JPH03169454A - Method for casting light alloy-made cylinder block - Google Patents

Abstract

PURPOSE:To restrain deformation of a cylinder liner with a holding part, to execute cooling for a short time and to improve working efficiency by cooling a casting with the holding part of a base die remained in the cylinder liner. CONSTITUTION:A supporting water head 21 is inserted into dies opened and cooling water mixing air is sprayed from the nozzles 22, 22... thereof to the casting 6 head in the first die 1 side and the casting 6 is quickly and forcedly cooled to the prescribed temp. By the forced cooling with such a cooling water, the casting 6 is quickly cooled and shrunk, but as the cylinder liner 15 is supported with the holding part 14 from the inside thereof, it is scarcely deformed and the circularity thereof is maintained even if the liner is subjected to shrinking force. After lowering to the prescribed temp., the casting 6 is separated from the first die 1 to complete the casting of cylinder block.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for casting a light alloy cylinder block.

(Prior art) In recent years, in automobile engines, due to the demand for lighter engines, it has become common to cast cylinder blocks from light alloys, such as aluminum alloys. In order to improve the abrasion resistance of the moving body, a cast iron cylinder liner is cast inside.

However, when a cast iron cylinder liner is cast into a light alloy cylinder block as described above, there is a problem in that the cylinder liner is deformed mainly due to cooling shrinkage of the cast product after solidification of the molten metal. The deformed state of the cylinder liner is shown in an exaggerated manner in FIG.
2. ..., the deformation of the Norinda liner 52 divided into the cylinders in the center in the cylinder arrangement direction is the largest.

Such deformation of the cylinder liner is caused, for example, when the inner surface of the cylinder liner is ground after casting, the grinding depth differs depending on the amount of deformation, resulting in uneven thickness of the cylinder liner, which causes the cylinder liner sliding surface to become uneven during engine operation. It is necessary to prevent this as much as possible since it may cause problems such as not being able to ensure roundness.

From this point of view, for example, Japanese Patent Application Laid-Open No. 62-81248
The publication proposes a technique in which a diameter expanding force is applied to the cylinder liner and the temperature of the cylinder liner is maintained until it reaches room temperature, thereby making the amount of thermal expansion approximately uniform around the circumference of the cylinder liner.

(Problem to be Solved by the Invention) However, in this prior art, after casting, the cast product is left to cool while being held in the mold, so even if cooling water is not in the mold, Even if there is a cooling means such as (
(not disclosed in the above-mentioned known examples), since the cast product is cooled through a mold, it takes a long time to cool the cast product, and as a result, the working time in the casting process becomes longer. , a problem arises in that work efficiency decreases.

Further, in this prior art, since a dedicated diameter expanding device is disposed within the cylinder liner, there is also a problem that the structure of the mold becomes complicated and costs increase.

Therefore, the present invention aims to cast a cylinder block made of light alloy, which has a simpler and cheaper structure to prevent deformation of the cylinder liner due to cooling shrinkage of the cast product, and improves workability in the casting process. This was done for the purpose of proposing a method.

(Means for Solving the Problem) In the present invention, as a specific means for solving the problem, a holding part that holds the cylinder liner in a substantially contacting state from the inner surface thereof and a holding part that is arranged so as to surround the cylinder liner are provided. A plurality of base molds corresponding to the top deformation side of the cylinder block having a jacket core and a core molded therein, and a plurality of molds arranged so as to be able to abut against and be separated from the heath mold, and forming a cavity for forming the cylinder block therebetween. In a casting device equipped with a sub-mold, when opening the mold after pouring metal into the cavity, first separate each sub-mold from the cast product while leaving the base mold on the cast product side. After molding, the upper cast product held on the base mold side is forcibly cooled by forced cooling means, and when the temperature of the cast product has decreased to a predetermined temperature, the Heas mold is removed from the cast product. It is characterized by being able to be released from the mold.

(Function) Since the present invention has such a configuration, (1) the casting is cooled with the base mold holding part left in the nolinda liner, so that the deformation of the nolinda liner due to cooling shrinkage of the casting is caused by the holding part; (2) The cooling of the casting is forcibly completed in a short time by the forced cooling means.

(Effects of the Invention) Therefore, according to the method for casting a light alloy cylinder block of the present invention, ■ The deformation of the cylinder liner is suppressed by the base mold itself, and no special equipment is required; The following effects can be obtained: 1) The structure of the cast product can be simplified and costs can be reduced; 1) Since the casting product can be cooled in a short time, the work tact in the casting process can be shortened and work efficiency can be improved.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 and 2 show a casting apparatus Z used for carrying out a casting method according to an embodiment of the present invention. This casting device Z is for casting a cylinder block for a V-type 6-cylinder made of aluminum alloy, and includes a first mold l disposed on a movable block 30 and forming the top facing side of the cylinder block; A second mold 2 is arranged on the fixed block 31 so as to be able to abut and separate relative to the first mold l, and forms the bottom deck side of the cylinder block; It has a third mold 3 and a fourth mold 4, which are arranged so as to be able to abut and separate from above and below, and which are formed on the sides of the cylinder block. (Illustration of type is omitted). That is, in this embodiment, the first mold 1 corresponds to the base mold in the claims, and the other molds 2
, 3.4 respectively correspond to the sub molds.

A cavity 5 is formed inside each of these molds 1 to 4. In addition, each of these molds 2 to 4 on the moving side
The direction of movement is as indicated by arrows A-F in FIGS.

The first mold l is a mold body I that forms the inter-bank portion.
I and a pair of left and right bore forming portions 1 2 . 1 2 forming the cylinder bore side of each bank.

The bore forming portion I2 is movable in the cylinder bore axial direction (arrow G-H direction) with respect to the mold body II. Further, at the tip of this bore formation 112, there is a rod-shaped retainer 14 that fits and holds the cylinder liner 15 in a substantially intimate state, and a jacket core l3 disposed so as to surround the outside of the retainer l4. are provided for each. The cylinder liner l5 is fitted and held in advance in this holding part I4 during mold matching, but when the cylinder liner 15 is fitted into this holding part 14, as shown in FIGS. 1 and 2, , the top portion 14a of the holding portion l4 protrudes forward by an appropriate dimension from the upper end surface of the cylinder liner 15 (see the portion 14a' shown by the chain line in FIG. 3).
The length of the holding portion 14 is set relative to the cylinder liner 15 so that

When casting a 7-ring block using the casting apparatus Z configured as described above, first, as shown in FIG. In a state where they are fitted and held, the second to fourth molds 2 to 4 are brought into contact with the first mold l to form a cavity 5 therebetween. Then, molten aluminum alloy is injected into the cavity 5 in this lowered state.

After this molten metal solidifies in the cavity 5 and a cast product 6 is formed therein, the mold is opened. In this case, as shown in FIG. On the other hand, the movable block 3o having the first mold I, the third mold 3, and the fourth mold 4 is opened, and then the third mold is used for the first mold l on the movable block 3o side. The mold 3 and the fourth mold 4 are each opened to release them from the cast product 6. At the same time, on the first mold l side, as shown in FIG. The upper end 15a is moved back slightly to the extent that it is almost flush with the upper end 15a.
' to the position l4 shown by the solid line).

Therefore, in this state, the inner surface of the cylinder liner l5 cast in the aluminum alloy motherboard is backed up by the holding part 14, and the jacket core 13
On the side, since this has a predetermined draft angle, a minute gap is created between the surface of the jacket core 13 and the inner surface of the water jacket 61 formed thereby. In this way, the reason why the bore forming part l2 is slightly retreated after the molten metal solidifies to form a gap between the jacket core I3 and the water jacket 61 is because the tip of the jacket core I3 is draft inclined. Its thickness is very thin, so the jacket core l3
If it is left in the state it was in when poured, there is a risk that the tip of the guy will seize or melt due to the heat of the high-temperature casting 6. To prevent this, the above-mentioned gap is provided. It is. In this case, since the holding portion l4 is formed into a rod shape with almost no draft, the backup state of the cylinder liner 15 is maintained.

After that, in this state, the water supply head 2l is inserted into the opened mold as shown in FIG.
2,22. Cooling water mixed with air is sprayed from ... onto the cast product 6 that is still held on the first mold l side, and the cast product 6 is quickly and forcibly cooled to a predetermined temperature (
In this embodiment, this water supply head 2 constitutes forced cooling means in the claims.

Due to this forced cooling by the cooling water, the cast product 6 cools and contracts at a negative speed, and this shrinkage force is applied to the outer circumferential side of the cylinder liner l5, but since the cylinder liner l5 is backed up from the inside by the retainer 14, It maintains its roundness with almost no deformation even when subjected to contractile force (realization of the deformation suppressing effect of the cylinder liner).

This holding of the cast product 6 on the first mold 1 side is continued until the temperature of the cast product 6 reaches a predetermined temperature (continued). After the temperature has decreased to a predetermined temperature, the cast product 6 is released from the first mold 1. This completes the casting of the cylinder block.

Here, the above-mentioned predetermined temperature is a temperature at which cooling shrinkage of the cast product 6 does not significantly affect the deformation of the cylinder liner 15, and in this embodiment, it is approximately 270°C.
It is set to about. The basis for setting this temperature is as follows.

That is, the inventors of the present invention confirmed through experiments the correlation between the temperature when the cast product 6 was taken out from the mold and the amount of deformation of the cylinder liner 15 in that case, and the results are shown in FIG. It was on the street.

As can be seen from this experimental result, when the temperature at which the cast product 6 is taken out is higher than about 270°C, the cylinder liner I
The amount of deformation of No. 5 suddenly increases, but at temperatures below 270°C, the amount of deformation is relatively small, 300 μ or less. At this level, if the inner surface of the cylinder liner No. 7 is ground after casting, there will be no large deviation in the cylinder liner. There seems to be no problem in practical use as no meat is produced. Considering the reason from the perspective of the amount of deformation of the cylinder liner and the reason from the perspective of improving work efficiency by shortening the takt time of casting work, in this example, the above predetermined temperature was set to about 270°C. This is what I set it to.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the main parts of the casting equipment used to carry out the casting method of the present invention, Fig. 2 is a state change diagram of the casting equipment shown in Fig. 1, and Fig. 3 is a diagram of the casting equipment shown in Fig. 2. FIG. 4 is a partially enlarged view, and FIG. 4 is a correlation diagram between the temperature and amount of deformation of the cast product, and FIG. 5 is an explanatory diagram showing an exaggerated state of deformation of the cylinder liner. l...Lth mold (base mold) 2...Second mold (sub mold) 3...Third mold (sub mold) 4...Fourth mold (sub mold) Mold) 5... Cavity 6... Casting product 11... Mold body! 2...Bore forming part 13...Jacket core 14...Holding part l5...Cylinder liner 2l...Water supply head 22...Nozzle 1 Figure 1...First mold (base mold) 2...・Second mold (sub mold) 3...Third mold (sub mold) 4...Fourth mold (sub mold) 5...Cavity 6...Cast product 11... Mold body l2...Bore forming hole 13...Jacket core I4...Holding part 15...Cylinder liner 21...Water supply head 22...Nozzle Fig. 4 Fig. 5

Claims (1)

[Claims] 1. A base mold corresponding to the top deck side of the cylinder block, which is equipped with a holding part that holds the cylinder liner in almost contact with the cylinder liner from its inner surface, and a jacket core arranged to surround the cylinder liner. In a casting apparatus equipped with a plurality of sub-molds that are arranged so as to be able to collide with and be separated from the base mold and constitute a cavity for forming a cylinder block between them, the mold after pouring into the cavity. When opening, first, each of the sub molds is released from the cast product while leaving the base mold on the cast product side, and then
The cast product held on the base mold side is forcibly cooled by forced cooling means, and when the temperature of the cast product has decreased to a predetermined temperature, the base mold is released from the cast product. A method for casting a light alloy cylinder block, characterized by: