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WO2019009714A1 - Procédé de moulage pour fabriquer un produit métallique 3d - Google Patents

Procédé de moulage pour fabriquer un produit métallique 3d Download PDF

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Publication number
WO2019009714A1
WO2019009714A1 PCT/NL2018/050435 NL2018050435W WO2019009714A1 WO 2019009714 A1 WO2019009714 A1 WO 2019009714A1 NL 2018050435 W NL2018050435 W NL 2018050435W WO 2019009714 A1 WO2019009714 A1 WO 2019009714A1
Authority
WO
WIPO (PCT)
Prior art keywords
mould
product
sheet
form negative
thermoforming
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.)
Ceased
Application number
PCT/NL2018/050435
Other languages
English (en)
Inventor
Janne Tuomas Kyttanen
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.)
What the Future Food BV
Original Assignee
What the Future Venture Capital WTFVC BV
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 claimed from NL2019403A external-priority patent/NL2019403B1/nl
Application filed by What the Future Venture Capital WTFVC BV filed Critical What the Future Venture Capital WTFVC BV
Priority to US16/624,395 priority Critical patent/US10821498B2/en
Publication of WO2019009714A1 publication Critical patent/WO2019009714A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • 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
    • B22C7/023—Patterns made from expanded plastic materials
    • 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

Definitions

  • the invention is directed to a casting process to make a metal 3D product.
  • Casting is a manufacturing process in which a molten metal material is poured into a mould.
  • the mould has a hollow cavity of the desired shape and the metal is allowed to solidify.
  • the solidified 3D product may be broken out of the mould.
  • Cold setting materials which cure after mixing of two or more components are also used instead of a molten metal.
  • a casting process used on a commercial scale is the so-called investment casting. In this process a wax copy of the 3D product to be made is surrounded with a refractory material. A wax gating system is present which connects the wax copy with the exterior of the refractory material.
  • the ceramic moulds thus obtained are cured and subjected to a burnout step.
  • the wax melts and/or vaporizes and is able to leave the ceramic mould via the gating system leaving a hollow space corresponding to the 3D product.
  • molten metal is poured into the opening of the gating system such that the metal fills the hollow space corresponding to the 3D product. After the metal solidifies the ceramic shell is removed and the metal 3D product is obtained.
  • Such investment casting is a well-known process and has been used in various forms for the last 5000 years.
  • a disadvantage of the known processes is that a wax copy of the 3D product has to be made.
  • the wax copy is difficult to handle because it can be damaged before the wax copy is surrounded by the refractory material.
  • Alternatives for wax have been proposed which are stronger.
  • polystyrene has been suggested as an alternative for wax.
  • a problem with such a material is that the solid polystyrene copy of the 3D product expands when heated in the burnout step. The expanded polystyrene could damage the ceramic mould.
  • GB999316 of 1962 it is suggested to cover the polystyrene copy with a thin layer of wax.
  • the wax would melt before the polystyrene such to leave a space in which the polystyrene can expand before it melts or combusts.
  • polystyrene or other plastic materials have been suggested for some years it appears that wax is still the most used material in the casting processes.
  • JPS 60137546, DE102009033170 and JPH0538550 describe a casting process wherein a form mould is a formed plastic sheet. Such a form mould is stronger and less prone to damage as a wax copy. When products having changing designs have to be made in high numbers such processes are not preferred because they are laborious.
  • the present inventions aims to provide a casting process which can manufacture different designed products in high numbers.
  • moulds may be obtained in a simple and fast method when such moulds are obtained by thermoforming.
  • Thermoforming is a method known from the packaging industry and allows the manufacture of large numbers of moulds in a quick process.
  • a form negative mould of the 3D product comprising of a plastic sheet.
  • the mould is an object comprising of a plastic sheet which surrounds a hollow space at its inner side.
  • the hollow space corresponds with at least the shape of one or more of the 3D products.
  • molten metal is poured into the hollow space.
  • the plastic sheet further defines a gating system. This gating system fluidly connects an opening into which molten metal may be poured in with the hollow spaces corresponding to the 3D products.
  • the hollow space corresponding to the 3D products may be slightly smaller than the 3D products obtained in step (d). This difference in dimensions is caused by the dimensions of the plastic sheet. This plastic sheet will be removed prior to step (c) or in step (c). Thus the space occupied by the plastic sheet will also be filled with molten metal. Some metals may shrink slightly when solidifying. This difference may then be compensated.
  • the form negative mould of the 3D product is suitably comprised of at least two parts, also here referred to as shell parts, which are combined to obtain the mould. Complex designs of the 3D product to be made may require more than 2 shell parts. The use of 2 or more shell parts has been found advantageous because it simplifies the manufacture process of the mould.
  • the form negative mould of the 3D product comprises of a plastic sheet as obtained by thermoforming using a master mould which master mould.
  • This master mould may be obtained by 3D printing or machined making use of for example computer numerical control.
  • the master mould is obtained by 3D printing because this enables one to manufacture different designs without having to make master mould using labourous techniques like machining.
  • 3-D printing technologies will be available to the skilled addressee, printing in a range of materials including plaster (e.g. with the 3-D printer sold under the Registered Trademark "ProJet ® 660 Pro” by 3D systems Inc., USA), thermoplastics, photopolymerised polymers, or thermally-sintered materials.
  • the mould is produced using thermal sintering (preferably by laser) of materials such as that sold under the Registered Trademark Alumide ® , and comprising a powdered composition of polyamide and powdered aluminium.
  • thermal sintering preferably by laser
  • materials such as that sold under the Registered Trademark Alumide ® , and comprising a powdered composition of polyamide and powdered aluminium.
  • the inventors have found that such a process and material produce a master mould that is particularly effective at resisting the temperatures applied in the thermoforming process.
  • the master mould is provided with a number of openings which fluidly connect the side of the master mould facing the form negative mould of the 3D product and its opposite side.
  • the thickness of the master mould is preferably between 0.5 and 5 mm.
  • the holes are typically less than 2 mm in diameter, and preferably less than 1 mm in diameter.
  • the openings allow air to escape through the master mould during the forming process.
  • the master mould is further suitably provided with channels for passage of cooling air. Cooling of the master mould enhances the produced form negative mould of the 3D product to solidy into its desired shape in the master mould.
  • Thermoforming is a manufacturing process where a plastic sheet is heated to a pliable forming temperature and formed to a specific shape in a master mould. The sheet is heated to a high-enough temperature that permits it to be stretched into or onto a mould and cooled to a finished shape.
  • the different shell parts of the form negative mould of the 3D product may be made using the same or different manufacturing processes as here described.
  • Thermoforming is suitably performed using a thermoforming packaging machine.
  • Thermoforming packaging machines are well known. Such machines enables one to prepare numerous moulds in a continuous process starting from a roll of sheet or from an extruder providing a sheet.
  • Such a thermoforming packaging machine may comprise of one or two thermoforming stations, a sealing station and a cutting station.
  • the thermoforming packaging machine may comprise of one or two thermoforming stations, a sealing station and a cutting station.
  • the thermoforming packaging machine may comprise of one or two thermoforming stations, a sealing station and a cutting station.
  • thermoforming packaging machine comprises of one or two thermoforming stations, a sealing station and a cutting station and wherein the in a thermoforming station a formed intermediate sheet is obtained, wherein in the sealing station this formed intermediate sheet is combined with a planar sheet or with another formed intermediate sheet obtained in the optional second thermoforming station to obtained connected form negative moulds of the 3D product and wherein in the cutting station the form negative moulds of the 3D product are cut from the connected form negative moulds of the 3D product.
  • a form negative mould of the 3D product is suitably made comprised of two formed plastic sheets or the mould is comprised of one formed plastic sheet and one planar sheet.
  • the plastic sheet may be any type of plastic and especially plastics suitable for injection moulding, vacuum forming or thermoforming.
  • the material for the plastic sheet is preferably strong at a minimum sheet thickness.
  • the plastic sheet should be easy to remove before or in step (c).
  • the plastic is suitably a thermoplastic polymer.
  • thermoplastic polymers examples include polyethylene, polypropylene,
  • the thickness of the sheet may vary from 50 microns to even 5 mm, wherein the lower part of the range may be used to make smaller products and the upper end of the range may be used to make larger products. For example, for making products having a maximum dimension of less than 50 cm the thickness of the sheet may vary between 50 and 200 microns.
  • step (b) a layer of refractory material is applied on the exterior of the plastic sheet of the mould.
  • This may be performed in the same manner as known for applying a layer of refractory around a wax copy as known from the prior art.
  • the ceramic mould may be produced by repeating a series of steps— coating, stuccoing, and hardening— until a desired thickness is achieved.
  • Coating involves dipping the form negative mould of the 3D product into a slurry of fine refractory material and then draining to create a uniform surface coating.
  • Fine materials are used in this first step, also called a prime coat, to preserve fine details as may be present at the exterior of the form negative mould of the 3D product.
  • refractory materials are silica, zircon, various aluminium silicates such as mullite, and alumina. Zircon-based refractories may be used for the prime coat.
  • the form negative mould of the 3D product may be removed from the ceramic mould. This may be performed by heating the ceramic mould to a temperature wherein the plastic become fluid such that it can flow out of the ceramic mould via the gating system, for example under the influence of gravity.
  • the plastic mould may also be removed by carbonization of the plastic mould, for example during the below described burn-out step. Because the plastic sheet material is relatively thin significantly less stress is expected when the form negative mould of the 3D product is removed at an elevated temperature.
  • the plastic form negative mould of the 3D product is removed from the ceramic mould by dissolving the plastic in a suitable solvent.
  • a suitable solvent will depend on the polymer used for the plastic form negative mould of the 3D product.
  • solvents suitable in combination with for example polystyrene
  • ketones such as dimethylketon, methyl ethyl keton, methyl isobutyl keton optionally in combination with small amounts of a lower alcohol co-solvent.
  • lower alcohols examples include methanol, ethanol and propanol.
  • the temperatures during dissolution of the plastic may be increased to above ambient to enhance the dissolution.
  • Dissolving plastics may be performed according to well established methods as for example described in Beth A.Miller-Chou et al., A review of polymer dissolution, Prog. Polym.Sci.28 (2003) 1223-1270.
  • the hollow space which remains in the ceramic mould is the space left by the thus removed form negative mould of the 3D product.
  • the ceramic mould may then be subjected to a burnout step wherein the temperature is raised to between 850 and 1100 °C. At these temperatures the plastic form negative mould of the 3D product, if still present, will typically be removed by carbonization of the plastic material.
  • the plastic form negative mould of the 3D product is not removed and is as such present when molten metal is poured into the hollow space of the mould.
  • the layer of the formed plastic sheet will then melt into the metal in step (c).
  • the volume of the plastic form negative mould of the 3D product is relatively small relative to the total volume of the 3D product relatively small amounts of plastic will melt into the metal. For some applications this may not be critical resulting in an even more simplified process.
  • step (c) molten metal is poured into the hollow space of the ceramic mould.
  • a gating system fluidly connects the opening in the ceramic mould with the hollow space in the ceramic mould in which the 3D product is formed.
  • the metals may be those typically used in investment casting processes. Once the molten metal is poured into the hollow space it is allowed to solidify.
  • Step (c) may be performed in any manner which is known for casting, for example it can also be performed as counter-gravity casting and vacuum casting.
  • Figure 1 shows a thermoforming packaging apparatus 1 having two rolls 2 of polystyrene sheet 3.
  • the polystyrene sheets 3 travel in the direction of the arrow 4.
  • an upper form negative mould (master mould) 6 of the 3D product forms the sheet 3 into a formed shell part 7,8.
  • a lower form negative mould (master mould) 9 of the 3D product forms the sheet 3 into a formed shell part 10, 11.
  • shell part 8 is sealed to shell part 11 and cut off to obtain a form negative mould 12 of the 3D product as shown in Figure 2.
  • shell part 7 is sealed to shell part 10 and also cut off to obtain a next form negative mould of the 3D product. This is repeated until a desired number of form negative moulds are obtained.
  • the thus obtained form negative mould 12 is made up of a
  • polystyrene sheet 13 and a hollow space 14 at its interior side.
  • the hollow space 14 corresponds with the shape the 3D product 16 to be obtained.
  • a gating system 15 is shown and a part 17 where the two sheets 3 are sealed.
  • Figure 3 shows the view AA' of Figure 2 where the reference numbers have the same meaning.
  • Figure 4 shows form negative mould 12 with a layer of refractory 18 placed in a tub 19 filled with sand 20. Molten metal 21 may be poured into the opening 22 of gating system 15.
  • thermoforming apparatus 30 After cutting away the metal part 24 as formed in the gating system 15 the final metal 3D product 16 is obtained as shown in Figure Figure 7 shows a thermoforming apparatus 30.
  • a formed shell part is combined with a planar shell part.
  • the process runs in the direction of arrow 29.
  • a formed shell part 31 is obtained by thermoforming a sheet 32 of polystyrene drawn from roll 33 using master mould 6. This process is advantageous because it does not require to manufacture an upper and lower form negative (master) mould of Figure 1.
  • the formed shell part 31 is combined with a planar polystyrene sheet 38 as drawn from roll 39.
  • shell part 31a is sealed to planar sheet 38 and cut off to obtain a form negative mould. Subsequently shell part 31 is combined with planar sheet 38 and also cut off to obtain a next form negative mould of the 3D product.
  • the form negative moulds may be used as shown in Figures 4-6 to make a metal 3D product, i.e. a metal copy of the 3D object 34.
  • Figure 7 a continuous vacuum forming apparatus is illustrated.
  • a stand-alone vacuum table When only one or a small number of copies of the 3D object is desired one can make the formed shell part 31 on a piece by piece manner using for example a stand-alone vacuum table.
  • Figure 8 shows a side view of a transparent form negative mould 40 having a plastic sheet 41 which defines at its inner side a hollow space 42 corresponding with the shape of three 3D products.
  • the sheet 41 also defines a gating system 43 which allows molten metal to flow from opening 44 to all three hollow spaces 42.
  • Such a mould 40 may be prepared by the apparatus of Figure 1 or Figure 7.
  • Figures 9 and 10 show how the formed shell part 31 of Figure 7 may also be combined with a second formed shell part 45 to obtain a form negative mould of the 3D product 46.
  • the inner side of this form negative mould 46 is a hollow space 48 corresponding with the shape of the final 3D product one wishes to obtain by the casting process.
  • Second formed part 45 may be obtained in a continuous thermoforming packaging apparatus of Figure 1. Also a gating system 48 is shown.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

La présente invention concerne un procédé de moulage pour fabriquer un produit métallique 3D par conduite des étapes suivantes, (a) fourniture d'un moule négatif de forme du produit 3D comprenant une feuille de plastique, ladite feuille définissant au niveau de son côté interne un espace creux correspondant à au moins la forme d'un ou plusieurs des produits 3D par thermoformage au moyen d'un moule maître, (b) application d'une couche de matériau réfractaire sur l'extérieur de la feuille en plastique du moule pour obtenir un moule en céramique comportant un espace creux, (c) coulée du métal fondu dans l'espace creux du moule en céramique et attente que le métal solidifie, et (d) retrait de la couche de matériau réfractaire pour obtenir le produit métallique 3D.
PCT/NL2018/050435 2017-07-05 2018-07-04 Procédé de moulage pour fabriquer un produit métallique 3d Ceased WO2019009714A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US16/624,395 US10821498B2 (en) 2017-07-05 2018-07-04 Casting process to make a metal 3D product

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201762528578P 2017-07-05 2017-07-05
US62/528,578 2017-07-05
NL2019403 2017-08-08
NL2019403A NL2019403B1 (en) 2017-07-05 2017-08-08 Casting process to make a metal 3d product

Publications (1)

Publication Number Publication Date
WO2019009714A1 true WO2019009714A1 (fr) 2019-01-10

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Family Applications (1)

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PCT/NL2018/050435 Ceased WO2019009714A1 (fr) 2017-07-05 2018-07-04 Procédé de moulage pour fabriquer un produit métallique 3d

Country Status (1)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL2022372B1 (en) * 2018-12-17 2020-07-03 What The Future Venture Capital Wtfvc B V Process for producing a cured 3d product

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB999316A (en) 1962-10-01 1965-07-21 Howe Sound Co Improvements in or relating to heat-disposable foundry patterns
JPS60137546A (ja) 1983-12-27 1985-07-22 Toyota Motor Corp 鋳造用中空消失性模型の作製方法
JPH0538550A (ja) 1991-08-03 1993-02-19 Asahi Tec Corp 消失模型
DE102009033170A1 (de) 2009-07-13 2011-01-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verlorenes Gießmodell und Gießverfahren

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB999316A (en) 1962-10-01 1965-07-21 Howe Sound Co Improvements in or relating to heat-disposable foundry patterns
JPS60137546A (ja) 1983-12-27 1985-07-22 Toyota Motor Corp 鋳造用中空消失性模型の作製方法
JPH0538550A (ja) 1991-08-03 1993-02-19 Asahi Tec Corp 消失模型
DE102009033170A1 (de) 2009-07-13 2011-01-27 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verlorenes Gießmodell und Gießverfahren

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
BETH A.MILLER-CHOU ET AL.: "A review of polymer dissolution", PROG. POLYM.SCI., vol. 28, 2003, pages 1223 - 1270

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL2022372B1 (en) * 2018-12-17 2020-07-03 What The Future Venture Capital Wtfvc B V Process for producing a cured 3d product
US11305458B2 (en) 2018-12-17 2022-04-19 What The Future Venture Capital (Wtfvc) B.V. Process for producing a cured 3D product

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