CN113417754B - Wear-resistant structure for aluminum-based piston skirt and machining method thereof - Google Patents

Wear-resistant structure for aluminum-based piston skirt and machining method thereof Download PDF

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Publication number
CN113417754B
CN113417754B CN202110834237.XA CN202110834237A CN113417754B CN 113417754 B CN113417754 B CN 113417754B CN 202110834237 A CN202110834237 A CN 202110834237A CN 113417754 B CN113417754 B CN 113417754B
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wear
piston
aluminum
piston skirt
hexagon
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CN113417754A (en
Inventor
王浩伟
汪明亮
陈东
夏存娟
吴一
王鹏举
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Anhui Xiangbang Composite Material Ltd
Shanghai Jiaotong University
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Anhui Xiangbang Composite Material Ltd
Shanghai Jiaotong University
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/04—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to gases
    • B05D3/0486—Operating the coating or treatment in a controlled atmosphere
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/08—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by flames
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/20—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by magnetic fields
    • B05D3/207—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by magnetic fields post-treatment by magnetic fields
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/0084—Pistons  the pistons being constructed from specific materials

Abstract

The invention provides a wear-resistant structure for an aluminum-based piston skirt and a machining method thereof. Wear-resisting structure includes the arch that a plurality of rule was arranged, and bellied rule of arranging is: the surface of the piston skirt part is repeatedly extended by the same virtual hexagon, each hexagon shares a side with the adjacent hexagon and a vertex, and each vertex is provided with a bulge, wherein the aluminum-based piston is an aluminum alloy piston or an aluminum-based composite material piston. The processing method of the wear-resistant structure comprises the following steps: step 1, processing a bulge on the metal surface of the piston skirt; step 2, processing a fillet on the edge of the top surface of the bulge; and 3, adding a wear-resistant coating on the top surface of the bulge or the whole surface of the piston skirt. The invention has the following beneficial effects: the novel oil collecting and distributing structure is provided, the surface material of the novel oil collecting and distributing structure is subjected to wear-resisting reinforcement treatment, and the lubricity and the service life of the aluminum-based piston can be obviously improved.

Description

Wear-resistant structure for aluminum-based piston skirt and machining method thereof
Technical Field
The invention belongs to the technical field of engines, relates to a piston of an internal combustion engine, and relates to a wear-resistant structure for an aluminum-based piston skirt and a processing method thereof.
Background
An aluminum-based piston generally refers to an aluminum alloy piston or an aluminum-based composite piston, and such a piston is one of the key components of an engine, and a piston skirt plays roles of guiding, bearing side pressure, heat transfer and the like in a cylinder. During the working process of the aluminum-based piston, due to the second-order motion of the piston, the skirt part of the piston is subjected to great side thrust and high-temperature and high-pressure heat load, the skirt part of the piston is deformed, and the phenomena of cylinder biting and cylinder pulling can occur due to the fact that a local gap between the skirt part of the piston and a cylinder sleeve is too small; or the phenomenon of cylinder knocking, increasing engine oil consumption, cylinder sleeve cavitation erosion or overlarge noise and the like can be caused due to overlarge clearance; or after the skirt is deformed, lubrication is difficult to achieve, thereby affecting operational reliability.
The reasonable profile of the skirt part of the piston ensures that the piston obtains good guide and enough bearing area to form enough lubricating oil film so as to reduce friction and abrasion and ensure reasonable clearance of the cylinder under any working condition. Therefore, improvement of the lubrication frictional wear of the skirt portion is an important issue. In order to improve the lubrication of the skirt part, an oil collecting and distributing hole can be processed on the surface of the skirt part. When the abrasion resistance of the piston is improved, surface strengthening treatment is often adopted, such as graphite spraying, molybdenum disulfide spraying, tin plating or lead plating and the like on the surface of the piston.
There is room for further improvement in these existing wear resistant constructions and materials for aluminum-based piston skirts.
Disclosure of Invention
The invention aims to provide a wear-resistant structure for an aluminum-based piston skirt and a processing method thereof, aiming at the problems of how to improve the oil collecting and distributing structure of the aluminum-based piston skirt and the wear resistance of the surface material of the aluminum-based piston skirt.
In order to solve the above technical problem, the object of the present invention can be achieved by the following solutions:
in a first aspect, the present invention provides a wear-resistant structure for an aluminum-based piston skirt, the wear-resistant structure comprising a plurality of protrusions regularly arranged on a surface of the piston skirt; the arrangement rule of the bulges is as follows: the surface of the piston skirt part is repeatedly extended by the same virtual hexagon, each hexagon is shared with the adjacent hexagons and is shared with a vertex, and each vertex is provided with one bulge. The wear-resistant structure protrudes from the surface of the metal substrate and is in principle of the convex texture. The wear-resistant structure is composed of a plurality of regularly arranged bulges. The bulges are arranged in a honeycomb shape. Each lobe is located at an apex with which the geometric center of the lobe cross section coincides.
In some embodiments, the aluminum-based piston comprises an aluminum alloy piston or an aluminum-based composite piston.
In some embodiments, the hexagon is a regular hexagon.
In some embodiments, the hexagons are flattened elongated hexagons.
In some embodiments, the top surface edge of the protrusion is rounded, and the tangent curve of the rounded corner is an elliptical line.
In some embodiments, the sides of the protrusions are straight or curved.
In some embodiments, the top surface of the protrusion is provided as a spherical surface. The top surface of the bulge is designed into a spherical surface, so that lubricating oil can also reach the top surface of the bulge, and the spherical top surface reduces the contact area between the piston and the cylinder wall, thereby further reducing friction. The edge of the top surface of the bulge is provided with a round angle, and the section curve of the round angle is an elliptic line.
In some embodiments, the cross-section of the protrusion is one or more of a combination of a circle, an ellipse, a rounded rectangle, and a rounded triangle.
In some embodiments, the cross-section of the protrusion is circular; the radius of the circle is 1/3-1/2 of the side length of the hexagon.
The arrangement is that the convex parts at the six vertex positions of each regular hexagon enclose a concave part, so that lubricating oil can be retained in the concave part. Moreover, the concave part is not closed, and lubricating oil can freely enter and exit the concave part. And a lubricating oil inlet and outlet is formed between the two bulges on one edge of the hexagon. The access opening must not be too wide, otherwise the time for the lubricant to remain in the recess is too short. Theoretical calculation and experimental verification prove that the radius of the circle is required to be larger than 1/3 of the side length of the regular hexagon. Obviously, the radius of each circle should be smaller than 1/2 of the side length of the regular hexagon, otherwise, two adjacent bulges are connected, and the inlet and outlet of the lubricating oil are eliminated.
In some embodiments, the top surface of the boss or the entire surface of the skirt portion of the piston is provided with a wear resistant coating. The wear-resistant coating is made of graphite or molybdenum disulfide. The thickness of the coating is 10 to 500 μm.
In some embodiments, the wear-resistant coating contains carbon fibers, and the carbon fibers are uniformly distributed in the wear-resistant coating.
In a second aspect, the invention provides an aluminium-based piston, the surface of the skirt portion of which is provided with the above-mentioned wear-resistant structure.
In a third aspect, the invention also provides a method for processing the wear-resisting structure of the aluminum-based piston skirt, which comprises the following steps:
a1, processing bulges on the metal surface of the piston skirt part, wherein the arrangement rule of the bulges is as follows: the surface of the piston skirt part is repeatedly extended by the same virtual hexagon, each hexagon shares a side with the adjacent hexagon and a vertex, and each vertex is provided with one protrusion;
a2, processing a round angle on the edge of the top surface of the bulge;
and A3, adding a wear-resistant coating on the top surface of the bulge or the whole surface of the piston skirt.
In some embodiments, the embossing process of step a1 is produced by a laser ablation, stamping, or etching process. The protrusion can be rapidly and inexpensively machined to form the basic shape of the protrusion by a conventional or advanced manufacturing method.
In a fourth aspect, the present invention further provides a preparation method of the above coating, including the following steps:
and S1, adding magnetic particles on the surface of the carbon fiber to obtain the magnetic carbon fiber.
And S2, adding the magnetic carbon fibers into the graphite, fully and uniformly mixing the magnetic carbon fibers and the graphite, and coating the mixture on the skirt part of the piston to form a coating precursor. In order to sufficiently disperse the magnetic carbon fibers, the carbon fibers and graphite may be put together into a dispersion medium.
And S3, applying a magnetic field outside the piston skirt to make the magnetic carbon fiber migrate to the interior of the coating precursor.
And S4, sintering and solidifying the graphite under the protection of inert gas, wherein the carbon fiber is consolidated.
In some embodiments, the dispersion medium used in step S2 is a liquid that has good wettability with graphite, such as kerosene.
In some embodiments, the application of the magnetic field in step S3 applies ultrasonic oscillations to the piston skirt while rotating the magnetic field about the piston skirt. The ultrasonic oscillation can accelerate the migration of the magnetic carbon fiber.
In some embodiments, the inert gas in step S4 is argon; the sintering temperature is 2000-3500 ℃.
In some embodiments, step S1 includes the following subdivision steps:
s1.1, carrying out ultrasonic treatment on carbon fibers in an acid solution; and (4) carrying out suction filtration, washing with deionized water, and repeating for multiple times until the filtrate is neutral to obtain the carbon fiber after acid washing.
S1.2, fully mixing the carbon fiber after acid washing with an iron ion solution, then dropwise adding an alkaline solution into the iron ion solution until a large amount of precipitate is generated, and standing.
S1.3, removing upper-layer liquid; carrying out suction filtration on the lower-layer precipitate, washing with deionized water, and repeating for multiple times until the filtrate is neutral; thus, magnetic carbon fibers were obtained.
The acid solution in the step S1.1 is obtained by mixing nitric acid and sulfuric acid according to the mass ratio of 1: 1-3: 2. The iron ion solution in step S1.2 is a mixed solution of ferric trichloride solution and ferrous chloride solution, wherein Fe 3+ With Fe 2+ The mass ratio of (A) to (B) is 2: 1-3: 1, in such a ratio, an iron-containing compound having magnetic properties can be produced. When the alkaline solution is dripped, the temperature of the iron ion solution is always kept at 80-90 ℃, which is beneficial to the full precipitation of iron ions.
The surface micro-nano structure arranged according to a certain rule is obtained through active design and manufacturing, namely a pattern array with micro-nano size and arrangement is processed on the surface, so that the surface with a specific function, namely a textured surface, is obtained. The surface texture can be simply divided into two forms of concave texture and convex texture according to the position of the surface texture relative to the surface of the metal substrate.
The concave texture may form a semi-enclosed space, as compared to the convex texture, so that lubricating oil, abrasive dust, abrasive grains, etc. may be more effectively stored. However, the stored abrasive dust, particles, may be deposited inside the concave texture, thereby reducing the effect of the concave texture to some extent. For convex texture, the flow of lubricant will more easily carry away swarf and abrasive particles from the convex texture surface, thereby reducing the deposition similar to that of concave texture. The convex texture and the concave texture have advantages and disadvantages respectively, and the method combines the convex texture and the concave texture, thereby developing the advantages and avoiding the disadvantages.
Compared with the prior art, the invention has the following beneficial effects:
1. the concave texture may form a semi-enclosed space, as compared to the convex texture, so that lubricating oil, abrasive dust, abrasive grains, etc. may be more effectively stored. However, the stored abrasive dust, particles, may be deposited inside the concave texture, thereby reducing the effect of the concave texture to some extent.
2. For convex texture, the flow of lubricant will more easily carry away swarf and abrasive particles from the convex texture surface, thereby reducing the deposition effect similar to that of concave texture. The convex texture and the concave texture have advantages and disadvantages respectively, and the method combines the convex texture and the concave texture, thereby developing the advantages and avoiding the disadvantages.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic top view of a wear-resistant structure in an embodiment of the invention;
fig. 2 is a perspective view of a wear-resistant structure in an embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of an abrasion resistant coating in an embodiment of the invention;
FIG. 4 is a schematic cross-sectional view of a wear-resistant coating in some embodiments of the invention;
the first circular bulge, the second circular bulge, the third circular bulge, the fourth circular bulge, the fifth circular bulge, the sixth circular bulge, the concave part 20 and the second circular bulge are 11.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The following examples, which are set forth to provide a detailed description of the invention and a detailed description of the operation, will help those skilled in the art to further understand the present invention. It should be noted that the scope of the present invention is not limited to the following embodiments, and that several modifications and improvements made on the premise of the idea of the present invention belong to the scope of the present invention.
Unless otherwise defined, technical or scientific terms used in the claims and the specification of this patent shall have the ordinary meaning as understood by those of ordinary skill in the art to which this patent belongs.
As used in this specification and the appended claims, the terms "first," "second," and the like do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms "a" or "an," and the like, do not denote a limitation of quantity, but rather denote the presence of at least one. In the description of this patent, unless otherwise indicated, "a plurality" means two or more. The word "comprising" or "having", and the like, means that the element or item appearing before "comprises" or "having" covers the element or item listed after "comprising" or "having" and its equivalent, but does not exclude other elements or items.
A preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
In some embodiments, a wear resistant construction for an aluminum-based piston skirt is shown, as shown in fig. 1 and 2. In fig. 1, the wear-resistant structure protrudes from the surface of the metal substrate, and is in principle of the convex texture. The wear-resistant structure is composed of a plurality of regularly arranged bulges. The bulges are arranged in a honeycomb shape. The method specifically comprises the following steps: the surface of the skirt part of the aluminum-based piston is provided with virtual hexagons which are continuously arranged, each hexagon has the same size, and each hexagon shares a side with an adjacent hexagon and shares a vertex. Each lobe is located at an apex with which the geometric center of the lobe cross-section coincides. In other embodiments, the surface of the piston is distributed in a virtual regular hexagon, and the vertexes are provided with a first circular protrusion 11, a second circular protrusion 12, a third circular protrusion 13, a fourth circular protrusion 14, a fifth circular protrusion 15 and a sixth circular protrusion 16, which are set in such a way that the protrusions at the six vertex positions of each regular hexagon enclose a concave part 20, such as the concave part 20 in fig. 2.
Further, in some implementations, the arrangement rule of the protrusions is: the surface of the piston skirt part is repeatedly extended by the same virtual regular hexagon, each regular hexagon is shared with the adjacent regular hexagons and is shared with a vertex, and each vertex is provided with one protrusion. The round bulge edge has a round angle, the section curve of the round angle is an elliptical line, the side surface of the bulge is a curved surface, and the top surface is a spherical surface. The top surface was attached with a graphite coating containing carbon fibers, 100 microns thick.
Further, in some embodiments, the method for processing the wear-resistant structure of the aluminum-based piston skirt portion includes the following steps:
step 1, processing circular bulges on the metal surface of the skirt part of the aluminum alloy piston according to the bulge arrangement rule. The processing method is laser melting.
And 2, processing a round angle at the edge of the top surface of the bulge. This step employs a cutting and grinding process.
And 3, adding a wear-resistant coating on the top surface of the protrusion.
The preparation method of the carbon fiber reinforced graphite wear-resistant coating comprises the following steps:
and S1, adding magnetic particles on the surface of the carbon fiber to obtain the magnetic carbon fiber. This section further includes the following subdivision steps:
s1.1, carrying out ultrasonic treatment on carbon fibers in an acid solution; performing suction filtration, washing with deionized water, and repeating for multiple times until the filtrate is neutral; thus, an acid-washed carbon fiber was obtained. The acid solution is obtained by mixing nitric acid and sulfuric acid according to the mass ratio of 1:2: 2.
S1.2, fully mixing the carbon fiber after acid washing with an iron ion solution, then dropwise adding an alkaline solution into the iron ion solution until a large amount of precipitate is generated, and standing. The ferric ion solution is ferric trichloride solution and ferrous chloride solutionThe mixed solution of (1), wherein Fe 3+ With Fe 2+ Is 2:1, such a ratio may result in an iron-containing compound having magnetic properties. When the alkaline solution is dripped, the temperature of the iron ion solution is always kept at 80 ℃, which is beneficial to the full precipitation of iron ions.
S1.3, removing upper-layer liquid; carrying out suction filtration on the lower-layer precipitate, washing with deionized water, and repeating for multiple times until the filtrate is neutral; thus, magnetic carbon fibers were obtained.
And S2, adding the magnetic carbon fibers into the graphite, fully and uniformly mixing the magnetic carbon fibers and the graphite, and coating the mixture on the skirt part of the piston to form a coating precursor. In order to sufficiently disperse the magnetic carbon fibers, the carbon fibers and graphite may be put together into a dispersion medium.
And S3, applying a magnetic field outside the piston skirt. To accelerate the migration of the magnetic carbon fibers, ultrasonic oscillations are applied to the skirt portion while rotating the magnetic field about the skirt portion.
And S4, sintering and solidifying the graphite under the protection of argon, wherein the carbon fibers are solidified. The sintering temperature was 2100 ℃.
As shown in fig. 3, fig. 3 is a schematic cross-sectional view of the wear-resistant coating, with small black dots and lines indicating carbon fibers dispersed in graphite.
In some embodiments, the recess is provided in a different shape and function than conventional concave structures. In some embodiments, the recess is flush with the piston wall surface, and abrasive dust is not easy to retain; the lubricating oil of the engine is of a certain viscosity, and the lubricating oil entering the concave part from the inlet and the outlet between the bulges stays in the concave part for a short time, so that the lubricating oil is distributed on the whole wall surface of the piston during the stable operation, wherein a large amount of lubricating oil is positioned in the concave part, and a small amount of lubricating oil is positioned on the top surface and the side surface of the bulge.
Further, in some embodiments, six protrusions of the piston skirt portion at the same hexagonal apex define a recessed region that serves as a reservoir for some of the lubricating oil. Along with the movement of the piston, the lubricating oil stored in the concave area can be quickly supplied to the surface of the raised wear-resistant coating to play a lubricating role, so that the film forming property of the wear-resistant coating on the surface of the aluminum-based piston and the durability of an oil film layer attached during friction in a dry state are improved, and the friction coefficient of the skirt part of the aluminum-based piston is reduced.
In other embodiments, a method for machining a wear-resistant structure of an aluminum-based piston skirt is also provided, which comprises the following steps:
and step 1, processing the bulges on the metal surface of the skirt part of the aluminum-based piston according to the arrangement rule of the bulges. The basic shape of the protrusion can be machined rapidly and inexpensively by conventional or advanced manufacturing methods such as laser ablation, stamping, etching, etc.
And 2, processing a round angle at the edge of the top surface of the bulge. This step may be performed by cutting and grinding or other machining processes.
And 3, adding a wear-resistant coating on the top surface of the bulge or the whole surface of the piston skirt.
The substrate of the wear-resistant coating is made of graphite, the wear-resistant coating contains carbon fibers, and the carbon fibers are distributed on the surface of the wear-resistant coating and inside the surface close to the surface. As the wear resistant coating wears, the piston will be scrapped and therefore the carbon fibres located deeper therein do not exert any wear enhancing effect. Therefore, contain carbon fibers
The dimensional portion may be within one third of the vertical thickness of the wear-resistant coating, as shown in fig. 4. Fig. 4 is a schematic cross-sectional view of the wear-resistant coating, with small black dots and lines at the top showing carbon fibers dispersed in graphite.
Further, in some embodiments, the carbon fiber reinforced graphite wear-resistant coating is prepared by a method comprising the following steps:
step 1, adding magnetic particles on the surface of carbon fiber to obtain the magnetic carbon fiber. This section further includes the following subdivision steps:
step 1.1, carrying out ultrasonic treatment on carbon fibers in an acid solution; performing suction filtration, washing with deionized water, and repeating for multiple times until the filtrate is neutral; thus, an acid-washed carbon fiber was obtained. The acid solution is obtained by mixing nitric acid and sulfuric acid according to the mass ratio of 1: 1-3: 2.
Step 1.2, carbon after acid washingFully mixing the fiber and the iron ion solution, then dropwise adding an alkaline solution into the iron ion solution until a large amount of precipitate is generated, and standing. The ferric ion solution is a mixed solution of ferric trichloride solution and ferrous chloride solution, wherein Fe 3+ With Fe 2+ The mass ratio of (A) is 2:1 to 3:1, and the iron-containing compound with magnetism can be generated in the mass ratio. When the alkaline solution is dripped, the temperature of the iron ion solution is always kept at 80-90 ℃, which is beneficial to the full precipitation of iron ions.
Step 1.3, removing upper liquid; carrying out suction filtration on the lower-layer precipitate, washing with deionized water, and repeating for multiple times until the filtrate is neutral; thus, magnetic carbon fibers were obtained.
And 2, adding the magnetic carbon fibers into the graphite, fully and uniformly mixing the magnetic carbon fibers and the graphite, and coating the mixture on the skirt part of the piston to form a coating precursor. In order to sufficiently disperse the magnetic carbon fibers, the carbon fibers and graphite may be put together into a dispersion medium.
And 3, applying a magnetic field on the outer side of the piston skirt part to enable the magnetic carbon fibers to migrate and enrich towards the surface of the coating precursor and the inner part close to the surface. To accelerate the migration of the magnetic carbon fibers, ultrasonic oscillations may be applied to the piston skirt while rotating the magnetic field about the piston skirt.
And 4, sintering and solidifying the graphite under the protection of inert gas (such as argon), wherein the carbon fiber is solidified. The sintering temperature is above 2000 ℃.
Further, in some embodiments, six protrusions of the piston skirt portion at the same hexagonal apex define a recessed region that serves as a reservoir for some of the lubricating oil. Along with the movement of the piston, the lubricating oil stored in the depressed area can be quickly supplied to the surface of the raised wear-resistant coating to play a lubricating role, so that the film forming property of the wear-resistant coating on the surface of the aluminum-based piston and the durability of an oil film layer attached during friction in a dry state are improved, and the friction coefficient of the skirt part of the aluminum-based piston is reduced.
The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims (7)

1. A wear-resistant structure for an aluminum-based piston skirt is characterized by comprising a plurality of protrusions regularly distributed on the surface of the piston skirt; the arrangement rule of the bulges is as follows: the surface of the piston skirt part is repeatedly extended by the same virtual hexagon, each hexagon shares a side with the adjacent hexagon and a vertex, and each vertex is provided with one protrusion; the aluminum-based piston comprises an aluminum alloy piston or an aluminum-based composite material piston; the cross section of the protrusion is circular, and the radius of the circle is 1/3-1/2 of the side length of a hexagon;
the processing method of the wear-resistant structure comprises the following steps:
a1, processing bulges on the metal surface of the piston skirt part, wherein the arrangement rule of the bulges is as follows: the surface of the piston skirt part is repeatedly extended by the same virtual hexagon, each hexagon shares a side with the adjacent hexagon and a vertex, and each vertex is provided with one protrusion;
a2, processing a round angle on the edge of the top surface of the bulge;
a3, adding a wear-resistant coating on the top surface of the bulge or the whole surface of the piston skirt;
the preparation method of the coating comprises the following steps:
s1, adding magnetic particles on the surface of the carbon fiber to obtain magnetic carbon fiber;
s2, adding the magnetic carbon fiber into graphite, fully and uniformly mixing, and coating on the skirt part of the piston to form a coating precursor; in order to sufficiently disperse the magnetic carbon fibers, the carbon fibers and graphite may be put together into a dispersion medium;
s3, applying a magnetic field on the outer side of the piston skirt to enable the magnetic carbon fibers to migrate to the interior of the coating precursor;
s4, sintering and solidifying the graphite under the protection of inert gas, wherein the carbon fiber is solidified;
step S1 includes the following subdivision steps:
s1.1, carrying out ultrasonic treatment on carbon fibers in an acid solution; performing suction filtration, washing with deionized water, repeating for many times until the filtrate is neutral, and obtaining the carbon fiber after acid washing;
s1.2, fully mixing the carbon fiber after acid washing with an iron ion solution, then dropwise adding an alkaline solution into the iron ion solution until a large amount of precipitate is generated, and standing;
s1.3, removing upper-layer liquid; carrying out suction filtration on the lower-layer precipitate, washing with deionized water, and repeating for multiple times until the filtrate is neutral; thus, magnetic carbon fibers were obtained.
2. The wear structure for an aluminum-based piston skirt as in claim 1, wherein said hexagon is a regular hexagon.
3. A wear structure for an aluminum-based piston skirt as claimed in claim 1, wherein top surface edges of said protrusions are rounded; the section curve of the fillet is an elliptical line.
4. A wear structure for an aluminum-based piston skirt as claimed in claim 1, wherein the side surface of said projection is straight or curved.
5. A wear structure for an aluminum-based piston skirt as claimed in claim 1, wherein the top surface of the boss or the entire surface of the piston skirt is coated with a wear resistant coating.
6. The wear structure for the aluminum-based piston skirt according to claim 5, wherein said wear-resistant coating contains carbon fibers, and said carbon fibers are uniformly distributed in said wear-resistant coating.
7. An aluminum-based piston, characterized in that the surface of the skirt portion of the piston is provided with a wear-resistant structure as claimed in any one of claims 1 to 6.
CN202110834237.XA 2021-07-21 2021-07-21 Wear-resistant structure for aluminum-based piston skirt and machining method thereof Active CN113417754B (en)

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US4987865A (en) * 1989-10-11 1991-01-29 Wickes Manufacturing Company Reduced friction piston
CN2365410Y (en) * 1999-03-26 2000-02-23 山东活塞厂 Low-friction type piston
CN2900825Y (en) * 2006-04-19 2007-05-16 重庆长安汽车股份有限公司 Piston skirt external cylindrical surface structure
CN101178124A (en) * 2007-12-03 2008-05-14 周林 High-lubricating low-friction piston
CN104024615B (en) * 2011-12-28 2016-08-17 本田技研工业株式会社 Piston for explosive motor
CN103244306A (en) * 2013-04-16 2013-08-14 南平华田机械工业有限公司 Engine aluminum piston with coating on surface of skirt
JP6587978B2 (en) * 2016-06-01 2019-10-09 株式会社クボタ Engine pistons

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