JP3332206B2 - Aging method for foundry sand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aging molding sand in which water is added to molding sand in a container, and then the molding sand is impregnated with water to exert an aging effect in a short time.

[0002]

2. Description of the Related Art The conventional maturation of foundry sand means that the active clay component is heated to 400 ° C or more due to the heat of molten metal and becomes inactive fine powder. It is said that by giving the inert fine powder which has received only the heat of 1 hour or more a standing time until the water is added to the inert fine powder to infiltrate the inert fine powder, it is restored to the active clay content again. Therefore, in the industry, the maturation of this foundry sand,
He sleeps and rests all night and regains vitality. That is, for aging of the foundry sand according to the prior art, a sand storage tank for storing the foundry sand for one hour or more is essential.

[0003]

The aging effect of foundry sand is as follows.
It is proportional to the standing time of the casting sand after water addition, and the longer the standing time, the greater the effect. However, a longer sand storage tank requires a large sand storage tank.
Since only a leaving time of less than the time is required, the molding sand is insufficiently matured. The present invention provides a method for aging a molding sand which shortens the standing time after water addition, makes the sand storage layer unnecessary, and sufficiently exerts the aging effect of the molding sand, and further contributes to resource saving of the binder. The purpose is to provide.

[0004]

The above objects can be attained by the following casting sand processing method. That is, molding sand is sealed in a sealable container, and the molding sand in the container is kept in a depressurized state, water is added, and the water adheres to the surface of the fish egg-like inert fine powder layer of the sand particles. Thereafter, a molding sand ripening method in which moisture is permeated in a short time to a deep portion of the fish egg-like inert fine powder layer by a differential pressure between the atmospheric pressure and the decompression force. According to the method for maturation of the foundry sand, the maturation effect can be sufficiently obtained in a short time.

[0005]

Embodiments of the present invention will be described below in detail. FIG. 1 is a conceptual sectional view of the foundry sand according to the present invention. The foundry sand to be used for casting is usually covered with a fish egg-like inert fine powder layer 2 on the outer surface of sand particles 1. The fish egg-shaped inert fine powder layer 2 is formed by changing the active clay component into a soft porous ceramic shape due to the thermal effect of the molten metal. Whether or not the moisture has evenly penetrated into the porous layer up to the deep part 4 of the active fine powder layer 2 has a great effect on the aging of the casting sand and thus on the properties of the casting sand. Layer 2
It takes a long time of one hour or more to replace the air in the porous portion with the water that permeates. The present invention can greatly reduce the permeation time of water in the porous portion of the fish egg-shaped inert fine powder layer 2 of the foundry sand by using the differential pressure between the atmospheric pressure and the depressurizing force, and can reduce the sand storage layer. Make it unnecessary. In addition, since the aging effect of the foundry sand can be sufficiently exhibited, it contributes to resource saving by reducing the amount of active clay added.

[0006]

FIG. 2 shows an embodiment of the present invention. A casting sand inlet 7 provided with a casting sand inlet opening / closing valve 6 capable of holding the depressurizing force in the container 5 is provided at one upper end of the sealable container 5. Below the other end, there is provided a molding sand discharge port 9 provided with a molding sand discharge side opening / closing valve 8 which can also hold the reduced pressure in the container 5. Furthermore,
In order to stir the casting sand injected from the casting sand inlet 7 into the container 5 and to move the casting sand toward the casting sand discharge port 13 side, the casting sand stirring and moving directly connected to the spiral blade drive source 10 for rotating the spiral blade forward and reverse. A spiral blade 11 is provided. In addition, a pipe 12A directly connected to a decompressor 12 for depressurizing the inside of the container 5 is connected to a position (upper part) not close to the casting sand in the container 5, and further, the inside of the container 5 is reduced separately from the pipe 12A. A pipe 13A connected to an atmosphere release valve 13 capable of holding the pressure and opening the inside of the container 5 to the atmosphere for introducing atmospheric pressure is provided. The container 5 is provided with a water adding device 14 for evenly adding water to the foundry sand during depressurization.

The operation will be described below. First, a predetermined amount of molding sand is charged into the sealed container 5. This casting is performed by opening a casting sand inlet side opening / closing valve 8 below the casting sand inlet 7 and then rotating the molding blade stirring drive rotary screw 11 driven by the spiral blade drive source 10 to cast the casting in the container 5. The sand is stirred and moved to the casting sand discharge port 9 side. After a predetermined amount of foundry sand is charged, the on-off valve 6 on the foundry sand input side is closed.
Next, the inside of the container 5 is set to have a set pressure within a range from 500 hPa at a boiling point of about 80 ° C. to 50 hPa at a boiling point of about 30 ° C.
The pressure is reduced by the pressure reducer 12 connected to the inside of the container 5.

After the inside of the container 5 reaches the set decompression force, the decompression device 1
2 holds the set pressure reduction force. In this state, a predetermined water content of 3% to 8% is sprinkled and added to the foundry sand from the water adding device 14. This water content is larger than the water content of normal foundry sand. This is because the reduced pressure facilitates the evaporation of water. At this time, in order to uniformly add water to the molding sand, the spiral blade drive source is rotated forward and backward. After adding water to the casting sand,
The depressurization from the pressure reducer 12 is stopped, the atmosphere release valve 13 connected to the inside of the container 5 is opened, and the atmosphere is introduced, and the pressure inside the container 5 is set to the atmospheric pressure of 1013 hPa. The pressurization time due to the introduction of the air greatly affects the maturation effect of the foundry sand, that is, the permeation of moisture. When the pressure rise time by introduction into the atmosphere is shorter than 1000 hPa / sec, the molding sand tends to be solidified by the shock wave. In addition, when the pressure rise time is longer than 50 hPa / sec, the water permeability is inferior, and no practical aging effect is obtained. In this embodiment, the continuous sand mixer has been described.
A batch processing sand mixer can be used as a sealable container.

[0009]

As is apparent from the above description, the present invention effectively uses the pressure difference between the depressurizing force and the atmospheric pressure to ripen the foundry sand, that is, to infiltrate the water in a short time. This is a molding sand aging technology that enables the processing of foundry sand and reduces the amount of binder, that is, greatly contributes to resource saving.

[Brief description of the drawings]

FIG. 1 is a conceptual sectional view of a casting sand particle according to the present invention.

FIG. 2 is a conceptual diagram of a main part showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sand particle 2 Fish egg-shaped inert fine powder layer 3 Surface of fish egg-shaped inert fine powder layer 4 Deep part of fish egg-shaped inert fine powder layer, that is, particle surface 5 Container 12 Pressure reducer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B22C 5/00-9/00

Claims (4)

(57) [Claims] 1. A molding sand is sealed in a sealable container 5,
The pressure in the container 5 is reduced from 500 hPa to 50 hPa by the pressure reducer 12.
In a state where the pressure was reduced to a predetermined pressure, a predetermined amount of water was added to the surface 3 of the fish egg-shaped inert fine powder layer 2 covering the surface 4 of the foundry sand particles in a range of 3% to 8% by weight of the foundry sand. After 1000hP
Casting characterized by allowing water to penetrate to the deep part 4 of the fish egg-like inert fine powder layer 2 of the sand particles 1 by setting the pressure to 1013 hPa, that is, the atmospheric pressure, at an arbitrary pressure rising time between a / sec and 50 hPa / sec. Aging method of sand. 2. The inside of the container 5 is opened to the atmosphere to reduce the atmospheric pressure to the surface 3 of the fish egg-like inert fine powder layer of the sand particles 1.
The method of claim 1, wherein the sand is aged. 3. The casting according to claim 1, wherein the molten casting sand is discharged into the atmosphere to apply atmospheric pressure to the surface 3 of the fish egg-like inert fine powder layer of the sand particles 1. Aging method of sand. 4. The molding sand according to claim 1, wherein a continuous sand mixer or a batch processing sand mixer is used as the sealable container. Aging method.