JPS6045982B2 - Method of manufacturing engine block water jacket core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a water jacket core for an engine block used for casting an engine block in which a water jacket waterway is formed between cylinders.

When casting products using a core, if the core does not have any particularly wide or narrow parts, there will be no problems in production and use, but if there is a water jacket between the cylinders, such as in an engine block, In the case of castings with narrow waterways, there is a significant difference between the part of the water jacket that surrounds the outer periphery of each cylinder that forms the wide waterway part and the part that forms the narrow waterway part between the cylinders. A core having a narrow part for forming a part has the following problems in use.

That is, when a conventional sand mold core is used, troubles such as breakage, seizure, or blindness occur in the narrow portion during casting, and the intended waterway is likely to be blocked. It goes without saying that such an engine block is likely to cause partial heating or deformation of the cylinders during use. The cause of such casting troubles is that the saw body is molded from resin-coated sand (hereinafter referred to as silica sand/resin-coated sand), which is commonly used silica sand coated with resin, due to the molding method. Although it is simple, the strength of the narrow portion of the obtained core is low, the degree of sand filling in this portion is low, and the heat resistance is also low.

The present invention was made in order to solve these problems, and the water jacket core is molded using partially different molding sand, so that the strength, heat resistance, etc. required especially in the narrow part is improved. The purpose of this method is to provide a method for easily and reliably manufacturing a core that fully satisfies the following: The core part is molded using resin-coated sand made by coating zircon sand with resin, and the core part is attached to a predetermined position in a separately manufactured water jacket core mold, and then a wide water channel part is formed. In order to mold a thick-walled core part, the core mold is filled with silica sand/resin coated sand and molded integrally with the core part.

Embodiments of the present invention will be described in detail below.

First, the engine block castings cast using the core according to the present invention will be illustrated and explained.
Second cross-sectional view of the engine block taken along a plane passing through each narrow waterway between a plurality of cylinders arranged in parallel.
The figure shows a longitudinal sectional view of the main part of the engine block when cut along a plane passing through the axes of each of a plurality of cylinders arranged in parallel. As shown in the figure, there is a wide water channel 2 surrounding the outer periphery of each cylinder a, and a narrow water channel 1 between each cylinder a.
A water jacket b is formed by this. When forming such a water jacket b by casting, it is naturally necessary to use a water jacket core to form the water channels 1 and 2, but as mentioned earlier, the water jacket core is However, the space in the first part of the waterway is extremely narrow, and if the waterways 1 and 2 are molded using ordinary silica sand/resin-coated sand in the conventional manner,
As mentioned above, since the core portion forming the water channel 1 portion during casting is thin, casting troubles are likely to occur.
Accordingly, in the present invention, when molding a cast water jacket core having such water channels 1 and 2, first, a thin wall forming the water channel 1 portion located between a plurality of parallel cylinders a is formed. Resin-coated sand (hereinafter referred to as Zircon 9 resin-coated sand) in which the core part of the shape is coated with resin with zircon sand that has excellent heat resistance and seizure resistance.

). In this case, the core portion does not need to be completely hardened and molded, and it is sufficient that it is formed to such an extent that it can be fitted and set in a predetermined position of a water jacket core mold, which will be described later. Next, the core portion is fitted and set in a predetermined position of a water jacket core mold that has been separately manufactured in advance. In this case, the core mold can be freely selected from a metal mold, a wooden mold, etc.

Then, in order to form a thick core part for forming the other two water channels in the core mold, ordinary silica sand/resin coated sand is filled by means of plowing or the like. By doing so, the core portion formed by the previously set zircon/resin coated sand and the other core portions formed by the silica sand/resin coated sand are easily and reliably molded into one piece. The water jacket core formed in this way is combined with a mold that can cast each cylinder a, the outer wall of the crankcase, etc. as required.
In the case where the engine block shown in the figure is cast by a conventional method, the core part forming one part of the narrow waterway located between the plurality of parallel cylinders a is made of conventional molding such as silica sand or resin coated sand. Instead of sand, it is molded using zircon resin-coated sand, which has a high packing density and high strength and heat resistance, so it does not cause any trouble such as breakage, seizure, or misalignment. This ensures that only one narrow channel section is cast.

FIG. 3 shows an example of the water jacket core according to the present invention, where the portion 3 corresponding to the portion forming the narrow waterway between each cylinder is molded with zircon resin coated sand. On the other hand, there is a part 4 corresponding to a part forming a wide water channel surrounding the outer periphery of each cylinder.
is modeled using silica sand and resin coated sand. As explained above, according to the present invention, the autojacket core is made of zircon-resin coated sand that has excellent heat resistance and seizure resistance. can be manufactured easily and reliably, and if cast using this core, the breakage, seizure, and misalignment that frequently occur in the core part that forms the narrow waterway part of each cylinder, which was a problem in the past, can be avoided. It is possible to reliably prevent such troubles. As described above, the method for producing a water jacket core according to the present invention has great industrial utility value.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the engine block taken along a plane that passes through each narrow waterway between a plurality of cylinders arranged in parallel, and Figure 2 shows the axis of each of the cylinders arranged in parallel. FIG. 3, which is a vertical sectional view of the main part of the engine block when cut along a plane passing through the engine block, is a perspective view showing an example of the water jacket core according to the present invention. 1... Narrow waterway part, 2... Wide waterway part, 3...
- Core portion forming a narrow water channel portion, 4... Core portion forming a wide water channel portion, a... Cylinder, b... Water jacket, c... Cylindrical space.

Claims (1)

[Claims] 1. A method for manufacturing a core for forming a water jacket for an engine block having a narrow channel portion between a plurality of cylinders arranged in parallel and a wide channel portion surrounding the outer periphery of each cylinder, the method comprising: first forming a water jacket in the engine block; The thin-walled core part that forms the mold is molded using resin-coated sand made by coating zircon sand with resin, and the core part is mounted in a predetermined position in a water jacket core mold that has been separately manufactured in advance. In order to mold a thick-walled core part that forms a wide waterway part, the core mold is filled with resin-coated sand in which silica sand is coated with a resin, and the core part is molded integrally with the core part. A method for manufacturing water jacket cores for engine blocks.