JP2001334358A - Method for manufacturing engine block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an engine block which is capable of integrating a liner of an aluminum base material to the engine block made of an aluminum alloy with tight adhesion by a simple and inexpensive method. SOLUTION: The liner is formed of the aluminum base material and a film consisting of metal having a melting point lower than the melting point of the aluminum base material forming the liner is formed on the outer peripheral surface of the liner. This liner is installed at the prescribed point of a die cavity and is cast-in cast by die casting using the aluminum alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an engine block for an engine (internal combustion engine) for an automobile, a motorcycle, an industrial machine, or the like, and more particularly, to a method for manufacturing an engine block formed by die casting using an aluminum alloy. More specifically, the present invention relates to a method for manufacturing an aluminum alloy engine block in which a liner formed of an aluminum base material is cast by die casting using an aluminum alloy.

[0002]

2. Description of the Related Art Conventional engine blocks cast using an aluminum alloy are inferior in abrasion resistance and heat resistance due to the properties of the material. Therefore, cast iron material is particularly used for the piston sliding portion (bore portion). It was necessary to ensure the durability by installing a separately formed liner. However, recently, an aluminum alloy engine block in which the wear resistance and heat resistance of the piston sliding portion (bore portion) are enhanced as much as cast iron without using a liner, or By casting a liner made of an aluminum-based base material whose heat resistance is enhanced as much as cast iron by die-casting using an aluminum alloy, it is lightweight, has high heat dissipation, and wear resistance in the sliding part of the piston And engine blocks made of aluminum alloy with excellent heat resistance.

However, as a practical matter, when manufacturing an aluminum alloy engine block which is excellent in wear resistance and heat resistance in a piston sliding portion without using a liner at all, this type of casting aluminum alloy is There is a problem that productivity is inferior because the castability is poorer than the original and the quality control is difficult, and the liner made of aluminum base material such as aluminum alloy and aluminum base composite material is cast when the engine block is cast. In the case of casting, an oxide film (A
l ₂ O ₃ ) and the like, it is very difficult to integrate the liner into the cylinder jacket portion made of an aluminum alloy with good adhesiveness. Therefore, an engine block made of an aluminum alloy having high expected heat dissipation is required. There was a problem that could not be obtained.

Therefore, a technique has been proposed in which particles are shot on the outer peripheral surface of a liner made of an aluminum-based base material to form a special rough surface, thereby improving the adhesion to a cylinder jacket portion made of an aluminum alloy. (See Japanese Patent Application Laid-Open No. 10-94867). However, this proposal requires special management in terms of casting technology, and has problems such as an increase in cost.

[0005]

Under such circumstances, the inventors of the present invention have proposed a method for integrating a liner made of an aluminum base material into a cylinder jacket portion of an engine block made of an aluminum alloy with good adhesion. As a result of intensive research, a metal coating (eg, zinc alloy coating) having a lower melting point than the aluminum-based base material is interposed between the base material and the liner made of the aluminum alloy, so that the liner made of the aluminum-based base material is connected to the aluminum alloy. To be able to integrate with the cylinder jacket part of the engine block made of aluminum with good adhesion, and to form a metal film with a lower melting point than the aluminum base material on the outer peripheral surface of the liner made of aluminum base material. , Liner based on aluminum By rubbing the peripheral surface of the liner in a state of immersed more in the low melting point molten metal, at the same time the oxide film when the oxide film or the like is removed made of Al ₂ O ₃ present on the outer peripheral surface of the liner A film made of the low melting point metal is formed on the removed liner outer peripheral surface, and as a result, the air does not intervene between the liner surface and the film made of the low melting point metal from which the oxide film or the like has been removed, It has been found that the film made of the low melting point metal is firmly and uniformly attached to the outer peripheral surface of the liner.

The present invention has been made on the basis of such knowledge. However, if the thickness of the low-melting-point metal film formed on the outer peripheral surface of the liner is too large, the liner may be cast at the time of die casting. The present inventors have also found out that the low-melting metal film is dissolved in the aluminum alloy melt and mixed into the product when the product is melted, thereby causing the product to lose its strength.

An object of the present invention is to easily and surely form a film made of a metal having a lower melting point than the liner on the outer peripheral surface of a liner made of an aluminum-based base material. An object of the present invention is to provide a method of manufacturing an aluminum alloy engine block that can be integrated with a jacket with good adhesion.

[0008]

According to the present invention, there is provided a method for manufacturing an engine block, comprising: forming a liner with an aluminum base material; and forming an outer peripheral surface of the liner, that is, an aluminum alloy forming the engine block. On the surface in direct contact with the base material, a film made of a metal having a lower melting point than the aluminum base material forming the liner is formed, and then the liner is installed at a predetermined position in the mold cavity. The present invention is characterized in that the casting is performed by casting by die casting using an aluminum alloy (claim 1). At this time, as a method of forming a film made of a metal having a lower melting point than the aluminum base material forming the liner (hereinafter, simply referred to as a low melting point metal) on the outer peripheral surface of the liner, Although it may be sufficient to simply immerse the metal in the molten metal of the low melting point metal (claim 2), a film made of the low melting point metal is formed on the outer peripheral surface of the liner where the oxide film is removed at the same time as removing the oxide film existing on the outer peripheral surface of the liner. It is preferable to prevent the air from intervening between the surface of the liner from which the oxide film and the like have been removed and the film made of the low-melting-point metal (claim 3). Therefore, for example, by rubbing the outer peripheral surface of the liner in a state where the liner is immersed in the molten metal of the low melting point metal, the oxide film and the like on the surface of the liner are removed, and at the same time the outer peripheral surface is formed of the film made of the low melting point metal. (Claim 4). That is, by rubbing the outer peripheral surface of the liner in a state where the liner is immersed in the molten metal of the low melting point metal, the oxide film made of Al ₂ O ₃ or the like formed on the surface of the liner is removed and at the same time Since the low-melting metal immersed in the liner adheres to the surface (outer peripheral surface) of the liner from which the oxide film and the like have been removed, the air does not intervene between the liner surface and the low-melting metal, If the liner is pulled out of the low-melting-point metal melt, a film made of the low-melting-point metal is formed on its outer peripheral surface, and the air does not intervene between the liner surface and the film made of the low-melting-point metal. is there.

More specifically, a rubbing means is brought into contact with the outer peripheral surface of the liner in a state where the liner is immersed in the molten metal of the low melting point metal, and the liner is rotated in the circumferential direction in this state, or the rubbing is performed. By rotating the means around the outer periphery of the liner and rubbing the outer peripheral surface of the liner, an oxide film or the like existing on the outer peripheral surface of the liner is removed, and at the same time, a film made of a low melting point metal is formed on the outer peripheral surface ( Claim 5) The liner is heated to a predetermined temperature, and the outer peripheral surface of the liner is rubbed by a rubbing means to which the molten metal of the low melting point metal is adhered while maintaining the liner at the predetermined temperature, so that the outer peripheral surface of the liner is It is conceivable that the liner is immersed in a molten metal of the low melting point metal after removing the existing oxide film and the like and attaching the low melting point metal simultaneously (claim 6). It is.

Further, as another method for forming the coating of the low melting point metal on the outer peripheral surface of the liner, the liner is heated to a predetermined temperature, and a low melting point metal is applied to the outer peripheral surface of the liner while being maintained at the predetermined temperature. Shot blasting a shot bead or a wire blast made of a metal of claim 7 (claim 7), or heating the liner to a predetermined temperature, and holding the liner at a predetermined temperature with a low melting point metal on the outer peripheral surface of the liner. The formed solid film forming material is rubbed (claim 9), or a spray forming billet or a sintered billet made of an aluminum base material is used.
A liner is formed by extruding or drawing in a pure aluminum tube having an inner surface on which a film made of the metal having a low melting point is formed (claim 11). A liner may be cast by applying or spraying a film forming material obtained by adding a binder to low-melting-point metal powder (claim 12). The shot blasting of the shot bead or wire blast made of a low melting point metal on the outer peripheral surface of the liner is performed in a nitrogen gas, a carbon dioxide gas or an inert gas atmosphere (claim 8). It is preferable to heat to a temperature of up to 520 ° C (claim 10).

Further, in order to further enhance the adhesion with the aluminum alloy (base material) for forming the engine block, a number of linear depressions are formed on the outer peripheral surface of the liner when the liner is formed, and the outer peripheral surface of the liner is formed. Forming a film made of the low melting point metal on the outer surface of the liner (claim 13);
It is also conceivable to form a myriad of fine irregularities on the outer peripheral surface of the liner by pressing a heated surface roughening tool against the outer peripheral surface of the liner.
4). Further, as the aluminum base material forming the liner, an aluminum base composite material, a hypereutectic Al-Si alloy, or an Al-A
such as a sintered material such as l ₃ O ₃ -C particles can be cited (claim 15). The metal having a lower melting point than the liner (aluminum-based material) used to form a film on the outer peripheral surface of the liner is not limited as long as it does not adversely affect the corrosion resistance and strength of the die-cast product. However, specific examples thereof include zinc and a zinc alloy (claim 16).

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the illustrated embodiments. FIG. 1 is a schematic view showing an embodiment for explaining a step of forming a film made of a low melting point metal (zinc alloy) on the outer peripheral surface of a liner 1. FIG. 2 is an example of an aluminum alloy engine block 2. FIG. In the following description, the “metal having a lower melting point than the liner” is simply referred to as a “low-melting metal”.

The liner 1 is made of an aluminum alloy or an aluminum-based composite material having excellent wear resistance and heat resistance, a hypereutectic Al-Si alloy, or a sintered material such as Al-Al ₃ O ₃ -C particles. By using a method not specifically described herein, an engine block formed into a cylindrical shape having a required length and inner diameter, installed at a predetermined position in a mold cavity, and formed by die casting using an aluminum alloy. 2 is cast and integrated with the inner peripheral surface of the cylinder jacket 2a during the casting of the cylinder jacket 2a.
Finished with a. In the figure, reference numeral 2b denotes a water jacket for cooling the cylinder jacket 2a.

In order to integrate the liner 1 with the inner peripheral surface of the cylinder jacket 2a of the engine block 2 made of aluminum alloy with good adhesion, the liner 1 has an outer peripheral surface (all outer surfaces) in contact with the inner peripheral surface of the cylinder jacket 2a. A film made of a metal having a lower melting point than the aluminum-based base material forming the liner 1 is previously formed on the peripheral surface or the end surface of the top and bottom).

There are various methods for forming a film made of a low melting point metal on the outer peripheral surface of the liner 1, such as immersing the liner in a low melting point metal melt. By rubbing the outer peripheral surface of the liner in a squeezed state, an oxide film or the like made of Al ₂ O ₃ or the like present on the outer peripheral surface of the liner is removed, and at the same time, a film made of a low melting point metal is formed on the outer peripheral surface, It is preferable that the air does not intervene between the liner surface and the film made of the low melting point metal. Specifically, as shown in FIG. 1, the liner 1 is set on a mounting jig 3 and immersed in a molten metal (for example, a molten zinc alloy) 4 made of a metal having a lower melting point than the liner 1.
An appropriate rubbing means 5 such as a wire brush or stainless steel wool is pressed against the outer peripheral surface of the liner 1 to make contact therewith, and in this state, the liner 1 is rotated in the circumferential direction, or the rubbing means 5 is The outer circumference of the liner 1 is rubbed by the rubbing means 5 by rotating the planet around the outer circumference. Then, after the rubbing means 5 is separated from the outer peripheral surface of the liner 1, the liner 1 is pulled out of the low-melting-point metal melt 4. (Zinc alloy) is formed.

As another method for forming a film made of a low melting point metal on the outer peripheral surface of the liner, although not particularly shown, the liner is heated to a predetermined temperature of about 100 ° C. to 520 ° C. While maintaining the temperature, the outer peripheral surface of the liner is rubbed with a suitable rubbing means such as a wire brush or stainless steel wool to which a molten metal of a low melting point is adhered to remove an oxide film and the like present on the outer peripheral surface of the liner. And at the same time deposit a low melting metal,
Or dipping the liner in the molten metal of the low melting point metal,
Alternatively, a spray forming billet or a sintered billet made of an aluminum-based base material is put into a pure aluminum pipe having a coating made of a low melting point metal formed on an inner surface thereof, and is extruded or drawn to form a liner. The pure aluminum pipe is shaved off by post-processing to form a film made of low melting point metal on the outer surface of the liner, or the low melting point metal powder is adhered to the molding of the liner outer surface in the mold cavity by water glass or the like. It is conceivable to form a film made of a low-melting-point metal on the outer peripheral surface of the liner by applying a film-forming material to which an agent is added or by spraying a low-melting-point metal to cast a liner.

Further, as another method of forming a film made of a low melting point metal on the outer peripheral surface of the liner, it is conceivable to shot blast a shot bead or wire blast formed of a low melting metal on the outer peripheral surface of the liner. Can be In this case, when performing shot blasting of shot beads or wire blast (hereinafter abbreviated as shot material) on the outer peripheral surface of the liner, it is preferable to heat the liner to a predetermined temperature in advance. That is, the liner was heated to a predetermined temperature in advance so that the shot material formed of the low melting point metal was easily melted and thinned at the moment of collision with the outer peripheral surface of the liner, and the surface thereof was formed of the low melting point metal. The shot material is shot blasted.

The actual heating temperature varies depending on the physical properties such as the melting point of the liner to be used, but it is high enough not to cause blister on the liner, specifically, 100 ° C. to 450 ° C.
Is preferably set in the range. Below 100 ° C,
Even if the shot material formed of the low melting point metal collides with the outer peripheral surface of the liner, it is instantaneously melted and it is difficult to form a thin film. If the temperature is 450 ° C. or higher, the liner may be blistered or the liner may be deformed.

The size of the shot material formed of the low melting point metal and the pressure at the time of shot blasting on the outer peripheral surface of the liner are appropriately selected as appropriate according to the conditions such as the material and temperature of the liner and the low melting point metal. . Thus, when shot blasting a shot material made of a low melting point metal onto the outer peripheral surface of the liner, the shot blasting should be performed in a nitrogen gas, a carbon dioxide gas, or an inert gas atmosphere in order to minimize oxidation of the liner surface. Is preferred.

Further, as another method for forming a film made of a low melting point metal on the outer peripheral surface of the liner, it is conceivable to rub a solid film forming material formed of a low melting point metal on the outer peripheral surface of the liner. Also in this case, it is preferable to heat the liner to a predetermined temperature in advance and rub the solid film forming material while maintaining the liner at the predetermined temperature. That is, the liner is heated to a predetermined temperature in advance so that the solid film forming material is instantaneously dissolved and thinned when the outer peripheral surface of the liner is rubbed with the solid film forming material formed of the low melting point metal. A solid film-forming material formed of a low-melting metal is rubbed against the outer peripheral surface of the liner while being maintained at a predetermined temperature. The specific temperature is preferably set in the range of 150 ° C to 430 ° C. Although it is not impossible by rubbing at high speed and high pressure even at 150 ° C. or less, the equipment cost increases,
Basically, at 150 ° C or lower, an appropriate metal film cannot be formed even by rubbing a solid film-forming material formed of a low melting point metal. The film-forming material melts out, making it impossible to form a proper metal film. At this time,
It is preferable that the solid film forming material formed of the low melting point metal is also heated to a predetermined temperature higher than room temperature.

In order to further enhance the adhesion with the aluminum alloy (base material) for forming the engine block, a number of linear depressions are formed on the outer peripheral surface of the liner 1 when the liner 1 is formed. A coating made of a low-melting-point metal is formed on the outer peripheral surface, or as shown in FIG. 3, a wire brush 6 heated on the outer peripheral surface of the liner 1 in which a coating made of a low-melting-point metal is formed on the outer peripheral surface in advance. It is preferable that countless fine irregularities are formed on the outer peripheral surface of the liner 1 by pressing. in this case,
In particular, in the former case, it is preferable that a large number of linear depressions formed on the outer peripheral surface of the liner 1 are formed along the direction in which the molten metal flows when the liner is installed in the cavity of the mold. Specifically, in many cases, the liner 1 is installed in the cavity of the mold so that its axial direction is along the flow direction of the molten metal, so that many linear depressions are formed along the axial direction of the liner 1. Is preferred. In the latter case, the wire brush 6 is heated to about 100 ° C. to 520 ° C. with a gas burner 7 or the like so that the coating made of the low melting point metal formed on the outer peripheral surface of the liner is easily softened. It is preferable to rotate the liner 1 or the wire brush 6 in directions opposite to each other in a state where the liner 1 or the wire brush 6 is pressed against the outer peripheral surface of the liner 1. As described above, by forming a large number of linear dents or forming countless fine irregularities on the outer peripheral surface of the liner 1, the air on the outer peripheral surface of the liner 1 is filled when the molten metal is filled in the mold cavity. The escape of gas) is improved, and the molten metal (aluminum alloy base material) is completely in the outer peripheral surface of the liner, that is, the air (gas) does not exist between the molten metal (aluminum alloy base material) and the outer peripheral surface of the liner. It is considered that as a result, the adhesion between (the outer peripheral surface of) the liner 1 and the aluminum alloy (base material) is improved.

Thus, when the engine block 2 is die-cast, it is possible to perform casting under the same casting conditions as in the case of casting a conventional cast iron liner. The liner 1 on which the coating is formed is placed at a predetermined position in a mold cavity, and is die-cast using an aluminum alloy. Then, the engine block 2 integrated with the liner 1 in a state of being cast into the inner peripheral surface of the cylinder jacket 2a is cast.

Next, a specific embodiment will be described. <Example 1> A liner 1 was made of a hypereutectic Al-Si alloy (S
i23wt%, Cu4wt%, Mg1.2wt%, Fe
0.2 m%, balance Al), length is 120 m
m, the inner diameter was 86 mm, and the outer diameter was 94 mm. Set this liner 1 on the mounting jig 3 and
The liner 1 is rotated at a speed of 180 rpm while being immersed in the molten zinc alloy 4 kept at 0 ° C. and in contact with the rubbing means 5 made of a wire brush on the outer peripheral surface.
The outer peripheral surface of the liner 1 was rubbed for 10 seconds. Thereafter, the rubbing means 5 is separated from the outer peripheral surface of the liner 1 and
From the molten zinc alloy 4. Then, a zinc alloy film having a thickness of about 0.5 mm was formed on the outer peripheral surface of the liner 1. The liner 1 was set at a predetermined position in the mold cavity, and the engine block 2 was die-cast using an aluminum alloy of the ADC 12 under the same casting conditions as those for casting a conventional cast iron liner.

FIGS. 4A to 4C show the results of observing the adhesion between the liner 1 and the cylinder jacket 2a of the engine block 2. FIG. (A) shows the boundary between the liner 1 and the cylinder jacket 2a in the vicinity of the engine block on the deck side (the surface indicated by a in FIG. 2), and (b) shows the liner 1 and the cylinder jacket 2a in the center of the bore. Indicates the border with the part, and
(C) shows a boundary portion between the liner 1 and the cylinder jacket 2a in a portion near the journal side (the surface indicated by b in FIG. 2) of the engine block. From these observation results, not only does the boundary between the aluminum alloy forming the cylinder jacket 2a portion of the engine block and the liner 1 made of the aluminum base material become indistinct as the distance from the vicinity of the deck side increases,
No trace of the zinc alloy film formed on the outer peripheral surface of the liner 1 is found. This is presumably because the molten aluminum alloy forming the engine block came into contact with the outer peripheral surface of the liner, so that the zinc alloy film adhered to the outer peripheral surface of the liner was alloyed with aluminum.

<Embodiment 2> Using a liner similar to that in Embodiment 1, a wire brush having a zinc alloy melt adhered to the outer peripheral surface of the liner preheated to about 500 ° C. in an electric furnace while being heated, and pressed against the liner. , The liner and the wire brush were rotated in opposite directions for 30 seconds. Thereafter, the liner was immersed in the molten zinc alloy for 30 seconds and pulled up. As a result, a thickness of about 150 to 200
A μm zinc alloy film was formed. FIG. 5 shows a microphotograph of a cross section of the metal structure on the surface of the liner on which the zinc alloy film is formed.

<Embodiment 3> Aluminum alloy (ADC1)
The test piece die-cast using 2) is regarded as a liner, and a zinc alloy (Zn 99 wt.
%, Pb, Fe, Cu 1 wt%).
A liner having a size of 6 mm to 0.8 mm was used as a shot material, the liner was heated to about 430 ° C., and in this state, the shot material was shot blasted on the outer peripheral surface of the liner. As a result, there was no generation of dust that pollutes the environment, the outer peripheral surface of the liner was roughened unevenly, and a zinc alloy film having a thickness of about 100 to 150 μm was formed on the outer peripheral surface. This is because the liner (test piece) is preheated during shot blasting, so that the shot material instantaneously melts and forms a film before it becomes dust, and the surface of the preheated liner is softened and shot. It is considered that unevenness was easily formed by the collision of the material. FIG.
2 shows a photograph of the surface of the zinc alloy film formed on the outer peripheral surface of the liner.

<Example 4> Similar to Example 3, a die-cast product using an aluminum alloy (ADC12) was regarded as a liner, and a solid film formed into a substantially rod shape using a zinc alloy (ZD2). Wood was used. The liner was heated to about 380 ° C., and in this state, the solid film forming material was rubbed against the outer peripheral surface of the liner. As a result, a thickness of about 150 to 200 μm
Was formed. FIG. 7 shows a microphotograph of a cross section of the metal structure on the surface of the liner on which the zinc alloy film is formed.

Looking at the metallographic structure of FIG. 7, it is observed that the boundary between the liner and the zinc alloy film formed on the surface is not clear. This is because the oxide film (Al ₂ ) existing on the surface of the liner when the zinc alloy film was formed.
It is considered that O ₃ ) was destroyed and the liner and the zinc alloy film were alloyed.

Example 5 A linear recess having a depth of 1 mm and a width of 1 mm was formed on the outer peripheral surface of a liner prepared in the same manner as in Example 1 at a pitch of 3 mm along the longitudinal direction of the liner. A zinc alloy film having a thickness of about 0.5 mm was formed on the outer peripheral surface of the liner in the same manner as in Example 1. This liner was placed at a predetermined position in a mold cavity, and an engine block was die-cast using an ADC12 aluminum alloy under the same casting conditions as those for casting a conventional cast iron liner. FIG. 8 shows a microphotograph of a metal structure cross section at the boundary between the die-cast engine block and the liner. From this photograph, it can be seen that the engine block and the liner are integrated with good adhesion.

<Example 6> A zinc alloy film having a thickness of about 0.5 mm was formed on the outer peripheral surface of the liner in the same manner as in Example 1, and the liner was preheated to about 500 ° C. The wire brush was pressed while being heated to about 400 ° C. with a gas burner, and in this state, the liner and the wire brush were rotated in opposite directions. As a result, the surface roughness Ra =
Irregularities of 13 μm, Rz = 60 μm, and Rmax = 117 μm were formed. FIG. 9 shows a graph of the measured surface roughness.

[0031]

According to the method of manufacturing an engine block according to the present invention, the liner is formed of an aluminum-based base material, and the outer peripheral surface of the liner has a lower melting point than the aluminum-based base material forming the liner. A metal coating was formed, and the liner was installed at a predetermined location in the mold cavity and cast by die casting using an aluminum alloy. When the molten metal of the aluminum alloy that forms the engine block comes into contact with the outer peripheral surface of the liner when the liner made of cast iron is cast, the low-melting metal film adhered to the outer peripheral surface of the liner is alloyed with aluminum, Therefore, the molten aluminum alloy covers the outer peripheral surface of the liner. Therefore, there is no oxide film or the like between the outer peripheral surface of the liner made of the aluminum base material and the engine block made of the aluminum alloy. As a result, the liner made of the aluminum base material is adhered to the engine block made of the aluminum alloy. It becomes possible to integrate well.

In addition, in order to form a film made of a low melting point metal on the outer peripheral surface of the liner, it is only necessary to rub the outer peripheral surface of the liner while the liner is immersed in the molten metal of the low melting point metal. The low-melting-point metal film can be formed thinly and uniformly on the outer peripheral surface of the liner by a simple and inexpensive method.

According to the method for manufacturing an engine block according to the sixth aspect of the present invention, compared to the method for manufacturing an engine block according to the fourth or fifth aspect, a part of the liner is formed of a molten metal having a low melting point. As a result, it becomes easy to keep the components of the low-melting metal melt constant for a long period of time.

Further, according to the method for manufacturing an engine block according to the seventh to tenth aspects, the following operation and effect can be obtained. When the low melting point metal film is formed, the outer peripheral surface of the liner and the low melting point metal film are alloyed and integrated. Therefore, when the low melting point metal film formed on the outer peripheral surface of the liner is used as an intermediate member and is joined to an engine block using an aluminum alloy as a base material, it is possible to integrate the engine block with good adhesion. When forming a low-melting metal film on the outer peripheral surface of the liner, there is no need to dissolve the material (shot material or solid film-forming material) that is the source of the low-melting metal film (there is no need to dissolve), so it is safe In addition to being environmentally friendly and energy saving, the number of processes is small, the equipment is simple, and continuous operation is possible. When forming the low-melting metal film on the outer peripheral surface of the liner, there is no fear that the liner has a bad influence such as blistering or deformation. Even if there is a defect such as a void in the film forming surface of the liner, it can be improved by the low melting point metal film.

Further, according to the method of manufacturing an engine block according to the thirteenth aspect, when the molten metal is filled in the cavity of the mold, the escape of air (gas) on the outer peripheral surface of the liner is improved. Alloy base material) is in perfect contact with the outer surface of the liner, that is, in a state where air (gas) does not exist between the molten metal (aluminum alloy base material) and the outer surface of the liner. An alloy (base material) can be integrated with good adhesion.

According to the engine block manufacturing method of the present invention, innumerable fine irregularities can be easily and relatively coarsely formed on the outer peripheral surface of the liner. Therefore, for the same reason as in the case of the thirteenth aspect, the liner made of the aluminum-based base material can be integrated with the aluminum alloy engine block with better adhesion.

[Brief description of the drawings]

FIG. 1 shows an embodiment according to claim 4 of the present invention,
FIG. 4 is a schematic diagram for explaining a step of forming a low-melting metal film on the outer peripheral surface of the liner.

FIG. 2 is a sectional view showing an example of an engine block.

FIG. 3 is a schematic view showing an embodiment according to claim 14 of the present invention.

FIG. 4 shows a method according to claim 5 of the present invention (Example 1).
The microphotograph of the cross section of the metal structure at the boundary portion between the engine block and the liner, which is die-cast by (a) is a portion near the deck side of the engine block,
(B) is a central portion of the bore, and (c) is a portion of the engine block near the journal.

FIG. 5 shows a method according to claim 6 of the present invention (second embodiment).
5 is a photograph showing the surface of a low-melting metal film (zinc alloy film) formed on the outer peripheral surface of the liner.

FIG. 6 shows a method according to claim 7 of the present invention (third embodiment).
5 is a photograph showing the surface of a low-melting metal film (zinc alloy film) formed on the outer peripheral surface of the liner.

FIG. 7 shows a method according to claim 9 of the present invention (Example 4).
5 is a microphotograph showing a metallographic cross section of a low-melting metal film (zinc alloy film) formed on the outer peripheral surface of the liner.

FIG. 8 is a microphotograph of a cross section of a metal structure at a boundary portion between an engine block and a liner die-cast by a method according to claim 13 of the present invention (Example 5).

FIG. 9 is a graph showing the measured surface roughness of fine irregularities formed on the outer peripheral surface of the liner by the method according to claim 14 of the present invention (Example 6).

[Explanation of symbols]

1: liner 2: engine block 4: low melting metal (zinc alloy) molten metal 5: rubbing means 6: wire brush 7: gas burner

Claims (16)

[Claims] 1. A liner is formed of an aluminum-based base material, and a coating made of a metal having a lower melting point than the aluminum-based base material forming the liner is formed on the outer peripheral surface of the liner. A method of manufacturing an engine block, wherein the engine block is installed at a predetermined position in a cavity and is cast by die casting using an aluminum alloy. 2. The method of manufacturing an engine block according to claim 1, wherein the liner is immersed in a molten metal of the low melting point metal to form a film made of the low melting point metal on an outer peripheral surface thereof. 3. An oxide film or the like existing on the outer peripheral surface of the liner is removed, and at the same time, a film made of the low melting point metal is formed on the outer peripheral surface of the liner from which the oxide film has been removed. 2. The method for manufacturing an engine block according to claim 1, wherein air does not intervene between the liner surface and the coating made of the low melting point metal. 4. An outer peripheral surface of the liner is rubbed in a state where the liner is immersed in a molten metal of the low melting point metal, thereby removing an oxide film and the like existing on an outer peripheral surface of the liner and simultaneously forming the low melting point metal. 2. The method for manufacturing an engine block according to claim 1, wherein a film comprising: 5. A rubbing means is brought into contact with the outer peripheral surface of the liner in a state where the liner is immersed in the molten metal of the low melting point metal, and in this state, the liner is rotated in the circumferential direction or the rubbing means is used. By rotating the planetary around the outer periphery of the liner and rubbing the outer peripheral surface of the liner, an oxide film or the like existing on the outer peripheral surface of the liner is removed, and at the same time, a film made of the low melting point metal is formed. A method for manufacturing an engine block according to claim 1. 6. The liner is heated to a predetermined temperature, and the outer surface of the liner is rubbed by a rubbing means to which the molten metal of the low melting point metal is adhered while maintaining the liner at the predetermined temperature, so that the outer surface of the liner is After removing the existing oxide film and the like and attaching the low melting point metal at the same time, by immersing the liner in the molten metal of the low melting point metal,
2. The method for manufacturing an engine block according to claim 1, wherein a film made of said low melting point metal is formed on an outer peripheral surface thereof. 7. A method in which the liner is heated to a predetermined temperature, and a shot bead or a wire blast made of the low melting point metal is shot blasted on an outer peripheral surface of the liner while maintaining the liner at a predetermined temperature, 2. The method for manufacturing an engine block according to claim 1, wherein a coating made of the low melting point metal is formed on an outer peripheral surface of the liner. 8. The engine block according to claim 7, wherein shot beads or wire blast made of the low melting point metal is shot blasted on an outer peripheral surface of the liner in an atmosphere of nitrogen gas, carbon dioxide gas or inert gas. Production method. 9. A method of heating the liner to a predetermined temperature and rubbing a solid film-forming material formed of the low melting point metal on an outer peripheral surface of the liner while maintaining the liner at the predetermined temperature. 2. A coating comprising the low melting point metal formed on an outer peripheral surface of a liner.
A method for manufacturing the described engine block. 10. The method according to claim 10, wherein the liner is previously heated to 100 ° C.
10. The method for manufacturing an engine block according to claim 6, wherein the heating is performed to a temperature of about ℃. 11. A spray forming billet or sintered billet made of an aluminum-based base material is put into a pure aluminum pipe having an inner surface on which a film made of a metal having a low melting point is formed, and is extruded or drawn to form a liner. 2. The method according to claim 1, wherein a coating made of the low melting point metal is formed on an outer peripheral surface of the liner. 12. The outer periphery of the liner is formed by applying or spraying a film forming material obtained by adding a binder to the powder of the low melting point metal on the liner outer peripheral surface forming portion in the mold cavity, and casting the liner. 2. The method for manufacturing an engine block according to claim 1, wherein a film made of said low melting point metal is formed on a surface. 13. The liner according to claim 1, wherein a plurality of linear depressions are formed on an outer peripheral surface of the liner when the liner is formed, and a film made of the low melting point metal is formed on an outer peripheral surface of the liner. A method for manufacturing the described engine block. 14. A coating made of the low melting point metal is formed on the outer peripheral surface of the liner, and a heated surface roughening tool is pressed against the outer peripheral surface of the liner, thereby forming a myriad of fine irregularities on the outer peripheral surface of the liner. 2. The method for manufacturing an engine block according to claim 1, wherein said method is performed. 15. An aluminum-based base material forming the liner is made of an aluminum alloy, an aluminum-based composite material, a hypereutectic Al-Si alloy, or an Al-based alloy.
2. The method for manufacturing an engine block according to claim 1, wherein the method is a sintered material of Al ₃ O ₃ —C particles. 16. The method according to claim 1, wherein the low melting point metal is zinc or a zinc alloy.