JP2824380B2 - Centrifugal casting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal casting method for casting a cylindrical body by centrifugal casting by pouring a molten metal into a mold which is driven to rotate for centrifugal casting.

[0002]

2. Description of the Related Art In a conventional centrifugal casting method, a molten metal is poured into the casting mold and centrifugally cast while rotating a casting mold for horizontal centrifugal casting. After solidifying the body, the tubular body was taken out of the mold.

[0003]

When a cylindrical body is cast by such a conventional method, the molten metal injected into the mold is:
Heat is absorbed from the outer diameter side by the mold and solidification proceeds from the outer diameter side to the inner diameter side, and the innermost diameter side of the molten metal finally becomes a solidified part, so that the inner peripheral part of the tubular body ,
An unhealthy layer is generated due to the collection of low melting point substances and the formation of shrinkage cavities. The occurrence of such unhealthy class
In many cases, there was a problem in the product quality of the cylindrical body.
Therefore, although it is performed as necessary to remove the inner peripheral portion of the cylindrical body including at least the unhealthy layer by casting after casting, the removal of the inner peripheral portion by the machining is performed. In such a case, the machining requires a lot of labor and cost, and an extra margin must be taken, which leads to a new problem such as an increase in the weight of the cast product. The present invention has been made in view of such a situation, and has as its object to provide means capable of solving the quality problem without causing the above-described new problem.

[0004]

A centrifugal casting method according to the present invention (hereinafter, referred to as the present invention) is a method of centrifugal casting having openings at both ends, which is arranged in advance in a vertical direction. While rotating the mold at a high rotational speed capable of holding the molten metal on the inner surface of the mold by centrifugal force, the molten metal through the upper opening of the both end openings is sprayed and supplied to the inner surface of the mold, By vertical centrifugal casting, after solidifying most of the molten metal, the rotation of the mold is stopped, or to a low rotation speed at which the molten metal cannot be held on the inner surface of the mold by centrifugal force, It is characterized in that the unsolidified molten metal is caused to flow out through the lower one of the openings at both ends by lowering the rotation speed.

[0005]

According to the method of the present invention, the molten metal sprayed and supplied to the inner surface of the mold rotating at the high rotation speed is vertically centrifugally cast while being held on the inner surface of the mold by centrifugal force. Solidification proceeds from the side to the inner diameter side, but at the time of most solidification of the molten metal, a portion causing the generation of the unhealthy layer may be present in the unsolidified molten metal on the inner peripheral side of the molten metal. Under such conditions, under the conditions, the rotation of the mold is stopped, or by lowering the rotation speed of the mold to a low rotation speed at which the molten metal cannot be held on the inner surface of the mold by centrifugal force, The unsolidified molten metal including the portion that causes the generation of the unhealthy layer can flow out below the mold, and the outflow can suppress the generation of the unhealthy layer.

[0006]

Therefore, according to the method of the present invention, the generation of the unhealthy layer is suppressed, and the machining for removing the unhealthy layer which has been conventionally performed on the cast product is unnecessary. Therefore, much trouble and cost for the machining are not required, and it is not necessary to take extra removal allowance, so that an increase in the weight of the cast product can be avoided. As a result, it becomes possible to avoid the occurrence of the unhealthy layer while avoiding a new problem associated with the conventional machining, and
The object of the present invention is achieved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

First, a centrifugal casting device used for carrying out the method of the present invention will be described. In FIG. 1, reference numeral 1 denotes a mold for centrifugal force casting (specifically, a cylindrical metal frame), and the mold 1 is arranged vertically, and is rotated around a vertical axis by rotation driving means (not shown). It is designed to be rotationally driven.

Both ends 1a, 1 of the vertical mold 1
In the upper opening 1a of b, a hot water storage section 2a for temporarily storing the molten metal prepared for pouring, and the hot water storage section 2a
A pouring tool 2 provided with a combination of a hot water supply pipe 2b having a lower end opening toward the inner surface of the mold 1 is provided for receiving the flow of the molten metal therein and spraying and supplying the molten metal to the inner surface of the mold 1. In addition, a pressure other than gravity may be applied to the molten metal in the hot water storage section 2a in order to reliably realize the spray supply.

The pouring tool 2 is provided in the upper opening 1a.
An upper annular member 3 functioning as an upper dam for molten metal supplied for centrifugal casting into the mold 1 via the above is mounted.

On the other hand, both end openings 1a, 1b of the mold 1 are provided.
The lower annular member 4 functioning as a lower dam for the molten metal supplied for centrifugal force casting is mounted in the lower opening 1b. At the inner peripheral edge of the lower annular member 4, a hot water pipe 4 is arranged such that a lower end is opened inside a ladle 5 for receiving the outflow molten metal which is arranged below the mold 1.
a is attached in a hanging state.

The procedure for carrying out the method of the present invention using such a centrifugal casting apparatus will be specifically described below.

First, the vertically arranged mold 1 is rotated at a high rotational speed at which the molten metal can be held on the inner surface of the mold 1 by centrifugal force, and the upper side of the openings 1a and 1b at both ends of the mold 1 is rotated. The molten metal via the opening 1a (more specifically, the molten metal via the pouring tool 2) is sprayed and supplied to the inner surface of the mold 1 to perform vertical centrifugal casting while holding the molten metal on the inner surface. And most of the molten metal (specifically, 70 to 8
0%), the mold 1 is stopped rotating, or the rotational speed of the mold 1 is reduced to a low rotational speed at which the molten metal cannot be held on the inner surface of the mold 1 by centrifugal force.
The unsolidified molten metal is caused to flow downward through the lower opening 1b of the both ends 1a and 1b of the mold 1 (more specifically, via the hot water pipe 4a), and the molten metal flowing out is taken out of the ladle. Receive at 5.

According to the method of the present invention performed in such a procedure, the molten metal sprayed and supplied to the inner surface of the mold 1 rotating at the high rotational speed is held by the centrifugal force while being held on the inner surface of the mold 1 by the vertical centrifugal force. It is cast and solidification proceeds from the outer diameter side to the inner diameter side of the mold, but at the time of most solidification of the molten metal, the portion causing the formation of an unhealthy layer is unsolidified on the inner peripheral side of the molten metal. Since it can be present in the molten metal,
Under these conditions, the rotation of the mold 1 is stopped, or the rotation speed of the mold 1 is reduced to a low rotation speed at which the molten metal cannot be held on the inner surface of the mold 1 by centrifugal force. By causing the unsolidified molten metal including the portion causing the generation to flow downward, the generation of the unhealthy layer can be suppressed by the flow of the molten metal.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the accompanying drawings.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a method of the present invention.

[Explanation of symbols]

 1 mold 1a upper opening 1b lower opening

Claims (1)

(57) [Claims] 1. A centrifugal casting mold (1) having openings (1a) and (1b) at both ends is vertically arranged in advance, and the vertical mold (1) is placed in the mold (1) by centrifugal force. 1) While rotating at a high rotational speed capable of holding the molten metal on the inner surface, the molten metal passing through the upper opening (1a) of the both-end openings (1a) and (1b) is removed from the mold (1). After the majority of the molten metal is solidified by being sprayed and supplied to the inner surface to perform vertical centrifugal casting, the rotation of the mold (1) is stopped, or the molten metal is centrifugally applied to the inner surface of the mold (1). By lowering the rotation speed of the mold (1) to a low rotation speed that cannot be held,
A centrifugal casting method in which unsolidified molten metal flows out through the lower opening (1b) of the openings (1a) and (1b) at both ends.