JPH0763801B2 - Casting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a casting method using a sand mold made of foundry sand,
In particular, the present invention relates to a method for manufacturing a casting having an attached protrusion protruding from the casting body.

(Prior art) Projections such as hanging projections (hanging tengu), which are used to lift cast castings with cranes, and blind risers to prevent shrinkage cavities during casting. The following casting method has been adopted to cast the attached protrusion.

A method of molding with a molding sand together with a casting body by using a wooden mold or a mold.

A method of using a molded product of a resin foam, such as Styrofoam, and removing the foam by molding after molding, or by pouring the molten metal as it is without molding.

(Problems to be Solved by the Invention) In the above method, it is necessary to remove the mold after molding,
It requires coating work on the mold surface, which requires man-hours.

The former of the above methods has the same problem as the work such as removing the foamed body after molding is required. The latter of the above methods has a small number of steps, but has a problem that a toxic gas is generated when the resin foam is melted, and a casting defect is likely to occur.

Therefore, an object of the present invention is to solve the above problems,
It is an object of the present invention to provide a casting method which is inexpensive and requires a small number of man-hours and can cast an auxiliary protrusion having a desired shape without causing a casting defect.

[Structure of the Invention] (Means for Solving the Problems) The present invention developed to achieve the above-mentioned object includes a main body mold having a shape corresponding to a casting main body portion, and an auxiliary protrusion protruding from the casting main body portion. Combined with a ceramic mold having a hollow shape having a corresponding inner surface shape and having an opening leading to the casting main body at one end, and filling the molding sand around the main mold and the ceramic mold, the main mold A mold having an internal space consisting of the mold removal part of the main body mold and the interior of the ceramic mold is formed by removing only the mold, and the molten metal is solidified by supplying hot water into the internal space of the mold, and then the mold is separated. The casting method is characterized by including the steps of taking out the cast product by performing the above step, and then breaking and removing the ceramic mold covering the attached protrusion.

(Operation) The casting main body is cast using the main body mold and the molding sand as in the conventional method. The attached protrusion protruding from the casting main body is cast integrally with the casting main body using the ceramic mold. That is, by leaving this ceramic mold embedded in the molding sand that constitutes the mold of the casting body, the inner surface of the ceramic mold forms the mold surface of the accessory protrusion. For this reason, it is not necessary to perform die-cutting and painting on the attached protrusion. In addition, the ceramic mold does not generate harmful gas even when it comes into contact with molten metal, hardly generates other gas, and does not cause seizure because it has sufficient fire resistance. No casting defect is caused in the cast part and the cast body part. Further, the ceramic mold can be obtained in a desired shape at a relatively low cost, and can be easily removed by splitting it with a hammer after casting.

(Embodiment) An embodiment of the method of the present invention will be described below with reference to Figs.
It will be described with reference to the drawings. Ceramic mold 10 used in this embodiment,
It is used to cast the hanging projections for lifting the cast casting body with a crane. The ceramic mold 10 is preferably made of unglazed ceramic, and its shape is hollow as shown in FIG. The wall thickness t of the mold wall of the ceramic mold 10 is 1 to several mm, preferably 2 to 3 mm, and an opening 11 is provided at the lower end of the drawing as shown in FIG. A flat spherical head 13 is provided on the upper side of the cylindrical body 12 in the figure. A small hole 14 for degassing is formed in the center of the head 13.

The edge 15 on the opening 11 side of the body portion 12 is formed in a flare shape that spreads outward. The inner surface 16 of the porcelain mold 10 corresponds to the shape of the accessory projection to be cast.

Next, an example of the casting method of the present invention using the ceramic mold 10 will be described. As shown in FIG. 3, the open end edge 15 of the ceramic mold 10 is pressed to a predetermined position of the main body mold 20 such as a wooden mold for molding the casting main body, that is, a position where the attached protrusion is provided, and the main body mold 20 and The outer periphery of the ceramic mold 10 is filled with molding sand 30. After that, the main body mold 20 is removed in the same manner as a normal molding operation, but the ceramic mold 10 is left as it is in the mold with the molding sand 30. The mold surface 30a of the molding sand 30 molded by the main body mold 20 is coated with the mold coating agent, but the inner surface of the ceramic mold 10 is not coated with the mold coating agent and is left as it is. Thus the ceramic mold
When a mold is created with 10 and foundry sand 30 and hot water is supplied, the ceramic mold is formed at the same time as the inside of the mold formed by the main mold 20.
Molten metal also flows into the interior of the casting 10, and the attached protrusion of the ceramic mold 10 is cast together with the casting body.

The ceramic mold 10 has a small hole 14 shown at the top of the head 13 and a maximum diameter part of the head 13 so that the molten metal can be more completely filled by facilitating degassing at the time of hot water supply. It is desirable to provide a plurality of small holes (not shown) in the horizontal direction so that the ceramic mold 10 can be used in either the vertical or horizontal direction. When used in a horizontal orientation, the small hole 14 is not always necessary because there is a large opening 11 communicating with the casting body.

In addition, since the ceramic mold 10 has sufficient fire resistance, there is no risk of causing problems such as seizure without applying a coating agent to the inner surface of the ceramic mold 10, and a tool such as a hammer can be used when releasing the mold. It can be easily removed by tapping. And this ceramic mold 10 does not generate toxic gas,
Almost no other gas is generated, and there is no adverse effect such as causing casting defects in the cast body as well as the auxiliary projection.

FIG. 4 shows another example of a ceramic mold used in the method of the present invention. In this illustrated example, a ceramic mold 10a for blind hot water
The molding state of is shown. This ceramic mold 10a has a shape in which an ellipse is rotated about its major axis, has an opening 11a communicating with the casting body at one end side, and has a protrusion protruding to the inner surface side at the other end side. There is part 18. The material, wall thickness and the like of this ceramic mold 10a may be the same as those of the ceramic mold 10 of the above-mentioned embodiment. The casting method using this ceramic mold 10a is the same as in the above-mentioned embodiment. Reference numeral 20a indicates a wooden mold for molding the cast body.

[Effects of the Invention] As described above, according to the method of the present invention, the number of man-hours required for molding for forming the protrusions for lifting and auxiliary protrusions such as blind risers is reduced. And the shape of the attached protrusion is standardized (standardized)
Ceramic molds can be obtained at low cost even if they have a relatively complicated shape if possible, so that casting costs can be reduced, and casting defects and poisonous gas are generated in the accessory protrusion and the casting body. Nor. Further, since the above-mentioned ceramic mold can be easily beaten with a hammer or the like, there is an effect that the mold can be easily removed after casting.

[Brief description of drawings]

1 is a perspective view showing an example of a ceramic mold used in the method of the present invention, FIG. 2 is a perspective view in which a part of the ceramic mold shown in FIG. 1 is cut away, and FIG. 3 is FIG. FIG. 4 is a partial sectional view showing a molding state using the ceramic mold shown in FIG. 4, and FIG. 4 is a partial sectional view showing a modified example of the ceramic mold used in another embodiment of the present invention. 10,10a …… Ceramic mold, 11,11a …… Opening, 20,20a …… Main body for molding, 30 …… Moulding sand (mold).

Claims (2)

[Claims] 1. A main body die having a shape corresponding to a casting main body portion, and a hollow shape having an inner surface shape corresponding to an auxiliary protrusion protruding from the casting main body portion, and an opening communicating with the casting main body portion at one end. After combining the main body mold and the ceramic mold with molding sand, the interior of the main mold and the interior of the main mold by removing only the main mold. A mold having a space is formed, and after the molten metal is solidified by supplying hot water into the internal space of the mold, the mold is removed to take out the cast product, and the ceramic mold covering the attached protrusion is further removed. A casting method comprising the step of cracking and removing. 2. The casting method according to claim 1, wherein the ceramic mold is a unglazed ceramic mold.