JP3215520B2 - Casting method of cylinder block - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for casting a cylinder block constituting an engine of an automobile or the like.

[0002]

2. Description of the Related Art FIG. 6 shows an entire cylinder block constituting a main body of a general reciprocating type four-cycle four-cylinder engine for an automobile.
Is manufactured by integrally molding the upper bore portion 2 and the lower crankcase portion 3 by casting.

[0003] bore 2, 4 forming cylinders were each piston (not shown) is parallel four bores 4 which are slidably inserted, a flat upper end face of the bore portion 2, not shown cylinder It is a cylinder head joining surface 5 to which the head is joined. Also, the left and right end surfaces are respectively a case joining surface 8 to which a transmission case (not shown) is joined.
And a cover joining surface 9 to which a side cover (not shown) is joined.
It has become.

Each of the bores 4 has a cylindrical sleeve 6 formed of a material having high wear resistance such as FC (grey cast iron).
It is formed by being cast. In addition, bore part 2
Is formed with a water jacket 7 surrounding each bore 4. The water jackets 7 are formed in a cylindrical shape that is coaxial with the sleeves 6 along the periphery of each sleeve 6 and are connected to form one water jacket 7. As can be seen from FIG. 7, the portion of the bore portion 2 where the water jacket 7 is formed has an inner wall 2A on the bore 4 side and an outer wall 2B on the opposite side from the water jacket 7 as a boundary. You.

On the other hand, the inner space of the crankcase portion 3 communicates with each of the bores 4 so that a crankshaft (not shown) is accommodated therein. The crankshaft is
The bores 4 are arranged along the direction in which the bores are arranged, and both ends thereof are rotatably supported by the crankcase portion 3 and are connected to the piston via a connecting rod (not shown).

[0006] The cylinder block 1 is integrally formed by casting as described above. In this case, however, high dimensional accuracy and a good casting surface can be obtained.
A molten metal (aluminum alloy or the like), which is a molten material, is put into the cavity of the assembled mold from the lower side, that is, the crankcase portion 3 side, and is cast.

FIGS. 8 and 9 schematically show the structure of the above-mentioned mold, in which a fixed mold 11 for forming the lower surface 10a of the cylinder block 1, a front surface 10b, a rear surface 10c, a case joining surface 8 and a cover. Each of the sliding cores 12a, 12b, 12c, 12d forming the joint surface 9 and the movable mold 13 forming the cylinder head joint surface 5 are combined to form the cavity of the cylinder block 1. I have.

[0008]

In casting, each mold 11, mold 13, and sliding cores 12a to 12d are used.
Are heated to an appropriate temperature, but since these dies have different volumes, the temperature is difficult to be uniform even when heated,
Even if the heating time is lengthened, complete temperature uniformity cannot be achieved.

As described above, if there is a temperature difference between the dies, the direction of shrinkage of the material is not uniform due to the difference in the solidification speed of the molten metal, and thermal stress distortion occurs during the shrinkage. In the case of (1), there is a problem that minute cracks due to shrinkage cracks are generated particularly at the edge of the cylinder head joint surface 5 and the case joint surface 8 which are end surfaces corresponding to the split surface of the mold.

In order to cope with this inconvenience, measures have been taken, for example, to cool the mold to be heated to a high temperature. However, in this case, another trouble is induced as the structure of the mold becomes complicated. At the same time, it is not possible to provide a complete solution because of the increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when casting and manufacturing a cylinder block using a combination of a plurality of dies, the cost is reduced.
It is an object of the present invention to provide a cylinder block casting method for preventing a crack which is likely to be generated at an edge of an end face corresponding to a split surface of a mold due to shrinkage cracking during solidification of a molten metal and obtaining a good quality cylinder block. .

[0012]

DISCLOSURE OF THE INVENTION The present invention has been made to achieve the above-mentioned object. In forming a cylinder block by casting, a cylinder block according to a split surface of a mold is provided.
The end face of the lock, which is joined to another workpiece after molding (example)
For example, the cylinder head joining surface 5, the case
A ridge having a predetermined height is formed on the outer edge of the end face to be the joining surface 8) at the time of casting the cylinder block .
It is characterized by processing smoothly the end face by cutting the ridge.

[0013]

According to the cylinder block casting method of the present invention, the end face of the cylinder block corresponding to the split surface of the mold is provided.
By forming a ridge having a predetermined height on the outer edge of the end surface which becomes a joining surface with another work after molding at the time of casting the cylinder block , the heating temperature of the mold is not uniform, and Even if the direction of shrinkage of the material is not uniform due to the difference in solidification rate, the thermal stress generated during shrinkage is dispersed in the ridge. As a result, the occurrence of fine cracks due to shrinkage cracks at the outer edge portion of the end surface is prevented. And this ridge is deleted by cutting, and it is set as a product.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method of the present invention will be described below with reference to the drawings.

In this embodiment, when the cylinder block 1 shown in FIG. 6 is formed by casting, in particular, ridges 21 and 22 are formed at the edges of the cylinder head joint surface 5 and the case joint surface 8, respectively. I do.

As shown in FIG. 3, the ridges 21 of the cylinder head joint surface 5 are formed on the outer walls 2B on the front surface 10b side and the rear surface 10c side of the cylinder block 1, respectively. The projecting ridges 22 of the case joining surface 3 are formed at left and right ends of the case joining surface 3.

As shown in FIGS. 4 and 5, in order to form the projections 21 and 22, the movable mold 13 and the sliding core 12c are formed with grooves 21 in which the projections 21 and 22 can be formed.
a and 22a are formed respectively. These grooves 21
movable mold 13 and sliding core 12 in which a and 22a are formed
c, the fixed mold 11, each sliding core 12a, 12b,
After the 12d and the movable mold 13 are combined and heated to an appropriate temperature as shown in FIGS. 4 and 5, the molten metal is put into the internal cavity under pressure and cast.

The above-mentioned ridges 21 and 22 are formed on the cylinder head joint surface 5 and the case joint surface 8 of the material of the cylinder block 1 formed by casting. By forming the protruding ridges 21 and 22 in this manner, each of the molds 11 and 13 and each of the sliding cores 12a to 1
Even if the heating temperature of 2d is not uniform, and the contraction direction of the material is not uniform due to the difference in the solidification rate of the molten metal,
As the ridges 21 and 22 are cast, the thermal stress generated at the time of shrinkage is distributed to the ridges 21 and 22. As a result, fine cracks, which are likely to occur due to shrinkage cracks, are prevented at the edges of the cylinder head joint surface 5 and the case joint surface 8.

Thereafter, when processing the material of the cylinder block 1 which has been cast and formed, the projections 21 and 22 are cut to smooth the cylinder head joint surface 5 and the case joint surface 8.

According to the cylinder block casting method of the present embodiment, fine cracks can be prevented from occurring on the cylinder head joint surface 5 and the case joint surface 8 as described above, and a good quality cylinder block can be obtained. Can be.

Further, in the present method, it is not necessary to cool the mold to be heated to a high temperature, and the grooves 21 for forming the protrusions 21 and 22 are simply formed in the sliding core 12c and the movable mold 13.
Since a and 22a may be formed, an increase in cost can be suppressed.

The height of each of the ridges 21 and 22 is set to a height at which thermal stress can be dispersed at the time of shrinkage due to solidification of the molten metal.

In the above embodiment, the ridges are formed on the cylinder head joint surface 5 and the case joint surface 8, but they may be formed as appropriate at locations where shrinkage cracks are likely to occur in accordance with the temperature difference of the mold. .

[0024]

As described in the foregoing, according to the casting method for processing a cylinder block of the present invention, upon forming the cylinder block by casting, silicon corresponding to the parting plane of the mold
Joining with other work after molding
The outer edge of the end surface to be plane, cylindrical and ridges of a predetermined height
Da block protruding form at the time of casting, after casting, characterized in that by cutting the ridge processing the end surface smooth, uniform shrinkage direction of the material due to the difference in the solidification rate of the molten metal Even if it does not occur, the thermal stress generated at the time of shrinkage is dispersed in the ridge, so that there is an effect that minute cracks due to shrinkage cracks, which are easily generated at the edge of the end face, are prevented.

[Brief description of the drawings]

FIG. 1 is a side view of a cylinder block obtained by a method according to an embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a sectional view taken along line DD in FIG. 2;

FIG. 4 is a side view showing a mold, a core, and the like.

FIG. 5 is a plan view of the same.

FIG. 6 is a perspective view of a general cylinder block formed by casting.

FIG. 7 is a sectional view taken along line EE of FIG. 6;

FIG. 8 is a side view for explaining a mold used in a conventional method.

FIG. 9 is a plan view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 5 Cylinder head joint surface 8 Case joint surface 11 Fixed mold 12a, 12b, 12c, 12d Sliding core 13 Movable mold 21, 22 Ridge

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 17/00 B22D 17/22 B22D 31/00 F02F 1/00

Claims (1)

(57) [Claims] 1. An end face of a cylinder block corresponding to a split surface of a mold in forming a cylinder block by casting.
A ridge having a predetermined height is formed at the outer edge of the end surface which becomes a joining surface with another workpiece after molding, at the time of cylinder block casting, and after casting, the ridge is cut. A method of casting a cylinder block, wherein the end face is processed smoothly.