JPS595381B2 - Mold manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a mold with good roasting resistance.

When casting a material with a high melting temperature, such as steel, the mold seizes frequently during casting, and this tendency is particularly noticeable in areas such as the front of a weir where molten steel hits at high speed.

When seizing occurs, the casting surface becomes rough and the quality of the cast product is significantly impaired.

As a method of preventing such burning, there is a method of applying a refractory coating material to the surface of the mold, but since the foundry sand itself has insufficient fire resistance, it is difficult to obtain satisfactory roasting resistance.

On the other hand, zircon sand (ZrO2.5102) and chromite sand (Or203.MgO-Al2O3.Fe0)
When using roasting-resistant sand such as, the roasting-proofing property becomes good, but there are drawbacks as shown below.

That is, since the above-mentioned roasting-resistant sand is more expensive than ordinary foundry sand, if the entire foundry sand is replaced with roasting-resistant sand, the material cost will rise.

Therefore, a method is usually adopted in which the surface of the wooden mold is filled with dawn-resistant sand and then filled with backing sand, but even then, a large amount of roasting-resistant sand must be used, and the molding process is difficult. is complicated and time-consuming.

The inventors of the heather focused on the above-mentioned circumstances and conducted research with the aim of establishing a technology that would reduce the amount of expensive roasting-resistant sand used and improve roasting resistance with simple molding operations. We have been progressing.

The present invention was completed as a result of such research, and its configuration is that when manufacturing a mold by applying molding sand to a wooden mold, a sub-mold is attached to a part of the surface of the main mold so as to protrude. The gist is that after filling with molding sand, and after the molding sand has hardened, the sub mold is removed from the surface of the main mold, and after the sub mold is removed, roasting-resistant sand is applied to the recesses on the mold surface to shape the surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration and effects of the present invention will be described below based on drawings showing embodiments.

FIGS. 1A to 1D are schematic cross-sectional explanatory views illustrating the manufacturing method of the present invention, in which a sub-mold 2 is protruded and attached to a proper position on the surface of a main mold 10 (a surface corresponding to the part of the mold most likely to cause seizing). [Figure 1A].

This is placed in a mold 3, and ordinary molding sand 4 is piled up on the surface of the wooden mold, and the outer periphery thereof is filled with backing sand 5, and the molding sands 4 and 5 are hardened (FIG. 1 β).

Next, the main mold 1 and the sub-mold 2 are removed [Fig. 1C], and the mold surface concavities 6 after the sub-mold 2 has been removed are coated with roasting-resistant sand 7 such as zircon sand or chromite sand to shape the surface. In this way, a mold with good roasting resistance can be obtained (Fig. 1D).

In this way, in the present invention, by setting the mounting position on the main mold, the coating position of the roasting-resistant sand can be freely changed, and the parts where roasting-resistant sand is most needed can be intensively reinforced.

In addition, for a part where almost no burning occurs, the sub-mold 2 is not attached to the corresponding surface of the main mold 1, and the molding can be performed so that normal skin sand is exposed.

Furthermore, even in areas where burning occurs, the degree of burning varies considerably depending on the location, but with the present invention, the coating thickness of the roasting-resistant sand 7 can be freely adjusted by changing the thickness of the sub-mold 2. The coating thickness can be changed according to the required degree of roasting resistance, and a mold with excellent roasting resistance can be obtained with a minimum amount of roasting resistant sand.

In any case, if you use roasting-resistant sand like the one mentioned above, it will be 5 to 2
Sufficient roasting resistance can be obtained with a coating thickness of about zero.

The material of the sub-mold is not particularly limited, but wood and synthetic resin are the most common in terms of price and ease of handling.
Among them, foamed resins such as foamed sterol are prized as the most suitable materials because they are lightweight and easy to process.

Furthermore, the means for attaching the sub mold to the main mold is not particularly limited, and any method such as joining with adhesive or fixing by driving with nails or the like can be employed.

However, the attachment of subtype 2 is only temporary,
Particularly when the sub-mold becomes undercut during demolding, it is advantageous for it to be easily removed from the main mold, so it is advantageous to use a relatively weak starch-based adhesive or the like to join the sub-mold.

FIG. 2 is a cross-sectional view of a main part showing another embodiment of the present invention, in which a sub mold 2 having nails 8 protruding outwardly is attached to the main mold 1.

If this method is adopted, a mark 61 of the nail 8 will be left in the recess 6 after removing the sub-mold 2 [Fig. 2B], and this part will be filled with roasting-resistant sand and will become a root. The adhesion of the sand layer can be improved.

For the same purpose, it is advantageous to form irregularities on the outer surface of the sub-mold 2 as shown in FIGS. 3A and 3B, since the bonding area between the casting sand layer and the roasting-resistant sand layer is expanded and the adhesion is improved.

Furthermore, when the 60 layer is thick, nails 8 or the like can be driven into the molding sand 4 to prevent the roasting-resistant sand layer from deforming.

[Figure 3C].

FIGS. 4A to 4C are sectional views of main parts showing still another example of the present invention, which is an example in which the amount of molding sand 4 used can be reduced.

That is, in this example, the molding sand 4 is applied only to the exposed part of the main mold 1, and the backing sand 5 is directly filled to the part to which the sub-mold 2 is attached (FIG. 4A).

After removing the main mold 1 and the sub-mold 2, the recess 6 is filled with roasting-resistant sand 7 and the surface is shaped to produce a roasting-resistant mold.

If this method is used as a tangent, the foundry sand used as skin sand 4
The usage amount can also be reduced, further reducing material costs.

The present invention is roughly configured as described above, and it is possible to easily form a localized layer of roasting-resistant sand only in the parts of the mold that are prone to burning, and a small amount of roasting-resistant sand is sufficient to provide sufficient roasting-resistant sand. It became possible to add performance.

In addition, the formation range and location of the roasting-resistant sand layer can be freely changed by changing the size and mounting position of the sub-mold, and can be applied to molds of any shape that require roasting-resistant sand. This is an extremely excellent molding method.

[Brief explanation of drawings]

FIG. 1 is a process explanatory diagram illustrating the manufacturing method of the present invention, and FIG.
FIG. 4 is a cross-sectional view of main parts showing another actual case. 1...Main mold, 2...Sub-mold, 3...Formwork, 4...
Foundry sand, 5... Back sand, 6... Concavity, 7... Roasting resistant sand.

Claims (1)

[Claims] 1 In a mold manufacturing method using a wooden mold and foundry sand, a sub-mold is attached to a part of the surface of the main mold so as to protrude, and after the molding sand has hardened, the main mold and sub-mold are removed, and the mold surface after the sub-mold is removed. A mold manufacturing method characterized by applying roasting-resistant sand to the recesses and shaping the surface.