JPH0331479Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a cylinder block casting apparatus having a water jacket portion.

(Prior art) Engine cylinder blocks are divided into open-deck type and closed-deck type, and the open-deck type cylinder block has a water jacket formed inside the cylinder block and a water jacket formed inside the cylinder head. In a closed deck type cylinder block, a water jacket formed in the cylinder block and a water jacket formed in the cylinder head are connected through a communication hole formed in the deck portion.

Further, the cylinder block is generally made by casting an aluminum alloy, but the water jacket part is formed by a core.

By the way, in the case of open deck type cylinder blocks, since the water jacket is open directly on the deck surface, the core can be removed after casting, so it is possible to use an aluminum alloy core and use the die casting method. We are currently conducting casting.

On the other hand, in the case of a closed deck type cylinder block, only the communication hole of the water jacket is opened on the deck surface, so the core cannot be removed after casting, and a sand core is used. Gravity casting is used because it easily breaks under pressure. However, sand cores cannot be reused and are easily broken during casting, and gravity casting has the disadvantage of requiring longer casting time than die casting.

Therefore, the present applicant has previously proposed a method that enables even a closed deck type cylinder block to be cast by die casting using an aluminum alloy core. That is, a core in the shape of the water jacket part of a cylinder block is molded from aluminum alloy, this core is set in a mold, and this aluminum alloy core is connected between the outer surface and the inner surface of the mold. A cylinder block body made of aluminum alloy is cast using the die-casting method as a cavity for forming the cylinder block body between the cylinder blocks, and then a communication hole to the deck surface is drilled by machining, and then a sleeve is press-fitted into the inner peripheral surface of the cylinder block. In this method, a water jacket is formed between the sleeve and the cylinder block.

(Problem to be solved by the invention) However, according to the method described above, since the aluminum alloy core has a bulge that forms a water jacket, it is difficult to remove the core after casting. There are aspects that cannot necessarily be said to be easy, such as requiring strong removal force or special jigs.

(Means for Solving the Problems) In order to solve the above problems, the present invention has a mold with a length approximately equal to the height of the water jacket on the outer periphery of the bore portion for forming the inner peripheral surface of the cylinder block. A protrusion was formed, and a recess into which the protrusion entered was formed on the inner peripheral surface of the core.

(Function) Since the core has a thin walled part that becomes a mechanically weak part corresponding to the protrusion provided in the bore part,
By applying an external force to the core after casting, the core can be easily split.

(Example) An example of the present invention will be described below based on the accompanying drawings.

Figure 1 is a cross-sectional view of the main parts of the molding device in the mold matching state before pouring molten aluminum alloy, Figure 2 is a perspective view showing the relationship between the core and the bore, and Figures 3 and 4 are for casting. This is a sectional view of the main parts at the time, and a mold is constituted by molds 1, 2, and 3, a bore part 4 and a pin part 5 are integrally provided in the mold 1, and an aluminum alloy plate is formed on the outside of the bore part 4. The cores 6 are set in close contact. The core 6 is formed with a bulge 6a for molding a water jacket portion, and a cavity 7 is formed between the molds 1, 2, 3 and the aluminum alloy core 6. Furthermore, four protrusions 8 are provided at equal intervals on the outer periphery of the bore portion 4 and have a length approximately equal to the height of the water jacket, and the protrusions 8 enter into the inner peripheral surface of the core 6. A recess 9 is formed, and the recess 9 forms a thin part 10 in the core 6 which becomes a mechanically weak part.

Insert the core 6 having the shape described above into the bore portion 4,
The molds 1, 2, and 3 are fitted together, and molten aluminum alloy is poured under pressure (die-casting) into the cavity 7 formed between the molds. After the molten aluminum alloy poured into the insides of the molds 1, 2, 3 and the outside of the core 6 is cooled and solidified, the molds 1, 2, 3 are released.
In this mold release, since the protrusion 8 formed in the bore part 4 of the mold 1 is formed in the drawing direction, the mold can be released smoothly, and the molds 1, 2,
By releasing 3 from the mold, the cylinder block body 11
is cast, and the core 6 remains on the inner circumference of the cylinder block body 11, as shown in FIG.

Therefore, the core 6 is removed from the cylinder block body 11 as shown in FIG. In other words, the tip of the chuck jig 12 is placed on the flange portion 6b of the core 6,
Close the chuck jig 12. Then, since the core 6 has a fragile thin part 10 formed by the recess 9 as described above, the core 6 breaks into a plurality of pieces at this thin part 10. Therefore, these divided pieces were removed from the cylinder block body 11, and
Thereafter, by machining, the hole 11a formed by the pin portion 5 is made to communicate with the inner circumferential surface of the cylinder block body 11 (the inner circumferential surface that becomes the water jacket), and the cylinder block body 11 is formed as necessary.
After grinding the inner circumferential surface, the sleeve 12 is press-fitted into the cylinder block body 11 as shown in FIG. 7, thereby creating a cylinder in which a water jacket part 14 is formed on the outside of the sleeve 13 and on the inside of the cylinder block body 11. Get a block.

In the illustrated example, a recess is formed on the inner periphery of one core so that the core can be easily broken later. The cores may be placed individually in each. In this case, the protrusions will fit into the recesses formed between the individual cores.

(Effects of the invention) As explained above, according to the invention, the aluminum alloy core can be easily removed from the cylinder block body after casting, so even if the cylinder block is of a closed deck type, the cylinder block is made of aluminum alloy. It can be cast using a die-casting method using a core, and products of good quality can be efficiently produced.

[Brief explanation of the drawing]

Figure 1 is a sectional view before casting, Figure 2 is a perspective view of the bore and core, Figures 3 and 4 are sectional views of the main parts of the mold during casting, and Figure 5 is the cylinder block body. 6 is a sectional view showing a state in which the core is removed, and FIG. 7 is a sectional view of the cylinder block. In addition, in the drawing, 1, 2, 3 are the molds, 4 is the bore part, and 6
1 is a core, 7 is a cavity, 8 is a protruding portion, 9 is a recessed portion, 10 is a thin wall portion, and 11 is a cylinder block body.

Claims (1)

[Scope of utility model registration request] In a cylinder block casting apparatus having a water jacket portion consisting of a mold and a core, the outer periphery of the bore portion of the mold that forms the inner peripheral portion of the cylinder block has a length approximately equal to the height of the water jacket. A protrusion is formed, the core is made of aluminum alloy and has a bulge that forms a water jacket part, and a recess into which the protrusion enters is formed on the inner periphery of the core. A cylinder block casting device characterized by: