Design method of non-equal-depth micro-texture piston pin shaft

Abstract

The invention discloses a design method of a non-equal-depth micro-texture piston pin shaft. A sequential coupling method is adopted to simulate the contact condition of a piston pin hole-pin shaft contact area under the influence of a thermal load and a mechanical load, an adhesion area and a sliding area in the pin hole and pin shaft contact part are obtained through analysis, the deformation of the adhesion area and the deformation of the sliding area are solved, the non-equal-depth micro-texture of the piston pin shaft is designed based on the deformation of the adhesion area and the deformation of the sliding area, and the non-equal-depth micro-texture of the piston pin shaft is obtained. And finally, the designed non-equal-depth micro-texture of the piston pin shaft is machined. The bearing characteristic of a lubricating oil film in the contact area of the piston pin shaft and the piston pin hole can be improved, the micro-texture of the contact area is designed in a non-equal depth mode, different amounts of lubricating oil are stored in the area, dry friction between the piston pin shaft and the pin hole due to factors such as deformation of the piston pin hole is effectively avoided, and the service life of the piston pin shaft is prolonged. Friction loss between the pin shaft and the piston is reduced, and the service life of the piston pin shaft is prolonged.

Description

Technical Field

[0001] The present invention belongs to the field of piston pin processing and relates to a non-uniform depth micro-texture piston pin design method, which can be applicable to various types of internal combustion engine piston pins, can effectively avoid dry friction between the piston pin and the pin hole caused by factors such as piston pin hole deformation, increase lubrication between the piston and the pin, and reduce friction loss. Technical Background

[0002] (1) In the actual working process of the piston, due to the influence of multiple field coupling conditions such as gas pressure and thermal load, its actual lubrication state is very complex. As the piston pin and pin hole deform under mechanical and thermal loads, irregular concave and convex areas are formed on the contact surface between the two, resulting in discontinuity and breakage of the lubricating oil film, and then boundary friction or even dry friction occurs. At the same time, plastic deformation and shearing occur at the contact position of the piston pin and pin hole, which aggravates adhesive wear, deteriorates the lubrication state of the piston pin-pin hole friction pair, and finally leads to piston failure. Therefore, it is necessary to optimize the lubrication state between the piston pin shaft and the piston pin hole.

[0003] (2) Surface texturing technology is a technology that uses physical, chemical or mechanical methods to artificially process micron-scale structures on the surface of the friction pair. When the friction pair is in boundary lubrication, the pit structure of the surface micro-texture can store solid particles on the surface of the friction pair to a certain extent, reducing the damage to the friction pair. Secondly, the lubricating oil stored in the micro-texture pits can be brought to the friction contact surface to lubricate the friction pair. Finally, when the friction pair is in dynamic pressure lubrication, the micro-texture generates additional dynamic pressure on the surface of the friction pair, which improves the bearing capacity of the friction pair and reduces its friction coefficient.

[0004] (3) The rapid development of laser technology has enabled laser drilling technology to be realized and applied in the industrial field. Compared with traditional mechanical drilling, electric spark machining and other methods, laser drilling can perform high-precision and high-efficiency drilling on materials with high hardness and high melting point without tool loss, and is suitable for batch and high-density group hole processing. Summary of the invention

[0005] The present invention aims to reduce the dry friction between the piston pin and the pin hole caused by the deformation of the piston pin hole and other factors during the actual operation of the internal combustion engine, and reduce the friction loss between the pin and the piston. A non-equal depth micro-texture design method is provided. By texturing the contact area between the piston pin and the piston pin hole, the area can be guaranteed to have sufficient oil supply under different deformation amounts of the piston pin hole, thereby improving the lubrication between the pin and the piston, achieving the purpose of reducing the friction loss between the pin and the piston and extending the service life of the piston pin.

[0006] The technical solution of the present invention is: a design method for a non-uniform depth micro-textured piston pin, characterized in that it comprises the following steps:

[0007] 1. A design method for a piston pin with non-equal depth micro-texture, characterized in that a sequential coupling method is used to simulate the contact condition of a piston pin hole-pin contact area under the influence of thermal load and mechanical load, an adhesion zone and a sliding zone in the contact part between the pin hole and the pin are analyzed, and the deformation of the adhesion zone and the sliding zone is solved. Based on the deformation of the adhesion zone and the sliding zone, a non-equal depth micro-texture of the piston pin is designed, and finally a piston pin with non-equal depth micro-texture is obtained by processing, comprising the following steps:

[0008] (1) Establish a geometrically symmetric model of the piston-pin shaft, divide the computational grid, add material properties and thermal boundary conditions, define the piston pin hole-pin shaft contact area as friction contact, and calculate the steady-state temperature field of the piston-pin shaft;

[0009] (2) Using the sequential coupling method, the piston mechanical load boundary conditions are set to calculate and obtain the piston-pin "thermal-mechanical coupling" model under steady-state conditions;

[0010] (3) Based on the piston-pin "thermal-mechanical coupling" model, the contact state between the piston pin hole and the pin is analyzed, and the distribution of the sliding area and the adhesion area in the contact area between the piston pin hole and the pin is obtained;

[0011] (4) Calculate the deformation of the sliding area and the adhesion area, divide the sliding area and the adhesion area into n arc surfaces, and number the obtained arc surfaces X1, X2, ...X n The corresponding annular surfaces of each arc surface on the piston pin are Z1, Z2...Z n , the distance between the center lines of adjacent arc surfaces is d1, and the maximum deformation corresponding to each arc surface is defined as Y1, Y2...Y n ;

[0012] (5) With arc surface X1, X2...X n The maximum deformation Y1, Y2...Y n Based on this, the micro texture of each arc surface corresponding to the annular surface on the piston pin is designed, and the annular surfaces Z1, Z2...Z n The texture depth is H1, H2...H n , the designed micro texture is uniformly surrounded by the annular surface Z1, Z2...Z of the pin shaft at the same central angle θ n , so that the piston pin surface is covered with non-uniform depth micro-texture, where R is the radius of the pin, θ is the central angle corresponding to the geometric centers of two adjacent micro-textures on the same annular surface;

[0013] (6) The micro-texture designed in the laser processing step (5) is applied to each corresponding annular surface on the piston pin to obtain a piston pin having a non-uniform depth micro-texture, that is, a design method for a non-uniform depth micro-texture piston pin is obtained.

[0014] 2. A method for designing a non-uniform depth micro-textured piston pin according to claim 1, characterized in that: in the step (5), the maximum deformation Y1, Y2, ...Y n The average value of The micro texture depth corresponding to this value is defined as H, and the formula is Calculate the annular surfaces Z1, Z2...Z of the pin shaft respectively n Texture depth H1, H2...H n .

[0015] 3. A method for designing a piston pin with non-uniform depth micro-texture according to claim 1, characterized in that: in the step (4), the midline spacing d1 of each arc surface is 400-800 μm.

[0016] 4. A method for designing a piston pin with non-uniform depth micro-texture according to claim 1, characterized in that: the geometric center of the non-uniform depth micro-texture in step (5) is located on the midline of each annular surface.

[0017] 5. A method for designing a piston pin with non-uniform depth micro-texture according to claim 1, characterized in that the appearance of the non-uniform depth micro-texture in step (5) is circular pits, regular triangular pits, regular hexagonal pits, or one or more combinations thereof.

[0018] 6. A design method for a non-uniform depth micro-textured piston pin according to claim 2, characterized in that: the maximum deformation of each arc surface Y1, Y2...Y n The average The corresponding texture depth H is 40 to 60 μm.

[0019] According to the design method of a non-uniform depth micro-textured piston pin described in claim 3, it is characterized in that the radius of the circular pit is 100-200 μm, the side length of the regular triangle is 135-191 μm, and the side length of the regular hexagon is 55-110 μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The piston model selected for the present invention;

[0021] Figure 2 is the piston mechanical load distribution diagram;

[0022] Figure 3Schematic diagram of the sliding area and adhesion area of ​​the piston pin control in the simulation;

[0023] Figure 4 Schematic diagram of piston pin controlled sliding area and adhesion area, where X1, X2...X n is the arc surface selected at the piston pin hole, d1 is the distance between the center lines of adjacent arc surfaces;

[0024] Figure 5 This is the side view of the pin shaft, in which Z1, Z2...Z n Arc surface X1, X2...X selected for pin hole n The torus d1 on the corresponding pin is the distance between the center lines of adjacent torus;

[0025] Figure 6 It is the front view of the pin, in which H1, H2...Hn are the depths of micro texture;

[0026] Figure 7 It is a side view of the pin shaft, where θ is the central angle corresponding to the geometric centers of two adjacent micro-textures on the same annular surface. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] (1) A geometrically symmetrical model of the piston-pin shaft was established, and the computational mesh of the model was divided using Hypermesh. The mesh size of the contact area between the piston pin shaft and the pin hole was 0.5 mm. The model was imported into the steady-state thermal module of Ansys workbench to set the material properties and thermal boundary conditions. The contact area between the piston pin hole and the pin shaft was defined as friction contact, and the friction coefficient was set to 0.02. The steady-state temperature field of the piston-pin shaft was calculated. The calculation results of the steady-state temperature field of the piston were imported into the static structure module using the sequential coupling method. The mechanical load boundary conditions of the piston were set. The load on the top surface of the piston was 18 MPa, and the loads on the remaining parts were as follows: Figure 2 As shown in the figure, the piston-pin "thermal-mechanical coupling" model under steady-state conditions is calculated and obtained; based on the piston-pin "thermal-mechanical coupling" model, the contact state of the piston pin hole and the pin is analyzed, and the distribution of the sliding area and the adhesion area in the contact part between the piston pin hole and the pin is obtained as shown in the figure. Figure 3 As shown;

[0029] (2) The piston pin hole sliding and adhesion area is divided into n arc surfaces, and the obtained arc surfaces are numbered X1, X2...X n ,like Figure 4 As shown in the figure, the circular surfaces on the pin shaft corresponding to the arc surface of the pin hole are numbered Z1, Z2...Z n The center line spacing is d1 = 600 μm. Figure 5As shown, the maximum deformation corresponding to each annular surface is Y1, Y2...Y n , calculate the maximum deformation Y1, Y2...Y corresponding to each annular surface n The average value of The texture depth corresponding to this value is defined as H = 50 μm, and the formula Calculate the torus X1, X2...X n Corresponding texture depths H1, H2...H n like Figure 6 As shown;

[0030] (3) The appearance of the non-uniform depth micro-texture is designed to be a circular pit with a diameter of 150 μm. n The corresponding microtexture is at an equal central angle θ = 0.3°. Figure 7 As shown, it is uniformly surrounded by the torus X1, X2...X n The geometric center of the circular pit is located on the midline of the torus.

[0031] (4) The non-equal depth micro-texture designed in step (5) is prepared on the contact area between the piston pin and the piston pin hole on the piston pin by laser processing. The laser processing adopts HGTECH-LG20 nanosecond fiber laser marking machine with an emission wavelength of 1000nm, a maximum average power of 40W, a repetition frequency of 30-60kHz, and a pulse repetition number of 5-7 times. The obtained piston pin is a piston pin with non-equal depth micro-texture.

[0032] (5) The present invention is not limited to the above-mentioned embodiments. Any person should be aware that any technical solution identical or similar to the present invention made under the inspiration of the present invention shall fall within the protection scope of the present invention.

[0033] (6) The techniques, shapes, and structures not described in detail in the present invention are all known technologies.

Claims

1. A design method for a non-uniform depth micro-textured piston pin, characterized in that: The sequential coupling method is used to simulate the contact conditions of the piston pin hole-pin shaft contact area under the influence of thermal load and mechanical load, and the adhesion area and sliding area in the contact part of the pin hole and the pin shaft are analyzed. The deformation of the adhesion area and the sliding area is solved, and the non-equal depth micro-texture of the piston pin shaft is designed based on the deformation of the adhesion area and the sliding area. Finally, a piston pin shaft with non-equal depth micro-texture is obtained by processing, including the following steps: (1) Establish a geometrically symmetric model of the piston-pin shaft, divide the computational grid, add material properties and thermal boundary conditions, define the piston pin hole-pin shaft contact area as friction contact, and calculate the steady-state temperature field of the piston-pin shaft; (2) Using the sequential coupling method, the piston mechanical load boundary conditions are set to calculate and obtain the piston-pin "thermal-mechanical coupling" model under steady-state conditions; (3) Based on the piston-pin "thermal-mechanical coupling" model, the contact state of the piston pin hole and the pin is analyzed, and the distribution of the sliding area and the adhesion area in the contact area between the piston pin hole and the pin is obtained; (4) Calculate the deformation of the sliding area and the adhesion area, divide the sliding area and the adhesion area into n arc surfaces, and number the obtained arc surfaces X1, X2, ...X n The corresponding annular surfaces of each arc surface on the piston pin are Z1, Z2...Z n , the distance between the center lines of adjacent arc surfaces is d1, and the maximum deformation corresponding to each arc surface is defined as Y1, Y2...Y n ; (5) With arc surface X1, X2...X n The maximum deformation Y1, Y2...Y n Based on this, the micro texture of each arc surface corresponding to the annular surface on the piston pin is designed, and the annular surfaces Z1, Z2...Z n The texture depth is H1, H2...H n , the designed micro texture is uniformly surrounded by the annular surface Z1, Z2...Z of the pin shaft at the same central angle θ n , so that the piston pin surface is covered with non-uniform depth micro-texture, where R is the radius of the pin, θ is the central angle corresponding to the geometric centers of two adjacent micro-textures on the same annular surface; (6) The micro-texture designed in the laser processing step (5) is applied to each corresponding annular surface on the piston pin to obtain a piston pin having a non-uniform depth micro-texture, that is, a design method for a non-uniform depth micro-texture piston pin is obtained.

2. A method for designing a non-uniform depth micro-textured piston pin according to claim 1, characterized in that: In the step (5), the maximum deformation Y1, Y2, ...Y n The average value of The micro texture depth corresponding to this value is defined as H, and the formula is Calculate the annular surfaces Z1, Z2...Z of the pin shaft respectively n Texture depth H1, H2...H n .

3. A method for designing a non-uniform depth micro-textured piston pin according to claim 1, characterized in that: In the step (4), the distance d1 between the center lines of the arc surfaces is 400 to 800 μm.

4. A method for designing a non-uniform depth micro-textured piston pin according to claim 1, characterized in that: The geometric center of the non-uniform depth micro-texture in step (5) is located on the midline of each annular surface.

5. A method for designing a non-uniform depth micro-textured piston pin according to claim 1, characterized in that: The appearance of the non-uniform depth micro-texture in step (5) is circular pits, regular triangle pits, regular hexagonal pits, or one or more combinations thereof.

6. A method for designing a non-uniform depth micro-textured piston pin according to claim 2, characterized in that: The maximum deformation of each arc surface Y1, Y2...Y n The average The corresponding texture depth H is 40 to 60 μm. A method for designing a non-uniform depth micro-textured piston pin according to claim 3, characterized in that: The radius of the circular pit is 100-200 μm, the side length of the regular triangle is 135-191 μm, and the side length of the regular hexagon is 55-110 μm.

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