation of main drive bearings of large-scale roadheaders; this method can quickly and efficiently calculate the fatigue life of main bearings of large-scale roadheaders, and greatly reduce the large-scale personal and property losses caused by fatigue failure of main bearings.

Description of drawings

Fig. 1 is a structural schematic diagram of a three-row roller main drive bearing in the present invention;

Fig. 2 is a schematic diagram of the force on the main drive bearing in the present invention.

In the figure: 1-main thrust roller, 2-radial roller, 3-thrust roller, 4-internal ring gear, 5-first outer ring, 6-second outer ring, 7-third outer ring.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1, the main drive bearing structure includes the main thrust roller 1, the radial roller 2, the thrust roller 3, the inner ring gear 4, the first outer ring 5, the second outer ring 6 and the third outer ring 7 According to Figure 2, it can be seen that the outer ring of the driving bearing is fixed on the head frame, and the inner ring of the main driving bearing produces displacement and inclination under the action of axial force, radial force and overturning moment.

A computer-readable storage medium stores a main bearing life evaluation system, and the main bearing life evaluation system is executed by a processor to realize the evaluation method. The computer-readable storage medium may be any available medium that can be accessed by a computer, or a data storage device such as a server or a data center integrated with one or more available media. The life evaluation system of the main bearing, through the input of the structural parameters of the main drive bearing of the large-scale roadheader, and the actual working condition of the main drive bearing according to the actual working state of the large-scale roadheader. The load distribution of the main drive bearing is calculated according to the Hertz contact theory and the deformation coordination equation, and the rated life of the main bearing is calculated by calling the background program according to the load distribution of the main drive bearing.

Example 1

Taking the actual working condition of a TBM as an example, the main drive bearing of the TBM is a three-row cylindrical roller bearing. The working bid section is mainly composed of Variscan granite interbedded with biotite granite, accounting for 99.22%, and the rock mass is complete and stable.

Step 1: Determine the main drive bearing load as axial force 19206kN, radial force 1804kN, overturning moment 4177kN*m.

Step 2: Determine the basic parameters of the main drive bearing, the center distance of the main thrust rollers is 4338mm, the diameter of the main thrust rollers is 100mm, the effective parameter of the main thrust rollers is 94mm, and the number of main thrust rollers is 104.

Step 3: Fill in the relevant information on the main drive bearing life evaluation platform of the large roadheader, and calculate the fatigue life of the main drive bearing.

Step 4: Click Calculate Corrected Life to check the working time of the main drive bearing.

Claims (3)

1. A method for evaluating the life of a main drive bearing of a large roadheader, characterized in that the structural parameters of the main drive bearing are determined; according to the stressed situation of the main drive bearing, the force balance equation of the three-row roller main drive bearing is established by Hertz theory, and obtained Load distribution of the main drive bearing; calculate the equivalent dynamic load of the main drive bearing based on the load distribution of the main drive bearing, based on the L-P life theory, and consider the life correction factor to obtain the service life of the main drive bearing; the specific steps are as follows: S1. Determine the structural parameters of the main drive bearing Main drive bearing structure includes main thrust roller (1), radial roller (2), thrust roller (3), inner ring gear (4), first outer ring (5), second outer ring (6) and the third outer ring (7); the structural parameters of the main drive bearing include the number of main thrust rollers Z _u , the number of thrust rollers Z _o , the number of radial rollers Z _j , the effective length of main thrust rollers L _wu , the number of thrust rollers Effective length L _wo , radial roller effective length L _wj , main thrust roller diameter D _wu , thrust roller diameter D _wo , radial roller diameter D _wj , main thrust roller pitch circle diameter _du and thrust roller The pitch circle diameter d _o of the child; S2. According to the force characteristics of the main drive bearing, determine the load distribution of the main drive bearing. The load includes axial force Fa, radial force Fr, overturning moment M and rotational speed V; based on the Hertz theory, establish the axial displacement δ _{a of} the main drive bearing, Balance equation of radial displacement _δr and inclination θ with main drive bearing load; S2.1 Take the axis of the main drive bearing as the origin, establish a polar coordinate system, the direction of the radial force is the direction of the polar axis, and the position of the roller is represented by the polar angle ψ of the roller;

In the formula: i is the roller serial number, and i=1～Z _k ; k=u, o, j; The displacement and inclination of the inner ring gear of the main drive bearing lead to changes in the normal distance between the two raceways where the rollers contact, and the rollers bear different loads at different positions; S2.2 The normal approach value _δψu at the location of the main thrust roller is shown in formula 2), and the bearing load Q _ψu of the main thrust roller is shown in formula 3);

In the formula: P _a is the axial clearance of the main bearing; K _u is the "load-deformation" constant of the main thrust roller and raceway;

In the formula: D _w is the diameter of the roller; η is the comprehensive elastic constant; m is the ratio of the diameter of the roller to the diameter of the pitch circle, when m<0.2, m is ignored; S2.3 At each thrust roller position ψ, the normal approach value _δψo between the two raceway surfaces is:

The load Q _ψo on the thrust roller at any position ψ is:

In the formula, K _d is the "load-deformation" constant of the thrust roller and the raceway;

S2.4. After the radial displacement δ _r of the inner ring gear of the main drive bearing, the normal approach value δ _ψj between the two raceway surfaces in contact with the radial rollers at different positions ψ is:

In the formula, P _r is the radial clearance of the main drive bearing; The radial roller bearing load Q _ψj at any position ψ is:

In the formula, K _j is the "load-deformation" constant of the radial roller and the raceway;

S2.5 Establish the balance equation of the main drive bearing based on the Hertzian contact theory and the deformation coordination equation;

S2.6 Substitute formulas 1)-10) into the balance equation 11) of the main drive bearing, and use Newton iterative method to solve the unknown variables main drive bearing axial displacement δ _a , radial displacement δ _r and inclination θ based on MATALAB. After the solution is completed, further Calculate the bearing load Q _ψu of the main thrust roller, Q _ψo of the thrust roller and Q _ψj of the radial roller; S3 calculates the equivalent dynamic load of the main drive bearing according to the load distribution of the main drive bearing, and obtains the basic service life of the main drive bearing by combining the rated dynamic load _Qc of the main drive bearing and the correction factor α of the service life of the bearing. The steps are as follows: S3.1 The main thrust roller of the main drive bearing bears the main axial force and overturning moment, and the main thrust raceway of the main drive bearing has the greatest possibility of fatigue failure; fatigue failure occurs at any position of the main drive bearing, that is, the fatigue life of the main drive bearing is reached; The equivalent dynamic load Q _e of the main bearing is calculated through the bearing load Q _ψu of the main thrust roller

In the formula: λ is the reduction factor caused by the edge stress and non-uniform stress distribution of the main propulsion roller, which is taken as 0.6-0.8; γ is D _wu cosα/d _u ;

In the formula: κ is the viscosity ratio of lubricating oil, e _c is the pollution coefficient, which is 0.8-1.0, and C _u is the fatigue load limit of the main drive bearing;

C ₀ is the basic rated static load;

S3.2 Based on the L-P life theory, consider the viscosity ratio of lubricating oil and the fatigue load limit of the main drive bearing and add the life correction factor of the main drive bearing to obtain the service life of the main bearing; the service life L of the main drive bearing is in millions of revolutions:

Main drive bearing working time T, unit is hour:

2. A computer-readable storage medium, characterized in that it is equipped with a main bearing life evaluation system, the method described in claim 1 is implemented when the main bearing life evaluation system is executed, and the system interface inputs the main bearing load spectrum and bearing structure After the parameters are obtained, the service life of the main bearing is obtained. 3. The computer-readable storage medium according to claim 2, wherein the specific steps of the main bearing life evaluation system are as follows: Step 1. Establish a life evaluation system for the main drive bearing of a large-scale roadheader, and input the structural parameters of the main drive bearing of a large-scale roadheader; Step 2. Input the actual working condition of the main bearing according to the actual working condition of the large roadheader; Step 3. Calculate the load distribution of the main bearing according to the Hertz contact theory and the deformation coordination equation; Step 4. According to the load distribution of the main bearing, the program of the main drive bearing life evaluation system of the large roadheader is called to calculate the rated life of the main bearing.

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