EP0237400B1 - Process for the preparation of ceramic cores - Google Patents

Process for the preparation of ceramic cores Download PDF

Info

Publication number
EP0237400B1
EP0237400B1 EP19870400415 EP87400415A EP0237400B1 EP 0237400 B1 EP0237400 B1 EP 0237400B1 EP 19870400415 EP19870400415 EP 19870400415 EP 87400415 A EP87400415 A EP 87400415A EP 0237400 B1 EP0237400 B1 EP 0237400B1
Authority
EP
European Patent Office
Prior art keywords
core
wax
ceramic cores
mold
mould
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
EP19870400415
Other languages
German (de)
French (fr)
Other versions
EP0237400A1 (en
Inventor
Jacky Pierre Tabardin
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.)
Safran Aircraft Engines SAS
Original Assignee
Safran Aircraft Engines SAS
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
Priority to FR8602700A priority Critical patent/FR2594727B1/en
Priority to FR8602700 priority
Application filed by Safran Aircraft Engines SAS filed Critical Safran Aircraft Engines SAS
Publication of EP0237400A1 publication Critical patent/EP0237400A1/en
Application granted granted Critical
Publication of EP0237400B1 publication Critical patent/EP0237400B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22CFOUNDRY MOULDING
    • B22C9/00Moulds or cores; Moulding processes
    • B22C9/18Finishing
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22CFOUNDRY MOULDING
    • B22C7/00Patterns; Manufacture thereof so far as not provided for in other classes
    • B22C7/02Lost patterns

Description

  • The present invention relates to a process for the preparation of ceramic cores intended for use in precision casting for the casting of parts obtained by methods of the lost wax type.
  • The application of such processes, the general technical knowledge of which is widely spread in the foundry field, is mainly aimed at obtaining high precision parts and is particularly common in the manufacture of aeronautical parts.
  • An example of these applications is provided by the blades of turbines fitted with very elaborate internal cooling devices. The manufacture of such parts by lost-wax casting methods leads to the use of ceramic cores which, to reproduce these cooling devices, necessarily have multiple cavities, thin walls and complex shapes. It also results in a great brittleness of these cores and it follows that multiple manipulations or stresses may cause damage by rupture.
  • The production of wax models coating this type of core in processes of the lost wax type thus encounters implementation difficulties which are not entirely satisfactorily resolved by the procedures applied up to now. In fact, the fragility of the cores prevents the wax from being injected, during the operation of coating the cores with the model wax, at a sufficient pressure which would make it possible to compensate for the volumetric shrinkage of the wax in the massive areas or greater local thicknesses. However, these withdrawals cause defects in shape which are unacceptably represented on the parts and which it is not always possible to plan repeatedly to make corrections.
  • One solution to this problem, which practitioners in the technical field concerned have attempted to apply, consists in manually filling with liquid wax all the cavities of the ceramic cores before said coating operation. But this manual operation, in addition to its disadvantages of implementation due to the costs, the lengthening of the manufacturing cycles, leads to numerous manipulations increasing the risks of deterioration due to the brittleness of the cores and obliges to carry out numerous alterations, while remaining dependent essentially the dexterity of an operator.
  • The method according to the invention aims to solve these problems without being subject to the disadvantages previously encountered. This method is characterized in that before an operation of coating the core with the model wax, an operation of filling with wax the cavities of the core is carried out, during which the said core is enclosed in a flexible mold and the wax liquid is injected into the mold by means of an injection press of suitable power.
  • Other advantages and characteristics of the invention will emerge more clearly from the description which follows of an embodiment of the invention, with reference to the appended drawings in which:
    • FIG. 1 represents a bare ceramic core before the application of the preparation process according to the invention,
    • FIG. 2 represents a model core,
    • FIG. 3 represents a cross section along III-III of the core shown in FIG. 2,
    • FIG. 4 represents a schematic view of the overmolding tool of the model core,
    • FIG. 5 represents a cross section along VV of the tool represented in FIG. 4,
    • FIG. 6 represents a schematic perspective view of the two mold elements,
    • FIG. 7 represents a diagrammatic view of carrying out the filling operation which comprises the process for preparing ceramic cores according to the invention,
    • FIG. 8 represents the operation of finishing the core after filling,
    • - Figure 9 shows an example of a core prepared by the method according to the invention.
  • The ceramic core 1 shown in Figure 1 is an example of application of the invention. This core 1 is used in precision casting for the casting of a turbine blade by a process of the lost wax kind. This type of blade has sophisticated internal cooling devices. The example shown thus shows internal walls 1a and various pins 1 or flow-disturbing elements and stiffeners 1 which delimit internal cavities of the blade. These elements determine the corresponding cavities arranged on the ceramic core 1 which thus has complex and very fine elements from which it also results in great fragility. In a foundry process, of the kind mentioned above, a ceramic core 1 must be coated with model wax. To obtain satisfactory results and avoid unacceptable shape defects due to phenomena of volumetric shrinkage of the wax in massive areas or greater local thicknesses and while the brittleness of the core imposes a limitation on the injection pressure of the wax, it becomes necessary to fill with wax all the cavities of the ceramic core 1.
  • Figures 2 and 3 show a model core 10 which is similar to the prepared core to obtain. This model core 10 is used for the production by molding of a mold made of flexible material, for example of the silicone elastomer type.
  • Figures 4 and 5 show an example of implementation of this operation. Two model cores 10, for example, are placed in a molding box 2 on a starting layer 3. A common molding process using an injection channel 10a arranged on one face of the model core 10 makes it possible to obtain a first part 4 of elastomer mold constituting a face of the mold then a second part 5 of mold constituting a second face of the mole, as shown in FIG. 6. The mold 6 of elastomer thus has the imprints, respectively 6a and 6b, on both sides of a model core 10. An injection channel 6c is also provided on the mold 6.
  • The method according to the invention consists in placing the bare ceramic cores 1 in a mold 6 made of silicone elastomer and in transferring the mold 6 onto the support plate 7a of an injection pressure 7 schematically represented in FIG. 7. A head 7b is fitted onto the mold 6 and injects the liquid wax into the mold 6 where the channels 6c convey the wax by fine channels to the cavities 1a, 1b or 1 of the ceramic core 1. The press 7 used is of power adapted to the process and the adjustment of the injection pressure is between 1 and 5 bars. During the injection, a plate 7c of the press 7 also applies a clamping pressure to the mold 6, the value of which is determined as a function of the setting of the injection pressure.
  • After injection of the wax and removal from the mold, a final touch-up, as shown in Figure 8, eliminates the injection channels connected to the prepared core and Figure 9 shows the prepared core 11 ready for use in which the cavities were filled with wax.
  • The method according to the invention which has just been described has numerous advantages compared to the long and delicate manual operations which it was previously necessary to use. Cycle times are significantly reduced. A manual operation time is estimated at 3 to 6 minutes per nucleus, while the method according to the invention reduces the operation to half a minute per nucleus. The process reduces the handling of nuclei and consequently limits the risks of breakage which are high due to the fragility of the nuclei. The wax deposit obtained is more regular and a repetitive and reproducible quality is obtained.

Claims (3)

1. Process for preparing ceramic cores intended for operations of precision casting of components obtained by processes of the lost-wax type, characterized in that before an operation of coating the core (11) with modelling wax, an operation of filling the cavities in the said core (11) with wax is carried out, during which the said core (11) is enclosed in a flexible mould (6) and the liquid wax is injected into the mould by means of an injection press (7) of suitable power.
2. Process for preparing ceramic cores according to Claim 1, characterized in that the flexible mould (6) employed is made of silicone elastomer and is obtained by overmoulding a dummy core (10) identical in shape with the core (11) to be obtained.
3. Process for preparing ceramic cores according to either of Claims 1 and 2, characterized in that the injection pressure of the press (7) is controlled between 1 and 5 bars and a clamping pressure determined as a function of the injection pressure is applied to the mould (6).
EP19870400415 1986-02-27 1987-02-25 Process for the preparation of ceramic cores Expired EP0237400B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
FR8602700A FR2594727B1 (en) 1986-02-27 1986-02-27 Process for the preparation of ceramic cores
FR8602700 1986-02-27

Publications (2)

Publication Number Publication Date
EP0237400A1 EP0237400A1 (en) 1987-09-16
EP0237400B1 true EP0237400B1 (en) 1989-01-18

Family

ID=9332574

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870400415 Expired EP0237400B1 (en) 1986-02-27 1987-02-25 Process for the preparation of ceramic cores

Country Status (7)

Country Link
US (1) US4732204A (en)
EP (1) EP0237400B1 (en)
JP (1) JPH0438498B2 (en)
DE (1) DE3760041D1 (en)
FR (1) FR2594727B1 (en)
IL (1) IL81696A (en)
IN (1) IN168394B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2823455A1 (en) * 2001-04-17 2002-10-18 Howmet Res Corp Method and device for forming positioning elements on a ceramic core

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2205261B (en) * 1987-06-03 1990-11-14 Rolls Royce Plc Method of manufacture and article manufactured thereby
JPH0317579B2 (en) * 1987-10-31 1991-03-08 Morikawa Sangyo
JPH0565328B2 (en) * 1989-03-28 1993-09-17 Aishin Kako Kk
US5028239A (en) * 1989-05-12 1991-07-02 Nalco Chemical Company Fuel dewatering additives
US5524695A (en) * 1993-10-29 1996-06-11 Howmedica Inc. Cast bone ingrowth surface
US5773039A (en) * 1996-04-01 1998-06-30 Jones; Earl S. Apparatus for multiple wax castings
US6561428B2 (en) * 1997-10-17 2003-05-13 Hand Held Products, Inc. Imaging device having indicia-controlled image parsing mode
DE10310987B3 (en) * 2003-03-07 2004-04-08 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Method for making models, tools or tool inserts comprises directly molding them in open mold mounted on machine tool, molding then being trimmed to its final shape
US7296615B2 (en) * 2004-05-06 2007-11-20 General Electric Company Method and apparatus for determining the location of core-generated features in an investment casting
CA2567936C (en) 2006-11-14 2016-01-05 Atomic Energy Of Canada Limited Device and method for surface replication
EP1930096A1 (en) * 2006-12-07 2008-06-11 Siemens Aktiengesellschaft Methof of manufacturing casting pattern for investment casting of parts containing at least one hollow portion
KR20130008511A (en) * 2010-12-07 2013-01-22 미크로 시스템즈, 인코포레이티드 Investment casting utilizing flexible wax pattern tool
US20110132564A1 (en) * 2009-12-08 2011-06-09 Merrill Gary B Investment casting utilizing flexible wax pattern tool
US20130333855A1 (en) * 2010-12-07 2013-12-19 Gary B. Merrill Investment casting utilizing flexible wax pattern tool for supporting a ceramic core along its length during wax injection
WO2014175940A2 (en) * 2013-03-01 2014-10-30 United Technologies Corporation Gas turbine engine component manufacturing method and core for making same
CN107790644A (en) * 2017-11-09 2018-03-13 东方电气集团东方汽轮机有限公司 A kind of method for preventing Hollow Blade Wax patterns from deforming

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR789721A (en) * 1935-05-08 1935-11-05 Direction indicators for bicycles, motorcycles and carts
GB789721A (en) * 1954-03-09 1958-01-29 Rolls Royce Improvements relating to casting processes for metals
DE1508663B1 (en) * 1966-02-02 1970-06-25
GB2053047B (en) * 1979-07-07 1983-01-26 Rolls Royce Cores for lost wax casting
US4283835A (en) * 1980-04-02 1981-08-18 United Technologies Corporation Cambered core positioning for injection molding
GB2150874B (en) * 1983-12-07 1986-07-09 Rolls Royce Investment casting

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2823455A1 (en) * 2001-04-17 2002-10-18 Howmet Res Corp Method and device for forming positioning elements on a ceramic core

Also Published As

Publication number Publication date
JPH0438498B2 (en) 1992-06-24
EP0237400A1 (en) 1987-09-16
IL81696A (en) 1990-02-09
FR2594727A1 (en) 1987-08-28
US4732204A (en) 1988-03-22
IN168394B (en) 1991-03-23
FR2594727B1 (en) 1988-05-06
IL81696D0 (en) 1987-09-16
DE3760041D1 (en) 1989-02-23
JPS62220244A (en) 1987-09-28

Similar Documents

Publication Publication Date Title
US8915289B2 (en) Ceramic core with composite insert for casting airfoils
US9835035B2 (en) Cast-in cooling features especially for turbine airfoils
EP2777841B1 (en) Ceramic core with composite fugitive insert for casting airfoils
EP2522444B1 (en) Ceramic core with composite insert for casting airfoils
US4417381A (en) Method of making gas turbine engine blades
US4378929A (en) Mold for dental models base
DE2659168C2 (en)
DE102005021666B4 (en) Method and apparatus for determining the position of equipment features generated in the center core in a lost wax casting
DE60300436T2 (en) Process for the production of inserts for steam cooled and hot gas flow exposed components
US4283835A (en) Cambered core positioning for injection molding
US4289191A (en) Injection molding thermoplastic patterns having ceramic cores
US5916271A (en) Hollow jewelry ring having inner round design
US6502801B2 (en) Apparatus and method for molding a core for use in casting hollow parts
US4133371A (en) Casting
US4426402A (en) Method for rapidly producing chocolate forms
US4434835A (en) Method of making a blade aerofoil for a gas turbine engine
US7275585B1 (en) Process for the manufacture by lost wax moulding of parts that include at least one cavity
US4384607A (en) Method of manufacturing a blade or vane for a gas turbine engine
EP1815923A1 (en) Metallic coated cores to facilitate thin wall casting
US2337036A (en) Resilient mold
JP2005028455A (en) Investment casting method, and core and die used therein
JP4781721B2 (en) Recovery method of ceramic core
EP1227905B1 (en) Multipiece core assembly for cast airfoil
US20020148589A1 (en) Ceramic core with locators and method
JP3226674B2 (en) Investment casting method using a core with integral wall thickness control means

Legal Events

Date Code Title Description
17P Request for examination filed

Effective date: 19870316

AK Designated contracting states:

Kind code of ref document: A1

Designated state(s): BE DE FR GB SE

17Q First examination report

Effective date: 19880601

AK Designated contracting states:

Kind code of ref document: B1

Designated state(s): BE DE FR GB SE

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)
REF Corresponds to:

Ref document number: 3760041

Country of ref document: DE

Date of ref document: 19890223

Format of ref document f/p: P

26N No opposition filed
PGFP Postgrant: annual fees paid to national office

Ref country code: BE

Payment date: 19910114

Year of fee payment: 05

PGFP Postgrant: annual fees paid to national office

Ref country code: SE

Payment date: 19910118

Year of fee payment: 05

PG25 Lapsed in a contracting state announced via postgrant inform. from nat. office to epo

Ref country code: SE

Effective date: 19920226

PG25 Lapsed in a contracting state announced via postgrant inform. from nat. office to epo

Ref country code: BE

Effective date: 19920228

BERE Be: lapsed

Owner name: SOC. NATIONALE D ETUDE ET DE CONSTRUCTION DE MOTEU

Effective date: 19920228

EUG Se: european patent has lapsed

Ref document number: 87400415.3

Effective date: 19920904

Format of ref document f/p: F

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

REG Reference to a national code

Ref country code: FR

Ref legal event code: TP

Ref country code: FR

Ref legal event code: CD

PGFP Postgrant: annual fees paid to national office

Ref country code: FR

Payment date: 20040122

Year of fee payment: 18

PGFP Postgrant: annual fees paid to national office

Ref country code: GB

Payment date: 20040128

Year of fee payment: 18

PGFP Postgrant: annual fees paid to national office

Ref country code: DE

Payment date: 20040212

Year of fee payment: 18

PG25 Lapsed in a contracting state announced via postgrant inform. from nat. office to epo

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20050225

PG25 Lapsed in a contracting state announced via postgrant inform. from nat. office to epo

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20050901

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20050225

PG25 Lapsed in a contracting state announced via postgrant inform. from nat. office to epo

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20051031

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20051031