JPH04305331A - Production of lost foam pattern - Google Patents

Abstract

PURPOSE:To provide a process for producing a lost foam pattern which can easily produce even in the lost foam pattern having intricate shapes without dividing the pattern. CONSTITUTION:This method produces a lost foam pattern having a hollow part 11 of a prescribed shape by first molding a film-like core 1 consisting of an foam able material having the hollow part of the prescribed shape, then disposing this core into an expansion molding mold 9 having the hollow part of the prescribed shape, packing foamable beads between the hollow part of the expansion molding mold and the core and expanding these beads. The deformation of the core 1 is preferably prevented by supplying fluid of a prescribed pressure to the inner side of the core 1 at the time of packing the foamable beads between the hollow part 1 of the expansion molding mold 9 and the core 1 and expanding the beads at this time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a disappearing model, and more particularly to a method that allows even complex shapes to be easily manufactured without dividing the model.

0002

2. Description of the Related Art One of the casting methods uses a so-called vanishing model. This disappearing model is made of, for example, styrofoam and has the same shape as the product to be cast. Such a disappearing model is placed in a mold, its surroundings are filled with molding sand, and the metal is poured into it. As a result, the disappearing model melts and disappears, hot water enters the melted area, and a product with the same shape as the disappearing model is cast.

0003

[Problems to be Solved by the Invention] According to the above-mentioned conventional structure, there are the following problems when manufacturing a disappearing model. For example, assume a simple-shaped vanishing model 101 as shown in FIGS. 14 and 15. In this case, the hollow part 103 that extends straight is provided, and therefore, by using a slide core of a mold, etc., the disappearing model 101 having such a hollow part 103 can be easily manufactured. be able to.

On the other hand, in the case of the vanishing model 105 shown in FIGS. 16 and 17, the hollow part 107 is bent, so the simple method using the slide core of the mold described above, etc. cannot be manufactured. Therefore, the disappearance model 1
05 is divided into two parts, manufactured separately, and then glued together using an adhesive.

However, when such an adhesive is used, the amount of adhesive becomes a problem; for example, too much adhesive may protrude from the adhesive surface. The parts that protrude to the outside of the lost model can be scraped off, but the parts that protrude to the inside cannot be scraped off easily, and if cast as is, defects will occur in the product. It turns out. On the other hand, if the amount of adhesive is too small, gaps will be created on the adhesive surface, resulting in more serious product defects.

There is also a method of manufacturing a vanishing model using a shell or a core made of cold sand. This case will be explained with reference to FIGS. 18 to 26. First, as shown in FIG. 18, using a core mold 111, a core made of shell or cold sand as shown in FIG. 10
Mold 9. Next, as shown in FIGS. 20 and 21,
Using the vanishing model 115 and the core 109, an integral body of the vanishing model 119 made of foamed resin and the core 109 is molded (as shown in FIG. 21).

Next, as shown in FIG. 22, a runner sprue 121 is glued and fixed to the above-mentioned vanishing model 119 and core 109 integrated together. Then, as shown in FIG. 23, a coating mold 123 is applied, and as shown in FIG.
4, it is placed in a casting flask 127 and its surroundings are filled with molding sand 125. After that, pour hot water into it and see Figure 2.
A casting 129 as shown in 5 is manufactured. Then, unnecessary parts such as the runner sprue 121 are removed, and the core 109 is removed, resulting in a product 13 as shown in FIG.
Get 1.

[0008] In the case of the method using the core 109 as described above, there is a problem that the core 109 must be finally destroyed and removed. In addition, the specific gravity of the core 109 is 1.4 to 1.6, which is larger than that of the vanishing model 119 (0.020 to 0.0 in the case of the vanishing model 119).
25), which makes handling difficult and costly. Specifically, a part of the disappearing model may break. Furthermore, as shown in FIG. 23, in the process of applying the coating mold 123, the core 109 absorbs moisture from the coating mold 123, and it takes time to remove it, and if it is not removed sufficiently, it will cause serious casting defects. There was also the problem that it caused

[0009] The present invention has been made based on the above points, and its purpose is to provide a vanishing model that can be easily manufactured without dividing it, even for a vanishing model with a complicated shape. The purpose is to provide a manufacturing method.

0010

[Means for Solving the Problems] In order to achieve the above object, a method for manufacturing a vanishing model according to the present invention involves molding a film-like core made of a fugitive material and having a hollow portion of a predetermined shape, and A vanishing model with a hollow part of a predetermined shape is created by placing foam beads in a foam mold having a hollow part of a predetermined shape and filling and foaming between the hollow part of the foam mold and the core. It is characterized in that it is manufactured. At that time, when foam beads are filled between the hollow part of the foam mold and the core and foamed, fluid at a predetermined pressure is supplied to the inside of the core to prevent the core from deforming. is preferred.

[0011]

[Operation] First, a film-like core made of a fugitive material and having a hollow portion of a predetermined shape is molded using a molding machine. Next, the above-mentioned core is placed in a foaming mold having a hollow part of a predetermined shape, and foam beads are filled between the hollow part of the foaming mold and the core and foamed to form the predetermined hollow part. Manufacture a vanishing model with At that time, the foamed resin part and the core are joined to form a disappearing model. In this way, by using a core made of a fugitive material, it has become possible to easily manufacture a fugitive model with a complicated shape without having to divide it into multiple parts. In addition, when foam beads are filled between the hollow part of the foam mold and the core and foamed, fluid at a predetermined pressure is supplied to the inside of the core to prevent the core from deforming. In this case, it is effective to prevent deformation of the core and obtain a disappearing model with a predetermined shape.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. 1 to 10. First, a core (shown in FIG. 2) 1 for producing a disappearing model is molded. This core 1 is
It is made of a fugitive material (eg, polyethylene, polypropylene, etc.) and is hollow. When molding this core 1, a fugitive material is placed in a blow molding mold 3 as a core mold shown in FIG. Inside the blow molding die 3, a hollow portion 7 of a predetermined shape is provided.
is formed, therefore, the fugitive material is in the hollow part 7.
It is molded into a thin film along the shape of. The inner surface of the core 1 is formed into a predetermined shape of the inner surface of the product casting.

Next, the molded core 1 is taken out from the blow mold 3. Then, a vanishing model is manufactured using the core 1 taken out and a foam mold 9 shown in FIG. 3. A hollow portion 11 having a predetermined shape is formed in the foaming mold 9 . The above-mentioned core 1 is placed inside this hollow part 11.
Place. At this time, the core 1 is reinforced using a reinforcing member (not shown) if necessary. Note that, like the core 1, the reinforcing member is also molded from a fugitive material.

Next, foamed beads are filled into the hollow part 11 through the blowing port 15, and the temperature is increased to 120°C, for example.
Steam of about 1.2 kg/cm 2 is blown into the foam beads to form a vanishing model 17 (shown in FIG. 4). At that time, in order to control the deformation of the core 1, the inside of the core 1 is loaded with a weight of 1.2 kg/cm, for example, according to the pressure of the steam.
2. Supply fluids such as water, air, oil, etc. at a pressure of about 2. Also, when molding the disappearing model 17, the foamed resin part and the core 1 are in a state of being joined, so that the 1
This results in constructing the vanishing model 17.

After manufacturing the vanishing model 17, it is taken out from the foaming mold 9, and the protruding portion of the core 1 is removed, as shown in FIG. 4, to form a state as shown in FIG. Then, as shown in FIG. 6, the runner gate 18 is bonded and fixed. Next, as shown in FIG. 7, a coating mold 20 is applied to the surface. Then, as shown in FIG. 8, it is placed in a mold 19, the surrounding area is filled with molding sand 21, and casting is performed. That is, when pouring hot water through the runner sprue 18, the disappearing model 17 gradually melts and disappears, and the hot water enters that part. As a result, a casting 22 as shown in FIG. 9 is cast. After that, unnecessary parts such as the runner sprue 18 and the like are removed to obtain a product 25 as shown in FIG. 10.

According to this embodiment, the following effects can be achieved. First, the disappearing model 1 has a complicated shape.
7 can also be easily manufactured without being divided. This is because the core 1 made of a fugitive material is used, and it is sufficient to form the core 1 into a predetermined shape. Therefore, there is no need to use adhesive, which was a concern when conventionally divided.
Problems such as product defects can be resolved. In particular, since the problem of adhesive extrusion is eliminated, it can be sufficiently applied to engine exhaust manifolds, intake manifolds, etc.

Unlike the conventional core made of shell or cold sand, the core 1 is hollow and extremely lightweight, so it is easy to handle, especially when it is removed after the disappearance model 17 is manufactured. There was no need for it, and the work was greatly simplified. Further, since the material cost is low, it is possible to reduce the cost.

A coating mold 18 can be applied to the surface of the produced disappearing model 17 in the same manner as in the case of a normal disappearing model. Therefore, the smooth inner surface,
You can get the exterior.

Next, referring to FIGS. 11 to 13, the second
An example will be explained. In the case of the first embodiment, the blow molding die 3 was used as the core mold, but in the case of this embodiment, a vacuum molding die 30 is used. That is, FIG.
Films 31 and 33 are placed in the core mold 3 shown in FIG. In this state, as shown in FIG. 13, the films 31 and 33 are deformed along the shape of the hollow part of the core 3 by evacuation, thereby obtaining the core 1.

It should be noted that the present invention is not limited to the above embodiments. First, the thickness of the core 1 is not particularly limited. Further, whether or not to use a reinforcing member is also optional depending on the thickness of the core 1. or,
In each of the above embodiments, the present invention is applied to manufacturing a vanishing model with a complicated shape, but it is of course applicable to manufacturing a vanishing model with a simple shape. moreover,
In addition to the blow molding machine and vacuum molding machine described above, the core may be molded using an injection molding machine or the like.

[0021]

Effects of the Invention As detailed above, according to the method for manufacturing a vanishing model according to the present invention, a hollow core made of a vanishing material is used to manufacture a vanishing model. The model can also be easily manufactured without dividing it. Therefore, there is no need to use an adhesive, which eliminates the problems caused by using an adhesive, and the core is lightweight and inexpensive, and it is easy to handle as there is no need to take out the core.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, and is a sectional view of a core mold.

FIG. 2 is a diagram showing a first embodiment of the present invention, and is a sectional view of a core.

FIG. 3 is a diagram showing a first embodiment of the present invention, and is a sectional view showing how a disappearing model is manufactured by a foam molding machine.

FIG. 4 is a sectional view of a vanishing model manufactured in a diagram showing the first embodiment of the present invention.

FIG. 5 is a sectional view of a vanishing model manufactured in a diagram showing the first embodiment of the present invention.

FIG. 6 is a diagram showing a first embodiment of the present invention, and is a sectional view showing a state in which a runner sprue is bonded and fixed to a disappearing model.

FIG. 7 is a cross-sectional view showing a state in which a coating mold is applied in a diagram showing the first embodiment of the present invention.

FIG. 8 is a diagram showing the first embodiment of the present invention, and is a sectional view showing the state of casting.

FIG. 9 is a sectional view showing a cast product according to a first embodiment of the present invention.

FIG. 10 is a sectional view showing a cast product according to a first embodiment of the present invention.

FIG. 11 is a diagram showing a second embodiment of the present invention, and is a sectional view of a core mold.

FIG. 12 is a diagram showing a second embodiment of the present invention, and is a sectional view showing how the core is manufactured.

FIG. 13 is a diagram showing a second embodiment of the present invention, and is a cross-sectional view showing how the core is manufactured.

FIG. 14 is a front view of a vanishing model, showing a conventional example.

FIG. 15 is a diagram showing a conventional example, and is a sectional view of a disappearing model.

FIG. 16 is a diagram showing a conventional example, and is a front view of a disappearing model.

FIG. 17 is a diagram showing a conventional example and is a sectional view of a disappearing model.

FIG. 18 is a cross-sectional view of a core mold, showing a conventional example.

FIG. 19 is a cross-sectional view of a core, showing a conventional example.

FIG. 20 is a diagram showing a conventional example and is a sectional view of a disappearing model.

FIG. 21 is a cross-sectional view showing a disappearing model in a diagram showing a conventional example.

FIG. 22 is a cross-sectional view showing how a runner sprue is bonded and fixed to a vanishing model in a diagram showing a conventional example.

FIG. 23 is a cross-sectional view showing how a coating mold is applied in a conventional example.

FIG. 24 is a cross-sectional view showing the state of casting in a conventional example.

FIG. 25 is a sectional view of a cast product showing a conventional example.

FIG. 26 is a sectional view of a cast product in a diagram showing a conventional example.

[Explanation of symbols]

1 Core 3 Blow molding mold (core mold) 7 Hollow part of blow molding mold 9 Foaming mold 11 Hollow part of foam mold 17 Disappearance model

Claims (2)

[Claims] Claim 1: A film-like core made of a fugitive material having a hollow part of a predetermined shape is molded, and the core is placed in a foam mold having a hollow part of a predetermined shape to form a foam mold. A method for manufacturing a vanishing model, characterized in that a vanishing model having a hollow part of a predetermined shape is manufactured by filling and foaming foam beads between the hollow part and a core. 2. In the vanishing model manufacturing method according to claim 1, when foaming beads are filled between the hollow part of the foaming mold and the core to cause foaming, a fluid at a predetermined pressure is applied to the inside of the core. A method for producing a disappearing model, characterized in that deformation of the core is prevented by supplying the core.