JPH11226716A - Casting mold - Google Patents

Abstract

(57) [Summary] [Problem] An intended temperature distribution can be easily obtained without excessive cooling or heating of a main die (die main body) by an insert die, and the orientation of molten metal can be obtained. Provided is a casting mold capable of performing active solidification and preventing casting defects such as shrinkage cavities and poor run-off. A plurality of grooves (5b, 5c, 5d) are formed on a contact surface between a main die (4) and an insert die (5) in parallel and at equal intervals to transfer heat between the main die (4) and the insert die (5). Suppress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting mold used as a mold for casting various parts, and more particularly, to an insert mold in a mold, which is used to locally cool or melt molten metal in a cavity. The present invention relates to a casting mold capable of achieving directional solidification of a molten metal by heating.

[0002]

In the case of casting a component having a complicated shape in which a thick portion and a thin portion coexist, it is necessary to prevent the occurrence of defects such as shrinkage cavities and poor running of the melt. An insert mold having a cooling or heating (warming) jacket is partially inserted to locally cool or heat the molten metal in the cavity to obtain a temperature distribution for directional solidification of the molten metal. . However, the temperature of the main mold may decrease or increase due to heat transfer between the insert mold and the main mold. In such a case, there is a problem that a target temperature distribution cannot be obtained.

For example, when casting an aluminum road wheel for automobiles by low-pressure casting, shrinkage cavities are apt to be formed in a thick portion from a spoke to a rim, so that water cooling is performed at a position facing the thick portion of the cavity. By disposing an insert mold having a jacket, the solidification of the molten metal in the thick portion is promoted, and the occurrence of shrinkage cavities is prevented. However, in this case, not only the insert mold but also the main mold part is cooled by water-cooling the insert mold, so that the temperature of the entire mold is reduced, and the thinner inner rim portion farthest from the gate is filled with hot water. A rotation defect may occur.

In general, a copper-based alloy having excellent thermal conductivity is often used as an insert-type material, and its mechanical performance is inferior to that of a main-type material (eg, alloy tool steel SKD). In addition, since it is often applied to parts with disadvantageous strength such as pins, for example, the service life is shorter than that of the main mold and it is easy to be damaged. The problem is that there is no danger of casting defects and steam explosion due to infiltration into the steel, and solving these problems has been an issue for casting technology using molds with insert molds. .

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional die casting, and the die main body (main die) is excessively cooled or heated by the insert die. It is an object of the present invention to provide a casting mold capable of easily obtaining a target temperature distribution without any defects, and obtaining a cast component having a desired quality without casting defects. Another object of the present invention is to provide a casting mold that can safely discharge water or steam in a jacket without flowing into a cavity even if an insert mold is damaged.

[0006]

According to a first aspect of the present invention, there is provided a casting mold having an insert mold, wherein a groove is formed in a contact surface between the main mold and the insert mold. It is characterized in that it has a certain configuration, and the configuration of such a casting mold is a means for solving the above-mentioned conventional problems.

In a casting mold according to a second aspect of the present invention, a plurality of grooves are formed on the contact surface between the main mold and the insert mold at equal intervals. According to a third aspect of the present invention, there is provided a casting mold according to the third aspect, wherein the groove is open to the side opposite to the cavity.

[0008]

In the casting mold according to the first aspect of the present invention, since a groove is formed in the contact surface between the main die and the insert die, the contact area between the two is reduced. Since heat transfer between the main mold and insert mold is suppressed, and the temperature change of the main mold is minimized, it is possible to easily obtain the intended temperature distribution, such as shrinkage cavities and poor running water. An extremely excellent effect that a high quality cast part free of casting defects can be easily obtained.

In a casting mold according to a second aspect of the present invention, a plurality of grooves are formed on the contact surface between the main die and the insert die, and these grooves are parallel to each other and at equal intervals. Since they are juxtaposed, the force exerted on the contact surface of the insert mold due to thermal expansion or molten metal pressure during casting can be averaged, and damage due to local concentration can be prevented. In the casting mold, since the groove is open on the opposite side of the cavity, even if the insert mold is damaged and water or water vapor in the jacket leaks, the groove on the opposite side of the cavity is opened through the opening of the groove. The pressure can be released to the inside of the cavity, and a more excellent effect that the risk of casting defects due to the inflow into the cavity and the danger of steam explosion can be avoided can be brought about.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a mold used for low-pressure casting of an aluminum road wheel as one embodiment of a casting mold according to the present invention.

The casting mold 1 shown in FIG. 1 has a main mold divided into four parts, that is, an upper mold 2, a lower mold 3, and left and right dies 4, 4, and insert dies 5, 5 disposed on the left and right dies 4, 4. 5, a cavity 6 is formed between them, and the molten metal flows into the cavity 6 from the gate 7.

That is, in the casting mold 1,
The portion from the spoke portion 6a to the rim portion 6b of the road wheel obtained by the cavity 6 is thick, and from the viewpoint of preventing shrinkage cavities that are likely to occur in this portion, the thick portions of the left and right dies 4, 4 The insert dies 5 and 5 made of a copper alloy having excellent thermal conductivity and provided with a water cooling jacket 5a are provided at desired locations. The upper mold 2, the lower mold 3, the left and right molds 4, 4 which are the main molds are JIS G440.
4 SKD61 (Cr-Mo alloy tool steel)
-V steel).

The insert dies 5 and 5 are further provided with a plurality of grooves 5 in contact surfaces with the main dies, in this embodiment, the left and right dies 4 and 4.
b, 5c.

That is, as shown in an enlarged view of FIG. 2A, the width w =
10 mm, depth d = 2 mm, bottom radius of curvature r = 2 mm
21 grooves 5b (see FIG. 3) are formed parallel to each other at a pitch of p = 20 mm. These grooves 5b are formed by insert dies 5 curved along the outer peripheral surface of the left and right dies 4 having a cylindrical shape.
The grooves 5c are formed in the vertical plane of the mold 1 and open upward through the grooves 5c in FIG.

Further, the bottom surface of the insert mold 5 is shown in FIG.
(B) As shown enlarged, 21 grooves 5 of the same size
d are formed in parallel with each other at the same pitch, and these grooves 5d are opened to the outside of the mold 1, that is, on the side opposite to the cavity via the step 5e.

Therefore, even if the insert mold 5 is damaged and water or water vapor leaks from the crack, the grooves 5b, 5
Since the gas is discharged from c and 5d to the side opposite to the cavity through the opening, contact with the molten metal can be avoided, and accidents such as steam explosion can be prevented.

As for the grooves 5b to 5d, it is desirable to form grooves having a relatively narrow width at a relatively fine pitch as in this embodiment from the viewpoint of the service life of the insert die 5. That is, the heat transfer between the insert mold and the main mold is averaged in the width direction, the temperature gradient becomes gentle, and the force due to the thermal expansion and the pressure of the molten metal is dispersed,
Since there is no need to concentrate on a part, breakage of the insert mold can be effectively prevented.

In this embodiment, an example is shown in which the groove is formed on the side of the insert mold. However, depending on the size, shape, and arrangement position of the insert mold, the side of the main mold or the main mold and the insert mold may be used. May be provided with grooves.

The insert dies 5 and 5 having such a shape are as follows.
Four bolts (not shown) inserted from the lower sides of the left and right dies 4, 4 are fixed to the main dies by being screwed into screw holes 5f to form the insert dies 5, 5, respectively. The female screw hole 5f is formed at a central position between the grooves so that the groove 5d is not closed by the bolt.

Next, the casting mold 1 having the above structure was mounted on a low-pressure casting machine, and an aluminum road wheel was actually cast. A conventional mold having no groove formed in the insert mold was used. A comparison was made between the case and the occurrence of defects.

As a result, when a conventional mold having no groove formed in the insert mold is used, shrinkage cavities in a thick portion can be prevented, but the mold is furthest from the gate 7,
In addition, the casting dies 1 having the above-described structure have the advantage that the inner rim portion having a thin wall shape has poor running water.
When no. Was used, not only the shrinkage cavities of the thick wall portion but also the inner rim portion 6c did not suffer from runoff, and it was confirmed that a cast product of good quality was obtained.

Table 1 shows the surface temperature of the die 1 measured at this time for the insert die 5 and its peripheral portion (see FIG. 4), and compared with the case of the conventional die having no groove in the insert die. It shows the results obtained.

[0024]

[Table 1]

As is apparent from the results, in the conventional mold having no groove in the insert mold, the main mold portion is also cooled by water cooling of the insert mold, whereas the casting mold according to the present invention is cooled. In the mold 1, the grooves 5b to 5d are provided on the contact surface of the insert mold 5 with the left and right molds 4, so that the water cooling effect does not reach the left and right molds 4, and only necessary portions are locally and efficiently cooled. It was confirmed that an ideal temperature distribution enabling directional solidification of the molten metal could be obtained.

In this embodiment, an example in which shrinkage cavities are prevented by cooling the insert mold is shown. However, even when the molten metal is locally heated by passing a heated fluid, for example, steam, through the jacket, It goes without saying that the groove structure according to the present invention can be applied.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing the structure of a casting mold according to one embodiment of the present invention.

FIG. 2A is an enlarged explanatory view showing an upper surface of an insert mold in the casting mold shown in FIG. 1; (B) It is an expansion explanatory view similarly showing the bottom face of an insert type.

FIG. 3 is an explanatory sectional view showing a shape of a groove formed in an insert mold.

FIG. 4 is an enlarged explanatory view showing measurement points of a temperature distribution in the casting mold shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 casting mold 2 upper mold (main mold) 3 lower mold (main mold) 4 left-right mold (main mold) 5 insert mold 5b, 5c, 5d groove

Claims (3)

[Claims] 1. A casting mold provided with an insert mold, wherein a groove is formed on a contact surface between the main mold and the insert mold. 2. The casting mold according to claim 1, wherein a plurality of grooves are formed on the contact surface between the main mold and the insert mold at equal intervals. 3. The casting mold according to claim 1, wherein the groove is opened on the side opposite to the cavity.