JP2986879B2 - Manufacturing method of precision casting mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the invention]

(Industrial application field) The present invention relates to a method for producing a precision casting mold used for producing a precision casting mold used for producing a precision casting. (Prior art) There are various types of precision casting methods for producing precision castings, such as centrifugal casting, die casting, low-pressure casting, and shell-type methods, as well as methods using vanishing models. There is a method of using a wax model or a urea resin model as a way to form a casting space by causing the disappearing model to disappear before pouring the molten metal, and to eliminate the disappearing model made of expanded polystyrene while pouring the molten metal. As a casting method, there is a full mold method and the like. ("Revised 4th edition metal handbook"
Published on December 20, 1982 by The Japan Institute of Metals No. 15
Page 14-1527, "13.5 Special casting method"). Further, as a method for precision casting of a complicated-shaped part having an undercut, there has been a method using a resin vanishing model created by applying stereolithography. (Problems to be Solved by the Invention) However, in the case of using such a resin model, since the high-temperature disappearance method and the autoclave method were employed at the time of demolding due to the disappearance of the resin, thermal expansion was performed at the time of demolding. When applied to a normal shell coating mold, it may cause cracks or breakage in this mold, so it may be necessary to use a solid mold. In order to prevent cracking or breakage of the mold due to thermal expansion of the model, it was necessary to strengthen the mold, including shell-coated molds and solid molds. Therefore, there is a problem that the thickness of the mold increases, the weight of the mold increases, a long time is required for sintering, the air permeability of the mold decreases, and casting defects such as poor running of the melt easily occur. In addition, there is a problem that the mold is so strong that it is difficult to separate the mold after casting, and it has been a problem to solve these problems. (Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and it is necessary to perform heating upon disappearance of the resin model of a precision casting mold manufactured using the resin model. Therefore, there is no possibility that cracks or breakage will occur in the precision casting mold due to thermal expansion of the disappearing model, and it is not necessary to strengthen the precision casting mold to prevent cracking and damage as in the conventional case. Precise casting molds that can obtain precision casting products without casting defects without requiring a long time for sintering or reducing air permeability due to increase in thickness or weight increase It is intended to be able to manufacture.

Configuration of the Invention

(Means for Solving the Problems) In the present invention, when producing a precision casting mold using a disappearing model, a water-soluble ultraviolet-curable resin containing methoxylated polyethylene glycol acrylate is used for the disappearing model. It is characterized by having a configuration,
The configuration of such a method of manufacturing a precision casting mold is a means for solving the above-mentioned conventional problems. The method for manufacturing a precision casting mold according to the present invention has the above-described configuration, and as a material for the disappearing model,
Using a water-soluble UV-curable resin containing methoxylated acrylate of polyethylene glycol, for example,
A vanishing model is manufactured by irradiating a laser beam or the like with a three-dimensional lithographic apparatus and curing, and a solid mold is manufactured using this vanishing model, or a shell coating mold is manufactured. The casting space is to be formed by dissolving part or all of the casting space. In the method for manufacturing a precision casting mold according to the present invention, a water-soluble UV-curable resin containing methoxylated polyethylene glycol acrylate is used as a material for the disappearing model. A resin that cures in a relatively short time (eg, in seconds) due to the chemical action of ultraviolet light.
It is composed of a prepolymer (also called an oligomer), a photopolymerization initiator, a stabilizer and the like. Generally, monomers and prepolymers have acryloyl groups (CH ₂ CHCH—CO) and methacryloyl groups (C
_{H 2 = C (CH 3)} CO-), a vinyl group (CH ₂ = CH-), having one or several photopolymerizable functional groups such as carboxyl group (-COOH), a hydroxy group (-OH) And those containing unsaturated bonds in the molecular chain, such as polybutadiene and unsaturated polyester. A typical example of the former monomer is 2
-Ethylhexyl, 2-hydroxyethyl acrylate, 2
Monofunctional ones such as hydroxyethylacryloyl phosphate, tetrahydrofurfuryl acrylate, 1,4-butanediol diacrylate, 1,6-hexiondiol diacrylate, diethylene glycol diacrylate, polyethylene glycol 400 diacrylate, trimethylol There are multifunctional ones such as propane triacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate. Examples of the latter prepolymer include polyester acrylate, epoxy acrylate, and polyurethane acrylate. Further, the photopolymerization initiator is one that initiates the polymerization reaction by absorbing ultraviolet light or a laser beam having a wavelength similar to the ultraviolet light, and has an ultraviolet region of 300 to 450 nm (nanometer), Chemical structures include carbonyl compounds, sulfur compounds, azo compounds, and organic peroxides. Biacetyl, acetophenone, benzophenone,
Benzyl, benzoin, benzoyl peroxide, methylbenzoyl formate and the like. In some cases, amines such as triethylamine and diethylaminomethacrylate are used as a sensitizer of a photopolymerization initiator by ultraviolet rays or laser beams. A composition using the above-described monomer or prepolymer forms a cured product by irradiation with ultraviolet light or laser light, but in this state, shows a property insoluble in water. The water-soluble UV-curable resin used in the present invention is a liquid-state composition, which is cured in a short time (for example, in seconds) by irradiation with ultraviolet rays or a laser beam to form a model and form a mold. It must be soluble in water later. The composition used in the present invention is obtained by methoxylating acrylate of polyethylene glycol, for example, methoxy polyethylene glycol acrylate [CH
_{2 = CH-CO- (OCH 2} -CH 2) n-OCH 3], or They have been found to be photopolymerizable and soluble in water. In the present invention, the above-mentioned compounds can be used alone, but in addition, a combination with a water-soluble resin such as polyvinyl alcohol, polyvinylpyrrolidone, a water-soluble resin soluble in the above composition, and photopolymerization initiation As the agent, those listed above can be used. (Effect of the Invention) In the method for producing a precision casting mold according to the present invention, in producing a precision casting mold using a disappearing model, a water-soluble solution containing a methoxylated polyethylene glycol acrylate in the disappearing model is used. Since it is configured to use an ultraviolet curable resin, the disappearing model is eluted by contacting with water when performing demolding after manufacturing a precision casting mold such as a solid mold or shell coating mold using the disappearing model. Since the model is removed from the model, the thermal expansion of the disappearing model does not occur as in the case of removing the model by heating.Therefore, there is no possibility of cracking or damage of the precision casting mold due to the thermal expansion of the disappearing model. As a result, a high-quality precision casting having no casting defects due to a sound precision casting mold can be obtained. (Example) Next, an example of a method for manufacturing a precision casting mold according to the present invention will be described with reference to the accompanying drawings. In this embodiment, a case in which a casting mold for precision casting is manufactured using the vanishing model 1 having the shape shown in FIG. 1 will be described as an example. First, when manufacturing the vanishing model 1 having the shape illustrated in FIG. 1, a water-soluble ultraviolet-curing resin 3 housed in a container 2 was prepared as shown in FIG. 2 (a). This water-soluble UV-curable resin has the compounding ratio shown in Table 1 and has the properties shown in Table 2. Then, as shown in FIG. 2 (a), after the molding plane 4a of the elevating body 4 is placed at a position sinking by Δh from the surface of the water-soluble UV-curable resin 3 contained in the container 2,
Production of the vanishing model 1 by three-dimensional lithography in which He-Cd laser light 5 of 325 nm is irradiated at a desired amplitude is started. As a result, as shown in FIG.
After forming one flange portion 1a of the disappearance model 1 shown in FIG. 1 by curing the water-soluble ultraviolet curing resin 3 on 4a, the amplitude of the laser beam 5 is increased as shown in FIG. 2 (b). The shaft portion 1b of the vanishing model 1 is formed by gradually irradiating the ring and lowering the elevating body 4 little by little, and the irradiation of the laser beam 5 and the lowering of the elevating body 4 are continued to form the second part. As shown in FIG. 5C, the shaping of the shaft portion 1b is continued, and after the shaft portion 1b having the desired height is formed, the laser beam 5
2d by forming the other flange portion 1c of the vanishing model 1 by increasing the amplitude again.
As shown in (1), a vanishing model 1 made of a water-soluble ultraviolet curable resin is obtained on the molding surface 4a of the elevating body 4. When manufacturing a precision casting mold using such a lost model 1, as shown in FIG. 3 (a), two lost models 1, a wax gate 6 and a runner 7 also made of wax are used. After assembling, Fig. 3 (b)
As shown in FIG. 3, refractory slurry coating is performed by dipping in a refractory slurry 8, and then, as shown in FIG. After the required refractory thickness is obtained by repeating coating and sanding, the disappearance model 1 is eluted and removed by immersion in water 10 as shown in FIG. The sprue (6) and the runner (7) are formed by performing the dewaxing, and at the same time, as shown in FIG. . Next, the precision casting mold 11 manufactured in this manner was intentionally destroyed, and the state of the casting space inner surface was observed.As a result, a sound precision casting mold free from defects such as cracks was found. Admitted. In the method for producing a precision casting mold according to the present invention, since the stress due to the thermal expansion of the disappearing model is not applied to the precision casting mold during the demolding of the disappearing model, a shell coating mold having a relatively small thickness and good air permeability is used. It is suitable for the production of solid molds, but may be applied to the production of solid molds.

【The invention's effect】

The present invention is based on the use of a water-soluble ultraviolet-curable resin including a methoxylated polyethylene glycol acrylate as the disappearing model when manufacturing a precision casting mold using the disappearing model. When demolding is performed after manufacturing a precision casting mold such as a solid mold or shell coating mold using the above, the disappearing model is eluted and demolded by adopting means for contacting with water such as water immersion. Therefore, the thermal expansion of the disappearing model does not occur at all as in the case of removing the model by conventional heating, and therefore, cracks or damage on the inner surface of the casting space part of the precision casting mold due to the thermal expansion of the disappearing model Mold to prevent cracks and breakage when the disappearance model is lost by heating as in the past. It is not necessary to increase the mold thickness because it needs to be stronger, and problems such as prolonged firing and reduced air permeability due to the increase in mold thickness are eliminated. This has a remarkably excellent effect that a precise casting can be manufactured.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a slope illustrating the shape of a vanishing model used for manufacturing a precision casting mold, and FIGS.
(D) is an explanatory view sequentially showing the steps of manufacturing the vanishing model shown in FIG. 1, and FIGS. 3 (a), (b), (c), (d) and (e) use the vanishing model shown in FIG. It is explanatory drawing which shows the process of manufacturing a casting mold for precision casting sequentially. 1 ... vanishing model, 11 ... mold for precision casting.

Continuation of the front page (56) References JP-A-54-15417 (JP, A) JP-A-60-247440 (JP, A) JP-A-54-148128 (JP, A) JP-A-2-52725 (JP) , A) JP-A-3-174943 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22C 7/00-7/02

Claims (1)

(57) [Claims] 1. A precision casting mold for producing a precision casting mold using a vanishing model, characterized in that a water-soluble ultraviolet curing resin containing methoxylated polyethylene glycol acrylate is used for the vanishing model. Manufacturing method of mold.