EP3006136A1 - Utilisation d'une composition basique en tant que moyen d'infiltration pour la matiere a mouler d'un moule destine a eviter des depots blancs (surfaces piquees) sur des elements en coulee, procede correspondant, moules et kits - Google Patents

Utilisation d'une composition basique en tant que moyen d'infiltration pour la matiere a mouler d'un moule destine a eviter des depots blancs (surfaces piquees) sur des elements en coulee, procede correspondant, moules et kits Download PDF

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Publication number
EP3006136A1
EP3006136A1 EP15189193.4A EP15189193A EP3006136A1 EP 3006136 A1 EP3006136 A1 EP 3006136A1 EP 15189193 A EP15189193 A EP 15189193A EP 3006136 A1 EP3006136 A1 EP 3006136A1
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EP
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Prior art keywords
mold
casting
acid
composition
water
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EP15189193.4A
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German (de)
English (en)
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Claus Joachim
Klaus Seeger
Christian Fourberg
Oliver Buchmann
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Huettenes Albertus Chemische Werke GmbH
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Huettenes Albertus Chemische Werke GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • 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
    • B22C1/18—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 inorganic agents
    • B22C1/181—Cements, oxides or clays

Definitions

  • the present invention relates to a use of a basic composition as an infiltrant for the molding material of a casting mold comprising quartz sand and an acid-cured binder, and to a process for producing a GJS or GJL casting.
  • the present invention also relates to corresponding molds and kits.
  • the melt liquefied materials, ferrous metals or non-ferrous metals are converted into shaped objects with specific workpiece properties.
  • the casting molds are divided into lost molds that are destroyed after each casting, and permanent molds, with each of which a large number of castings can be produced.
  • the lost forms usually consist of a refractory, granular molding material, which is solidified with the aid of a hardenable binder.
  • Shapes are negatives, they contain the emptying cavity, which results in the casting to be produced.
  • the inner contours of the future casting are formed by cores. In the manufacture of the mold, the cavity is shaped into the molding material by means of a model of the casting to be manufactured. Inner contours are represented by cores formed in a separate core box.
  • both organic and inorganic binders can be used, the curing of which can be effected by cold or hot processes.
  • Cold processes are processes in which the curing takes place essentially at room temperature without heating the molding material mixture.
  • the curing is usually carried out by a chemical reaction, which can be triggered, for example, by passing a gaseous catalyst through the molding material mixture to be cured, or by adding a liquid catalyst to the molding material mixture.
  • hot processes the molding material mixture is heated to a sufficiently high temperature after molding to drive off, for example, the solvent contained in the binder, or to initiate a chemical reaction by which the binder is cured by crosslinking.
  • the production of the casting molds can be carried out in such a way that the molding material is first mixed with the binder, so that the grains of the refractory molding material are coated with a thin film of the binder.
  • the molding material mixture obtained from molding material and binder can then be introduced into a corresponding mold and optionally compacted in order to achieve a sufficient stability of the casting mold.
  • the mold is cured, for example by heating it or by adding a catalyst which effects a curing reaction. If the mold has reached at least a certain initial strength, it can be removed from the mold.
  • molds for the production of metal bodies are often composed of so-called cores and molds. Different requirements are placed on the cores and molds. In molds, a relatively large surface area is available to dissipate gases that form during casting by the action of the hot metal. In cores usually only a very small area is available, through which the gases can be derived. If there is too much gas, there is a risk that gas will pass from the core into the liquid metal and lead to the formation of casting defects.
  • the internal cavities are therefore imaged by cores which have been solidified by cold box binders, ie a polyurethane-based binder, while the outer contour of the casting is represented by less expensive molds, such as a green sand mold, a mold bound by a furan resin or a phenol resin, or a steel mold.
  • cold box binders ie a polyurethane-based binder
  • organic polymers are mostly used as binders for the refractory, granular molding material.
  • granular molding material often washed, classified quartz sand is used, but also other molding materials such. Zirconsande, Chromitsande, chamois, olivine sands, feldspat ambience sands and Andalusitsande.
  • the molding material mixture obtained from mold base and binder is preferably present in a free-flowing form.
  • organic binders such as polyurethane, furan resin or epoxy-acrylate used in which the curing of the binder by addition of a catalyst.
  • binder depends on the shape and size of the casting to be produced, the conditions of production and the material used for the casting. For example, in the production of small castings that are produced in large numbers, polyurethane binders are often used because they allow fast cycle times and thus also a series production.
  • Processes in which the curing of the molding material mixture by heat or by subsequent addition of a catalyst have the advantage that the processing of the molding material mixture is not subject to any special time restrictions.
  • the molding material mixture can first be produced in larger quantities, which are then processed within a longer period of time, usually several hours.
  • the curing of the molding material mixture takes place only after molding, with a rapid reaction is sought.
  • the mold can be removed immediately after curing from the mold so that short cycle times can be realized. However, in order to obtain a good strength of the mold, the curing of the molding material mixture must be uniform within the mold. If the curing of the molding material mixture by subsequent addition of a catalyst, the mold is gassed after molding with the catalyst. For this purpose, the gaseous catalyst is passed through the casting mold.
  • the molding material mixture cures directly after contact with the catalyst and can therefore be removed very quickly from the mold.
  • the gassing times are prolonged, but can still arise sections in the mold, which are achieved very poorly or not at all by the gaseous catalyst.
  • the amount of catalyst therefore increases sharply with increasing size of the mold.
  • the weight of the cores is often about 1000 kg or more.
  • methods in which the hardening with gas or by heat such large cores are difficult or impossible to produce from a technical point of view.
  • cold-curing methods are used.
  • no-bake binder In the production of molds for large castings, such as engine blocks of marine diesel engines or large machine parts, such as hubs of rotors for wind power plants, so-called “no-bake binder” are used for the reasons mentioned mostly.
  • the refractory base material for example sand
  • a catalyst hardener
  • the binder is added and distributed evenly on the already catalyst-coated grains of the refractory base molding material by mixing.
  • continuous flow mixers In this process is often worked with so-called continuous flow mixers.
  • the resulting molding material mixture can then be shaped into a shaped body. Since binder and catalyst are evenly distributed in the molding material mixture, the curing is largely uniform even with large moldings.
  • the refractory base molding material eg sand
  • the hardener can be added.
  • it may, especially in the production of molds for large castings, come because of a partial, local too high concentration of the curing agent to partial hardening or crosslinking of the binder, whereby an inhomogeneous molding material would be obtained.
  • the reaction rate can be influenced for a given amount of the binder and the refractory base molding material, for example, by the type and amount of the catalyst or by the addition of retarding components.
  • the processing of the molding material mixture should be carried out under very controlled conditions, since the rate of curing is influenced for example by the temperature of the molding material mixture.
  • the "classic" no-bake binders are often based on furan resins and phenolic resins. They are often offered as systems (kits) wherein one component comprises a reactive furan resin and the other component comprises an acid, which acid acts as a catalyst for the curing of the reactive resin component.
  • Furan and phenolic resins show very good disintegration properties during casting. Under the action of heat of the liquid metal, the furan or phenolic resin decomposes and the strength of the mold is lost. After casting, therefore, cores, possibly after prior shaking of the casting, pour out very well from cavities.
  • Furfuryl alcohol contains reactive furan resins, which regularly comprise furfuryl alcohol as an essential component. Furfuryl alcohol can react with itself under acid catalysis and form a homopolymer. Furfuryl alcohol is generally not used alone for the preparation of furan no-bake binders, but further compounds are added to the furfuryl alcohol which are copolymerized into the resin. Examples of such compounds are aldehydes, such as formaldehyde or furfural, ketones, such as acetone, phenols, urea or polyols, such as sugar alcohols or ethylene glycol. The resins may be added with other components that affect the properties of the resin, such as its elasticity. Melamine can be added, for example, to bind still free formaldehyde.
  • Furan no-bake binders are most often prepared by first producing precondensates of, for example, urea, formaldehyde, and furfuryl alcohol under acidic conditions. These precondensates are then diluted with furfuryl alcohol. Likewise, urea and formaldehyde can be reacted alone. This produces so-called UF resins ("urea formaldehyde” resins, "aminoplasts"). These are usually subsequently diluted with furfuryl alcohol.
  • Advantages of this manufacturing method are a higher flexibility / variability in the product range and lower costs, because it is cold mixing processes. The disadvantage is often that certain chemical and performance properties can not be achieved. Furthermore, UF resins are often cloudy, so that usually made therefrom binder are also cloudy and inhomogeneous.
  • Resoles can also be used to prepare furan no-bake binders. Resoles are prepared by polymerization of mixtures of phenol and formaldehyde. These resoles are then often diluted with a large amount of furfuryl alcohol.
  • Furan no-bake binders are regularly cured with an acid. This acid catalyzes the crosslinking of the reactive furan resin. It should be noted that, depending on the type of binder, certain amounts of acid should not be exceeded, since alkaline components, which may be present in the refractory base molding material, can partially neutralize the acid.
  • acids are sulfonic acids, phosphoric acid or sulfuric acid. In some specific cases, combinations of these are used, inter alia, in combination with other carboxylic acids. Further, certain "curing moderators" can be added to the furan no-bake binder.
  • Phosphoric acid is often used as an acid catalyst for curing in concentrated form, ie at concentrations greater than 70%. However, it is (with some exceptions) only for the catalytic curing of furan resins with a relatively high proportion of urea, since essentially the curing of the aminoplast content in the furan no-bake binder responds. The nitrogen content of such resins is usually more than 2.0% by weight. Sulfuric acid, as a relatively strong acid, can be added as a starter for the curing of furan resins to weaker acids. During casting, however, a smell typical of sulfur compounds develops. In addition, there is a risk that the casting material sulfur is absorbed, which affects its properties.
  • the selection of the acid catalyst for curing has a significant influence on the curing behavior of the binder, the properties of the molding material mixture and the casting mold or the core obtainable therefrom.
  • the rate of curing can be influenced by the amount and the strength of the acid.
  • High amounts of acid or stronger acids lead to an increase in the curing rate.
  • the processing time of the molding material mixture is shortened too much, so that the workability is greatly impaired or even processing is no longer possible.
  • the binder such as a furan resin
  • the binder also become brittle upon curing, which adversely affects the strength of the mold.
  • too small amounts of acid catalyst the resin is not completely cured (or the curing takes a long time), resulting in lower strength of the mold.
  • New foundry sand is often used in the manufacture of foundry molds, while frequently recycled mold base stock (e.g., sand) is used for the molds.
  • Refractory mold raw materials which have been solidified with furan no-bake binders, can be worked up very well again. The workup is carried out either mechanically by mechanically rubbing off a shell formed from residual binder or by thermally treating the used sand. With mechanical workup or with combined mechanical / thermal processes, return rates of up to almost 100% can be achieved.
  • Phenolic resins the second large group of acid-catalyzed curable no-bake binders, contain resoles as reactive resin components, ie phenolic resins prepared with a molar excess of formaldehyde. Phenolic resins show lower reactivity compared to furan resins and require strong sulfonic acids as catalysts. Phenolic resins show a relatively high viscosity, which increases even more with prolonged storage of the resin.
  • the molding compound After the phenol no-bake binder has been applied to the refractory base molding material, the molding compound should be processed as promptly as possible so as not to suffer deterioration in the quality of the molding compound due to premature curing, resulting in deterioration of the strength of the molding compound mixture produced molds can lead.
  • the flowability of the molding material mixture is usually worse than a comparatively produced molding material with a furan no-bake binder. In the production of the mold, the Molding material mixture are therefore carefully compacted in order to achieve a high strength of the mold can.
  • the preparation and processing of such a molding material mixture should take place at temperatures in the range of 15 to 35 ° C. If the temperature is too low, the molding material mixture can be processed worse because of the high viscosity of the phenol no-bake resin. At temperatures of more than 35 ° C, the processing time is shortened by premature curing of the binder.
  • molding mixtures based on phenol no-bake binders can also be worked up again, in which case mechanical or thermal or combined mechanical / thermal processes can also be used.
  • the acid used as catalyst in the case of furan or phenol no-bake processes has a very great influence on the properties of the casting mold.
  • the acid must have sufficient strength to ensure a sufficient rate of reaction in the curing of the mold.
  • the curing should be well controllable, so that also sufficiently long processing times can be set. This is particularly important in the production of molds for very large castings, the construction requires a longer period.
  • the acid must not accumulate in the regenerate in the regeneration of scrap materials (i.e., mold materials already used to make lost molds or cores, such as old sands). If acid is introduced into the molding material mixture via the regenerate, this shortens the processing time and leads to a deterioration in the strength of the casting mold produced from the regenerate.
  • scrap materials i.e., mold materials already used to make lost molds or cores, such as old sands.
  • Phosphoric acid is, as already explained, only for the curing of certain furan resin qualities.
  • phosphoric acid is not suitable for the curing of phenolic resins.
  • phosphoric acid shows a tendency to regenerate which makes reuse of the regrind difficult. Sulfuric acid during casting and during thermal regeneration leads to the emission of sulfur dioxide, which has corrosive properties, is harmful to health and represents an odor nuisance.
  • Spheroidal graphite cast iron is an iron-carbon material whose carbon content is predominantly in globular (globular) form. Cast iron with nodular graphite has steel-like material properties. Due to the globular shape of the graphite, high strengths result with very good, permanent deformation (elongation). Low perlite content increases both machinability and associated tool life. Ductile iron is used, for example, in the automotive industry, mechanical engineering and shipbuilding, in pressure vessels or in wind power. GJS cast iron grades are described in DIN EN 1563, Foundry - nodular cast iron.
  • Cast iron with lamellar graphite also has excellent practical properties and in many cases presents similar requirements to those skilled in the art as GJS.
  • GJS lamellar graphite
  • the lining consists essentially of (fibrous) silicon oxides. When the castings are blasted, the coating is removed, leaving only the pitted surface.
  • the defect occurs in GJS and GJL castings produced by casting molds and cores made of chemically bonded molding material, which in turn consists of quartz sand and an acid-cured binder. Especially in acid-cured furan resin molds and other acid-cured, cold-curing processes, such as the phenolic resin process, the error occurs. The most common error rate was found in regenerated furan resin sands with an ignition loss between 3 and 4.5%.
  • the error also occurs in the use of cores and molds made by the croning process as well as in the clay-bonded molding process.
  • the white deposits mainly occur in thick-walled parts, ie on medium to heavy castings. Even smaller compact castings with a large module are affected. On the casting, the error mostly occurs in thermally highly stressed zones, such as the radii, but can also be drawn from there over larger areas. Below the surface of the affected zones, the graphite is partially degenerate.
  • the casting defect leads to increased reworking in the foundry and so far can only be counteracted by an increased oversize of the affected areas. In extreme cases, scarred surfaces lead to rejects of the casting.
  • the affected areas must first be ground consuming before being subjected to ultrasonic testing or crack testing for quality control of the casting.
  • Manganese (IV) oxide manganesese dioxide
  • the use of impregnation coatings with manganese dioxide has the disadvantage that the manganese dioxide is the fire resistance
  • these penetrating sizing agents can at best reduce the casting defect of "scarred surfaces”.
  • penetration sizing is used, i. Finishes that penetrate into the molding material and fill the pores in the molding material with their refractory materials. They are particularly suitable for preventing casting defects such as penetration and erosion. These sizes usually contain larger amounts of refractories and may also contain inorganic or organic binders. Commercially available sizes penetrate regularly when applied to the molding material. An effect against scarred surfaces is not known. In our own experiments, for example, with the magnesite size 5848 of the company Wilsontenes-Albertus GmbH, Dusseldorf, containing basic refractories, no effect on the formation of pitted surfaces could be observed.
  • Formcoats which are applied to molding surfaces are also frequently used. These form varnishes are solutions of organic resins in a solvent. They serve to harden the mold surface. An activity against scarred surfaces can not be observed.
  • the document DE102008025311 A1 discloses an odor and pollutant coating composition for box-bonded cast metal.
  • WO 2009/004090 A1 discloses a method for casting a molten metal.
  • the publication DE 2407344 relates to a process for the production of foundry molds and cores.
  • an acid-cured binder is understood as meaning a crosslinked organic polymer which, after curing, has bound a substrate (quartz sand) and in water by the free and necessary acid added for crosslinking (curing) the organic polymer would produce a pH of ⁇ 7.0.
  • a casting mold is understood as meaning the entirety of outer mold parts and, if present, inner mold parts (for example cores).
  • a base or an acid is understood as meaning a Br ⁇ nsted base (proton acceptor) or acid (proton donor).
  • bases are compounds which form salts with acids by neutralization or form hydroxide ions in aqueous solutions.
  • sodium hydroxide is a base, since sodium hydroxide forms hydroxide ions in aqueous solutions.
  • the basic composition comprises as or in the carrier liquid for the basic component water and wherein the aqueous phase preferably has a pH of> 8, preferably a pH of> 10, particularly preferably a pH Value of> 12, particularly preferably has a pH of> 13.
  • a use according to the invention wherein the infiltrant for the molding material of a mold comprising quartz sand and an acid-cured binder is so infiltrated into the molding material, that an infiltrating product is formed, which at least to an infiltration depth of 2 mm on contact reacts basic with water, measured from the surface of the mold, preferably to at least an infiltration depth of 5 mm, more preferably 10 mm, most preferably at each infiltration depth in the range of 2 to 5 mm, the infiltration product reacts basicly on contact with water.
  • a use according to the invention as an infiltrant for the mold material of a casting mold cured by means of a no-bake binder and for suppressing the formation of pitted surfaces during the casting process, wherein the no-bake binder is cured by an acid catalyst for curing the reactive resin component of the no-bake binder, wherein the acidic catalyst comprises sulfonic acids, phosphoric acid, sulfuric acid, or combinations thereof.
  • one, more than one or all of the inorganic bases in the basic component is selected from the group consisting of alkali metal hydroxide, alkaline earth metal hydroxide and water glass, in particular sodium silicate, potassium silicate or lithium water glass.
  • alkali metal hydroxides in accordance with the invention are lithium hydroxide, sodium hydroxide and potassium hydroxide, in particular potassium hydroxide and sodium hydroxide.
  • Alkaline earth metal hydroxides preferred according to the invention are magnesium hydroxide, calcium hydroxide and strontium hydroxide, in particular calcium hydroxide and magnesium hydroxide.
  • compositions in which the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water and organic compounds having a boiling point below 100 ° C at 1000 hPa, that the carrier liquid after application of the composition at least parts of the mold evaporates faster than comparable compositions whose organic compounds have a boiling point above 100 ° C. at 1000 hPa. This makes it possible to shorten the waiting time between application of the composition to the casting mold and the subsequent filling of the casting cavity with a molten iron-carbon alloy.
  • the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water, methanol, ethanol, propanol, butanol, acetone and gasoline, preferably in the carrier liquid, the total amount of water, methanol, Ethanol, propanol, butanol, acetone and gasoline is more than 50 wt .-%, based on the total amount of the carrier liquid.
  • the composition comprises one or more surfactants.
  • the use of surfactants in the composition results in lowering the surface tension of the composition and in wetting the composition, wetting of the casting mold is improved.
  • the penetration (penetration) of the composition into the upper layers of the mold is improved.
  • the presence of one or more surfactants is preferred when only water is present as carrier liquids.
  • Suitable surfactants are anionic surfactants, nonionic surfactants, cationic surfactants and amphoteric surfactants.
  • the composition comprises one or more binders, wherein preferably the one or at least one of the plurality of binders is self-curing in the air and / or dries when the carrier liquid is removed.
  • the composition comprises one or more binders which are basic, in particular basic binders which are listed above, the basic binder or the basic binders fulfill the function of the basic component consisting of one or more bases.
  • the basic binder or the basic binders fulfill the function of the basic component consisting of one or more bases.
  • Other basic components which are not binders may be present in the composition, however, the presence of such other basic components is not mandatory.
  • Organic binders are understood to mean binders which are based on carbon and, apart from hydrogen, oxygen, sulfur and nitrogen, contain no further atoms. Organic binders may be present as salts; In such cases, in addition to a charged organic binder ion, charged counterions are present, which need not or not exclusively consist of the named elements.
  • solvent constituents and possible water of crystallization of the silicates are assigned not to the silicates but only to the total amount of the composition.
  • the composition contains one or more solids suspended in the carrier liquid, preferably one or more solids suspended in the carrier liquid which are inert upon contact with water or have an acidic or basic surface, wherein preferably one or more solids suspended in the carrier liquid are inorganic solids, wherein the inorganic solid is preferably not silicate.
  • the composition containing a proportion of solids suspended in the carrier liquid and having a particle size of less than 0.075 mm preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size less than 0.075 mm, preferably contains a proportion of solids suspended in the carrier liquid with a particle size of less than 0.075 mm in the range of> 50% by weight, based on the total amount of solids, preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solid.
  • composition contains one or more dyes, preferably contains one or more color pigments and / or dyes dissolved in the carrier liquid.
  • composition containing one or more dyes has the advantage that when the composition is applied to the mold or to parts of the mold it can be directly recognized on which areas of the mold the composition has already been applied.
  • brushing or spraying the composition when dipping the mold in the composition or when flooding the mold with the composition, it can be quickly appreciated whether all required areas of the mold are sufficiently in contact with the composition. Also can be seen after breaking the mold optically how deep the composition has penetrated into the molding material surface.
  • composition contains no graphite and no oxides of zirconium, silicon, aluminum, magnesium and calcium and no mixed oxides of these elements.
  • the mold material of a mold comprising quartz sand and an acid-cured binder, the mold (or at least portions of the mold cavity defining surfaces) preferably reacting acidically upon contact with water.
  • the quartz sand is a regenerated quartz sand, which was preferably prepared by working up a molding material mixture comprising quartz sand and an acid-cured binder.
  • step (ii) is carried out to form an infiltration product which is basic to at least an infiltration depth of 5 mm, more preferably 10 mm, upon contact with water, measured from the surface of the mold, most preferably at each infiltration depth in the range of 2 to 5 mm, the infiltration product reacts basicly upon contact with water.
  • one, more than one or all of the inorganic bases in the basic component is or are selected from the group consisting of alkali metal hydroxide, alkaline earth metal hydroxide and water glass, in particular sodium silicate, potassium silicate or lithium water glass.
  • the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water and organic compounds having a boiling point below 100 ° C at 1000 hPa, preferably in the carrier liquid, the total amount of water and organic compounds having a boiling point below 100 ° C at 1000 hPa more than 50 wt .-%, based on the total amount of the carrier liquid.
  • the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water, methanol, ethanol, propanol, butanol, acetone and Gasoline, wherein preferably in the carrier liquid, the total amount of water, methanol, ethanol, propanol, butanol, acetone and gasoline is more than 50 wt .-%, based on the total amount of the carrier liquid.
  • the basic composition preferably comprises one or more surfactants.
  • the basic composition preferably comprises organic binders in a concentration of from 0.2 to 40% by weight, based on the total amount of the composition, preferably from 0.2 to 10% by weight, more preferably from 0.2 to 5% by weight and or inorganic binders in a concentration of 0.5 to 80 wt .-%, based on the total amount of the composition.
  • the basic composition preferably comprises alkaline silicate in a concentration of 5 to 50 wt .-% based on the total amount of the composition, particularly preferably 10 to 40 wt .-%.
  • the basic composition preferably contains one or more solids suspended in the carrier liquid, preferably one or more solids suspended in the carrier liquid which are inert upon contact with water or have an acidic or basic surface, preferably one or more of which are present in the carrier liquid
  • Carrier liquid suspended solids are inorganic solids, wherein the inorganic solid is preferably not silicate.
  • the composition preferably contains a proportion of suspended in the carrier liquid solids having a particle size of less than 0.075 mm, preferably a proportion of suspended in the carrier liquid inorganic solids having a particle size less than 0.075 mm, preferably a proportion of suspended in the carrier liquid solids having a particle size smaller 0.075 mm in the range of> 50 wt .-%, based on the total amount of solids, preferably a proportion of suspended in the carrier liquid inorganic solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solid.
  • the basic composition preferably contains one or more dyes, preferably one or more color pigments and / or dyes dissolved in the carrier liquid and / or the composition contains no graphite and no oxides of zirconium, silicon, aluminum, magnesium and calcium and none Mixed oxides of these elements.
  • the method according to the invention in all its preferred aspects and embodiments, is equally suitable for the production of a GJS or GJL casting and for suppressing the formation of pitted surfaces on these castings.
  • the carrier liquid of the composition to be used according to the invention is at least substantially removed prior to filling the mold cavity with a molten iron-carbon alloy. This is usually done by evaporating (drying) the carrier liquid. The process can be accelerated by heat input or radiation input (microwave or infrared radiation). It is also possible to carry out the drying by flaming off combustible volatile carrier liquids such as alcohols.
  • a (for example commercial) size can be applied to the casting mold or to parts of the casting mold. Usually, first the composition and then the size is applied. If no sizing is provided, the dried composition reacted with ingredients from areas of the surface of the mold will contact the molten iron-carbon alloy. When the size is applied to the composition (or the dried composition or the infiltrated area), this size separates the molten iron-carbon alloy from the thus dried and reacted composition.
  • the composition penetrates the molding material at different depths depending on the application. Especially with larger molds or cores, as they are needed for the production of the vulnerable parts, there are always better and less dense areas into which the infiltrant will penetrate at different depths. Also, depending on the manufacturer, the quartz sands used differ considerably in grain size and shape. This also influences the penetration depth (infiltration depth). In our own experiments it has been shown that a deeper infiltration into the molding material surface causes a better error suppression.
  • the penetration depth can be determined in practice by penetrating a molding material surface in a suitable manner with the composition to be used according to the invention or, for comparison purposes, with another infiltrant and then breaking or scratching the molding material at a suitable location.
  • the penetration depth can be determined from the discoloration of the sand bodies, e.g. be recognized by the carrier liquid of the infiltrant. For more accurate determination, e.g. To determine the number of penetrated sand layers, a magnifying glass or an optical microscope and a corresponding scale can be used. Alternatively or additionally, the number of discolored sand layers can be determined (see below for method).
  • the determination of the depth of penetration of the infiltrant may also be performed on well-compacted specimens.
  • Test specimens are produced for this purpose as described in the VDG leaflet P72, Binder Testing, available from the VDG Information Center, PO Box 105144, D-400042 Düsseldorf. Notwithstanding the requirement P72, however, the test specimens are compacted by means of 5 driving strokes analogous to the VDG leaflet P73 with a pile driver from Simpson Technologies GmbH, Sennweidstrasse 43, CH 6312 Steinhausen. The depth of penetration is determined on the best-compacted side of a test piece produced in this way.
  • the quartz sand is a regenerated quartz sand, which was preferably prepared by working up a molding material mixture comprising quartz sand and an acid-cured binder.
  • the process allows and promotes the use of recycled / regenerated sand and reduces the casting error commonly associated with such use.
  • a casting mold according to the invention is produced on a regular basis by means of a process according to the invention and / or under the use according to the invention of a basic composition as infiltrant; to that extent all above and below as well as in the claims as preferred specified embodiments relating to the inventive method or the inventive use also apply to the mold according to the invention, and vice versa.
  • a casting mold according to the invention is a mold made of a chemically bound molding base material, the surfaces of which define a mold cavity, for producing a GJS or GJL casting, wherein the chemically bonded molding base comprises one or more acid-cured binders and quartz sand, wherein at least one region of the mold defining the mold cavity comprises an infiltration product which is basic to at least an infiltration depth of 2 mm upon contact with water, measured from the surface of the mold.
  • Such a mold according to the invention surprisingly contributes to suppressing the formation of pitted surfaces on castings (in particular GJS and GJL).
  • the chemically bonded molding base comprises one or more acid-cured no-bake binder and quartz sand, wherein the no-bake binder comprises furan resins and / or phenolic resins.
  • a mold according to the invention wherein from the mold cavity defining surface more than 15 mm remote lying, preferably more than 25 mm away areas of the mold, measured from the surface of the mold, react acid on contact with water.
  • the process according to the invention is preferably carried out such that in step (ii) such a casting mold results; this is then used in subsequent steps.
  • a mold according to the invention wherein in the mold cavity, a liquid or solidified iron-carbon alloy is arranged, selected from the group consisting of iron-carbon alloys for the formation of GJS and GJL castings.
  • a casting mold according to the invention wherein the chemically bound molding base material is a regenerated quartz sand, which was preferably prepared by working up a molding material mixture.
  • kits according to the invention are regularly employed in a method according to the invention and / or in connection with the use according to the invention of a basic composition as infiltrant.
  • a kit according to the invention is regularly used for producing a casting mold according to the invention; to that extent all above and below as well as in the claims as preferred specified embodiments relating to the inventive method, the inventive use or the inventive mold also apply to the kit according to the invention, and vice versa.
  • kits wherein one, more than one or all of the bases have a pK B value in water at 25 ° C of less than 3.0, preferably less than 1.0.
  • kits according to the invention wherein one, more than one or all of the inorganic bases in the basic component is or are selected from the group consisting of alkali metal hydroxide, alkaline earth metal hydroxide and water glass, in particular sodium silicate, potassium silicate or lithium water glass.
  • the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water and organic compounds having a boiling point below 100 ° C. at 1000 hPa,
  • the total amount of water and organic compounds having a boiling point below 100 ° C at 1000 hPa is more than 50 wt .-%, based on the total amount of the carrier liquid.
  • the carrier liquid for the basic component comprises one or more compounds selected from the group consisting of water, methanol, ethanol, propanol, butanol, acetone and gasoline,
  • the total amount of water, methanol, ethanol, propanol, butanol, acetone and gasoline is more than 50 wt .-%, based on the total amount of the carrier liquid.
  • kits according to the invention wherein the basic composition additionally comprises one or more surfactants.
  • kit according to the invention where the basic composition comprises one or more binders,
  • kits according to the invention wherein the composition contains one or more solids suspended in the carrier liquid, preferably one or more solids suspended in the carrier liquid which are inert upon contact with water or have an acidic or basic surface, wherein preferably one or more solids suspended in the carrier liquid are inorganic solids, wherein the inorganic solid is preferably not silicate.
  • a kit according to the invention is preferred, wherein the composition contains a proportion of solids suspended in the carrier liquid with a particle size of less than 0.075 mm, preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size less than 0.075 mm, preferably contains a proportion of solids suspended in the carrier liquid with a particle size of less than 0.075 mm in the range of> 50% by weight, based on the total amount of solids, preferably contains a proportion of suspended in the carrier liquid inorganic solids having a particle size of less than 0.075 mm in the range of> 50 wt .-%, based on the total amount of solid.
  • kits according to the invention are also preferred, wherein the composition contains one or more dyes, preferably contains one or more color pigments and / or dyes dissolved in the carrier liquid and or wherein the composition contains no graphite and no oxides of zirconium, silicon, aluminum, magnesium and calcium and no mixed oxides of these elements.
  • the specimens were penetrated per m 2 area with the same amount of infiltrant as described in the field trials.
  • the determination of the penetration depth of the infiltrant into the test specimens was carried out analogously to practice.
  • the specimens were broken immediately after the order and the penetration depth was determined by light microscopy with appropriate magnification by means of a scale or by counting the penetrated sand layers.
  • the infiltration is to be recognized by a darker discoloration of the grains of sand by the carrier liquid, or after drying, for example, by a discoloration by a color body.
  • the number of penetrated sand layers is determined as follows: The test specimen is penetrated by means of the desired method with the infiltrant. Then it is broken in the transverse direction. Starting from the center of the molding surface, the number of grains of sand from the molding surface is counted perpendicular to the test center. It counts the grains of sand, which are discolored by the carrier liquid and / or a color body. A grain of sand that is adjacent to the first grain of sand and overlaps less than half of its own diameter is counted as a new layer of sand. The grains of sand must also be wetted to at least half. The determination is repeated at least 5 times on the best compressed side of the test specimen. Thus, for example, with a sand having a mean grain size of 0.36 mm, a penetration depth of about 2.7 mm results for 10 penetrated sand layers.
  • Sieve analysis according to DIN 3310 as follows: sieve fraction proportion of cumulatively Sieve analysis> 1,000 mm % 0.06 0.06 Sieve analysis> 0.710 mm % 0.27 0.33 Sieve analysis> 0.500 mm % 3.71 4.04 Sieve analysis> 0.355 mm % 22.50 26.54 Sieve analysis> 0.250 mm % 43.61 70.15 Sieve analysis> 0.180 mm % 23,03 93.18 Sieve analysis> 0.125 mm % 6.04 99.22 Sieve analysis> 0.090 mm % 0.47 99.69 Sieve analysis> 0.063 mm % 0.16 99.85 Sieve analysis ⁇ 0.063 mm % 0.14 99.99 •
  • the ignition loss according to VDG leaflet P33 is as follows: 4.7% • The residual acid [mg NaOH / 100] according to HA test specification QS no.
  • Figure 5 shows an example of a form used for the trial casts 1-3.
  • Table 1 Composition of infiltrants / test substances in test casting 1: Field in shape and casting 4 2 substance Infiltrant A, (Inventive) / Proportion [% by Weight] reference comment water 17.1 ethanol 17.1 Refractory products 52.3 95% finer than 0.063 mm, determined with air jet sieve color pigment 0.8 99% finer than 0.032 mm, determined with the air jet sieve Rheological additives, modifiers, thickeners, additives 4.0 resin 6.0 KOH 2.7 NaOH
  • Results of test casting 1 Table 2: Evaluation of the results of test casting 1: infiltrant field Evaluation of the faulty image "scarred surface" comment A 4 No pores or scars best result reference 2 Pores and scars in the radius and some pores on the surface
  • Figures 6 and 7 show photographs of fields 4 and 2 from trial casting 1.
  • Table 3 Composition of the infiltrants / test substances in test casting 2: Field in shape and casting 1 2 3 5 substance Infiltrant A, (Inventive) / Proportion [% by Weight] Infiltrant B / portion (according to the invention) [% by weight] reference Commercially available magnesite size from HA, magnesite size 5848, not according to the invention [% by weight] comment water 17.1 8.9 - ethanol 17.1 26.2 23 (different alcohols) Refractory products 52.3 58 71 95% finer than 0.063 mm, determined with the air jet sieve color pigment 0.8 0.9 0.1 99% finer than 0.032 mm, determined with the air jet sieve Rheological additives, modifiers, thickeners, additives 4.0 5.1 resin 6.0 0.4 0.8 KOH 2.7 3.0 - NaOH 0.3 -
  • Penetration depth of the infiltrant A in the molding material depending on the compression of the molding material of the form: 1.7-2.4 mm
  • Table 4 Evaluation of the results of test casting 2: infiltrant field Evaluation of the faulty image "scarred surface" comment A 1 No pores or white adhesions best result B 2 No pores or white adhesions Good result reference 3 Pores and scars in the radius and on the surface Bad result Magnesite size 5848 5 Pores and scars in the radius and on the surface Bad result Figure 8 shows a photograph of the manufactured casting with fields 1 to 5.
  • Table 5 Composition of the infiltrants / test substances in test casting 3: Field in shape and casting 1 4 5 substance Infiltrant A (Inventive) / Percentage [% by Weight] Infiltrant D (Inventive) / Percentage [% by Weight] reference comment water 17.1 25.7 ethanol 17.1 - Refractory products 52.3 61.7 95% finer than 0.063 mm, determined with the air jet sieve color pigment 0.8 - 99% finer than 0.032 mm, determined with the air jet sieve Rheological additives, modifiers, thickeners, additives 4.0 3.85 wetting agent 0.05 resin 6.0 6.0 KOH 2.7 2.7 Table 6: Composition of the infiltrants / test substances in test casting 3: Field in shape and casting 3 6 7 8th substance Infiltrant E (Inventive) / Proportion [% by Weight] Infiltrant F (Inventive) / Proportion [% by Weight] Infiltrant G (Inventive) / Proportion [% by Weight] Infiltration agent
  • Figure 9 shows a photograph of the manufactured casting with the corresponding casting surfaces.
  • Figure 10 shows a photograph of the manufactured casting with the corresponding cast surfaces 1 to 4.
  • Part of the mold surface in the top box was treated with the infiltrant A (see above). 1170 g / m 2 molding surface was applied.
  • Figure 11 shows the photograph of the casting produced in Example 3.
  • the left surface of the casting was represented by the area of the forming surface in the top box treated with the infiltrant A.
  • Example 3 analogous examples were carried out for GJL castings. Also in this regard, it was found that the formation of pores and scars was surprisingly greatly reduced by infiltrating the molding material with a basic composition to be used according to the invention.
  • Figures 13 and 14 are detail shots of GJL castings with a respective unit weight of 2,016 kg; the particular casting material was "GG20" (that is, an alloy for making a GJL casting).
  • the casting temperature was identical in both cases and was about 1300 ° C.
  • Figure 13 relates to a comparative example in which no infiltration of the molding material of the mold took place. Otherwise, in the comparative example, only steps were carried out which correspond to the procedure according to the invention.
  • Figure 14 relates to an example according to the invention in which the casting mold was infiltrated with a basic composition so that, up to an infiltration depth of about 6 mm, the resulting infiltration product reacted basicly upon contact with water, measured from the surface of the casting mold. Otherwise, the procedure in Comparative Example and Example was identical.
  • the infiltrant used in the example according to the invention was a basic composition according to Example 3 above.
  • Figure 13 shows at the lower edge of the image a surface area with an approximately triangular shape, which has a pronounced pitted surface.
  • Figure 14 (Concerning the casting produced in accordance with the invention) shows in the corresponding area of the casting a particularly smooth surface structure, which has no disturbing scars or pores.
  • the casting produced according to the invention according to Figure 14 was produced using a mold whose surface was treated only in some areas with the inventive composition according to Example 3.
  • the treated area was in the mold exactly where, in the comparative example, the triangular area with a scarred surface was adjacent the casting.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
EP15189193.4A 2014-10-10 2015-10-09 Utilisation d'une composition basique en tant que moyen d'infiltration pour la matiere a mouler d'un moule destine a eviter des depots blancs (surfaces piquees) sur des elements en coulee, procede correspondant, moules et kits Pending EP3006136A1 (fr)

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DE102014220632.4A DE102014220632A1 (de) 2014-10-10 2014-10-10 Verwendung einer basischen Zusammensetzung als Infiltrationsmittel für den Formstoff einer Gießform zur Vermeidung von weißen Belägen

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CN109641261A (zh) * 2016-06-30 2019-04-16 胡坦斯·阿尔伯图斯化学厂有限公司 在用于铁铸造和钢铸造的非永久性模具或型芯上用于制造模具涂层的铸型涂料组分
CN111266521A (zh) * 2018-12-05 2020-06-12 洛阳鹏起实业有限公司 一种铸造用复合砂芯及其制备方法

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CN107649642A (zh) * 2017-10-27 2018-02-02 湖州正德轻工机械有限公司 一种低成本型砂
CN108705026B (zh) * 2018-06-22 2020-07-14 佛山市高明利钢精密铸造有限公司 一种形状复杂不锈钢制件铸造专用型砂的制备方法

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JPS57171540A (en) 1981-04-17 1982-10-22 Mitsubishi Heavy Ind Ltd Preventing method for sulfurization of cast steel casting
WO2009004090A1 (fr) 2007-07-05 2009-01-08 Fritz Winter Eisengiesserei Gmbh & Co. Kg Procédé de coulée de métal en fusion
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JPS57171540A (en) 1981-04-17 1982-10-22 Mitsubishi Heavy Ind Ltd Preventing method for sulfurization of cast steel casting
WO2009004090A1 (fr) 2007-07-05 2009-01-08 Fritz Winter Eisengiesserei Gmbh & Co. Kg Procédé de coulée de métal en fusion
DE102008025311A1 (de) 2008-05-27 2009-12-03 Ashland-Südchemie-Kernfest GmbH Geruchs- und schadstoffadsorbierende Beschichtungsmasse für den kastengebundenen Metallguss

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Cited By (3)

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Publication number Priority date Publication date Assignee Title
CN109641261A (zh) * 2016-06-30 2019-04-16 胡坦斯·阿尔伯图斯化学厂有限公司 在用于铁铸造和钢铸造的非永久性模具或型芯上用于制造模具涂层的铸型涂料组分
US11027328B2 (en) 2016-06-30 2021-06-08 HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung Refractory coating composition for making facings on temporary molds or on cores for iron and steel casting operations
CN111266521A (zh) * 2018-12-05 2020-06-12 洛阳鹏起实业有限公司 一种铸造用复合砂芯及其制备方法

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