JPH09256903A - Piston for internal combustion engine and manufacturer thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve work efficiency in piston manufacturing, reduce piston cost, ensure wear and agglutination resistance and adhesion resistance and improve the junction strength of the junction boundary surface of a piston body and an aluminum alloy member. SOLUTION: This invention relates to a piston for an internal combustion engine, wherein three grooves for piston rings are formed in the ring land section 3 of a piston body 1 made of aluminum alloy. A ring-like recessed section 22 is formed at a position corresponding to the groove 4 of a top ring for the groove of the piston rings, and an aluminum alloy member 11 containing the particles of silicon carbide SiC is cast in the recessed section 22. The junction boundary surface 20 of at least the upper and lower face of the aluminum alloy member 11 and the inner face of the groove 4 for the top ring is irradiated by an electronic beam of high energy density is fused and jointed again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for an internal combustion engine such as an automobile and a method for manufacturing the piston.

[0002]

2. Description of the Related Art As is well known, in recent years, pistons of internal combustion engines for automobiles have been formed of aluminum alloy instead of cast iron in order to reduce weight in response to demands for higher output and higher performance. Further, a plurality of piston ring grooves in which a piston ring is mounted are formed on the outer peripheral surface facing the inner wall surface of the cylinder bore. Furthermore, of these piston ring grooves, the top ring groove closest to the combustion chamber is
In particular, the piston ring (top ring) is exposed to high temperatures and is directly subjected to combustion pressure, so that the piston ring (top ring) is severely worn. Therefore, aluminum adhesion easily occurs between the top ring groove and the top ring.

Therefore, various techniques for preventing such aluminum adhesion have been developed. For example, (1) a method in which an inorganic fiber aggregate is compounded on the surface portion of the top ring groove to strengthen it (JP-A-59-59). (201953), and (2) In-
Application of hybrid MMC (metal-based composite material) to the piston by the Situ process (Automotive Technology 198)
9-5. No. 891056), and (3) a porous nickel body is compounded on the surface portion of the top ring groove to strengthen it (Japanese Patent Publication No. 3-30708). Also, (4)
An alloy layer is formed by strengthening the surface of the top ring groove with an alumite treatment layer (JP-A-1-190951), or (5) melting and diffusing copper or the like with an electron beam on the surface of the top ring groove. Things (Mitsubishi Motors 19
88, NO1 "Technical Review", Japanese Patent Laid-Open No. 2-12
No. 5952), and many other improved techniques have been proposed, such as (6) a ring support member in which a niresist cast iron is alfin-finished in a top ring groove portion and cast into an aluminum alloy.

[0004]

However, each of the conventional examples has the following disadvantages. That is, (1),
In the conventional examples of (2) and (3), the high pressure solidification method must be used as the forming method in view of the material such as the inorganic fiber material. Therefore, not only is the manufacturing cost increased, but the shape of the piston is restricted.

Further, in the conventional example of (4), the alumite treatment layer improves the adhesion resistance to the piston ring, but the abrasion resistance becomes insufficient. Further, in the conventional example of (5), there is a possibility that the adhesion resistance is insufficient.

The prior art (6) is the oldest technique. Although it is possible to secure abrasion resistance and adhesion resistance, it is made of cast iron, so that the weight must be increased. . Further, as another conventional example, Japanese Patent Laid-Open No. 2-1011
No. 41, the aluminum alloy contains Si, Cu, Mg, Fe, and Mn in predetermined weight percentages, respectively.
Is also provided to form a high-strength aluminum alloy by dispersing one kind of particles such as Al ₂ O _{3 in} the matrix of this aluminum alloy powder, but this material is When remelted by a heat source,
During the joining of the remelted portion, blowholes may be generated in the remelted portion. This is because unavoidable air exists between the powder particles and may remain until final processing.

[0007]

The present invention has been devised in view of the actual situation in each of the above-mentioned conventional examples, and the invention of claim 1 is such that a plurality of pistons are provided on the outer periphery of a piston body made of an aluminum alloy. In a piston of an internal combustion engine in which a ring groove is formed, an annular recess is formed at a position corresponding to at least the top ring groove of the piston ring groove, and a ring groove containing silicon carbide particles is formed in the annular recess. An aluminum alloy member for use in casting, and the joining interface between the aluminum alloy member and the recess is remelted and joined by a heat source having a high energy density, and a ring groove is formed on the outer periphery of the aluminum alloy member. It is characterized by that.

According to a second aspect of the present invention, there is provided a method of manufacturing a piston for an internal combustion engine, in which an aluminum alloy member for forming a piston ring groove is cast on the outer circumference of a piston body made of an aluminum alloy. An annular recess is formed at a position corresponding to at least the top ring groove of the piston ring groove, and subsequently, an aluminum alloy member containing silicon carbide particles is cast and solidified in the recess, and then the aluminum It is characterized in that the joint boundary surface between the alloy member and the concave portion is remelted by a heat source having a high energy density and cooled and jointed.

According to a third aspect of the present invention, in a piston of an internal combustion engine in which a plurality of piston ring grooves are formed on the outer circumference of a piston body made of an aluminum alloy, the piston ring groove is provided at a position corresponding to at least the top ring groove. An annular recess is formed, and an aluminum alloy member for forming a ring groove, which contains silicon carbide particles and contains a higher concentration of an alloy element than the base material of the piston body, is formed in the recess by casting, and The joint interface between the aluminum alloy member and the recess is remelted by a heat source having a high energy density, and the aluminum alloy in the remelted portion is 10.0 wt% ≤ Cu ≤ 23.0 wt% and is unavoidable. Aluminum alloy matrix containing impurities, Al ₂
O ₃ particles, SiC particles, Si ₃ N ₄ particles, ZrO ₂ particles, S
At least one kind of hard particles selected from TiO ₂ particles, TiO ₂ particles, WC particles and metal Si particles is dispersed in the aluminum alloy matrix in an amount of 5% by volume or more and 25% by volume or less.

[0010]

According to the present invention having the above-mentioned structure, the aluminum alloy member for forming the piston ring groove can be formed by casting or the like from the point of view of the material, and the aluminum alloy member is simply cast when the piston body is formed. Since it is formed by the manufacturing method, the manufacturing cost can be reduced. Further, the SiC particles in the aluminum alloy member improve wear resistance to the piston ring and also improve adhesion resistance.

Moreover, the joint boundary surface between the concave portion and the aluminum alloy member is irradiated with, for example, an electron beam to be remelted,
Since cooling and bonding are performed thereafter, a homogeneous alloy layer is formed by remelting and the bonding strength at the interface between the two can be significantly increased.

According to the third aspect of the present invention, the alloy component of the remelted portion after melting is optimally adjusted to prevent a decrease in alloy concentration and to improve wear resistance and adhesion resistance. be able to.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIGS. 1 and 2 are cross-sectional views of a piston for an internal combustion engine according to the present invention.
Are made of aluminum alloy (JIS AC8A-T6) and are formed in a substantially cylindrical shape, and three piston ring grooves formed on the outer peripheral surface of the crown portion 2 facing the combustion chamber and the ring land portion 3 provided under the crown portion 2. 4, 5, 6 and piston rings 7, which are fitted in the respective tops, second and oil ring grooves 4 to 6,
8 and 9 and a skirt portion 10 below each of the ring grooves 4 to 6.

The top ring groove 4 is formed on the top surface 2 of the crown portion 2.
A width of 4 mm and a depth of 8 mm are formed around a position 9 mm away from a, and this surface portion is formed by an aluminum alloy member 11 formed by a forming method described later.

The aluminum alloy member 11 is made of an aluminum alloy containing particles of silicon carbide (SiC), and is integrally formed in the annular recess 22 of the piston body 1 by casting.

Hereinafter, a specific method for manufacturing the piston will be described. That is, first, the aluminum alloy material (JIS AC8A-T6) of the piston body 1 is melted and held at 993K. On the other hand, regarding the aluminum alloy member 11, the maximum diameter is several μm to several tens μm of SiC.
An aluminum alloy cast ingot containing 10 to 20% of particles is melted in an inert atmosphere such as argon gas,
After holding at 993K, mechanical stirring is performed to uniformly disperse the SiC particles in the aluminum alloy material.

After that, the piston body 1 and the aluminum alloy member 11 are cast by the mold shown in FIGS. In the figure, 31 is an upper die, 32 is a main die, 33 is a lower die, 34
Is a core, 35 is a concave part forming die having a convex part 35a on the inner peripheral portion, 36 is a substantially annular alloy member forming mold which is replaced with the concave part forming die 35 in the molding step, and 37 and 38 are runners. Three
9 is a feeder.

Then, as shown in FIGS. 3A and 3B, a molten aluminum alloy material (AC8A) is first poured into the cavity 40 from the spout 37a of the runner 37. This molten metal is filled into the cavity 40 and then solidified to cast the piston body 1. At that time, as shown in FIG. 3B, an annular recess 22 is formed by the recess forming die 35 at a position corresponding to the top ring groove of the piston body 1.

Next, as shown in FIG. 3C, the recess forming mold 35 is removed from the main mold 32 and replaced with an alloy member forming mold 36. That is, the alloy member forming die 36 is attached. Therefore, an annular cavity 23 is formed between the inner peripheral surface of the alloy member forming die 36 and the inner surface of the recess 22. In addition, the recess forming mold 35 includes the runner 38 and the cavity 4.
However, the runner 38 and the cavity 40 are communicated with each other by a communication hole 36a formed in a predetermined portion of the alloy member forming die 36.

Subsequently, as shown in FIG. 3D, a molten aluminum alloy material containing silicon carbide particles is poured into the cavity 23 from the gate 38a of the runner 38 and solidified.

After that, the mold is released to take out the casting,
When the remaining part of the feeder 39 and the remaining parts of the runners 37, 38 are cut, the rough material of the piston in which the aluminum alloy member 11 containing the particles of silicon carbide is formed in the recess 22 of the piston body 1 is completed.

Further, when pouring the aluminum alloy member 11 containing silicon carbide, the heating temperature of the molten metal is raised,
Further, when the piston body 1 is sufficiently preheated, a phenomenon in which the joining boundary surface 20 between the two is sufficiently welded is recognized, but the temperature condition range is extremely narrow, and it is difficult to perform uniform joining. Therefore, in the present embodiment, the joining boundary surface 20 between the aluminum alloy member 11 and the piston body 1 is remelted and joined by a heat source having a high energy density such as an electron beam or a TiG laser.

The steps of remelting and joining the aluminum alloy member 11 with the piston body 1 will be described below with reference to FIGS.
It will be described based on. First, as shown in FIG. 4, the outer periphery of the ring land portion 3 of the piston body 1 in which the outer peripheral surface 11a of the aluminum alloy member 11 is exposed is cut to make the surface smooth. After that, as shown in FIGS. 5A and 5B, the boundary surface 20 between the upper and lower surfaces of the aluminum alloy member 11 and the ring land portion 3 is re-melted by a high heat source by irradiating a high energy beam of an electron beam, for example. That is,
The respective aluminum alloys of the piston body 1 and the aluminum alloy member 11 are remelted and then rapidly cooled to be solidified. Therefore, a uniform alloy layer is formed on the boundary surface 20 by the remelting portion 21 and high joint strength is obtained. After remelting and strong joining, the ring groove 4 is formed on the outer peripheral portion of the aluminum alloy member 11 as shown in FIG. 5C.
Is cut into a ring.

FIGS. 6A and 6B show a second embodiment in which the entire joint boundary surface 20 between the aluminum alloy member 11 and the ring land portion 3 is remelted and joined. Forming the top ring groove 4 on the outer peripheral portion of the aluminum alloy member 11 as shown in the figure is the same as in the previous embodiment, and by remelting, the aluminum alloy member 11 and the piston body 1 are separated from each other in the same manner as in the above embodiment. A strong bond can be obtained. Particularly, in this embodiment, the SiC particles in the remelting portion 21 are very uniformly dispersed. This is due to the stirring effect and the quenching effect of the high energy beam of the electron beam.

FIG. 7A is a drawing showing a photograph of a sectional structure before remelting with the high energy beam, and FIG. 7B is a drawing showing a photograph of a sectional structure after remelting. As is apparent, the Si in the aluminum alloy near the upper and lower surfaces of the aluminum alloy member 11 before remelting
C particles (black dots) are locally gathered,
After remelting, as apparent from FIG. 7B, SiC particles are uniformly dispersed throughout the aluminum alloy member 11
And each aluminum alloy of the piston body 1 becomes a homogeneous alloy phase and is strongly metallurgically bonded.

The aluminum alloy member 11 and the piston body 1 are such that the aluminum alloys themselves are remelted and metal-bonded to each other.
The volume percentage of the SiC particles of No. 1 is slightly reduced. Therefore, as in the first embodiment, the top ring groove 4 has the re-melting portion 2
If it does not exceed 1, the problem does not occur, but in the case of applying to the remelting portion or in the case of the second embodiment, the volume% of SiC particles is
In order not to significantly reduce the amount of aluminum alloy, it is necessary to reduce the melting amount of the aluminum alloy on the piston body 1 side. Therefore, it is desirable that the melting amount of the aluminum alloy on the piston body 1 side be at least about 1 mm from the outer peripheral surface of the aluminum alloy member 11.

8 to 9 show a third embodiment of the present invention,
It shows a manufacturing method in which the aluminum alloy member 11 is exposed to the crown portion 2 of the piston body 1 to minimize the top land height H.

That is, the aluminum alloy member 11 is previously
After being provided in the concave portion 22 formed in the crown portion 2 of the piston body 1 as shown in FIG. 8, the electron beam is emitted from above the crown portion 2 and from the side of the ling ground portion 3 as shown in FIG. 9B. The high energy beam is applied to the aluminum alloy member 11 and the recess 22.
The joining boundary surface 20 with is irradiated with and re-melted, and then the re-melted portion 21 is cooled and solidified to join. Subsequently, as shown in FIG. 9C, the top ring groove 4 is formed on the outer peripheral surface of the aluminum alloy member 11.

Therefore, according to this embodiment, the top land height H can be made as small as possible, and since the corner portion C of the crown portion 2 is the aluminum alloy member 11, the strength is high. Is significantly improved, and it becomes possible to sufficiently cope with the high output of the engine.

Further, in this case, the boundary surface 20 between the aluminum alloy member 11 and the piston body 1 is exposed on the upper surface of the crown portion 2 which is exposed to high heat. This portion is a remelted portion having a large bonding strength. Therefore, the peeling phenomenon between the two is surely prevented. That is, when the Ni-resist cast iron is joined to the aluminum alloy member and the piston main body by the Alfin treatment as in the conventional example (6),
Although there is a risk that the joint boundary surface 20 will not be able to withstand the thermal stress generated in the crown portion and that peeling may occur at the joint boundary surface 20, such peeling phenomenon can be reliably avoided in the case of the present embodiment.

Below, the results of experiments on changes in the properties of the joint boundary surface 20 of the aluminum alloy member 11 formed by the above-described process with respect to strength, wear resistance, adhesion resistance and machinability will be described.

First, Table 1 shows the components of the aluminum alloy of the matrix. In this experiment, a sample manufactured by a casting method was used. The amount of SiC particles added was 0,
Seven types of materials were evaluated at 5, 10, 15, 20, 25, and 30% by volume.

[0034]

[Table 1]

Then, the evaluation method of wear resistance was carried out by using the apparatus shown in FIG. That is, the piston ring 7 is fixed on the rotary table 15 which is rotated by a motor (not shown), and the test piece 17 fixed to the lower end of the heater 16 is pressed against the piston ring 7 to wear it. The test piece 17 is an aluminum alloy member cut out from the ring groove of the piston body 1. The test conditions such as temperature and lubrication condition in this method are assumed to be correlated with the actual piston of the engine. The evaluation was performed by the wear depth after the test.

The adhesion resistance is evaluated by using the apparatus shown in FIG. 11, the piston ring 7 is pressed against the lower surface of the top ring groove 4 of the piston body 1, and the arrows are passed through the actuators 18 and 19. It was based on the accelerated test method of sliding only in one direction. The evaluation was performed based on the ratio of the area of the ring groove 4 where the cohesive wear occurred to the sliding area of the piston ring 7.

The machinability was evaluated by machining a cylindrical rough material having a diameter of 70 mm under the following processing conditions and the wear amount of the tool was 0.3 mm.
It was evaluated by the number of processings until it became. Cutting speed: 200m / mi
n, Depth of cut: 0.3 mm, Feed: 0.03 mm (per rotation), Tool: Vapor phase synthetic diamond tool (manufactured by Asahi Diamond Co., Ltd.) Table 2 shows the evaluation results.

Here, the abrasion resistance indicates a ratio with the abrasion amount of SiC particles not added (O) as 100. The smaller the value, the less wear.

The anti-adhesion property is a ratio of the area where the SiC particles are adhered without addition as 100. The smaller the value, the less adhesion.

As for machinability, the tool life was set to 100 when a rough material without addition of SiC particles was machined using CPX as a tool. However, the coarse material to which the SiC particles are added is processed by a vapor phase synthetic diamond tool.

[0041]

[Table 2]

As is clear from Table 2, even if the amount of SiC particles added is 5% by weight, the wear resistance is remarkably improved as compared with the case where no addition is made, and at 10% by volume, the effect becomes almost constant.

On the other hand, the adhesion resistance tends to be the same as that of Si.
It can be seen that even when the addition amount of the C particles is 5% by volume, it is significantly improved as compared with the case where no C particles are added. However, no adhesion occurs at 10% by volume or more.

Further, the machinability of the SiC particles becomes worse even if the added amount of the SiC particles is 5% by volume, as compared with the case where the SiC particles are not added. Further, as the amount of addition increases, the processability deteriorates.
At volume%, the cutting edge of the tool is chipped and cannot be machined.

From the above experiment, it can be seen that the optimum addition amount of SiC particles is 5% by volume to 25% by volume, preferably 10% by volume to 20% by volume.

Further, a test was carried out by incorporating the above-described piston formed by casting the aluminum alloy member 11 in the aluminum alloy piston body 1 into an internal combustion engine. Here, Si of the aluminum alloy member 11
The amount of C particles added was set to 10% by volume. For comparison, a piston test in which the aluminum alloy member 11 as described above is not formed on the piston body 1 was also tested.

The operating conditions are four cylinders and a displacement of 1,600.
Oil temperature 150 degrees, cooling water temperature 1 using a cc gasoline engine
Continuous operation was performed at 20 degrees for 100 hours.

As a result, the piston not provided with the aluminum alloy member 11 was abraded by 50 μm, and adhesion was observed in 85% of the lower surface of the top ring groove.
No wear or adhesion was observed on the piston that was cast around the aluminum alloy member 11.

Further, the shear strength of the joint between the aluminum alloy member 11 containing 10% by volume of SiC particles and the piston main body 1 in the embodiment of the present invention is determined by comparing the conventional joint between the aluminum alloy member obtained by alfining Niresist cast iron and the piston main body. Experiments were performed comparing with the shear strength of.
As a result, it was revealed that the shear strength according to the present invention is four times or more that of the conventional example, as shown in FIG.

In the embodiment of the invention described in claim 3, the components contained in the aluminum alloy base material of the aluminum alloy member 11 cast in the piston body 1 in each of the above-mentioned embodiments are changed, and the components to be described later are changed. The alloy composition of the fusion zone is optimally adjusted.

That is, the aluminum alloy member 11 is made of Si.
An aluminum alloy ingot containing 20% by volume of C particles is melted and the molten metal temperature is maintained at about 740 ° C. The aluminum alloy ingot is a product name DURALCAN
Based on the main component (see F3K / 20S catalog), Cu, Ni, Mn, and Si are added in the form of mother alloy or pure metal as shown in the following table so as to be the target components. Here, Cu was added in the form of a copper wire, Ni was a powder or wire, Mn was Al-60Mn, and Si was a master alloy of Al-40Si.

[0052]

[Table 3]

When the addition amount of the hard particles is specified as described above, the dispersion state of the hard particles in the aluminum alloy matrix is optimum for improving the wear resistance of the aluminum alloy. Further, hard particles fix crystal dislocations in the aluminum alloy matrix to improve creep properties and stress corrosion cracking resistance properties, lower thermal expansion coefficient, Young's modulus and fatigue strength, wear resistance, adhesion resistance, etc. Have various effects.

However, when the content of the hard particles in the aluminum alloy matrix is less than 0.5% by weight, the wear resistance is not improved, the Young's modulus is improved, and the coefficient of thermal expansion is also decreased. , 15.0% by volume, the wear of the mating material increases.

The reasons for containing the other components and the reasons for limiting the contents are as follows.

(A) Regarding Cu Cu has the effect of forming an intermetallic compound and strengthening the aluminum alloy matrix to improve wear resistance and adhesion resistance. However, if the content is less than 10% by weight, the above effect cannot be obtained. On the other hand, if the content is more than 23% by weight, the material becomes very hard, becomes brittle, and deteriorates in wear resistance. Then, the amount of Cu in the fusion zone was changed and a wear test was conducted,
The result is 3. In addition, the evaluation method of wear resistance is
It carried out using the apparatus shown in FIG. That is, a piston ring is fixed on a turntable that is rotated by a motor (not shown), and a test piece fixed to the lower end of the heater is pressed against the piston ring to wear it. This test piece is an aluminum alloy member cut out from the ring groove of the piston body.
Test conditions such as temperature and lubrication state in this method were assumed to be correlated with the actual engine piston. The evaluation was performed based on the wear depth after the test.

The components of the aluminum alloy member are adjusted in advance to have such a composition.

After adjusting to the target component, Si in the molten metal is adjusted.
The molten metal is stirred to uniformly disperse the C particles. Then, the aluminum alloy member 11 is cast by the above-mentioned method.

The aluminum alloy member 11 after casting
Since the alloy base material has a high hardness, it becomes difficult to perform cutting, and therefore it is desirable to cast the alloy base material into a near net (near net) shape.

After casting the aluminum alloy member 11, the outer peripheral surface of the aluminum alloy member 11 may be smoothed by cutting the outer periphery of the ring land portion 3. Then, the boundary surface 20 between the aluminum alloy member 11 and the piston body 11 is remelted and joined with a heat source having a high energy density of the electron beam.

Here, when the aluminum alloy base material of the piston body 1 is, for example, AC8A, the alloy concentration of the remelted portion 21 becomes lower than the above target component, and Cu is about 20.0 wt% and SiC is about. It will be 10% by volume. These are typical values of the alloy components to be finally obtained.

That is, the aluminum alloy in the remelting portion 21 is 10.0% by weight ≦ Cu ≦ 23.0% by weight, and the Sic particles are 5% by volume or more and 25% by volume or less.

By setting the alloy concentration in the remelting portion 21 in this way, it is possible to prevent the formation of blowholes in the remelting portion 21 and prevent the alloy concentration from decreasing.

That is, if the alloy concentration of the remelting portion 21 is set as in the present embodiment, it is possible to prevent air from remaining between the powder particles and prevent the alloy concentration from decreasing, so that the aluminum alloy powder is Like the materials used, it is possible to improve wear resistance and adhesion resistance.

The present invention is not limited to the construction of the above-mentioned embodiment. For example, the width of the aluminum alloy member 11 is set to be large, and the top ring groove and the other two piston ring grooves are formed in the outer peripheral portion. It is also possible to do so.

[0066]

As is apparent from the above description, claim 1
According to the invention described in 1 and 2, since the aluminum alloy member for forming the ring groove containing the SiC particles is formed by casting in the concave portion of the piston body made of aluminum alloy, the conventional high pressure solidification method is used. Without gravity, it can be formed by gravity casting.

Moreover, as in the case of the conventional Niresist cast iron turning method, the separately manufactured cast-in-stock material is not provided around the piston body, but an aluminum alloy member is used when the piston body is cast. Since it is formed directly on the main body, the manufacturing work efficiency can be improved and the cost can be reduced.

Further, since the boundary surface between the piston body and the aluminum alloy member is remelted by the high energy heat source and cooled and bonded, the bonding strength at the boundary surface portion becomes extremely high. In addition, the unique internal structure of the aluminum alloy member can reduce the weight, and since the SiC particles are uniformly dispersed, the wear resistance and the adhesion resistance can be improved.

Furthermore, according to the third aspect of the present invention, a decrease in alloy concentration is prevented, and wear resistance, adhesion resistance and the like are further improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a piston showing an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a piston of this embodiment.

3A to 3D are explanatory views showing a forming process of the piston of the present embodiment.

FIG. 4 is a vertical cross-sectional view showing a state in which an aluminum alloy member is formed in a concave portion of a piston crown portion.

5A is an enlarged view of an essential part of FIG. 4, B is an enlarged view of an essential part showing a remelted portion of a boundary surface between a piston body and an aluminum alloy member, and C is a state in which a ring groove is cut on the aluminum alloy member. FIG.

FIG. 6A is an enlarged cross-sectional view showing a second embodiment of the present invention showing an aluminum alloy member for forming a ring groove and a remelted portion of a piston body, and B is a state in which a ring groove is cut on the aluminum alloy member. FIG.

FIG. 7A is a structural diagram showing a micrograph of an aluminum alloy member before remelting, and B is a structural diagram showing a micrograph of a boundary surface portion after remelting.

FIG. 8 is a vertical cross-sectional view showing a third embodiment of the present invention and showing a state in which an aluminum alloy member is formed on the top land of the crown portion.

FIG. 9A is an enlarged view of a main part before remelting of the present embodiment,
B is an enlarged view of an essential part showing a state in which the entire aluminum alloy member and the boundary surface of the piston body are remelted, and C is an enlarged view of an essential part showing a state in which a ring groove is cut on the outer periphery of the aluminum alloy member after remelting and joining. Fig.

FIG. 10 is an explanatory diagram showing a wear resistance test device.

FIG. 11 is an explanatory view showing an adhesion resistance test device.

FIG. 12 is a bar graph showing the shear strengths of the present invention and a conventional example in comparison.

FIG. 13 is a graph showing the results of a wear test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piston main body 2 ... Crown part 3 ... Ring land part 4 ... Top ring groove 7 ... Top ring 11 ... Aluminum alloy member 20 ... Boundary surface 21 ... Remelting part.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location B23K 15/00 505 B23K 15/00 505 26/00 310 26/00 310N F16J 1/01 F16J 1/01 9 / 00 9/00 A

Claims (3)

[Claims] 1. A piston of an internal combustion engine having a piston body made of an aluminum alloy and having a plurality of piston ring grooves formed on an outer periphery thereof, wherein an annular recess is provided at a position corresponding to at least the top ring groove of the piston ring groove of the piston body. Together with forming a ring groove forming aluminum alloy member containing particles of silicon carbide by casting in the annular recess, and the bonding interface between the aluminum alloy member and the recess, high energy density of A piston for an internal combustion engine, characterized in that the aluminum alloy member is remelted and joined by a heat source and a ring groove is formed on the outer periphery of the aluminum alloy member. 2. A method of manufacturing a piston for an internal combustion engine, wherein an aluminum alloy member for forming a piston ring groove is cast on an outer circumference of a piston body made of an aluminum alloy, wherein the piston ring groove is formed when the piston body is molded. An annular recess is formed at a position corresponding to at least the top ring groove, and subsequently, in the recess, after casting and solidifying an aluminum alloy member containing particles of silicon carbide,
A joint boundary surface between the aluminum alloy member and the recess,
A method for manufacturing a piston for an internal combustion engine, characterized in that the piston is remelted by a heat source having a high energy density and then cooled and bonded. 3. A piston of an internal combustion engine having a plurality of piston ring grooves formed on the outer circumference of a piston body made of an aluminum alloy, wherein an annular recess is formed at a position corresponding to at least the top ring groove of the piston ring groove. With the inside of the recess,
An aluminum alloy member for forming a ring groove, which contains particles of silicon carbide and contains a higher concentration of alloying element than the base material of the piston body, is formed by casting, and a joining boundary surface between the aluminum alloy member and the recess is formed. The aluminum alloy in the remelted portion is further melted by a heat source having a high energy density, and the aluminum alloy matrix containing 10.0 wt% ≤ Cu ≤ 23.0 wt% and inevitable impurities is Al ₂ O ₃ Particles, SiC particles, Si ₃ N ₄ particles, ZrO
_At least one kind of hard particles selected from ₂ particles, SiO ₂ particles, TiO ₂ particles, WC particles and metallic Si particles,
A piston for an internal combustion engine, characterized in that it is dispersed in an amount of 5% by volume or more and 25% by volume or less with respect to the aluminum alloy matrix.