JPH0569622B2 - - Google Patents

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention relates to a ceramic mold for forming an accessory projection provided on a casting body manufactured by a sand mold. .

(Prior art) Hanging protrusions (tsuri tengu) used to lift castings cast by sand molds with cranes, etc.
In order to cast an accessory protrusion that protrudes from the casting body, such as a blind riser for preventing shrinkage cavities during casting, the following forming means has been adopted.

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

A method in which a molded product of a resin foam such as Styrofoam is used, and the foam is removed from the mold after molding, or melted and removed by pouring molten metal into the mold without cutting out the foam.

(Problems to be Solved by the Invention) The above method requires cutting out the mold after molding, and also requires a mold coating operation on the mold surface, which takes a lot of man-hours.

The former method has the same problem as that of requiring work such as removing the foam from the mold after molding. The latter method requires fewer man-hours, but has problems such as generating toxic gas when the resin foam melts and being prone to casting defects.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a mold that can cast an attached protrusion of a desired shape at low cost, with a small number of man-hours, and without causing casting defects. be.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a hollow ceramic mold for casting an attached protrusion of a casting manufactured by a sand mold. In addition, it has an opening communicating with the casting body on one end side, an inner surface corresponding to the shape of the attached protrusion, and a wall thickness that allows it to be crushed relatively easily, so that it can be crushed after casting. To provide a ceramic mold for forming an attached protrusion, which is formed to be removable from the surface of a casting. This mold is preferably unglazed, and its thickness is, for example, 1 to several mm.

(Function) The ceramic mold having the above structure is attached to the main body for molding the casting main body and is buried together with the main body in foundry sand. After filling the outer periphery of this ceramic mold with foundry sand, the main body is removed from the mold, but the ceramic mold remains in the foundry sand. Thereafter, casting is performed by supplying hot water into the casting body and the inside of the ceramic mold, and when the mold is taken apart after casting, the molding sand is broken and removed by breaking the ceramic mold with a hammer or the like.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 3. Ceramic mold 1 of this example
0 is used to cast a lifting protrusion for lifting the cast body with a crane or the like.
This ceramic mold 10 is preferably made of unglazed ceramic;
Its shape is hollow as shown in FIG. The thickness t of the mold wall is 1 to several mm, preferably 2 to 3 mm, and an opening 11 is provided at the lower end as shown in FIG. An oblate spherical head 13 is provided on the upper side of the cylindrical body 12 in the drawing. A small hole 14 for venting gas is provided in the center of the head 13.

An end edge 15 of the body portion 12 on the opening 11 side is formed into a flared shape that spreads outward. The inner surface 16 of the ceramic mold 10 is adapted to the shape of the accessory projection to be cast.

Next, how to use this ceramic mold 10 will be explained. As shown in FIG. 3, the opening edge 15 of the ceramic mold 10 is pressed against a predetermined position of the main body 20 such as a wooden mold for molding the casting main body, that is, the position where the attached protrusion is to be provided, and the main body 20 and The outer periphery of the ceramic mold 10 is filled with molding sand 30. Thereafter, the main body mold 20 is demolded in the same manner as in a normal molding operation, but the ceramic mold 10 is left as it is in the mold made of foundry sand 30. A mold coating agent is applied to the mold surface 30a made of foundry sand 30 formed by the main body 20, but the mold coating agent is not applied to the inner surface of the ceramic mold 10 and is left as it is. When a mold is thus created using the ceramic mold 10 and the foundry sand 30 and hot water is supplied, the inside of the mold formed by the main body 20 is simultaneously filled with the ceramic mold 1.
The molten metal also flows into the inside of the mold 0, and the attached protrusion is cast by the ceramic mold 10 together with the casting body.

The ceramic mold 10 has a head part 1 to facilitate degassing during hot water supply and to more completely fill the molten metal.
The illustrated small hole 14 located at the top of the mold 3 and a plurality of small holes (not shown) are provided horizontally in the maximum diameter part of the head 13, so that the ceramic mold 10 can be used in either vertical or horizontal orientation. It is desirable to do so. In addition,
When used horizontally, the small hole 14 is not necessarily required since there is a large opening 11 communicating with the cast body.

Furthermore, if the ceramic mold 10 is used, there is no risk of problems such as seizure even if a mold coating agent is not applied to the inner surface, and moreover, it can be easily removed by hitting with a tool such as a hammer when breaking the mold. I can do it. This ceramic mold 10 does not emit toxic gases, and almost no other gases are emitted.
There is no adverse effect such as casting defects on the main body of the casting as well as on the attached protrusion.

FIG. 4 shows a second embodiment of the present invention, in which a ceramic mold 10a for a blind feeder is shown in a molded state. This ceramic mold 10a has a roughly elliptical spherical shape,
One end side has an opening 11a communicating with the cast body, and the other end side has a convex portion 18 projecting toward the inner surface. The material, wall thickness, etc. of this ceramic mold 10a may be the same as those of the ceramic mold 10 of the above-described embodiment. The method of use is also as described above. 20a is a wooden mold for molding the casting body.

[Effects of the Invention] As described above, according to the present invention, the number of man-hours required for molding work for molding an accessory projection such as a lifting projection or a blind feeder is reduced. Furthermore, if the shape of the attached protrusion can be standardized (standardized), ceramic molds can be obtained at low cost even if the shape is relatively complex, so casting costs can be reduced, and the attached protrusion and the cast body No casting defects or harmful gases are generated. Furthermore, since the ceramic mold is formed to have a wall thickness that can be easily broken with a hammer or the like, the mold can be easily removed after casting.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a ceramic mold showing an embodiment of the present invention, Fig. 2 is a partially cutaway perspective view of the ceramic mold shown in Fig. 1, and Fig. 3 is a perspective view of a ceramic mold shown in Fig. 1. FIG. 4 is a partial sectional view showing the shape of a ceramic mold according to another embodiment of the present invention. 10, 10a... Ceramic mold, 11, 11a... Opening, 20, 20a... Main body type for molding, 30... Casting sand (mold).

Claims (1)

[Scope of Claims] 1. A ceramic mold for casting an accessory protrusion of a casting manufactured by a sand mold, which is hollow and has an opening communicating with the main body of the casting on one end side, and has an opening communicating with the main body of the casting, and has an opening communicating with the main body of the casting. A casting characterized by having an inner surface that corresponds to the shape of the part, and having a wall thickness that allows it to be broken relatively easily, and which can be removed from the surface of the casting by being crushed after casting. A ceramic mold for forming the attached protrusion. 2. A ceramic mold for forming an attached protrusion of a casting according to claim 1, which has a small hole for degassing at a position different from the opening.