JPH02137660A - Production of ceramics internal chill body - Google Patents

Abstract

PURPOSE:To obtain the ceramics internal chill body which is secure in the joint part by forming an intermediate layer having a heat insulating property and resilience to the outer peripheral part of a ceramics cylinder to a prescribed thickness, disposing many nail members penetrating the intermediate layer from the inner peripheral side to the outer peripheral side thereof, casting a molten metal into the circumference of the intermediate layer and then solidifying the molten metal. CONSTITUTION:A cylindrical ceramics fiber molding 2 is fitted to the cylinder 1 made of mullite-base ceramics and iron nails 3 are mounted thereto. The tips of the iron nails are heated and a foamed styrol sheet is tightly fitted thereto to form the body 5 to be internally chilled. The body to be internally chilled is set in a molding flask 6 for full-mold casting and a sprue pattern 12 made of foamed styrol is adhered thereto. Molding sand 13 which does not contain a binder is packed into an inside box 7 up to the top end and is covered by a heat resistant hermetic sheet 14. A vacuum pump is operated to develop a negative pressure state in the inside box via a pressure reducing chamber 8 by which the molding material 13 is solidified. The foamed styrol sheet 4 is burned to evaporate and is substitutively packed with the molten metal when the melt of a ductile cast iron 15 is poured therein. The ceramics internal chill body which consists of the ceramics cylinder as its core body and is joined securely to the internal chill metal is produced in this way.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a ceramic cast body, and particularly to a ceramic cast body made by casting and solidifying metal around a ceramic cylinder having low strength and a large diameter. Relating to a manufacturing method.

(Prior art) When manufacturing a wear-resistant heat insulating casting by surrounding a ceramic cylinder with a metal such as aluminum or cast iron, an intermediate layer with heat insulating properties and flexibility is added to the edge of the cast part of the ceramic cylinder. is provided to alleviate the thermal shock when the high-temperature molten metal contacts the ceramic cylinder, and absorb the internal compressive stress that occurs when the molten metal cools, solidifies, and contracts, thereby preventing damage to the ceramic cylinder. Techniques to prevent this are well known (for example, Japanese Patent Application Laid-Open No. 115662/1983).
.

(Problems to be Solved by the Invention) When the strength of the ceramic cylinder is low and the diameter is large, the ceramic cylinder will be damaged by internal compressive stress when the molten metal is cooled and solidified unless the intermediate layer is made thick. However, when the intermediate layer is made thicker, only a portion of the layer contracts, leaving an intermediate layer with low strength, resulting in a problem that the bonding strength in this portion is weak.

The present invention was made in view of these circumstances, and
When a ceramic cylinder with low strength (and large diameter) is cast with aluminum or cast iron, the cylinder will not be damaged by thermal shock or cooling shrinkage of the molten metal.
Another object of the present invention is to provide a method for manufacturing a ceramic cast body in which the cylinder and the cast metal are firmly joined.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms an intermediate layer with a predetermined thickness on the outer periphery of a ceramic cylinder, which has heat insulating properties and flexibility. It is characterized in that a large number of nail members projecting through from the inner circumferential side to the outer circumferential surface are arranged at a predetermined pitch, and molten metal is cast and solidified around the intermediate layer.

(Example) Hereinafter, the present invention will be explained in detail according to examples.

The drawings show the manufacturing process of a ceramic cast body according to the present invention, and FIG. 1 is a cross-sectional view showing a state in which a ceramic Aiba molded body is attached to the outer periphery of a ceramic cylinder, and FIG. Fig. 3 is a cross-sectional view showing a state in which a foamed polystyrene sheet is wrapped around the outer periphery of a ceramic Aaiba molded body, and Fig. 3 is a cross-sectional view showing a state in which the cast body shown in Fig. 2 is set in a flask for full mold casting. , FIG. 4 is a cross-sectional view of the completed ceramic casting body.

First, as shown in Fig. 1, a cylindrical ceramic fiber molded body (2) with a thickness of 10 mm is placed as an intermediate layer on the outer periphery of a mullite ceramic cylinder (1) with an outer diameter of 110 mm.
Insert. The ceramic fiber molded body (2) includes:
Penetrating from the inner circumferential side to the outer circumferential side, the diameter is 1.6 mrn,
An iron nail (3) with a length of 15 mrn is 40 mm in the circumferential direction,
Multiple pieces are installed at a pitch of 10mm in the axial direction,
As a result, the iron nails (3) are placed on the outer peripheral surface of the molded body (2).
5mm of the tips protrude evenly at predetermined intervals.

Next, after heating the tip of the iron nail (3) using an appropriate method, a 10 mm thick styrene foam sheet (4) is placed on the outer peripheral surface of the ceramic fiber molded body (2), as shown in FIG. It is tightly wound to form a cast body (5). At this time, the tip of the iron nail (3) melts the Styrofoam sheet (4) and plunges into the sheet (4).

Thirdly, as shown in FIG. 3, the toy body (5) is
Set in the flask (6) for full mold casting. To explain this setting process in detail, the flask (6) consists of an inner box (7) with an open upper end and a ventilation structure, and an outer box (9) that defines a decompression chamber (8) around the outer periphery of the inner box (7). and
The outer box (9) has a conduit (11) that communicates with the decompression chamber (8) at one end and connects to a vacuum pump (not shown) at the other end.
) is provided.

Then, a sprue model (12) made of expanded polystyrene is adhered to the to-be-cast body (5), and the surface is coated if necessary, and the to-be-cast body (5) is attached to the flask (6). ) The upper end of the sprue model (12) is inside the inner box (7).
) and set it so that it appears on the top surface of the inner box (7).
An inner box (7) filled with molding material (13) such as molding sand that does not contain a binder up to the upper end and excluding the sprue model (12).
The upper surface of the container is covered with a heat-resistant airtight sheet (14).

Fourth, a vacuum pump (not shown) is activated, and the pipe line (
11) and the vacuum chamber (8) to exhaust the air inside the inner box (7) to bring the inside of the inner box (7) into a negative pressure state. As a result, the molding material (13) containing no binder is solidified within the inner box (7) with the cast body (5) contained therein.

Fifth, when the molten metal of the ductile cast iron (15) is injected into the inner box (7) from the upper end of the sprue model (12), the foamed polystyrene sheet ( 4) is combusted and vaporized, and the resulting cavity is filled with the molten metal in an displacement manner. At this time, the ceramic fiber molded body (2) in the cast-filled body (5) has a heat insulating effect. As a result, thermal shock to the ceramic cylinder (1) is alleviated. Note that the tip of the iron nail (3) protruding from the outer periphery of the ceramic fiber molded body (2) will come into contact with the molten metal;
Since the melting point of the iron nail (3) is higher than that of ductile cast iron (15), the iron nail (3) will not melt.

The molten metal eventually cools and solidifies and contracts, generating internal compressive stress, but the ceramic fiber molded body (2) in the cast body (5) contracts inward and absorbs the compressive stress. Therefore, destruction of the ceramic cylinder (1) is prevented. On the other hand, the internal compressive stress during solidification of the molten metal is transmitted to the iron nail (3), and its base end presses against the outer peripheral surface of the ceramic cylinder (1), but it bends due to the resistance of the cylinder (1). Therefore, the cylinder (1) will not be destroyed. The pressing force of the iron nail (3) remains even after the molten metal has completely solidified and cooled, and this causes the ceramic cylinder (1
) and the cast metal are firmly joined.

Sixth, after a predetermined period of time has elapsed, the operation of the vacuum pump is stopped to release the negative pressure inside the inner box (7), thereby freeing the movement of each particle of the mold material (13). , the inner box (7)
A ceramic cast body (1
6) Take out.

In the examples, ductile cast iron (
15), but the present invention is widely applicable to metals ranging from low melting point metals to high melting point metals such as cast steel and special steel. In addition, in the example, an iron nail (3) was used as a joining member between the ceramic cylinder (1) and the cast metal, but the joining member is made of a material with a higher melting point than the cast metal (for example, in the case of cast steel, stainless steel is used). nails).

Further, in the embodiment, the ceramic fiber molded body (2) is attached to the outer periphery of the ceramic cylinder (1), but any material may be used as long as it has heat insulating properties and flexibility.

In addition, as a method of attaching the ceramic fiber molded body (2), in the embodiment, a cylindrical body is attached to the ceramic cylinder (1).
However, a sheet-like material may be wound around the cylinder (1).

Furthermore, in the example, a foamed polystyrene sheet (4) was wrapped around the outer periphery of the ceramic fiber molded body (2) and cast by a full mold casting method.
It may be cast using other casting methods that do not use 4).

(Effects of the Invention) According to the present invention as described above, the ceramic fiber molded body attached to the outer periphery of the ceramic cylinder not only alleviates the thermal shock of the molten metal to the ceramic cylinder during casting, but also The thickness is set so that the internal compressive stress that occurs when the molten metal cools and solidifies does not directly affect the ceramic cylinder, so even when casting a ceramic cylinder with low strength and a large diameter, the cylinder will not be destroyed. .

In addition, a large number of iron nails are attached to the above-mentioned ceramic fiber molded body at a predetermined pitch and protrude from the inner circumferential side to the outer circumferential side, and press the outer circumferential surface of the ceramic cylinder due to internal compressive stress during solidification and cooling of the molten metal in the casting. This increases the strength of the joint between the cylinder and the cast metal, but the iron nail is selected to have such strength that it will bend due to the resistance of the ceramic cylinder, so the cylinder will not be destroyed. Never.

That is, according to the present invention, it is possible to manufacture a ceramic cast body in which a ceramic cylinder with low strength and a large diameter is used as a core body, and the cylinder and the cast metal are firmly joined.

[Brief explanation of the drawing]

The drawings show the manufacturing process of the ceramic cast body according to the present invention, and FIG. 1 is a cross-sectional view showing a state in which a ceramic fiber molded body is attached to the outer periphery of a ceramic cylinder, and FIG. FIG. 3 is a cross-sectional view showing a state in which a foamed polystyrene sheet is wrapped around the outer periphery of a ceramic fiber molded body; FIG. 3 is a cross-sectional view showing a state in which the cast body shown in FIG. Figure 4 is a cross-sectional view of the completed ceramic casting body. Ceramics Cylindrical ceramic fiber molded iron nail Styrofoam sheet Casting body: Casting flask: Ductile cast iron: Ceramic casting body

Claims (1)

[Claims] An intermediate layer (2) having heat insulation and flexibility is formed at a predetermined thickness on the outer periphery of the ceramic cylinder (1), and the intermediate layer (2)
A ceramic casting toy, characterized in that a large number of nail members (3) projecting through from the inner circumferential side to the outer circumferential side are arranged at a predetermined pitch, and molten metal is cast and solidified around the intermediate layer (2). How the body is manufactured.