JP2553923B2 - Method for manufacturing cast ceramic body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a cast ceramic body,
In particular, the present invention relates to a method of manufacturing a cast ceramic body formed by casting and solidifying a metal around a ceramic cylinder having a small strength and a large diameter.

(Prior art) When a wear-resistant adiabatic casting is produced by casting a ceramic cylinder with a metal such as aluminum or cast iron, an intermediate layer having heat insulation and flexibility is provided on the periphery of the cast cylinder of the ceramic cylinder. Provided to alleviate the thermal shock when the molten metal at high temperature comes into contact with the ceramic cylinder and absorb the internal compressive stress generated when the molten metal cools and solidifies and contracts, thereby preventing the ceramic cylinder from being damaged. The technology is known (for example, Japanese Patent Laid-Open No. 61-115662).

(Problems to be Solved by the Invention) When the strength of the ceramic cylinder is small and the diameter thereof is large, the ceramic cylinder is damaged by internal compressive stress when the molten metal is cooled and solidified unless the intermediate layer is thickened. However, when the thickness of the intermediate layer is increased, only a part of the layer contracts to leave the intermediate layer having a small strength, and the bonding strength of this portion becomes weak.

The present invention has been made in view of such circumstances, and when a ceramic cylinder having a small strength and a large diameter is cast by aluminum or cast iron, the cylinder is damaged by thermal shock or cooling shrinkage of the molten metal. It is an object of the present invention to provide a method for producing a ceramic cast-in body in which the cylinder and the cast-in-roll metal are firmly bonded to each other.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms an intermediate layer having a heat insulating property and flexibility in a predetermined thickness on the outer peripheral portion of a ceramic cylinder, and The present invention is characterized in that a large number of nail members penetrating and projecting from the inner peripheral side to the outer peripheral side are arranged at a predetermined pitch, and a molten metal is cast around the intermediate layer and solidified.

(Example) Hereinafter, the present invention will be described in detail according to an example.

The drawings show the manufacturing process of the cast ceramic body according to the present invention. FIG. 1 is a sectional view showing a state in which the ceramic fiber molded body is mounted on the outer peripheral portion of the ceramic cylinder, and FIG. 2 is FIG. FIG. 3 is a cross-sectional view showing a state in which a styrofoam sheet is wound around the outer periphery of the ceramic fiber molded body in FIG. 3, and FIG. 3 is a cross-sectional view showing a state in which the cast toy body of FIG. 2 is set in a full-mode casting flask. FIG. 4 is a sectional view of the completed cast ceramic body.

First, as shown in FIG. 1, the thickness of the intermediate layer is set on the outer peripheral side of the mullite ceramic cylinder (1) having an outer diameter of 110 mm.
Insert a 10 mm cylindrical ceramic fiber molding (2). An iron nail (3) having a diameter of 1.6 mm and a length of 15 mm, which penetrates from the inner peripheral side to the outer peripheral side of the ceramic fiber molded body (2), has a circumferential direction of 40 mm and an axial direction of 10 mm. A large number of them are attached at a pitch, and as a result, the tip of the iron nail (3) is projected on the outer peripheral surface of the molded body (2) by 5 mm at a predetermined interval.

Next, the tip of the iron nail (3) is heated by an appropriate method, and as shown in FIG. 2, a foamed polystyrene sheet (4) having a thickness of 10 mm is formed on the outer peripheral surface of the ceramic fiber molded body (2). It is closely wound to form a cast toy body (5). At this time, the tip of the iron nail (3) melts the Styrofoam sheet (4) and rushes into the sheet (4).

Thirdly, the cast toy body (5) is set in the full-mold casting flask (6) as shown in FIG. The setting process will be described in detail. The casting frame (6) is composed of an inner box (7) having a ventilation structure with an open upper end, and an outer box (9) defining a decompression chamber (8) on the outer periphery thereof. The outer box (9) is provided with a conduit (11), one end of which communicates with the decompression chamber (8) and the other end of which is connected to a vacuum pump (not shown).

And, the sprue body gate model (12) is adhered to the above-mentioned cast toy body (5), and the surface of the cast toy body (5) is coated if necessary, and the cast toy body (5) is provided to the above-mentioned flask (6). It is set in the inner box (7) so that the upper end of the gate model (12) appears on the upper surface of the inner box (7), and the casting sand containing no binder in the inner box (7). A mold material (13) such as the above is filled to the upper end, and the upper surface of the inner box (7) excluding the gate model (12) is covered with a heat resistant airtight sheet (14).

Fourthly, a vacuum pump (not shown) is operated to discharge the air in the inner box (7) through the pipe line (11) and the decompression chamber (8) so that the inner box (7) is in a negative pressure state. To As a result, the mold material (13) containing no binder is solidified in the inner box (7) with the stuffed body (5) to be cast therein.

Fifthly, when molten metal of ductile cast iron (15) is poured into the inner box (7) from the upper end of the sprue model (12), the styrofoam sheet in the sprue model (12) and the cast-in toy body (5). (4) is combusted and vaporized, and the hollow portion generated by this is filled with the molten metal in a substitutional manner. At that time, the ceramic fiber molded body (2) in the stuffed object (5) to be cast is thermally insulated. The effect is exerted, and the thermal shock on the ceramic cylinder (1) is alleviated. The tip of the iron nail (3) protruding to the outer peripheral portion of the ceramic fiber molded body (2) comes into contact with the molten metal, but the melting point of the iron nail (3) is that of the ductile cast iron (15). Since it is higher than the above, the iron nail (3) does not melt.

The molten metal eventually cools and solidifies to shrink, and internal compressive stress is generated at this time, but the ceramic fiber molded body (2) in the cast body (5) shrinks inward and absorbs the compressive stress. Therefore, destruction of the ceramic cylinder (1) is prevented. On the other hand, an internal compressive stress is transmitted to the iron nail (3) when the molten metal is solidified, and the base end portion of the iron nail (3) is pressed by the outer peripheral surface of the ceramic cylinder (1) but bends due to the resistance of the cylinder (1). Therefore, the cylinder (1) is not destroyed. The pressing force of the iron nail (3) remains even after the molten metal is completely solidified and cooled, whereby the ceramic cylinder (1) and the cast metal are firmly joined.

Sixth, after a lapse of a predetermined time, the operation of the vacuum pump is stopped to release the negative pressure state in the inner box (7), so that the particles of the mold material (13) can move freely. , The inner box (7)
From the inside, the cast ceramic body (1
6) Take out.

In the examples, ductile cast iron (15) was used as the cast metal, but the present invention is widely applicable to low melting metals, high melting metals such as cast steel and special steel. Further, in the embodiment, the iron nail (3) is used as the joining member between the ceramic cylinder (1) and the cast metal, but the joining member has a melting point higher than that of the cast metal (for example, stainless steel in the case of cast steel). In this embodiment, the ceramic fiber molding (2) is mounted on the outer peripheral portion of the ceramic cylinder (1), but any material having heat insulating flexibility may be used.

As a method of mounting the ceramic fiber molded body (2), in the embodiment, a cylindrical shape is inserted and fitted into the ceramic cylinder (1), but a sheet-shaped shape is wound around the cylinder (1). Good.

Further, in the embodiment, the expanded polystyrene sheet (4) is wound around the outer periphery of the ceramic fiber molded body (2) and is cast by the full mode casting method, but it is cast by another casting method that does not use the expanded polystyrene sheet (4). It doesn't matter.

(Effects of the Invention) According to the present invention as described above, the ceramic fiber molded body mounted on the outer peripheral portion of the ceramic cylinder relaxes the thermal shock of the molten metal to the ceramic cylinder during casting. The internal compressive stress generated when the molten metal is cooled and solidified has a thickness that does not directly affect the ceramic cylinder, so that the ceramic cylinder is not destroyed even when it is cast around the ceramic cylinder having small strength and large diameter. .

Further, a large number of iron nails that are attached to the ceramic fiber molded body so as to penetrate from the inner peripheral side to the outer peripheral side at a predetermined pitch press the outer peripheral surface of the ceramic cylinder by internal compressive stress during solidification cooling of the cast metal melt. Then, the joint strength between the cylinder and the cast metal is increased,
The iron nail is selected so that it is flexible enough to be flexed by the resistance of the ceramic cylinder, so that the cylinder will not be broken.

That is, according to the present invention, it is possible to manufacture a ceramic cast-in body in which a ceramic cylinder having a small strength and a large diameter is used as a core, and the cylinder and the cast-in metal are firmly bonded to each other.

[Brief description of drawings]

The drawings show the manufacturing process of a cast ceramic body according to the present invention. FIG. 1 is a sectional view showing a state in which a ceramic fiber molded body is mounted on the outer peripheral portion of a ceramic cylinder, and FIG. FIG. 3 is a cross-sectional view showing a state in which a styrofoam sheet is wound around the outer periphery of a ceramic fiber molded body, and FIG. 3 is a sectional view showing a state in which the to-be-cast stuffed body of FIG. Four
The figure is a cross-sectional view of the completed cast ceramic body. (1): Ceramic cylinder (2): Ceramic fiber molded body (3): Iron nail (4): Styrofoam sheet (5): Body to be cast (6): Casting frame (15): Ductile cast iron (16): Ceramic cast body

Claims (1)

(57) [Claims] 1. A ceramic cylinder (1) is provided with an intermediate layer (2) having a heat insulating property and flexibility at a predetermined thickness on the outer peripheral portion of the ceramic cylinder (1), and the intermediate layer (2) extends from the inner peripheral side to the outer peripheral side. A method for producing a ceramic cast-in body, characterized in that a large number of nail members (3) projecting through are arranged at a predetermined pitch, and a molten metal is cast around the intermediate layer (2) and solidified.