JPH01202336A - Surface treatment for casting mold and casting mold - Google Patents

Abstract

PURPOSE:To improve the casting surface and dimensional accuracy of a product by arranging coating material and assisting material for a flow layer type processing device, introducing a fluidized gas as well and moving a mold in the formed flowing layer. CONSTITUTION:A fluidizing treatment device 1 is provided, porous plate 11 and bottom part 15 are arranged at the lower part of a main body 10 and a nozzle 13 is fitted thereto. The mixed powder composed of covering material and assisting material is put onto the porous plate 11 having small holes 111 to inject the fluidized gas 14 of an air, etc., from the nozzle 13, the mixed powder is fluidized and a flowing layer 2 is formed. A mold 3 is then suspended into the flowing layer 2 and moved vertically or horizontally. The coating material is put by being pushed in into the surface hollow of the mold 3 and the surface layer part of the mold 3 is formed compactly and smoothly. Consequently the casting surface and dimensional accuracy of a casting product are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention forms a surface layer portion on the surface of a casting mold, which has the effect of reducing penetration of molten metal.

The present invention relates to a method for surface treatment of a casting mold and a casting mold having this surface layer portion.

[Prior art]

Mold 5 for metal casting For example, in a sand mold, the size of the sand used is relatively large due to the mold's strength and air permeability.

A coarse one is used. As a result, the poured molten metal tends to "infiltrate" the mold wall, and the casting tends to separate from the mold. In addition, some castings are made with the surface as they were cast, that is, the surface as they were cast.
In some cases, the roughness of the casting surface affects its value. Generally, the finer the grain, the better the accuracy and appearance.

Conventionally, methods such as coating the surface of the mold with fine sand have been used for this purpose. In addition, as a coating method for this mold, alcohol, water, etc. are added to the sand, and if necessary, a binder is added to form a slurry, and this is applied by brushing, spraying, etc. There is a method of coating by dipping.

[Problem to be solved]

However, these methods require a drying step after coating, and during drying, cracks, pristals, etc. occur in the coating material, and the coating material is likely to peel off. Furthermore, in the case of a coating material that easily absorbs moisture, etc., the drying process is time-consuming, increasing the number of steps and increasing costs. Furthermore, if drying is insufficient, moisture etc. adsorbed in the coating material during casting will evaporate.

Gas defects may also occur.

To briefly explain the above using FIGS. 5 and 6, generally speaking, when the mold surface 31 has a large roughness as shown in FIG.
"Aiming" 51 occurs or the casting surface becomes rough. Therefore, as shown in Fig. 6, if the coating material 6 is wet-coated on the mold surface 31 like a coating mold, the casting surface will be clean, but a drying process will be required. etc., and the coating material 6 is likely to peel off.

Furthermore, the thickness of the covering material 6 may affect mold accuracy.

The coating material sag 61 due to surface tension at the edge of the mold, making it difficult to make the thickness of the coating material 6 uniform, which affects the dimensional accuracy of the product.

On the other hand, as a method for manufacturing the main mold and core (hereinafter simply referred to as mold) of casting molds, the shell molding method, which takes advantage of the property of synthetic resins such as phenolic resins being hardened by heat, has traditionally been widely adopted. . This is because when casting is performed using a mold formed by this shell molding method, a casting with high one-dimensional accuracy can be obtained. As the mold material used in this shell molding method, molding sand (resin coated sand), which is made by coating sand grains such as silica sand with a thermosetting resin such as phenol resin, is used for boat fishing. Further, there is also a method of manufacturing a mold using a resin that hardens at room temperature, such as a cold box.

However, using molds made from molding sand coated with room-temperature curable resins or thermosetting resins (hereinafter simply referred to as resins), molten metals with relatively low casting temperatures, such as aluminum, magnesium, and their alloys, can be cast. If casting is carried out at -9, the decomposition of these resins will be insufficient, and substances such as tar that will promote the occurrence of casting defects will be generated. Then, these resins and the like adhere to vents for degassing and cause clogging, and furthermore, the generated gas flows toward the cavity side, leading to casting defects. In order to prevent this, it is necessary to frequently clean tar and the like adhering to the vent, which poses a problem of placing a heavy burden on maintenance.

In view of these problems, the present invention provides a surface of a casting mold that forms a surface layer that prevents molten metal from penetrating the mold wall and generates a small amount of substances that promote casting defects such as tar generated during casting. Processing method.

And, it is an object of the present invention to provide a casting mold in which a surface layer portion having the above-mentioned effects is formed.

[Means for solving problems] A method for surface treatment of a casting mold according to the present invention.

A mold surface treatment method for forming a surface layer on the surface of a casting mold, the method comprising: arranging a coating material and an auxiliary material having a larger diameter than the coating material in a fluidized bed treatment device; A step of introducing a fluidizing gas into a bed type processing device to fluidize the coating material and auxiliary materials to prepare a fluidized bed, and placing and holding the mold in the fluidized bed and moving the mold. By doing so, 1. The method comprises the step of filling and coating the surface portion of the mold surface including depressions using the acting force of the auxiliary material, and forming a surface layer portion having a smooth surface on the surface of the mold. A method for surface treatment of casting molds.

The fluidized bed processing apparatus used in the present invention fluidizes the coating material and the auxiliary material using a fluidizing gas such as air, as shown in FIG. 1, which will be described later.

The coating material includes clay minerals, natural minerals, artificial minerals,
One or more types of powder or granular powder, such as activated carbon, are used to fill the cavities on the surface of the mold. The above clay minerals include seviolite, palygorskite, diatomaceous earth, and zeolite.

There is vermiculite, etc. Furthermore, examples of the above-mentioned natural minerals include silica sand, chromite sand, zircon sand, and silica flour. The above artificial minerals include alumina,
There are synthetic mullite, fused silica, etc.

Further, among the coating materials, porous substances are suitable materials because they further reduce the generation of tar generated when casting using a shell mold. This porous material is
There are hydrous magnesium silicate clay minerals, activated carbon, activated alumina, zeolites, etc., and one type or a mixture of two or more of these types is used.

Among these, hydrated magneusilum silicate clay mineral is.

The main component is hydrated magnesium silicate, and the specific surface area is 10.
It is large at 0 to 400nf/g. Specifically, the hydrated magnesium silicate clay mineral is sepiolite.
te), Xyl.

tile), Loughlinit
e), falcondite (Falcond.

1te), palygorskite whose main component is hydrated aluminum silicate, and the like. This material is also commonly known as mountain cork (Mou).
ntain cork), mountain wood (Mou
tain wood).

Mountain leather (Mountain 1eathe)
r), sepiolite (Meers-chaμm).

It is a mineral called attapulgite.

In addition, activated carbon has a specific surface area of 400 to 2000 rtr/
There are 1) vegetable materials such as coconut shells and ash, 1) coal-based materials, and 9) mineral materials manufactured from petroleum-based raw materials.

Activated alumina is obtained by heating hydrated alumina to a high temperature, and is intermediate alumina in the process of becoming α-alumina, and has a specific surface area of 50 to 400 rrf/g. This intermediate alumina is also called anhydrous alumina. Among these are ρ, χ, η, and T.

δ, θ, alumina, boehmite, etc. are included.

The particle size of the coating material is large enough to fit into the depressions on the surface of the mold, but it is preferably about 200 μm or less, if it exceeds 200 μm.

It is difficult to obtain a smooth surface layer.

Furthermore, it is more preferable that the particle size of the coating material is 1 to 150 μm. This is because if the particle size is less than 1 μm, it is difficult to fluidize the coating material, and the coating material may become fluidized. This is because it is easy to scatter outside the treated layer. Also, 150μ
This is because if it exceeds m, it is difficult to fit into the depression. When the particle size is 1 to 150 μm, a smoother and finer-grained surface layer can be obtained.

In addition, the auxiliary material is used to better fill and adhere the coating material to the depressions on the mold surface, and is one particle size compared to the coating material so that it is easier to apply force in the direction of the depressions.

It is preferable to use a material having a high density on one or both sides.

The auxiliary material has a rounded shape and a particle size of 9 to 1.
0000 μm is preferable. The particle size of the auxiliary material is 50μ
If it is smaller than m, more of the auxiliary material than the coating material will adhere to the mold surface, making it difficult to achieve the original purpose of 9. Also, 10000 μm
If it is larger than , the amount of fluidizing gas supplied for fluidizing the auxiliary material will be increased, and the powdery coating material will be more likely to scatter out of the fluidized bed. Note that the particle size is particularly 150 to 500I.
It is more preferable to set it to m. If it is within the range.

The above objectives can be better achieved. Further, it is preferable that the particle size of the auxiliary material is larger than the size of the depression on the surface of the mold.

In addition, clay minerals can be used as such auxiliary materials.

It is preferable to use one or more of natural minerals, artificial minerals, and activated carbon.

Next, the covering material and auxiliary materials configured as described above.

The product is placed in the fluidized bed processing apparatus, and a fluidizing gas is introduced to fluidize the TFI coating material and the auxiliary material to form a fluidized bed.

Here, in order to fluidize the coating material and the auxiliary material, air, nitrogen, oxygen, or an inert gas is introduced from below the fluidizing device. Also, at this time.

Dry air or hot air may be used to prevent the covering material from adsorbing moisture in the atmosphere.

Next, the mold is placed and held in the fluidized bed formed as described above, and the mold is moved using the acting force of the auxiliary material.

The coating material is filled and coated on the surface of the mold, including the depressions.

That is, when coating the recesses on the surface of the mold with the coating material, the mold is placed in a fluidized bed of the fluidized coating material and auxiliary material. This arrangement is performed by, for example, suspending the mold. And to coat the surface of the mold with the coating material as uniformly as possible.

It is mainly moved repeatedly in the vertical direction. Also.

It can be moved not only up and down, but also in forward and backward directions, and left and right.

Furthermore, when coating a mold with a complex shape, many movements are combined, not just in one direction, in order to avoid leaving any uncovered parts and to uniformly coat the entire surface. Note that the mold may be placed in the fluidized bed processing apparatus not only after the fluidized bed is formed as described above, but also before the fluidized bed is formed and before the fluidizing gas is introduced.

In addition, there is an excess of coating material on the mold surface after coating treatment.

Alternatively, if some auxiliary materials are attached, by removing them with compressed air or the like, a mold with a smooth mold surface and good dimensional accuracy can be obtained.

In addition, the surface layer obtained by filling and coating the surface area of the mold surface, including the recessed areas, with the above-mentioned surface treatment method is not particularly limited as long as it has the above-mentioned effects, Also includes aspects such as, i.e., the first aspect of
This is a case where the coating material is filled only into the depressions on the mold surface. The second case is a case in which the coating material is filled and coated into the depressions on the surface of the mold, and further, the coating material is filled and coated into at least part of the surface portion other than the depressions.

Third, the coating material is filled and coated over the entire desired portion of the mold surface, including the recessed portions of the mold surface.

This is the case when a thin coating layer is formed. in this case.

If the coating layer is thick, it is not preferable because there is a possibility that the dimensional accuracy of the product will be deteriorated when the mold is used for casting.

Next, a casting mold in which a surface layer of porous substance powder is formed on the surface of the mold will be described.

The casting mold consists of a cavity for determining the shape of the casting, and a mold body for configuring the cavity. and a hydrous magnesium silicate clay mineral on the surface of the mold body including the depressions.

A casting mold characterized by having a surface layer formed by filling and coating powder of one or more porous substances such as activated carbon and activated alumina.

However, as the above-mentioned room temperature curable resin, phenol and
Examples include polyisocyanate resin, phenol/furan resin, and furanurea resin. Also.

Borac type phenolic resin is a thermosetting resin.

resol type phenolic resin, urea resin, melamine resin,
There are silicone resins, furan resins, etc.

The porous substance powder filled on the surface of the mold is the above-mentioned hydrated magnesium silicate clay mineral.

One or more types of activated carbon and activated alumina are available.

The specific details of these are the same as those described in the surface treatment method. In addition, the particle diameters of these powders are the same as those described for surface treatment method 1.

Preferably 200 μm or less, more preferably 1 to 100 μm
It is μm.

[Action and effect]

According to the above-mentioned surface treatment method, it is possible to form a surface layer portion in which there is little intrusion of molten metal into the mold wall of a casting mold, and in which there is little generation of substances that promote the occurrence of casting defects, such as tar. Furthermore, the coating material can be filled deep into the depressions on the surface of the mold without performing a drying process.

The mechanism by which the surface treatment method exhibits the above effects is not clear, but it is thought to be as follows.

In Figures 2 to 4, if only the coating material 20 is fluidized and coated on the mold, it will be coated for a while as shown in Figure 2, but it will be coated to the bottom of the gap between the molding sand 30 that makes up the mold. The coating material 20 tends to scatter because the coating material 20 does not reach the surface sufficiently.However, if the coating material 20 is mixed with the auxiliary material 21 and the mold is moved within it, there will be a gap between the mold surface 31 and the auxiliary material 21. It is thought that a resistance force acts and the acting force of this auxiliary material 21 pushes the covering material 20 into the gap as shown in FIG.

That is, near the depressions on the surface of the mold, a coating material smaller than the depressions and an auxiliary material larger than the coating material are uniformly present in a fluid state. When the mold is moved in the vertical direction in this state, the recess moves relative to the auxiliary material, and the coating material is pushed into the bottom of the recess by the acting force of the auxiliary material, which is greater than the recess. By repeating the movement, the coating material in the depression increases each time the auxiliary material passes through the depression, and finally fills the depression. Since the auxiliary material advances while being in contact with the mold surface, the excess coating material is pushed along with the auxiliary material in the direction of movement of the auxiliary material or enters into the recess. Therefore, the coating material is densely present in the depression, and after the auxiliary material has passed, the surface of the depression where the coating material is buried forms a smooth surface.

Also, excessive coating material 20. Furthermore, if some auxiliary materials 21 are attached, remove them with compressed air or the like after the coating process, and as shown in FIG. 4, a mold with a smooth mold surface 31 and good dimensional accuracy can be obtained. It will be done. Therefore, if such a mold is used for casting, it is possible to obtain a cast product with a clean casting surface without causing the casting.

Next, the functions and effects of a casting mold in which a surface layer of porous substance powder is formed on the surface of the mold will be described.

The casting mold has little intrusion of molten metal into the mold wall,
In addition, the amount of substances that promote casting defects, such as tar, generated during the production of castings is small. Further, the casting mold has good mold accuracy. Therefore, the dimensional accuracy of the product is good, and a casting with a finely textured surface can be obtained.

The mechanism by which this casting mold exhibits this effect is not necessarily clear, but it is thought to be of the first order.

That is, 1. Normally, the surface of a mold has severe irregularities such as depressions, and has holes that penetrate deeply into the mold. 9. In the present invention, a surface layer made of powder of a porous substance is formed on such a surface. ing. Therefore, the surface layer 1 has a dense and smooth surface, with little penetration of molten metal, so-called aiming, and good release from the mold.

In addition, the coating material filled into the depressions on the surface of the mold is
It consists of a powdery porous substance, while the components of resin generated during casting can be considered to be mainly polymeric. Therefore, some of the components of resin are adsorbed by the porous material, or some of them are decomposed by the catalytic action of the porous material to produce H, O,
It becomes low molecules such as Co, CH4. Therefore, it is thought that the amount of tar produced decreases.

Furthermore, in the casting mold described above, the cavities between the sand grains and the surface of the mold are coated with the porous substance, and since no foreign matter (porous substance) is mixed into the inside of the mold, the strength of the mold is not reduced.

〔Example〕

First example Fluidized bed processing equipment as shown in Figure 1 (hereinafter referred to as "fluidized bed processing equipment").

The surface of the mold was treated using sepiolite powder, which is a hydrous magnesium silicate clay mineral, as a covering material and an auxiliary material.

That is, as shown in FIG. 1, the flow device 1 consists of a rectangular cylindrical main body 10, a perforated plate 11 provided below the main body 10, and a bottom portion 15. At the bottom 15.

A nozzle 13 for introducing fluidizing gas is provided.

When coating the mold with the coating material, a mixed powder consisting of the coating material and the auxiliary material is placed on the perforated plate 11 having pores 111, and a fluidizing gas such as air 14 is passed through the nozzle 13.
is introduced and the gas 14 is ejected from the pores 111 to fluidize the mixed powder.

The fluidized bed 2 is formed. In this fluidized bed 2, a mold 3 as an object to be treated is suspended by a hanging tool 4. The hanging tool 4 also moves the mold 3 in the fluidized bed 2 in the vertical direction, as well as in the front-back and left-right directions. As a result, the coating material enters and fills the depressions on the surface of the mold. This filling is mainly performed by the auxiliary material acting to push the covering material in the direction of the recess.

Concerning the above, specific examples are shown below.

First, using resin-coated foundry sand (100 parts by weight of silica sand, 2 parts by weight of phenolic resin, 2 grain size No. 6), the outer diameter of the upper part was 73 mm.
, lower outer diameter 80nm, height 110r! n.

A hollow cylindrical body as a mock mold with a thickness of 10+nm was produced. The resin-coated foundry sand was equivalent to JIS No. 65 and had a particle size distribution of 50 to 600 μm.

Next, Sevioly) 3 with a particle size of 50 μm or less was used as a coating material.
．． 75 parts by weight and the particle size shown in Table 1 is 150 to 380μ
Three types of auxiliary materials, namely 25 parts by weight of sepiolite and 100 parts by weight of silica sand or spherical muli, were mixed respectively. Then, these mixtures were placed in the fluidized bed W1 having internal dimensions of 330 m in length, 350 m in width, and 400 m in height. And i
Compressed air as a Jt mobilizing gas was supplied to form a fluidized bed 2 of the mixture, and then the simulated mold 3 was placed therein and moved up and down 20 to 60 times for 20 to 60 seconds.

Thereafter, the mold 3 was taken out of the fluidizer Wl, and the excess coating material was removed with compressed air. As shown in the fourth example above, the surface of the mold 3 was filled with the coating material to the inside, and had a smooth mold surface. Next, the amount of coating material coated on the surface of the molds thus obtained (samples Nα1 to Nα9) was measured. The result is the amount of air used as coating material, auxiliary material, and fluidizing gas.

Table 1 shows the conditions for the number of vertical movements of the mold during processing.

For comparison, the surface treatment was performed while the mold remained stationary without moving up and down (NαC1 to C3).

The results are also shown in the same table.

As can be seen from Table 1, the amount of coating tends to gradually increase as the number of vertical movements increases.

Moreover, the mixture with the largest amount of coating was the case where spherical mullite was used as an auxiliary material. In addition, when sepiolite was used as the auxiliary material, the amount of coating was relatively large, but compared to the case where single spherical mullite was used, it tended to be difficult to coat the areas where the depressions between the sand grains of the mold were large. This is thought to be due to the fact that the effect of pushing the covering material in the direction of the depression is small. In addition.

When silica sand was used as an auxiliary material, a large amount of air was required for fluidization, and the amount of coating was small.

Furthermore, when sepiolite or spherical mullite is used as an auxiliary material, the amount of air for fluidization may be small, so scattering of the coating material is less likely to occur, and the mold is uniformly coated with Seviolite as the coating material.

Moreover, as is clear from the same table, in the comparative examples (kc1 to C3) in which the mold was not moved up and down, the amount of coating was extremely small.

Further, in this case, the amount of coating on the lower part of the mold was larger than the amount of coating on the upper part.

] Second Example The effect on the casting surface was investigated when silica sand was used as the coating material and spherical mullite was used as the coating auxiliary material.

First, we made a 20M thick sandbox made of raw sand (grain size No. 6) with a cavity measuring 70mm in length and 70mm in width and 10mm in width.
A rectangular mold with an open section was prepared, and then 10 parts by weight of silica sand or spherical mullite with a diameter of 70 μm or less was added to the flow device used in the first example as a coating material.

150~380!1m spherical mullite 10 as an auxiliary material
0 parts by weight of the mixture was added to form a fluidized bed.

Then, the above-mentioned mold was placed in this for 50 seconds and moved up and down 50 times to coat the surface of the mold with the above-mentioned coating material (
Sample Nα10,11). Next, the mold was backed up with a steel jig and heated to 700°C using an aluminum alloy (JISAC2
B) was cast and the roughness of the casting surface was measured.

As a result, as shown in Table 2, in the case of the comparative mold without coating (N (LC4)), the roughness of the back side of the casting was 110 μm, but in the case of the mold coated with silica sand or spherical mullite ( When Nα10.11) was used, the roughness was reduced to 35 μm, about 1/3.8 Thus, according to the surface treatment method of the present invention, it is possible to easily apply a mold to improve the casting surface. Can be done.

Table 2 3rd Example A shell mold made of resin-coated molding sand was coated with porous materials of sepiolite coconut shell activated carbon 1 coal-based activated carbon and activated alumina, silica sand, and mullite, and a performance evaluation test by casting was conducted.

First, using commercially available resin-coated foundry sand (100 parts by weight of silica sand, 2 parts by weight of phenolic resin, 3 grain size No. 6), the outer diameter of the upper part was 8.
A cup-shaped mold with a lower part outer diameter of 71 m, a height of 137 m, an upper inner diameter of 60 m, a lower inner diameter of 52 m, and a depth of 120 m was manufactured.

Next, the above-mentioned powdery porous substance with a particle size of 50 μm or less and other coating materials were applied to Example 1 except for the conditions shown in Table 3.
The inner and outer surfaces of the cup-shaped molds were coated under the same conditions as (Samples Nα12 to 17).

Next, the amount of coating material on the mold surface was measured.

In addition, in order to evaluate the performance of the mold, casting was performed. Casting was performed by pouring an aluminum alloy (JISAC2B) previously melted at 750°C into a mold.

To measure tar as a substance that promotes the occurrence of casting defects, a semicircular spherical evaporation dish with a diameter of 145 m is fixed at 10 m above the mold, tar for 4 molds is attached to it, and the weight of this tar is measured. It was done by doing. The results obtained are shown in Table 3. For comparison, a case where no coating material was applied is shown (sample number C5).

As is clear from Table 3, the mold surface was sufficiently coated with the coating material by the surface treatment method according to Example 1 of the present invention. In addition, molds using porous materials as covering materials (
Nα12-15) has a tar generation amount of 20-b during casting compared to the comparative example (NαC5) Silica sand (Nα16) and mullite (Nα17) which are not substances
compared to the porous material.

There was a lot of tar generated.

Fourth Example Regarding a mold made of resin-coated molding sand coated with sepiolide and a comparative example of a mold made of resin-coated molding sand to which sepiolite was added.

A performance evaluation test was conducted.

First, using the same resin-coated molding sand as in Example 1 and 3, a cup-shaped mold of the same shape is made, and the molding sand 100 of the mold is coated on the inner and outer surfaces of this mold in the same manner as in Example 3.
0.5 parts by weight of sepiolite was coated with respect to parts by weight (
Sample Nα18).

Next, 0.5 parts by weight of sepiolite was added to 100 parts by weight of the same foundry sand as above and mixed, and molded by a conventional method to produce a cup-shaped mold having the same shape as above (sample NαC6).

Next, in order to evaluate the performance of these molds, aluminum alloy (JISAC2B) was poured into the molds in the same manner as in the third example, and the amount of tar produced was determined in the same manner as in the third example. For comparison, the coating of ce and olide was also applied to the mold without the addition of ce and olide to the mold (sample N).
Similar measurements were made for αC7). These results are also shown in Table 4.

As is clear from Table 4, the mold according to the present invention generates 1/1 the amount of resin during casting compared to the NαC7 mold.
It has decreased to nearly 2. but.

Mold with sepiolite added and mixed with foundry sand (sample N
aC6) produced a large amount of smoke at this level of addition, and produced a large amount of tar similar to that of the sample NαC7 to which no sepiolite was added.

In this way, when the surface of the mold is coated with sepiolite, the generation of tar can be significantly reduced compared to when sepiolite is added to foundry sand.

Further, when the strength of a mold (sample KC6) prepared by mixing cerecoide powder and foundry sand was examined, it was found to be a little brittle compared to the mold of the present invention. This is thought to be due to the presence of foreign matter (sepiolite) in the foundry sand.

Table 4 5th Example Sepiolite was used as the coating material, and a mold was surface-treated in a fluidized bed with varying amounts of sepiolite, and a performance evaluation test was conducted by casting.

First, using the same commercially available resin-coated molding sand as in the third example, a cup-shaped mold having the same size as in the third example was produced.

Next, powdered sepiolite with a particle size of 43 μm or less is prepared as a coating material, and spherical synthetic mullite with a particle size distribution of 50 to 330 μm is prepared as an auxiliary material.
A mixture containing sepiolite in the proportions shown in Table 5 based on parts by weight was prepared. The mixture was then placed in the fluidizer shown in Example 1, and compressed air was introduced as a fluidizing gas at the flow rate shown in Table 5 to form a fluidized bed of the mixture.

Next, the cup-shaped mold is placed in the fluidized bed.

The inner and outer surfaces of the mold were coated with the cerolide by moving the mold 40 times, mainly in the vertical direction, for 40 seconds. Afterwards, the excess covering material was removed from a distance of 300 km.
By blowing and removing 2 kg/cd of compressed air, casting molds of this example (samples NCL19 to 24) were obtained.

The obtained casting mold was subjected to a coating amount measurement test and a casting evaluation test.

First, the amount of coating material on the surface of the casting mold was measured. The results are shown in Table 5. From the same table, the amount of sepiolite in the fluidized bed is 2 parts by weight per 100 parts by weight of the auxiliary material.
~10 parts by weight.

It can be seen that the mold has a surface layer with sufficient coverage and good surface texture.

Next, regarding the molds of samples Nα19, 21.23.

A casting evaluation test was conducted in the same manner as in the third example. The results are also shown in Table 5. From the same table.

It can be seen that all of the molds according to the present invention have low tar generation. Moreover, the surface roughness of each casting surface was approximately 35 μm and smooth.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing a mold coating method according to an embodiment of the present invention, FIGS. 2 to 4 are explanatory diagrams showing the functions and effects of the present invention, and FIG. 5 is an intended state. FIG. 6 is a diagram showing a conventional surface treatment method. 110. Flow device. 10. Main body 11. , , perforated plate. 201. Fluidized bed 1 20, coating material, 21. ,, Auxiliary material. 301. template. 30., Foundry sand, 31. ,, mold surface. 500. Molten metal, 51. ,,Aim. 619. Conventional dressings, 61. ,, sauce. Applicant Toyota Central Research Institute Co., Ltd. Toyota Motor Corporation Agent Patent Attorney Yoshiyasu Takahashi 1st Figure 4 Ln -

Claims (12)

[Claims] (1) A mold surface treatment method for forming a surface layer on the surface of a casting mold, which comprises the steps of placing a coating material and an auxiliary material with a larger diameter than the coating material in a fluidized bed treatment device; , a step of introducing a fluidizing gas into the fluidized bed processing apparatus to fluidize the coating material and the auxiliary material to prepare a fluidized bed; and arranging and holding the mold in the fluidized bed. A step of filling and coating the surface portion of the mold surface, including depressions, by moving the mold and using the acting force of the auxiliary material, the surface layer portion having a smooth surface on the surface of the mold. 1. A method for surface treatment of a casting mold, characterized by forming. (2) In the surface treatment method according to claim 1, the coating material is a powder of one or more of clay minerals, natural minerals, artificial minerals, and activated carbon. Method. (3) In the surface treatment method according to claim 2, the coating material is powder of one or more porous substances selected from hydrous magnesium silicate clay mineral, activated carbon, and activated alumina. Mold surface treatment method. (4) The surface treatment method for a casting mold according to claim 1, wherein the particle size of the coating material is 200 μm or less. (5) The surface treatment method for a casting mold according to claim 4, wherein the particle size of the coating material is 1 to 100 μm. (6) In the surface treatment method according to claim 1, the auxiliary material is a powder of one or more of clay minerals, natural minerals, artificial minerals, and activated carbon. Method. (7) The surface treatment method for a casting mold according to claim 6, wherein the particle size of the auxiliary material is 50 to 10,000 μm. (8) The surface treatment method for a casting mold according to claim 7, wherein the particle size of the auxiliary material is 150 to 500 μm. (9) A method for surface treating a casting mold according to claim 1, characterized in that the mold is moved primarily in the vertical direction. (10) A casting mold consisting of a cavity for determining the shape of the casting and a mold body for configuring the cavity, wherein the mold body is made of a room-temperature curing resin or a thermosetting resin and molding sand. The surface of the mold body, including the depressions, has a surface layer portion formed by filling and coating the powder of one or more porous substances of hydrated magnesium silicate clay mineral, activated carbon, and activated alumina. A casting mold characterized by: (11) The casting mold according to claim 10, wherein the powder of the porous substance has a particle size of 200 μm or less. (12) The casting mold according to claim 10, wherein the powder of the porous substance has a particle size of 1 to 100 μm.