JP5419429B2 - Molded object for mold, method for producing molded object for mold, and method for producing casting - Google Patents

Description

  The present invention relates to a molded article for a mold containing inorganic particles and a method for producing the same, and further relates to a method for producing a casting using the molded article for a mold as a casting mold.

  When casting a hollow casting in a general casting manufacturing method, a core is formed with foundry sand, the core is set in a main mold, molten metal is cast, and the mold is opened after cooling. After demolding the casting, the core is disintegrated and removed to obtain the desired casting.

  By the way, the core is shaped by curing casting sand with binder added to normal shell mold sand (coating sand of novolak phenol resin and hexamine curing agent), so decomposition of amine, formaldehyde, etc. during casting There was a problem of generating gas. Moreover, since it was fragile, when it set to the main type | mold, or when kelen was mounted | worn, the point which was easy to break at the time of pouring was a subject. Furthermore, when sand is reused, a regeneration process is required. However, there is a problem that waste such as dust is generated during the regeneration process.

  In the technique described in Patent Document 1, a molded body for casting used for casting is composed of a molded body containing organic fibers, inorganic fibers, and a thermosetting resin. The mold for molding by this technique is thinner and lighter than the conventional mold for mold using casting sand, and is excellent in workability. Further, there is no problem that the above-mentioned waste is generated. However, since this molded article for mold is produced by papermaking, a molded article for mold that can be produced by a simpler method has been desired. Further, in the manufacture by papermaking, it has been difficult to form a complicated shape in which the thickness of the molding for the mold changes greatly.

Patent Document 2 uses a kneaded material mainly composed of a hydraulic substance, ultrafine powder and heat-resistant aggregate, has a compression strength after curing of 50 to 400 kgf / cm ² , and a use temperature of 250 to 1100 ° C. A high temperature mold is described. Although a polyacrylate is described as a water reducing agent and manufacturing of a mold becomes easy, the problem of gas generation at a high temperature is not recognized.

  On the other hand, Patent Document 3 proposes a technique for injection-molding a raw material containing organic fibers and a binder to form a molded body, but molding a complicated shape that greatly changes the thickness of the molded body. However, since the main component of the material is an organic material, a molded body made using this technique generates a large amount of decomposition gas when the organic material burns, so it can be used as a mold. could not. Furthermore, the dispersion medium such as water contained in the raw material often separates during injection molding.

JP 2004-181472 A Japanese Patent Laid-Open No. 2-89538 JP-A-11-280000

  An object of the present invention is to provide a molded article for a mold that can suppress generation of a decomposition gas during use and has excellent room temperature strength, hot strength, and handleability after use, and a method for producing the same. .

  The present invention contains an inorganic fiber, a thermosetting resin, and a carboxyvinyl polymer having a 0.1% by mass aqueous solution viscosity at 25 ° C. of 100 to 10,000 mPa · s (hereinafter sometimes simply referred to as carboxyvinyl polymer). The present invention relates to a molded article for a mold.

  In addition, the present invention provides a molding raw material obtained by dispersing inorganic particles, inorganic fibers, a thermosetting resin, and a carboxyvinyl polymer having a 0.1 mass% aqueous solution viscosity at 25 ° C. of 100 to 10,000 mPa · s in a dispersion medium. The present invention relates to a method for producing a molded article for a mold, which includes a step of filling a mold and heating the mold to cure the thermosetting resin.

  Moreover, this invention relates to the manufacturing method of a casting which has the process of casting a molten metal in the molded object for molds of the said invention.

  According to the present invention, generation of decomposition gas during use is suppressed to a low level, and a molded article for molds having excellent room temperature strength, hot strength, and handleability after use, a method for producing the same, and the molded article for molds as a mold. A method for producing the casting used is provided.

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

  First, the molded body of the present invention will be described based on an embodiment in which it is applied to a core (mold or the like) for casting production.

  The molded body of this embodiment contains inorganic particles as the main component and contains inorganic fibers, a thermosetting resin, and the specific carboxyvinyl polymer. In the present specification, the phrase “mainly composed of inorganic particles” means that the number of inorganic particles is the largest in all components contained in the molded body.

  In the molded body of the present embodiment, the blending ratio (mass ratio) of each component with respect to the total mass of inorganic particles, inorganic fibers, thermosetting resin, and carboxyvinyl polymer (solid content) is inorganic particles / inorganic fibers / Thermosetting resin / carboxyvinyl polymer = 40 to 90/1 to 20/1 to 30 / 0.5 to 10 (mass ratio) is preferable, and 50 to 85/2 to 16/2 to 20/1 to 5 (mass ratio) Ratio) is more preferable. (However, the sum of the mass ratios is 100.)

  When the blending of the inorganic particles is within the above range, the shape retainability of the molded body used as a mold at the time of casting (hereinafter simply referred to as shape retainability), the surface property of the cast molded product becomes good, and after casting The mold releasability from the casting mold is also good. When the blending ratio of the inorganic fibers is within the above range, the moldability of the mold body and the shape retention during casting are good. When the blending ratio of the thermosetting resin is within the above range, the moldability of the molding for mold, the shape retention after casting, and the surface smoothness of the casting are good. When the compounding ratio of the carboxyvinyl polymer is within the above range, when the molding material (inorganic particles, inorganic fibers, thermosetting resin, carboxyvinyl polymer, etc.) is filled in the molding die, the molding material and the dispersion medium described later are used. The fluidity of the slurry-like composition becomes good without separation.

  Examples of the inorganic particles include graphite such as plate-like graphite (scale-like graphite), earth-like graphite, artificial graphite powder (chips generated when processing electrode carbon), obsidian, mica, mullite, silica, magnesia, talc. Etc. One or more inorganic particles can be selected and used. From the viewpoints of moldability and cost, it is preferable to use graphite, plate-like graphite (scale-like graphite), and artificial graphite powder.

  The inorganic fiber mainly forms a skeleton of a molded body, and maintains its shape without being burned by the heat of molten metal during casting, for example. Examples of the inorganic fibers include artificial mineral fibers such as carbon fibers and rock wool, ceramic fibers, and natural mineral fibers. One or two or more inorganic fibers can be selected and used. 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 further, PAN-based carbon. Fiber is preferred.

  The inorganic fibers preferably have an average fiber length of 0.5 to 15 mm, more preferably 1 to 8 mm, from the viewpoint of moldability and uniformity of a mold or the like.

  The thermosetting resin is necessary for maintaining the normal temperature strength and hot strength of the molded body, improving the surface properties of the molded body, and improving the surface roughness of the casting when the molded body is used as a mold. Is an essential ingredient. Examples of the thermosetting resin include a phenol resin, an epoxy resin, and a furan resin. Among these, furthermore, there is little generation of combustible gas, there is a combustion suppression effect, the residual carbon ratio after pyrolysis (carbonization) is as high as 25% or more, and a carbonized film is formed when the molded body is used as a mold. It is preferable to use a phenol resin from the viewpoint that a good casting surface can be obtained. As the phenol resin, a novolak phenol resin that requires a curing agent or a resol type phenol resin that does not require a curing agent is used. One or two or more thermosetting resins can be selected and used.

  The carboxyvinyl polymer used in the present invention has a 0.1 mass% aqueous solution viscosity at 25 ° C. of 100 mPa · s or more, preferably 200 mPa · s or more, more preferably 250 mPa, from the viewpoint of improving the transferability of the molded product. -It is more than s. The viscosity is 10,000 mPa · s or less, preferably 9,000 mPa · s or less, and more preferably 8,000 mPa · s or less. This viscosity is the rotor No. 3 and measured at a rotational speed of 60 rpm, specifically, measured by the following method [hereinafter referred to as viscosity (I)]. Further, in the same manner as this viscosity (I), except that the viscosity of a 0.1% by mass aqueous solution at 25 ° C. (hereinafter referred to as viscosity (II)) measured at a rotor rotational speed of 6 rpm is 50 mPa · s or more, It is preferably 80 mPa · s or more, more preferably 100 mPa · s or more, more preferably 5,000 mPa · s or less, further 3,000 mPa · s or less, and even more preferably 2,000 mPa · s or less. The ratio of viscosity (I) to viscosity (II), which is an index of thixotropy, is 1.50 to 5.00 in terms of viscosity (I) / viscosity (II), further 1.75 to 4.75, and more It is preferably 2.00 to 4.50.

<Measurement method of viscosity (I) and viscosity (II)>
A 1 liter beaker equipped with a stirrer is prepared, 0.80 g of carboxyvinyl polymer is accurately weighed and dispersed in 900 g of tap water (soft water). Subsequently, 0.80 g of 25% by mass aqueous sodium hydroxide solution is accurately weighed and added. Thereafter, stirring is continued for 2 hours at room temperature until the dispersion is completely dissolved and becomes a homogeneous solution. After confirming that the aqueous carboxyvinyl polymer solution is uniform, the pH is measured with a pH meter. The pH at this point may be 6-7. Subsequently, after dropping several drops of 25% by mass aqueous sodium hydroxide solution until the pH reaches 7.5, tap water (soft water) is added to the solution so that the carboxyvinyl polymer aqueous solution becomes 1000.0 g, and the mixture is stirred with a stirrer so as to be uniform. A 0.1% by mass carboxyvinyl polymer aqueous solution is obtained.

After 24 hours, about 250 cc of the 0.1 wt% carboxyvinyl polymer aqueous solution was transferred to a tall beaker having an inner diameter of 43 mm and a height of 200 mm, and the 0.1 wt% carboxyvinyl polymer aqueous solution was placed in a constant temperature water bath at 25 ° C. Soak. It confirms that the said carboxy vinyl polymer aqueous solution became 25 degreeC, and measures a solution viscosity.
Measuring device: B type viscometer (manufactured by Toki Sangyo Co., Ltd.)
Rotor: No. 3
Rotation speed: 60rpm or 6rpm

  As an example, the carbopol 940 has a viscosity (I) of 2380 mPa · s, a viscosity (II) of 536 mPa · s, a viscosity (I) / viscosity (II) of 4.44, and the carbopol ULTREZ 21 has a viscosity ( I) is 300 mPa · s, viscosity (II) is 122 mPa · s, viscosity (I) / viscosity (II) is 2.46, and Carbopol ETD2020 has a viscosity (I) of 7140 mPa · s and viscosity (II). Is 1710 mPa · s, and viscosity (I) / viscosity (II) is 4.18. Polysodium acrylate having a weight average molecular weight of 2000 known as a water reducing agent has a viscosity (I) of 40 mPa · s, a viscosity (II) of 30 mPa · s, and a viscosity (I) / viscosity (II) of 1. 33.

  The carboxyvinyl polymer used in the present invention has a 0.1 mass% aqueous solution viscosity at 25 ° C. of 100 to 10,000 mPa · s. Specific examples include acrylic acid monomers such as acrylic acid, methacrylic acid, homopolymers of alkyl methacrylates (10 to 30 carbon atoms) or copolymers containing these as constituent monomers. Those crosslinked with a crosslinking agent selected from stilallyl ether, sucrose allyl ether and propylene allyl ether are preferred. As a general synthesis method, when a monomer containing the acrylic acid monomers (partially neutralized with an alkali in some cases) is included in the constituent monomer, the radical initiator [potassium persulfate ( KPS), azobisisobutyronitrile (AIBN), benzoyl peroxide, and the like] through a radical polymerization reaction. Further, the molecular weight of the carboxyvinyl polymer is preferably from 300,000 to 5,000,000 in terms of weight average molecular weight (polystyrene conversion) from the viewpoint of the state of the molding raw material (such as dough). Specific examples of the carboxyvinyl polymer include carbopol 940, carbopol 980, and carbopol 981. Among them, as specific examples of acrylic acid / alkyl methacrylate (carbon number 10 to 30) ester copolymer, carbopol PEMULEN TR-1, carbopol PEMULEN TR-2, carbopol ULTREZ 21, carbopol ULTREZ 10, carbopol. 1342, Carbopol 1382, Carbopol ETD2020 (all manufactured by Lubrizol, USA) and the like. In the step of synthesizing these carboxyvinyl polymers, a part or all of them may be neutralized to take a salt form. Basic substances used in the step of synthesizing carboxyvinyl polymer (basic neutralizers) such as alkali metal salts such as sodium hydroxide, potassium hydroxide and lithium hydroxide, ammonium hydroxide, organic amines and basic amino acids Can be used. In the present invention, the carboxyvinyl polymer is preferably a polymer containing an alkyl methacrylate (carbon number 10 to 30) ester as a constituent monomer, and in particular, a copolymer of acrylic acid and an alkyl methacrylate (carbon number 10 to 30) ester. A polymer is preferable, and further, a carboxyvinyl polymer having a weight average molecular weight of 300,000 to 5,000,000, which is crosslinked with a crosslinking agent is preferable.

  The carboxyvinyl polymer may be at least partially neutralized in the step of preparing the molding raw material (for example, dough-like product) used in the present invention. Specifically, as the base, the same basic substances as described above can be used. Moreover, you may mix | blend a suitable basic substance in the dispersion mixture for shaping | molding raw material preparation.

  In the present invention, the forming raw material is preferably in the form of a slurry, and more preferably in the form of a dough. Further, from the viewpoint of moldability of the mold, the pH of the molding raw material (in particular, the molding raw material containing water as a dispersion medium) at 25 ° C. is preferably 5 to 12, more preferably 6 to 10, and more preferably 6.5 to 9. . This pH is usually the pH of the aqueous phase portion of the forming raw material. If it is difficult to measure the pH as it is like a dough-like material, it is pure with respect to 10 g of the measurement object such as the dough-like material. The pH of the diluted mixture (slurry etc.) diluted at a mass ratio of 30 g of water shall be measured.

  In the present invention, by using the specific carboxyvinyl polymer, an appropriate thickening can be expressed, so when using polyacrylic acid as a conventional polyvinyl alcohol, polyacrylamide flocculant or water reducing agent Is more excellent in fluidity and moldability when producing molding raw materials such as dough-like products, and as a result, it is remarkably reduced in decomposition gas, room temperature strength, hot strength, and handling properties after use of the mold. It has been found that an excellent molded article for a mold can be obtained. In addition, the present inventors have found that the carboxyvinyl polymer used in the present invention can obtain an excellent effect at a low addition amount, and can suppress the pyrolysis gas at the time of casting to a minimum, thereby improving the quality of the cast casting. In addition, normally, the weight average molecular weight of the polyacrylic acid used for a water reducing agent is about 300-3000, and a viscosity (I) will be about 40 mPa * s as above-mentioned.

  The molded body of the present embodiment preferably includes thermally expandable particles. The heat-expandable particles are preferably microcapsules in which an expansion agent that expands by vaporization is encapsulated in the shell wall of a thermoplastic resin. When the microcapsule is heated at 80 to 200 ° C., the diameter preferably expands to 3 to 5 times, the volume preferably expands to 50 to 100 times, and the average particle diameter before expansion is preferably 5 to 80 μm, more preferably Particles of 20-50 μm are preferred. When the expansion of the thermally expandable particles is within such a range, the effect of addition can be sufficiently obtained while suppressing the adverse effect on the molding accuracy due to the expansion. The thermally expandable particles preferably have an average diameter before expansion of 5 to 80 μm, more preferably 20 to 50 μm.

  Examples of the thermoplastic resin constituting the shell wall of the microcapsule include polystyrene, polyethylene, polypropylene, polyacrylonitrile, acrylonitrile-vinylidene chloride copolymer, ethylene-vinyl acetate copolymer, or combinations thereof. Examples of the expanding agent contained in the shell wall include low-boiling organic solvents such as propane, butane, pentane, isobutane, and petroleum ether.

  The thermally expandable particles include 0.5 to 10% (mass%) with respect to the total mass of the inorganic particles, the inorganic fibers, the organic fibers, the thermosetting resin, and the thermally expandable particles. It is more preferable that it contains 1 to 5% (mass%). When the heat-expandable particles are contained in such a range, the molding material is filled in the details of the mold by the expansion, and the shape of the mold can be fully transferred, and the effect of addition can be sufficiently obtained. Further, in the case of the above range, since a large amount of thermally expandable particles is not included, overexpansion can be prevented, and an extra cooling time is not required, so that high productivity can be maintained.

  In addition to the components described above, other components such as a colorant, a release agent, and colloidal silica can be added to the molded body of the present embodiment at an appropriate ratio. Moreover, the molded object of this embodiment can contain a tree fiber in the range which does not exert a bad influence on the effect. Examples of the organic fiber include paper fiber (pulp fiber), fibrillated synthetic fiber, and regenerated fiber (for example, rayon fiber). One or two or more organic fibers can be selected and used. Paper fiber is preferable from the viewpoints of moldability, strength after drying, and cost.

  When the molded body of this embodiment is produced from a raw material containing water, the mass moisture content before use of the molded body (before being used for casting) is preferably 5% or less, and more preferably 2% or less. . The lower the moisture content, the lower the amount of gas generated due to thermal decomposition (carbonization) of the thermosetting resin during casting.

FIG. 1 is a schematic view of an embodiment in which the molded body of the present invention is applied to a hollow core having a hollow inside.
The front end 101 of the molded body 10 is closed and the rear end 102 is open. Moreover, the molded object 10 has a part where an outer diameter becomes thick, and in this embodiment, the outer diameter of the rear-end part 102 is formed thicker than another part. The molded body of the present invention is suitable for a molded body having such a hollow and slender bar shape.

  Next, the manufacturing method of the molded object of this invention is demonstrated as a preferable embodiment based on the manufacturing method of the molded object 10 of the said embodiment.

  FIG. 2 is a schematic diagram of an embodiment of a manufacturing apparatus for carrying out the method for manufacturing a molded body according to the embodiment. In these drawings, reference numeral 1 denotes a manufacturing apparatus.

  As shown in FIG. 2, the manufacturing apparatus 1 includes a molding die 2, a core material 3 inserted into the molding die 2, a gate opening / closing means 4 of the molding die 2, and supply of raw materials into the molding die 2. Means 5 are provided.

  The mold 2 is composed of a pair of split molds 2A and 2B. By combining these split molds, the mold 2 has a cavity 20 formed therein, and a gate hole 21 leading to the cavity and an entrance / exit 22 of the core material 3 are formed. A cavity forming surface formed by the inner surface of each split mold corresponds to the outer shape of the molded body 10. In the split mold 2 </ b> B, a raw material inlet 23 leading to the gate hole 21 is formed. The split mold is made of a metal such as an aluminum alloy or stainless steel. The mold 2 is attached to a platen of mold clamping means (not shown), and is opened and closed in the vertical direction. Each split mold is heated to a predetermined temperature by a heating means (not shown).

  The core material 3 has a rod-like shape in which a tapered portion 30 is provided at the tip portion. The outer surface of the core material 3 corresponds to the inner surface shape of the hollow portion of the molded body 10. The core material 3 is driven back and forth by a driving means (not shown), and is put in and out through the entrance / exit 22 of the mold 2.

  The gate opening / closing means 4 includes a gate pin 40 that slides in the gate hole 21. The gate pin 40 is driven back and forth by driving means (not shown), and the tip portion slides in the gate hole 21 of the mold 2.

  The raw material supply means 5 includes a so-called fluid pressure cylinder / piston unit. The raw material supply means 5 includes a cylinder 50 in which the raw material is stored, a piston 51 that slides in the cylinder 50, and a nozzle 52 that discharges the raw material pressed by the piston 51. The raw material supply means is configured such that when the nozzle 52 is inserted into the raw material inlet 23 and a fluid such as pressurized air is supplied into the cylinder 50, the piston 51 rises and the raw material 100 in the cylinder 50 is supplied. Is supplied to the gate hole 21 through the nozzle 52.

  The manufacturing apparatus 1 includes control means (not shown) including a sequencer that operates the molding die 2, the core material 3, the gate opening / closing means 4, and the raw material supply means 5 in accordance with a procedure described later.

  Next, the manufacturing method of the molded object of this invention is demonstrated, referring FIGS. 2-6 based on embodiment by the manufacturing method of the said molded object 10 using the said manufacturing apparatus 1. FIG.

  In the method for producing a molded body according to this embodiment, the inorganic particles, the inorganic fibers, the thermosetting resin, and the carboxyvinyl polymer agent are mixed in advance by a dry method. When the thermally expandable particles are included, they are included at the time of this dry mixing. And these mixtures are disperse | distributed to a dispersion medium, and it knead | mixes, for example with a kneader, Preferably a raw material is prepared in dough shape.

  Examples of the dispersion medium include water, a solvent such as ethanol and methanol, and an aqueous dispersion medium such as a mixed system thereof. Water is preferable from the viewpoint of stability of the quality of the molded product, cost, ease of handling, and the like.

  Here, preparation of the raw material in a dough shape means that a solid component (solid dispersoid) such as inorganic particles and inorganic fibers and a dispersion medium are kneaded and solid, such as inorganic particles and inorganic fibers, while having fluidity. It means that the component (solid dispersoid) and the dispersion medium are prepared so that they are not easily separated. It is preferable to use such a dough-shaped forming raw material from the viewpoint of moldability. Specifically, the filling property into a mold (such as a mold) is improved, and leakage of a liquid material from a slit of the mold or the like. Therefore, molding defects such as generation of burrs can be reduced.

  Next, as shown in FIG. 2, the mold 2 is clamped and the core material 3 and the gate pin 40 are set. The temperature of the mold at this time is preferably 120 to 250 ° C. in consideration of the evaporation of the dispersion medium, the curing rate of the thermosetting resin, the expansion rate of the thermally expandable particles, the burning of the material, and the like. Then, as shown in FIG. 3, the raw material 100 is filled into the mold 2 while being pressurized from the inlet 23 by raising the piston 51 of the raw material supply means 5. When air is used for the pressurized fluid of the raw material supply means 5, the air pressure is preferably 0.5 to 3 MPa.

  Next, as shown in FIG. 4, the gate pin 40 is advanced by the driving means, and the cavity 20 is sealed.

  After the heating for a predetermined time, the core material 3 is once retracted by the driving means during the molding in order to release the steam from the inside of the molded body 10, and the tapered portion 30 is applied to the entrance / exit 22 as shown in FIG. The drawing of the core material 3 is stopped. Then, steam is vented to suppress damage to the molded body due to rapid deaeration.

  After performing necessary steam removal, the molded body is dried by continuing heating for a predetermined time. And as shown in FIG. 6, the gate pin 40 is retracted, the shaping | molding die 2 is opened, and the molded object 10 is taken out. The molded body 10 is post-cooled and subjected to post-processing such as trimming, chemical application, and reheating as necessary after completion of cooling.

  The molded body of this embodiment contains inorganic particles, thermosetting resin, and a carboxyvinyl polymer composed of a water-soluble polymer compound as a main component, is lightweight, has high normal temperature strength, and kelen. Excellent handling when used as a core. Moreover, since there is little generation | occurrence | production of the gas accompanying thermal decomposition at the time of use, the bad influence on an environment can be restrained low. In addition, since the dimensional accuracy is high and the hot strength is high, a highly accurate casting can be stably manufactured. When the thermally expansible particles are included, since it is a molded body with high molding accuracy over the details, a casting with higher accuracy can be manufactured. In addition, since the interior is hollow, it is lighter and it is possible to discharge cracked gas generated during casting from the hollow portion to the outside, and after use, it can be easily made fine by blasting or the like. It is also excellent in handling after casting.

  The manufacturing method of the molded object of this embodiment can manufacture suitably the molded object which has the said effect. Furthermore, since the core material 3 is once pulled out during the molding and is extracted, and then dried, the molded body can be manufactured at a high speed while suppressing damage to the molded body due to vapor explosion or the like.

  Next, a method for manufacturing a casting according to the present invention will be described based on an embodiment in which the core made of the molded body is used as a mold or the like and applied to a method for manufacturing a hollow rod-shaped casting.

  In the casting manufacturing method of this embodiment, as shown in FIG. 7 (plan view), the kelens 12 are arranged at predetermined intervals in the cavity 111 of the lower mold 11A of the main mold 11, and the molded bodies are formed by these kerens 12. 10 is supported. Then, an upper mold (not shown) is set on the lower mold 11 </ b> A, and molten metal is cast from the inlet 13. The main mold 11 is provided with a gas vent 14 so as to communicate with the hollow portion of the molded body 10, and a decomposition gas of the molded body generated during casting is discharged from here.

  As the main mold 11 and the kelen 12, known ones conventionally used for casting can be used in accordance with the material and form of the casting to be cast and the form of the molded body 10. Moreover, the usual metal conventionally used can be used for a molten metal without a restriction | limiting.

  After the cast molten metal is sufficiently cooled, the main mold is removed and a desired casting is taken out. Then, the remaining part of the molded body 10 remaining inside is removed by blasting or the like, and trimming or the like is performed as necessary to complete the casting.

  According to the casting manufacturing method using the molded body 10 of the present embodiment, a rod-shaped casting with a hollow interior can be accurately and suitably manufactured.

  The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

  In addition to the core used for casting as in the above-described embodiment, the molded body of the present invention includes a mold (main mold), a runner, a hot water stop, a receiving port, a pouring gate, a pouring gate, a cough, venting, and frying. It is suitable for the use of a structure such as a hot spring and other incidental structures. Further, it can be applied to uses other than the casting field requiring heat resistance, and the molding accuracy can be high over the details of the shape according to the use.

  In addition, as long as there is little quantity of the decomposition gas generate | occur | produced at the time of casting and it does not affect implementation of this invention, the organic fiber may be included in the molded object of this invention.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not restrict | limited to a present Example at all.

  As in Examples 1 to 3 and Comparative Examples 1 and 2 below, molded articles having the following dimensions and shapes were prepared from the raw materials having the following compositions, and the room temperature strength, hot strength, and disintegration after use were as follows. Evaluated. The results are shown in Table 1. In addition, a hollow rod-shaped casting was produced using the obtained molded body as a core (such as a mold). About the obtained casting, the shape transcription | transfer property of the hollow part, etc. were evaluated as follows. The results are shown in Table 2.

[Example 1]
(1) Preparation of a dough-like material as a raw material of a molded body As a kneading machine, “Shintaro Awatori” manufactured by Shinkey Co., Ltd. is used, and inorganic particles, inorganic fibers, thermosetting resins and carboxyvinyl polymers are After mixing according to the blending ratio (mass ratio) to 100 parts by mass, 150 parts by mass of water as a dispersion medium was added to this mixture and kneaded for 5 minutes to obtain a moisture content of 60% by mass (solid content 40% by mass). 250 g of a dough-like product was prepared. During kneading, the temperature of the dough increased from 25 ° C to 60 ° C.

<Composition ingredients of raw materials>
Inorganic particles: Earth-like graphite Inorganic fibers: PAN carbon fiber (trade name “Pyrofil” manufactured by Mitsubishi Rayon Co., Ltd.), fiber length: 3 mm, shrinkage: 0.1%)
Thermosetting resin: Phenolic resin ("Bellpearl S-890" manufactured by Air Water Co., Ltd.)
Carboxyvinyl polymer: Carbopol S-940 [manufactured by Lubrizol, USA, viscosity (I) 2380 mPa · s, viscosity (II) 536 mPa · s, viscosity (I) / viscosity (II) 4.44]
Component mass ratio (%): inorganic particles / inorganic fibers / thermosetting resin / carboxyvinyl polymer = 70/8/20/2
Dispersion medium: water

(2) Adjustment of pH of dough-like substance A 25% aqueous solution of caustic soda was added as a pH adjuster so that the pH of the dough-like substance at 7C (pH defined above) was 7-8. At that time, 2 parts by mass of 25% aqueous sodium hydroxide solution was added to 2 parts by mass of Carbopol S-940. In addition, the slurry which diluted 10 g of samples (dough-like material) with 30 g of pure water was used for pH measurement.

(3) Production of molded body by injection molding The dough-like product was injection molded under the following conditions to obtain a molded body.
Air pressure of raw material supply means: 1 MPa
Mold temperature: 180 ° C
Dimensional shape of molded body: hollow rod-shaped product with outer diameter 14mm, length 300mm, hollow part diameter 8mm

(4) Casting of cast body The obtained molded body was used as a core, and molten metal having the following components was injected to cast a casting having the following form.
Molten metal: Cast iron JIS FC100 equivalent, molten metal temperature 1400 ° C
Form of casting: hollow rod-shaped product having an outer diameter of 30 mm, a length of 250 mm, and a hollow part diameter of 14 mm.

[Example 2]
A molded body was produced in the same manner as in Example 1 except that the raw material of Example 1 contained the following thermally expandable particles at the following blending ratio.
Thermally expandable particles: Thermally expandable microcapsules (Matsumoto Yushi Seiyaku Co., Ltd., trade name "Matsumoto Microsphere F-793D"
Component mass ratio (%): inorganic particles / inorganic fibers / thermosetting resin / carboxyvinyl polymer / thermally expandable particles = 68/8/20/2/2

Example 3
Instead of Carbopol S-940 (manufactured by Lubrizol, USA) used in Example 2, acrylic acid / alkyl methacrylate (carbon number 10-30) ester copolymer [Carbopol ULTREZ 21, Lubrizol, USA) as a carboxyvinyl polymer Example 2 except that the viscosity ratio (I) was 300 mPa · s, viscosity (II) 122 mPa · s, viscosity (I) / viscosity (II) 2.46], and the blending ratio of the raw materials was as follows. A molded body was produced in the same manner as described above.
Component mass ratio (%): inorganic particles / inorganic fibers / thermosetting resin / carboxyvinyl polymer / thermally expandable particles = 68/8/20/2/2

[Comparative Example 1]
Instead of the carboxyvinyl polymer used in Example 1, polyvinyl alcohol [manufactured by Nippon Synthetic Chemical Co., Ltd., Gohsenol NM-14, viscosity (I) (no pH adjustment) 1.5 mPa · s, viscosity (II) (pH No adjustment) 1.3 mPa · s, Viscosity (I) / Viscosity (II) 1.154], and a molding was produced in the same manner as in Example 1 except that the mixing ratio of the raw materials was as follows. .
Component mass blending ratio (%): inorganic particles / inorganic fibers / thermosetting resin / polyvinyl alcohol = 70/8/20/2

[Comparative Example 2]
Instead of the carboxyvinyl polymer used in Example 1, a polyacrylamide-based flocculant (A110 manufactured by Mitsui Cytec Co., Ltd.) was used, and the mixing ratio of the raw materials was as described below. A molded body was produced.
Component mass blending ratio (%): inorganic particles / inorganic fibers / thermosetting resin / polyacrylamide type flocculant = 70/8/20/2

[Evaluation of room temperature strength of compacts]
The room temperature strength of the molded body was evaluated according to the following criteria.
A: No breakage or chipping occurs at the time of placement on the mold or when keren is attached.
B: Folding or chipping occurs during placement in the mold or when keren is mounted, or a defective part of the molded body is dropped into the mold.

[Evaluation of hot strength of compacts]
By visually judging the shape and surface properties of the hollow portion formed in the casting, the hot strength of the molded body was evaluated according to the following criteria.
A: Neither bending due to molten metal pressure, insertion, or poor seizure is observed in the hollow portion.
B: Any of bending due to molten metal pressure, insertion, or poor seizure is observed in the hollow portion.

[Evaluation of disintegration of molded product after use as mold]
By subjecting the casting to sand blasting and visually determining whether or not the molded product remained in the hollow portion, the disintegration property of the molded product after use was evaluated according to the following criteria.
A: A molded product residue is not observed on the inner surface of the hollow part.
B: A residue of the molded product is observed on the inner surface of the hollow part.

<Result>
As shown in Table 1, the molded product obtained in the present invention had sufficient performance as a casting core.

[Evaluation of shape transferability of hollow parts of castings]
The hollow bar-shaped casting was divided and cut in the axial direction and visually judged to evaluate the shape transferability of the hollow portion of the casting and the presence or absence of gas defects obtained according to the following criteria.

[Evaluation criteria for shape transferability]
A: The hollow part is formed in the same shape as the molded body, and the surface of the hollow part of the casting has gloss.
B: The hollow part is formed in the same shape as the molded body, but the surface of the hollow part of the casting is not glossy.
C: Part or all of the hollow portion does not have the same shape as the molded body.

[Evaluation criteria for gas defects]
A: The presence of gas defects is not recognized on the inner surface of the hollow part.
B: Presence of gas defects is recognized on the inner surface of the hollow part.

<Result>
As shown in Table 2, the obtained casting had sufficient performance.

It is a half sectional view showing one embodiment of a formed object of the present invention. It is a fragmentary sectional view which shows typically one Embodiment of the manufacturing apparatus for enforcing the manufacturing method of the molded object of this invention. It is a fragmentary sectional view which shows typically the supply process of the raw material in one Embodiment of the manufacturing method of the molded object of this invention using the manufacturing apparatus. It is a fragmentary sectional view which shows typically the formation process in one Embodiment of the manufacturing method of the molded object of this invention using the manufacturing apparatus. It is a fragmentary sectional view which shows typically the heat drying process in one Embodiment of the manufacturing method of the molded object of this invention which uses the manufacturing apparatus. It is a fragmentary sectional view which shows typically the demolding process in one Embodiment of the manufacturing method of the molded object of this invention using the manufacturing apparatus. In the manufacturing method of the casting which uses one Embodiment of the molded object of this invention, it is a schematic diagram which shows the state which set this molded object to the main mold | type planarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molded body manufacturing apparatus 2 Mold 2A, 2B Split mold 20 Cavity 21 Gate hole 22 Entrance / exit 3 Core material 30 Tapered part 4 Gate opening / closing means 40 Gate pin 5 Raw material supply means 50 Cylinder 51 Piston 52 Nozzle 10 Molded body 11 (11A) Main type (lower type)
12 Keren 13 Inlet 14 Gas vent

Claims (6)

Inorganic particles, inorganic fibers, thermosetting resin, and BII type viscometer rotor No. 3. A molded article for a mold containing a carboxyvinyl polymer having a 0.1 mass% aqueous solution viscosity at 25 ° C. of 100 to 10000 mPa · s measured at a rotation speed of 60 rpm using 3 .   The molded article for a mold according to claim 1, wherein the inorganic particles include graphite, the inorganic fibers are carbon fibers, and the thermosetting resin is a phenol resin. Furthermore, the thermally expandable particles contain microcapsules encapsulating an expanding agent that expands by vaporization in the shell wall of a thermoplastic resin ,
The thermoplastic resin constituting the shell wall of the microcapsule is polystyrene, polyethylene, polypropylene, polyacrylonitrile, acrylonitrile-vinylidene chloride copolymer, ethylene-vinyl acetate copolymer, or a combination thereof.
The swelling agent included in the microcapsule shell wall is a low boiling point organic solvent selected from propane, butane, pentane, isobutane, and petroleum ether,
The microcapsule is a microcapsule having an average particle diameter before expansion of 5 to 80 μm and a diameter of 3 to 5 times and a volume of 50 to 100 times by heating at 80 to 200 ° C.
The molding for molds according to claim 1 or 2. Inorganic particles, inorganic fibers, thermosetting resin and BII type viscometer rotor No. 3 is filled with a molding raw material obtained by dispersing a carboxyvinyl polymer having a viscosity of 100 to 10,000 mPa · s at 25 ° C. measured at 25 ° C. measured at a rotation speed of 60 rpm in a dispersion medium. A method for producing a molded article for a mold, comprising a step of heating and molding the thermosetting resin to mold the thermosetting resin. The molding raw material further comprises, as thermally expandable particles , microcapsules encapsulating an expansion agent that evaporates and expands in a shell wall of a thermoplastic resin, and is dispersed in the dispersion medium. Having a step of expanding and forming thermally expandable particles;
The thermoplastic resin constituting the shell wall of the microcapsule is polystyrene, polyethylene, polypropylene, polyacrylonitrile, acrylonitrile-vinylidene chloride copolymer, ethylene-vinyl acetate copolymer, or a combination thereof.
The swelling agent included in the microcapsule shell wall is a low boiling point organic solvent selected from propane, butane, pentane, isobutane, and petroleum ether,
The microcapsule is a microcapsule having an average particle diameter before expansion of 5 to 80 μm and a diameter of 3 to 5 times and a volume of 50 to 100 times by heating at 80 to 200 ° C.
The manufacturing method of the molded object for molds of Claim 4.   The manufacturing method of a casting which has the process of casting a molten metal in the molded object for molds in any one of Claims 1-3.

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