JPH0811272B2 - Mold coating method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of coating a mold for improving the accuracy and appearance of a casting mold when manufacturing the mold.

(Prior Art) In molds for molding dies, for example, sand molds, relatively coarse sand particles are used for the reasons of air permeability and strength. Therefore, at the time of casting, as shown in FIG. 5, the molten metal 31 penetrates into the inner wall of the mold 32, that is, between the particles of the mold sand 33, and what is called “aim” is generated at 34. The above aim 34 makes it difficult for the casting to be released from the mold, and further the roughness of the particles of the molding sand will help to roughen the casting surface. Therefore, it is impossible to obtain a casting having a fine texture and a fine surface.

Therefore, in order to obtain a product with a fine casting surface,
The surface of the mold 32 shown in the figure is coated with a powdery hydrous substance or fine sand to prevent the aim 34 from occurring (see Japanese Patent Application No. 62-222646). The powdery hydrous substance is directly used as the covering material 35, and fine sand is processed into a slurry-like covering material 35 together with water, alcohol, binder, etc., and then the surface of the mold 32 is applied by a brush, a spray, a dipping means or the like. Was covered with.

However, it is necessary to dry the mold because the coating material contains water, cracks and blisters occur in the coating material during the drying operation, and the coating material easily peels from the mold surface. Become. If the drying operation is not sufficiently performed, the water contained in the coating material during the casting operation using the mold is vaporized to form bubbles, which may affect the surface of the casting (product). Extend.

Therefore, a product of good quality cannot be obtained. Similarly, when the covering material is a material having a high hygroscopicity, there is a problem that the drying operation requires a lot of time, resulting in deterioration of workability and productivity and an increase in cost. Furthermore, since the coating material rises near the edge of the mold due to surface tension, sagging 36 occurs and it is difficult for the coating material to have a uniform thickness.
As a result, the precision of the mold is affected and the dimensional precision of the product deteriorates.

Therefore, a method of coating the coating material on the mold as shown in FIG. 2 by arranging the mold in the fluidized bed of the powdery coating material and then moving the mold up and down in the fluidized bed is proposed. Proposed (see Japanese Patent Application No. 62-233575). This eliminates the need to dry the mold.

(Problems to be Solved by the Invention) However, in the technique disclosed in Japanese Patent Application No. 62-233575, since the coating material does not sufficiently reach the deep part of the gap of the mold sand constituting the mold, a fine textured mold surface can be obtained. It cannot be formed, and the coating material adhered to the mold surface easily scatters. For this reason, the thickness of the coating material is not uniform, the mold precision is deteriorated, and it is not possible to obtain a casting having a fine-grained casting surface.

Therefore, an object of the present invention is to provide a method of coating a mold for obtaining a good product, which does not require a drying operation.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a powdery coating material.
The casting mold 8 is arranged in the fluidized bed 12 of 10 and the auxiliary material 11 having the bristle material 13 slidable on the casting mold 8 is slidably contacted with the covering material 10
Is coated on the mold 8.

(Function) Since the present invention is configured as described above, the coating material 10 in the fluidized bed 12 is slidably contacted with the surface of the mold 8 by the hair material 13 of the auxiliary material 11 to cover the deep part between particles on the surface of the mold 8. Fill the material 10. Furthermore, since the covering material 10 does not contain or contain water, no drying operation is required.

(Example) Below, one Example of this invention is described in detail based on drawing.

In FIG. 1, reference numeral 1 is a mold coating apparatus for carrying out the method of the present invention. The main body of this device 1 is a cylindrical main body 2, a base 3 for mounting the main body 2, and a perforated plate 4 arranged between the main body 2 and the base 3.
At the same time, it is bolted to the base 3.

The perforated plate 4 is provided with an installation member 9, and the installation member 9 sets the mold 11 inside the main body 2 by a fixing jig (not shown).

The base 3 forms a space inside with the porous plate 4, and the space and the inside of the main body 2 are communicated with each other by the pores 6 formed in the porous plate 4. In addition, a through hole 5 is formed in the side wall of the base 3.
Is provided, and a nozzle 7 for allowing a flowing gas such as air to flow into the base 3 is fitted into the through hole 5.

A cylindrical auxiliary member 8 is disposed inside the main body 2, and the auxiliary member 8 is moved in a predetermined direction such as vertical movement while being rotationally driven about a rotation axis 1 by a drive device (not shown). It Further, the bristles 13 are erected on the inner wall of the auxiliary member 8 to form a brush, and the bristles 13 slide on the surface of the mold 11 fixed to the installation member 9 by the driving device.
Further, this bristle material 13 is soft so that the surface of the mold 11 is not scratched, and the covering material 10 is rubbed on the mold 11 to mold it.
11 It has elasticity that allows it to be pushed into the deep part between the particles of the mold sand on the surface.

The coating material 10 is in the form of powder or granules having a particle size of 200 μm or less so as to enter between the particles on the surface of the mold 11 or into the depressions, and is provided inside the main body 2. The coating material 10 is for obtaining a product with a fine-grained casting surface,
Use clay minerals, natural minerals, artificial minerals or activated carbon. Sepiolite, palygorskite, diatomaceous earth, zeolite, vermiculite and the like as the clay mineral, silica sand, chromite sand, zircon side as the natural mineral,
Artificial minerals such as silica flour include alumina, synthetic mullite, and fused silica. The coating material 10 may be one or more of the above various materials. The coating material 10 is guided from the nozzle 7 to the inside of the base 3 and is made to flow by the flowing gas flowing into the main body 2 from the pores 6, and is flowed inside the main body 2 by the coating material 10 and the flowing gas. Form layer 12.

Next, the method of the present invention will be described using the apparatus having the above-mentioned configuration.

First, the mold 11 is fixed to the installation member 9, the mold 11 is covered with the auxiliary material 8, and then the flowing gas is introduced from the nozzle 7. As a result, the fluidized gas is introduced into the body 2 through the pores 6 and forms the fluidized bed 12 inside the body 2. At this time, dry air, hot air, or the like may be used as the flowing gas so that the coating material 10 does not absorb the water contained in the gas in the fluidized bed 12.

Next, when the driving device is operated, the auxiliary material 8 rotates about the rotation axis l, and the hair material 13 comes into sliding contact with the surface of the mold 11. Therefore, the coating material 10 in the fluidized bed 12 is rubbed between the particles on the surface of the mold 11, and the coating operation of the coating material 10 is started (see FIG. 2).

Subsequently, the auxiliary member 8 is rotated by the drive unit to rotate the rotary shaft l.
It is reciprocated in a predetermined direction while rotating around. As a result, the coating material 10 in the fluidized bed 12 is pressed and filled between the particles on the surface of the mold 11 and deep in the gap, so that the coating material 10 in the fluidized bed 12 uniformly covers the entire surface of the mold 11. (Third
(See Figure and Figure 4).

After the covering work is completed, the installation member 9 is moved to the mold 11
Then, the mold 11 is conveyed to the next step. The mold 11 is not dried.

Next, a specific example in which the mold 11 is coated with the coating material 10 by the above method will be described below.

First, as the mold 11, resin-coated molding sand (100 parts by weight of silica sand, 2 parts by weight of phenol resin, No. 6 grain) was used.
Upper outer diameter 73 mm, lower outer diameter 80 mm, height 110 mm, thickness 10 mm,
The hollow cylindrical body of
Sepiolite of 50 μm or less was used.

Further, the mold coating apparatus 1 has a main body 2 with a length of 330 mm and a width of 350 m.
The method of the present invention was carried out on the hollow cylinder (mold) using a material having a size of m and a height of 400 mm.

The rotation speed of the auxiliary material 8 is 0 rpm, 30 rpm, and 60 rpm.
The seeds are moved up and down 10 times by the installation member 9
3 times, 30 times, were tested as sample No. 1 to sample No. 9, respectively. The coating amount (g / m ² ) of each No. 10 coating material is as shown in Table 1 below.

As shown in Table 1, the amount of the coating material 10 coated on the mold 11 per unit area increases as the rotation speed of the auxiliary material 8 increases,
Further, the larger the number of vertical movements of the casting mold 11 by the installation member 9 is, the more it tends to increase little by little.

Next, the case of casting with the coating material 11 coated on the mold 11 by the above method, and the case of casting without coating, taking "Sample No. 5" in Table 1 above as an example, Compare the skin. This casting is 700
It is made by casting aluminum alloy (JIS AC2B) at ℃.

As a result, the roughness of the casting cast without coating the coating material 11 is 90 μm, while the roughness of the casting according to “Sample No. 5” is 32 μm, which is about 1/3. It was

(Effects of the Invention) As described above, the present invention can fill a coating material to a deep part between particles on a mold surface without performing a drying operation. For this reason, since the thickness of the covering material becomes even,
The mold precision is improved, the dimensional precision of the product is improved, and a fine-grained casting surface can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an apparatus for carrying out the method of the present invention, FIG. 2 is a sectional view showing a state in which a mold is placed in the fluidized bed shown in FIG. 1, and FIG. FIG. 4 is a sectional view showing the state of the covering material, the mold and the auxiliary material in the figure, FIG. 4 is a sectional view showing the state of the covering material and the mold after carrying out the method of the present invention, and FIG. FIG. 6 is a cross-sectional view showing the state of casting using, and FIG. 6 is a cross-sectional view showing the state of coating of the conventional mold and the coating material. 1 ... Mold coating device, 2 ... Main body 3 ... Base, 4 ... Perforated plate 5 ... Through hole, 6 ... Pores 7 ... Nozzle, 8 ... Auxiliary material 9 ... Installation member, 10 …… Coating material 11 …… Mold, 12 …… Fluidized bed 13 …… Bristles, l …… Rotating shaft

Front page continued (72) Inventor Kenji Kaida 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Yuji Sakakibara 41, Nagakute Town, Aichi-gun, Aichi Prefecture Toyota Corporation 1 41 Yokomichi In the Central Research Laboratory (72) Inventor Takatoshi Suzuki, Aichi Prefecture, Nagakute Town, Aichi Prefecture, Nagacho, Yoko 41 1 In the Toyota Central Research Institute Co., Ltd. (72) Inventor Yasuo Takada 1 in 41, Yokoshiro, Nagakute-cho, Aichi-gun, Aichi-gun 1 In Toyota Central Research Institute Co., Ltd. (56) References , U)

Claims (1)

[Claims] 1. A mold is placed in a fluidized bed of a powdery coating material, and an auxiliary material having a bristle material slidably contacting the surface of the mold is slidably contacted to coat the coating material on the mold. A characteristic method for coating a mold.