JPS6323869B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sand casting a cylinder block in a multi-cylinder engine in which a number of cylinders are arranged parallel to each other.

Generally, in a multi-cylinder engine, a cooling water jacket is formed between each cylinder bore, so the bore pitch becomes large and the length of the engine in the direction in which the cylinders are parallel becomes large.

For this reason, in recent years, in order to reduce the bore pitch, adjacent bores are connected and the intermediate cooling water jacket part is eliminated.

However, when producing this type of cylinder block by sand mold casting, the sand mold core, which corresponds to the cooling water jacket, becomes long in the parallel direction of the bores, and there is a risk that this sand mold core may be deformed by the casting pressure. It was hot.

For this reason, in practice, as shown in FIG. 4, means for reinforcing the sand mold core 11 by forming a bridge part 11a in the middle of the sand mold core 11 by partially providing one with a large bore pitch, or a fifth As shown in the figure, a method has been taken in which the sand mold core 11 is reinforced with a core metal 17 and cast into the bore connection portion.

However, in the former case, there is a part with a large bore pitch, so it is not possible to make it sufficiently compact.
In addition, in the latter case, the core metal 17 protrudes into the cooling water jacket part and is cast, which becomes an obstacle when the sand mold core 11 is torn out from the casting hole 18 after casting. Ta.

The present invention aims to solve the problems of the conventional casting method and to provide a method of sand casting a cylinder block with a small bore pitch.

An example of the procedure for implementing the method of the present invention will be described below based on the drawings.

Figure 1 shows a side view of a water-cooled four-cylinder diesel engine, which is an example of a multi-cylinder engine. A cylinder block 4 is provided in which cylinders are arranged parallel to each other, and a cylinder head 7 equipped with groups of intake and exhaust valves 5 and 6 is provided above the cylinder block 4.

As shown in FIG. 2, the cylinder block 4 is
It is sand cast into a shape in which all the cylinder bores 3 are connected to each other and a cooling water jacket 8 is provided around the outer periphery of these bore groups, and the sand mold is shown in FIG.

That is, as a mold for this cylinder block 4, a sand mold 9 for forming the outer shape, a sand mold core 10 for forming the inside of the bore 3, and a sand mold core 11 for forming the cooling water jacket 8 are used. A pair of cast holes 12 are formed in one short side of the outer wall of the cylinder block so as to be continuous with the longitudinal parts on the left and right sides of the sand mold core 11, and at the center of the short side of the other outer wall. Also cast hole 13
is formed. Reinforcement mandrel rods 14, 14 are embedded in the longitudinal portion of the sand mold core 11, respectively, and one end of each mandrel 14 has a pair of cast holes 1.
It is penetrated by 2.12.

The mold configured as described above has a sand mold core 11
Since the longitudinal portion of the core bar 14 is reinforced by embedding the mandrel rod 14, it will not be deformed by casting pressure. After casting, the mandrel rods 14 are pulled out from the sand mold core 11 through the casting holes 12, respectively, and then the core 11 is collapsed from the casting holes 12 and 13. In this case, by pulling out the mandrel 14 first, the core 11 is likely to collapse.
Casting sand can be easily discharged.

The cast holes 12 and 13 are closed with plugs 15 and 16 to keep the jacket 8 watertight.

As explained above, according to the sand casting method of the present invention, there is no need to form a large part of the bore pitch for reinforcing the core as shown in FIG. By reducing the length of the engine, the engine itself can be made smaller. Moreover, as shown in Fig. 5, the core is not reinforced by using a cast-in mandrel, which would prevent the sand from being drawn out, but rather from the point where the reinforcing mandrel is pulled out.
Since the sand core tends to collapse, the core can be easily and completely removed after casting.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially cutaway side view of the engine, Fig. 2 is a cross-sectional plan view of the cylinder block, Fig. 3 is a cross-sectional plan view of the mold for casting the cylinder block, and Fig. 4 is a cross-sectional plan view of the cylinder block casting mold. 5 and 5 are plan views of molds used in the conventional casting method, respectively. 3...Cylinder bore, 4...Cylinder block, 8...Cooling water jacket, 11...Sand mold core, 12...Cast hole, 14...Reinforcement mandrel.

Claims (1)

[Claims] 1. In a sand casting method for a cylinder block 4 in which a large number of cylinder bores 3 are arranged parallel to each other and a cooling water jacket 8 is provided around a group of these bores, all the cylinder bores 3
The sand mold core 11 of the cooling water jacket 8 is formed so that adjacent ones of the cylinder blocks 3 are connected to each other, and a cast hole 12 extending toward the longitudinal part of the sand mold core 11 is formed in a portion corresponding to the outer wall of the cylinder block 4.
A reinforcing mandrel 14 is embedded in the sand mold core 11 along its longitudinal portion, and after casting, the reinforcing mandrel 14 is pulled out from the cast hole 12 to collapse the sand mold core 11. Sand casting method for cylinder blocks in multi-cylinder engines.