Method for regenerating casting sand

Abstract

Provided is a method for regenerating foundry sand capable of suppressing a decrease in the strength of a core after remanufacturing. A method for regenerating casting sand according to the present invention comprises: a preparation step for preparing casting sand to which a binder is adhered; a cleaning step for cleaning the casting sand prepared in the preparation step; a grinding step for grinding the casting sand cleaned in the cleaning step; and a rinsing step for rinsing the foundry sand that has been ground in the grinding step.

Description

Technical Field

[0001] This invention relates to a method for regenerating foundry sand. Background Technology

[0002] Methods for recovering and regenerating casting sand from casting cores are known. Patent Document 1 discloses a cleaning method that can efficiently remove binders from casting sand adhered to it.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2024-98711 Summary of the Invention

[0004] Cores remanufactured using casting sand recycled by the method described in Patent Document 1 sometimes exhibit lower strength compared to cores manufactured using new casting sand. Therefore, the inventors conducted in-depth research and discovered that minute irregularities are generated on the surface of the casting sand after the binder has been dissolved, which leads to a decrease in core strength.

[0005] The present invention was made in view of the following situation, and provides a method for regenerating casting sand that can suppress the reduction in strength of the remanufactured core.

[0006] The method for regenerating foundry sand according to the present invention comprises: a preparation step for preparing foundry sand with adhesive; a cleaning step for cleaning the foundry sand prepared in the preparation step; a grinding step for grinding the foundry sand after cleaning in the cleaning step; and a rinsing step for rinsing the foundry sand after grinding in the grinding step.

[0007] According to the present invention, a method for regenerating casting sand can be provided to suppress the reduction in strength of the remanufactured core.

[0008] The above and other objects, features and advantages of the present invention will be more fully understood from the following detailed description and drawings. Attached Figure Description

[0009] Figure 1 This is a flowchart of the method for regenerating foundry sand according to this embodiment.

[0010] Figure 2 This is a graph showing the flexural strength of cores made from new sand, recycled sand from the examples, and recycled sand from the comparative examples. Detailed Implementation

[0011] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments. The present invention is not limited to the following embodiments and can be appropriately modified without departing from the spirit of the invention.

[0012] Furthermore, for clarity, the following descriptions and figures have been appropriately simplified. Additionally, in this disclosure, the "~" sign indicating a numerical range includes the values ​​preceding and following it as the lower and upper limits.

[0013] Figure 1 This is a flowchart of the method for regenerating foundry sand according to this embodiment. Figure 1 As shown, the method for regenerating foundry sand in this embodiment includes steps S1 to S4.

[0014] Step S1 is a preparation process for preparing casting sand with binder. The binder is a substance that binds the casting sand together during core manufacturing; for example, water-soluble binders such as water glass can be used. In the preparation process, casting sand with binder can be obtained, for example, by crushing the core.

[0015] Step S2 is a cleaning process that cleans the foundry sand prepared in the preparation process. In this cleaning process, the adhesive adhering to the foundry sand is removed by mixing and stirring a solvent that dissolves the binder. If the binder is water-soluble, water can be used as the solvent. Particularly when the binder is water glass, water at 70°C to 100°C is preferred from the viewpoint of removal efficiency. Alternatively, water at 100°C to 120°C can be used under pressure higher than the saturated water vapor pressure. By setting the water temperature to 70°C or higher, the binder can be dissolved quickly, thus shortening the cleaning time.

[0016] Step S3 is a grinding process that grinds the foundry sand after it has been cleaned in the cleaning process. In this grinding process, the foundry sand is ground by rubbing its surface. The grinding method is not particularly limited; for example, grinding the foundry sand by rubbing it against itself is possible. A particularly preferred method is to rub the foundry sand against itself while it is being stirred in contact with a solvent such as water. Contact with a solvent improves the efficiency of the mutual friction between the foundry sand particles. Furthermore, using water as a solvent, in particular, allows for the efficient removal of water-soluble binders.

[0017] In step S3, when the foundry sand is stirred while being brought into contact with the solvent, causing the foundry sand to rub against each other, the amount of solvent is preferably 4% to 20% by mass of the foundry sand after the cleaning process. By making the amount of solvent 4% or more of the foundry sand, the foundry sand can easily come into contact with the solvent as a whole, which can improve the stirring efficiency. In addition, by making the amount of solvent 20% or less of the foundry sand, the dispersion of the foundry sand in the solvent can be suppressed, and the frequency of mutual friction between the foundry sand particles can be increased.

[0018] Furthermore, in step S3, when the foundry sand is stirred in water to cause friction between the sand particles, the stirring speed is preferably 1 to 12 m / s. By setting the stirring speed to 12 m / s or less, the impact applied to the foundry sand can be suppressed, and breakage of the foundry sand can be prevented. Additionally, by setting the stirring speed to 1 m / s or more, the grinding time can be shortened. When the stirring speed is 1 m / s or more, the grinding time can be set to 5 to 10 minutes.

[0019] Step S4 is a rinsing process for rinsing the foundry sand after it has been ground in the grinding process. In this rinsing process, the foundry sand is rinsed with clean water, thereby removing fine contaminants remaining on the surface of the foundry sand. The rinsing method is not particularly limited, but it is preferable to use a larger amount of water than the solvent used in the grinding process.

[0020] The casting sand regenerated by the methods described in steps S1 to S4 above has its binder removed in the cleaning process, and its surface becomes smoother by reducing the unevenness in the grinding process, thus making it suitable for core manufacturing.

[0021] Furthermore, in the example above, the method of performing steps S1 to S4 in sequence was described, but the grinding step (step S3) and the rinsing step (step S4) can also be performed in different orders. In this case, the rinsing step can remove fine adhesives and other residues remaining in the casting sand during the cleaning step, thus improving the grinding efficiency.

[0022] Furthermore, the method for regenerating foundry sand according to the present invention may also include a drying step (not shown) after step S4 to dry the foundry sand that has been rinsed in the rinsing step. By drying it, the foundry sand can be easily processed.

[0023] Furthermore, the method for regenerating foundry sand according to the present invention may also include a new sand mixing step (not shown) after the above-mentioned drying step, in which new sand is mixed with the dried foundry sand.

[0024] Next, an example of the method for regenerating foundry sand using the present invention will be described.

[0025] (Example 1)

[0026] First, the used core is crushed to prepare casting sand with adhesive. Next, the casting sand is washed with water at 120°C for 5 minutes at 0.15 MPa. Then, the casting sand is ground by stirring at 1 m / s for 5 minutes in a solution containing 17% by mass of water equivalent to the washed casting sand. Finally, the casting sand is rinsed with clean water to remove water and dried. This is used as the recycled sand in this example.

[0027] (Comparative example)

[0028] In the above steps, only the grinding process is omitted to produce recycled sand, which is used as the recycled sand for comparative example.

[0029] (Strength Test)

[0030] Cores of the same shape were manufactured using virgin sand, recycled sand from the example, and recycled sand from the comparative example. Bending strength was measured using a three-point bending test. The measurement results are as follows: Figure 2 As shown.

[0031] like Figure 2 As shown, the core manufactured using recycled sand in the comparative example has lower flexural strength compared to the core manufactured using virgin sand. On the other hand, the core manufactured using recycled sand in the embodiment has the same level of flexural strength as the core manufactured using virgin sand.

[0032] As will be apparent from the described disclosure, embodiments of the invention can vary in many ways. Such variations should not be considered as departing from the spirit and scope of the invention, and all such modifications that will be apparent to those skilled in the art are intended to be included within the scope of the claims.

Claims

1. A method for regenerating foundry sand, comprising: Preparation process: preparing casting sand with adhesive binder; The cleaning process involves cleaning the casting sand prepared in the preparation process. The grinding process involves grinding the casting sand that has been cleaned in the cleaning process. as well as The rinsing process involves rinsing the casting sand that has been ground in the grinding process.

2. The method for regenerating foundry sand according to claim 1, wherein, The grinding process is a process in which the casting sand is brought into contact with a solvent while being stirred, causing the casting sand to rub against each other.

3. The method for regenerating foundry sand according to claim 2, wherein, The amount of solvent is 4% to 20% by mass of the foundry sand after the cleaning process.

4. The method for regenerating foundry sand according to claim 2, wherein, The solvent is water.

5. The method for regenerating foundry sand according to any one of claims 2 to 4, wherein, The stirring speed in the grinding process is 1~12m / s.

Images