JP4907326B2 - Casting manufacturing structure and casting manufacturing method - Google Patents

Description

  The present invention relates to a structure such as a mold used in manufacturing a casting and a method for manufacturing a casting using the structure.

  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.

  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.

  As a technique for solving such a problem, there is known a technique in which inorganic powder or inorganic fiber is added to cellulose fiber and molded (see Patent Document 1 below). Moreover, the casting_mold | template or structure (refer following patent document 2) containing an organic fiber, an inorganic fiber, an inorganic particle, and a thermosetting resin is known.

  Although these technologies have some effects in terms of weight reduction, workability, and waste material problems, when casting using these molds, gas defects occur on the cast surface and the casting quality deteriorates. There was a problem of inviting. Therefore, a means has been strongly desired to improve these problems.

Japanese Patent Laid-Open No. 9-253792 JP 2005-153003 A

  The subject of this invention is providing the structure for casting manufacture which can improve the gas defect which is casting quality.

  The present invention relates to a structure for producing a casting containing inorganic fibers, inorganic particles, a thermosetting resin, and at least one metal selected from the group consisting of vanadium, titanium, and iron.

  Further, in the present invention, at least one metal selected from the group consisting of vanadium, titanium, and iron is attached to the surface of a casting manufacturing structure containing inorganic fibers, inorganic particles, and a thermosetting resin. The present invention relates to a casting manufacturing structure.

  Moreover, this invention relates to the manufacturing method of the casting which uses the structure for casting manufacture of the said invention.

  In the present specification, the term “structure for casting production” may be included in the category of “mold for casting production”.

  The structure for producing a casting according to the present invention produces a high-quality casting by remarkably improving a casting defect such as a gas defect or a foreign matter biting defect on a casting surface or inside after casting when casting a molten metal. it can.

  Hereinafter, the present invention will be described based on preferred embodiments thereof.

  The structure of the present embodiment is suitable for producing a casting from molten metal.

  The structure of this embodiment contains inorganic fibers, inorganic particles, thermosetting resins, and at least one metal selected from the group consisting of vanadium, titanium, and iron (hereinafter referred to as metal (a)). It is. Or a metal (a) adheres to the surface of the structure for casting manufacture containing an inorganic fiber, an inorganic particle, and a thermosetting resin.

  The blending weight ratio of the inorganic fibers in the structure is preferably 0.1 to 80% by weight, more preferably 1 to 50% by weight, and particularly preferably 1 to 30% by weight. The numerical value of the blending weight ratio may be a numerical value of the content in the structure (the same applies to the following).

  The viewpoint that the weight ratio of the inorganic fiber is 0.1% by weight or more can suppress the decrease in the shape retention of the casting due to the thermal contraction accompanying the decrease in the heat resistance of the structure, and can reduce the amount of gas generated. The weight ratio is preferably 80% by weight or less from the viewpoint of good moldability of the structure and good removability of the structure after casting.

  Moreover, the compounding weight ratio of the inorganic particles is preferably 10 to 95% by weight, more preferably 20 to 90% by weight, and particularly preferably 30 to 85% by weight in the structure.

  The weight ratio of the inorganic particles is preferably 10% by weight or more from the viewpoint that the effect of adding the inorganic particles described later is more easily expressed, and the weight ratio of 95% by weight or less is the moldability of the structure, It is preferable from the viewpoint of improving the shape retention of the casting.

  Moreover, the compounding weight ratio of a thermosetting resin is 3-70 weight% in a structure, Furthermore, 5-50 weight%, Especially 5-30 weight% is preferable.

  It is preferable that the weight ratio of the thermosetting resin is 3% by weight or more from the viewpoint that the smoothness of the casting surface is good and the strength and shape retention of the structure are good. % Or less is preferable from the viewpoint of improving the moldability of the structure and reducing the amount of gas generated to suppress surface defects of the casting.

  Moreover, the compounding weight ratio of the metal (a) is preferably 0.1 to 90% by weight, more preferably 0.5 to 50% by weight, and particularly preferably 1 to 30% by weight in the structure.

  The weight ratio of the metal (a) is preferably 0.1% by weight or more from the viewpoint that gas defects on the casting surface can be reduced, and the weight ratio of 90% by weight or less indicates the structure after casting. It is preferable from the viewpoint that it can be easily removed.

  The inorganic fiber is a component that mainly forms a skeleton in a state before being used for casting in a structure, 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.

  Examples of the inorganic fiber include carbon fiber, glass fiber, artificial mineral fiber such as rock wool, ceramic fiber, and natural mineral fiber. 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.

  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 the structure is made and dehydrated, moldability of the structure, and uniformity. .

  The inorganic fiber has a function of effectively suppressing thermal shrinkage accompanying thermal decomposition of the structure.

  The inorganic particles are components that improve the heat resistance of the structure.

  Examples of the inorganic particles include inorganic particles having a fire resistance of 800 ° C. or higher, such as silica, alumina, mullite, magnesia, zirconia, mica, graphite, obsidian and the like, and 1000 ° C. or higher. Obsidian and mullite powder are preferred from the viewpoint of high viscosity during softening and softening by the heat of the molten metal to form a dense refractory film. Further, graphite is preferable from the viewpoint of excellent moldability of the structure. These inorganic particles may be used alone or in combination of two or more. The inorganic particles preferably have a particle size of 200 μm or less. In particular, inorganic particles having a fire resistance of ± 300 ° C., particularly ± 200 ° C. with respect to the casting temperature of the molten metal to be cast are preferable. Here, the fire resistance of the inorganic particles is measured by a measuring method (JIS R2204) using a Zeger cone.

  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.

  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.

  Examples of the phenolic resin include resol phenol resin, novolac phenol resin, modified phenol resin modified with urea, melamine, epoxy, and the like, preferably resole phenol resin or modified resin thereof.

  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 structure 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.

  When the thermosetting resin is coated on the inorganic fibers or the inorganic particles and further the organic fibers (when blended), or powdered or emulsified and added to the raw material slurry, and after the paper making and dry-molded In order to increase the strength of the structure by impregnating it after making the molded body, drying or curing it, and bonding the molten metal during casting, Carbon that is carbonized by heat to maintain strength, such as carbon film that is carbonized by the heat of molten metal at the time of casting, which can contribute to maintaining the strength of the structure and improving the surface smoothness of the casting If so, any form may be included.

  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.

The metal (a) used in the present invention is at least one metal selected from the group consisting of vanadium, titanium and iron. The metal (a) may be a single metal or an alloy, and is preferably in the form of particles. Various metal particles such as commercially available reagent-level metal particles and metal particles for industrial use can be used as the metal particles. The metal (a) or the alloy containing the metal (a) can be used alone or in combination of two or more. The shape of the metal particles is not particularly limited, and may be spherical or the like, or may be porous. The metal particles preferably have a purity of 30 to 100% by weight. In the case of iron metal particles, iron metal particles treated with iron oxide (Fe ₃ O ₄ ) for the purpose of preventing oxidation by contact with an aqueous solvent [for example, Dowa Kogyo ( Iron powder RKH manufactured by Co., Ltd.] is particularly preferable. As for titanium and vanadium, titanium hydride and vanadium hydride are included (they are thermally decomposed during casting and change into titanium and vanadium, respectively).

  The metal (a) of the present invention is used as a raw material slurry in which these metal particles are added and blended in the composition of a structure such as inorganic fibers, inorganic particles, and thermosetting resin to form an aqueous dispersion medium. Preferably, the structure of the present invention can be produced using such raw material slurry.

  In addition, the casting production structure of the present invention can also be obtained by attaching metal (a) particles to a casting production structure containing inorganic fibers, inorganic particles, and a thermosetting resin by coating or the like. In the case of attaching the metal (a), a binder can be used as a method for improving the adhesion. For example, inorganic binders such as colloidal silica, colloidal alumina, and water glass, and organic binders such as phenol resin, acrylic resin, and vinyl acetate resin can be used. The adhesion amount of the metal (a) is 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, and particularly 0 0.5 to 5 parts by weight is preferred. Note that the structure to which the metal (a) is attached may be either one not containing the metal (a) or one containing the metal (a). Further, even when the structure to be attached does not contain the metal (a), the blending weight ratio of each component in the structure can be within the above range (however, the total is adjusted to be 100% by weight). To do).

  The metal (a) can be attached, in particular, coated by applying a coating solution containing metal particles by brush coating, spray coating, or spray coating. Metal particles with a particle size of 1000 μm or less, more preferably 200 μm or less, particularly 50 μm or less have good dispersibility for use as raw material slurry and coating material, and casting defects due to gas defects and foreign matter biting after casting. Is remarkably improved, which is preferable.

  In the present invention, organic fibers may be further added for the purpose of improving the wet strength when the intermediate formed body after paper making is removed from the paper making mold and the strength of the formed body after drying. The blending weight ratio of the organic fiber is preferably 1 to 70% by weight, more preferably 2 to 50% by weight, and particularly preferably 2 to 30% by weight in the structure. When the ratio is 1% by weight or more, the strength of the molded body is improved, and an excellent moldability is obtained. Further, when the ratio is 70% by weight or less, the amount of gas generated after casting is reduced, surface defects of the casting are hardly generated, heat resistance is improved, and shape retention of the casting is improved.

  The organic fiber is a component that forms a skeleton in the state before being used for casting mainly in the structure and improves the moldability of the structure. Further, when used for casting, it is a component that part or all of it is burned by the heat of the molten metal to form voids in the structure after the casting is manufactured, thereby improving the removability of the structure.

  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.

  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.

  The organic fiber preferably has an average fiber length of 0.3 to 2.0 mm, particularly 0.5 to 1.5 mm, considering the moldability, surface smoothness and impact resistance of the structure.

  In addition to the inorganic fibers, the inorganic particles, the thermosetting resin, and the metal (a), the structure of the present embodiment includes the organic fibers, polyvinyl alcohol, carboxymethyl cellulose (CMC), and polyamidoamine as necessary. Other components such as a paper strength reinforcing material such as epichlorohydrin resin, a polyacrylamide-based flocculant, and a colorant can be added at an appropriate ratio.

  The structure of this embodiment preferably has a surface roughness (Ra) of 20 μm or less, particularly 3 to 15 μm, more preferably 5 to 10 μm. By setting it as such surface roughness, the smoothness of the surface of the casting obtained can be made more excellent. Here, the surface roughness can be measured with a commercially available measuring device as in the examples described later.

  The thickness of the structure according to the present embodiment can be appropriately set according to the portion used, but the thickness at least in 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 molding by filling with casting sand may be insufficient, and the shape function of the structure, especially the core and other structures 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.

  The structure of the present embodiment preferably has a bending strength of 1 MPa or more and more preferably 3 MPa or more in a state before being used for casting.

  When the structure 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 a state before being used for casting from the point of suppressing gas generation during casting as much as possible. (Weight moisture content) is preferably 10% or less, particularly preferably 8% or less.

  The structure of the present embodiment preferably has a specific gravity of 1.5 or less in a state before being used for casting, from the viewpoint of lightness and ease of molding and secondary processing. More preferably, it is 2 or less.

  The structure of the present embodiment can be applied to a main mold having a casting 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 structure 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.

  When the structure of this embodiment is used for the production of castings, as in the past, foundry sand filled around the main mold, iron balls such as shot balls, etc., and filled with hollow cores for backup purposes. Etc. need not necessarily be cured with a binder, so that there is an advantage that the molding sand can be easily regenerated.

Next, the structure manufacturing method of the present invention will be described as a preferred embodiment based on the structure manufacturing method of the above-described embodiment.
In the production method of the present embodiment, a raw material slurry containing the inorganic fiber, the inorganic particles, the thermosetting resin, and the metal (a), more preferably the organic fiber in the predetermined mixing ratio is prepared, and the raw material slurry is prepared. A fiber laminate having a predetermined shape is made by the wet paper making method, and dehydrated and dried to produce a structure.

  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.

  The total ratio of the fibers (including the organic fibers), the inorganic particles, and the metal (a) to the dispersion medium in the raw slurry is 0.1 to 8% by weight, particularly 0.5 to 6% by weight. It is preferable. If the total proportion of the fibers and particles in the raw 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.

  If necessary, additives such as the paper strength reinforcing material, the flocculant, and the preservative can be added to the raw material slurry at an appropriate ratio.

  In the paper making process of the fiber laminate, for example, a cavity having a shape substantially corresponding to the outer shape of the structure 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.

  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.

  Next, the fiber laminate is dry-molded. In this dry molding process, a dry mold having a shape corresponding to the outer shape of the structure to be molded by abutting a pair of split molds and having a cavity opening toward the outside is used. Then, the drying mold is heated to a predetermined temperature, and the dehydrated fiber laminate is loaded into the drying mold. In order to obtain the structure having the surface roughness as described above, the surface roughness (Ra) of the formation surface of the dry-type cavity is preferably 15 μm or less, particularly 10 μm or less, more preferably 3 μm or less.

  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.

  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.

  The heating temperature (mold temperature) of the drying mold is preferably 150 to 300 ° C., particularly 170 to 250 ° C. in consideration of drying time and deterioration of surface properties due to scorching.

  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 to take out the dry-formed structure.

  The obtained structure can be impregnated partially or wholly with a binder and heated to be thermally cured as necessary. Examples of the binder include colloidal silica, ethyl silicate, and water glass.

In the structure thus obtained, inorganic fibers, inorganic particles, thermosetting resin and metal (a), and further, each component of organic fiber is uniformly dispersed, so that cracks caused by heat shrinkage, etc. Generation is suppressed, high hot strength is obtained, and surface smoothness is 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. Furthermore, when a hollow shape or a complicated three-dimensional shape is used, a bonding step is not required, and therefore a seam and a thick portion due to bonding do not exist in the finally obtained structure. 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, it is preferable that the structure is heat-treated in advance at 150 to 300 ° C., particularly 170 to 250 ° C., to advance the curing of the thermosetting resin. By performing such heat treatment, a structure having more excellent shape retention can be obtained. In particular, it is also suitable when there are concerns about the occurrence of gas defects due to the material and shape of the casting.

Next, the manufacturing method of the casting using the structure of the present invention will be described based on the preferred embodiment.
In the manufacturing method of the present embodiment, the predetermined structure obtained as described above is embedded in a predetermined position in the foundry sand for molding. 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. It should be noted that backups such as foundry sand and shot balls need not be cured with a binder, but may be cured as necessary. When the structure is a hollow core, it is not necessary to fill the core with foundry sand, but it can be filled.

  Then, the molten metal is poured from the pouring gate and cast. After the casting is finished, it is cooled to a predetermined temperature, the casting frame is disassembled to remove the foundry sand, and the structure is removed by blasting to expose the foundry. At this time, since the thermosetting resin and further the organic fiber are thermally decomposed, the structure removal process is easy. Thereafter, post-processing such as trimming is performed on the casting as necessary to complete the manufacturing of the casting.

  The casting manufacturing method of the present embodiment uses a structure containing the inorganic fibers, the inorganic particles, the thermosetting resin and the metal (a), and further the organic fibers such as pulp. Casting defects such as gas defects and foreign object biting defects are remarkably improved inside, and high-quality castings can be produced.

  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.

  In the structure of the present invention, as in the above embodiment, in order to form a three-dimensional hollow structure, a formed body is made by a wet paper making method, and the structure is manufactured through dehydration and dry forming steps. It is preferable, however, that the raw material slurry is made into paper to form a sheet-like formed body, and this is rolled up as a paper tube to produce a structure.

  In addition, it is preferable to manufacture so that a structure corresponding to a final shape can be obtained after dry molding, but 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.

  Hereinafter, the present invention will be described more specifically with reference to examples.

[Example 1]
A structure having the material composition shown in Table 1 was produced as follows, and the weight of the obtained structure was measured. In addition, a casting is manufactured using the obtained structure, and the shape retention of the casting (structure retention of the structure), surface smoothness (surface roughness of the casting), and casting defects on the casting surface are as follows: Evaluated. The results are shown in Table 1.

<Preparation of raw material slurry>
After preparing a slurry of about 1% by weight in which the following organic fiber, inorganic fiber, inorganic particle and metal particle were dispersed in water with the formulation shown in Table 1, the following thermosetting resin powder and an appropriate amount of the following flocculant were added to the slurry. Was added to prepare a raw material slurry.
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%)
Inorganic particles: Obsidian (“Nice catch” manufactured by Kinsei Matec Co., Ltd., average particle size 30 μm)
Vanadium particles: manufactured by Wako Pure Chemical Industries, Ltd., vanadium metal powder reagent (particle size -45 μm product)
Thermosetting resin: Spherical phenol resin (Belpearl S-890 manufactured by Air Water Co., Ltd.)
Flocculant: Polyacrylamide flocculant (“A110” manufactured by Mitsui Cytec)

<Paper forming of structure used as hollow core>
The papermaking mold is a pair of split molds having a cavity forming surface (surface roughness (Ra) 0.9 μm) corresponding to φ40 mm × 250 mm, and a net having a predetermined opening is arranged on the cavity forming surface, thereby forming a cavity. What formed many communication holes which connect eyes and the exterior 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. The fiber laminate was then removed from the papermaking mold and transferred to a dry mold heated to 220 ° C. As the drying mold, a pair of split molds having a cavity forming surface corresponding to φ40 mm × 250 mm, in which a large number of communication holes communicating the cavity forming surface with the outside were used. 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 (structure) of the composition, weight, and thickness 1.2mm shown in Table 1 with the form shown in FIG. 1 was obtained. .

<Casting a casting using the hollow core structure>
A main mold having a cavity corresponding to a straight tubular casting 10 as shown in FIG. 2 is formed from foundry sand, and the obtained hollow core 1 having a diameter of 40 mm × 250 mm is arranged therein. Was cast without filling with foundry sand, and a casting was produced at a casting material FCD-700 at a casting temperature of 1400 ° C.

[Evaluation of casting shape retention after casting]
The shape retention of the casting after casting was judged visually and evaluated in the following four stages.
A: The shape of the structure is transferred with very high dimensional accuracy.
○: The shape of the structure is transferred with high dimensional accuracy.
Δ: Although the dimensional accuracy is inferior, the shape of the structure is almost transferred.
X: The shape of the structure is hardly transferred.

[Evaluation of smoothness of casting surface]
The surface roughness (Ra) of the portion of the obtained casting that was in contact with the structure was measured. It shows that it is excellent in smoothness, so that Ra is low. The surface roughness of the casting was measured by “Surtronic 10” manufactured by Taylor Hobson.

[Evaluation of casting defects on the casting surface]
The number of occurrences of casting defects (depressions having a diameter of 0.5 mm or more) such as gas defects and foreign matter biting defects in the portion of the obtained casting that was in contact with the structure (the entire inner surface in FIG. 2) was measured. .

[Examples 2 to 5 and Comparative Example 1]
Except for changing the composition of the structure as shown in Table 1, a hollow core having a thickness of 1.2 mm was obtained in the same manner as in Example 1 with the weight shown in Table 1. Then, using this hollow core, a casting was cast in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. The results are shown in Table 1. The metal particles used in these examples are as follows.
-Titanium particles: manufactured by Toho Titanium Co., Ltd., titanium powder TS-450 (particle size of 45 μm or less: product passing through a sieve having an opening of 45 μm)
・ Titanium hydride particles: manufactured by Toho Titanium Co., Ltd., titanium hydride powder TCH450 (particle size of 45 μm or less: product passing through a sieve having an opening of 45 μm)
Iron particles: manufactured by Dowa Kogyo Co., Ltd., iron powder RKH [iron oxide (Fe ₃ O ₄ ) -treated iron powder (iron purity 82%, Fe ₃ O ₄ 16%), particle size 45 μm: aperture 45 μm (Sheet passing product)

Example 6
Structures having the material compositions shown in Table 2 were produced as follows, and the weight of the obtained structures was measured. Moreover, casting was manufactured using the obtained structure, and evaluation similar to Example 1 was performed. The results are shown in Table 2.

<Paper forming of the structure used as the main mold>
A papermaking body was produced using a papermaking mold provided with a net corresponding to the structure 2 shown in FIG. 3 [(FIG. 3A is a schematic plan view, FIG. 3B is a schematic side view)]. According to the formulation shown in Table 2, preparation, supply, deposition, dehydration, drying, etc. of the slurry used for the production of the papermaking were performed in the same manner as in Example 1. The resulting papermaking had a surface temperature of 180 having the same shape. The mold was transferred to a dry mold at 0 ° C., press-dried at a pressure of 0.6 MPa for 5 minutes, and then removed to obtain the main mold structure 2 having a thickness of 1.2 mm in FIG. The same main mold structure was obtained, and the two structures were bonded to each other by applying an adhesive to the rib surface, and bonded to each other to obtain a main mold structure for casting.

<Casting using the main structure>
In order to obtain a cylindrical casting 20 as shown in FIG. 4, the casting main mold structure formed by the facing-up method in which a gate is provided in a predetermined iron container is installed, and used as a backup filler. Steel shot balls were filled, and a casting was produced at a casting material FCD-700 and a casting temperature of 1400 ° C.

[Example 7 and Comparative Example 2]
A casting was cast in the same manner as in Example 6 except that the material composition of the structure was changed to the composition shown in Table 2. Table 2 shows the results of the same evaluation as in Example 6.

Example 8
A 50% by weight aqueous dispersion of titanium particles (used in Example 2) was applied to the surface of the structure used in Comparative Example 2 with a brush, and the titanium particles coated were dried at 180 ° C. for 2 hours. A structure coated with titanium metal particles was obtained. A casting was cast in the same manner as in Comparative Example 2 except that the structure was used. In addition, the coating amount of the titanium particles is 3 parts by weight with respect to 100 parts by weight of the structure (before coating).
Example 9
The surface of the structure used in Comparative Example 2 was coated with a 50% by weight aqueous dispersion of iron particles (used in Example 4) with a brush, and the coated iron particles were dried at 180 ° C. for 2 hours, A structure coated with iron particles was obtained. A casting was cast in the same manner as in Comparative Example 2 except that the structure was used. In addition, the coating amount of iron particles is 3 parts by weight with respect to 100 parts by weight of the structure (before coating).

  In Table 2, inorganic fibers, inorganic particles, thermosetting resin, metal particles, and organic fibers are the same as those in Examples 1 to 5 and Comparative Example 1.

  As shown in Tables 1 and 2, Examples 1 to 9 are lightweight, have good shape retention after casting and good surface smoothness of the casting inner surface, have few casting defects on the casting surface, and have gas defects. It can be seen that the prevention effect is high. On the other hand, in Comparative Examples 1 and 2 in which no metal particles are added, it can be seen that there are many casting defects on the casting surface, and gas defects are not sufficiently suppressed.

It is a perspective view which shows typically the hollow core which is an example of the structure for casting manufacture of this invention. It is a perspective view which shows typically the casting manufactured using the hollow core of FIG. It is a figure which shows typically the structure for main molds which is an example of the structure for casting manufacture of this invention. It is a perspective view which shows typically the casting manufactured using the structure of FIG.

Explanation of symbols

1 Hollow core (structure)
10 Casting 2 Main mold structure 20 Casting

Claims (7)

A casting manufacturing structure containing inorganic fibers, inorganic particles, a thermosetting resin, and at least one metal selected from the group consisting of 0.1 to 30% by weight of vanadium, titanium, and iron in the structure.   The casting according to claim 1, wherein at least one metal selected from the group consisting of vanadium, titanium, and iron is attached to the surface of a structure for manufacturing a casting containing inorganic fibers, inorganic particles, and a thermosetting resin. Manufacturing structure.   The structure for manufacturing a casting according to claim 1 or 2, wherein the thickness is 0.2 to 5 mm. In the structure, the inorganic fibers 0.1 to 80 wt%, the inorganic particles 10 to 95 wt%, producing castings according to any one of claims 1 to 3 containing a thermosetting resin 3 to 70 wt% Structure. Furthermore , the structure for casting manufacture of any one of Claims 1-4 which contains organic fiber 1 to 70weight% in a structure.   The structure for casting production according to any one of claims 1 to 5, wherein the inorganic particles are inorganic particles selected from silica, alumina, mullite, magnesia, zirconia, mica, graphite, and obsidian.   A casting manufacturing method using the casting manufacturing structure according to claim 1.

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