EP0945201A1 - Verfahren zur Herstellung eines Gusskernes, zur Bildung eines zu Kühlzwecken vorgesehenen Hohlraumes innerhalb eines Gussteils - Google Patents
Verfahren zur Herstellung eines Gusskernes, zur Bildung eines zu Kühlzwecken vorgesehenen Hohlraumes innerhalb eines Gussteils Download PDFInfo
- Publication number
- EP0945201A1 EP0945201A1 EP98810250A EP98810250A EP0945201A1 EP 0945201 A1 EP0945201 A1 EP 0945201A1 EP 98810250 A EP98810250 A EP 98810250A EP 98810250 A EP98810250 A EP 98810250A EP 0945201 A1 EP0945201 A1 EP 0945201A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- casting
- core
- roughness
- cooling
- roughened
- 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.)
- Granted
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/18—Finishing
Definitions
- the invention relates to a method for producing a cast core, the to form a cavity provided for cooling purposes within a casting is used, through which a cooling medium is conductive and the cavity create enclosing surface areas via predeterminable heat transfer blessings between the coolant and the casting.
- Casting cores are molded parts provided in a mold, which are placed in the mold Displace cast, solidifiable material and in this way in the cast End product, the casting form cavities.
- end products concern
- turbine blades which are very common in a gas turbine system exposed to high temperatures.
- these are provided with internal cooling channels in a manner known per se, a cooling medium, preferably cooling air or water vapor, for cooling purposes, is directed.
- a cooling medium preferably cooling air or water vapor, for cooling purposes
- combustion chamber walls targeted cooling and to provide them with cooling channels accordingly.
- a major advantage of rough surfaces in terms of a desired increase in the heat transfer from a heated component to a cooling medium compared to the previously known measures of using ribs and pins or similar heat transfer-increasing internals lies essentially in the significantly lower pressure loss that occurs when flowing through of the cooling medium through a roughened "cooling channel.
- the ordinate of the diagram shown in FIG. 1 shows the drag coefficient f that a flow has when flowing through a flow channel as a function of the Reynolds numbers Re plotted on the abscissa of the diagram.
- the graphs a to e entered in the diagram represent flow situations for different types of fins, in which a flow flows through a flow channel provided with fins.
- the solid line corresponds to the flow of a flow channel with a smooth surface.
- the dashed line plotted immediately above the solid line represents a flow case in which the flow channel has a roughened surface with a roughness ratio R / k S of 60.
- R here means the hydraulic radius of the flow channel and k S corresponds to the size of the equivalent sand grain roughness the surface.
- the ratio R / k S of 60 corresponds to a roughness increase of approx. 80 ⁇ m.
- FIG. 2 shows a diagram showing the thermal power "of turbulators, such as fins, in contrast to a roughened surface.
- the values plotted on the ordinate of the diagram in FIG. 2 G ( St / St 0 ) / ( f / f 0 ) 1 3rd show the relative increase in heat transfer for the same pumping power in the system. These values therefore give the Thermal performance "of the system (the fins) and thus their relative quality compared to the smooth channel.
- the molded parts equipped with cooling channels are preferably produced using a casting process manufactured and serve, for example, as to be subjected to heat Assemblies of gas turbine plants.
- the cooling channels some of which are very delicate, for example within a turbine blade, are after completion of the Turbine blade from outside difficult or not at all for local reworking accessible. Solutions have to be found with which one desired surface roughness, the surface quality of which determined Roughness values must correspond to can be obtained. Because the concerned End products have to be manufactured as part of a casting process the desired surface roughness can be found before or during the casting process or during cooling of the cast end product to obtain.
- the invention is therefore based on the object of taking measures that a desired surface roughness during the casting process Can produce end product.
- a desired surface roughness during the casting process Can produce end product.
- inaccessible Cavities within the end product, which are preferably designed as cooling channels are already over a desired surface roughness without post-treatment steps feature.
- the invention is based on the idea of producing the casting process Voids within the casting cores to be provided within the final product to be manufactured to be covered with an artificial roughness that occurs during the casting process transfers to the surface of the end product to be produced, preferably on those surface areas that enclose a cavity that in the finished Casting forms a cooling channel.
- the formation of a cavity within of the finished product provided by prior processing on its Surface can be roughened.
- the one transferred to the surface of the cast core The degree of roughness can be applied, for example, using a core tool.
- the surface of the core tool is eroded to a desired level using spark erosion Measure roughened.
- the degree to be applied to the core tool Roughness can be caused by the electrical voltage to be applied to the spark electrode and / or by choosing a distance between the spark electrode and the surface to be roughened Core tool can be set specifically.
- the surface roughness applied in this way to the surface of the cutting tool is transferred as part of the manufacturing process for the casting core on the casting core and then during the casting process and the subsequent cooling of the end product to the corresponding inner surface contour of the end product.
- Cast cores are usually made from a moldable mass that must be fired to harden. Shaped cast cores are considered as before firing green cores "and can be roughened to bring about a surface roughness in this or in the fired state by means of sandblasting or targeted further roughening techniques, such as grinding and emery processes.
- the casting core can also be used as a green core with the help of a cold or heated one Tool that has a defined roughness structure by ordinary Pressing the surface of the cast core to be roughened.
- the surface roughness should be adjusted so that it meets the following flow conditions, that prevail within the cooling channel and the desired Heat transfer coefficient is adjusted.
- the associated roughness variable R / k S can be read from the diagram according to FIG. 3 (referred to below) and used for the production of the core tool.
- the diagram in FIG. 3 shows the dependence of the resistance coefficient f on the Reynolds number Re for different roughness heights k s / 2R.
- the smooth channel has a very small roughness, typically with a roughness Reynolds number Re k ⁇ 5. This relationship is also known from the books by Hays + Crawford, Convectiv Heat and Mass Transfer ", Mc Graw Hill Inc., ISBN 0-07-033721-7, 1993 or O. Tietjens, Fluid Mechanics, Part 2 ", Springer Verlag, 1970.
- the curves entered in FIG. 3 each assume a constant value for the resistance number f for different values of the roughness height k s / 2R, provided that they are to the right of this line in the diagram.
- the resistance coefficient f increases by about 33%.
- FIGS. 5 are cross sections through a cooling wall surface in the partial figures a and b 3 shown, which is each provided with ribs.
- two ribs 1, 2 stand vertically above the cooling wall surface 3 and for the cooling flow KS flowing over the fins 1, 2 represents a resistance.
- the flow KS passing through the cooling channel is from each rib train detached from the wall 3, behind each rib train in the flow direction Form leewer vortex 4 and in the direction of flow in front of each rib line accumulation vortex 5.
- FIGS. 4a and 4b show that the length L of the separation area, in which the flow is spaced from the cooling wall after each rib pull, is shortened by the wall roughness. This means that in roughened case "the ribs can be brought closer together and thus the heat load per length of the component can be increased.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
Description
- Fig. 1
- Diagrammdarstellung zur Darstellung des Widerstandsbeiwertes f von verschieden ausgebildeten Kühlkanälen,
- Fig. 2
- Diagrammdarstellung der Gütefunktion von unterschiedlich ausgestalteten Kühlkanälen,
- Fig. 3
- Widerstandsbeiwert als Funktion der Reynoldszahl für verschiedene Wandrauhigkeiten und
- Fig. 4a, b
- Tabellen zur Erhöhung des Wärmeübergangs bei einer gezielten Einbringung von Rauhigkeiten für verschiedene Reynolds-Zahlen und
- Fig. 5 a, b
- schematisierte Querschnittsdarstellung einer mit Rippenzügen versehenen Wand ohne bzw. mit Oberflächenrauhigkeit.
- 1
- Rippenzug
- 2
- Rippenzug
- 3
- Kühlwandoberfläche
- 4
- Leewirbel
- 5
- Stauwirbel
- L
- Länge des Ablösegebietes
- KS
- Kühlströmung
Claims (11)
- Verfahren zur Herstellung eines Gußkernes, der zur Bildung eines zu Kühlzwecken vorgesehenen Hohlraumes innerhalb eines Gußteils verwendet wird, durch welchen ein Kühlmedium leitbar ist, wobei der Gußkern Oberflächenbereiche aufweist, in die gezielt eine Oberflächenrauhigkeit eingebracht wird, die sich während des Gießvorganges auf den Hohlraum einschließende Oberflächenbereiche überträgt und zu einer Erhöhung des Wärmeüberganges zwischen Kühlmedium und Gußteil führt.
- Verfahren nach Anspruch 1,
dadurch gekennzeichnet, daß die Oberflächenrauhigkeit des Gußkerns einer gewünschten Wärmeübergangszahl angepaßt wird, die sich bei Überströmen der den Hohlraum einschließenden rauhen Oberflächenbereiche innerhalb des Gußteils mit dem Kühlmedium, vorzugsweise Kühlluft, einstellt. - Verfahren nach Anspruch 1 oder 2,
dadurch gekennzeichnet, daß der Gußkern derart ausgebildet wird, daß sich der Hohlraum innerhalb des Gußteils als Strömungskanal ausbildet, der von aufgerauhten Oberflächenbereichen eingeschlossen wird, deren Oberflächenrauhigkeit durch das Verhältnis aus hydraulischem Radius R des Strömungskanals und der äquivalenten Sandkornrauhigkeit ks bestimmt wird. - Verfahren nach Anspruch 3,
dadurch gekennzeichnet, daß das Verhältnis R/ks vorzugsweise etwa den Wert 60 - 120 annimmt. - Verfahren nach einem der Ansprüche 1 bis 4,
dadurch gekennzeichnet, daß der Gußkern aus einer modellierfähigen Masse besteht, die in einem weiteren Herstellungsschritt zum Aushärten gebracht wird. - Verfahren nach einem der Ansprüche 1 bis 5,
dadurch gekennzeichnet, daß zum Aufrauhen der Oberflächenbereiche des Gußkernes ein Kernwerkzeuges verwendet wird, dessen Oberfläche mittels Funkenerosion gezielt aufgerauht wird.. - Verfahren nach einem der Ansprüche 1 bis 5,
dadurch gekennzeichnet, daß die aufgerauhten Oberflächenbereiche des Gußkerns mittels Sandstrahlen hergestellt werden. - Verfahren nach einem der Ansprüche 1 bis 5,
dadurch gekennzeichnet, daß die aufgerauhten Oberflächenbereiche des Gußkerns mittels Einpressen von Rauhigkeitsstrukturen unter Verwendung kalter oder erwärmter Presswerkzeuge aufgerauht werden. - Verfahren nach Anspruch 6,
dadurch gekennzeichnet, daß das Kernwerkzeug aufgerauht wird, noch bevor es zur Hertstellung des Gußkern verwendet wird. - Verfahren nach einem der Ansprüche 1 bis 9,
dadurch gekennzeichnet, daß das fertiggestellte Gießteil eine mit Kühlkanälen durchsetzte Turbinenschaufel oder Brennkammer ist, deren Kühlkanalwände durch den Gießprozeß eine definierte Oberflächenrauhigkeit erhalten, die der Oberflächenrauhigkeit des Gußkernes entspricht. - Verfahren nach einem der Ansprüche 1 bis 10,
dadurch gekennzeichnet, daß in den Gußkern Auskerbungen eingearbeitet werden, die beim Gießvorgang an der Hohlraumoberfläche des Gießteils Rippenzüge und eine definierte Rauhigkeit entstehen lassen.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP98810250A EP0945201B1 (de) | 1998-03-23 | 1998-03-23 | Verfahren zur Herstellung eines Gussteils mit aufgerauhten Kühlkanälen |
DE59810629T DE59810629D1 (de) | 1998-03-23 | 1998-03-23 | Verfahren zur Herstellung eines Gussteils mit aufgerauhten Kühlkanälen |
US09/268,722 US6374898B1 (en) | 1998-03-23 | 1999-03-17 | Process for producing a casting core, for forming within a cavity intended for cooling purposes |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP98810250A EP0945201B1 (de) | 1998-03-23 | 1998-03-23 | Verfahren zur Herstellung eines Gussteils mit aufgerauhten Kühlkanälen |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0945201A1 true EP0945201A1 (de) | 1999-09-29 |
EP0945201B1 EP0945201B1 (de) | 2004-01-21 |
Family
ID=8236006
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98810250A Expired - Lifetime EP0945201B1 (de) | 1998-03-23 | 1998-03-23 | Verfahren zur Herstellung eines Gussteils mit aufgerauhten Kühlkanälen |
Country Status (3)
Country | Link |
---|---|
US (1) | US6374898B1 (de) |
EP (1) | EP0945201B1 (de) |
DE (1) | DE59810629D1 (de) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6588484B1 (en) * | 2000-06-20 | 2003-07-08 | Howmet Research Corporation | Ceramic casting cores with controlled surface texture |
US20080254162A1 (en) * | 2007-03-28 | 2008-10-16 | Toyoda Gosei Co., Ltd. | Electroformed mold and manufacturing method therefor |
EP2738469B1 (de) | 2012-11-30 | 2019-04-17 | Ansaldo Energia IP UK Limited | Verbrennungskammerteil einer Gasturbine mit wandnaher Kühlanordnung |
DE102017205804A1 (de) | 2017-04-05 | 2018-10-11 | Mahle International Gmbh | Kolben einer Brennkraftmaschine |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS55114435A (en) * | 1979-02-24 | 1980-09-03 | Ishikawajima Harima Heavy Ind Co Ltd | Production of air cooled type gas turbine blade |
SU1435374A1 (ru) * | 1987-06-20 | 1988-11-07 | Предприятие П/Я В-2190 | Керамическа смесь дл изготовлени литейных стержней |
-
1998
- 1998-03-23 EP EP98810250A patent/EP0945201B1/de not_active Expired - Lifetime
- 1998-03-23 DE DE59810629T patent/DE59810629D1/de not_active Expired - Lifetime
-
1999
- 1999-03-17 US US09/268,722 patent/US6374898B1/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS55114435A (en) * | 1979-02-24 | 1980-09-03 | Ishikawajima Harima Heavy Ind Co Ltd | Production of air cooled type gas turbine blade |
SU1435374A1 (ru) * | 1987-06-20 | 1988-11-07 | Предприятие П/Я В-2190 | Керамическа смесь дл изготовлени литейных стержней |
Non-Patent Citations (2)
Title |
---|
DATABASE WPI Section Ch Week 8919, Derwent World Patents Index; Class A88, AN 89-143408, XP002075969 * |
PATENT ABSTRACTS OF JAPAN vol. 004, no. 164 (M - 041) 14 November 1980 (1980-11-14) * |
Also Published As
Publication number | Publication date |
---|---|
US6374898B1 (en) | 2002-04-23 |
DE59810629D1 (de) | 2004-02-26 |
EP0945201B1 (de) | 2004-01-21 |
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