US3717914A - Reusable mandrel for structures having zero draft or re-entrant geometries - Google Patents

Reusable mandrel for structures having zero draft or re-entrant geometries Download PDF

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Publication number
US3717914A
US3717914A US00156191A US3717914DA US3717914A US 3717914 A US3717914 A US 3717914A US 00156191 A US00156191 A US 00156191A US 3717914D A US3717914D A US 3717914DA US 3717914 A US3717914 A US 3717914A
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US
United States
Prior art keywords
mandrel
alloy
structures
coated
polyimide
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 - Lifetime
Application number
US00156191A
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English (en)
Inventor
R Baird
T Everett
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.)
Praxair ST Technology Inc
Original Assignee
Union Carbide Corp
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
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Publication of US3717914A publication Critical patent/US3717914A/en
Assigned to UNION CARBIDE COATINGS SERVICE TECHNOLOGY CORPORATION reassignment UNION CARBIDE COATINGS SERVICE TECHNOLOGY CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNION CARBIDE COATINGS SERVICE CORPORATION
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
    • 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
    • B22C9/101—Permanent cores
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/18—After-treatment
    • C23C4/185—Separation of the coating from the substrate
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12556—Organic component
    • Y10T428/12569—Synthetic resin
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12778—Alternative base metals from diverse categories
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31678—Of metal
    • Y10T428/31681—Next to polyester, polyamide or polyimide [e.g., alkyd, glue, or nylon, etc.]

Definitions

  • the mandrel consists essentially of a high-melting-point base mandrel, such as aluminum, having a low-meltingpoint metallic alloy undercoat and a polyimide overcoat.
  • Another technique employed by the casting industry is to prepare low-melting-point mandrels for use in the fabrication of high-melting-point structures.
  • the cast unit upon completion, can be heated to a temperature below that of the structure but above that of the mandrel so that the latter can be removed in the liquid phase.
  • This type mandrel in addition to having the disadvantage of being non-reusable, is also limited to casting'applications that do not exceed the melting point of the mandrel and to the casting of only high-melting point structures.
  • the primary purpose of this invention is to overcome the limitation inherent in conventional type mandrels by providing a new removable type mandrel that will be admirably suited for use in the casting and plasmadeposition of various structures having as low as zero draft or re-entrant geometries.
  • a mandrel is composed by coating a low-melting-point metallic alloy on a high-melting-point base mandrel and then overcoating the alloy with a polyimide layer.
  • the undercoated alloy layer has to be sufficiently thick so that after a structure is coated or sprayed onto or into the mandrel, the assembly can be heated to the melting point of the alloy so that it can be removed in the liquid state leav ing a space between the structure and the mandrel sufficient to allow the mandrel to be easily removed.
  • the base mandrel can be cast or otherwise fabricated using a high-melting-point material selected from at least one of the groups consisting of aluminum, brass, steel, and copper.
  • the metallic alloy coating should have a lowmelting point with reference to the'base mandrel, and also with reference to the structure to be cast or plasma deposited. The thickness of this metallic alloy coating is variable and depends on the configuration, material and size of the structure being cast.
  • a thickness between about one-sixteenth inch and about l inch is sufficient with a thickness about one-eighth inch being preferable for general applications.
  • Metallic alloys having a melting point below 300 C. are generally suitable for this application. However, the selected base mandrel material and structure material dictate the limitations on the characteristics required of this metallic allow coating. Metallic alloys such as bismuth, lead, tin, cadmium, indium, and antimony in any and all proportions are suitable for use in this invention.
  • the primary purpose for applying an overcoat on the alloy layer is to substantially eliminate any reaction between the structure to be cast or plasma deposited and the alloy layer. Therefore this overcoating need only be applied to the portion of the coated mandrel that the structure will contact.
  • this outer layer must have a higher melting point than the alloy, be easily separable from the cast or plasma deposited structure: and be non-reactive with the deposited structure.
  • the exact thickness of this outer coating is not critical but a layer of between about 0.002 inch and about 0.010 inch is deemed sufficient for most applications.
  • Polyimide coatings are admirably suited for this overcoat layer. Polyimides are a relatively recently developed type of polymer with especially good resistance to heat deterioration.
  • a typical example of a polyimide is that derived from pyromellitic dianhydride and an aromatic diamine and having the following basic structure unit: [-(CO), C,H,(CO),NC,H OC,H,-]n.
  • the actual polymer however, has a more complex structure due to cross linking.
  • the preferred method for implementing this invention is to initially fabricate a base mandrel from a highmelting-point material such as aluminum.
  • the contour of a male or female type mandrel in addition to substantially conforming to the configuration of the desired structure, has to be produced with radial dimensions smaller or larger, respectively, than the structure so as to allow for a dual coating buildup. Usually a one-fourth to one-half inch dimension discrepancy is adequate for this purpose.
  • An alloy having a melting point below about 700 C., preferably about 250 C., is then deposited on the mandrel by any conventional technique such as by spraying, brushing, casting, painting or the like.
  • the thickness of this coated layer is somewhat variable and depends primarily on the complexity of the structure desired, that is, the draft angle or any other re-entrant geometries such structure has.
  • the purpose of this layer is to provide a certain dimensional buildup on the mandrel which can then be easily removed in a liquid state at an elevated temperature after the desired structure is cast or plasma-deposited thereon. The space created between the mandrel and the structure by such alloy removal, will then be sufficient to allow the mandrel to be manipulated and then easily removed thereby leaving a free standing body.
  • a metallic alloy layer of between about one-sixteenth inch and about 1 inch is usually sufficient for most complex structures.
  • At least one locking type groove or projection may be designed into the base mandrel so as to prevent the base mandrel from sliding out of, or otherwise being removed from, the coated metallic alloy layer prior to the latter being removed in the -liquid state.
  • the metallic alloy layer will usually require a machining operation to conform its surface to the contour of the desired structure to be produced.
  • complex curvilinear structures can be fabricated using this mandrelof a neutral type plastic composition, having a curving temperature below the melting temperature of the alloy coating, is deposited by any conventional technique on the metallic alloy layer.
  • This outer layer need only be applied to that portion of the metallic coated mandrel that will be contacted by the structure to be cast or plasma-sprayed thereon.
  • This outer coating need only be between about 0.002 inch and about 0.010 inch thick, and be capable of being easily removed from the structures formed.
  • a 0.005 inch layer of DuPont Pyralin Type 5081 polyimide (15.2 percent gravimetric solids, 50-70 poises viscosity) will be sufficient to prevent chemical and/or physical interaction between an alloy such as 4 percent Bismuth, 55.5 percent Lead, 40.5 percent Tin (commercially available as Cerro 400-1 alloy) and a plasma-deposited material such as beryllium.
  • the cured polyimide coating can be given a moderate grit blast to roughen the surface. A moderate roughening of the surface. may be described as one of 120-200 micron inch RMS surface roughness.
  • the fully cured dual coated mandrel is then ready for use in casting or plasma-deposition application.
  • the unit is placed in a heated environment where the temperature is elevated above the melting point of e the alloy undercoat.
  • the liquid state alloy then flows from the unit leaving a space between the mandrel and the film adhering structure thereby allowing the mandrel to be easily withdrawn.
  • the neutral type polyimide film can then be peeled from the structure leaving a free standing body.
  • EXAMPLE 1 An aluminum base mandrel as shown in the drawing was coated with a 4 percent Bismuth, 55 .5 percent Lead, 40.5 percent Tin alloy (commercially available as Cerro Type 400-1 alloy) having a melting point range of 170 to 198C. The coated mandrel was machine finished leaving a smooth alloy layer of about one-fourth inch thick on the aluminum base. The surface of the coated mandrel was overcoated with a Du- Pont Pyralin" Type 5081 polyimide precursor solution, 15.2 percent Gravimetric Solids, 50-70 poises viscosity, (commercially available as DuPont Pyralin 5081 polyimide) using an air brush spraying technique.
  • a Du- Pont Pyralin Type 5081 polyimide precursor solution, 15.2 percent Gravimetric Solids, 50-70 poises viscosity, (commercially available as DuPont Pyralin 5081 polyimide) using an air brush spraying technique.
  • a layer of approximately 0.001 inch thick was applied and then the N-Methyl Pyrrolidone and xylene solvent in the coating was extracted by oven heating the coated mandrel to approximately C. for 15 minutes. This procedure was repeated until a 0.004 inch layer was built up whereupon the coated mandrel was cured at an elevated temperature of C. for 16 hours.
  • the coated cured mandrel was then given a light grit blast of aluminum oxide to roughen the surface thereof so as to provide a better adhering surface for a plasma deposition of beryllium.
  • the roughened surface coated mandrel as shown in the drawing was plasma-sprayed with beryllium using the following:
  • Powder Lot Beryllium (commercially available as Brush V-l684-P) Powder Size 325 Tyler mesh size and finer Non-transfer-Arc Torch Union Carbide s AT9 model Electrode Gas 60 CPR Argon Powder Carrier Gas 80 CFH Argon and 40 CFH Argon 15% Hydrogen Shield Not used Current amps.
  • EXAMPLE II A 13 UNC threaded rod, measuring one-half inch in diameter and 24 inches long, was coated with 1.0 inch layer of Cerro Alloy 400-1 as in Example 1, for a length of 19 inches. The surface of the Cerro layer was machined to a smooth finish yielding a final rod diameter of 1.92 inches. The smooth surface was then coated with a 0.005 inch multilayer of DuPont Pyralin 5081 polyimide precursor solution, as described in Example 1, and followed thereafter by a light vapor blast of aluminum oxide to roughen the surface so as to make the surface amenable for a plasma-deposition of beryllium.
  • the polyimide coated surface was plasma-sprayed with beryllium using the following:
  • the coated mandrel was placed in an oven and heated to 210 C.
  • a mandrel comprising a base material having a melting temperature above at least 650 C., a first coated metallic alloy layer having a melting temperature below 700 C. and lower than the melting temperature of said base material, and at least a second coated layer of a polyimide material.
  • said base material is selected from at least one of the: groups'consisting of aluminum, brass, steel, and copper.
  • said metallic alloy layer is selected from at least one of the groups consisting of bismuth, lead, tin, cadmium, indium and antimony.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Laminated Bodies (AREA)
  • Mold Materials And Core Materials (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
US00156191A 1971-06-24 1971-06-24 Reusable mandrel for structures having zero draft or re-entrant geometries Expired - Lifetime US3717914A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US15619171A 1971-06-24 1971-06-24

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US3717914A true US3717914A (en) 1973-02-27

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Family Applications (1)

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Country Status (6)

Country Link
US (1) US3717914A (enExample)
JP (1) JPS5112282B1 (enExample)
CA (1) CA971728A (enExample)
CH (1) CH557706A (enExample)
FR (1) FR2143461B1 (enExample)
GB (1) GB1387300A (enExample)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3864150A (en) * 1971-06-24 1975-02-04 Union Carbide Corp Reusable mandrel for structures having zero draft or re-entrant geometries
US4529615A (en) * 1982-10-11 1985-07-16 Ceskoslovenska Akademie Ved Method of producing self-supporting constructional elements
WO1985005173A1 (en) * 1984-05-02 1985-11-21 General Electric Company Wear resistant gun barrel and method of forming
US5176866A (en) * 1989-02-28 1993-01-05 Asahi Kasei Kogyo Kabushiki Kaisha Process for producing a resin product having a bent hollow portion and a core usable for the same process
US5234636A (en) * 1989-09-29 1993-08-10 3D Systems, Inc. Methods of coating stereolithographic parts
US5847357A (en) * 1997-08-25 1998-12-08 General Electric Company Laser-assisted material spray processing
US6036470A (en) * 1996-03-29 2000-03-14 Basso, Jr.; Robert J. Mandrel for producing composite tubular parts

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0055542A1 (en) * 1980-12-16 1982-07-07 The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Improvements in or relating to the bulk production of alloys by deposition from the vapour phase and apparatus thereof
JPS63106573A (ja) * 1986-10-23 1988-05-11 Chino Corp 測定回路
DE3935255A1 (de) * 1988-11-07 1990-05-10 Westinghouse Electric Corp Verfahren zum herstellen eines spritzauftrags mit hilfe eines verbesserten lichtbogen-spritzgeraets

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1946451A (en) * 1931-04-22 1934-02-06 Ass Elect Ind Production of metal castings

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1946451A (en) * 1931-04-22 1934-02-06 Ass Elect Ind Production of metal castings

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3864150A (en) * 1971-06-24 1975-02-04 Union Carbide Corp Reusable mandrel for structures having zero draft or re-entrant geometries
US4529615A (en) * 1982-10-11 1985-07-16 Ceskoslovenska Akademie Ved Method of producing self-supporting constructional elements
WO1985005173A1 (en) * 1984-05-02 1985-11-21 General Electric Company Wear resistant gun barrel and method of forming
US4577431A (en) * 1984-05-02 1986-03-25 General Electric Company Wear resistant gun barrel and method of forming
EP0339692A3 (en) * 1984-05-02 1990-01-31 General Electric Company Method of forming a wear resistant gun barrel
US5176866A (en) * 1989-02-28 1993-01-05 Asahi Kasei Kogyo Kabushiki Kaisha Process for producing a resin product having a bent hollow portion and a core usable for the same process
US5234636A (en) * 1989-09-29 1993-08-10 3D Systems, Inc. Methods of coating stereolithographic parts
US6036470A (en) * 1996-03-29 2000-03-14 Basso, Jr.; Robert J. Mandrel for producing composite tubular parts
US5847357A (en) * 1997-08-25 1998-12-08 General Electric Company Laser-assisted material spray processing

Also Published As

Publication number Publication date
DE2230516A1 (de) 1972-12-28
FR2143461B1 (enExample) 1977-12-23
GB1387300A (en) 1975-03-12
CA971728A (en) 1975-07-29
DE2230516B2 (de) 1976-02-05
JPS5112282B1 (enExample) 1976-04-17
FR2143461A1 (enExample) 1973-02-02
CH557706A (fr) 1975-01-15

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Owner name: MORGAN GUARANTY TRUST COMPANY OF NEW YORK, AND MOR

Free format text: MORTGAGE;ASSIGNORS:UNION CARBIDE CORPORATION, A CORP.,;STP CORPORATION, A CORP. OF DE.,;UNION CARBIDE AGRICULTURAL PRODUCTS CO., INC., A CORP. OF PA.,;AND OTHERS;REEL/FRAME:004547/0001

Effective date: 19860106

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Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:MORGAN BANK (DELAWARE) AS COLLATERAL AGENT;REEL/FRAME:004665/0131

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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNION CARBIDE COATINGS SERVICE CORPORATION;REEL/FRAME:005240/0883

Effective date: 19900102