CN114936436B - Method for establishing spiral seal abrasion model of roller bit under high-temperature and dynamic load working conditions - Google Patents
Method for establishing spiral seal abrasion model of roller bit under high-temperature and dynamic load working conditions Download PDFInfo
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Abstract
The invention discloses a method for establishing a spiral seal abrasion model of a roller bit under high-temperature and dynamic load working conditions, which is applied to the field of abrasion models. Analyzing friction and wear properties of the friction pair material of the sealing structure at different temperatures and loads through a ball-block friction experiment, and selecting a basic model under a high-temperature dynamic load working condition; based on a basic model under a high-temperature working condition, temperature influence parameters are introduced to correct and fit, data of a ball-block friction experiment are input to obtain an optimal solution, and a spiral seal abrasion model of the roller bit under the high-temperature working condition is established; and (3) based on improvement of a basic model under a dynamic load working condition, carrying out formula deduction on a wear mechanism between ball test pieces under a dynamic load, deducing a relation between a wear volume and time according to a Hertz point contact theory, and establishing a spiral seal wear model of the roller bit under the dynamic load working condition. The built model can accurately simulate the abrasion mechanism under the working condition of high temperature and dynamic load, and provides theoretical support for the abrasion-proof improved design scheme.
Description
Technical Field
The invention relates to the field of wear models, in particular to a method for establishing a spiral seal wear model of a roller bit under a high-temperature dynamic load working condition.
Background
In 2016, the screw combined sealing structure based on the thought of sand discharge is proposed by the Wen et al, the sealing structure and the sealing device are designed, the sealing performance and the wear performance of the screw combined sealing structure are researched by adopting a simulation and experiment method, and the screw combined sealing structure is applied to actual drilling of cone bit of 8 1/2 SLM537G-1 model and 12/4 SLM517GK-1 model, so that a good effect is obtained.
For the spiral seal of the roller bit, the seal failure causes the bit to fail, the drilling cost is increased, the drilling efficiency is reduced, and the tripping times are increased. The direct economic losses such as drill bit failure caused by seal failure are immeasurable each year, and the indirect economic losses such as safety production accidents caused by seal failure are larger.
Therefore, the method for building the spiral seal abrasion model of the roller bit and predicting the abrasion degree of the spiral seal of the roller bit has important significance for improving the sealing performance of the bit, prolonging the service life of the bit, reducing the drilling cost and improving the drilling efficiency.
In the existing wear model, the research on the wear model under the working conditions of static load, normal temperature, high temperature and dynamic load is very little. Under the action of high temperature and dynamic load, the physical, chemical and mechanical properties of the material are changed, and the friction and wear properties of the material are greatly affected. Therefore, the research thought of the static load and normal temperature working condition abrasion model is not suitable for researching the abrasion model under the high temperature and dynamic load working conditions, and the spiral seal of the roller bit cannot meet the requirements of the roller bit under the high temperature and dynamic load working conditions in daily work.
Therefore, how to provide a method for establishing a spiral seal abrasion model of a roller bit under the working conditions of high temperature and dynamic load, which can meet the requirements of the spiral seal of the roller bit under the working conditions of high temperature and dynamic load in daily work and reasonably predict the abrasion degree of the spiral seal of the roller bit, is a problem to be solved by the person skilled in the art.
Disclosure of Invention
In view of this, the invention provides a method for establishing a spiral seal abrasion model of a roller bit under the working condition of high temperature and dynamic load. Firstly, friction and wear performances of a friction pair material of a sealing structure under different temperatures and different loads are obtained through a ball-block friction experiment, and an Arcard wear model is selected as a basic model of spiral seal wear of the roller bit under a high-temperature working condition and a basic model of spiral seal wear of the roller bit under a dynamic load working condition; then, introducing temperature influence parameters on the basis of an Archard abrasion model, fitting, inputting data of a ball-block friction experiment to obtain an optimal solution, and establishing a spiral seal abrasion model of the roller bit under a high-temperature working condition; the method comprises the steps of carrying out formula deduction on the abrasion mechanism between ball test pieces under dynamic load by improving an Archard abrasion model, deducing the relation between abrasion volume and time according to the Hertz point contact theory, and establishing a spiral seal abrasion model of the roller bit under dynamic load working conditions; finally, simulation verification is carried out on the spiral seal abrasion model of the roller bit under the high-temperature working condition, and the simulation verification comprises the following steps: static contact simulation, dynamic friction heat generation simulation and dynamic friction wear simulation are carried out to obtain a more accurate wear volume, the change amount of wear on the groove depth of the spiral ring is calculated according to the geometric relationship through the wear volume, and the sealing effect is not basically influenced by the current high-temperature working condition based on the analysis of the optimal groove depth value; simulating a spiral seal abrasion model of the roller bit under a dynamic load working condition, simulating ball-block abrasion under dynamic load and static load by adopting finite element simulation, comparing a simulation result with a test result, verifying the reliability and correctness of a theoretical model and a test, and obtaining that a dynamic load peak value has great influence on contact stress on a seal ring thread and is in a linear relation; the larger the dynamic load peak value is, the more and more severe the abrasion of the sealing ring is; the frequency has little effect on the contact stress of the seal ring surface. The built spiral seal abrasion model of the roller bit under the high-temperature and dynamic load working conditions can accurately simulate the abrasion mechanism of the spiral seal of the roller bit under the high-temperature and dynamic load working conditions, provides theoretical support for the abrasion-proof improved design scheme of the actual spiral seal structure of the roller bit, and has important significance in improving the spiral seal performance of the roller bit, prolonging the spiral seal life of the roller bit, reducing the drilling cost and improving the drilling efficiency.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
The method for establishing the spiral seal abrasion model of the roller bit under the high-temperature and dynamic load working conditions comprises the following steps:
Step (1): the friction and wear performance of the friction pair material of the sealing structure under different temperatures and different loads is obtained through a ball-block friction experiment, and a basic model for spiral seal wear of the roller bit under a high-temperature working condition and a basic model for spiral seal wear of the roller bit under a dynamic load working condition are selected.
Step (2) based on a basic model of spiral seal abrasion of the roller bit under a high-temperature working condition, introducing temperature influence parameters to correct, and obtaining a preliminary model of spiral seal abrasion of the roller bit under the high-temperature working condition; fitting a preliminary model of spiral seal abrasion of the roller bit under a high-temperature working condition, inputting data of a ball-block friction experiment to obtain an optimal solution, and establishing the model of spiral seal abrasion of the roller bit under the high-temperature working condition.
Step (3): based on the improvement of a basic model of spiral seal abrasion of the roller bit under the dynamic load working condition, the formula deduces the abrasion mechanism between ball block test pieces under the dynamic load, and then the relation between the abrasion volume and time is deduced according to the Hertz point contact theory, so as to establish the spiral seal abrasion model of the roller bit under the dynamic load working condition.
Optionally, in the step (1), a control variable method is adopted in the ball-block friction experiment, so that the friction coefficient change condition between friction pairs at different temperatures and under different loads, the abrasion loss and the surface morphology of the worn block test piece are measured, and the friction and abrasion performance of the friction pair material with the sealing structure at different temperatures and under different loads is obtained.
Optionally, in the step (1), the basic model of the spiral seal abrasion of the roller bit under the high-temperature working condition and the basic model of the spiral seal abrasion of the roller bit under the dynamic load working condition are Archard abrasion models.
Optionally, in step (2), the temperature influencing parameter includes: temperature coefficient, pressure index and velocity index.
Based on an Archard abrasion model, a temperature coefficient, a pressure index and a speed index are introduced for correction, and a preliminary model of spiral seal abrasion of the roller bit under a high-temperature working condition is obtained.
The initial model of the spiral seal abrasion of the roller bit under the high-temperature working condition is as follows:
Wherein k s is the temperature coefficient; t is the temperature; t 0 is room temperature, and 25 ℃; m is the pressure index; n is a velocity index; v is the sliding speed in mm/s; is the depth wear rate; p is the pressure of the contact wear area in MPa; k' is the wear coefficient.
Optionally, in step (2), fitting a preliminary model of spiral seal abrasion of the roller bit under a high-temperature working condition, inputting data of a ball-block friction experiment to obtain an optimal solution, and building the model of spiral seal abrasion of the roller bit under the high-temperature working condition, wherein the model specifically comprises the following steps: inputting a preliminary model of spiral seal abrasion of the roller bit under a high-temperature working condition into 1st Opt software, defining solving parameters and a value range, including a temperature coefficient k s, an abrasion coefficient k', a pressure index m and a speed index n, obtaining a fitting code, inputting data of a ball-block friction experiment into the fitting code, obtaining an optimal solution, and establishing the spiral seal abrasion model of the roller bit under the high-temperature working condition.
The spiral seal abrasion model of the roller bit under the high-temperature working condition is as follows:
Wherein, Is the depth wear rate; t is the temperature; t 0 is room temperature, and 25 ℃; p is the pressure of the contact wear area in MPa; v is the sliding speed in mm/s.
Optionally, in the step (3), an improvement is performed based on an Archard abrasion model, and an abrasion mechanism between ball test pieces under dynamic load is deduced according to a formula, so that the following results are obtained:
Wherein dh is the wearing depth infinitesimal in mm; k 1 is the improvement in the wear coefficient in the equation as a dimensionless constant; v is the relative sliding speed of the ball and block test pieces, and the unit is m/s; σ 0 (t) is a function of the contact stress at the contact point over time, and the expression can be rewritten as σ 0(t)＝σs S (t) according to the contact principle, where the S (t) contact area function is related to the dynamic load amplitude variation; h m is a hardness parameter of the bulk test piece material, which is a property of the material itself.
Integrating the time t of the improved model based on the Archard abrasion model, wherein k 1, v and Hm are constants, and obtaining:
Optionally, in step (3), after integrating the time t of the improved expression based on the Archard abrasion model, the relationship between the abrasion volume and time is deduced according to the hertz point contact theory, and the abraded volume V 0 is written as a relationship of the abrasion volume infinitesimal dV 0 at the time t, as follows:
Wherein K is the introduced wear coefficient; l is the relative sliding distance of the friction pair; e * is the equivalent elastic modulus of the two objects; r is the radius of the ball test piece; and theta is the cutting half angle, and the value range of the theta is between (0 and pi/8).
The normal load applied to the ball test piece is a sinusoidal dynamic load, and the function of the dynamic load changing along with time is as follows: f (t) =x 0 +10sin ωt, integrating the relation of the wear volume infinitesimal dV 0 when the worn volume V 0 is written as t to obtain a wear volume improvement formula when the wear duration is t 0 under dynamic load, and building a spiral seal wear model of the roller bit under dynamic load working condition as follows:
wherein K is an introduced abrasion coefficient, l is the relative sliding distance of the friction pair, E * is the equivalent elastic modulus of two objects, r is the radius of the ball test piece, and θ is the cutting half angle.
Optionally, the method further comprises: after the spiral sealing abrasion model of the roller bit under the high-temperature working condition and the spiral sealing abrasion model of the roller bit under the dynamic loading working condition are established, the spiral sealing abrasion model of the roller bit under the high-temperature working condition and the spiral sealing abrasion model of the roller bit under the dynamic loading working condition are verified in a simulation mode.
Simulation verification of the spiral seal abrasion model of the roller bit under the high-temperature working condition is specifically as follows:
And adopting finite element software to perform static contact simulation to obtain the contact stress distribution condition of the friction pair at the moment of the loading process.
By adopting dynamic friction heat generation simulation, the friction heat generation quantity between the ball blocks is not obvious under the test working condition, and the influence of the friction heat generation on the temperature is ignored.
By adopting dynamic friction and wear simulation and using Abaqus finite element simulation software, a secondary development user subroutine Umeshmotion is introduced, a self-adaptive meshing technology is called to realize the process of loss of materials due to friction of a model, the change condition of the wear volume under different temperatures and loads is obtained, and the change condition is compared with a test result to obtain a more accurate wear volume.
And calculating the change amount of abrasion to the groove depth of the spiral ring according to the geometric relationship through the abrasion volume, and calculating the optimal groove depth value.
Simulation verification of a spiral seal abrasion model of the roller bit under a dynamic load working condition is specifically as follows:
And simulating ball-block abrasion under dynamic load and static load through finite element simulation, and comparing a simulation result with a test result.
Compared with the prior art, the method for establishing the spiral seal abrasion model of the roller bit under the working conditions of high temperature and dynamic load is provided. Firstly, friction and wear properties of a friction pair material of a sealing structure under different temperatures and different loads are obtained through a ball-block friction experiment, and an Archard wear model is selected as a basic model of spiral seal wear of a roller bit under a high-temperature working condition and a basic model of spiral seal wear of the roller bit under a dynamic load working condition; then, introducing temperature influence parameters on the basis of an Archard abrasion model, fitting, inputting data of a ball-block friction experiment to obtain an optimal solution, and establishing a spiral seal abrasion model of the roller bit under a high-temperature working condition; the method comprises the steps of carrying out formula deduction on the abrasion mechanism between ball test pieces under dynamic load by improving an Archard abrasion model, deducing the relation between abrasion volume and time according to the Hertz point contact theory, and establishing a spiral seal abrasion model of the roller bit under dynamic load working conditions; finally, simulation verification is carried out on the spiral seal abrasion model of the roller bit under the high-temperature working condition, and the simulation verification comprises the following steps: static contact simulation, dynamic friction heat generation simulation and dynamic friction wear simulation are carried out to obtain a more accurate wear volume, the change amount of wear on the groove depth of the spiral ring is calculated according to the geometric relationship through the wear volume, and the sealing effect is not basically influenced by the current high-temperature working condition based on the analysis of the optimal groove depth value; simulating a spiral seal abrasion model of the roller bit under a dynamic load working condition, simulating ball-block abrasion under dynamic load and static load by adopting finite element simulation, comparing a simulation result with a test result, verifying the reliability and correctness of a theoretical model and a test, and obtaining that a dynamic load peak value has great influence on contact stress on a seal ring thread and is in a linear relation; the larger the dynamic load peak value is, the more and more severe the abrasion of the sealing ring is; the frequency has little effect on the contact stress of the seal ring surface. The built spiral seal abrasion model of the roller bit under the high-temperature and dynamic load working conditions can accurately simulate the abrasion mechanism of the spiral seal of the roller bit under the high-temperature and dynamic load working conditions, provides theoretical support for the abrasion-proof improved design scheme of the actual spiral seal structure of the roller bit, and has important significance in improving the spiral seal performance of the roller bit, prolonging the spiral seal life of the roller bit, reducing the drilling cost and improving the drilling efficiency.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of the present invention.
FIG. 2 is a schematic of the adhesive wear process of the Archard wear model of the present invention.
FIG. 3 is an enlarged schematic view of the friction pair contact area of a ball test piece under dynamic load based on the Archard wear model improvement of the present invention.
Fig. 4 is a schematic diagram showing a distribution of contact stress of a friction pair of 10N at the time of loading completion obtained by static contact simulation.
Fig. 5 is a schematic diagram of a distribution of 20N contact stress of a friction pair at the time of loading completion obtained by static contact simulation according to the present invention.
Fig. 6 is a schematic diagram showing a distribution of 30N contact stress of a friction pair at the time of loading completion obtained by static contact simulation according to the present invention.
Fig. 7 is a schematic diagram showing a distribution of contact stress of a friction pair at the loading completion time of 40N according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The embodiment of the invention discloses a method for establishing a spiral seal abrasion model of a roller bit under high-temperature and dynamic load working conditions, which is shown in figure 1 and comprises the following steps:
Step (1): by adopting a controlled variable method in a ball-block friction experiment, the temperature and the applied load of a block test piece are respectively changed, the change condition of friction coefficients between friction pairs under different temperatures and different loads and the abrasion quantity and the surface morphology of the worn block test piece are measured, the friction and abrasion performance of a friction pair material with a sealing structure under different temperatures and different loads is obtained, and an Arcard abrasion model is selected as a basic model for spiral seal abrasion of a roller bit under a high-temperature working condition and a basic model for spiral seal abrasion of the roller bit under a dynamic loading working condition, as shown in figure 2.
Step (2) introducing temperature influence parameters based on an Archard abrasion model: the temperature coefficient, the pressure index and the speed index are corrected to obtain a preliminary model of spiral seal abrasion of the roller bit under the high-temperature working condition, which is specifically as follows:
The Archard model is typically applied over a localized area, given a worn area of S1, and dividing both sides of the Archard model by S1 yields:
Wherein F N is a normal load, L is a sliding distance of a ball block test, W' is a total abrasion loss, k is a probability of generating abrasive dust in an abrasion process, P is a pressure (MPa) of a contact abrasion area, H is a Brinell hardness value, and the depth H of the abrasion area is obtained by a formula (1).
The combination formula (1) and the formula (2) can be obtained:
equation (3) is derivable for time t, so deriving time t may result:
Further arrange (4) the order For the depth wear rate,/>For the sliding speed (mm/s), combining k and H into a new wear coefficient k', and correcting under the influence of temperature to obtain a roller bit spiral seal wear preliminary model under the high-temperature working condition, wherein the preliminary model is shown as a formula (5):
Wherein k s is a temperature coefficient, T 0 is room temperature, 25 ℃ is taken, m is a pressure index, and n is a speed index.
Fitting a preliminary model of spiral seal abrasion of the roller bit under a high-temperature working condition, inputting data of a ball-block friction experiment to obtain an optimal solution, and establishing the model of spiral seal abrasion of the roller bit under the high-temperature working condition, wherein the model specifically comprises the following steps:
In 1st opt, a required fitting formula is set as a formula (5) by using a Function statement, solving Parameters and a value range are defined by using Parameters statement, the Parameters comprise a temperature coefficient k s, a wear coefficient k', a pressure index m and a speed index n, fitting is realized according to sequence data defined by variables, and fitting codes and notes are as follows:
inputting data of a ball-block friction experiment into a fitting code, setting a solving algorithm into a universal global optimization algorithm (UGO), setting a convergence criterion as 1E-10, setting the maximum iteration number as 1000, setting the parallel number as 30, setting the control number as 50, setting the convergence judgment number as 15, and performing after-operation finishing to obtain a fitting result as shown in table 1:
TABLE 1
The fitting result shows that the R-square is 0.94, the fitting result is better, the solved parameters are substituted into the formula (5), and the friction and wear model applicable to the 20CrNiMo-40Cr friction pair is finally obtained as shown in the formula (6):
Wherein, Is the depth wear rate; t is the temperature; t 0 is room temperature, and 25 ℃; p is the pressure of the contact wear area in MPa; v is the sliding speed in mm/s.
Step (3): based on the Archard abrasion model, the abrasion mechanism between the ball test pieces under dynamic load is deduced according to a formula, the ball test pieces and the ball test pieces slide relatively in the test process, the cutting depth of the ball test pieces is deepened continuously, and the classical Archard abrasion model cannot react the classical Archard abrasion model directly. Because the friction pair contact form is point contact, a large amount of friction heat is generated at a contact point when relative sliding is carried out, but the whole size of the block test piece is larger, the friction heat dissipation is extremely fast, so that the temperature change is not considered when the classical Arcard abrasion model is improved, and the yield limit sigma s of the friction pair material and the relative sliding speed v of the friction pair are regarded as fixed constants, so that the following improved formula is obtained:
Wherein dh is the wearing depth infinitesimal in mm; k 1 is the improvement in the wear coefficient in the equation as a dimensionless constant; v is the relative sliding speed of the ball and block test pieces, and the unit is m/s; σ 0 (t) is a function of the contact stress at the contact point over time, and the expression can be rewritten as σ 0(t)＝σs S (t) according to the contact principle, where the S (t) contact area function is related to the dynamic load amplitude variation; h m is a hardness parameter of the bulk test piece material, which is a property of the material itself.
Integrating the time t with the improved Archard wear model, k 1、v、Hm as a constant, gives:
And (3) infinitely enlarging the contact area of the friction pair as shown in fig. 3, regarding the surface of the block test piece as an x-y plane, establishing an O-xyz space rectangular coordinate system, analyzing the contact state at any time, and enabling h to infinitely approach 0 under the action of a normal load F, wherein the contact is elliptic Hertz contact under the limit condition.
Deducing the relation between the abrasion volume and time according to the Hertz point contact theory, and establishing a spiral seal abrasion model of the roller bit under the dynamic load working condition, wherein the spiral seal abrasion model specifically comprises the following steps:
According to the hertz point contact theory, an elliptical contact area is formed by the contact between the ball test piece and the block test piece in the test due to the elastic deformation of the test material, the area of the cut-in test block is the elastic deformation generated by the extrusion of the sphere, and the elastic deformation can be expressed as follows by the geometric relationship:
S＝θr2-arcosθ#(9)；
Wherein θ is the cut-in half angle, a is the width, r is the sphere test piece radius, and assuming that the relative sliding distance of the friction pair is l, the worn volume V 0 is:
V0＝Sl＝θr2l-arlcosθ#(10)；
Wherein θ is a half angle of cutting in, a is a width, r is a radius of the ball test piece, l is a relative sliding distance of the friction pair, S is an area of the cutting-in test block, and displacement δ of a point of elastic displacement generated on the surface of the block test piece in the negative direction of the Z axis according to the hertz contact theory of the sphere and the plane can be expressed as:
Wherein h is the depth of the cut-in test block, r is the radius of the ball test piece, delta is the displacement, the distribution of the Hertz pressure in the contact area, and the vertical displacement generated in the z-axis direction is:
wherein, sigma 0 is the pressure of contact center, r is the sphere test piece radius, a is the width, E * is the equivalent elastic modulus of two objects, delta is displacement, all points of elastic deformation on the surface of the block test piece in the contact area are equal in vertical displacement, and when the pressure distribution is generated, the indentation is generated in the elastic half space by a rigid cylinder pressure head, and the resultant force of the contact area is:
Wherein σ 0 is the pressure at the contact center, a is the width, δ is the displacement, and formula (13) is substituted into formula (10):
Wherein σ 0 is the pressure of the contact center, a is the width, E * is the equivalent elastic modulus of two objects, δ is the displacement, r is the radius of the ball test piece, h is the depth of the cut-in test piece, and the parameters affecting the displacement in formula (15) are variables h and a, so the following requirements are satisfied:
And the variables h and a should also meet the contact radius condition:
a2＝rh#(18)；
maximum pressure conditions of the contact area:
Substituting the formula (18) and the formula (19) into the formula (14):
Wherein E * is the equivalent elastic modulus of two objects, r is the radius of the ball test piece, h is the depth of the cut-in test piece, and the relation between the pressure of the Hertz contact center, the normal load and the contact radius can be deduced according to the formula (20) and the formula (19):
Wherein, the dynamic load F is a function of time, E * is the equivalent elastic modulus of two objects, r is the radius of the ball test piece, so the worn volume V 0 of the formula (10) can be written as the worn volume infinitesimal dV 0 at t time:
wherein K is an introduced abrasion coefficient, l is the relative sliding distance of the friction pair, E * is the equivalent elastic modulus of two objects, r is the radius of the ball test piece, and θ is the cutting-in half angle, because not all rough peaks and microprotrusions on the contact area of the friction pair can cause abrasive particles to be generated when the friction pair is abraded; the value of theta is a function of time as the depth of wear changes, but the range of values of theta is between (0-pi/8) as measured.
Because the normal load applied to the ball test piece is a sinusoidal dynamic load, the function of the dynamic load over time is as follows: f (t) =x 0 +10sin ωt, referring to the modified Archard wear model, the formula (22) is integrated, the formula can be rewritten into the wear volume modification formula when the wear duration under dynamic load is t 0, and the helical seal wear model of the roller bit under dynamic load is established as follows:
Wherein K is an introduced abrasion coefficient, l is the relative sliding distance of the friction pair, E * is the equivalent elastic modulus of two objects, r is the radius of a ball test piece, θ is the cutting half angle, and the abrasion model type of Archard is combined to be used in ABAQUS simulation.
The simulation verification of the spiral seal abrasion model of the roller bit under the high-temperature working condition and the spiral seal abrasion model of the roller bit under the dynamic load working condition is specifically as follows:
the simulation of the spiral seal abrasion model of the roller bit under the high-temperature working condition is specifically as follows:
Static contact simulation is performed by using finite element simulation software such as Abaqus, and the contact stress distribution situation of the friction pair at the loading completion time is obtained through steps such as modeling, interaction setting, analysis step and loading, grid division and boundary condition setting, calculation and post-processing, simulation result and analysis, and the like, as shown in fig. 4-7.
There are two sources of temperature: one is that the hot runner system warms the system according to a set temperature, which is a known quantity, applied to the sphere block model in a predefined field manner in the simulation; the other is that the temperature is increased due to the heat generated by friction, and the temperature is needed to be obtained through simulation solution, so that the dynamic friction heat generation simulation is adopted, the friction heat generation simulation basic steps are approximately the same as those of static contact, the friction heat generation quantity between the ball blocks is finally obtained under the test working condition is not obvious, and the influence of friction heat generation on the temperature can be ignored.
By adopting dynamic friction and wear simulation and using Abaqus finite element simulation software, a secondary development user subroutine Umeshmotion is imported as follows:
And (3) invoking a self-adaptive meshing technology to realize the process of losing materials of the model due to friction, obtaining the change condition of the abrasion volume under different temperatures and loads, and comparing with a test result to obtain a more accurate abrasion volume.
And (3) under the high-temperature working condition, the spiral seal abrasion model simulation research of the roller bit obtains the abrasion volume through friction simulation and abrasion simulation, calculates the change amount of abrasion to the groove depth of the spiral ring according to the geometric relationship, and obtains that the current high-temperature working condition basically does not influence the sealing effect based on the analysis of the optimal groove depth value.
The simulation of the spiral seal abrasion model of the roller bit under the dynamic load working condition is specifically as follows:
And the ball-block abrasion under dynamic load and static load is simulated through finite element simulation, the simulation result is compared with the test result, the abrasion volume under dynamic load and the test value are obtained to have good consistency, the abrasion volume change trend under different peak loads and different frequencies is the same as the test result, and the reliability and the correctness of the theoretical model and the test are verified.
Simulation research on a spiral seal abrasion model of the roller bit under a dynamic load working condition shows that a dynamic load peak value has great influence on contact stress on a seal ring thread and is in a linear relation; the larger the dynamic load peak value is, the more and more severe the abrasion of the sealing ring is; the frequency has little effect on the contact stress of the seal ring surface.
The invention discloses a method for establishing a spiral seal abrasion model of a roller bit under a high-temperature and dynamic load working condition. Firstly, friction and wear properties of a friction pair material of a sealing structure under different temperatures and different loads are obtained through a ball-block friction experiment, and an Archard wear model is selected as a basic model of spiral seal wear of a roller bit under a high-temperature working condition and a basic model of spiral seal wear of the roller bit under a dynamic load working condition; then, introducing temperature influence parameters on the basis of an Archard abrasion model, fitting, inputting data of a ball-block friction experiment to obtain an optimal solution, and establishing a spiral seal abrasion model of the roller bit under a high-temperature working condition; the method comprises the steps of carrying out formula deduction on the abrasion mechanism between ball test pieces under dynamic load by improving an Archard abrasion model, deducing the relation between abrasion volume and time according to the Hertz point contact theory, and establishing a spiral seal abrasion model of the roller bit under dynamic load working conditions; finally, simulation verification is carried out on the spiral seal abrasion model of the roller bit under the high-temperature working condition, and the simulation verification comprises the following steps: static contact simulation, dynamic friction heat generation simulation and dynamic friction wear simulation are carried out to obtain a more accurate wear volume, the change amount of wear on the groove depth of the spiral ring is calculated according to the geometric relationship through the wear volume, and the sealing effect is not basically influenced by the current high-temperature working condition based on the analysis of the optimal groove depth value; simulating a spiral seal abrasion model of the roller bit under a dynamic load working condition, simulating ball-block abrasion under dynamic load and static load by adopting finite element simulation, comparing a simulation result with a test result, verifying the reliability and correctness of a theoretical model and a test, and obtaining that a dynamic load peak value has great influence on contact stress on a seal ring thread and is in a linear relation; the larger the dynamic load peak value is, the more and more severe the abrasion of the sealing ring is; the frequency has little effect on the contact stress of the seal ring surface. The built spiral seal abrasion model of the roller bit under the high-temperature and dynamic load working conditions can accurately simulate the abrasion mechanism of the spiral seal of the roller bit under the high-temperature and dynamic load working conditions, provides theoretical support for the abrasion-proof improved design scheme of the actual spiral seal structure of the roller bit, and has important significance in improving the spiral seal performance of the roller bit, prolonging the spiral seal life of the roller bit, reducing the drilling cost and improving the drilling efficiency.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (4)
1. The method for establishing the spiral seal abrasion model of the roller bit under the high-temperature and dynamic load working condition is characterized by comprising the following steps of:
Step (1): obtaining friction and wear properties of a friction pair material of a sealing structure under different temperatures and different loads through a ball-block friction experiment, and selecting a basic model for spiral seal wear of the roller bit under a high-temperature working condition and a basic model for spiral seal wear of the roller bit under a dynamic load working condition;
step (2) based on the basic model of the spiral seal abrasion of the roller bit under the high-temperature working condition, introducing temperature influence parameters to correct, and obtaining a preliminary model of the spiral seal abrasion of the roller bit under the high-temperature working condition; fitting the initial model of the spiral seal abrasion of the roller bit under the high-temperature working condition, inputting data of the ball-block friction experiment to obtain an optimal solution, and establishing the model of the spiral seal abrasion of the roller bit under the high-temperature working condition;
step (3): based on the basic model of spiral seal abrasion of the roller bit under the dynamic load working condition, carrying out formula deduction on the abrasion mechanism between ball test pieces under the dynamic load, deducing the relation between abrasion volume and time according to the Hertz point contact theory, and establishing a spiral seal abrasion model of the roller bit under the dynamic load working condition;
In the step (1), a basic model of spiral seal abrasion of the roller bit under the high-temperature working condition and a basic model of spiral seal abrasion of the roller bit under the dynamic loading working condition are Archard abrasion models;
In step (2), the temperature influencing parameters include: temperature coefficient, pressure index and velocity index;
Based on an Archard abrasion model, introducing the temperature coefficient, and correcting the pressure index and the speed index to obtain a preliminary model of spiral seal abrasion of the roller bit under a high-temperature working condition;
The initial model of the spiral seal abrasion of the roller bit under the high-temperature working condition is as follows:
Wherein k s is the temperature coefficient; t is the temperature; t 0 is room temperature, and 25 ℃; m is the pressure index; n is a velocity index; v is the sliding speed in mm/s; is the depth wear rate; p is the pressure of the contact wear area in MPa; k' is the wear coefficient;
In the step (3), based on the Archard abrasion model, the abrasion mechanism between the ball test pieces under dynamic load is deduced by a formula, and the abrasion mechanism is obtained:
Wherein dh is the wearing depth infinitesimal in mm; k 1 is the improvement in the wear coefficient in the equation as a dimensionless constant; v is the relative sliding speed of the ball and block test pieces, and the unit is m/s; σ 0 (t) is a function of the change in contact stress at the contact point over time, and the expression is rewritten to σ 0(t)＝σs S (t) according to the contact principle, where the S (t) contact area function is related to the change in dynamic load amplitude; h m is the hardness parameter of the block test piece material, and is the attribute of the material;
integrating the time t of the improved Archard abrasion model, wherein k 1, v and Hm are constants, and obtaining:
In the step (3), after integrating the improved expression based on the Archard abrasion model to obtain the time t, according to the hertz point contact theory, the relation between the abrasion volume and the time is deduced, and the abrasion volume V 0 is written as the relation of the abrasion volume infinitesimal dV 0 at the time t, as follows:
Wherein K is the introduced wear coefficient; 1 is the relative sliding distance of the friction pair; e * is the equivalent elastic modulus of the two objects; r is the radius of the ball test piece; theta is a cutting-in half angle, and the value range of theta is between 0 and pi/8;
The normal load applied to the ball test piece is a sinusoidal dynamic load, and the function of the dynamic load changing along with time is as follows: f (t) =x 0 +10sin ωt, integrating the relation of the wear volume infinitesimal dV 0 when the worn volume V 0 is written as t to obtain a wear volume improvement formula when the wear duration is t 0 under dynamic load, and building a spiral seal wear model of the roller bit under dynamic load working condition as follows:
2. The method for establishing the spiral seal abrasion model of the roller bit under the high-temperature dynamic load working condition according to claim 1, wherein in the step (1), a control variable method is adopted in the ball-block friction experiment, the change condition of friction coefficients between friction pairs under different temperatures and different loads, the abrasion loss and the surface morphology of a worn block test piece are measured, and the friction and abrasion performance of the friction pair material with the seal structure under different temperatures and different loads is obtained.
3. The method for building a spiral seal abrasion model of a roller bit under a high-temperature and dynamic load working condition according to claim 1, wherein in the step (2), a preliminary model of the spiral seal abrasion of the roller bit under the high-temperature working condition is fitted, data of the ball-block friction experiment is input to obtain an optimal solution, and the spiral seal abrasion model of the roller bit under the high-temperature working condition is built specifically as follows: inputting a preliminary model of spiral seal abrasion of the roller bit under the high-temperature working condition into 1st Opt software, defining solving parameters and a value range, wherein the solving parameters comprise the temperature coefficient k s, the abrasion coefficient k', the pressure index m and the speed index n to obtain a fitting code, inputting data of the ball-block friction experiment into the fitting code to obtain an optimal solution, and establishing a spiral seal abrasion model of the roller bit under the high-temperature working condition;
the spiral seal abrasion model of the roller bit under the high-temperature working condition is as follows:
wherein, 25 ℃ is taken.
4. The method for building a spiral seal wear model of a roller bit under high-temperature and dynamic load conditions according to claim 1, further comprising: after the spiral sealing abrasion model of the roller bit under the high-temperature working condition and the spiral sealing abrasion model of the roller bit under the dynamic loading working condition are established, simulation verification is carried out on the spiral sealing abrasion model of the roller bit under the high-temperature working condition and the spiral sealing abrasion model of the roller bit under the dynamic loading working condition;
simulation verification of the spiral seal abrasion model of the roller bit under the high-temperature working condition is specifically as follows:
static contact simulation is carried out by adopting finite element software, so that the contact stress distribution condition of the friction pair at the moment of loading process is obtained;
by adopting dynamic friction heat generation simulation, the friction heat generation quantity between the ball blocks is not obvious under the test working condition, and the influence of the friction heat generation on the temperature is ignored;
adopting dynamic friction and wear simulation, using Abaqus finite element simulation software, importing a secondary development user subroutine Umeshmotion, calling a self-adaptive grid division technology to realize the process of loss of materials of the model due to friction, obtaining the change condition of the wear volume under different temperatures and loads, and comparing with test results to obtain more accurate wear volume;
calculating the change amount of abrasion to the groove depth of the spiral ring according to the geometric relationship through the abrasion volume, and calculating an optimal groove depth value;
Simulation verification of the spiral seal abrasion model of the roller bit under the dynamic load working condition is specifically as follows:
And simulating ball-block abrasion under dynamic load and static load through finite element simulation, and comparing a simulation result with a test result.
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