JP2609210B2 - Mold manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to moldings and castings requiring a smooth surface,
Alternatively, the present invention relates to a mold used when manufacturing a mold or a resin mold requiring a smooth surface.

[Background of the Invention]

Normally, when making a mold by the full mold method or when molding a molded product, use a mold made of thermoplastic foam and bury it in sand with a sprue, runner, weir, and soften by heat After the mold is removed by shrinking, burning, or injecting and dissolving a solvent or the like, a molten metal or a resin melt is added to produce a desired cast or molded article, or the mold is removed. In this method, a molten metal (molten metal) is directly injected without causing the molten metal to shrink, melt, or burn the mold and release the gas as a decomposition gas.

Since the molding die is made of a thermoplastic foam, the surface is rough, the surface of a molded product obtained from the molding die is also rough, and in the case of a casting, the so-called casting surface becomes worse,
When molding a molded product or casting having a smooth surface,
It was a big problem.

[Conventional technology]

Conventionally, a method of attaching an adhesive tape to a mold surface of a mold made of a thermoplastic foam, making the raw material beads of the thermoplastic foam finer, or applying a smoothing agent to the mold surface ( Tokiko 57-37
No. 416) has been proposed.

[Problems to be solved by the invention]

However, in the above prior art, when an adhesive tape is stuck on the mold surface of the molding die, the adhesive layer is hardly adapted to irregularities on the surface of the thermoplastic foam, and it is difficult to give perfect smoothness to the mold surface. The method of miniaturizing the raw material beads and reducing the bead gap in the molded body to reduce the foaming ratio improves the smoothness of the casting surface to some extent, but increases the bulk specific gravity, causes poor running of the molten metal, complete A smooth surface cannot be obtained. Further, when a smoothing agent is applied, coating unevenness is likely to occur, and it is difficult to apply a coating having a uniform film thickness.

[Means for solving the problem]

The present invention provides a mold (A) made of thermoplastic foam as means for solving the above-mentioned conventional problems.
A film (B) having a smooth surface and made of a heat-fusible or flammable or soluble material, a mold (A) provided on the back surface of the film (B), and the film Polymerizing a composite film (D) comprising a heat-sensitive adhesive layer (C) having a lower melting point than the material constituting (B),
The composite film (D) is hot-pressed to a temperature not lower than the melting point of the heat-sensitive adhesive layer (C) and not higher than the melting points of the mold (A) and the film (B). A method for producing a mold, in which the composite film (D) is pressed onto the mold surface of the mold (A) and the heat-sensitive adhesive layer (C) is filled into the irregularities of the mold surface of the mold (A). It is a suggestion.

The mold (A) made of a thermoplastic foam according to the present invention is a mold made of a thermoplastic foam such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene, and is particularly easily soluble in a solvent and Polystyrene foam, which softens and shrinks or burns out quickly upon heating, is a desirable material. Bees molding method to make the mold with polystyrene foam,
An ordinary method such as cutting of a polystyrene foam is used.

The film (B) made of a heat-fusible or flammable or soluble material having a smooth surface used in the present invention is, for example, a thermoplastic film such as polyethylene, polypropylene, polystyrene, polymethacrylate, or polyvinyl chloride; Ethyl cellulose, methyl cellulose, ethoxy cellulose, methoxy cellulose, carboxymethyl cellulose and other cellulose derivative films,
The surface of metal film or paper is smooth and heat-meltable,
Alternatively, it is a film made of a flammable or soluble material.

The heat-sensitive adhesive used in the present invention is polyethylene,
Polypropylene, vinyl acetate, vinyl acetate, vinyl acetate-ethylene copolymer, paraffin, microcrystalline wax, crude wax, petroleum wax such as chlorinated paraffin, wood wax, white wax, carnauba, dense wax, caster wax, candy wax Animal and plant waxes such as rosin, dammer, copal, shellac, hydrogenated rosin, rosin ester, ester gum, cumarone, indene, rosin derivatives such as terpene, petroleum resins such as polybran and polyisobutylene, and sirenic acid A material that melts and flows at a relatively low temperature, such as solid plasticizers such as bis-saleic acid resin, polyester resin, polyamide, cyclohexyl phthalate, and dimethyl isophthalate; these may be used alone or as a mixture of two or more. You may.

The heat-sensitive adhesive layer (C) using the heat-sensitive adhesive is provided on the back surface of the film (B) and is a composite film (D).
Is configured.

The melting point of the heat-sensitive adhesive used in the present invention is selected from those having a lower melting point than the thermoplastic foam as the material of the mold (A) and the film (B) having a smooth surface. If a material having a melting point higher than that of the thermoplastic foam is used, the heat-sensitive adhesive layer (C) is heated and melted.
And it is necessary to heat at a temperature higher than the melting point of the film (B), and when the composite film (D) is heated and pressed to the mold (A), the mold (A) may be deformed. Also, the film (B) having a smooth surface may be deformed and lose surface smoothness.

In order to provide the heat-sensitive adhesive layer (C) on the back surface of the film (B) having a smooth surface according to the present invention, the heat-sensitive adhesive is heated to a temperature not lower than the melting point and not higher than the melting point of the film (B). After the heat-sensitive adhesive is melted or semi-fluidized, it is applied by roll coater application, brush application, spray application, or in the form of an emulsion, a dispersion or a solution dissolved in a solvent. After being applied or dispersed in a solid state such as powder or pellets, the mixture is heated and melted at a temperature not lower than the melting point of the heat-sensitive adhesive and not higher than the melting point of the film (B), and is spread and adhered to the film (B). Further, the film thickness needs to be a film thickness sufficient to fill the irregularities of the mold surface of the molding die made of a thermoplastic foam, and therefore depends on the mold surface roughness of the molding die. Is usually about 0.1 to 2 mm.

The composite film (D) composed of the film (B) provided with the heat-sensitive adhesive layer (C) on the back surface has a smooth surface depending on the shape of the required mold, and a partial smoothness. May be cut out into an arbitrary shape in advance or pressed and punched out according to the shape of the portion.

In order to carry out the present invention, a heat-sensitive adhesive layer (C) is provided on a mold surface of a mold (A) made of a thermoplastic foam.
A composite film (D) consisting of a film (B) having a smooth surface provided on the back surface is laminated with the heat-sensitive adhesive layer (C) facing down, and the melting point or softening of the heat-sensitive adhesive layer (C) The heat-sensitive adhesive layer (C) is pressed in a fluid state or a semi-fluid state by heating to a temperature not lower than the melting point or the softening point of the mold (A) and the film (B). Then, the film (D) is cooled and solidified, and the film (D) is bonded to the surface of the mold (A) made of a thermoplastic plastic foam. Further, in order to adhere the film (B) provided with the heat-sensitive adhesive layer (C) on the back surface to the mold surface of the mold (A), the film may be pressed using a press plate heated to the above temperature. If necessary, a release paper may be polymerized and pressed with a heated pressing plate on the composite film (D) comprising the film (B) provided with the heat-sensitive adhesive layer (C) on the back surface. The release plate may be coated with a release agent or subjected to Teflon processing. In the step of bonding the composite film (D) on the mold surface of the molding die (A),
The melt of the heat-sensitive adhesive layer (C) of the composite film (D) is filled into the irregularities of the mold surface of the mold (A), and the film (D) secures surface smoothness.

The molding die (A) of the present invention is embedded in sand to which a gate, a runner, and a weir is attached, and then softened and shrunk or burned by heat, or dissolved by injecting a solvent or the like. After removing (A), a molten metal or a resin melt is injected, or a molten metal is directly injected, or a molding material such as a glass fiber reinforced plastic or a mixture of molding sand and a binder is formed around the molding die (A). The mold (A) is softened, shrunk or burned out by heating or dissolved by a solvent to easily mold a mold, casting or molded product having a smooth surface. You can do it.

[Action]

A composite film (D) composed of a film (B) having a heat-sensitive adhesive layer (C) provided on the back surface on a mold surface of a molding die (A) made of a thermoplastic plastic foam, is provided on the heat-sensitive adhesive layer. Polymerizing (C) downward and heating to a temperature not lower than the melting point or softening point of the heat-sensitive adhesive layer (C) but not higher than the melting point or softening point of the mold (A) and the film (B). The heat-sensitive adhesive layer (C) is brought into a fluidized state or a semi-fluidized state, and the film (D) is adhered to a mold (A) made of a thermoplastic foam.
The heat-sensitive adhesive layer (C) is cooled and solidified in a state where the heat-sensitive adhesive layer (C) is filled in the unevenness of the mold surface of the mold (A). Thus, the heat-sensitive adhesive layer (C) is filled into the irregularities of the mold surface of the molding die (A) made of the thermoplastic foam, and the surface smoothness of the film (B) is ensured. Thereby, a smooth mold surface is formed on the surface of the mold (A).

〔The invention's effect〕

Therefore, according to the present invention, the mold surface of the mold made of the thermoplastic foam can be smoothed by a simple method.

Embodiment 1 FIGS. 1 to 4 show Embodiment 1. FIG.

The molding base (1) shown in FIG. 1 is made of bead-formed polystyrene foam, and is made of polymethacrylate on the mold surface (2) of the molding base (1) as shown in FIG. With front side, and 70 parts paraffin on the back side,
A composite film (3A) composed of a film (3) having a heat-sensitive adhesive layer (4) formed of a mixture of 30 parts of a vinyl acetate-ethylene copolymer is overlaid, and as shown in FIG. A press (5) heated to a temperature not lower than the melting point or softening point of (4) and not higher than the melting point or softening point of the film (3) is pressed, and then cooled to be cooled. When the heat-sensitive adhesive layer (4) filled in the unevenness of the mold surface (2) is solidified, a film (6) having a smooth surface as shown in FIG. )
Is obtained.

Second Embodiment FIGS. 5 to 8 show a second embodiment.

The cylindrical molding die (8) shown in FIG. 5 is made of a heat-formed polystyrene foam, and has a smooth surface as shown in FIG. 6 on the mold surface (9) of the molding die (8). A composite film having a heat-sensitive adhesive layer (10) formed of a mixture of 80 parts of crude wax and 20 parts of polyisobutylene formed on the back surface of a film (11) made of ethyl cellulose having The composite film molded body (12) punched according to the shape of (9) is placed on the mold surface (9) of the molding base (8) as shown in FIG. 7, and the melting point of the heat-sensitive adhesive layer (10) Alternatively, after hot-pressing at a temperature equal to or higher than the softening point and equal to or lower than the melting point or the softening point of the film (11) and the film (11), the film is cooled to form irregularities on the mold surface (9) of the mold (8). When the filled heat-sensitive adhesive layer (10) is solidified, it has a smooth surface as shown in FIG. Film (11) with mold (9)
A mold (13) stuck on the mold is obtained.

[Example 3] As shown in Fig. 9, the mold (7) prepared in Example 1 was used as a gate (15) or sand (14) with a runner or the like.
After being immersed in the mold, when a molten aluminum material melted at 720 ° C. is injected through the gate (15), the mold is made of the thermoplastic foam and adhered on the mold surface. The film (3) having the heat-sensitive adhesive layer (4) on its back surface is shrunk and decomposed by the heat of the molten metal and removed, and the casting surface obtained by cooling and solidifying the injected metal melt forms a molding die ( 7) The part of the surface of the casting (3) in contact with the smooth film (3) is completely smooth, and the other part of the casting surface in contact with the mold surface (2) of the molding die (7) results in irregularities of the foam. As a result, irregularities are formed.

Example 4 The molding die (13) prepared in Example 2 was immersed in sand (16) to which a gate (17) was attached as shown in FIG. When the casting of the melt is molded, the part of the mold (13) in contact with the smooth film (11) becomes completely smooth, and the part in contact with other parts is attributed to the unevenness of the foam. Irregularities are formed.

[Brief description of the drawings]

1 to 4 show Example 1. FIG. 1 is a side view of a molding base, FIG. 2 is a side view of a molding base obtained by polymerizing a film, and FIG. 4 is a side view of a molding die, and FIGS. 5 to 8 show a second embodiment.
FIG. 6 is a perspective view of a molding die, FIG. 6 is a perspective view of a film, FIG. 7 is a side sectional view of a molding die obtained by polymerizing a film, FIG. 8 is a perspective view of the molding die, and FIG. FIG. 10 is a cross-sectional view of a molding state when using a molding die prepared according to Example 2, and FIG. In the figure, (1), (8) ... molding base mold, (2), (9) ...
... mold surface, (3), (11) ... film, (3A) ... composite film, (4), (10) ... heat-sensitive adhesive layer, (12)
…… Composite film molding, (7), (13) …… Mold

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Harumi Ueno 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tokiharu Fukuda 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Shunichi Fujio 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-51-130629 (JP, A) JP-A-58-100940 (JP, A)

Claims (1)

(57) [Claims] 1. A film (B) made of a heat-fusible, flammable or soluble material having a smooth surface and a film (B) formed on a mold surface of a mold (A) made of a thermoplastic plastic foam. )), A composite film (D) comprising the mold (A) and the heat-sensitive adhesive layer (C) having a lower melting point than the material constituting the film (B) is polymerized. The composite film (D) is heat-pressed to a temperature not lower than the melting point of the heat-sensitive adhesive layer (C) and not higher than the melting points of the mold (A) and the film (B). A molding die, comprising: pressing the film (D) on the die surface of the die (A); and filling the heat-sensitive adhesive layer (C) into irregularities on the die surface of the die (A). Manufacturing method