EP0078408B1 - Verfahren zur Herstellung von Giessformen für Metallguss - Google Patents

Verfahren zur Herstellung von Giessformen für Metallguss Download PDF

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Publication number
EP0078408B1
EP0078408B1 EP82109138A EP82109138A EP0078408B1 EP 0078408 B1 EP0078408 B1 EP 0078408B1 EP 82109138 A EP82109138 A EP 82109138A EP 82109138 A EP82109138 A EP 82109138A EP 0078408 B1 EP0078408 B1 EP 0078408B1
Authority
EP
European Patent Office
Prior art keywords
sanding
slip
binder
metal casting
refractory
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP82109138A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0078408A2 (de
EP0078408A3 (en
Inventor
Friedhelm Schnippering
Karl-Martin Dr. Rödder
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Huels Troisdorf AG
Dynamit Nobel AG
Original Assignee
Huels Troisdorf AG
Dynamit Nobel AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huels Troisdorf AG, Dynamit Nobel AG filed Critical Huels Troisdorf AG
Publication of EP0078408A2 publication Critical patent/EP0078408A2/de
Publication of EP0078408A3 publication Critical patent/EP0078408A3/de
Application granted granted Critical
Publication of EP0078408B1 publication Critical patent/EP0078408B1/de
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes

Definitions

  • the present invention relates to a process for producing casting molds for metal casting with the aid of binders based on silicic acid esters and refractory substances. Binding agents and refractory materials form a flowable slip that is applied to the model and then sanded. Hardening is carried out using a hardener (DE-A-2349593).
  • DE-A-2349593 describes a process for the production of casting molds for metal casting, in which one or more layers of a flowable slip are sprayed onto permanent models and backfilled with a chamotte layer before curing.
  • the slip contains, in addition to additional solvent and anti-settling agents, the hardener, so that the slip can harden within a short time before e.g. on a steep wall surface of the model.
  • the above-mentioned procedure is particularly suitable for casting parts with large dimensions, the surface structure of the models being reproduced accurately and precisely in the casting.
  • the method has the disadvantage that the slurry in the mold becomes steadily firmer during the series production of casting molds and clogs the outlet pipes or openings over time. These blockages are due to the fact that the slip contains the hardener mixed in.
  • the obvious solution not to mix the hardener into the slip and subsequently harden it, does not lead to the desired success for several reasons: Either the slip on the vertically arranged outer walls runs too quickly before hardening or it leads to simultaneous gassing with a hardener , such as B. ammonia, a difficult to solve environmental pollution.
  • the application of the flowable ceramic mass - which is also referred to below as a slip - to the model is carried out in a manner known per se with the aid of tools which are known per se in centrifugal or spraying technology.
  • the mass generally exits under pressure from the nozzle or a corresponding outlet opening. By moving it back and forth over the surface of the model, the mass is evenly distributed on the surface and then sanded directly.
  • Sanding is carried out with a granular, refractory material, e.g. calcined kaolin or enamel mullite.
  • the grain size of the sanding material is preferably between 0.12 and 0.25 mm. However, fractions of the grain size spectrum between 0.07 and 1 mm can also be used, which are preferably applied in such a way that the fractions become coarser from the inside out.
  • the sanding material is mixed with the hardener in a previous work process.
  • the amount of hardener contained in the sanding material largely depends on the type of hardener. In general, liquid amines are used as hardeners at room temperature, of which up to 2% by weight can be mixed evenly into the sanding material without segregation occurring. If necessary, the sanding material is still a fine-grained, highly absorbent material, such as finely divided silica, e.g. Aerosil @, mixed with; this keeps the sanding material free flowing.
  • the sanding material is also sprayed onto the slip layer using tools known from spraying and centrifugal technology.
  • tools known from spraying and centrifugal technology the dimensions of the nozzles and pipes in these tools must be adapted to the grain sizes of the sanding material.
  • the sanding takes place immediately after the slip is sprayed on, so that the individual grains of the sanding material can penetrate into the slip layer and are held by it.
  • the amount of sanding material to be applied depends on the thickness of the previously applied slip layer, which should if possible be in the millimeter range. So much sanding material is sprayed on until it no longer sticks to the surface of the applied layer.
  • the process of applying the slip layer with subsequent sanding can be repeated one or more times in the manner described, depending on the overall thickness of the complete casting mold.
  • the overall thickness is generally at 4 to 8 mm, but it can also be thicker.
  • the slip contains a partially condensed, hydroxyl-containing alkyl silicate as a binder.
  • Corresponding alkyl silicates are known per se; they are produced by partial hydrolysis of partially condensed alkyl silicates which have an SiO 2 content between 35 and 51% and contain up to 10 Si-O groups.
  • the partial hydrolysis which is known per se and is not the subject of the present invention, gives rise to compounds having an SiO 2 content between 8 and 35%, preferably between 18 and 25% by weight. These hydrolyzates contain, statistically distributed, ester and hydroxyl groups.
  • the alkyl radicals of the alkyl silicates mentioned preferably have 1 to 8 carbon atoms.
  • the mentioned partially condensed alkyl silicates containing hydroxyl groups can be partially replaced by partially condensed alcoholates of aluminum, zirconium or titanium, or by mixtures of these compounds. Suitable compounds from this class of compounds are mentioned, for example, in DE-A-2 204 531. Mixtures of these alcoholates with the above-mentioned partially condensed alkyl silicates can also be used.
  • the slip can also contain an inert organic solvent in which the binder is soluble. It is thus possible to keep the slip layer moist longer, so that the time for the subsequent sanding can be extended.
  • High-boiling alcohols with boiling points of> 120 ° C such as e.g. the alkyl ethers of ethylene glycol.
  • the solvents are used in amounts between 5 and 50% by weight, preferably between 20 and 30% by weight.
  • the refractory substances further contained in the slip are preferably refractory oxides or silicates, such as the electro-melt products based on aluminum oxide, silicon dioxide, zirconium oxide or mullite, or minerals such as zirconium silicate, sillimanite, chromium-containing sands or quartz sand or similar substances as a single part or as a mixture with one another .
  • refractory oxides or silicates such as the electro-melt products based on aluminum oxide, silicon dioxide, zirconium oxide or mullite, or minerals such as zirconium silicate, sillimanite, chromium-containing sands or quartz sand or similar substances as a single part or as a mixture with one another .
  • These refractory materials are contained in the slip in amounts between 50 and 95% by weight, preferably between 70 and 90% by weight.
  • the grain size of these substances can be up to 0.12 mm; however, grain sizes up to 0.07 mm are generally used, while the preferred range is between 0 and 0.04 mm.
  • the slip can also contain an anti-settling agent if this appears necessary due to the composition, the grain size and the material used, so that there is no separation between the binder and the refractory material.
  • Substances are used as anti-settling agents which are known from painting technology as thixotropic or thickening agents.
  • Montmorillonite-based substances e.g. with organic solvent, such as. B. a glycol-ethanol mixture, swollen bentonites or organic montmorillonite derivatives; fumed silica; Cellulose esters, e.g. Ethyl cellulose or cellulose ether; resinous products based on hardened castor oil, talc, mica or mixtures of these or similar substances.
  • the amount of anti-settling agent to be added can vary within wide limits depending on the density or on the type and amount of the refractory material used and on the binder.
  • the quantitative ratio of liquid binder to dry refractory to anti-settling agent is expediently set so that the ceramic mass has a sprayable or centrifugable consistency on the one hand, but also adheres to steep model walls and does not run down.
  • Mixtures are suitable, for example, in which the ratio of binder-I + anti-settling agent: highly refractory material, depending on the refractory material used and the spraying apparatus, is used, for example.
  • Deviations from these quantitative ratios are possible since the optimal flow and setting properties of the ceramic composition used according to the invention depend not only on the type and amount of the binders used and the anti-settling agents, but also on the specific surface of the high-refractory grains used.
  • the applied mass solidifies through chemical hardening.
  • This hardening is based on shifting the pH of the binder to a range of rapid gel formation. In general, this range is close to the neutral point. Since the binder mixtures are usually acidic, all substances that use acid act as hardeners.
  • substances can also be used as hardeners whose reaction products with acids are less acidic than the starting mixture.
  • These include e.g. B. the salts of carbonic acid such as calcium carbonate and acid-reacting metals such as e.g. Zinc.
  • the amines known as hardening agents are preferably used as chemical hardening agents and mixed with the sanding material. Suitable amines here are both primary and also secondary or tertiary amines. The only important thing for the hardening properties is the condition that they or their solutions consume acid (shift the pH value into the neutral range). As stated above, other, basic reacting, inorganic or organic compounds can also be used as hardeners, e.g. the salts or hydroxides of the alkali or alkaline earth metals or ammonia. If necessary, they can also be mixed as solid substances with the sanding material.
  • the preparation was carried out analogously to the preparation of the spray slip A, with the difference that 200 g of a calcined aluminosilicate (commercial product Molochite @ 200) was used instead of the melt mullite.
  • Viscosity 21 sec flow time, cup DIN 4.
  • the production was carried out analogously to the production of the spray slip A, with the difference that 380 g of a zirconium silicate DIN 100 were used instead of the melt mullite.
  • Viscosity 19 sec flow time, DIN cup 4.
  • the individual mixtures were prepared by mixing the respective components.
  • the model surface to be imaged was first sprayed with a diethanolamine / water mixture in a ratio of 1: 2; then slip and sanding were applied alternately.
  • the slip was sprayed from a paint spray gun with a 2 mm diameter nozzle at a pressure of 24.5 104 to 29.4 10 "Pa (1.5 to 2 atm).
  • the sanding material was applied from a «Putzmeister» gun at a pressure of less than 14.7.104 Pa (0.5 atm).
  • the first to fifth layers were applied to the model with the spray slip A alternating with the sanding 1 within about 5 minutes.
  • the 6th slip layer is backfilled with a water glass-chamotte mixture in a known manner. After another 5 to 10 minutes, the shape could be lifted off. It had good green strength and could then be fired as usual.
  • the finished mold was cast with steel GS 42 Cr Mo 4 and delivered a casting with high dimensional accuracy and a very smooth surface.
  • Example 2 The procedure was as in Example 1, but the first to fifth layers were applied alternately with the sanding material 2.
  • the mold obtained dried somewhat more slowly than the mold obtained in Example 1, but otherwise it had the same properties.
  • Example 1 The mold was produced analogously to that given in Example 1.
  • Spray slip A which had already been stored for 24 hours, was used as the spray slip; Sanding was carried out with sanding material 3.
  • the shape obtained had the same properties as the shape of Example 1.
  • Example 3 The procedure of Example 3 was repeated with the difference that the sanding Mix 4 was used. The results are analogous to those of Example 3.
  • Example 3 The procedure of Example 3 was repeated with the difference that the sand mix 5 was used. The results are analogous to those of Example 3.
  • a total of ten layers were applied to the model using a spray slurry A stored for 24 hours.
  • Sanding was carried out for the first and second layers with the sanding mixture 1, for the third, fourth and fifth layer with the sanding mixture 4 and for the sixth to tenth layer with the sanding mixture 6.
  • the production of the mold in the manner described required approx. 12 up to 14 minutes.
  • An aluminum-silicon alloy was cast in the mold, which provided a casting with high dimensional accuracy and a very smooth surface.
  • Example 1 The procedure of Example 1 was repeated with the difference that the spray slip B and the sanding material 5 were used. Shapes with the same properties as in Example 1 were obtained.
  • Example 1 The procedure of Example 1 was repeated with the difference that the spray slip C and the sanding material 3 were used.
  • a chrome-molybdenum steel poured out in the shape obtained had a very smooth surface and good dimensional accuracy.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Paints Or Removers (AREA)
EP82109138A 1981-10-30 1982-10-04 Verfahren zur Herstellung von Giessformen für Metallguss Expired EP0078408B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3143036 1981-10-30
DE19813143036 DE3143036A1 (de) 1981-10-30 1981-10-30 "verfahren zur herstellung von giessformen fuer den metallguss"

Publications (3)

Publication Number Publication Date
EP0078408A2 EP0078408A2 (de) 1983-05-11
EP0078408A3 EP0078408A3 (en) 1984-03-28
EP0078408B1 true EP0078408B1 (de) 1986-08-06

Family

ID=6145170

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82109138A Expired EP0078408B1 (de) 1981-10-30 1982-10-04 Verfahren zur Herstellung von Giessformen für Metallguss

Country Status (5)

Country Link
US (1) US4715895A (enrdf_load_stackoverflow)
EP (1) EP0078408B1 (enrdf_load_stackoverflow)
JP (1) JPS5884637A (enrdf_load_stackoverflow)
CA (1) CA1193069A (enrdf_load_stackoverflow)
DE (2) DE3143036A1 (enrdf_load_stackoverflow)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5147830A (en) * 1989-10-23 1992-09-15 Magneco/Metrel, Inc. Composition and method for manufacturing steel-containment equipment
US5422323A (en) * 1994-04-15 1995-06-06 Magneco/Metrel, Inc. Nonhazardous pumpable refractory insulating composition
US11655190B2 (en) 2016-06-28 2023-05-23 Taiheiyo Cement Corporation Hydraulic composition for additive manufacturing device, and process for producing casting mold

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2851752A (en) * 1957-04-08 1958-09-16 Gen Motors Corp High strength investment casting mold
US3232771A (en) * 1962-06-29 1966-02-01 John W Pearce Molds and methods of preparing same
FR1435264A (fr) * 1964-03-26 1966-04-15 Perfectionnements à la préparation des moules céramiques
US3432312A (en) * 1965-09-08 1969-03-11 Howmet Corp Refractory mold composition and method
US3428465A (en) * 1965-10-19 1969-02-18 Stauffer Chemical Co Preparation of molds
US4059453A (en) * 1973-10-03 1977-11-22 Dynamit Nobel Ag Method of making molds for the casting of metals
SE7704162L (sv) * 1976-04-22 1977-10-23 United Technologies Corp Kalciumoxidmodifierat keramiskt skalformsystem
JPS53114811A (en) * 1977-03-04 1978-10-06 Ebara Mfg Method of manufacturing molds for ceramic shell molding
JPS5617156A (en) * 1979-07-18 1981-02-18 Kubota Ltd Reinforcing method of ceramic shell mold

Also Published As

Publication number Publication date
EP0078408A2 (de) 1983-05-11
DE3143036A1 (de) 1983-05-05
JPH0431775B2 (enrdf_load_stackoverflow) 1992-05-27
JPS5884637A (ja) 1983-05-20
EP0078408A3 (en) 1984-03-28
CA1193069A (en) 1985-09-10
DE3272464D1 (en) 1986-09-11
US4715895A (en) 1987-12-29

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