JP2000190065A - Casting method and casting seal material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of flash at a high working efficiency without causing a shape failure to a casting product. SOLUTION: Graphite sheets 7 are arranged near an inside end of a mold engaging part between sand molds 4a and 4b. Since the graphite sheets have flexibility and are arranged between the sand molds 4a, 4b without a gap, the molten material rarely flows between them. Also, the graphite sheets do not go inside the mold in disorderly, because they are nipped between the sand molds 4a and 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method and a sealing material for casting, and is suitably used for preventing occurrence of casting.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 51-19807 discloses a method of mixing an oily substance, an emulsified oil, a binder and a refractory, which is used to prevent casting during metal casting. A sealing material is disclosed. This sealing material
During casting, it is extruded into a cylindrical shape from a nozzle and arranged between the upper and lower molds, and is sandwiched between the upper and lower molds so as to be in close contact with them and prevent casting, hot water leakage and the like.

[0003]

However, since the sealing material described in the above-mentioned publication is paste-like, it is deformed into a thin film by being sandwiched between upper and lower molds, and is randomly distributed from the mold matching portion to the inside of the mold. It may protrude. As described above, when the sealing material randomly protrudes from the mold matching portion to the inside of the mold, a defective shape of the cast product occurs. Further, the sealing material described in the above-mentioned publication is difficult to handle because it is in a paste form, and is not preferable in terms of working efficiency.

[0004] Therefore, an object of the present invention is to provide a casting method and a casting method capable of easily preventing casting without causing a defective shape of a cast product due to irregular protrusion of a sealing material from a mold matching portion to the inside of a mold. An object of the present invention is to provide a casting sealing material to be used.

[0005]

According to a first aspect of the present invention, there is provided a casting method using a combination of a plurality of molds so that molten material does not flow between adjacent molds. The method is characterized in that the molten material is introduced into the mold in a state where the graphite sheet is arranged near the end of the mold matching portion on the side in contact with the molten material. That is, the present inventors have conducted various experiments while repeating trial and error in search of a material that solves the above problem,
In connection with the casting method using a combination of a plurality of molds, it has been found that a graphite sheet is most suitable as a material used for preventing the occurrence of casting. In the casting method according to claim 1, the graphite sheet is arranged so as to cover the mold matching portion over the adjacent molds, and the graphite sheet is arranged between the adjacent molds near the end. It encompasses both cases.

The graphite sheet used in the first aspect is a flexible graphite sheet obtained by subjecting natural graphite or the like to a chemical treatment and then heating and expanding the resultant into a sheet shape. Therefore, according to the first aspect, the flexible or flexible graphite sheet is provided on the side where the molten material is brought into contact with the mold of the adjacent mold so that the molten material does not flow between the adjacent molds. Is arranged by being stuck or interposed without any gap near the end of the mold, and substantially no casting occurs due to the flow of the molten material from the vicinity of the end to the space between the adjacent molds. Even if casting is caused by the casting method of claim 1, since the graphite sheet is used, the casting is smaller and thinner than usual. Processing becomes easier.

Further, the graphite sheet used in the first aspect has excellent heat resistance, so that even if a high-temperature molten material is used, the graphite sheet hardly deteriorates. In addition, the graphite sheet used in claim 1 has a smaller degree of deformation when pressed as compared with the pasty sealing material described in the above-mentioned publication, so that the graphite sheet may protrude randomly between adjacent molds. Absent. Therefore, according to the first aspect, substantially no defective shape of the cast product caused by the irregular protrusion of the graphite sheet from between the adjacent molds. Further, the graphite sheet used in claim 1 is superior in that it is easier to handle and improves work efficiency as compared with the pasty sealing material described in the above-mentioned publication.

[0008] The casting method according to claim 2 is characterized in that the graphite sheet is arranged so as to cover the mold matching portion across the adjacent molds at the end. In other words, the casting method according to claim 2 is such that the graphite sheet covers the mold matching part in claim 1, particularly at the inner end of the mold matching part of the main mold or the outer end of the mold matching part of the core. Is attached to the adjacent mold via an adhesive or the like, for example.

According to the second aspect of the present invention, the graphite sheet may be disposed in the mold matching portion after the combination of the molds, so that the work is performed in comparison with the case where the graphite sheet is arranged between the adjacent molds and then combined. Is easy. Further, since the graphite sheet is arranged so as to cover the mold matching portion, compared to the case where the graphite sheet is arranged between adjacent molds, the flow of the molten material between the molds is more effectively prevented. be able to. Therefore, it is possible to further suppress the occurrence of casting.

In a third aspect of the present invention, the graphite sheet is disposed between the molds near the end. In other words, the casting method according to claim 3 is the method according to claim 1, wherein the graphite sheet is adjacent to the mold near the inner end of the mold matching portion of the main mold or the outer end of the mold matching portion of the core. It is mentioned that it is arranged interposed. At this time, in order to increase the degree of adhesion between the graphite sheet and the mold, it is preferable to provide an adhesive layer on both sides of the graphite sheet and bond the graphite sheet and the mold with this adhesive layer, but without providing an adhesive layer. The effect of the present invention can be obtained only by arranging the graphite sheet between the molds.

According to the third aspect, since the graphite sheet is arranged between the adjacent molds, a concave portion corresponding to the thickness of the graphite sheet is not formed on the surface of the casting as in the second aspect.
In other words, in the second aspect, the graphite sheet disposed so as to cover the matching portion comes into contact with the molten material introduced into the mold, so that a concave portion corresponding to the thickness of the graphite sheet is formed on the surface of the casting. It is formed. In particular, when a graphite sheet is used for the main mold, a concave portion is formed on the front side of the cast product, which is not preferable. According to the third aspect, since the graphite sheet is disposed between the adjacent molds, the contact area between the molten material introduced into the mold and the graphite sheet is relatively small. The concave portion is not formed with a relatively large area. Therefore, the casting method of claim 3 is suitable for mainly applying to the main mold.

In the casting method according to the third aspect, it is not preferable that the end of the graphite sheet disposed between the molds protrudes or retracts from the end face of the mold, and the end of the graphite sheet is formed by the mold. Is preferably located on the same plane as the end face of the first. Because, in this way, it is possible to reliably suppress the occurrence of casting,
This is because no concave portion is formed on the surface of the casting.

In the casting method according to claims 1 to 3,
The graphite content of the graphite sheet is preferably 1000 ppm or less, more preferably 700 ppm or less.

The sulfur content of the graphite sheet is 1000 ppm
When the content is below, it is possible to considerably suppress a cast product such as ductile iron from being adversely affected by sulfur in the graphite sheet. Graphite sheet is usually 800-100
Although a sulfur content of 0 ppm is contained, a graphite sheet having a sulfur content lower than usual can be used by reducing sulfur by a suitable means in a graphite sheet manufacturing process. Further, the sulfur content in the graphite sheet is more preferably 700 ppm or less from the viewpoint of further reducing the adverse effect on the cast product.

[0015] In a fourth aspect of the present invention, the casting seal material is characterized in that an adhesive layer covered with a peelable member is attached to a graphite sheet. It should be noted that, in claim 4, the phrase "the adhesive layer is attached to the graphite sheet" means not only that the adhesive layer is directly attached to the graphite sheet, but also that another member is interposed between the adhesive layer and the graphite sheet. This includes the case where the adhesive layer is indirectly attached to the graphite sheet.

According to a fourth aspect of the present invention, in the casting method of the second aspect, an adhesive layer covered with a peelable member is attached to a graphite sheet. It can be used so as to cover the mold-fitting portion, and the efficiency of attaching the graphite sheet can be improved. Also, in a foundry where a lot of dust and the like are floating, if the adhesive layer is exposed for a long time, dust and the like adhere to the adhesive layer and it becomes difficult to attach the graphite sheet to the casting. In the casting seal material of No. 4, since the adhesive layer is covered with a peelable member, it is possible to prevent dust from adhering to the adhesive layer and prevent the graphite sheet from falling off from the casting.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

First, a casting method according to an embodiment of the present invention will be described with reference to an example of a method for casting a flanged pipe 1 as shown in FIG. In order to cast a flanged pipe 1 as shown in FIG. 1, a wooden main mold 2 as shown in FIG. 2A and a wooden core mold 3 as shown in FIG. I do.

Next, the wooden main mold 2 shown in FIG. 2A is embedded in sand to form upper and lower sand molds 4a and 4b as the main mold as shown in FIG. 3A. At both ends of the upper and lower sand molds 4a and 4b, metal frames 5a and 5b are provided, respectively. Also, upper and lower cores 6a and 6b made of sand having a semi-cylindrical shape are formed from the wooden core mold 3 of FIG. 2B.

Next, as shown in FIGS. 4A and 4B,
A graphite sheet 7 having a width of about 10 mm and a thickness of about 0.4 mm is provided between the upper and lower sand molds 4a and 4b and near the inner end (that is, the side that comes into contact with the molten metal) of these sand molds. Intervene. Also, as shown in FIG.
a, width of several tens of meters covering the matching part over a and 6b
The graphite sheet 8 having a thickness of about 0.4 mm and a thickness of about
6b. The graphite sheet 8 is adhered before the glaze is applied to the cores 6a and 6b to prevent the graphite sheet 8 from falling off. At this time, since the graphite sheet 7 has flexibility, it is interposed substantially without gaps in both the sand molds 4a and 4b. Even if the graphite sheet 7 is sandwiched between the sand molds 4a and 4b from above and below, the shape does not greatly change, and therefore, the graphite sheet 7 does not protrude from the sand molds 4a and 4b randomly. Further, the graphite sheet 8 also has cores 6a, 6b.
Can be attached to both of them without any gap. Although FIG. 4 (a) shows only the sand molds 4a and 4b for convenience of explanation, in the actual casting process, the graphite sheet 8 was attached to the sand molds 4a and 4b as shown in FIG. Core 6a,
6b is arranged.

The graphite sheets 7 and 8 used in the present embodiment are gather tapes whose sections have a pitch of about 1 mm and a wave height of about 0.1 mm. The reason for using such a gather tape is to make the graphite sheet more flexible to facilitate the work.

An adhesive layer is provided on one side of the graphite sheet 8, and for that purpose the graphite sheet 8 is attached and fixed to the cores 6a and 6b. FIG. 6 shows the cores 6a and 6b.
1 is a cross-sectional view of a sealing material for casting according to an embodiment of the present invention, including a graphite sheet 8 attached to a sealing material. The sealing material for casting 10 is formed by bonding an adhesive layer 12 and a release paper 14 to a graphite sheet 8.
Are stacked. When the graphite sheet 8 is attached to the cores 6a and 6b, the release paper 14 is peeled from the graphite sheet 8 side to expose the adhesive layer 12. As described above, in the sealing material for casting 10, the adhesive layer 12 is attached to the graphite sheet 8.
Is attached in advance, so that the core 6a can be easily and quickly.
The graphite sheet 8 can be stuck so as to cover the mating portion 6b. In the sealing material for casting 10 shown in FIG. 6, the adhesive layer 12 is directly adhered to the graphite sheet 8. It may be indirectly attached to the graphite sheet 8 via the shape.

In a foundry where a lot of dust and the like are floating, if the adhesive layer 12 is exposed for a long time,
It becomes difficult to attach the graphite sheet 8 to the cores 6a and 6b due to dust and the like adhering to the core. However, in the sealing material for casting 10 shown in FIG. 6, since the adhesive layer 12 is covered with the release paper 14, adhesion of dust to the adhesive layer 12 can be prevented. Therefore, if the release paper 14 is peeled off immediately before sticking, it is possible to effectively prevent the graphite sheet 8 from falling off from the cores 6a and 6b.

Next, a gate 20 connected to the mold (cavity) 22 formed by the sand molds 4a, 4b and the cores 6a, 6b is formed in the sand mold 4a.
As shown in (b), the core 6a, 6b with the graphite sheet 8 attached thereto is arranged in two sand molds 4a, 4b between which the graphite sheet 7 is interposed, and the mold 20 is inserted from the gate 20 into the mold.
Pour molten metal into 2. In FIGS. 7A and 7B, illustration of the graphite sheets 7 and 8 is omitted to simplify the drawings.

At this time, since the graphite sheet 7 is interposed between the sand molds 4a and 4b without any gap, the sand molds 4a and 4b
The molten metal does not substantially flow during the heating. Further, since the graphite sheet 8 covering the mold matching portion across the cores 6a and 6b is attached to the cores 6a and 6b, molten metal may flow between the cores 6a and 6b. Practically no. Further, among the graphite sheets 7 and 8, particularly the graphite sheet 8 comes into contact with a high-temperature molten metal, but since it has excellent heat resistance, it hardly causes deterioration in quality.

Next, after the molten metal in the mold 22 cools and hardens, the sand molds 4a and 4b and the cores 6a and 6b are broken to take out a casting. The flanged pipe 1 shown in FIG. 1 can be obtained through a predetermined process such as cutting off the gate 20. At this time, since the molten metal does not flow between the sand molds 4a and 4b and between the cores 6a and 6b, no casting is generated in the cast product. Further, even if casting is generated in the cast product, the casting is smaller and thinner than usual by using the graphite sheets 7 and 8. Therefore, the work of removing the casting can be easily performed in a short time.

According to the casting method of the present embodiment,
Since the graphite sheet 7 does not protrude randomly between the sand molds 4a and 4b, there is no occurrence of a defective surface shape in the cast product. In the present embodiment, the cores 6a, 6b
Since the graphite sheet 8 attached to the pipe comes into contact with the molten metal, a concave portion due to the thickness of the graphite sheet 8 is formed on the inner surface of the pipe 1 with the flange. However, even if such a concave portion is formed on the inner surface of the pipe which is hardly visible, it does not affect the product value at all.

The sulfur content of the graphite sheets 7 and 8 used in the present embodiment is set to 1000 ppm or less. Therefore, the sulfur content does not hinder the formation of the spherical crystals of the ductile cast iron, and the casting can be prevented without affecting the cast product even when the ductile cast iron is cast.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above-described embodiments, and various design changes can be made.
For example, in the above-described embodiment, the graphite sheet 7 is interposed between the sand molds 4a and 4b. However, the graphite sheet 7 may be stuck over the sand molds 4a and 4b so as to cover these matching portions. Good. The graphite sheet 8 may be interposed between the cores 6a and 6b. That is, it is optional whether to arrange the graphite sheet between adjacent molds or to attach and arrange the graphite sheet so as to cover the matching portion.

However, it is better to attach a graphite sheet so as to cover the matching portion, since it is sufficient to attach the graphite sheet to the matching portion after combining a plurality of molds. Work is easier than in the case of combining a plurality of molds with a sheet interposed. Also, it is better to attach the graphite sheet so as to cover the matching part, compared to the case where the graphite sheet is interposed between adjacent molds.
It is possible to more effectively prevent the molten material from flowing between the molds. Therefore, it is often possible to further suppress the occurrence of casting.

In the above embodiment, the sand mold 4a,
4b has a thickness of 0.4%.
However, the thinner the graphite sheet 7, the thinner the cast formed in case of emergency.
Therefore, it is preferable to make the thickness of the graphite sheet 7 as thin as possible unless a problem in strength occurs.

The closer the graphite sheet 7 interposed between the sand molds 4a and 4b is to a position closer to the inner end of the mold matching portion, the smaller the cast-up formed in the event of an emergency. . Therefore, it is preferable that the graphite sheet 7 is disposed as close as possible to the inner end of the mold matching portion, and the end of the graphite sheet 7 is
It is preferable to be located on the same plane as the end faces of a and 4b.

[0033]

As described above, according to the first aspect, the graphite sheet having flexibility or flexibility is provided so that the molten material does not flow between the adjacent molds. Since there is no gap in the vicinity of the end of the mating portion on the side in contact with the molten material, substantially no casting occurs due to the flow of the molten material from the vicinity of the end to the space between adjacent molds. Also, even if casting occurs,
Since the graphite sheet is used, the casting is smaller and thinner than usual, and the finishing process such as removing the casting is easy.

According to the first aspect, since the graphite sheet has excellent heat resistance, even when a high-temperature molten material is used, the graphite sheet hardly deteriorates and deteriorates. Since it does not protrude randomly between adjacent molds, substantially no defective shape of the cast product occurs, and further, the handling is easy and the working efficiency can be improved.

According to the second aspect of the present invention, the graphite sheet may be arranged in the mold matching portion after combining a plurality of molds. The work is easier in comparison. Further, since the graphite sheet is arranged so as to cover the mold matching portion, compared to the case where the graphite sheet is arranged between adjacent molds, the flow of the molten material between the molds is more effectively prevented. be able to. Therefore, it is possible to further suppress the occurrence of casting.

According to the third aspect, since the graphite sheet is arranged between the adjacent molds, a concave portion corresponding to the thickness of the graphite sheet is not formed on the surface of the casting as in the second aspect. .

In the casting method according to the second aspect of the present invention, the adhesive layer covered with a peelable member is attached to a graphite sheet.
It can be used so as to cover the mold matching portion over the adjacent molds, and can improve the work efficiency for arranging the graphite sheet. In addition, since the adhesive layer is covered with the peelable member, it is possible to prevent dust from adhering to the adhesive layer and prevent the graphite sheet from falling off from the casting.

[Brief description of the drawings]

FIG. 1 is a perspective view of a flanged pipe cast by an embodiment of the casting method of the present invention.

FIG. 2A is a perspective view of a wooden main mold formed in a casting method according to an embodiment of the present invention.
(B) is a perspective view of a wooden core type.

FIG. 3A is a sectional view of a sand mold formed by a casting method according to an embodiment of the present invention, and FIG. 3B is a perspective view of a core.

4 (a) is a cross-sectional view showing a state where a graphite sheet is interposed in the sand mold of FIG. 3 (a), and FIG. 4 (b) is a sectional view of FIG.
It is the elements on larger scale of the area | region enclosed with the circle in (a).

FIG. 5 is a cross-sectional view showing a state where a graphite sheet is attached to a core of FIG. 3 (b).

FIG. 6 is a cross-sectional view of one embodiment of the sealing material for casting of the present invention.

FIG. 7A is a cross-sectional view along a longitudinal direction of a pipe showing a state of pouring by combining the sand mold of FIGS. 4A and 4B and the core of FIG. 5; FIG. 7B is a cross-sectional view along the radial direction of the pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flanged pipe 2 Wooden main mold 3 Wooden core mold 4a, 4b Sand mold 5a, 5b Metal frame 6a, 6b Core 7, 8 Graphite sheet 10 Casting sealing material 12 Adhesive layer 14 Release paper 20 Spout 22 In mold

Continued on the front page (72) Inventor Yoichi Nishimoto 1802 Higashitakashino, Minano-machi, Nakatado-gun, Kagawa Prefecture Inside Sanki Casting Ironworks Co., Ltd. (72) Inventor Kazuhiro Maekawa 2791 Matsuzaki, Takuma-cho, Mitoyo-gun, Kagawa Toyo Carbon Co., Ltd. (72) Inventor Yasuhiro Takenaka 2791 Matsuzaki, Takuma-cho, Mitoyo-gun, Kagawa Toyo Carbon Co., Ltd. (72) Inventor Yoshiomi Tada 2181-2 Nakahime, Onohara-cho, Mitoyo-gun, Kagawa Prefecture Toyo Carbon Co., Ltd. (72) Inventor Tomio Ando 2181-2 Nakahime, Onohara-cho, Mitoyo-gun, Kagawa Prefecture F-term (reference) 4E092 AA05 BA11 EA02 FA10

Claims (4)

[Claims] In a casting method using a plurality of molds in combination, a graphite sheet is provided near an end of a mold matching portion of the mold near a side in contact with the molten material so that the molten material does not flow between adjacent molds. A casting method, wherein a molten material is introduced into a mold in an arranged state. 2. The casting method according to claim 1, wherein the graphite sheet is disposed so as to cover a mold matching portion across the adjacent molds at the end portion. 3. The casting method according to claim 1, wherein the graphite sheet is disposed between molds near the end. 4. A sealing material for casting, wherein an adhesive layer covered with a peelable member is attached to a graphite sheet.