EP3852951A1 - Casting core for casting moulds, and method for the production thereof - Google Patents
Casting core for casting moulds, and method for the production thereofInfo
- Publication number
- EP3852951A1 EP3852951A1 EP19773055.9A EP19773055A EP3852951A1 EP 3852951 A1 EP3852951 A1 EP 3852951A1 EP 19773055 A EP19773055 A EP 19773055A EP 3852951 A1 EP3852951 A1 EP 3852951A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- core
- casting
- binder
- mold
- ceramic particles
- 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.)
- Pending
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/10—Cores; Manufacture or installation of cores
-
- 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
-
- 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
- B22C1/185—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 containing phosphates, phosphoric acids or its derivatives
-
- 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
- B22C1/186—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 contaming ammonium or metal silicates, silica sols
-
- 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
Definitions
- Casting core for casting molds and process for its production
- the present invention relates to a casting core for casting molds, the casting core comprising a core core and a core jacket arranged around the core core.
- the core jacket contains or consists of ceramic particles bound with a binder.
- the core core contains ceramic particles bound with a binder as well as one or more placeholder elements.
- the / the placeholder element (s) is / are at least partially thermally decomposable.
- the present invention also relates to a method for producing the casting core according to the invention and the use of the casting core according to the invention.
- Casting cores or cores are used when casting components in molds in order to keep the cavities provided in the later component clear when filling the mold.
- the casting cores must have the necessary strength and remain dimensionally stable during the casting process. Soaking the casting cores with melt when casting with increased pressure must be closed. In order to obtain a good casting surface, additional requirements are placed on the core material. Here, as little as possible wetting between the melt and the casting core and a smooth, chemically suitable surface is advantageous. Particularly with casting cores for the production of a complex inner shape, good disintegration is required in order to ensure the removal of the core material from the component after casting.
- refractory fillers e.g. quartz sand, zircon sand, aluminosilicates, but also inorganic hollow spheres
- an organic e.g. synthetic resin, protein binder
- inorganic binder silicate binder, phosphate binder
- the shaping can be done by pressing, core shooting or casting.
- the surface of the cores can be improved by applying coatings.
- the thermal decomposition of the organic binder during the casting process weakens the core structure and enables the core material to be removed from the casting, but is also associated with the emission of environmentally harmful gases.
- a casting core for casting molds which comprises a core core and a core shell arranged around the core core.
- the core jacket contains or consists of ceramic particles bound with a binder.
- the core core contains ceramic particles bound with a binder as well as one or more placeholder elements.
- the placeholder element is or the placeholder elements are at least partially thermally decomposable.
- the casting core according to the invention advantageously comprises several parts, namely an inner part, the core core, and an outer part, the core jacket. Due to this core structure with a core jacket which is in contact with the melt and a core core, the casting core according to the invention is optimally adapted to the different requirements during and after a casting process. Due to the presence of the thermally decomposable placeholder elements in the core core, the core core can be destabilized by thermal stress, which simplifies the removal of the casting core from the casting. Due to the heat input during the casting process, which is, for example, at a temperature in the range from 300 ° C to 1500 ° C, the placeholder element or the placeholder elements are thermally decomposed, e.g.
- the thermally decomposable placeholder element (s) are only arranged in the core core and not in the core shell, the core shell or the casting core has a dense and mechanically solid surface which is suitable for contact with the melt in the Casting process is suitable, which is why the casting core remains dimensionally stable during the casting process.
- the functionality of the material composition in the different core areas can be adapted to the opposite requirements.
- fillers or ceramic particles can be used in the jacket, which have a low interaction with the melt.
- a lower porosity and higher mechanical strength can be provided in the core jacket.
- the thermal properties can be selected by the fillers used in the core jacket so that, depending on the casting temperature and the amount of heat input, the core soul is destabilized at different times. This decoupling enables high process reliability and good casting quality to be achieved.
- the thermally decomposable placeholder element (s) reduce the amount of inorganic fillers or ceramic particles that may have to be disposed of and reduce the weight of the cores.
- a preferred embodiment of the casting core according to the invention is characterized in that the ceramic particles of the core shell and / or the ceramic particles of the core core are selected from the group consisting of quartz sand particles, zircon sand particles, aluminosilicate particles, mullite particles, inorganic hollow spheres, alumina particles and mixtures thereof.
- the thermal properties can be influenced in such a way that, depending on the casting temperature and the amount of heat input, the core soul is destabilized at different times.
- the speed of the temperature rise in the core core and thus the beginning of the destruction of the material cohesion in the core core can be set in this way via the thermal properties of the core shell.
- the ceramic particles of the core shell and / or the ceramic particles of the core core have an average particle diameter of 0.5 miti to 500 miti. The average particle diameter can be determined, for example, by means of laser diffraction.
- binder of the core shell and / or the binder of the core core is selected from the group consisting of
- inorganic binders preferably silicate binders, e.g.
- a further preferred embodiment of the casting core according to the invention is characterized in that the placeholder element (s) from (or at) a temperature in the range from 300 ° C. to 1500 ° C., preferably from (or at) a temperature in the range of 400 ° C to 1400 ° C, preferably from (or at) a temperature in the range from 500 ° C to 1300 ° C, is / are at least partially thermally decomposable.
- the placeholder element (s) is / are at least partially thermally decomposable from a temperature in a range of 300 ° C. to 1500 ° C. is to be understood in such a way that the placeholder element (s) are separated any temperature in the range of 300 ° C to 1500 ° C decomposed or partially decomposed.
- the placeholder element or the placeholder elements can decompose from a temperature of 800 ° C, which means that the placeholder element or the placeholder elements can / are thermally decomposable at a temperature> 800 ° C.
- Thermal decomposition can e.g. a burnout, e.g. a partial burnout or a residue-free burnout of the placeholder element or the placeholder elements.
- the placeholder element (s) is / are preferably thermally decomposable or (completely) thermally decomposable from (or at) a temperature in the range from 300 ° C. to 1500 ° C. It is also possible for the placeholder element (s) to be thermally decomposable over the entire temperature range from 300 ° C. to 1500 ° C.
- the placeholder element (s) can be burned out, preferably can be burned out without residue.
- the placeholder element (s) is / are selected from the group consisting of wood foam elements
- Polymer foam elements Polystyrene beads, polymer granules and mixtures thereof.
- the core core consists of the ceramic particles bound with the binder and the placeholder element (s).
- a further preferred embodiment is characterized in that the core jacket and the core core have pores with an average pore size of 1 pm to 50 pm, the core jacket having a lower porosity than the core core.
- the average pore size and / or the porosity can e.g. are determined by means of mercury porosimetry.
- the core jacket has a thickness of 3 mm to 15 mm, preferably 3 mm to 10 mm, particularly preferably 3 mm to 7 mm.
- the speed of the temperature rise in the core core and thus the beginning of the destruction of the material cohesion in the core core can be set via the thickness of the core shell. This ensures increased pressure resistance of the core during mold filling and destabilization of the core after sufficient heat input into the core.
- the core core has a diameter of 5 mm to 100 mm, preferably 10 mm to 100 mm, particularly preferably 15 mm to 100 mm.
- the present invention also relates to a method for producing a casting core according to the invention, in which
- the placeholder element (s) (preferably from or at a temperature in the range from 300 ° C. to 1500 ° C.) is / are at least partially thermally decomposable
- the dried core core of the casting core is inserted into a second casting mold, which has the negative contour of the casting core to be produced, and then a second aqueous, ceramic suspension, which comprises ceramic particles, a binder and water, is poured into this second casting mold becomes,
- the second ceramic suspension located in the second casting mold is solidified to form a core shell of the casting core
- the casting core comprising the core core and the core shell is removed from the second casting mold and then dried.
- inorganic binders based on gypsum, cement, phosphate or silica can be used. Binder based on water glass can be gassed with carbon dioxide after shaping. The water glass reacts with the formation of colloidal silica and sodium carbonate and this strengthens the suspension to the corresponding part of the casting core. In suspensions with water glass or colloidal silica sol as a binder, a solidification can also be obtained by shifting the pH to the neutral range (for example by adding an acid) or drying. After shaping, excess water and bound water, which can be split off at the required casting temperature of the molten metal and which could impair the casting quality, must be removed. This is done by drying. If the required drying temperature is higher than the temperature resistance of the placeholder elements used, partial thermal decomposition of the placeholder elements begins when drying and the porosity or instability in the core core is increased.
- Drying in steps c) and f) is preferably carried out at a temperature from 50 ° C. to 300 ° C., particularly preferably from 90 ° C. to 200 ° C., and / or over a period of 0.1 to 10 hours, preferably from 0.5 to 5 hours, particularly preferably from 1 to 3 hours. Drying can be carried out over several steps, for example a low temperature being selected in the first drying step and a higher temperature being selected in the second drying step.
- the dried core core is preferably provided with core brands (for positioning the core core in the second mold).
- the core brands then allow the exact positioning of the core core within this second mold when the dried core core of the casting core is inserted into the second casting mold, so that the core core later has the desired position in the finished casting core.
- a preferred variant of the method according to the invention is characterized in that in step a) a mixture of a first aqueous, ceramic suspension which comprises ceramic particles, a binder and water, and a plurality of placeholder elements, preferably polystyrene beads, are produced. is set and the mixture is then poured into a first casting mold, which has the negative contour of a core core of the casting core to be produced.
- a further preferred variant of the method according to the invention is characterized in that in step a) a mixture of a first aqueous ceramic suspension comprising ceramic particles, a binder and water, and a placeholder element, preferably a wood foam element or a polymer foam element , is produced in a first casting mold, which has the negative contour of the core core of the casting core to be produced, with the placeholder element first being cut into the shape of the core core and placed in the first casting mold and then the placeholder element with the first aqueous, ceramic Suspen sion is infiltrated and / or cast.
- the present invention also relates to the use of a casting core according to the invention in a method for casting one or more components.
- a core mass based on a phosphate binder is produced as follows: 60% "Wirovest" phosphate binder (BEGO) and 40% quartz powder are stirred into water until a flowable consistency is obtained.
- a reticulated foam (polyether-based dryfeel, pore size 15 ppi , Eurofoam) is cut in the form of the core core, inserted into a mold and infiltrated with the core material produced and cast. After the beginning of solidification, the component is removed from the mold.
- the core core is dried (at 90 ° C. to remove excess water, then at 180 ° C for one hour) and inserted in a divisible form that reflects the geometry of the core.
- the core core is cast with the core mass. After solidification and After demolding, the core is dried at a temperature of 180 ° C for one hour.
- Polystyrene beads are stirred into a ceramic mass consisting of 88.5% phosphate binder "Wirovest” (BEGO) and 11.5% demineralized water and poured into a mold for the core core.
- the hardened component is shaped and divided into parts Insert the core mold and cast the following ceramic mass: 40% mullite (Symulox M72 K0, Nabaltec, average particle size between 7-15 pm) and 60% phosphate binder "Wirovest” (BEGO) are stirred into water until a flowable mass is obtained. After solidification, the core is removed from the mold and dried at 100 ° C.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Mold Materials And Core Materials (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102018215957.2A DE102018215957A1 (en) | 2018-09-19 | 2018-09-19 | Casting core for casting molds and process for its production |
PCT/EP2019/075170 WO2020058402A1 (en) | 2018-09-19 | 2019-09-19 | Casting core for casting moulds, and method for the production thereof |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3852951A1 true EP3852951A1 (en) | 2021-07-28 |
Family
ID=67999656
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19773055.9A Pending EP3852951A1 (en) | 2018-09-19 | 2019-09-19 | Casting core for casting moulds, and method for the production thereof |
Country Status (5)
Country | Link |
---|---|
US (1) | US11590564B2 (en) |
EP (1) | EP3852951A1 (en) |
CN (1) | CN112739476B (en) |
DE (1) | DE102018215957A1 (en) |
WO (1) | WO2020058402A1 (en) |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3568723A (en) * | 1967-06-23 | 1971-03-09 | Du Pont | Metal-ceramic composite structures |
FR1584065A (en) * | 1968-07-30 | 1969-12-12 | ||
DE19918908A1 (en) * | 1999-04-26 | 2000-11-02 | Fraunhofer Ges Forschung | Core for casting a component having a closed hollow cavity comprises a hollow body formed by powder and binder suspension application onto a support and then sintering |
DE10327272A1 (en) | 2003-06-17 | 2005-03-03 | Generis Gmbh | Method for the layered construction of models |
US8540009B2 (en) * | 2009-02-23 | 2013-09-24 | GM Global Technology Operations LLC | Hollow sand cores to reduce gas defects in castings |
CN101716650A (en) * | 2009-12-17 | 2010-06-02 | 浙江红马铸造有限公司 | Composite sand core and manufacturing method thereof |
JP2013071169A (en) | 2011-09-29 | 2013-04-22 | Hitachi Ltd | Ceramic core for precision casting, and method for manufacturing the same |
JP6141539B2 (en) | 2013-10-19 | 2017-06-07 | ピーク ドイチュラント ゲゼルシャフト ミット ベシュレンクテル ハフツングPeak Deutschland GmbH | Method for producing a lost core or molded product for the production of a casting |
CA2885074A1 (en) * | 2014-04-24 | 2015-10-24 | Howmet Corporation | Ceramic casting core made by additive manufacturing |
CN104550756B (en) * | 2014-12-26 | 2017-01-18 | 中核苏阀横店机械有限公司 | Sand core of pipe mould |
DE102016119399A1 (en) * | 2015-10-16 | 2017-04-20 | Ksm Castings Group Gmbh | Casting core for a pump housing, in particular for a housing of a high-pressure pump |
CN107052254A (en) * | 2016-11-30 | 2017-08-18 | 安徽应流集团霍山铸造有限公司 | It is a kind of to strengthen a kind of technique device of its core sand deformability and collapsibility |
-
2018
- 2018-09-19 DE DE102018215957.2A patent/DE102018215957A1/en active Pending
-
2019
- 2019-09-19 CN CN201980061447.0A patent/CN112739476B/en active Active
- 2019-09-19 WO PCT/EP2019/075170 patent/WO2020058402A1/en unknown
- 2019-09-19 EP EP19773055.9A patent/EP3852951A1/en active Pending
- 2019-09-19 US US17/250,827 patent/US11590564B2/en active Active
Also Published As
Publication number | Publication date |
---|---|
US11590564B2 (en) | 2023-02-28 |
CN112739476A (en) | 2021-04-30 |
WO2020058402A1 (en) | 2020-03-26 |
US20210213514A1 (en) | 2021-07-15 |
CN112739476B (en) | 2023-03-28 |
DE102018215957A1 (en) | 2020-03-19 |
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Effective date: 20210309 |
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Owner name: FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V. |