JPH09295103A - Core molding method and core molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new core molding method which can uniformly press- harden a green sand with easy means even in the case of core having complicate shape, and a device therefor. SOLUTION: Sand 12 enclosed in a core mold 11 is pressed onto the core mold 11 with a bag body 13 expanded by fluid pressure in the inner part so as to compress the sand 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding method and molding apparatus for a core used in casting.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, when molding a core with a molding sand, a core sand 52 is placed in a core mold 51.
The raw sand 52 is compressed and hardened inside the mold 51 by the pressing body 53 having a diameter slightly smaller than the upper opening of the core mold 51.

[0003]

However, in the case of molding a core having a simple shape such as a columnar shape, it is possible to press the green sand uniformly and sufficiently by the above-mentioned conventional technique. In the case of a core having a complicated shape having a portion (branch portion A in the example shown in FIG. 8) on which the compression force of the body 53 does not directly act, the portion where the green sand 52 is not sufficiently compressed (branch portion) A) occurs, and the core may collapse when the core is released from the mold.

As a molding method of a core having a complicated shape, a shell method and a bonding of foundry sand by a cold box method are known, but the shell method requires a heat treatment and a cold box method. The law is bad for the environment, such as using harmful gas. Therefore, it is an object of the present invention to provide a novel core molding method and apparatus capable of uniformly compacting green sand by an easy means even if the core has a complicated shape.

[0005]

Means for Solving the Problems In order to achieve the above object, the present invention has taken the following technical means. That is,
The present invention is characterized in that the sand contained in the core mold is pressed against the core mold by the bag body that expands due to the internal fluid pressure to compress the sand. Since the bag body can be mounted in a relatively free position in the core mold, by placing the bag body at a required position to surely compress the sand, even if the core body has a complicated shape. Molding can be done easily and surely with raw sand.

Further, according to the present invention, sand is put in the core mold, a long bag having rubber-like elasticity is embedded in the sand, and the bag is inflated by the internal fluid pressure, The bag is pressed against the core mold to compress the sand. In this way, if the bag body is made long, if the sand pressure is insufficient at one or several locations in the longitudinal direction due to the complexity of the shape of the core, the bag body will expand significantly at such locations. As a result, the sand can be reliably compressed at the required pressure.

Further, according to the present invention, the inside of the sand filled in the core mold is hollow, and the sand is pressed against the core mold by a bag body that expands from the inner surface of the sand by fluid pressure. Compress. By making the sand hollow like this, the pressing area of the bag is increased, a large total pressure can be obtained with less power, and the sand can be reliably pressed and solidified. Since the sand is pressed against the core mold from the inner surface, the sand can be uniformly compressed even in a complicated shape.

[0008] The above molding method comprises a core mold, a bag body mounted in the core mold, and a bag for pressing the sand contained in the core mold by the bag body against the core mold. It can be used by a core molding apparatus provided with a fluid supply means for pressurizing and filling a fluid inside the body.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. This core molding apparatus 10 molds a core of a required shape from green sand 12 (cast sand), and a core mold 11 and A bag body 13 mounted at a required position in the core mold 11 and a fluid supply means 14 for pressurizing and filling the bag body 13 with a fluid are provided.

The core mold 11 can be composed of a metal mold, a wooden mold, or the like. In the embodiment shown in FIG. 1, the central cylindrical portion 15
And a branch-shaped portion 16 protruding from the axially intermediate portion of the cylindrical portion 15 in a direction orthogonal to the axial direction. The outline setting surface of the core is indicated by a thick line in the figure. At the top of the core mold 11, sand 1 filled inside the mold
A gap 25 is formed so that the air inside the sand 16 escapes when the sand 6 is compressed.

The bag body 13 is made of a material having rubber-like elasticity and is elongated. As such a bag body 13, a rubber tube or an airtight elastic bag can be adopted. The bag body 13 is mounted in the core mold 11 so as to extend over substantially the entire axial length of the cylindrical portion of the core. Also,
It is preferable that the rubber-like elastic deformation is largely performed at a pressure lower than the pressure required to press and solidify the sand 12.

Further, in the present embodiment, the bag body 13 is arranged in the axial center portion of the core mold 11, and the raw sand 12 is blown around the bag body 13. The fluid supply means 14 is a means for pressurizing and filling a fluid such as a gas such as air or a liquid such as oil into the bag body 13. The fluid is supplied from a pump (not shown) at a required pressure. Tube 1
7 and a switching valve box 18 connected to the end of the supply pipe 17, and the bag body 13 is attached to the valve box 18.

The valve box 18 includes an inside of the supply pipe 17 and a bag body 13.
An operating lever 19 is provided which is switchable between a pressurizing position communicating with the inside and a degassing position communicating the outside air with the inside of the bag body 13. By operating the lever 19, the internal valve body is switched. It is configured to be operated. The fluid pressure supplied from the supply pipe 17 is 6 to 8 kg in this embodiment.
It is set to about / cm ^2, but it can be set to any pressure if necessary.

In order to mold a core with this core molding device 10, the operating lever 19 is set to the deaeration position, the bag 13 is mounted in the core mold 11, and By blowing (blowing) the same raw sand 12 as that used for the mold making, the bag body 13 is embedded in the sand 12 put in the core mold 11. Further, in this state, from another point of view, the inside of the sand 12 is made hollow so as to substantially penetrate the axial center of the cylindrical portion 15, and the bag body 13 is provided in this hollow portion. There is.

When the operation lever 19 is switched to the pressurizing position in such a state, the fluid such as oil or air supplied from the supply pipe 17 is pressurized and filled in the bag body 13, and the bag body 13 is inflated by the fluid pressure. Will be done. That is, the bag body 13
Due to the fluid pressure inside, the sand 12 acts to press the sand 12 against the core mold 11 with a uniform force from the inner surface of the hollow portion of the sand 12, and the raw sand 12 is pressed and solidified.

Further, even in a portion where the distance between the bag body 13 and the outer shape setting surface of the core mold 11 is relatively large before pressurization, that is, in the branch portion 16 in this embodiment, the bag body 13 is also provided. By virtue of the large elastic deformation of the corresponding portion of No. 3, the green sand 12 can be reliably and uniformly compressed. The thickness of the core can be controlled by pressing the raw sand 12 with the bag 13 in several times. Also, the bag 1
Vibration may be applied to the core mold 11 at the time of pressurization by 3.

After that, the operating lever 19 is switched to the deaeration position to contract the bag body 13, the bag body 13 is taken out from the molded core, and the core is released from the core mold 11.
As shown in FIG. 2, the core mold 11 is composed of a split mold composed of an upper mold 11a and a lower mold 11b, and a mold release air supply port 20 is provided in the lower mold to remove the core. It can be released easily and quickly without breaking.

According to the present embodiment, since the core is molded by pressing the raw sand and pressing it, gas is hardly generated, the environment is excellent, and the processing is simple, so that the productivity is improved. It is excellent, the manufacturing cost can be reduced, and the equipment cost can be reduced because the structure of the device is very simple. In addition, the bag body 13 prevents the sand 12 from forming not only in the columnar portion 15 but also in the branch portion 16.
Since it is possible to uniformly compress the core, it is possible to prevent molding defects of the core and prevent the core from collapsing during handling after molding.

Further, since the core molded according to this embodiment is hollow, it is inserted into the hollow portion of the core 21 as shown in FIG. 3 when the core is installed inside the mold. The rod 22 allows the core 21 to be handled without touching the surface of the core 21, and prevents the surface of the raw sand core having a low hardness and being easily broken. Note that FIG. 3 shows a state in which the core 21 is arranged inside the mold 23.

Further, since the raw sand is used, the apparatus 10 can be easily arranged in the vicinity of the molding machine of the mold, and the production line in the automatic molding equipment is facilitated. The present invention is not limited to the above embodiment, and the design can be changed as appropriate.

[0021]

As described above, according to the present invention,
Even with a simple structure, even in the case of molding a core having a complicated shape, the sand can be reliably compressed by the bag body, and it is possible to prevent molding failure and collapse of the core.
In particular, when molding a core with raw sand, the raw sand can be reliably compacted even in a complicated shape, and it is possible to reduce molding defects while improving environmental friendliness and cost reduction. .

[Brief description of drawings]

FIG. 1 shows a first embodiment of the present invention, a right view is a cross-sectional view showing a state before pressurizing the inside of a bag body, and a left view is a cross-sectional view showing a state after pressurization.

FIG. 2 is a cross-sectional view showing a mold releasing means.

FIG. 3 is a cross-sectional view showing a method of mounting the core on the mold.

FIG. 4 is a cross-sectional view showing a conventional technique.

[Explanation of symbols]

 10 Core Molding Equipment 11 Core Mold 12 Sand (Natural Sand) 13 Bag Body 14 Fluid Addition Means

Claims (6)

[Claims] 1. Sand (1) contained in a core mold (11)
2) is pressed against the core mold (11) by the bag body (13) that expands due to the internal fluid pressure, so that the sand (12)
A core molding method characterized by compressing. 2. A bag body in which sand (12) is placed in a core mold (11) and a long bag (13) made of a material having rubber-like elasticity is embedded in the sand (12). (1
A core molding method characterized in that the sand (12) is compressed by inflating 3) by fluid pressure and pressing the sand (12) against the core mold (11) by the bag body (13). . 3. Sand (1) contained in a core mold (11)
The inside of 2) is made hollow, and the sand (12) is pressed against the core mold (11) by the bag body (13) which expands from the inner surface of the hollow part of the sand (12) by fluid pressure.
A core molding method characterized by compressing. 4. A core mold (11), a bag body (13) mounted in the core mold (11), and a bag body (13) for containing the core mold (11). Sand (12) to the core type (1
1) A core molding apparatus comprising: a fluid supply means (14) for pressurizing and filling a fluid into the bag body (13) so as to press it against 1). 5. The core molding apparatus according to claim 4, wherein the bag body (13) has an elongated shape. 6. The core molding apparatus according to claim 4, wherein the bag body (13) is made of a material having rubber-like elasticity.