CN212564073U - Structure for increasing sliding pair dynamic pressure - Google Patents

Abstract

The utility model discloses an increase vice dynamic pressure structure of slip relates to lubricated mechanical equipment technical field of fluid dynamic pressure to each rectangle texture on vice surface of friction carries out the parametric design as independent individual, to the vice operating mode of friction of difference, constructs the space coordinate system to each texture, and gives the controllability of the three degree of freedom of each texture, and wherein, the length of texture is l_xArc of length corresponding to x-axisDegree of alpha_kWidth of texture is l_yWidth of radian beta corresponding to y-axis_kHeight of texture h_k，α_kThe radian of the light beam is-5000 to 5000 mu rad, beta_kThe radian of the arc ranges from-5000 to 5000 mu rad, h_kThe length of the glass is-5 to 5 μm. The utility model discloses a fluid entry, export and, center district and border region to the lubricating film, through the texture of constructing multiple form, combine the synergism between each texture, can make better gathering, the stack of dynamic pressure of liquid film, make the vice better lubricating property that obtains of sliding.

Description

Structure for increasing sliding pair dynamic pressure

Technical Field

The utility model relates to a lubricated mechanical equipment technical field of fluid dynamic pressure, especially an increase vice dynamic pressure structure of sliding.

Background

In industrial production, friction and wear are generally considered as harmful processes, and the research on friction reduction and wear resistance improvement and novel lubricating media are always the key points of the research on the field of friction reduction and wear resistance, and accord with the green and sustainable development trend. In order to reduce friction, a coupling motion friction pair of a traditional mechanical structure generally adopts a mode of increasing a lubricating medium. Although the lubricating medium is added conveniently and efficiently, the lubricating medium cannot be used under certain special working conditions, the service life of a mechanical structure is influenced, the environmental damage is large, and the current social development trend is obviously not facilitated.

The surface texture with a certain size and arrangement is properly processed on the surface of the kinematic friction pair, so that the frictional wear can be reduced, and the tribological performance can be improved. At the present stage, researches and applications for improving the lubricating performance of the friction pair by adopting a surface texture method are numerous, and researchers propose that the lubricating performance of the friction pair is greatly influenced by adopting an asymmetric texture method. However, current research is mainly focused on the distribution and morphology of the same type or individual textures. The study of using various combinations of textures on the same friction pair surface and applying them to the friction pair surface is not mature.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is, from the vice research of same friction, utilize the texture to improve the performance of liquid film to improve the dynamic pressure of lubricated membrane, improve the vice lubricating property of friction, provide an increase slide pair dynamic pressure structure.

The utility model provides a technical scheme that its technical problem adopted is: a structure for increasing the dynamic pressure of sliding pair is composed of two friction bodies moving relatively to each other to form a liquid film between them, and several rectangular textures at one end of said friction bodies, in which the point on opposite surface of said friction body is the origin of texture and the length of texture is l_xThe length corresponds to the x-axis radianα_kWidth of texture is l_yWidth of radian beta corresponding to y-axis_kHeight of texture h_kSaid α is_kThe radian of the beta-radian measure is-5000 to 5000 mu rad_kThe radian range of the arc is-5000 to 5000 mu rad, and h is_kThe length of the glass is-5 to 5 μm.

Further, when said α is_k，β_kAnd h_kWhen the value of (A) is a positive value, the texture is pit type; when the alpha is_k，β_kAnd h_kWhen the value of (a) is negative, the texture is a boss type; the texture near the inlet area of the liquid film is pit-type, and the texture near the outlet of the liquid film is boss-type.

Furthermore, the distribution range of the pit-type texture is in an inverted U shape, and the highest point of the boss is deviated to the central area of the liquid film integrally.

An algorithm for increasing the dynamic pressure structure of a sliding pair, comprising the steps of:

A. building a mathematical model

The friction body is simplified into an upper parallel plate and a lower parallel plate, the length and the width of the parallel plates are respectively L and B, and the thickness of a liquid film between the two parallel plates is h₀A rectangular texture with independent parameters is arranged on the lower parallel plate;

gaps of the textures on the x axis and the y axis are respectively equal to the lengths of the single textures on the x axis and the y axis, and the distance of the residual area of the domain boundary on the x axis and the y axis is calculated to be equal to half of the corresponding length of the single texture;

the lower friction body is used as a reference object, and the upper friction body moves towards the positive direction of the x axis at a speed U;

B. calculating the film thickness

h_tex＝h_k+x_k tan(α_k)+y_k tan(β_k)(k＝1,2,...,N)

Wherein h is_texFor the total film thickness of each texture, the spatial coordinate system parameter of each texture is x_k，y_k，α_k，β_kAnd h_k(k ═ 1, 2.., N), k being the total number of textures, h_kCorrespond to the k textureDepth at coordinate origin, α_kIs the kth texture length and x_kRadian between axes, beta_kIs the k texture width and y_kThe arc between the axes;

h＝h₀+h_tex

wherein h is the film thickness of the whole area of the surface of the friction pair;

C. derivation of transformation

C1, deriving a general form of Reynolds equation, as equation (3), from the force balance analysis of the infinitesimal body and the continuity conditions of the fluid:

wherein eta is the dynamic viscosity of the liquid;

c2, assuming that the influence of the fluid uniform temperature distribution is negative, the film viscosity is limited in the calculation area, ignoring the variation of the liquid viscosity with time and position, simplifying the above equation, as in equation (4):

c3, Reynolds equation expressed in dimensionless form, as in formula (5):

wherein the content of the first and second substances,

p₀is at standard atmospheric pressure;

c4, when the liquid flows to the edge of the calculation area, the liquid film starts to break, and assuming that the pressure generated by the liquid is zero at this time, the formula (6) is obtained:

p|_x＝0＝p|_x＝L＝p|_y＝0＝p|_y＝B＝0

c5, calculating the bearing capacity W generated by the liquid, and obtaining the formula (7):

W＝∫∫pdxdy

further, after the step C5, the method further includes:

D. optimization using adaptive genetic algorithms

D1, parameter coding

Mapping parameters of the texture to a plurality of physical quantities, inserting binary data for coding, constructing a chromosome, and balancing the parameters of the texture in the genetic process;

d2 adaptive selection strategy

The bearing capacity Fitness is used as a Fitness value, as shown in a formula (8), and before the selection process of each generation, the selection is superior and inferior;

Fitness＝W＝∫∫pdxdy

d3 adaptive mutation strategy

Probability of mutation p_mThe relationship with the population generation number is set as the following formula (9):

wherein p is_mTo adapt the mutation probability, G_eEpsilon is a defined self-adaptive adjustment coefficient for the generation of the population;

and returning to the step C3 for recalculation to C5.

Further, in the step B, N is the number of the textures halved.

The utility model has the advantages that:

aiming at the fluid inlet, the fluid outlet, the central area and the boundary area of the lubricating film, by constructing various forms of textures and combining the synergistic effect among the textures, the dynamic pressure of the liquid film can be better gathered and superposed, so that the sliding pair can obtain better lubricating performance. The rectangular textures are used as research objects, the depth of the bottom surface of each texture and the included angle between the bottom surface and the horizontal and vertical coordinate axes are used as parameters, the rectangular microstructures of all the pose positions of the sliding surface are described, and a general mathematical model of the textures is established.

And (4) calculating by adopting a self-adaptive genetic algorithm optimization method to obtain the structure of the surface texture group with higher liquid film dynamic pressure. And establishing a mapping relation between texture posture parameters and chromosomes, calculating population fitness by using a classical Reynolds equation, and taking the increase of hydrodynamic pressure of a liquid film as an optimization object. And the self-adaptive adjustment of each texture is realized through the optimization of the population chromosome.

Drawings

The invention will be further explained with reference to the drawings and examples, wherein:

FIG. 1 is a surface texture model diagram of a sliding pair;

FIG. 2 is a parametric model map of a texture, where (a) is the overall layout of the texture location distribution and (b) is the individual texture geometry parameters;

FIG. 3 is an interpolation and coding map of a multi-parameter chromosome;

FIG. 4 is a computational flow diagram of an adaptive genetic algorithm;

FIG. 5 is a graph of mean fitness and maximum fitness, respectively, versus population generation;

FIG. 6 is a cloud chart of optimal liquid film thickness and pressure distribution during evolution, wherein (a) is the result of genetic algorithm calculation to generations 1, 10 and 20, (b) is the result of genetic algorithm calculation to generations 40, 100 and 200, and (c) is the result of genetic algorithm calculation to generations 500, 950 and 1290;

FIG. 7 is a distribution diagram of a biased texture;

FIG. 8 is a boss type texture topography;

FIG. 9 is a pressure profile of the boss type texture shown in FIG. 8;

fig. 10 is a graph of pressure distribution and texture morphology taken at 0.45 along the normalized y-axis direction.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the intended purpose of the present invention, the following detailed description is given to the embodiments, structures, features and effects according to the present invention with reference to the accompanying drawings and preferred embodiments as follows:

the idea of the application is that textures in different deformation forms are applied to the surface of a friction pair, three parameters are introduced into each texture by combining an adaptive genetic algorithm, a plurality of variables are used as chromosomes to be coded, and an adaptive optimization model of each texture is established.

A structure for increasing the dynamic pressure of sliding pair is disclosed, as shown in fig. 1-3, comprising two friction bodies moving relatively, a liquid film is formed between the friction bodies, a plurality of rectangular textures are arranged at the opposite ends of the friction bodies, wherein, one point on the opposite surfaces of the friction bodies is the origin of the textures, and the length of the textures is l_xAnd the radian of the length corresponding to the x axis is alpha_kWidth of texture is l_yWidth of radian beta corresponding to y-axis_kHeight of texture h_k，α_kThe radian of the light beam is-5000 to 5000 mu rad, beta_kThe radian range of the arc is-5000 to 5000 mu rad, h_kThe length of the glass is-5 to 5 μm. Rectangular texture means that the texture is rectangular in shape when viewed from above, i.e. the texture is rectangular in projection to the XOY plane.

In order to improve the aggregation and superposition of the liquid film dynamic pressure, the sliding pair obtains better lubricating performance. The shape of the texture is optimized. For this purpose, pits and lands are defined, in particular when α_k，β_kAnd h_kWhen the value of (A) is a positive value, the texture is pit type; when alpha is_k，β_kAnd h_kWhen the value of (A) is negative, the texture is a boss type; the texture near the inlet area of the liquid film is pit-type, and the texture near the outlet of the liquid film is boss-type. Preferably, the distribution range of the pit-type texture is in an inverted U shape, and the highest point of the boss is totally biased to the central area of the liquid film.

An algorithm for increasing the dynamic pressure structure of a sliding pair, comprising the steps of:

A. building a mathematical model

The friction body is simplified into an upper parallel plate and a lower parallel plate, the length and the width of the parallel plates are respectively L and B, and the thickness of a liquid film between the two parallel plates is h₀A rectangular texture with independent parameters is arranged on the lower parallel plate. The rectangular texture with independent parameters is referred to as eachThe shape of the individual textures is not linked, each texture shape having its own dimensions.

The gaps of the textures on the x axis and the y axis are equal to the lengths of the single textures on the x axis and the y axis respectively, and the distances of the residual areas of the calculated domain boundary in the directions of the x axis and the y axis are equal to half of the corresponding lengths of the single textures. The texture is projected to be rectangular on an XOY plane, the clearance of the texture on the x axis represents the distance between the two rectangles in the x axis direction, and the clearance of the texture on the y axis represents the distance between the two rectangles in the y axis direction. The remaining region of the calculation domain boundary refers to the free region outside the rectangle.

The lower friction body is used as a reference object, and the upper friction body moves towards the positive direction of the x axis at a speed U. The speed U is the relative movement speed of the upper friction body and the lower friction body.

B. Calculating the film thickness

h_tex＝h_k+x_k tan(α_k)+y_k tan(β_k)(k＝1,2,...,N) (1)

Wherein h is_texFor the total film thickness of each texture, the spatial coordinate system parameter of each texture is x_k，y_k，α_k，β_kAnd h_k(k ═ 1, 2.., N), k being the total number of textures, h_kIs the depth, alpha, of the kth texture at the origin of the corresponding coordinate_kIs the kth texture length and x_kRadian between axes, beta_kIs the k texture width and y_kThe arc between the axes;

h＝h₀+h_tex (2)

wherein h is the film thickness of the whole area of the surface of the friction pair.

Preferably, to reduce the amount of calculation, the parameters of the texture within the calculation domain are symmetrically distributed, and the texture parameter N can be halved.

C. Derivation of transformation

C1, deriving a general form of Reynolds equation, as equation (3), from the force balance analysis of the infinitesimal body and the continuity conditions of the fluid:

wherein eta is the dynamic viscosity of the liquid;

c2, because the lower surface of the friction pair is static, the film thickness of the liquid does not change with time, and the cutting speed of the friction pair is selected to be a lower value. Assuming that the effect of the uniform temperature distribution of the fluid is negative, the film viscosity is limited in the calculation area, ignoring the variation of the liquid viscosity with time and position, the above equation is simplified, as in equation (4):

c3, Reynolds equation expressed in dimensionless form, as in formula (5):

wherein the content of the first and second substances,

p₀is at standard atmospheric pressure;

c4, if cavitation is present in some of the calculation regions, the pressure of this region is set to the saturated vapor pressure of the liquid. When the liquid flows to the edge of the calculation area, the liquid film starts to break, and assuming that the pressure generated by the liquid at this time is zero, the formula (6) is obtained:

p|_x＝0＝p|_x＝L＝p|_y＝0＝p|_y＝B＝0 (6)

c5, calculating the bearing capacity W generated by the liquid, and obtaining the formula (7):

W＝∫∫pdxdy (7)

preferably, after the step C5, the method further includes:

D. optimization using adaptive genetic algorithms

D1, parameter coding

Mapping the parameters of the texture to a plurality of physical quantities, inserting binary data for coding, constructing a chromosome, and balancing the parameters of the texture in the genetic process.

Binary coding is the most common coding method in genetic algorithms. It is simple and easy to implement, meets the minimum character set encoding principle, and is easy to analyze by the pattern theorem. Mapping the parameters defining each texture to a plurality of physical quantities, inserting binary data for coding, and constructing chromosomes, so that the parameters of the texture are better balanced in the genetic process.

D2 adaptive selection strategy

In order to find the maximum value of the oil film bearing capacity, the bearing capacity Fitness is used as a Fitness value, as shown in the formula (8). In order to ensure the stability of the calculation of the optimization model, before the selection process of each generation, the selection is performed with the advantages and the disadvantages;

Fitness＝W＝∫∫pdxdy (8)

d3 adaptive mutation strategy

Probability of mutation p_mThe relationship with the population generation number is set as the following formula (9):

wherein p is_mTo adapt the mutation probability, G_eEpsilon is a defined self-adaptive adjustment coefficient for the generation of the population;

and returning to the step C3 for recalculation to C5.

And performing initial expansion search by adopting the self-adaptive mutation probability, keeping the population diversity, and carefully searching when the search is finished so as to prevent the optimal solution from being damaged. Furthermore, in the optimization process, its operation is performed many times from a broad search to a detailed search. The process ensures that the algorithm not only ensures the comprehensiveness and accuracy of the search, but also can quickly jump out of the local optimization, so that the search time is shorter and the convergence is better.

The concrete case is as follows:

and (3) dispersing the model by adopting a five-point difference method, and writing a program in Matlab software. Firstly, generating original populations randomly, and solving the distribution of the liquid film thickness by combining chromosome codes of each generation of populations.

And solving the fitness of the population by adopting an ultra relaxation iterative method (SOR). The simulation and optimization parameters are as follows:

l_x＝200μm；l_y＝200μm；h ₀2 μm; u is 1 m/s; η is 0.04Pa · s; the number of grids N: 120 x 120. In the present application, the depth at each texture coordinate origin is set to 8 possible values, chosen at equal intervals between 0 and 1.4 μm. Pit or land type and x_kAxis, y_kThe radian of the included angle between the shafts is set to 8 possible values, and the distances between-3500 rads and 3500 rads are respectively selected, as shown in figure 3. Considering the symmetry of the computational domain, the number of textures is defined as halved to 18, each texture introduces 3 variables, each setting 8 possible values. These 8 values are mapped using a linear equation and a three-bit binary code, so that the interpolated and fused binary code has 162 bits.

The initial population and cross probability of the adaptive genetic algorithm are selected according to 60 and 0.6 respectively, and the coefficient is also selected according to 1.01. As the results of the single population are not affected, the fitness of each individual in the population is calculated by adopting a parallel calculation method, so that the calculation speed can be greatly improved. And according to the termination criterion, measuring the convergence characteristic of the adaptive genetic algorithm by using the difference value of the average value of each generation of fitness function. Analysis of maximum and average fitness of the population by Observation over population generations G_eWhen approaching this level, it means that the optimization parameter is approaching an optimal value. Here, through preliminary test analysis, it was found that when the error is selected to be 10^-5And the requirements are completely met. Therefore, the termination operation is determined as follows:

f(G_e+1)-f(G_e)＜10^-5

the calculation flow chart of the adaptive genetic algorithm is shown in fig. 4. First, a batch of 60 binary-coded chromosome-like data was randomly generated, and then the assumed conditions for liquid film thickness distribution were given. And solving the Reynolds equation by adopting a parallel computing method to obtain the fitness value of each individual. And combining the individual fitness value obtained by the current generation population, obtaining the next generation population through self-adaptive selection, crossing and self-adaptive mutation, and repeating the searching process until the stopping condition is met.

The average fitness and the maximum fitness of individuals in the population are respectively equal to the population generation G_eAs shown in fig. 5, it can be found that, for the constructed long encoding chromosome, the average fitness and the maximum fitness value can both grow very stably with the increase of the algebra, and the adaptive genetic algorithm can effectively execute the objective function. Population evolution in the first 200 generations due to mutation probability p_mStill at a large value, it can quickly find a more excellent solution, and the average health and maximum health of this variation interval can increase rapidly, indicating a rapid rise in the load-bearing capacity of the liquid film. With the continuous increase of algebra, the population tends to be optimal, and the mutation probability gradually decreases. As can be seen from fig. 5, after 400 generations, there was no change in the increase in the mean fitness and the maximum fitness of the population. And when the searching process reaches the 1290 th generation, the variation of the population average bearing capacity meets the convergence condition, and the searching process is terminated.

FIGS. 6(a) - (c) are cloud charts of optimal liquid film thickness and pressure distribution in the evolution process. Through the analysis of the pressure distribution cloud picture, the main factors directly influencing the bearing capacity can be better summarized, and certain reference is provided for the research and improvement of other liquid film lubrication parameters in the future. It was found that in the first generation, the microtextured poses were relatively random, resulting in maximum liquid film pressure dispersion. From generation 10 to generation 200, the texture profile began to rapidly adjust.

As can be seen from fig. 6(a) to (b), the morphology of the microtexture exhibits two-stage differentiation. Overall, the liquid film thickness of the microtextured in the fluid inlet zone is greater than the liquid film thickness of the microtextured in the outlet zone. The liquid film thickness of the microtexture near the liquid outlet is less than the liquid film thickness near the exterior of the microtexture, indicating that the microtexture at this location is a plateau. As the concave and convex regions gradually separate, the liquid film pressure gradually increases. In particular, the central region is where the pressure is greatest. FIG. 6(c) shows the evolution process of film thickness and hydraulic pressure in 500 th to 1290 th generations. It can be seen that the division areas of the pits and the lands are clearer. The results show that the microtexture of the two pits in the fourth row in the middle gradually changes into a boss type. The high pressure of the liquid film shifts from row 5 to row 4 of the microtexture, closer to the center of the computational domain.

By analyzing the distribution rule of the rotation axis of the biased texture, as shown in fig. 7, it can be found that the center line of the rotation axis of the dimple texture is distributed in a ring shape, and at the same time, the area of the dimple texture is also in a ring shape. It is due to this factor that the film thickness fluctuates in the radial direction of the ring, providing a precondition for calculating the pressure buildup in the central region of the zone. Because the pit-type textures of the first lines on the two sides are close to the boundary of the calculation domain, the fine adjustment of the rotation angle deviation has little influence on the whole pressure, and the deflection of the texture in the region has little influence on the optimization result. Therefore, considering the timeliness of the calculation, the convergence error of the optimization calculation is defined as 10^-5And the practical requirements are met.

FIG. 8 shows a boss type texture topography. It can be seen that there is a very pronounced regularity in the deflection of the boss. All of the land types are skewed from the central symmetry axis of the computational domain. Due to this phenomenon, it is more favorable for the concentration of high voltage to the central region of the computation domain. Since the central region of the calculation region is far from the liquid film boundary, a larger bearing capacity is more easily obtained by increasing the pressure in the central region.

Here, if the lands in fig. 8 are distributed over the entire calculation area, the pressure distribution is as shown in fig. 9 and compared with the optimized pressure distribution. It was found that the pressure distribution had no significant concentration effect when the lands were distributed over the entire area, with the high pressure areas being independently dispersed primarily at the highest points of the land texture. The bearing capacity is only 8.32N, which is 27% less than the optimized result. Taking the pressure distribution and microtextured morphology at 0.45 along the normalized y-axis direction, as shown in fig. 10, it was found that when the lands in fig. 8 were used uniformly on the surface of the parallel plate, although a certain pressure peak could be generated at the convergence zone of each land, the immediately following divergence zone caused a rapid decrease in pressure, which made it difficult for the pressures to significantly add and accumulate. By analyzing the relationship between the texture topography and pressure as shown by the best results, it was found that the depth of the texture as a whole was from deep to shallow, from the fluid inlet to the center of the calculated area. Especially in the central region of the computational domain, the texture form transitions directly from pit to land, further reducing the film thickness. This converging effect causes the pressure to be further concentrated and superimposed. It is due to this diversity of texture that the liquid film in each texture zone has a significant pressure build-up, rising from the inlet and reaching a maximum at the center.

The simulation was performed with the maximization of the liquid film bearing capacity as the optimization objective. The optimized result shows that the liquid film bearing capacity obtained by the method is 27% higher than that of the uniformly used boss type microtexture. By comparing and analyzing the optimized texture forms and pressure distributions, the optimized textures with different depths and bias are found, the functions of the optimized textures are mainly to enable the liquid film pressure in each area to be effectively superposed and accumulated, and to push a high-pressure area to a central area of the liquid film, and because the edge area is limited by an atmospheric pressure boundary due to the breakage of the liquid film, the method can more easily obtain higher liquid film bearing capacity on the whole.

The invention has been described above with reference to a preferred embodiment, but the scope of protection of the invention is not limited thereto, and various modifications can be made and equivalents can be substituted for elements thereof without departing from the scope of the invention, and features mentioned in the various embodiments can be combined in any way as long as there is no structural conflict, and any reference sign in the claims should not be construed as limiting the claim concerned, and the embodiments should be regarded as being exemplary and non-limiting in any way whatsoever. Therefore, all technical solutions that fall within the scope of the claims are within the scope of the present invention.

Claims (3)

1. The structure for increasing the dynamic pressure of the sliding pair is characterized by comprising two friction bodies which move relatively, a liquid film is formed between the friction bodies, and a plurality of rectangular textures are arranged at the opposite ends of the friction bodies, wherein the friction bodies are provided with a plurality of rectangular textures, and the friction bodies are arranged on the surfaces of the friction bodiesOne point on the opposite side of the body is the origin of the texture, the length of which is l_xAnd the radian of the length corresponding to the x axis is alpha_kWidth of texture is l_yWidth of radian beta corresponding to y-axis_kHeight of texture h_kSaid α is_kThe radian of the beta-radian measure is-5000 to 5000 mu rad_kThe radian range of the arc is-5000 to 5000 mu rad, and h is_kThe length of the glass is-5 to 5 μm.

2. The structure for increasing the dynamic pressure of a sliding pair as claimed in claim 1, wherein when said α is_k，β_kAnd h_kWhen the value of (A) is a positive value, the texture is pit type; when the alpha is_k，β_kAnd h_kWhen the value of (a) is negative, the texture is a boss type; the texture near the inlet area of the liquid film is pit-type, and the texture near the outlet of the liquid film is boss-type.

3. The structure for increasing the dynamic pressure of a sliding pair as claimed in claim 2, wherein the distribution range of the crater-like texture is in an inverted U-shape, and the highest point of the boss is entirely biased toward the central region of the liquid film.

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