CN114936436B - Method for establishing spiral seal abrasion model of roller bit under high-temperature and dynamic load working conditions - Google Patents

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

Establishment of wear model of spiral seal of cone drill bit under high temperature and dynamic load conditions

Technical Field

The invention relates to the field of wear models, and in particular to a method for establishing a wear model of a spiral seal of a roller drill under high temperature and dynamic load conditions.

Background technique

In 2016, Zhou Yi et al. proposed a spiral combined sealing structure based on the "sand removal" idea, designed the sealing structure and sealing device, and used simulation and experimental methods to study its sealing performance and wear performance. It was applied to the actual drilling of 8 1/2SLM537G-1 and 12 1/4 SLM517GK-1 roller bits, and achieved good results.

For the spiral seal of the roller bit, seal failure leads to drill bit failure, increased drilling costs, reduced drilling efficiency, and increased tripping times. The direct economic losses caused by seal failure such as drill bit failure are incalculable every year, and the indirect economic losses such as safety accidents caused by seal failure are even greater.

Therefore, establishing a wear model for the spiral seal of a roller drill bit and predicting the wear degree of the spiral seal of a roller drill bit are of great significance for improving the sealing performance of the drill bit, increasing the life of the drill bit, reducing drilling costs, and improving drilling efficiency.

The existing wear models are mainly for static load and normal temperature conditions, and there are few studies on wear models under high temperature and dynamic load conditions. Because the physical, chemical and mechanical properties of materials will change under high temperature and dynamic load, their friction and wear properties will also be greatly affected. Therefore, the research ideas of static load and normal temperature wear models are not suitable for the research of wear models under high temperature and dynamic load conditions, and cannot meet the requirements of roller drill bit spiral seals under high temperature and dynamic load conditions in daily work.

Therefore, how to provide a method for establishing a wear model of the spiral seal of a roller drill bit under high temperature and dynamic load conditions that can meet the requirements of the spiral seal of a roller drill bit in daily work under high temperature and dynamic load conditions and reasonably predict the wear degree of the spiral seal of the roller drill bit is an urgent problem that technical personnel in this field need to solve.

Summary of the invention

In view of this, the present invention proposes a method for establishing a wear model of the spiral seal of a roller drill bit under high temperature and dynamic load conditions. First, through the ball-block friction experiment, the friction and wear performance of the sealing structure friction pair material under different temperatures and different loads is obtained, and the Archard wear model is selected as the basic model of the spiral seal wear of the roller drill bit under high temperature conditions and the basic model of the spiral seal wear of the roller drill bit under dynamic load conditions; then, by introducing temperature influencing parameters on the basis of the Archard wear model and fitting, the data of the ball-block friction experiment is input to obtain the optimal solution, and the wear model of the spiral seal of the roller drill bit under high temperature conditions is established; by improving the Archard wear model, the wear mechanism between the ball-block specimens under dynamic load is derived, and then according to the Hertz point contact theory, the relationship between the wear volume and time is derived, and the wear model of the spiral seal of the roller drill bit under dynamic load conditions is established; finally, the high temperature The wear model of the spiral seal of the roller drill bit under working conditions is simulated and verified, including: static contact simulation, dynamic friction heat generation simulation, dynamic friction wear simulation, to obtain a more accurate wear volume. Through the wear volume, the change in the wear on the spiral groove depth is calculated according to the geometric relationship. Based on the analysis of the optimal groove depth value, it is obtained that the current high temperature working condition will basically not affect the sealing effect; for the simulation of the wear model of the spiral seal of the roller drill bit under dynamic load conditions, finite element simulation is used to simulate the ball-block wear under dynamic and static loads, and the simulation results are compared with the experimental results to verify the reliability and correctness of the theoretical model and the experiment. It is concluded that the dynamic load peak has a great influence on the contact stress on the sealing ring thread, and the relationship is linear; the larger the dynamic load peak, the more severe the wear of the sealing ring will be; the frequency has almost no effect on the contact stress on the surface of the sealing ring. The above-mentioned wear model of the spiral seal of the roller drill bit under high temperature and dynamic load conditions can accurately simulate the wear mechanism of the spiral seal of the roller drill bit under high temperature and dynamic load conditions, and provide theoretical support for the anti-wear improvement design scheme of the spiral seal structure of the actual roller drill bit. It is of great significance to improve the performance of the spiral seal of the roller drill bit, increase the life of the spiral seal of the roller drill bit, reduce drilling costs, and improve drilling efficiency.

In order to achieve the above object, the present invention adopts the following technical solution:

The method for establishing the wear model of the spiral seal of a roller drill bit under high temperature and dynamic load conditions includes:

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 ball-block friction experiments, and the basic model of spiral seal wear of the roller bit under high temperature conditions and the basic model of spiral seal wear of the roller bit under dynamic load conditions are selected.

Step (2) is based on the basic model of spiral seal wear of the roller drill bit under high temperature conditions, and the temperature influencing parameters are introduced for correction to obtain a preliminary model of spiral seal wear of the roller drill bit under high temperature conditions; the preliminary model of spiral seal wear of the roller drill bit under high temperature conditions is fitted, and the data of the ball-block friction experiment is input to obtain the optimal solution, and the spiral seal wear model of the roller drill bit under high temperature conditions is established.

Step (3): Based on the basic model of spiral seal wear of roller drill bits under dynamic load conditions, the wear mechanism between ball block specimens under dynamic load is improved, and then the relationship between wear volume and time is derived based on Hertz point contact theory to establish a spiral seal wear model of roller drill bits under dynamic load conditions.

Optionally, in step (1), a controlled variable method is used in the ball-block friction experiment to measure the change in the friction coefficient between the friction pairs at different temperatures and different loads, as well as the wear amount and surface morphology of the block specimen after wear, to obtain the friction and wear performance of the sealing structure friction pair material at different temperatures and different loads.

Optionally, in step (1), the basic model of spiral seal wear of the roller drill bit under high temperature conditions and the basic model of spiral seal wear of the roller drill bit under dynamic load conditions are both Archard wear models.

Optionally, in step (2), the temperature influencing parameters include: temperature coefficient, pressure index and velocity index.

Based on the Archard wear model, the temperature coefficient, pressure index and speed index were introduced for correction, and a preliminary model of spiral seal wear of roller drill bits under high temperature conditions was obtained.

The preliminary model of spiral seal wear of roller bit under high temperature conditions is as follows:

Where, k _s is the temperature coefficient; T is the temperature; T ₀ is the room temperature, which is 25°C; m is the pressure index; n is the velocity index; v is the sliding velocity, in mm/s; is the depth wear rate; P is the pressure in the contact wear area, in MPa; k' is the wear coefficient.

Optionally, in step (2), a preliminary model of spiral seal wear of a roller drill bit under high temperature conditions is fitted, data from a ball-block friction experiment is input to obtain an optimal solution, and a spiral seal wear model of a roller drill bit under high temperature conditions is established. Specifically, the preliminary model of spiral seal wear of a roller drill bit under high temperature conditions is input into 1stOpt software and solution parameters and value ranges are defined, including temperature coefficient k _s , wear coefficient k', pressure index m and speed index n, to obtain a fitting code, data from a ball-block friction experiment is input into the fitting code, an optimal solution is obtained, and a spiral seal wear model of a roller drill bit under high temperature conditions is established.

The wear model of the spiral seal of the roller drill bit under high temperature conditions is as follows:

in, is the depth wear rate; T is the temperature; _T0 is the room temperature, which is 25°C; P is the pressure in the contact wear area, in MPa; v is the sliding velocity, in mm/s.

Optionally, in step (3), based on the Archard wear model, the wear mechanism between the ball block specimens under dynamic load is improved and the formula is derived to obtain:

Among them, dh is the wear depth element, in mm; _k1 is the wear coefficient in the improved equation, which is a dimensionless constant; v is the relative sliding velocity of the ball and block specimen, in m/s; _σ0 (t) is the function of the change of contact stress at the contact point with time. According to the contact principle, the expression can be rewritten as _σ0 (t)= _σsS (t), where S(t) is the contact area function and its size is related to the change of dynamic load amplitude; _Hm is the hardness parameter of the block specimen material, which is a property of the material itself.

The improved formula based on Archard wear model is integrated over time t, with k ₁ , v, and Hm as constants, and we get:

Optionally, in step (3), after integrating the improved formula based on Archard wear model with respect to time t, the relationship between the wear volume and time is derived according to Hertz point contact theory, and the wear volume V ₀ is written as the relationship of the wear volume microelement dV ₀ at time t, as follows:

Among them, 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 specimen; θ is the cutting half angle, and the value range of θ is between (0-π/8).

The normal load on the ball specimen is a sinusoidal dynamic load. The function of the dynamic load changing with time is: F(t) = x ₀ +10sinωt. The relationship between the wear volume V ₀ and the wear volume microelement dV ₀ at time t is integrated to obtain the improved formula of the wear volume when the wear time is t ₀ under dynamic load. The wear model of the spiral seal of the cone drill bit under dynamic load conditions is established as follows:

Among them, 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 specimen, and θ is the cutting half angle.

Optionally, it also includes: after establishing the spiral seal wear model of the roller drill bit under high temperature conditions and the spiral seal wear model of the roller drill bit under dynamic load conditions, simulation verification is performed on the spiral seal wear model of the roller drill bit under high temperature conditions and the spiral seal wear model of the roller drill bit under dynamic load conditions.

The simulation verification of the spiral seal wear model of the cone drill bit under high temperature conditions is as follows:

Finite element software is used to perform static contact simulation to obtain the contact stress distribution of the friction pair during the loading process.

By using dynamic frictional heat generation simulation, it is found that the frictional heat generation between the balls is not obvious under the test conditions, and the effect of frictional heat generation on temperature can be ignored.

Dynamic friction and wear simulation was adopted, Abaqus finite element simulation software was used, the secondary development user subroutine Umeshmotion was imported, and the adaptive meshing technology was called to realize the process of material loss due to friction in the model. The wear volume change under different temperatures and loads was obtained, and compared with the test results to obtain a more accurate wear volume.

The change in the spiral groove depth caused by wear is calculated based on the wear volume and geometric relationship, and the optimal groove depth value is calculated.

The simulation verification of the wear model of the spiral seal of the cone drill bit under dynamic load conditions is as follows:

The ball-block wear under dynamic and static loads was simulated by finite element simulation, and the simulation results were compared with the experimental results.

It can be seen from the above technical solutions that, compared with the prior art, the present invention proposes a method for establishing a wear model of the spiral seal of a roller drill bit under high temperature and dynamic load conditions. First, through the ball-block friction experiment, the friction and wear performance of the friction pair material of the sealing structure under different temperatures and different loads is obtained, and the Archard wear model is selected as the basic model of the spiral seal wear of the roller drill bit under high temperature conditions and the basic model of the spiral seal wear of the roller drill bit under dynamic load conditions; then, by introducing temperature influencing parameters on the basis of the Archard wear model and fitting, the data of the ball-block friction experiment is input to obtain the optimal solution, and the wear model of the spiral seal of the roller drill bit under high temperature conditions is established; by improving the Archard wear model, the wear mechanism between the ball-block specimens under dynamic load is derived, and then according to the Hertz point contact theory, the relationship between the wear volume and time is derived, and the wear model of the spiral seal of the roller drill bit under dynamic load conditions is established; finally, the high temperature The wear model of the spiral seal of the roller drill bit under working conditions is simulated and verified, including: static contact simulation, dynamic friction heat generation simulation, dynamic friction wear simulation, to obtain a more accurate wear volume. Through the wear volume, the change in the wear on the spiral groove depth is calculated according to the geometric relationship. Based on the analysis of the optimal groove depth value, it is obtained that the current high temperature working condition will basically not affect the sealing effect; for the simulation of the wear model of the spiral seal of the roller drill bit under dynamic load conditions, finite element simulation is used to simulate the ball-block wear under dynamic and static loads, and the simulation results are compared with the experimental results to verify the reliability and correctness of the theoretical model and the experiment. It is concluded that the dynamic load peak has a great influence on the contact stress on the sealing ring thread, and the relationship is linear; the larger the dynamic load peak, the more severe the wear of the sealing ring will be; the frequency has almost no effect on the contact stress on the surface of the sealing ring. The above-mentioned wear model of the spiral seal of the roller drill bit under high temperature and dynamic load conditions can accurately simulate the wear mechanism of the spiral seal of the roller drill bit under high temperature and dynamic load conditions, and provide theoretical support for the anti-wear improvement design scheme of the spiral seal structure of the actual roller drill bit. It is of great significance to improve the performance of the spiral seal of the roller drill bit, increase the life of the spiral seal of the roller drill bit, reduce drilling costs, and improve drilling efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

FIG. 1 is a schematic diagram of the process of the present invention.

FIG. 2 is a schematic diagram of the adhesive wear process of the Archard wear model of the present invention.

FIG3 is an enlarged schematic diagram of the contact area of the friction pair of the ball block specimen under dynamic load based on the improved Archard wear model of the present invention.

FIG4 is a schematic diagram of the distribution of the contact stress of the friction pair of 10N when loading is completed through static contact simulation according to the present invention.

FIG5 is a schematic diagram of the distribution of the contact stress of the friction pair of 20N obtained by static contact simulation at the moment when loading is completed according to the present invention.

FIG6 is a schematic diagram of the distribution of the contact stress of the friction pair of 30N obtained by static contact simulation at the moment of loading completion according to the present invention.

FIG. 7 is a schematic diagram showing the distribution of the contact stress of the friction pair of 40N when loading is completed through static contact simulation according to the present invention.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

The embodiment of the present invention discloses a method for establishing a wear model of a spiral seal of a roller drill bit under high temperature and dynamic load conditions, as shown in FIG1 , comprising:

Step (1): By using the control variable method in the ball-block friction experiment, the temperature of the block specimen and the applied load are changed respectively, and the change of the friction coefficient between the friction pairs under different temperatures and different loads, as well as the wear amount and surface morphology of the block specimen after wear are measured. The friction and wear performance of the sealing structure friction pair material under different temperatures and different loads is obtained, and the Archard wear model is selected as the basic model for the wear of the spiral seal of the roller drill bit under high temperature conditions and the basic model for the wear of the spiral seal of the roller drill bit under dynamic load conditions, as shown in Figure 2.

Step (2) is based on the Archard wear model, and the temperature influencing parameters are introduced: temperature coefficient, pressure index and speed index for correction, so as to obtain a preliminary model of spiral seal wear of roller bit under high temperature conditions, which is specifically:

The Archard model is usually applied to a local area. Assuming the area of the wear area is S1, dividing both sides of the Archard model by S1 yields:

Where F _N is the normal load, L is the sliding distance of the ball block test, W' is the total wear, k is the probability of generating wear debris during the wear process, P is the pressure of the contact wear area (MPa), H is the Brinell hardness value, and the wear area depth h can be obtained by formula (1).

Combining equation (1) and equation (2), we can get:

Formula (3) is differentiable with respect to time t, so taking the derivative with respect to time t yields:

Further rearrange equation (4) and let is the depth wear rate, /> is the sliding speed (mm/s), k and H are combined into a new wear coefficient k', and the wear coefficient is corrected under the influence of temperature to obtain the preliminary wear model of the spiral seal of the cone drill bit under high temperature conditions, as shown in formula (5):

Among them, ks _is the temperature coefficient, _T0 is the room temperature, which is 25℃, m is the pressure index, and n is the velocity index.

The preliminary model of spiral seal wear of cone drill bit under high temperature conditions was fitted, and the data of ball-block friction experiment was input to obtain the optimal solution. The spiral seal wear model of cone drill bit under high temperature conditions was established, which is as follows:

In 1stOpt, the required fitting formula is set to Formula (5) using the Function statement, and the solution parameters and value ranges are defined using the Parameters statement, including the temperature coefficient k _s , the wear coefficient k', the pressure index m, and the speed index n. The fitting is performed according to the sequence data defined by the variables. The fitting code and comments are as follows:

The data of the ball-block friction experiment was input into the fitting code, and the solution algorithm was set to the universal global optimization algorithm (UGO), the convergence criterion was 1E-10, the maximum number of iterations was 1000, the number of parallel operations was 30, the number of controls was 50, and the number of convergence judgments was 15. After running, the fitting results were sorted out as shown in Table 1:

Table 1

The fitting result shows that the R-square is 0.94, indicating that the fitting result is good. Substituting the solved parameters into formula (5), the friction and wear model suitable for the 20CrNiMo-40Cr friction pair is finally obtained as shown in formula (6):

in, is the depth wear rate; T is the temperature; _T0 is the room temperature, which is 25°C; P is the pressure in the contact wear area, in MPa; v is the sliding velocity, in mm/s.

Step (3): Based on the improvement of Archard wear model, the wear mechanism between ball and block specimens under dynamic load is derived. During the test, the ball specimen and the block specimen slide relative to each other, and the penetration depth of the ball specimen will continue to deepen, which cannot be directly reflected in the classic Archard wear model. Since the contact form of the friction pair is point contact, although a large amount of friction heat will be generated at the contact point during relative sliding, the overall size of the block specimen is large and the friction heat dissipates very quickly. Therefore, when improving the classic Archard wear model, temperature changes are not considered, and the yield limit _σs of the friction pair material and the relative sliding speed v of the friction pair are regarded as fixed constants, and the following improved formula is obtained:

Among them, dh is the wear depth element, in mm; _k1 is the wear coefficient in the improved equation, which is a dimensionless constant; v is the relative sliding velocity of the ball and block specimen, in m/s; _σ0 (t) is the function of the change of contact stress at the contact point with time. According to the contact principle, the expression can be rewritten as _σ0 (t)= _σsS (t), where S(t) is the contact area function and its size is related to the change of dynamic load amplitude; _Hm is the hardness parameter of the block specimen material, which is a property of the material itself.

The improved formula based on Archard wear model is integrated over time t, with k ₁ , v, and H _m as constants, and we get:

The contact area of the friction pair is infinitely enlarged as shown in Figure 3. The surface of the specimen is regarded as the x-y plane, and the O-xyz space rectangular coordinate system is established. The contact state at any time is analyzed. When h approaches 0 infinitely under the action of the normal load F, it is an elliptical Hertzian contact in the limit case.

According to Hertz point contact theory, the relationship between wear volume and time is derived, and the wear model of the spiral seal of the cone drill bit under dynamic load conditions is established, which is as follows:

According to Hertz's point contact theory, the contact between the ball specimen and the block specimen in the test will form an elliptical contact area due to the elastic deformation of the test material. The area cut into the test block is the elastic deformation of the plane caused by the compression of the sphere, which can be expressed by the geometric relationship as follows:

S = θr ² -arcosθ# (9);

Among them, θ is the cutting half angle, a is the width, r is the radius of the ball specimen, and assuming that the relative sliding distance of the friction pair is l, the worn volume _V0 is:

V ₀ =Sl=θr ² l-arlcosθ#(10);

Among them, θ is the cut-in half angle, a is the width, r is the radius of the ball specimen, l is the relative sliding distance of the friction pair, S is the area of the cut-in test block, and according to the Hertz contact theory of sphere and plane, the displacement δ of the point on the surface of the block specimen where elastic displacement occurs in the negative direction of the Z axis can be expressed as:

Where h is the depth of the specimen, r is the radius of the spherical specimen, δ is the displacement, the distribution of the Hertzian pressure in the contact area, and the vertical displacement in the z-axis direction are:

Among them, _σ0 is the pressure at the contact center, r is the radius of the spherical specimen, a is the width, E ^* is the equivalent elastic modulus of the two objects, δ is the displacement, and the vertical displacement of all points on the surface of the block specimen that undergo elastic deformation in the contact area is equal, indicating that when such a pressure distribution is generated, the indentation is generated by a rigid cylindrical indenter in the elastic half space, and the resultant force in the contact area is:

Where _σ0 is the pressure at the contact center, a is the width, and δ is the displacement. Substituting equation (13) into equation (10), we get:

Among them, _σ0 is the pressure at the contact center, a is the width, E ^* is the equivalent elastic modulus of the two objects, δ is the displacement, r is the radius of the ball specimen, and h is the depth of the cut into the specimen. In formula (15), the parameters that affect the displacement are variables h and a, so the following requirements must be met:

And the variables h and a should also meet the contact radius conditions:

^a2 = rh#(18);

And the maximum pressure conditions in the contact area:

Substituting equation (18) and equation (19) into equation (14), we obtain:

Where, E ^* is the equivalent elastic modulus of the two objects, r is the radius of the spherical specimen, and h is the depth of the cut into the specimen. According to equations (20) and (19), the relationship between the pressure at the Hertz contact center and the normal load and the contact radius can be deduced as follows:

Among them, the dynamic load F is a function of time, E ^* is the equivalent elastic modulus of the two objects, and r is the radius of the spherical specimen. Therefore, the worn volume V ₀ in equation (10) can be written as the wear volume element dV ₀ at time t:

Where 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 specimen, and θ is the cut-in half angle, because not all rough peaks and micro-protrusions on the contact area of the friction pair will lead to the generation of abrasive particles when wear occurs; the value of θ is a function of time as the wear depth changes, but the value range of θ is obtained through actual measurement and is between (0-π/8).

Since the normal load on the ball specimen is a sinusoidal dynamic load, the function of the dynamic load changing with time is: F(t) = x ₀ +10sinωt. Referring to the improved Archard wear model, the integral of equation (22) can be rewritten as the improved wear volume formula when the wear time is t ₀ under dynamic load in this paper. The wear model of the spiral seal of the cone drill bit under dynamic load conditions is established as follows:

Among them, 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 specimen, and θ is the cutting half angle. Combined with the Archard wear model, it can be used in ABAQUS simulation.

It also includes simulation verification of the wear model of the spiral seal of the cone drill bit under high temperature conditions and the wear model of the spiral seal of the cone drill bit under dynamic load conditions. Specifically:

The simulation of the wear model of the spiral seal of the roller drill bit under high temperature conditions is as follows:

Abaqus and other finite element simulation software are used to perform static contact simulation. Through the steps of modeling, setting interaction, analysis step and loading, meshing and boundary condition setting, calculation and post-processing, simulation results and analysis, the contact stress distribution of the friction pair at the moment of loading is obtained, as shown in Figures 4 to 7.

Since temperature has two sources: one is that the hot runner system heats the system according to the set temperature. This temperature is a known quantity and is applied to the ball block model in the form of a predefined field in the simulation; the other is that the heat generated by friction causes the temperature to rise. This part of the temperature needs to be solved through simulation. Therefore, dynamic friction heat generation simulation is adopted. The basic steps of friction heat generation simulation are roughly the same as those of static contact. Finally, it is concluded that the friction heat generation between the balls is not obvious under the test conditions, and the influence of friction heat generation on temperature can be ignored.

Dynamic friction and wear simulation is adopted, Abaqus finite element simulation software is used, and the secondary development user subroutine Umeshmotion is imported as follows:

Adaptive meshing technology is used to realize the process of material loss due to friction in the model, and the change of wear volume under different temperatures and loads is obtained. The wear volume is compared with the test results to obtain a more accurate wear volume.

Simulation study on the wear model of spiral seal of roller drill bit under high temperature conditions. The wear volume is obtained through friction simulation and wear simulation, and the change of wear on the spiral groove depth is calculated according to the geometric relationship. Based on the analysis of the optimal groove depth value, it is found that the current high temperature condition will basically not affect the sealing effect.

The simulation of the wear model of the spiral seal of the cone drill bit under dynamic load conditions is as follows:

Finite element simulation was used to simulate the ball-block wear under dynamic and static loads. The simulation results were compared with the experimental results. It was found that the wear volume under dynamic load was very consistent with the experimental value. The wear volume change trend under different peak loads and different frequencies was the same as the experimental results, verifying the reliability and correctness of the theoretical model and experiment.

The simulation study of the wear model of the spiral seal of a roller drill under dynamic load conditions showed that the dynamic load peak has a great influence on the contact stress on the sealing ring thread, and the relationship is linear; the larger the dynamic load peak, the more severe the wear of the sealing ring will be; and the frequency has almost no effect on the contact stress on the sealing ring surface.

The present invention discloses a method for establishing a wear model of a spiral seal of a roller drill bit under high temperature and dynamic load conditions. First, through a ball-block friction experiment, the friction and wear performance of the friction pair material of the sealing structure under different temperatures and different loads is obtained, and the Archard wear model is selected as the basic model of the spiral seal wear of the roller drill bit under high temperature conditions and the basic model of the spiral seal wear of the roller drill bit under dynamic load conditions; then, by introducing temperature influencing parameters on the basis of the Archard wear model and fitting, the data of the ball-block friction experiment is input to obtain the optimal solution, and the wear model of the spiral seal of the roller drill bit under high temperature conditions is established; by improving the Archard wear model, the wear mechanism between the ball-block specimens under dynamic load is derived, and then according to the Hertz point contact theory, the relationship between the wear volume and time is derived, and the wear model of the spiral seal of the roller drill bit under dynamic load conditions is established; finally, the high temperature The wear model of the spiral seal of the roller drill bit under working conditions is simulated and verified, including: static contact simulation, dynamic friction heat generation simulation, dynamic friction wear simulation, to obtain a more accurate wear volume. Through the wear volume, the change in the wear on the spiral groove depth is calculated according to the geometric relationship. Based on the analysis of the optimal groove depth value, it is obtained that the current high temperature working condition will basically not affect the sealing effect; for the simulation of the wear model of the spiral seal of the roller drill bit under dynamic load conditions, finite element simulation is used to simulate the ball-block wear under dynamic and static loads, and the simulation results are compared with the experimental results to verify the reliability and correctness of the theoretical model and the experiment. It is concluded that the dynamic load peak has a great influence on the contact stress on the sealing ring thread, and the relationship is linear; the larger the dynamic load peak, the more severe the wear of the sealing ring will be; the frequency has almost no effect on the contact stress on the surface of the sealing ring. The above-mentioned wear model of the spiral seal of the roller drill bit under high temperature and dynamic load conditions can accurately simulate the wear mechanism of the spiral seal of the roller drill bit under high temperature and dynamic load conditions, and provide theoretical support for the anti-wear improvement design scheme of the spiral seal structure of the actual roller drill bit. It is of great significance to improve the performance of the spiral seal of the roller drill bit, increase the life of the spiral seal of the roller drill bit, reduce drilling costs, and improve drilling efficiency.

In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred 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 parts can be referred to the method part.

The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to 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)＝σ_s 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.