CN101222992A - Resin-coated sand for use in cast steel, casting mold made of the sand, steel casting casted using the casting mold - Google Patents
Resin-coated sand for use in cast steel, casting mold made of the sand, steel casting casted using the casting mold Download PDFInfo
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- CN101222992A CN101222992A CNA2006800257334A CN200680025733A CN101222992A CN 101222992 A CN101222992 A CN 101222992A CN A2006800257334 A CNA2006800257334 A CN A2006800257334A CN 200680025733 A CN200680025733 A CN 200680025733A CN 101222992 A CN101222992 A CN 101222992A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
- B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
- B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- B22C1/2246—Condensation polymers of aldehydes and ketones
- B22C1/2253—Condensation polymers of aldehydes and ketones with phenols
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Abstract
A resin-coated san for use in cast steel, comprising a casting sand, a phenolic resin in an amount of 2.5 to 5.0% by weight relative to the amount of the casting sand, potassium nitrate and vinsole. A steel casting manufactured by the casting on a casting mold which is molded using the resin-coated sand can effectively prevent the occurrence of hot-cracking or bath wrinkle even in a thin and large-sized article.
Description
Technical field
The cast steel of coated sand, this coated sand system that the present invention relates to be suitable for cast steel is with casting mold with by the steel casting of this casting mold casting, the cast steel usefulness casting mold that particularly relate to the coated sand of the generation that can reduce steel casting incidental heat cracks of institute and elephant skin (Soup じ わ) effectively, is formed by this coated sand and by the steel casting of this casting mold casting.
Background technology
In recent years, in order to realize lightweight when guaranteeing required intensity such as automobile and building machinery, the steel casting that intensity is high is gazed at.Particularly in order to alleviate the weight of steel casting, the hollow and thin-walled technology of steel casting is established in expectation.In the cast steel field, as this hollow and thin-walled technology, for example known for a long time following illustrated shell moulding etc. are used in various technical fields all the time.
In addition, under the situation of known manufacturing steel casting, the solidification shrinkage amount of the liquation during casting goes out nearly one times greatly than iron castings or aluminium alloy castings etc.For example, make under the situation of the cast steel with hollow structure, because the solidification shrinkage of liquation takes place, this contraction is subjected to forming the constraint of the core (casting mold) of hollow bulb.Therefore, the problem that has foundry goods generation heat cracks.Remove after the heat cracks that takes place in cast steel like this need be cast and be modified to the repairing work of required article shape.For example, as repairing work, the heat cracks portion that occurs in the cast steel is removed by processing such as grinding or channelings earlier.Then, built-up welding is carried out at this position, implemented milled processed etc. again.Thus, can make the cast steel of the required form of having removed heat cracks.
But, if the repairing work of the heat cracks in such cast steel increases, the productivity of cast steel is descended, but also cost is risen, therefore there is the problem of the deterioration that causes economy.In addition, when making the steel casting of complicated shape, exist for the unusual situation of difficult of the repairing work at the position that heat cracks takes place.Under such situation, the casting manipulations of the steel casting that must start anew to carry out again.
In order to tackle such problem, utilize based on carbonic acid gas (CO when for example adopting cast steel with the moulding of casting mold
2The curing of waterglass gas) (sodium metasilicate) be called as CO
2The mode of gas method.In this carbonic acid gas mode, the waterglass as inorganic binder that mixes about 5 weight % with respect to casting mold sand carries out mixing.After should mixing thing moulding,,, casting mold be solidified with sodium silicate gelization by feeding carbonic acid gas.
If use the casting mold by this carbonic acid gas mode moulding to carry out the manufacturing of cast steel, molten liquid steel is injected in the die cavity of casting mold and during solidification shrinkage, can makes inorganic binder softening by the heat of solution.Thus, the employed casting mold sand of casting mold can move in the direction of burying its space underground, and casting mold itself shrinks, and can reduce the restraining force of core for the solidification shrinkage of cast steel.But casting mold (core) casting mold sand when moulding that such carbonic acid gas mode of passing through is shaped is the moisture state that contains moisture.Therefore, when core is shaped, be difficult in core mold filling cast sand equably.And the density height that has casting mold under this situation is to the tendency more than the desired level.
Therefore, even use the casting mold that obtains by the carbonic acid gas mode to cast, casting mold does not fully shrink and can't obtain the situation that prevents effect of heat cracks in the time of also can having the solidification shrinkage of liquation.In addition, owing to use waterglass as binding agent, the casting mold sand that constitutes core during casting is because the heat of liquation and sintering, and core sand sintering securely adheres to.If the such sinter bonded of core sand, then cast cast steel after, very difficulty is removed in the disintegration of core.Therefore, there is the problem that causes productive decline.
On the other hand, as the sculpting method of other cast steel with casting mold, the shell moulding of known dry state.In this shell moulding, casting mold sand lining phenolic resins as organic binder bond, is filled to mould through preheating with the coated sand (RCS) that obtains.The resin that is coated on casting mold sand forms shell by the heat polycondensation of mould.This shell further heated with mould and after it is solidified, with shell from mold releasability, thereby make casting mold.
Under the situation of the casting mold that will make by such shell moulding as the core of steel casting, in the casting process of high temperature, be decomposed as the phenolic resins of binding agent.Therefore, when the hollow bulb of the steel casting after casting takes out core, can make the easy disintegration of core.Therefore, has the advantage that easily to carry out the taking-up of core.
The Japan Patent spy opens to have disclosed in the clear 57-68240 communique (patent documentation 1) and relates to the invention that is used as the phenol resin composition of mold material in such shell moulding.The phenol resin composition that demonstrates low bulk that separated component in the residue that the phenol resin composition of being put down in writing in this patent documentation 1 produces when generating with phenol, bisphenol-A and bisphenol-A or these 3 kinds of compositions of derivative constitute.
Make casting mold by the phenol resin composition that uses such low bulk with shell moulding, the gained casting mold is imbued with pliability, has good adaptability (flexibility).In addition, cast, can suppress the heat cracks of foundry goods and the generation of pore (gas defects) by the casting mold that uses such characteristic.Here, adaptability is meant the character that casting mold shrinks with foundry goods, can tolerate the performance of casting mold of convergent-divergent of the liquation of injection.
In addition, in order to realize the lightweight of steel casting, in the casting of steel casting, require to reduce as far as possible the wall thickness of steel casting in recent years.But, during the cast steel foundry goods,, then have the problem that heat cracks takes place easily if carry out the thin-walled property of foundry goods for lightweight.Therefore, when for example carrying out the manufacturing of Steel Thin-Wall foundry goods, even use with casting mold as the phenol resin composition moulding of the low bulk put down in writing in the patent documentation 1, only by depending on the effect that prevents, be difficult to fully to prevent the heat cracks in the thin-walled cast steel based on the pliability of the casting mold of this resin combination and adaptive heat cracks.Therefore, the particularly manufacturing of Steel Thin-Wall foundry goods wishes to develop the technology that can more effectively prevent the generation of heat cracks.
In addition, make under the situation of Steel Thin-Wall foundry goods, the heat of the liquation of injection is seized by casting mold (core) easily, and flowing of the die cavity inner melt of casting mold may be inhomogeneous.Descend if the mobile variation of liquation and liquation are mobile like this, then exist the surface of the steel casting of casting to produce the problem of concavo-convex elephant skin.Elephant skin are defined as ", poring rate low excessively owing to pouring temperature crossed and waited the elephant skin that see the bottom that cause slowly " in JISG 0588, be classified to 1～5 grade about the generation state of elephant skin.For the problem that elephant skin take place in cast steel like this, for example can't expect to be solved completely by the RCS that is put down in writing in the aforementioned patent document 1, all very wish to develop the more advanced technology that reduces elephant skin effectively all the time.
In addition, though the liquation material is different fully with the casting of aforesaid steel casting, also disclosed the invention of the mold material that the shell moulding in the casting that relates to the foundry goods (for example aluminium) that is formed by nonferrous metal uses in special public clear 31-7256 communique (patent documentation 2) of Japan Patent and the Japanese patent laid-open 9-57391 communique (patent documentation 3).Cast under the situation of such aluminium as non-ferrous casting, known its casting temperature is lower than steel casting.Specifically, casting temperature is about more than 1500～1600 ℃ when making steel casting, and casting temperature is about about 660～700 ℃ during casting aluminium, and is very low.
In the casting of this aluminium,, produced following problem because casting temperature is low.That is, use under the situation of casting mold of making by shell moulding, can not decompose at the binding agent (phenolic resins) of the casting temperature lower mold of aluminium as core.Therefore, under the situation of the aluminium casting of manufacturing hollow, make the back core in the hollow inside that keeps remaining under the high-intensity state foundry goods.Therefore, for core is taken out and make its disintegration in foundry goods, need a large amount of artificial and energy consumptions.
In order to solve such problem, put down in writing in the aforementioned patent document 2 and be used for the technical scheme of RCS as binding agent having added phenolic resins that 0.5～20 weight % gave or transmitted the material (for example lead orthoplumbate or potassium nitrate etc.) of oxygen.Give or transmit the material of oxygen by such use, can promote the decomposition of binding agent, improve the disintegrative of casting mold.For example, implement heat treatment (sand roasting), can make the binding agent thermal decomposition of core by casting mold behind the aluminium casting of casting hollow to the banding pattern core that obtains.Thus, the intensity of core is descended, easily take out core from hollow casting.
In addition, aforementioned patent document 3 is pointed out, by the RCS of record in the patent documentation 2, in the position that can't supply with the low-temperature region of enough heats to casting mold, the disintegrative deficiency of casting mold.So, as the position at such low-temperature region also show the RCS of enough casting mold disintegratives, patent documentation 3 proposed with fire resistance particle, phenolic resins and with the regulation ratio contain oxygen content more than 25 weight % oxygen-containing hydrocarbon compounds (low-grade carboxylic acid's class etc.) and the casting mold disintegrative improving agent of alkali nitrates (potassium nitrate, sodium nitrate etc.) be the RCS of neccessary composition.By making RCS contain such disintegrative improving agent, the disintegrative of casting mold of 300～350 ℃ low-temperature region is improved.
Yet aforementioned patent document 2 and 3 purpose only are to make the disintegrative as the casting mold of the low nonferrous metal of above-mentioned casting temperatures such as aluminium to improve.Therefore, do not discuss fully, the not special record of concrete grammar of the generation that suppresses heat cracks and elephant skin for the problem of heat cracks that takes place in the foundry goods that relates to casting and elephant skin.
In addition, in these patent documentations 2 and 3, the material that improves as the disintegrative that makes core, all example potassium nitrate.This potassium nitrate is known as powder composition, is to have volatile material.In addition, known potassium nitrate is sintering through the heating more than 900 ℃.
Therefore, the casting mold (core) that in the past will contain potassium nitrate is used for the casting that pouring temperature exceeds the many steel castings of the casting of aluminium and has hidden danger for the security in the explosive operation of potassium nitrate.In addition, think that potassium nitrate sintering and the intensity of casting mold is improved under the casting temperature more than 900 ℃ then worsens the disintegrative of the core after the casting if make cast steel contain potassium nitrate with casting mold.Based on these reasons, though potassium nitrate in patent documentation 2 and the 3 described castings that are used for aluminium as described above in the past, is incogitable for pouring temperature using potassium nitrate considerably beyond the casting of 900 ℃ the steel casting more than 1500 ℃.
Patent documentation 1: the Japan Patent spy opens clear 57-68240 communique
Patent documentation 2: the special public clear 31-7256 communique of Japan Patent
Patent documentation 3: Japanese patent laid-open 9-57391 communique
The announcement of invention
The present invention finishes in order to solve aforesaid existing issue, and its specific purposes are to be provided at and can prevent the generation of heat cracks in the manufacturing of the cast steel with hollow structure and reduce coated sand that the cast steel of the generation of elephant skin uses effectively, use casting mold that this sand molding obtains and by the steel casting of this casting mold casting.
To achieve these goals, the inventor has carried out various experiments repeatedly.Found that, even in the casting of the high steel casting of the casting temperature that was not contemplated to fully, in the coated sand that its core is used, mix the danger that alkali nitrates and vinsol (Vinsol) do not have blast fully yet, and its adaptability improves significantly in the past.
That is, the topmost of coated sand provided by the present invention be characterised in that, as basic formation, comprises casting mold sand, with respect to this casting mold sand be 2.5～5.0 weight % phenolic resins, potassium nitrate and vinsol.
In addition, in the coated sand of the present invention, better be at least a kind of the phenol composition of the aforementioned phenolic resins derivative that comprises the residue that generates in the purifying that is selected from bisphenol-A, this bisphenol-A and the separated component in this residue.
In addition, the incorporation that better is aforementioned potassium nitrate is 2～50 weight %, and the incorporation of aforementioned vinsol is 4.0～20 weight % with respect to aforementioned phenolic resins.
In addition, cast steel provided by the present invention is with the principal character of casting mold, and it is thick 6～15mm, have 1000cm
2The casting mold of the steel casting of above surface area uses aforementioned resin coating sand molding of the present invention to form.Under this situation, the calorific intensity that better is aforementioned casting mold is 120～175N/cm
2
In addition, the principal character of steel casting provided by the present invention is, the steel casting that it is to use aforementioned cast steel of the present invention to cast with casting mold, and the thickness of this steel casting is 6～15mm, has 1000cm
2Above surface area, the heat cracks that the foundry goods face that contacts with aforementioned casting mold takes place is below 70mm.
In addition, steel casting of the present invention has 1～2 grade the better quality of being classified as based on JIS G 0588 of elephant skin.In addition, the weight of steel casting of the present invention better is more than 35kg.
Coated sand of the present invention (RCS) comprises casting mold sand, with respect to this casting mold sand be 2.5～5.0 weight % phenolic resins, potassium nitrate and vinsol.
The present inventor makes does not as previously mentioned have used potassium nitrate fully in the casting that contains steel casting among the RCS, various experiments have been carried out in the casting of the steel casting that adopts the casting mold that forms with this RCS moulding.Finally, contain potassium nitrate when containing phenolic resins with the regulation ratio different, obtained following result with aforementioned patent document 2 and 3 by making among the RCS.That is, find in the casting of pouring temperature far above the steel casting more than 1500～1600 ℃ of the casting of aluminium of liquation the danger of the potassium nitrate blast that does not exist in the past to be worried.In addition, even also confirm to make cast steel contain potassium nitrate with casting mold, the harmful effect that does not occur also that the sintering of potassium nitrate produces to the disintegrative of casting mold.Moreover, find first to contain potassium nitrate among the RCS and make the cast steel casting mold by making, as described below, for heat cracks prevent with the inhibition of elephant skin very effectively, can obtain unexpected special result.
Potassium nitrate is at sintering more than 900 ℃ though this is considered to, but under the manufacturing temperature of steel casting far above this, the potassium nitrate of sintering produces the heating that spontaneous combustion causes and when keeping high temperature, promote the carbonization of phenolic resins, even thereby the about 2 times amount of contraction with aluminium and iron class is shunk during the liquation cooling curing, casting mold itself adapts to this variation well and shrinks, and keeps foundry goods securely, and so-called adaptability improves.Its result is, even thin-walled and large-scale hollow casting, also extremely difficult generation heat cracks.In addition, simultaneously the self-heating of potassium nitrate also with the temperature maintenance of casting mold periphery at high temperature, so liquation flows and can not stagnate in the part, the generation of elephant skin also significantly reduces.
Among the present invention, except adding aforementioned potassium nitrate, also add vinsol.The vinsol resin is dead color, dystectic thermoplastic of being derived by pine tree, and the goods of U.S. He Kuersi powder company (HerculesPowder Company) system are on sale on market.Can three-dimensionally not solidify even this vinsol resin is heated yet, therefore have buffering effect.In order further to improve resiliency, can also be also with a small amount of petroleum resinoid or rosin etc.Among the present invention, the interpolation of vinsol promotes the softening of shell casting mold by being heated, the adaptability for cast steel is further improved.On the other hand, there is the tendency as the calorific intensity rising of resin in vinsol, and liquation must be controlled to be the low calorific intensity of the degree till shape to the liquation that keeps casting mold solidifies when injecting.By adding potassium nitrate as mentioned above, control the calorific intensity of vinsol efficiently here.That is, the interpolation of potassium nitrate and vinsol is that the shape of the casting mold when above-mentioned adaptability and liquation are solidified keeps the necessary condition of the common performance of these two kinds of functions.
That is, if aforesaid RCS of the present invention, then form casting mold (core) and use this casting mold (core) when casting by shell moulding, can by potassium nitrate and vinsol act on the liquation solidification shrinkage time to make the casting mold distortion suitable opportunity.In addition, behind the injection molten liquid steel, can promote the thermal decomposition of phenolic resins, the intensity of casting mold is descended.Thus, during the liquation solidification shrinkage, it shrinks the constraint that is not subjected to casting mold, therefore can prevent cast steel generation heat cracks.
In addition, contain potassium nitrate, can make casting mold heating from the time in casting by making RCS as mentioned above.Thus, when liquation is injected casting mold, when preventing the decline of liquation flowability, can make the uniform heat distribution of liquation.Therefore, can suppress the generation of elephant skin, obtain to have the steel casting of good cast(ing) surface.The incorporation of potassium nitrate at this moment better is 2～50 weight % with respect to phenolic resins.If below 2 weight %, then the self-heating amount is low excessively, the liquation during cast flows and has some setbacks, and causes the generation of elephant skin; If more than 50 weight %, then the self-heating amount is excessive, phenolic resins generation thermal decomposition, the very easily disintegration that becomes can't realize neat and well spaced casting.
In addition, among the present invention, the phenol composition of phenolic resins comprises at least a kind of derivative of the residue that generates in the purifying that for example is selected from bisphenol-A, this bisphenol-A and the separated component in this residue.By containing such phenolic resins, can give casting mold good adaptability.Thus, can when casting, make casting mold more suitably follow the solidification shrinkage distortion of liquation, can prevent the generation of heat cracks very effectively.
In addition, RCS of the present invention also comprises vinsol.Thus, the adaptability of casting mold is improved, therefore can more effectively prevent the generation of heat cracks.Under this situation, the incorporation of vinsol better is 4.0 weight %～20 weight % with respect to phenolic resins.If be less than 4.0 weight %, then can't expect required adaptive raising; If surpass 20 weight %, then calorific intensity is low excessively, the casting mold easy disintegration that becomes, and the foundry goods of finishing also is difficult to obtain required shape.
By cast steel casting mold provided by the invention is to be used for thick 6～15mm, to have 1000cm
2The casting mold of the casting of the steel casting of above surface area uses aforementioned RCS moulding of the present invention.By using such cast steel to cast with casting mold, as previously mentioned, can prevent the generation of heat cracks and elephant skin, make steel casting with good cast(ing) surface.
In addition, the calorific intensity of casting mold of the present invention is 120～175N/cm
2Therefore, suitably keep the shape of casting mold during injection that can molten liquid steel, stably make cast steel with required form.
Steel casting of the present invention for thick 6～15mm of using aforementioned cast steel to cast with casting mold, have 1000cm
2The steel casting of above surface area.In addition, be the good foundry goods of the quality of heat cracks below 70mm that the foundry goods face that contacts with casting mold takes place.
Particularly, steel casting of the present invention is that the generation of elephant skin is suppressed to 1～2 grade high-quality foundry goods in the classification based on JIS G 0588.
In addition, aforementioned steel casting is manufactured into weight more than 35kg.Though such steel casting is also according to the material of cast steel and difference, for example average wall thickness reaches 4000cm for the surface area of steel casting under the situation of about 10mm
2More than.The amount of contraction of Steel Thin-Wall foundry goods when casting of the larger-size hollow structure with the above weight of 35kg like this is big, and therefore heat cracks took place in the past easily.Yet the present invention is very useful for such Steel Thin-Wall foundry goods, can suppress the generation of heat cracks and elephant skin effectively.
The simple declaration of accompanying drawing
Fig. 1 represents to adopt the front elevation of the assay method of thermal flexibility amount determining device for medelling.
Fig. 2 represents the medelling sectional view of the structure of casting mold for medelling.
Fig. 3 (a) represents the front elevation of the large-scale steel casting cast for medelling, for being the sectional view in cross section with the face vertical with respect to the thickness direction of this large-scale steel casting, (c) be the sectional view of the I-I shown in (a) (b).
Fig. 4 (a) represents the sectional view of the medium-sized steel casting cast for medelling, (b) be the sectional view of the II-II shown in (a), (c) is the sectional view of the III-III shown in (a).
Fig. 5 (a) represents the front elevation of the small-sized steel casting cast for medelling, (b) be the side view of this small-sized steel casting, (c) is the ground plan of this small-sized steel casting.
The copy of the photo that the generation state of the elephant skin that take place in the large-scale steel casting of Fig. 6 for observation embodiment 4 and comparative example 2 gets.
The figure of the length of the elephant skin that take place in the large-scale steel casting of Fig. 7 for comparing embodiment 4 and comparative example 2.
The explanation of symbol
1: principal mode, 2: core, 3: mo(u)ld top half, 4: mo(u)ld bottom half, 5: sprue, 10: thermal flexibility amount determining device, 11: large-scale steel casting (carriage), 12: medium-sized steel casting (framework), 13: small-sized steel casting (small-sized carriage), H: heater.
The best mode that carries out an invention
Below, the preferred embodiment of the present invention is elaborated.
RCS in the preferred embodiment of the present invention comprises casting mold sand, with respect to this casting mold sand phenolic resins that is 2.5～5.0 weight %, be the potassium nitrate of 2.0～50 weight % and be the vinsol of 4.0～20 weight % with respect to this phenolic resins with respect to this phenolic resins.
As aforementioned casting mold sand, can use the common used fire resistance casting mold sand of casting mold all the time.This casting mold sand can be natural sand or artificial sand, is not particularly limited.As concrete example, for example can exemplify silica sand, olivine sand, zircon sand, chromite sand, emergy, ferrochrome class slag, dilval class slag, converter slag, the artificial particle of mullite class (for example trade name " Naigai CERABEADS " that can buy from ITOCHU ceramics Co., Ltd. (ITOCHU セ ラ テ Star Network Co., Ltd.)) and their reclaimed sand etc.They may be used alone, two or more kinds can also be used in combination.In addition, in these casting mold sand, better be to use silica sand, good especially is that combination silica sand and reclaimed sand use.In addition, by mixing zircon sand, the sintering in the time of can preventing to cast adheres to.
Here, reclaimed sand is meant that taking casting mold apart collect the back casting mold piece pulverizes with known pulverizers such as crushing machines, the regeneration that the sand grains body that obtains is implemented regulation handle and sand.In addition, handle as regeneration, can exemplify usually by grinding the abrasion formula regeneration of removing the attachment that is attached to casting mold sand surface handle, by implementing that roasting formula regeneration that heat treatment removes is handled etc.But the present invention is not limited to these and handles, so long as can remove the attachment of casting mold sand, can adopt known in the past any processing.
Aforementioned phenolic resins plays the effect in conjunction with the binding agent of the particle that keeps casting mold sand.As phenolic resins,, be not particularly limited so long as be main component and have existing or do not exist the resin of the character that is heating and curing under the condition of curing agent to get final product with the reaction product of phenols and aldehydes.
The incorporation of this phenolic resins is 2.5～5.0 weight % with respect to casting mold sand, better is 2.7～3.5 weight %.Phenolic resins during less than 2.5 weight %, can't give casting mold enough intensity with respect to the content of casting mold sand, causes that easily moulding is bad.In addition, during the cast steel foundry goods, casting mold breaks, occurs being called as the problem of the casting defect of burr (veining) easily when having cast on foundry goods.
On the other hand, if phenolic resins surpasses 5.0 weight % with respect to the content of casting mold sand, then with the mixing difficulty of casting mold sand.In addition, during casting, because the gasification of phenolic resins, the generating capacity of gas increases.Thus, exist the steel casting of making that the problem of a large amount of gas defects takes place.
As the object lesson of phenolic resins, can exemplify novolac-type phenolic resins, fusible type phenolic resins, nitrogenous fusible type phenolic resins, methyl phenyl ethers anisole class phenolic resins, low bulk phenolic resins and these phenolic resins and mix with for example epoxy resin, Lauxite, melmac, xylene resin, polyamide, epoxy compounds, melamine compounds, urea compound etc. or react and phenol-formaldehyde resin modified of generating etc.
These phenolic resins may be used alone, two or more kinds can also be used in combination.In addition, use novolac-type phenolic resins etc. not have under the situation of resin of self-curing separately, must and give Thermocurable during making molds with curing agent such as for example hexas.Under this situation, the incorporation of hexa better is about 5～12 weight % with respect to phenolic resins.Use form for phenolic resins is not particularly limited, but is generally the solid of suitable shape, can use resin liquid or solution as required.In addition, can also solid-liquid and usefulness.
Aforementioned phenolic resins comprises 30～90 weight %, better is the low bulk phenolic resins of 50～80 weight %.As this low bulk phenolic resins, at least a kind of derivative that comprises the residue that generates in the purifying that is selected from bisphenol-A, this bisphenol-A and the separated component in this residue gets final product, and for example can use the phenolic resins that is disclosed in the aforementioned patent document 1.
Comprise the such low bulk phenolic resins of 30～90 weight % by phenolic resins, can make casting mold have good adaptability when making casting mold.Under this situation, if the content of low bulk phenolic resins surpasses 90 weight %, then during making molds because the decline of the curing rate of phenolic resins may cause that moulding is bad.On the other hand, if the content of low bulk phenolic resins less than 30 weight %, burr takes place in cast steel easily when then casting.
In addition, above-mentioned phenolic resins also can be used in combination with the amine of the quality improving of intensity that helps casting mold and lubricity etc., epoxies, vinyl-based silane coupler and/or lubricant.Representative example as aforementioned silane coupler, can exemplify gamma-aminopropyl-triethoxy-silane, N-β-(aminoethyl)-γ-An Bingjisanjiayangjiguiwan, γ-glycidoxypropyltrime,hoxysilane, β-(3,4-epoxy radicals cyclohexyl)-ethyl trimethoxy silane, vinyltrimethoxy silane, vinyl three ('beta '-methoxy) silane, vinyl ('beta '-methoxy ethyoxyl) silane etc.In addition, the representative example of aforementioned lubricants can the exemplified by ethylene bis-stearamides, di-2-ethylhexylphosphine oxide stearmide, hydroxyl stearmide, methylol stearmide etc.
Is 2～50 weight % as the incorporation of the potassium nitrate of one of neccessary composition of present embodiment based on the weight of phenolic resins (solid constituent conversion), better is 3～25 weight %, is more preferably 5～20 weight %.If potassium nitrate, then can't obtain enough heat cracks and prevent effect less than 2 weight % with respect to the content of phenolic resins.On the other hand, if surpass 50 weight %, mould strength deficiency then, it is bad to produce moulding.In addition, consider the security for blast when RCS makes, the content of potassium nitrate also better is below 50 weight %.
The incorporation of vinsol better is 10～20 weight % based on the weight of phenolic resins (solid constituent conversion), is more preferably 10～15 weight %.Thus, can further improve the adaptability of casting mold.Therefore, can more effectively prevent the generation of heat cracks.As vinsol, for example can use rosin extract or rosin to extract gum residue, concrete as trade name " Vinsolresin " (acid number 95) that lotus Ke Suersi company (Herxules society) makes etc.Under this situation,, then can't expect adaptive raising based on vinsol if vinsol is less than 4.0 weight % with respect to the content of phenolic resins.On the other hand, if surpass 20 weight %, then the calorific intensity of casting mold is low excessively, or gas defects appears in cast steel easily when casting.
In addition, among the RCS of present embodiment, except mentioned component, can also be as required suitably mix various additives, for example fixed agent, releasing agent, deodorant, iron oxide red, the placer iron etc. of preventing such as calcium stearate with the amount of regulation.
In addition, aforesaid cast steel can be made by the preparation method of implementing at present in the art of RCS, for example the whole bag of tricks such as the hot method with plastic film of dry method, half hot method with plastic film, cold method with plastic film, powder solvent method.Wherein, from viewpoints such as productivity, qualities, it is desirable to use the hot method with plastic film of dry method especially.
For example, in mixing rolls such as sand muller, pack into, adjust temperature through the casting mold sand of preheating.Then, in mixing roll, supply with other necessary additive, the melting mixing stipulated time, form block with ormal weight.Then, mix down add the hexa aqueous solution in the air-supply cooling, make the block disintegration become sand shape after, it is mixing to add calcium stearate.Thus, can obtain the cast steel RCS of aforesaid present embodiment.In addition, when supplying with potassium nitrate, the angle of the security during from processing better is that the aqueous solution of making debita spissitudo uses, and for example concentration is the aqueous solution about 10～50 weight %.
Then, use aforesaid cast steel RCS, carry out moulding, thereby can obtain to have the cast steel casting mold of required form according to shell moulding.The casting mold of the present invention that obtains like this for thick 6～15mm, surface area at 1000cm
2The casting of above steel casting is very useful.
That is, use under the situation that such cast steel casts as core with casting mold, the adaptive raising by based on the casting mold of the effect of aforementioned potassium nitrate and low bulk phenolic resins and vinsol can prevent the steel casting generation heat cracks of being cast.In addition, the casting mold of present embodiment contains potassium nitrate, thereby can make the casting mold self-heating when casting.Thus, when in casting mold, injecting molten liquid steel, can prevent the decline of liquation flowability, suppress cast steel generation elephant skin effectively, make steel casting with good cast(ing) surface.In addition, among the present invention, cast steel is not limited to aforesaid core with casting mold, also can be shaped to principal mode.In addition, also be not particularly limited, can suitably select according to the service condition of casting mold etc. for the concrete moulding condition of casting mold etc.
Such cast steel for example reaches 120～175N/cm with the calorific intensity of the casting mold in when casting with casting mold
2Condition constitute.Casting mold has such calorific intensity, thereby can keep the shape of casting mold when molten liquid steel injects, and casting stably has the steel casting of required form.
In addition, for the cold strength of cast steel, with 900～1400N/cm with casting mold
2, better be 1000～1360N/cm
2Condition constitute.If the cold strength of casting mold is less than 900N/cm
2, burr takes place in cast steel easily when then casting.On the other hand, if cold strength surpasses 1400N/cm
2, then gas defects takes place in foundry goods easily.
In addition, using the thickness of the steel casting that aforesaid cast steel casts with casting mold is 6～15mm, and surface area is at 1000cm
2More than.And, be the every 1000cm of heat cracks that the foundry goods face that contacts with casting mold takes place
2Surface area be the following good foundry goods of quality of 70mm.In addition, in such steel casting, effectively being suppressed of elephant skin, the generation that for example has elephant skin is to count 1～2 grade cast(ing) surface well based on the classification of JIS G 0588.
Embodiment
Below, exemplify embodiment the present invention is carried out more specific description.In addition, among the following embodiment,, carry out following test respectively, its characteristic is estimated for each RCS that makes.
The mensuration of＜cold strength and calorific intensity 〉
RCS is configured as the size of 30mm φ * 50mm,, makes 2 samples 1 (TP1) 250 ℃ of sintering 2 minutes.After a TP1 is put and is chilled to normal temperature, its compressive resistance is measured as cold strength.In addition, another TP1 measures the compressive resistance after its heating just 1000 ℃ of anxious heat 1 minute as calorific intensity.
The mensuration of＜coefficient of thermal expansion 〉
Coefficient of thermal expansion is measured according to JACT test method(s) M-2.That is,, measure the length (TP before the anxious heat is long) of this TP1 with the aforementioned TP1 that similarly makes 30mm φ * 50mm.Then, TP1 being arranged at adjustment in the stove is in 1000 ℃ the high temperature casting mold sand test machine.Then, in this testing machine, measure the length (TP after the anxious heat is long) of TP, calculate the coefficient of thermal expansion of each time based on this measurement result by following calculating formula every the stipulated time.
TP long * 100 before coefficient of thermal expansion (%)=(TP before the TP length-urgency heat after the anxious heat is long)/anxious heat
＜adaptive evaluation 〉
After RCS being configured as the size of 50 * 120 * 5mm,, make TP2 250 ℃ of sintering 40 seconds.The TP2 that obtains is fixed in thermal flexibility amount determining device 10 with the fixing state of an end as shown in Figure 1.Then, with pre-heated heater H insert TP2 below, carry out anxious heat, the free end of measuring TP2 upward displacement displacement and corresponding to the hot time of the urgency of this displacement.
The evaluation of＜heat cracks 〉
Use casting mold sand by greensand mold manufactured principal mode 1 as shown in Figure 2.In addition, use RCS to make sample core 2 by shell moulding.In addition, principal mode 1 can be divided into mo(u)ld top half 3 and mo(u)ld bottom half 4 up and down, and forms the state formation in the space of drum with inside.
Then, on coaxial, sample core 2 is installed in the inner space of the principal mode 1 that obtains.Then, inject molten liquid steel from sprue 5 with rising pouring, cast thickness is the steel casting of the drum of about 10mm.At this moment, molten liquid steel uses the material that is equivalent to low-alloy steel steel-casting SCSiMn2, and the pouring temperature of molten liquid steel is made as 1550 ± 10 ℃, casts.The weight of casting the steel casting that obtains like this is 35kg, and the surface area of thinner wall section is 4260cm
2
After the casting, observable steel casting is measured the longest one of be full of cracks length in the heat cracks that steel casting takes place.In addition, the detection of heat cracks is implemented according to the crank detection test method of soaking into of JIS Z 2343 defineds.Based on the measured value of this be full of cracks length, by 5 grades of following evaluations of carrying out heat cracks.In addition, for the heat cracks that detects, calculate every 1000cm
2The be full of cracks length of steel casting surface area.
The evaluation criterion of heat cracks: be full of cracks length gives the evaluation of " 5 " when being 0mm (no heat cracks), be full of cracks length being evaluated as below 100mm " 4 ", surpass be evaluated as " 3 " below 100mm, the 200mm, surpass be evaluated as " 2 " below 200mm, the 300mm, surpass be evaluated as " 1 " of 300mm.
The evaluation of＜elephant skin 〉
Cast steel foundry goods similarly during with the evaluation of aforementioned hot be full of cracks, the steel casting that obtains by perusal.Then, steel casting is not almost found be evaluated as " zero " of elephant skin will to observe be evaluated as " * " of elephant skin.
[embodiment 1]
In sand muller (far away state ironworker Co., Ltd. (Far state iron worker Co., Ltd.) system) in drop into 7kg and be preheated to Japan of 150 ℃ and produce silica sand, (Xu You Machine material Industrial Co., Ltd of 210g Asahi Organic Chem Ind) the novolac-type phenolic resins (trade name " SP6905 " made; Below note is made novolac resin A), the trade name " Vinsol resin " of 21g potassium nitrate, 40g lotus Ke Suersi company (Herxules society), with they mixing 40 seconds.Then, the 20g hexa is dissolved in the 105g water and the aqueous solution join in this sand muller.Then, when blowing by air blast, mixing block disintegration to sand is granular.Then, in this sand muller, add the 7g calcium stearate after, mixing again 5 seconds, thus obtain RCS.
[embodiment 2～7 and comparative example 1～3]
For embodiment 2～7 and comparative example 1～3,, similarly make RCS respectively with previous embodiment 1 except proportioning and its composition with RCS change to the incorporation shown in following table 1～3.In addition, in table 1～3, novolac resin B is the (Xu You Machine material Industrial Co., Ltd of Asahi Organic Chem Ind that shows low bulk) the novolac-type phenolic resins of trade name " SP500HS " of system, novolac resin C is for as the (Xu You Machine material Industrial Co., Ltd of Asahi Organic Chem Ind that shows the novolac-type phenolic resins of low bulk) trade name " BP150 " of system.
Example 1 in the past
As example 1 in the past, do not adopt shell moulding, make the mixing sand of the moulding of carrying out casting mold by normal temperature self-curing method.At first, in mixer on 0.9kg Japan product silica sand and the 2.1kg reclaimed sand input labware river Zhuo, add the Asahi Organic Chem Ind (Xu You Machine material Industrial Co., Ltd of 9g as the organosilane ester curing agent) trade name " E40 " of system, mixing 30 seconds.Then, add the alkaline resole resin of 45g through adjusting, mixing again 30 seconds, thus obtain mixing sand.The mixing sand that obtains is shaped, it is solidified at normal temperatures, thereby can make each sample with regulation shape.
Example 2 in the past
As example 2 in the past, pass through CO
2Gas method is made the mixing sand that carries out making molds.At first, in mixer on 1.5kg Japan product silica sand and the 1.5kg reclaimed sand input labware river Zhuo, add 165g waterglass, mixing 1 minute.The mixing sand that obtains is filled in the mould, uses carbonic acid gas that it is solidified, thereby can make each sample with regulation shape.In addition, solidify each sample from mould that obtains and take out back placement 24 hours, supply again in each mensuration and evaluation.
For the foregoing description 1～7, comparative example 1～3 and the sample of example 1,2 in the past, carry out the mensuration of cold strength, calorific intensity and coefficient of thermal expansion and the evaluation of adaptability, heat cracks and elephant skin, it the results are shown in following table 1～3.
[table 1]
| | Embodiment | 1 | |
Embodiment 3 | |
||
| The sand kind | - | Japan produces silica sand | Japan produces silica sand | Japan produces silica sand: reclaimed sand=50%: 50% | Japan produces silica sand: reclaimed sand=50%: 50% | ||
| The resin kind | Novolac resin | Novolac resin A | Novolac resin B | Novolac resin B | Novolac resin C | ||
| Curing agent | - | Hexa | Hexa | Hexa | Hexa | ||
| Potassium nitrate | (weight %/resin) | 10 | 10 | 10 | 10 | ||
| Vinsol | (weight %/resin) | 20 | 10 | 10 | 10 | ||
| Cold strength | (N/cm 2) | 960 | 1352 | 1232 | 1280 | ||
| Calorific intensity | (N/cm 2) | 98 | 105 | 168 | 170 | ||
| Coefficient of |
1 minute | ％ | 0.48 | 0.5 | 0.42 | 0.35 | |
| 2 minutes | ％ | 1.03 | 1.06 | 0.64 | 0.58 | ||
| 3 minutes | ％ | 1.20 | 1.23 | 0.79 | 0.76 | ||
| 4 minutes | ％ | 1.28 | 1.33 | 0.79 | 0.76 | ||
| Adaptability | Time till fractureing (second) | 98 | 100 | 100 | 70 | ||
| Displacement (mm) | 2.7 | 3.3 | 3.3 | 3.3 | |||
| The evaluation of steel casting | Heat cracks is estimated | 4 | 4 | 4 | 5 | ||
| Generation ratio (the mm/1000cm of be full of cracks 2) | 25 | 23 | 23 | 0 | |||
| Elephant skin | ○ | ○ | ○ | ○ | |||
[table 2]
| | Embodiment | 5 | Embodiment 6 | Embodiment 7 | ||
| The sand kind | - | Japan produces silica sand: reclaimed sand=50%: 50% | Japan produces silica sand: reclaimed sand=50%: 50% | Japan produces silica sand: reclaimed sand=50%: 50% | ||
| The resin kind | Novolac resin | Novolac resin C | Novolac resin C | Novolac resin C | ||
| Curing agent | - | Hexa | Hexa | Hexa | ||
| Potassium nitrate | (weight %/resin) | 10 | 10 | 20 | ||
| Vinsol | (weight %/resin) | 5 | 15 | 20 | ||
| Cold strength | (N/cm 2) | 1340 | 1220 | 980 | ||
| Calorific intensity | (N/cm 2) | 182 | 125 | 95 | ||
| Coefficient of |
1 minute | ％ | 0.38 | 0.33 | 0.30 | |
| 2 minutes | ％ | 0.63 | 0.54 | 0.50 | ||
| 3 minutes | ％ | 0.79 | 0.70 | 0.65 | ||
| 4 minutes | ％ | 0.79 | 0.70 | 0.65 | ||
| Adaptability | Time till fractureing (second) | 85 | 63 | 50 | ||
| Displacement (mm) | 2.8 | 3.6 | 3.9 | |||
| The evaluation of steel casting | Heat cracks is estimated | 4 | 5 | 5 | ||
| Generation ratio (the mm/1000cm of be full of cracks 2) | 10 | 0 | 0 | |||
| Elephant skin | ○ | ○ | ○ | |||
[table 3]
| Sample | Comparative example 1 | Comparative example 2 | Comparative example 3 | Example 1 in the past | Example 2 in the past | ||
| The sand kind | - | Japan produces silica sand | Japan produces silica sand | Japan produces silica sand | Japan produces silica sand: reclaimed sand=30%: 70% | Japan produces silica sand: reclaimed sand=30%: 70% | |
| The resin kind | Novolac resin | Novolac resin A | Novolac resin A | Novolac resin B | The alkalescence resole resin | Waterglass | |
| Curing agent | - | Hexa | Hexa | Hexa | The acetate glycol ester | CO 2 | |
| Potassium nitrate | (weight %/resin) | 10 | 0 | 0 | 0 | 0 | |
| Vinsol | (weight %/resin) | 0 | 0 | 10 | 0 | 0 | |
| Cold strength | (N/cm 2) | 1122 | 1409 | 1479 | 333 | 245 | |
| Calorific intensity | (N/cm 2) | 149 | 178 | 181 | 20 | 20 | |
| Coefficient of |
1 minute | ％ | 0.69 | 0.74 | 0.5 | 0.33 | 0.44 |
| 2 minutes | ％ | 1.18 | 1.23 | 1.08 | 0.45 | 0.5 | |
| 3 minutes | ％ | 1.37 | 1.48 | 1.25 | 0.77 | 0.55 | |
| 4 minutes | ％ | 1.37 | 1.55 | 1.32 | 1.09 | 0.61 | |
| Adaptability | Time till fractureing (second) | 180 | 280 | 150 | 145 | 70 | |
| Displacement (mm) | 1.5 | 1.5 | 3.3 | 3 | 4 | ||
| The evaluation of steel casting | Heat cracks is estimated | 2 | 1 | 2 | 1 | 4 | |
| Generation ratio (the mm/1000cm of be full of cracks 2) | 67 | Surpass 70mm | Surpass 70mm | Surpass 70mm | 23 | ||
| Elephant skin | △ | × | × | × | × | ||
In above-mentioned table 1～3, by embodiment 1～7 and comparative example 1～3 more as can be known, only by making RCS contain in potassium nitrate and the vinsol any, can't suppress simultaneously the generation of heat cracks and elephant skin generation the two.Particularly can also confirm to contain potassium nitrate and vinsol among the RCS, adaptability is improved, more effectively suppress the generation of heat cracks by making.In addition, by embodiment 1～4 also as can be known, the heat cracks of RCS that contains the phenolic resins of potassium nitrate, vinsol and low bulk prevents that effect is remarkable.Particularly, can make the very high-quality steel casting that heat cracks and elephant skin do not take place by using the RCS of embodiment 4～7.
Here, by embodiment 1～7 and comparative example 1 as can be known, particularly among the present invention vinsol mix the bigger contribution that prevents for adaptive raising and heat cracks.By comparative example 1 as can be known, do not mix vinsol and when only mixing potassium nitrate, the adaptability deterioration, the evaluation of heat cracks also is low to moderate " 2 ", by comparative example 3 as can be known, do not mix potassium nitrate and general to adaptive effect yet, but can't avoid the generation of heat cracks and elephant skin by mixing vinsol.Here, if only see the incorporation of vinsol with respect to phenolic resins, if vinsol is less than 5 weight %, then as can be known by comparative example 1 and 2, and the adaptability deterioration, the generation of heat cracks is many.On the other hand, if the incorporation of vinsol surpasses 20 weight %, then calorific intensity is low excessively, the easy disintegration of casting mold, and the foundry goods of finishing also is difficult to obtain required form.
Then,, make the core of regulation shape respectively, use this core casting large-scale steel casting 11 (carriage) as shown in Figure 3 with actual article shape for the RCS of previous embodiment 3,4 and comparative example 2 and the mixing sand of example 1,2 in the past.In addition, Fig. 3 (b) is for being the sectional view in cross section with the vertical face of thickness direction with respect to the carriage 11 shown in Fig. 3 (a), and Fig. 3 (c) is the sectional view of the I-I shown in Fig. 3 (a).The average wall thickness of the carriage 11 that obtains is about 12mm, and the surface area of thinner wall section is 15200cm
2
In addition, when making carriage shown in Figure 3, principal mode is by the greensand mold manufactured.In addition, inject the material that is equivalent to structure usefulness low-alloy cast steel spare SCSiMn2 as molten liquid steel in casting mold, the pouring temperature of liquation at this moment is made as 1550 ± 10 ℃.
For each carriage 11 that obtains,, measure the length of the heat cracks that detects according to the crank detection test method of the soaking into detection heat cracks of JIS Z 2343 defineds.In addition, calculate every 1000cm
2The generation ratio of the be full of cracks of thinner wall section surface area.In addition, the elephant skin that take place for carriage are estimated based on the outward appearance test method and the classification on the steel casting surface of JIS G 0588 regulation.
On the other hand, for previous embodiment 2 and comparative example 2, cast medium-sized steel casting 12 (framework) shown in Figure 4 and small-sized steel casting 13 (small-sized carriage) shown in Figure 5.In addition, when casting shown in Figure 4 medium-sized steel casting, use as molten liquid steel to be equivalent to the material of Welding Structure with carbon steel steel-casting SCW450, the pouring temperature of liquation is made as 1550 ± 10 ℃.On the other hand, when casting shown in Figure 5 small-sized steel casting, use as molten liquid steel to be equivalent to the material of structure with low-alloy cast steel spare SCSiMn2, the pouring temperature of liquation is made as 1550 ± 10 ℃.Other of medium-sized and small-sized steel casting created conditions about these, and be identical with the situation of aforementioned large-scale steel casting.
The average wall thickness of the medium-sized steel casting 12 that obtains is about 11mm, and the thinner wall section surface area is 7000cm
2This medium-sized steel casting 12 is very difficult to carry out the parts of the repairing work of heat cracks when be that hollow is inner heat cracks takes place.For this medium-sized steel casting, same with aforementioned large-scale steel casting, to the length of heat cracks, every 1000cm
2These 3 of the generation ratio of the be full of cracks of thinner wall section surface area and the generation states of elephant skin are estimated.
On the other hand, the average wall thickness of small-sized steel casting 13 is about 12mm, and the thinner wall section surface area is 2160cm
2For this small-sized steel casting, the length of heat cracks and these 2 of the generation states of elephant skin are estimated.
Here, the result who estimates for above-mentioned large-scale, medium-sized, small-sized steel casting sums up and is shown in following table 4.
[table 4]
| | Embodiment | 2 | Embodiment 3 | Comparative example 2 | Example 1 in the past | Example 2 in the past | ||
| The sand kind | - | Japan produces silica sand | Japan produces silica sand: reclaimed sand=50%: 50% | Japan produces silica sand | Fresh sand: reclaimed sand=30%: 70% | Fresh sand: reclaimed sand=70%: 30% | ||
| The resin kind | Novolac resin | Novolac resin B | Novolac resin C | Novolac resin A | The alkalescence resole resin | Waterglass | ||
| Curing agent | - | Hexa | Hexa | Hexa | The acetate glycol ester | CO 2 | ||
| Potassium nitrate | (weight %/resin) | 10 | 10 | 0 | 0 | 0 | ||
| Vinsol | (weight %/resin) | 10 | 10 | 0 | 0 | 0 | ||
| (1) carriage | Be full of cracks length | mm | 380 | 0 | 1750 | 3140 | 170 | |
| The generation ratio of be full of cracks | mm/1000cm 2 | 25 | 0 | 115 | 206 | 11 | ||
| Elephant skin | The |
1～2 |
1～2 grade | 3～4 |
4 |
4 grades | ||
| (2) framework | Be full of | mm | 0 | 50 | ||||
| The generation ratio of be full of cracks | mm/ |
0 | 7 | |||||
| Elephant skin | The |
1～2 |
1～2 grade | |||||
| (3) small-sized carriage | Be full of | mm | 0 | 340 | ||||
| Elephant skin | The |
1～2 |
1～2 grade | |||||
In the evaluation of large-scale steel casting, do not observe heat cracks in the steel casting that obtains in the comparative example 1.For comparative example 1 and example 2 in the past, confirm the generation of heat cracks in the steel casting, but its be full of cracks length is shorter, but the adaptability deterioration.Relative with it, comparative example 2 and the very long heat cracks of large-scale steel casting generation length of in the past making in the example 1.
In addition, about the generation state of the elephant skin in the large-scale steel casting, the situation of comparative example 2 is JIS3～4 grade shown in the photo copy of the steel casting among Fig. 6 (b).In addition, among Fig. 6, the part that presents white on the surface of large-scale steel casting is represented elephant skin.In addition, the generation state of the elephant skin in the example 1 and 2 is the JIS4 level in the past.Liquation was cooled off rapidly by core and the mobile decline of liquation when the reason that they form was considered to liquation injection casting mold.Relative with it, embodiment 2 and 4 is shown in the photo copy of the steel casting among Fig. 6 (a), and the generation state of elephant skin is JIS1～2 grade.
Here, if the length of the elephant skin that take place in the large-scale steel casting of comparing embodiment 4 and comparative example 2, as shown in Figure 7, the length of elephant skin significantly reduces among the embodiment 4, can confirm that the generation of elephant skin is inhibited effectively.As can be known from the above results, if adopt the present invention, can obtain significantly that heat cracks prevents effect and for the inhibition effect of liquation.
In addition, by the evaluation result of medium-sized and small-sized steel casting as can be known, among the embodiment 2 heat cracks does not take place, and the generation of elephant skin is inhibited effectively.Relative with it, confirm steel casting generation heat cracks in the comparative example 2.In addition, as a reference, the position that heat cracks takes place on the steel casting in the comparative example 2 is shown in Fig. 4 and Fig. 5 respectively.By this result also as can be known, can obtain special effect by the present invention.
The possibility of utilizing on the industry
The present invention can be effectively be used for using RCS to form casting mold by shell mould method and with the situation of this casting mold cast steel foundry goods, the situation of particularly casting the steel casting of thin-walled.
Claims (9)
1. a cast steel coated sand is characterized in that, comprises casting mold sand, with respect to this casting mold sand be 2.5～5.0 weight % phenolic resins, potassium nitrate and vinsol.
2. cast steel coated sand as claimed in claim 1 is characterized in that, the phenol composition of described phenolic resins comprises at least a kind of derivative of the residue that generates in the purifying that is selected from bisphenol-A, this bisphenol-A and the separated component in this residue.
3. cast steel coated sand as claimed in claim 1 or 2 is characterized in that, the incorporation of described potassium nitrate is 2～50 weight % with respect to described phenolic resins.
4. cast steel coated sand as claimed in claim 3 is characterized in that, the incorporation of described vinsol is 4～20 weight % with respect to described phenolic resins.
5. cast steel casting mold, it is thick 6～15mm, have 1000cm
2The casting mold of the steel casting of above surface area is characterized in that, uses each the described resin coating sand molding in the claim 1～4 to form.
6. cast steel casting mold as claimed in claim 5 is characterized in that, the calorific intensity of described casting mold is 120～175N/cm
2
7. a steel casting is characterized in that, the steel casting that it is to use claim 5 or 6 described cast steels to cast with casting mold, and the thickness of this steel casting is 6～15mm, has 1000cm
2Above surface area, the heat cracks that the foundry goods face that contacts with described casting mold takes place is below 70mm.
8. steel casting as claimed in claim 7 is characterized in that, be classified as 1～2 grade based on JISG 0588 of the elephant skin of described steel casting.
9. as claim 7 or 8 described steel castings, it is characterized in that the weight of described steel casting is more than 35kg.
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| JP2005206838 | 2005-07-15 | ||
| JP206838/2005 | 2005-07-15 | ||
| PCT/JP2006/314046 WO2007010848A1 (en) | 2005-07-15 | 2006-07-14 | Resin-coated sand for use in cast steel, casting mold made of the sand, steel casting casted using the casting mold |
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| CN101222992B CN101222992B (en) | 2010-05-26 |
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| CN102448637A (en) * | 2009-07-23 | 2012-05-09 | 旭有机材工业株式会社 | Phenol resin composition for shell molding, resin-coated sand for shell molding, and shell molding die obtained using the same |
| CN101823119A (en) * | 2010-06-04 | 2010-09-08 | 华中科技大学 | Coated sand for selective laser sintering (SLS) and preparation method thereof |
| CN103586399A (en) * | 2013-10-16 | 2014-02-19 | 昌利锻造有限公司 | Molding sand capable of quick air permeation and heat dissipation and preparation method thereof |
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| CN110267752A (en) * | 2017-02-10 | 2019-09-20 | 旭有机材株式会社 | The manufacturing method of mould material composition and the casting mold using it |
| CN110267752B (en) * | 2017-02-10 | 2022-01-11 | 旭有机材株式会社 | Mold material composition and method for producing mold using same |
| CN107252872A (en) * | 2017-05-18 | 2017-10-17 | 西峡县众德汽车部件有限公司 | One kind heating precoated sand and preparation method thereof |
| CN107214302A (en) * | 2017-05-18 | 2017-09-29 | 西峡县众德汽车部件有限公司 | A kind of new casting pouring method |
| CN108971416A (en) * | 2018-09-03 | 2018-12-11 | 王韶华 | A kind of casting High-temperature-reseasyng easyng collapse precoated sand |
| CN112355231A (en) * | 2020-11-11 | 2021-02-12 | 南阳仁创再生资源有限公司 | Water glass precoated sand for casting and preparation method thereof |
| CN112355231B (en) * | 2020-11-11 | 2022-03-29 | 南阳仁创再生资源有限公司 | Water glass precoated sand for casting and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4545192B2 (en) | 2010-09-15 |
| CN101222992B (en) | 2010-05-26 |
| WO2007010848A1 (en) | 2007-01-25 |
| JPWO2007010848A1 (en) | 2009-01-29 |
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