CN105221283B - A kind of engine cylinder hole and its processing method - Google Patents

Abstract

The invention provides an engine cylinder hole and a processing method thereof. The surface of the cylinder hole is distributed with an array of cavities; the size of the cavities is on the micron scale; shift angle α∈[30,90]°, the distribution density of the concave cavity (10) ρ∈[5,20]%; the concave cavity has Different spacing, that is, keep the circumferential spacing M constant, increase the axial N spacing, perform high-density micro-cavity morphology processing in the high-speed area, and perform low-density micro-cavity morphology processing in the low-speed area; by changing The density of the concave cavities reduces the number of the concave cavities, obtains the mirror cylinder bore through mechanical honing, and then processes the surface of the cylinder bore with a laser to obtain a circular concave cavity array with a special uniform distribution law and a size of micron. ; During the relative movement of the cylinder bore-piston ring, the concave cavity forms a continuous lubricating oil film with the least lubricating oil loss, and exerts the fretting pressure lubrication effect.

Description

A kind of engine cylinder bore and processing method thereof

technical field

The invention belongs to the field of internal combustion engines, and in particular relates to an engine cylinder hole and a processing method thereof.

Background technique

The cylinder bore-piston ring friction pair is one of the typical friction pairs in the engine, which determines the service performance and life of the engine, and the texture structure of the cylinder bore surface is closely related to the engine emission performance. In the past, the mechanical honing process was generally used in the machining of engine cylinder bores. By reducing the roughness of cylinder bores and forming cross-platform textures, the lubrication conditions between cylinder bores and piston ring friction pairs were improved. In recent years, with the advancement of special processing, especially high-energy laser processing technology, cylinder bore laser texturing technology has emerged. It has the advantages of energy saving and emission reduction, efficient processing, no tool loss and environmental friendliness, and has attracted the attention of the industry.

CN200510116292 discloses a laser honing tool for processing micro-groove structures on the surface of a workpiece bearing friction load. This patent does not propose the surface requirements of the cylinder bore before machining, but in fact it is very critical, and the selection of the laser machining position in this patent does not consider the wear distribution of the cylinder bore surface, which is not targeted enough. In addition, the size of the microgroove structure in this patent is too large to form the fretting pressure lubrication effect.

Different from the laser honing technology mentioned in the above-mentioned laser, the cylinder bore laser texturing technology is to process a large number of circular micro-cavity arrays with precisely controllable density, distribution and depth on the cylinder bore surface. CN201310266008 discloses a cylinder bore processing method, which includes pre-processing, surface texture, post-processing and detection. This patent performs laser micro-texture processing on the surface of the cylinder bore in subregions. However, the setting of the subregions does not combine the actual working conditions of the engine and the relative movement between the cylinder bore and the piston ring. Therefore, in this method, the microdimples are evenly distributed in the axial and circumferential directions of the cylinder bore.

The friction pair between the engine cylinder bore and the piston ring has remarkable characteristics: on the one hand, it has eccentric wear, and the wear conditions of different areas of the cylinder bore are different, and it is easy to occur in the top dead center area and the area in contact with the piston skirt Wear and tear will affect the performance and life of the engine. Furthermore, it has variable speed characteristics. At different stroke positions, the surface of the cylinder bore and the piston ring have different relative speeds and accelerations, so the stress conditions are also different. Finally, it also has the inhomogeneity of the temperature field distribution, and the temperature is higher near the combustion chamber and the top dead center.

Contents of the invention

The purpose of the present invention is to solve the deficiencies in the prior art, and provide a kind of engine cylinder bore and its processing method, solve the problem of low processing efficiency, easy to appear due to the surface support rate The problem of wear and poor emission performance caused by the drop.

The technical solution of the present invention is: a kind of engine cylinder hole, the surface of described cylinder hole is distributed with concave cavity array; The size of described concave cavity is micrometer scale; Equal to 0.2μm;

The initial positions of the concave cavities in different rows are offset, and the line connecting the initial positions of the concave cavities in all rows is the initial position line; the angle formed by the intersection of the initial position line with the cylinder bore circumference is An offset angle α, the offset angle α∈[30,90]°.

In the above solution, the contour of the cavity is circular, the diameter of the cavity is R∈[10,300]μm, and the depth of the cavity is H∈[2,20]μm.

In the above scheme, the distribution density of the concave cavity in the cylinder bore ρ∈[5,20]%; the distribution density ρ=π×[cavity diameter R] ² /[4×sin offset angle α× Axial spacing N×circumferential spacing M]×100%.

In the above solution, the surface of the cylinder bore is divided into a non-processing area, area A, area B and area C;

The non-processing area is the non-contact area between the cylinder bore and the piston ring during engine operation;

The area A is the area near the top dead center line, and the length LA of the area A is 5%-15% of the _total length _L of the cylinder bore;

The area B is the contact area between the primary and secondary thrust surfaces of the piston and the surface of the cylinder bore;

The area C is the area between the bottom dead center line and the area A except the area B;

The distribution densities of the concave cavities in the region A, the region B and the region C are ρ _A , ρ _B , and ρ _C respectively, and the size arrangement is: ρ _A ≥ ρ _B ≥ ρ _C .

Further, the distribution densities of the cavities in the region A, the region B and the region C are respectively: 15% _≤ρA≤20 %, 10% _≤ρB≤15 %, 5%≤ _ρC ≤ 10%.

Further, the axial spacing N of the concave cavities increases axially along the cylinder bore, and the distribution density of the concave cavities in the area A, the area B or the area C ranges from the upper part of each area to the The lower difference is 3%-10%.

A processing method for the engine cylinder bore, comprising the following steps:

S1: Pretreatment, the front surface is processed by mechanical honing to smooth the texture;

S2: surface texture, using a focused laser beam to process the concave cavity array on the surface of the cylinder bore;

S3: Post-processing, using mechanical polishing to clean the textured surface.

In the above scheme, the specific process of mechanical honing in the step S1 is as follows: first use a diamond honing stick to remove the margin, and then use a cork strip to smooth the surface before the texture processing; the surface parameter range of the surface before the texture processing is Rpk ≤0.2μm, Rk≤0.4μm, Rvk≤1.0μm.

In the above scheme, in the step S2, the single pulse energy of the focused laser beam is 0.5-2.5mJ;

The focused laser beam is processed from the upper part of the cylinder bore to the lower part. At the initial moment of the area A, the area B or the area C, the numerical control system records the first laser pulse acting on the axis of the cylinder bore surface direction and circumferential position;

After processing a row of concave cavities with equal circumferential spacing M, the numerical control system controls the focused laser beam to act on the first pulse acting position of the next row, and its axial position is the axial position of the first pulse acting on the previous row plus two The axial spacing N between the rows, its circumferential position is the circumferential position of the first pulse laser pulse in the previous row plus an offset, and the processing logic of the concave cavity array in the subsequent row is the same; the offset is The axial distance between this row and the previous row is N×[tan offset angle α].

In the above solution, the specific post-treatment process in step S3 is as follows: first use a diamond honing stick to remove excess, and then use a cork strip to smooth the textured surface; the textured surface Rpk≤0.3 μm.

Compared with the prior art, the present invention has the following beneficial effects:

1. According to the wear and speed characteristics of the cylinder bore-piston ring friction pair, combined with the variation of the distribution density of the cavity in the axial direction of the cylinder hole and the circumferential direction of the cylinder hole, the minimum amount of the cavity The processing of the topography forms a continuous lubricating oil film and fretting pressure lubrication effect on the surface of the cylinder bore.

2. In the present invention, the concave cavity has different spacings in the axial direction of the cylinder bore and the circumferential direction of the cylinder bore respectively, that is, keeping the circumferential spacing M constant and increasing the axial spacing N, thereby changing the cylinder The cavity density of the hole surface reduces the machining of the cavity topography.

3. The present invention also correlates the distribution density of the cavity in the axial direction of the cylinder hole with the relative movement speed of the cylinder hole-piston ring, and performs high-density processing of the cavity shape in the high-speed region, and in the low-speed region Low-density machining of the cavity topography is performed such that ρ _A ≥ ρ _B ≥ ρ _C .

4. The present invention obtains a mirror surface cylinder bore through mechanical honing, and then processes a laser on the surface of the cylinder bore to obtain a circular concave cavity array with a special uniform distribution law and a size of micron; the concave cavity is formed between the cylinder bore-piston ring During the relative movement, a continuous lubricating oil film is formed with the least loss of lubricating oil, and the fretting pressure lubrication effect is exerted.

5. The present invention improves production efficiency and reduces processing energy consumption by reducing the processing amount of the cavity shape.

6. The present invention reduces the volume of the hollow body formed by the concave cavity on the surface of the cylinder bore, thereby reducing the evaporation of engine oil on the surface of the cylinder bore. For the complete engine, the fuel consumption is reduced by about 4-5%, and the oil consumption is reduced by 30-30%. 50% or so, ultimately improving emission performance.

7. The present invention greatly increases the surface support rate by reducing the volume of the hollow body on the surface of the cylinder bore, reduces the pressure on the contact surface of the cylinder bore surface and the piston ring, thereby reducing wear.

8. Although the number of the concave cavities is reduced in the present invention, their effects on lubricating and reducing friction on the surface of the cylinder bore are not significantly weakened.

Description of drawings

Fig. 1 is a schematic diagram of a cylinder hole in an embodiment of the present invention.

Fig. 2 is a schematic diagram of a sectioned and flattened cylinder bore in an embodiment of the present invention.

Fig. 3 is a schematic diagram of a local concave cavity array in an embodiment of the present invention.

In the figure, 1. Cylinder bore; 2. Cylinder bore axial direction; 3. Cylinder bore circumferential direction; 4. Non-processing area; 5. Top dead center line; 6. Bottom dead center line; 7. Area A; 8. Area B; 9, area C; 10, cavity; 11, initial position line.

detailed description

The present invention will be described in further detail below in conjunction with the specific embodiments of the accompanying drawings, but the protection scope of the present invention is not limited thereto.

Fig. 1 shows a schematic diagram of a cylinder bore 1 in an embodiment of the present invention, a cylinder bore of an engine, the surface of the cylinder bore 1 is distributed with an array of cavities 10, the size of the array of cavities 10 is on the micron scale, and the cylinder bore 1 The surface roughness Ra value of the non-recessed cavity 10 is less than or equal to 0.2 μm. The surface of the cylinder hole 1 of the present invention is smoother, so that the oil scraping effect of the oil ring in the piston ring is improved during the operation of the engine, and at the same time, the increase of the oil consumption of the whole machine caused by the evaporation of the oil on the surface of the cylinder hole 1 is reduced.

Fig. 2 shows a schematic diagram of a cut and flattened cylinder bore 1 in an embodiment of the present invention, defining the circumferential direction of the cylinder bore 1 as the cylinder bore circumferential direction 3; the central axis direction of the cylinder bore 1 as the cylinder bore axial direction 2 . Then, the spacing of the array of concave cavities 10 in the circumferential direction 3 of the cylinder bore is the circumferential spacing M, and the spacing of the array of concave cavities 10 in the axial direction 2 of the cylinder bore is the axial spacing N.

Fig. 3 is a schematic diagram of a local concave cavity array in an embodiment of the present invention, the cylinder bore circumferential direction 3 is also the row direction of the concave cavity 10 array; the initial positions of the concave cavities 10 in different rows are offset, The line connecting the initial positions of all rows is the initial position line 11, and the angle formed by the initial position line 11 and the cylinder bore circumferential direction 3 is an offset angle α, and the offset angle α∈[30,90]° .

In this embodiment, the profile of the cavity 10 shown is preferably circular, with a diameter ∈ [10,300] μm, a depth ∈ [2,20] μm, and an offset angle α ∈ [45,90]°.

Further define the distribution density of the cavity 10 at a certain position on the surface of the cylinder bore 1 ρ=π×[cavity diameter] ² /[4×sin offset angle α×axial spacing N×circumferential spacing M]×100 %; the distribution density ρ∈[5,20]% of the concave cavities 10 at any position on the surface of the cylinder bore 1, the distribution density ρ of the concave cavities 10 in a certain area on the surface of the cylinder bore 1 and the area in The positions of the cylinder bore circumferential direction 3 and the cylinder bore axial direction 2 are related.

As shown in FIG. 2 , the _total length L of the cylinder bore 1 is 150 mm, and the diameter of the cylinder bore 1 is 73 mm. The surface of the cylinder bore 1 is divided into a non-processing area 4, an area A7, an area B8 and an area C9. Wherein, the non-processing area 4 is the non-contact area between the cylinder bore 1 and the piston ring during the operation of the engine, and the length L of the _non -processing area 4 is not; the area A7 is the area near the top dead center line 5, The length LA of the area A7 is 5%-15% of the _total length _L of the cylinder hole 1; the area B8 is the contact area between the main and secondary thrust surfaces of the piston and the surface of the cylinder hole 1, and the length of the area B8 is L _B , the width is W _B ; the area C9 is the area between the bottom dead center line 6 and the area A7 excluding the area B8, the length of the area C9 is L _C , and the width is W _C .

The distribution densities of the cavities 10 in the region A7, the region B8 and the region C9 are respectively ρ _A , ρ _B , and ρ _C , and the sizes of the ρ _A , the ρ _B , and the ρ _C are The arrangement has the following distribution law: ρ _A ≥ ρ _B ≥ ρ _C , and the axial spacing N increases along the cylinder bore axis 2, so that the cavity 10 is in the area A7, the area B8 or the The distribution density in the region C9 varies from 3% to 10% from the upper part to the lower part of each region; the maximum distribution density of the concave cavities 10 in each region is the distribution density of the concave cavities 10 in each region. In this embodiment, the distribution density of the cavities 10 in the region A7, the region B8 and the region C9 is preferably: 15%≤ρ _A ≤20%, 10%≤ρ _B ≤15% , 5% _≤ρC≤10 %.

A method for the engine cylinder bore is divided into the following three steps:

S1: Use mechanical honing to smooth the texture before processing the surface. The specific process is to first use a diamond honing stick to remove the margin, and then use a cork strip to smooth the texture before processing the surface; the surface parameter range of the texture before processing the surface is Rpk ≤0.2μm, Rk≤0.4μm, Rvk≤1.0μm.

S2: Processing the array of concave cavities 10 on the surface of the cylinder bore 1 with a focused laser beam, the specific process is that the single pulse energy of the focused laser beam is 0.5-2.5mJ;

The focused laser beam is processed from the upper part of the cylinder bore 1 to the lower part. At the initial moment of the area A7, the area B8 or the area C9, the numerical control system records the first laser pulse acting on the surface of the cylinder bore 1. Axial and circumferential position;

After processing a row of concave cavities 10 with equal circumferential spacing M, the numerical control system controls the focused laser beam to act on the first pulse action position of the next row, and its axial position is the axial position of the first pulse action of the previous row plus The axial distance N between two rows, its circumferential position is the circumferential position of the first pulse laser pulse in the previous row plus an offset, the processing logic of the concave cavity 10 in the subsequent row is the same, and the offset It is the axial spacing N×tan (offset angle α) between this row and the previous row.

S3: Mechanical polishing is used to clean the textured surface. The specific process is to first use a diamond honing stick to remove the margin, and then use a cork strip to smooth the textured surface so that the textured surface Rpk≤0.3 μm.

According to the wear and speed characteristics of the cylinder hole-piston ring friction pair, the present invention combines the changes in the distribution of the cavity 1 in the axial direction 2 of the cylinder hole and the circumferential direction 3 of the cylinder hole to achieve the minimum amount of the cavity 1, forming a continuous lubricating oil film and fretting pressure lubrication effect on the surface of the cylinder bore 1. Compared with the prior art, the method for reducing the topography processing of the cavity 1 in the present invention is: changing the topography density of the cavity 1 on the surface of the cylinder bore 1 is divided into two ways: one, the The shape of the concave cavity 1 has different spacings in the axial direction 2 and the circumferential direction 3, that is, keep the circumferential spacing M constant and increase the axial spacing N; secondly, the shape of the concave cavity 1 The distribution density in the axial direction of the cylinder bore 2 is related to the relative motion speed of the cylinder bore-piston ring, the high-density topography processing of the concave cavity 1 is performed in the high-speed area, and the low-density topography processing is performed in the low-speed area. Topography processing of cavity 1.

The described embodiment is a preferred implementation of the present invention, but the present invention is not limited to the above-mentioned implementation, without departing from the essence of the present invention, any obvious improvement, replacement or modification that those skilled in the art can make Modifications all belong to the protection scope of the present invention.

Claims (8)

1. a kind of engine cylinder hole, it is characterised in that cylinder holes (1) surface distributed has cavity (10) array；The cavity (10) size is micro-meter scale；The regional roughness Ra values of the non-cavity in cylinder holes (1) surface (10) are less than or equal to 0.2 μ m；

Skew, the company of initial position of the cavity (10) in all rows be present in the initial position do not gone together in the cavity (10) Line is initial position line (11)；It is deviation angle α that the initial position line (11) intersects angulation with cylinder holes circumferential (3), The deviation angle α ∈ [30,90] °；

Distribution density ρ ∈ [5,20] % of the cavity (10) in the cylinder holes (1)；Distribution density ρ=the π × [cavity is straight Footpath R]²/ [4 × sin deviation angles α × axial spacing N × circumferential spacing M] × 100%；

Cylinder holes (1) surface is divided into non-processing region (4), region A (7), region B (8) and region C (9)；

The non-processing region (4) is the cylinder holes (1) and piston ring relief area in engine operation process；

The region A (7) is top dead centre line (5) close region, the length L of the region A (7)_AFor the cylinder holes (1) overall length L_Always 5%-15%；

The region B (8) is piston primary and secondary thrust face and the cylinder holes (1) surface area contact；

The region C (9) removes the region of the region B (8) between lower dead center line (6) and the region A (7)；

Distribution density of the cavity (10) in the region A (7), the region B (8) and the region C (9) is respectively ρ_A、 ρ_B、ρ_C, size is arranged as：ρ_A≥ρ_B≥ρ_C。

2. engine cylinder hole according to claim 1, it is characterised in that the profile of the cavity (10) is circle, described The diameter R ∈ [10,300] μm of cavity (10), the depth H ∈ [2,20] μm of the cavity (10).

3. engine cylinder hole according to claim 1, it is characterised in that the cavity (10) is in the region A

(7), the distribution density in the region B (8) and the region C (9) is respectively：15%≤ρ_A≤ 20%, 10%≤ρ_B≤ 15%, 5%≤ρ_C≤ 10%.

4. engine cylinder hole according to claim 1, it is characterised in that the axial spacing N of the cavity (10) is along cylinder holes Axially (2) are incremented by, distribution density of the cavity (10) in the region A (7), the region B (8) or described region C (9) It is 3%-10% from the top in each region to bottom difference.

5. the processing method of engine cylinder hole described in a kind of claim 1, it is characterised in that comprise the following steps：

S1：Pre-treatment, preceding surface is processed using the smooth texture of mechanical honing；

S2：Surface Texture, using focusing laser beam in cavity (10) array described in the cylinder holes (1) Surface Machining；

S3：Post processing, using surface after mechanical polishing cleaning texture processing.

6. processing method according to claim 5, it is characterised in that mechanical honing concrete technology is in the step S1： Surplus is gone using diamond hone stone first, preceding surface is then processed using the smooth texture of spline；The texture processing The surface parameter scope on preceding surface is Rpk≤0.2 μm, Rk≤0.4 μm, Rvk≤1.0 μm.

7. processing method according to claim 5, it is characterised in that in the step S2, the list for focusing on laser beam Pulse energy is 0.5-2.5mJ；

The focusing laser beam is processed from the cylinder holes (1) top toward bottom, in the region A (7), the region B (8) or institute The initial time of region C (9) is stated, digital control system records axial direction and the week that first laser pulse acts on the cylinder holes (1) surface To position；

After cavity described in a line (10) being machined with equal circumferential spacing M, the digital control system control focusing laser beam effect In the first impulse action position of next line, its axial location is that the first impulse action axial location of lastrow adds two in the ranks Axial spacing N, its circumferential position add offset for the circumferential position of the first pulse laser impulse action of lastrow, subsequent rows The processing logic of cavity (10) array is identical；The offset is axial spacing N × [tan skews of the row and lastrow Angle [alpha]].

8. processing method according to claim 5, it is characterised in that the concrete technology post-processed in the step S3 is： Surplus is gone using diamond hone stone first, then using surface after the smooth texture processing of spline；The texture processing Surface Rpk≤0.3 μm afterwards.