GB2111881A - Investment casting process and mould - Google Patents
Investment casting process and mould Download PDFInfo
- Publication number
- GB2111881A GB2111881A GB08235678A GB8235678A GB2111881A GB 2111881 A GB2111881 A GB 2111881A GB 08235678 A GB08235678 A GB 08235678A GB 8235678 A GB8235678 A GB 8235678A GB 2111881 A GB2111881 A GB 2111881A
- Authority
- GB
- United Kingdom
- Prior art keywords
- mould
- chaplet
- core
- pattern
- outer part
- 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.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/06—Permanent moulds for shaped castings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C21/00—Flasks; Accessories therefor
- B22C21/12—Accessories
- B22C21/14—Accessories for reinforcing or securing moulding materials or cores, e.g. gaggers, chaplets, pins, bars
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
- B22C7/02—Lost patterns
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
- Mold Materials And Core Materials (AREA)
Description
1
GB2 111 881 A
1
SPECIFICATION
Investment casting process and mould
5 The present invention relates to a method of investment casting and to an investment casting mould.
The invention specifically concerns a mould comprising an outer part surrounding an inner core. This type of mould is well known and is used for the 10 casting of hollow parts such as, for example, turbine blades and guide vanes for jet propulsion engines. The core is usually held in position at its extremities within the outer part of the mould by means of supports known as prints extending between the 15 outer part and the core. If the cores are very slender, further supports at intermediate positions may be necessary. These supports are called chaplets and their construction and method of insertion into the mould affects not only the moulding process itself 20 but also the finished moulded article. Such chaplets, more usually constructed of two discs joined by a cylinder, have been extensively used in sand casting moulds for many years.
An existing form of chaplets as used in shell 25 moulds consists of a pin or wire. In the pattern making process, after forming a wax pattern about a ceramic core, by placing the core in the wax pattern die and injecting wax into it, the pin or wire form chaplet is pushed into the wax until it contacts the 30 core. The length of the pins or wires is chosen so that they project slightly from the wax after insertion and locate in the outer part of the mould which is subsequently formed about them. An advantage of the pin or wire chaplet over the earlier disc/cylinder 35 chaplet is that the reduced bulk of the chaplet promotes its fusion with the poured metal during casting.
According to one aspect of the present invention there is provided a method of investment casting 40 using an investment casting block mould having a core including the steps of forming a pattern about the core of the mould, inserting the chaplets into the pattern until they engage the core, forming the outer part of the mould about the pattern, removing the 45 pattern, pouring molten metal into the cavity left thereby to produce a casting into which the material of the chaplets is fused, allowing the molten metal to solidify and removing the outer part and core of the block mould.
50 According to another aspect of the present invention, there is provided a method of investment casting using an investment casting mould having a core including the steps of forming a pattern about the core of the mould, forming chaplets from sheets 55 of expanded metal, inserting the chaplets into the pattern until they engage the core, forming the outer part of the mould about the pattern, removing the pattern, pouring molten metal into the cavity left thereby to produce a casting into which the material 60 of the expanded metal chaplets is fused, allowing the molten metal to solidify, and removing the outer part and core of the mould.
A preferred embodiment of the method of the invention may comprise one or more of the follow-65 ing advantageous features:-
(a) Each chaplet is dimensioned so that a portion of its projects from the wax pattern and subsequently locates in the outer part of the mould.
(b) Each chaplet is a flat strip of expanded metal.
70 (c) Each chaplet is bent in the plane of the surface of the pattern.
(d) Each chaplet of (c) is bent to give the chaplet a 'C' shaped cross section.
(e) Each chaplet of (c) is bent to give the chaplet a
75 'U'shaped cross section.
(f) Each chaplet of (c) is bent to give the chaplet a 'V' shaped cross section.
(g) Each chaplet is made of platinum, or combinations of nickel cobalt and chromium alloys, or
80 such dense metal alloys coated with platinum or other metal of superior oxidation resistance.
(h) The pattern is made of wax, synthetic plastics or other material having a relatively low melting point.
85 (i) The core and mould outer part are made of a ceramic material.
(j) Each chaplet is heated to a temperature above the melting point of the pattern material to ease its passage through the pattern.
90 According to a further aspect of the invention, there is provided an investment casting block mould comprising a core, a mould outer part disposed around and spaced from the core and chaplets extending between the outer part and the core and
95 locating the core within the outer mould part.
According to a still further aspect of the invention, there is provided an investment casting mould comprising a core, a mould outer part disposed around and spaced from the core, and chaplets 100 made of expanded metal extending between the outer part and the core and locating the core within the outer mould part.
A preferred embodiment of the mould of the invention may comprise one or more of the follow-105 ing advantageous features:-
(a) The inner part of each chaplet engages but does not penetrate the core and the outer part of each chaplet locates in the outer part of the mould.
(b) Each chaplet is a flat strip of expanded metal. 110 (c) Each chaplet is bent in the plane of the surface of the mould.
(d) Each bent chaplet of (c) has a 'C' shaped cross section.
(e) Each bent chaplet of (c) has a 'U' shaped 115 cross section.
(f) Each bent chaplet of (c) has a 'V' shaped cross section.
(g) Each chaplet is made of platinum, or combinations of nickel cobalt and chromium alloys, or
120 such dense metal alloys coated with platinum or other metal of superior oxidation resistance.
(h) The pattern is made of wax, synthetic plastics or other material having a relatively low melting point.
125 (i) The core and mould outer part are made of a ceramic material.
The invention also comprises a casting made by the above defined mould and method.
In order that the invention may be more clearly 130 understood, one embodiment of the invention will
2 GB 2 111 881 A
2
now be described, by way of example, with reference to the accompanying drawings, in which
Figure 1 diagrammatically illustrates the manner of formation of a wax pattern about a mould core, 5 Figure 2 diagrammatically illustrates the core of the mould with the wax pattern of Figure 1 formed around it with expanded metal chaplets inserted into the wax,
Figure 3 diagrammatically shows the outer mould 10 part formed about the wax pattern of Figures 1 and 2,
Figure 4 diagrammatically illustrates the mould after the wax has been replaced by the metal of the casting, and
15 Figure 5 illustrates several forms of expanded metal for the chaplets inserted into the wax pattern of Figure 2.
The steps of the production of a vane casting of hollow airfoil section will now be described with 20 reference to the accompanying drawings. The mould to be used effectively comprises two parts, an outer part 1 and a core 2. The core, which is made of ceramic and has an external surface complementary in form to the desired form of the internal surface of 25 the vane, is placed in a pattern die. This is a metal die 3 normally made in several parts and internally machined in complementary fashion to the desired form of the outer surface of the casting to be produced. The core is supported in the die by means 30 of prints 5 which extend from the extremities of the core. The material for making the pattern 6, normally a low melting point substance such as wax or synthetic plastics alternative such as polystyrene, is then injected into the die and allowed to solidify 35 (Figure 1). Thereafter, the die is opened leaving the ceramic core 2 with the pattern 6 formed on it.
Metal chaplets 7 are then inserted into the material of the pattern 6 (Figure 2) until they abuttthe surface of the ceramic core 2 beneath leaving portions 8 40 thereof projecting from the pattern 6. The metal from which the chaplet is constructed must have good resistance to oxidation in mould firing furnace atmospheres. Examples of such metals are, platinum, combinations of nickel, cobalt and chromium 45 alloys, or such dense metal alloys coated with platinum or other metal of superior oxidation resistance. To facilitate the passage of the chaplet 7 onto the material, each chaplet is usually heated to a temperature above the melting point of the pattern 50 material. Each chaplet 7 is made of expanded metal sheet and several examples of expanded metal sheet felt to be suitable are illustrated in Figure 5.
These particular examples of expanded metal sheet are made by Expamet Industrial Products 55 Limited of 16 Caxon Street, London, SW1H 0RA. The expanded metal is made by producing a plurality of slits in a metal sheet and then stretching the sheet to form a mesh. For a given volume of material, a chaplet made of this material affords a more rigid 60 support distributed over a greater area than a single unexpanded piece of material. This enables less material to be used for a given support requirement, a factor of considerable importance when the chaplets are made of a precious metal such as platinum. 65 The expanded metal may be bent in the plane of the surface of the pattern to form a chaplet of 'C' shaped, 'U' shaped, 'V' shaped or other cross-section thereby enabling support to be produced over a greater area with a single chaplet than would otherwise be the case. In a preferred form each chaplet 7 consists of a sheet of expanded metal having cross-sectional dimensions of approximately 0.015" x 0.040" and a length to enable it to project approximately 0.20" out of the wax pattern to enable ready keying with the mould material of the outer mould part. The aper-tured nature of the expanded metal material affords ready access to a greater bulk of the material of the chaplet 7 and this promotes fusion of the chaplet with the poured metal in the casting or pouring step itself.
After the required number of expanded metal chaplets 7 have been inserted in the required positions in the pattern 6, the pattern is dip coated and stuccoed. In this step, an extremely fine ceramic coating, known as a pre-coat, is applied as a slurry directly to the surface of the pattern 6 to reproduce maximum surface smoothness in the casting. The slurry is stuccoed with fine refractory particles and may be made more impermeable to molten metal by the addition of one or even two additional coats. This coated pattern is then surrounded in a block or flask mould by coarser, cheaper and more permeable investment to form the mould. The projecting portions 8 of the chaplets 7 locate in the outer part of the mould 9 so formed (see Figure 3). After the mould material has set and dried the pattern of low melting point material is melted and drained out of the mould which is then heated to a temperature of the order of 1050°C. The molten metal 10 is then poured into the cavity left by the melted pattern. As this molten metal enters the apertures of the expanded metal chaplets, the material of the chaplets 7 is distributed into the mass of the molten material (see Figure 4). After allowing the molten material to solidify and cool, the outer part of the mould is broken away from the mould and the core of the mould is disolved and removed.
Although the embodiment of the invention described above has been described in relation to the block or flask mould process, expanded metal chaplets may also readily be applied to the shell mould process. In such a process, as compared with the above described block mould process, after the application of the pre-coat for the production of maximum surface smoothness in the casting, several coarser coats are applied, also by dipping and stuccoing, in orderto build up a shell strong enough to support the poured metal.
It will be appreciated that the above embodiments have been described by way of example and that many variations are possible within the scope of the invention.
Claims (31)
1. A method of investment casting using an investment casting block mould having a core including the steps of forming a pattern about the core of the mould, inserting the chaplets into the pattern until they engage the core, forming the outer
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GB 2 111 881 A
3
part of the mould about the pattern, removing the pattern, pouring molten metal into the cavity left thereby to produce a casting into which the material of the chaplets is fused, allowing the molten metal to 5 solidify and removing the outer part and core of the block mould.
2. A method of investment casting using an investment casting mould having a core including the steps of forming a pattern about the core of the
10 mould, forming chaplets from sheets of expanded metal, inserting the chaplets into the pattern until they engage the core, forming the outer part of the mould about the pattern, removing the pattern, pouring molten metal into the cavity left thereby to
15 produce a casting into which the material of the expanded metal chaplets is fused, allowing the molten metal to solidify, and removing the outer part and core of the mould.
3. A method as claimed in Claim 1 or 2, in which
20 each chaplet is dimensioned so that a portion of it projects from the wax pattern and subsequently locates in the outer part of the mould.
4. A method as claimed in Claim 1,2 or 3, in which each chaplet is a flat strip of expanded metal.
25
5. A method as claimed in Claim 1,2, or 3, in which each chaplet is bent in the plane of the surface of the pattern.
6. A method as claimed in Claim 5, in which each chaplet is bent to give the chaplet a 'C' shaped cross
30 section.
7. A method as claimed in Claim 5, in which each chaplet is bent to give the chaplet a 'U' shaped cross section.
8. A method as claimed in Claim 5, in which each
35 chaplet is bent to give the chaplet a 'V' shaped cross section.
9. A method as claimed in any preceding claim, in which each chaplet is made of platinum, or combinations of nickel cobalt and chromium alloys,
40 or such dense metal alloys coated with platinum or other metal of superior oxidation resistance.
10. A method as claimed in any preceding claim in which the pattern is made of wax, synthetic plastics or other material having a relatively low
45 melting point.
11. A method as claimed in Claim 2 or any of Claims 3 to 10 when appendant directly or indirectly to Claim 1, in which the outer part of the mould is formed by means of the block or flask mould
50 process.
12. A method as claimed in Claim 2 or any of Claims 3 to 10 when appendant directly or indirectly to Claim 1, in which the outer part of the mould is formed by means of the shell mould process.
55
13. A method as claimed in any preceding claim, in which the core and mould outer part are made of a ceramic material.
14. A method as claimed in any preceding claim, in which each chaplet is heated to a temperature
60 above the melting point of the pattern material to ease its passage through the pattern.
15. A method of investment casting substantially as hereinbefore described with reference to the accompanying drawings.
65
16. An investment casting block mould comprising a core, a mould outer part disposed around and spaced from the core and chaplets extending between the outer part and the core and locating the core within the outer mould part.
17. An investment casting mould comprising a core, a mould outer part disposed around and spaced from the core, and chaplets made of expanded metal extending between the outer part and the core and locating the core within the outer mould part.
18. A mould as claimed in Claim 16 or 17, in which the inner part of each chaplet engages but does not penetrate the core and the outer part of each chaplet locates in the outer part of the mould.
19. A mould as claimed in Claim 16,17 or 18, in which each chaplet is a flat strip of expanded metal.
20. A mould as claimed in Claim 16,17 or 18, in which each chaplet is bent in the plane of the surface of the mould.
21. A mould as claimed in Claim 20, in which each bent chaplet has a 'C' shaped cross section.
22. A mould as claimed in Claim 20, in which each bent chaplet has a 'U' shaped cross section.
23. A mould as claimed in Claim 20, in which each bent chaplet has a 'V' shaped cross section.
24. A mould as claimed in any of Claims 16 to 22, in which each chaplet is made of platinum, or combinations of nickel cobalt and chromium alloys, or such dense metal alloys coated with platinum or other metal of superior oxidation resistance.
25. A mould as claimed in any of Claims 16 to 24, in which the pattern is made of wax, synthetic plastics or other material having a relatively low melting point.
26. A mould as claimed in Claim 17 or any of Claims 18 to 24, when appendant directly or indirectly to Claim 17, in which the outer part of the mould is formed by means of the block or flask mould process.
27. A mould as claimed in Claim 17 or any of Claims 18 to 24 when appendant directly or indirectly to Claim 17, in which the outer part of the mould is formed by means of the shell mould process.
28. A mould as claimed in any of Claims 16 to 27, in which the core and mould outer part are made of a ceramic material.
29. An investing casting mould substantially as hereinbefore described with reference to the accompanying drawings.
30. A casting when made by the method of any of Claims 1 to 15.
31. A casting when made by the mould of any of Claims 16 to 29.
Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1983.
Published by The Patent Office, 25 Southampton Buildings, London, WC2A1AY, from which copies may be obtained.
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Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8137945 | 1981-12-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2111881A true GB2111881A (en) | 1983-07-13 |
Family
ID=10526656
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08235678A Withdrawn GB2111881A (en) | 1981-12-16 | 1982-12-15 | Investment casting process and mould |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0084234A1 (en) |
| GB (1) | GB2111881A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4811778A (en) * | 1987-06-03 | 1989-03-14 | Rolls-Royce Plc | Method of manufacturing a metal article by the lost wax casting process |
| US6095756A (en) * | 1997-03-05 | 2000-08-01 | Mitsubishi Heavy Industries, Ltd. | High-CR precision casting materials and turbine blades |
| US7172012B1 (en) * | 2004-07-14 | 2007-02-06 | United Technologies Corporation | Investment casting |
| CN106002112A (en) * | 2016-05-31 | 2016-10-12 | 西北工业大学 | Turbine blade ceramic core soft core support machining method |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4728258A (en) * | 1985-04-25 | 1988-03-01 | Trw Inc. | Turbine engine component and method of making the same |
| GB8800686D0 (en) * | 1988-01-13 | 1988-02-10 | Rolls Royce Plc | Method of supporting core in mould |
| GB9120161D0 (en) * | 1991-09-20 | 1991-11-06 | Johnson Matthey Plc | New pinning wire products |
| EP1053804A1 (en) * | 1999-05-20 | 2000-11-22 | Asea Brown Boveri AG | Chaplet |
| EP1053805A1 (en) * | 1999-05-20 | 2000-11-22 | Asea Brown Boveri AG | Support element |
| GB0226559D0 (en) | 2002-11-14 | 2002-12-18 | Rolls Royce Plc | Investment moulding process and apparatus |
| US6913064B2 (en) * | 2003-10-15 | 2005-07-05 | United Technologies Corporation | Refractory metal core |
| US20050087319A1 (en) * | 2003-10-16 | 2005-04-28 | Beals James T. | Refractory metal core wall thickness control |
| US7036556B2 (en) * | 2004-02-27 | 2006-05-02 | Oroflex Pin Development Llc | Investment casting pins |
| FR2874186B1 (en) * | 2004-08-12 | 2008-01-25 | Snecma Moteurs Sa | PROCESS FOR THE PRODUCTION BY LOST WAX MOLDING OF PARTS COMPRISING AT LEAST ONE CAVITY. |
| FR2966067B1 (en) | 2010-10-19 | 2017-12-08 | Snecma | INJECTION MOLD FOR WAX MODEL OF TURBINE BLADE WITH ISOSTATIC CORE SUPPORT |
| CN102139355A (en) * | 2011-03-15 | 2011-08-03 | 中核苏阀横店机械有限公司 | Locating chaplet |
| CN104923722B (en) * | 2015-06-24 | 2017-03-22 | 西安航空动力股份有限公司 | Method for controlling hollow guide blade upper edge plate cavity wall thickness |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB926399A (en) * | 1961-05-03 | 1963-05-15 | Howe Sound Co | Method of manufacturing complex air cooled turbine components |
| US3981344A (en) * | 1974-08-21 | 1976-09-21 | United Technologies Corporation | Investment casting mold and process |
| GB2053757B (en) * | 1979-07-19 | 1983-02-23 | Rolls Royce | Lost wax patterns |
| US4283835A (en) * | 1980-04-02 | 1981-08-18 | United Technologies Corporation | Cambered core positioning for injection molding |
-
1982
- 1982-12-13 EP EP82306628A patent/EP0084234A1/en not_active Withdrawn
- 1982-12-15 GB GB08235678A patent/GB2111881A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4811778A (en) * | 1987-06-03 | 1989-03-14 | Rolls-Royce Plc | Method of manufacturing a metal article by the lost wax casting process |
| US6095756A (en) * | 1997-03-05 | 2000-08-01 | Mitsubishi Heavy Industries, Ltd. | High-CR precision casting materials and turbine blades |
| US7172012B1 (en) * | 2004-07-14 | 2007-02-06 | United Technologies Corporation | Investment casting |
| CN106002112A (en) * | 2016-05-31 | 2016-10-12 | 西北工业大学 | Turbine blade ceramic core soft core support machining method |
| CN106002112B (en) * | 2016-05-31 | 2017-11-28 | 西北工业大学 | The soft stud processing methods of turbo blade Tao Xin |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0084234A1 (en) | 1983-07-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |