JPH01313127A - Casting method using lost foam pattern - Google Patents

Abstract

PURPOSE:To prevent the deformation of a lost foam pattern by fixing flat plate-like support pattern in a flask, forming an upper side sand mold and forming the lost foam pattern and a lower side sand mold after turning over the flask. CONSTITUTION:The rectangular support pattern 2 is fixed to the flask 1 turned sideway and the lost foam pattern is formed on one side face as the shape cutting in almost half. The sand is packed into the upper space demarcated with a cover member 3 and after vibrating, the flask 1 is turned over at 180 deg. angle. Successively, the support pattern 2 is taken off and at the time of setting the lost foam pattern 9 in this part, the pattern 9 is stuck under gapless condition in a first sand mold 8. Further, the sand is packed into the remained space in the flask 1 to form a second sand mold. As the lost foam pattern 9 is supported and reinforced from back face in the first sand mold 8, at the time of forming the second sand mold 10, the deformation of the lost foam pattern 9 can be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a casting method using a fugitive model, and more particularly, to a fugitive model casting method that can cast castings with high precision. .

Prior Art When mass producing cast products, it is common to use molds, but since molds are expensive, it is difficult to make molds when producing small to medium quantities of cast products. It is uneconomical to cast. Therefore, a fugitive model made of foamed polystyrene or the like with a shape corresponding to the object to be cast is placed in a casting flask, filled with sand, applied vibrations and pulled under reduced pressure to form a sand mold. A method often used is to set a fugitive model inside, pour molten metal into the model, and replace the model with the molten metal while melting the model to perform casting. According to this method, casting can be performed without using an expensive mold, and there is an advantage that it is economical.

However, when setting a fugitive model in a sand mold, uneven forces are inevitably applied to the fugitive model due to sand filling, vibration, and decompression. There is a problem of deformation, which reduces the precision of casting.Especially when a thin or long fugitive model is used, the deformation is significant, making it impossible to obtain a cast product in the desired shape. Ta.

In order to prevent such deformation of the fugitive model in the sand mold, a method has been proposed in which a reinforcing material is attached to the fugitive model to improve its strength (see Utility Model Application Publication No. 59-148149, etc.).

Problems to be Solved by the Invention However, with this method of attaching reinforcing materials to a fugitive model, it is extremely difficult to sufficiently improve the strength of the fugitive model when reinforcing it with the same material as the fugitive model. In addition, when reinforcing a material with a high strength different from that of the fugitive model, there are problems such as difficulty in recovering the reinforcing material after casting, which effectively prevents the deformation of the fugitive model. could not be prevented.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method for casting a fugitive model that can effectively prevent deformation of the fugitive model and cast a casting with high precision.

Structure of the Invention An object of the present invention is to place a flat support mold having at least one side of the same shape as the fugitive model in a casting flask, and place the fugitive model in the position where the fugitive model is to be set. The upper space in the flask divided into two parts by the supporting mold is filled with sand, the flask and the supporting mold are inverted, and the supporting mold is fixed with the surface having the same shape facing upward. This is achieved by taking out the support mold, setting a fugitive model in the part from which the support mold was taken out, filling the other space in the flask with sand, and performing casting.

According to the present invention, a strong sand mold is formed by filling the upper part of the casting flask with sand, applying vibration, and pulling it under reduced pressure using a supporting mold that is stronger than a fugitive mold. death,
After that, the flask and support mold are turned over, the support mold is replaced with a fugitive model, and the remaining part that has been turned over is filled with sand, so that when filling with sand, the fugitive model is
Its lower side is supported by a strongly formed sand mold, and filling with sand prevents it from deforming, making it possible to manufacture castings with excellent precision.

According to the present invention, a flat support mold having a part having the same shape as the fugitive model on at least one side is defined as a flat support mold having a flat support member having the same shape as the fugitive model and provided on both sides thereof. In addition to those parts that together have the same shape as the evanescent model, it also includes parts that have the same shape as all or part of the evanescent model only on the surface thereof, and at least , it is sufficient that the negative side has a part having the same shape as a part of the evanescent model.

In particular, it is preferable that a portion corresponding to the shape of the fugitive model is provided so that the longitudinal direction of the fugitive model coincides with that surface.

In the present invention, the material for the fugitive model is not particularly limited as long as it can maintain a certain shape and dissolves and disappears in the molten metal, but foamed polystyrene, foamed polyurethane, foamed polyethylene, etc. are preferably used. It is possible.

In the present invention, a mold coating agent is applied to the surface of the fugitive model. Preferred mold coating agents include those containing silicon oxide as a main component, particularly those consisting of silicon oxide and zirconium oxide.

EXAMPLES Hereinafter, examples of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a schematic diagram showing the steps of an investment model casting apparatus according to an embodiment of the present invention.

1rXJ(a) shows the flask l, which is placed horizontally so that it can be filled with sand from the side. As shown in FIG. 1 et al., the support mold 2 is first fixed to the flask 1. The supporting mold 2 is made of a rectangular plate, and a part having the same shape as that obtained by cutting the fugitive model in approximately half along its axis is formed on its negative side. When the support mold 2 is fixed in the flask 1 in this way, the upper space defined by the upper surface of the support mold 2 and the inner surface of the flask l is sealed by the lid member 3, and further, as shown in FIG. As shown in FIG.
The upper space is filled with sand. At this time, flask 1
For example, vibration is applied by the vibrator 7 at 10 g/sec for about 60 seconds to firmly tighten the sand.
A first sand mold 8 is formed in the upper space. After that, support type 2
The flask I, with which it is fixed, is turned over 180 degrees. As shown in FIG. 1, the first sand mold 8 is further drawn under reduced pressure by a pump (not shown) and solidified. Thereafter, the support mold 2 is removed from the flask 1, and a fugitive mold 9 whose surface is coated with a mold coating agent is set in its place. As described above, on one surface of the support mold 2, a part having the same shape as the fugitive model 9 cut in half along its axis is formed, and the fugitive model 9 is similar to the sand mold 8.
It is set on the top surface of the sand mold 8 without creating a gap between the sand mold 8 and the sand mold 8. When the fugitive model 9 is set on the upper surface of the sand mold 8 in this way, as shown in FIG. 1(e), the remaining space in the flask 1, that is, in FIG. A lower space (upper space in FIG. 1(d)) defined by the lower surface of the supporting mold 2 and the inner surface of the flask 1 is sealed by the lid member 3, and filled with sand by the filling spatula 6.

At this time, vibration is applied by the vibrator 7 in the same manner, and the second sand mold 10 is formed.

Thereafter, the second sand mold 10 is further solidified by being pulled under reduced pressure by a pump (not shown), and the first sand mold 8
A sand mold 11 is formed by the second sand mold 10. At the time of forming the second sand mold 10, the fugitive model 9 has its back side supported and reinforced by the sufficiently solidified first sand mold 8. It is prevented from being deformed even when it is filled with sand, subjected to vibration, and pulled under reduced pressure, and is set in the sand mold 11 in the desired shape corresponding to the article to be cast. Thereafter, as shown in FIG. 1(f), the molten metal 12 is poured, and while melting the fugitive model 9, it replaces the fugitive model 9 and forms a shape corresponding to the fugitive model 9. A casting is produced. When pouring the molten metal 12, the pressure of the sand mold 11 may be reduced in order to remove gas generated by dissolving the fugitive model 9. In this case, the surface of the sand mold 11 is covered with an air-permeable lid member 13.
It is preferable to cover it with

In this example, first, a first sand mold 8 is formed using a support mold 2, and then the support mold 2 is replaced with a fugitive model 9, and when forming a second sand mold 10, this first sand mold While supporting and reinforcing the fugitive model 9 by 8, the second sand mold 10 is
This prevents the fugitive model 9 from being deformed even if it is subjected to non-uniform force when forming the sand mold. Also, the fugitive model 9 can be set in the sand mold in a desired shape corresponding to the article to be cast, and the cast article can be manufactured with high precision.

The present invention is not limited to the above-mentioned examples, but various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. Needless to say.

For example, in the embodiment described above, a support mold 2 is used in which a part having the same shape as that obtained by cutting the evanescent model in half along its axis is formed only on its - side.
A support mold 2 may be used in which a member having the same shape as the evanescent model is formed, a flat support member is attached to the member, and portions having shapes corresponding to the evanescent model are formed on both sides of the member. .

Effects of the Invention According to the present invention, it is possible to effectively prevent deformation of a fugitive model during sand mold formation and to manufacture a cast product with high precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the steps of an investment model casting method according to an embodiment of the present invention. ■... Casting flask, 2... Support mold, 3... Lid member, 4... Clamp, 5... Base,
6... Filling head, 7... Vibrator, 8... First sand mold, 9... Vanishing model, 10...
...Second sand mold, 11...Sand mold, 12...Molten metal,
13... Lid member.

Claims (1)

[Claims] In a fugitive model casting method in which a fugitive model is set in a sand mold, the fugitive model is melted and disappeared by molten metal, and a casting is cast, a flat plate having a part of the same shape as the fugitive model on at least one side A support mold is fixed in a casting flask at a position where the fugitive model is to be set, with the surface having the same shape as the fugitive model facing upward, and the inside of the flask divided into two by the support mold is fixed. The upper space is filled with sand, the flask and the support mold are inverted, the support mold is taken out, a fugitive model is set in the part from which the support mold was taken out, and the fugitive model is set in the other space in the flask. A vanishing model casting method characterized by filling sand and casting.