JP2004181472A - Mold and structural body for producing casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold and a structural body for producing a casting, having good formability and light weight and sufficient hot-strength and shape-holding property at the casting time and excellent surface smoothness of the casting and excellent removability after casting. <P>SOLUTION: This mold and structural body includes an organic fiber, an inorganic fiber and a thermosetting resin. It is desirable that the above organic fiber is a paper fiber and the above inorganic fiber is a carbon fiber and the above thermosetting resin is a phenolic resin. A blending ratio of the above organic fiber, inorganic fiber and thermosetting resin is desirably 10-70/1-80/10-70 (weight ratio). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００７９】
表１に示すように、実施例１〜６では、鋳型等の成形性も良好であり、軽量で、比較例６と同等以上に鋳込み後の鋳型等の形状保持性および表面平滑性も良好であった。さらに、抄造後の鋳型等の除去性も実施例１〜６の何れも良好であった。これに対し、比較例１〜３、５では、鋳型等は成形できるものの、熱間強度が劣るため、当該鋳型等を使用して鋳物を鋳造しても、得られる鋳物の形状保持性、表面平滑性は悪かった。特に、比較例４では、鋳型等の製造自体が困難であった。
【００８０】
【発明の効果】
本発明によれば、以下の効果が奏される。
１．本発明の鋳物製造用の鋳型及び構造体は、成形性がよく、表面の平滑性に優れ、且つ鋳込み時においてもこれを保持できる。このため、これを用いた鋳物の製造方法では、得られる鋳物の表面平滑性を高めることができる。特に従来のような塗型剤を施さなくても、鋳造後の焼着が大幅に低減できるため、鋳物の製造工数低減を図ることができる。
２．本発明の鋳物製造用の鋳型及び構造体は、鋳込み時においても熱間強度及び形状保持性に優れる。このため、これを用いた鋳物の製造方法では、造型の際に鋳物砂をバインダーで硬化させる必要がない。従って、鋳造後に機械的研磨により砂を再生する必要がなく、従来に比べて廃棄物を低減できる。また、特に、中空形状の中子に適用する場合でも、中子内への鋳物砂の充填が必ずしも必要でない。
３．本発明の鋳物製造用の鋳型及び構造体は、鋳込み後の除去性が良好であり、従来に比べて容易に鋳型等を除去することができる。
４．本発明の鋳物製造用の鋳型及び構造体は、軽量であるため、取り扱いが容易である。
５．本発明の鋳物製造用の鋳型及び構造体の製造方法では、有機繊維、無機繊維を含む原料スラリーを抄造して製造するので、各成分がむらなく均一に分散した鋳型等を得ることができる。従って、熱収縮に伴うひび割れ等の発生が抑えられ、高い熱間強度が得られ、表面の平滑性にも優れている。また、中空形状や複雑な立体形状とする場合にも貼り合わせ工程が不要なので、最終的に得られる鋳型等の肉厚が均一で成形精度や機械的強度が高く、成形精度の高く表面の平滑性に優れた鋳物を製造することができる。
【図面の簡単な説明】
【図１】本発明の鋳物製造用鋳型等を中空中子に適用した一実施形態を用いて製造された鋳物を模式的に示す斜視図である。
【図２】前記実施形態の中空中子を用いて製造された鋳物を模式的に示す斜視図である。
【符号の説明】
１ 中空中子（鋳型等）
１０ 鋳物[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold or structure (hereinafter referred to as “mold or structure” also referred to as a mold or the like) used in the production of a casting, a method for producing the mold, and a method for producing a casting using the mold or the like.
[0002]
[Prior art and problems to be solved by the invention]
For castings, in general, a mold having a cavity is formed with casting sand based on a wooden mold or a mold, and a core is disposed in the cavity as needed, and then a molten metal is supplied to the cavity. Manufactured.
[0003]
The manufacture of wooden molds and molds requires skill in processing and expensive equipment, and there are disadvantages such as expensive and heavy disposal, as well as disposal problems, making it difficult to use in addition to mass-produced castings. Moreover, since the sand mold | die using casting sand has added the binder to normal sand, it is made to harden | cure and the shape is hold | maintained, a recycling process process becomes essential for reuse of sand. There is also a problem that waste such as dust is generated during the regeneration process. In addition, when the core is manufactured in a sand mold, it is difficult to handle due to the weight of the core itself in addition to the above problems, and furthermore, there are conflicting performances of strength maintenance during casting and core removal after casting. Required.
[0004]
As a technique for solving such problems, for example, a member used for a mold is formed of an organic fiber material such as paper (see Patent Document 1 below), an inorganic fiber is a main component, and a resin is used as a binder. Addition and molding (see Patent Document 2 below), or addition and molding of cellulose fibers with inorganic powder or inorganic fiber (see Patent Document 3 below) are known.
[0005]
Although these technologies have some effects in terms of weight reduction, workability, and waste material problems, 1) it is difficult to obtain a uniform molded body, and in particular, formability when uniformly forming into a hollow structure. And 2) the hot strength is low, the shape retention of the casting after casting cannot be sufficiently obtained, and 3) the surface smoothness of the resulting casting is low. For this reason, means that can improve these problems has been strongly desired.
[0006]
[Patent Document 1]
Japanese Utility Model Publication No. 6-86843
[Patent Document 2]
Japanese Patent Laid-Open No. 10-5931
[Patent Document 3]
Japanese Patent Laid-Open No. 9-253792
[0007]
Therefore, the object of the present invention is good moldability such as molds, light weight, sufficient hot strength and shape retention even at the time of casting, excellent shape retention and surface smoothness of the resulting casting, Furthermore, it is providing the casting_mold | template and structure for castings excellent in the removability after casting, these manufacturing methods, and the manufacturing method of castings using these.
[0008]
[Means for Solving the Problems]
This invention achieves the said objective by providing the casting_mold | template or structure for casting manufacture containing an organic fiber, an inorganic fiber, and a thermosetting resin. In the present specification, the term “structure for casting production” may be included in the category of “mold for casting production”.
[0009]
Further, the present invention is a method for producing a casting mold or structure for producing a casting according to the present invention, wherein the casting mold or structure includes a papermaking process using a raw slurry containing at least the organic fiber and the inorganic fiber. The object is achieved by providing a method for manufacturing a structure.
[0010]
Moreover, this invention achieves the said objective by providing the manufacturing method of the casting using the casting_mold | template or structure for casting manufacture of the said invention.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on preferred embodiments thereof.
[0012]
The mold of this embodiment contains organic fibers, inorganic fibers, and a thermosetting resin.
The mixing ratio of the organic fiber, the inorganic fiber, and the thermosetting resin is the organic fiber / the inorganic fiber / the thermosetting resin = 10 to 70/1 to 80/10 to 70 (weight ratio), and It is preferable that it is 10-50 / 5-50 / 20-70 (weight ratio), especially 10-30 / 10-40 / 30-60 (weight ratio).
[0013]
If the organic fiber is less than 10 in the blending ratio, the addition effect cannot be obtained, and the moldability of the mold and the removability of the mold after casting may be deteriorated. When the blending ratio exceeds 70, There are cases where the amount of gas generated during casting increases and surface defects of the casting are likely to occur, heat resistance is lowered, and shape retention of the casting is lowered.
[0014]
In addition, if the inorganic fiber is less than 1 in the blending ratio, the shape retention of the casting may be reduced due to heat shrinkage due to a decrease in heat resistance of the mold or the like, or the amount of gas generated may be increased. If the ratio exceeds 80, the moldability of the mold and the like is deteriorated, and the removability of the mold and the like after casting may be lowered.
[0015]
Furthermore, if the thermosetting resin is less than 10 in the blending ratio, the surface smoothness of the casting may not be obtained, and the strength and shape retainability of the mold may be deteriorated. In addition to the poor formability, the amount of gas generated increases and surface defects of the casting are likely to occur.
[0016]
The organic fiber is a component that forms a skeleton in a state before being used for casting mainly in a mold or the like and improves moldability of the mold or the like. Further, when used for casting, it is a component that part or all of it is burned by the heat of the molten metal, forming voids in the mold after the casting is manufactured, and improving the removability of the mold.
[0017]
Examples of the organic fibers include paper fibers, fibrillated synthetic fibers, and recycled fibers (for example, rayon fibers). These organic fibers can be used alone or in combination of two or more. Among these, it is particularly preferable to use paper fibers because they can be formed into various forms by papermaking and sufficient strength can be obtained after dehydration and drying.
[0018]
Examples of the paper fiber include wood pulp, cotton pulp, linter pulp, bamboo straw and other non-wood pulp. As the paper fiber, these virgin pulp or waste paper pulp can be used alone or in combination of two or more. The paper fiber is particularly preferably used paper pulp from the viewpoints of easy availability, environmental protection, and reduction of manufacturing costs.
[0019]
The organic fiber preferably has an average fiber length of 0.3 to 2.0 mm, particularly 0.5 to 1.5 mm in consideration of moldability such as a mold, surface smoothness, and impact resistance.
[0020]
The blending ratio of the organic fiber in the mold or the like is preferably 10 to 70 wt%, particularly 10 to 50 wt% in consideration of moldability of the mold or the like and removability of the mold or the like after manufacturing the casting.
[0021]
The inorganic fiber is a component that mainly forms a skeleton in a state before being used for casting in a mold or the like, and maintains its shape without being burned by the heat of molten metal when used for casting. In particular, it is a component that suppresses thermal shrinkage caused by thermal decomposition of an organic component such as a thermosetting resin used in the present invention by the heat of molten metal.
[0022]
Examples of the inorganic fibers include artificial mineral fibers such as carbon fibers and rock wool, ceramic fibers, and natural mineral fibers. These inorganic fibers can be used alone or in combination of two or more. Among these, it is preferable to use pitch-based or polyacrylonitrile (PAN) -based carbon fibers having high strength even at high temperatures from the viewpoint of effectively suppressing shrinkage associated with carbonization of the thermosetting resin, and in particular, PAN-based carbon. Fiber is preferred.
[0023]
The inorganic fibers preferably have an average fiber length of 0.2 to 10 mm, particularly 0.5 to 8 mm, from the viewpoints of dewaterability when paper is made from a mold or the like and dewatered, moldability of the mold or the like, and uniformity. .
[0024]
Moreover, the said inorganic fiber is represented by the following formula when it heat-processes for 10 minutes in 1000 degreeC and reducing atmosphere (nitrogen atmosphere) from the point which suppresses the thermal contraction accompanying the thermal decomposition of a thermosetting resin effectively. The shrinkage ratio is preferably 5% or less, more preferably 3% or less, and particularly preferably 2% or less.
Shrinkage rate = (sheet length before treatment−sheet length after heating) × 100 / (sheet length before heating)
Here, the sheet length is 50 mm in length produced in the same manner as in wet papermaking in Examples described later with a blending ratio of newspaper / inorganic fiber / novolak phenol resin = 25 / 37.5 / 37.5 (weight ratio). A sheet having a width of 50 mm and a thickness of 1 mm is used as a sample, and the average value of the vertical and horizontal dimensions is used.
[0025]
The inorganic fiber is preferably blended in an amount of 10 to 300 parts by weight, particularly 20 to 200 parts by weight, based on 100 parts by weight of the organic fiber in the blending ratio. By blending the inorganic fiber in such a range, the heat resistance of the mold or the like can be sufficiently maintained, and the occurrence of casting surface defects due to gas generation can be suppressed.
[0026]
Examples of the thermosetting resin include thermosetting resins such as phenol resins, epoxy resins, and furan resins. The thermosetting resin is a component necessary for maintaining the normal temperature strength and the hot strength and improving the surface roughness of the casting, and a surface smoothness equivalent to that of a sand mold coated with a coating agent is obtained. It is not necessary to use a coating agent. Such performance is important for the mold of the present invention containing organic fibers and the like that are difficult to ignite and dry when using conventional alcoholic coating agents.
[0027]
In particular, the thermosetting resin having such performance has little generation of combustible gas, has a combustion suppressing effect, has a high residual carbon ratio of 25% or more after pyrolysis (carbonization), and has a carbon film at the time of casting. It is preferable to use a phenol-based resin from the viewpoint that a good casting surface can be obtained for the formation. The residual carbon ratio can be determined from the residual weight after heating to 1000 ° C. in a reducing atmosphere (under a nitrogen atmosphere) by an analytical thermal analysis.
[0028]
Examples of the phenolic resin include novolak phenol resins, resol type phenol resins, modified phenol resins modified with urea, melamine, epoxy, and the like, preferably novolak phenol resins or modified resins thereof.
[0029]
The thermosetting resins may be used alone or in combination of two or more, and may be used in combination with an acrylic resin, a polyvinyl alcohol resin, or the like. In particular, when the mold of the present invention is applied to a hollow core, a high hot strength can be obtained by using a thermosetting resin (particularly a residual carbon ratio of 15% or more, particularly 25% or more). Therefore, the function as a hollow core can be sufficiently exhibited.
[0030]
The thermosetting resin is preferably blended in an amount of 50 to 400 parts by weight, particularly 70 to 300 parts by weight, per 100 parts by weight of the organic fiber in the blending ratio. By blending the curable resin in such a range, the surface roughness and shape retention of the casting can be improved.
[0031]
The thermosetting resin is coated on the organic fiber or inorganic fiber, or powdered or emulsified and added to the raw material slurry, and the organic fiber and the inorganic fiber are combined when made into a dry slurry after paper making. Maintaining the strength of molds, etc. by carbonizing with the heat of the molten metal at the time of casting, etc. As long as it can contribute to the improvement of the surface smoothness of the casting, any form may be included.
[0032]
Since the curing agent required when the novolak phenol resin is used is easily dissolved in water, it is preferably applied after dehydration of the molded body, particularly in the case of wet papermaking. It is preferable to use hexamethylenetetramine or the like as the curing agent.
[0033]
In addition to the organic fiber, the inorganic fiber, and the thermosetting resin, the mold of the present embodiment includes a carburizing inhibitor such as obsidian and mullite powder, polyvinyl alcohol, carboxymethylcellulose (CMC), polyamide, as necessary. Other components such as a paper strength reinforcing material such as an amine epichlorohydrin resin, a polyacrylamide-based flocculant, and a colorant can be added at an appropriate ratio.
[0034]
The thickness of the mold or the like of the present embodiment can be appropriately set according to the portion to be used, but at least the thickness at the portion in contact with the molten metal is 0.2 to 5 mm, particularly 0.4 to 2 mm. Is preferred. If it is too thin, the strength required when casting with casting sand will be insufficient, and the shape function of the structure such as the mold, especially the core, may not be maintained. In addition to the increased surface defects of the casting, the molding time may be increased and the manufacturing cost may be increased.
[0035]
In the state before being used for casting, the mold or the like of the present embodiment preferably has a bending strength of 5 MPa or more, and more preferably 10 MPa or more.
[0036]
When the mold of the present embodiment is manufactured through a paper making process using a raw material slurry using water as a dispersion medium, the moisture content in the state before being used for casting from the point of suppressing the amount of gas generation during casting as much as possible. (Weight moisture content) is preferably 10% or less, particularly preferably 8% or less.
[0037]
The mold and the like of the present embodiment preferably have a specific gravity of 1.0 or less in the state before being used for casting in terms of lightness and ease of molding and secondary processing. More preferably, it is 8 or less.
[0038]
The mold and the like of the present embodiment can be applied to a main mold having a cast product-shaped cavity on the inner surface, a core used in the main mold, or a pouring system member such as a runner, Since the mold of the present invention is excellent in surface smoothness and a casting having a good casting surface can be obtained, application to a main mold and a core is preferable. In particular, it has excellent hot compressive strength, high shape-retaining properties, and excellent removability after casting. It is preferable to apply to a hollow core that does not require filling.
[0039]
When the mold of this embodiment is used for the production of a casting, it is not always necessary to harden the foundry sand to be filled around the main mold and the foundry sand to be filled in the hollow core for backup purposes with a binder. Therefore, there is an advantage that the casting sand can be easily regenerated.
[0040]
Next, the manufacturing method of the casting_mold | template etc. of this invention is demonstrated based on the preferable embodiment.
In the manufacturing method of this embodiment, a raw material slurry containing the organic fiber, the inorganic fiber, and the thermosetting resin at the predetermined blending ratio is prepared, and a fiber laminate having a predetermined shape is obtained by a wet papermaking method using the raw material slurry. Paper, and then dehydrated and dried to produce molds.
[0041]
Examples of the dispersion medium of the raw material slurry include water, white water, and solvents such as ethanol and methanol. Among these, from the viewpoints of papermaking / dehydration stability, quality stability, cost, ease of handling, etc. Water is particularly preferable.
[0042]
The total ratio of the fibers to the dispersion medium in the raw slurry is preferably 0.1 to 3 wt%, particularly 0.5 to 2 wt%. If the total proportion of the fibers in the raw material slurry is too large, uneven thickness tends to occur. In particular, in the case of a hollow product, the surface property of the inner surface may be deteriorated. Conversely, if the amount is too small, a local thin portion may occur.
[0043]
If necessary, additives such as the carburizing inhibitor, the paper strength reinforcing material, the flocculant, and the preservative can be added to the raw slurry at an appropriate ratio.
[0044]
In the paper making process of the fiber laminate, for example, a cavity having a shape substantially corresponding to the outer shape of the mold or the like and opening to the outside is formed inside by matching a pair of split molds. Use the mold to be formed. Each split mold is provided with a large number of communication holes for communicating the outside with the cavity, and the inner surface of each split mold is covered with a net having a mesh of a predetermined size. Then, a predetermined amount of raw material slurry is injected into the cavity of the mold using a pressure pump or the like, while liquid is sucked and discharged through the communication hole, and the solid content of the raw material slurry is deposited on the net. The pressure for pressure injection of the raw slurry is preferably 0.01 to 5 MPa, particularly preferably 0.01 to 3 MPa.
[0045]
When a fiber laminate having a predetermined thickness is formed on the net by injecting a predetermined amount of raw material slurry, the pressure injection of the raw material slurry is stopped, and air is injected into the cavity so that the fiber laminate has a predetermined water content. Dehydrate to rate.
[0046]
Next, the fiber laminate is dry-molded. In this dry molding process, a dry mold having a shape corresponding to the outer shape of a mold or the like to be molded by abutting a set of split molds and having a cavity that opens outward is used. Then, the drying mold is heated to a predetermined temperature, and the dehydrated fiber laminate is loaded into the drying mold.
[0047]
Next, an elastic, elastic and hollow core (elastic core) is inserted into the cavity, a pressurized fluid is supplied into the core, and the core is inserted into the cavity. Inflate. Then, the fiber laminate is pressed against the formation surface of the cavity and dried while transferring the shape of the inner surface of the cavity. For the core, for example, urethane, fluorine rubber, silicone rubber or elastomer is used.
[0048]
Examples of the pressurized fluid for expanding the core include compressed air (heated air), oil (heated oil), and other various liquids. The pressure for supplying the pressurized fluid is preferably 0.01 to 5 MPa, particularly preferably 0.1 to 3 MPa.
[0049]
The heating temperature (mold temperature) of the drying mold is preferably 180 to 250 ° C., particularly 200 to 240 ° C. in consideration of drying time and deterioration of surface properties due to scorching.
[0050]
After the fiber laminate is dried, the pressurized fluid in the core is drained, the core is shrunk and removed from the fiber laminate. Then, the dry mold is opened, and a dry-molded mold or the like is taken out.
[0051]
The obtained mold or the like can be partially or wholly impregnated with a binder and heated to be thermally cured as necessary. Examples of the binder include colloidal silica, ethyl silicate, and water glass.
[0052]
The molds obtained in this manner have organic fibers, inorganic fibers, and thermosetting resin components evenly dispersed, so that the occurrence of cracks associated with thermal shrinkage is suppressed, and high hot strength And the surface smoothness is also excellent. Moreover, since the said fiber laminated body is pressed and shape | molded from the inside to the formation surface of the dry type cavity with the said core, the smoothness of an inner surface and an outer surface is high. For this reason, when it uses for manufacture of a casting, the obtained casting becomes a thing excellent especially in surface smoothness. In addition, when a hollow shape or a complicated three-dimensional shape is used, since a bonding step is not required, the finally obtained mold or the like does not have a seam and a thick portion due to bonding. Also in this respect, it is possible to manufacture a casting having a uniform thickness, high molding accuracy and mechanical strength, high accuracy, and excellent surface smoothness. Therefore, the present invention can be applied not only to the main mold and the core but also to the manufacture of a structure such as a runner having a fitting part and a screw part.
Moreover, when there is a concern about the occurrence of gas defects due to the material and shape of the casting, the mold or the like may be heat-treated at 200 to 250 ° C. in a reducing atmosphere in advance.
[0053]
Next, the manufacturing method of the casting of this invention is demonstrated based on the preferable embodiment.
In the manufacturing method of the present embodiment, the predetermined mold or the like obtained as described above is embedded in a predetermined position in the foundry sand to make a mold. As the foundry sand, a conventional one that has been conventionally used for producing this type of casting can be used without any particular limitation. The foundry sand need not be cured with a binder, but may be cured as necessary. When the mold or the like is a hollow core, the core does not need to be filled with foundry sand, but can be filled.
[0054]
Then, the molten metal is poured from the pouring gate and cast. At this time, although the thermosetting resin and the organic fiber are pyrolyzed and carbonized, the inorganic fiber suppresses thermal shrinkage accompanying the thermal decomposition. For this reason, there is almost no occurrence of cracks in each mold or the like, or the mold itself is damaged, and there is hardly any insertion of molten metal into the mold or the like, or adhesion of foundry sand or the like. Moreover, since the surface smoothness of a casting mold etc. is maintained by the carbonized film produced | generated by the said thermal decomposition, the surface smoothness of the casting obtained also becomes favorable.
[0055]
After the casting is finished, the casting is cooled to a predetermined temperature, the casting frame is disassembled to remove the foundry sand, and the casting mold is removed by blasting to expose the foundry. At this time, since the organic fiber is thermally decomposed, the removal process of the mold and the like is easy. Then, post-processing such as trimming is performed on the casting as necessary to complete the casting.
[0056]
The casting production method of the present embodiment uses the mold including the organic fiber, the inorganic fiber, and the thermosetting resin, so that the hot strength can be maintained by the inorganic fiber and the thermosetting resin. A casting having excellent dimensional accuracy and surface smoothness can be produced. In addition, the removal of the mold and the like can be easily performed by forming a void in the mold and the like by pyrolysis of the organic fiber, etc. The amount of waste generated can be significantly reduced, and the processing effort can be greatly reduced. Furthermore, since it is not always necessary to harden the foundry sand with a binder, the reclaiming treatment of the foundry sand becomes simple.
[0057]
The present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.
[0058]
The mold of the present invention, as in the above-described embodiment, forms a three-dimensional hollow mold or the like, and forms a molded body by a wet papermaking method, and manufactures the mold or the like through dehydration and dry molding processes. It is preferable, however, that the raw material slurry is made into a paper to form a sheet-like molded body, and this is rolled up as a paper tube to produce a mold or the like.
[0059]
In addition, it is preferable to produce a mold or the like corresponding to the final shape after dry molding. However, the molded body obtained after drying is cut and divided, and the divided parts are fitted or screwed together. It can also be manufactured in a form that can be connected together. In this case, it is preferable to form in advance a form having a fitting or screwing portion at the end or divided portion.
[0060]
The casting production method of the present invention can be applied to casting of non-ferrous metals such as aluminum and its alloys, copper and its alloys, nickel, lead, etc. in addition to molten metal (cast iron).
[0061]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
[0062]
Molds having the material composition shown in Table 1 were prepared as in Examples 1 to 6 and Comparative Examples 1 to 5 below, and the weights of the obtained molds were measured, and the moldability of the molds and the like was as follows: Evaluated. Further, a casting was produced using the obtained mold and the like, and the shape retention of the casting (shape retention of the mold and the like), the surface smoothness and the removability of the mold after casting were evaluated as follows. The results are shown in Table 1.
[0063]
[Example 1]
<Preparation of raw material slurry>
After preparing a slurry of about 1 wt% in which the following organic fibers and inorganic fibers are dispersed in water with the formulation shown in Table 1, the following thermosetting resin powder and an appropriate amount of the following flocculant are added to the slurry, and the raw material slurry Adjusted.
Organic fiber: used newspaper (average fiber length 1mm, freeness (CSF, the same applies below) 150cc)
Inorganic fiber: PAN-based carbon fiber (“Toray Chop” manufactured by Toray Industries, Inc., fiber length 3 mm, shrinkage 0.1%)
Thermosetting resin: Novolac phenolic resin ("SP1006LS" manufactured by Asahi Organic Materials Co., Ltd., residual charcoal rate 38%)
Flocculant: Polyacrylamide flocculant (“A110” manufactured by Mitsui Cytec)
[0064]
<Making of molds, etc.>
The papermaking mold is a pair of split molds having a cavity forming surface corresponding to φ40 × 100 mm, a net having a predetermined mesh is arranged on the cavity forming surface, and a large number of communication holes communicating the cavity forming eyes with the outside What was formed was used. Then, the raw material slurry was circulated by a Mono pump, and a predetermined amount of slurry was pressurized and injected into the papermaking mold, while drained through the communication hole, and a predetermined fiber laminate was deposited on the surface of the net. After the injection of a predetermined amount of raw material slurry was completed, 0.2 MPa of pressurized air was supplied for about 30 seconds into the papermaking mold on which the fiber laminate was deposited, and the fiber laminate was dehydrated. A liquid in which a 15% (weight ratio) curing agent (hexamethylenetetramine) of the thermosetting resin was dispersed in water was uniformly applied to the entire surface of the obtained fiber laminate. The fiber laminate was then removed from the papermaking mold and transferred to a dry mold heated to 220 ° C. The drying mold used was a pair of split molds having a cavity forming surface corresponding to φ40 × 100 mm, in which a large number of communication holes communicating the cavity forming surface and the outside were formed. In the drying process, a bag-shaped elastic core is inserted from the upper opening of the drying mold, and pressurized fluid (pressurized air, 0.2 MPa) is supplied into the elastic core in the sealed drying mold. Then, the elastic core was inflated. Then, the fiber laminate was pressed against the inner surface of the dry mold, and the fiber laminate was dried while transferring the inner shape of the dry mold. After performing pressure drying for a predetermined time (180 seconds), the pressurized fluid in the elastic core was removed, and the elastic core was contracted and retracted from the drying mold. And the obtained molded object was taken out from the said dry type | mold, it cooled, and the hollow core 1 with a composition shown in Table 1 and the weight of 7g and thickness 1.2mm was obtained with the form shown in FIG.
[0065]
<Casting of castings>
A main mold having a cavity corresponding to the straight tubular casting 10 as shown in FIG. 2 is formed with foundry sand, and the obtained hollow core 1 of φ40 × 100 mm is arranged therein, Was cast without being filled with foundry sand, and a casting was produced at a casting material FC-250 at a casting temperature of 1380 ° C.
[0066]
[Evaluation of moldability of molds, etc.]
The shape of the mold after dry molding was judged visually, and the moldability was evaluated according to the following three steps.
○: The shape of the dry mold is transferred with high dimensional accuracy.
Δ: Although the dimensional accuracy is inferior, the dry mold shape is almost transferred.
X: The shape of the dry mold is hardly transferred.
[0067]
[Evaluation of casting shape retention after casting]
The shape retention of the cast product after casting was judged visually and evaluated in the following three stages.
○: The shape of the mold or the like is transferred with high dimensional accuracy.
Δ: Although the dimensional accuracy is inferior, the shape of a mold or the like is almost transferred.
X: The shape of the mold or the like is hardly transferred.
[0068]
[Evaluation of smoothness of casting surface]
The surface roughness (Ra) of the portion of the obtained casting that was in contact with the mold or the like was measured, and the surface smoothness was evaluated in the following three stages. The surface roughness of the casting was measured by “Surtronic 10” manufactured by Taylor Hobson.
○: 15 μm or less
Δ: More than 15 to less than 50 μm
×: 50 μm or more
[0069]
[Evaluation of mold removability after casting]
The mold removal property after casting was evaluated in the following three stages.
○: Can be easily removed.
Δ: Somewhat difficult to remove
×: difficult to remove
[0070]
[Example 2]
A hollow core having a weight of 9 g and a thickness of 1.2 mm was obtained in the same manner as in Example 1 except that 50 parts by weight of the following obsidian were further added to the material composition shown in Table 1. A casting was then cast in the same manner as in Example 1 except that this hollow core was used and the casting material was FCD-450 (casting temperature 1350 ° C.).
Obsidian: “Nice catch” manufactured by Kinsei Matec, average particle size of 30μm
[0071]
Example 3
A hollow core having a weight of 7 g and a thickness of 1.2 mm was obtained in the same manner as in Example 1 except that the material composition of the mold and the like was changed to the composition shown in Table 1. A casting was then cast in the same manner as in Example 1 except that this hollow core was used and the casting material was AC4A (casting temperature 800 ° C.).
[0072]
Example 4
A hollow core having a weight of 7 g and a thickness of 1.2 mm was obtained in the same manner as in Example 1 except that the material composition such as the mold was changed to the composition shown in Table 1 and the inorganic fibers were changed to the following. Then, using this hollow core, a casting was cast in the same manner as in Example 1.
Inorganic fiber: Pitch-based carbon fiber (“Kureka chop T-106” manufactured by Kureha Chemical Industries, fiber length: 4 mm, shrinkage: 1.5%)
[0073]
Example 5
The material composition such as mold was changed to the composition shown in Table 1, and the thermosetting resin was changed to a commercially available phenol resole resin (residual carbon ratio: 35%). A 2 mm hollow core was obtained. Then, using this hollow core, a casting was cast in the same manner as in Example 1.
[0074]
Example 6
A main die having a cavity corresponding to the straight tubular casting 10 shown in FIG. 2 was formed in the same manner as in Example 1 to obtain a main die having a thickness of 1.2 mm and a weight of 12 g. And the casting was manufactured like Example 1 using this main type | mold.
[0075]
[Comparative Examples 1-4]
A casting was cast in the same manner as in Example 1 except that the material composition of the mold and the like was changed to the composition shown in Table 1.
[0076]
[Comparative Example 5]
A hollow core was obtained in the same manner as in Example 1 except that the material composition such as the mold was changed to the composition shown in Table 1. The obtained hollow core was further impregnated with polyvinyl alcohol to obtain a hollow core having a weight of 7 g and a thickness of 1.2 mm. Using this hollow core, a casting was cast in the same manner as in Example 1.
[0077]
[Comparative Example 6]
A hollow core (weight: about 200 g) having the same shape as in Example 1 was prepared using shell sand made of flattery sand as original sand, and a casting was cast in the same manner as in Example 1.
[0078]
[Table 1]

[0079]
As shown in Table 1, in Examples 1 to 6, the moldability and the like of the mold are also good, the weight is light, and the shape retention and surface smoothness of the mold and the like after casting are equal to or better than those of Comparative Example 6. there were. Further, the removability of the mold after papermaking was also good in each of Examples 1-6. On the other hand, in Comparative Examples 1-3, 5 and the like can be molded, but since the hot strength is inferior, even if the casting is cast using the casting mold or the like, the shape retainability and surface of the casting obtained The smoothness was poor. In particular, in Comparative Example 4, it was difficult to manufacture a mold or the like.
[0080]
【The invention's effect】
According to the present invention, the following effects are exhibited.
1. The casting mold and structure for producing a casting according to the present invention have good moldability, excellent surface smoothness, and can be retained even during casting. For this reason, in the manufacturing method of the casting using this, the surface smoothness of the obtained casting can be improved. In particular, since the post-casting can be greatly reduced without applying a conventional coating agent, it is possible to reduce the number of manufacturing steps for castings.
2. The casting mold and structure for producing a casting of the present invention are excellent in hot strength and shape retention even during casting. For this reason, in the manufacturing method of the casting using this, it is not necessary to harden casting sand with a binder in the case of molding. Therefore, it is not necessary to regenerate the sand by mechanical polishing after casting, and waste can be reduced as compared with the conventional case. In particular, even when applied to a hollow core, it is not always necessary to fill the core with foundry sand.
3. The casting mold and structure for casting production according to the present invention have good removability after casting, and the casting mold and the like can be easily removed as compared with the conventional one.
4). The casting mold and structure for producing a casting according to the present invention are lightweight and therefore easy to handle.
5. In the casting and mold manufacturing method according to the present invention, since the raw material slurry containing organic fibers and inorganic fibers is made and manufactured, a mold in which each component is uniformly dispersed can be obtained. Therefore, the occurrence of cracks and the like due to heat shrinkage is suppressed, high hot strength is obtained, and surface smoothness is excellent. In addition, since a bonding process is not required even in the case of a hollow shape or a complicated three-dimensional shape, the thickness of the final mold or the like is uniform, the molding accuracy and mechanical strength are high, the molding accuracy is high, and the surface is smooth. Castings with excellent properties can be manufactured.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing a casting manufactured using an embodiment in which a casting mold or the like according to the present invention is applied to a hollow core.
FIG. 2 is a perspective view schematically showing a casting manufactured using the hollow core according to the embodiment.
[Explanation of symbols]
1 Hollow core (mold, etc.)
10 Casting

Claims (7)

A casting mold or structure for producing a casting containing organic fiber, inorganic fiber and thermosetting resin. The casting mold or structure according to claim 1, wherein the organic fiber, the inorganic fiber, and the thermosetting resin are paper fiber, carbon fiber, and phenol resin, respectively. The casting mold or structure for manufacturing a casting according to claim 1 or 2, having a thickness of 0.2 to 5 mm. The structure for casting production according to any one of claims 1 to 3, wherein the structure for casting production is a core. The structure for manufacturing a casting according to claim 4, wherein the core is hollow. A casting mold or a structure for producing a casting according to any one of claims 1 to 5, wherein the casting mold comprises a papermaking process using a raw slurry containing at least the organic fiber and the inorganic fiber. Or the manufacturing method of a structure. A casting production method using the casting mold or structure for casting production according to any one of claims 1 to 5.

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