US20070057398A1 - Process for producing a three dimensional object from particles, as well as product produced thereby - Google Patents

Process for producing a three dimensional object from particles, as well as product produced thereby Download PDF

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Publication number
US20070057398A1
US20070057398A1 US11/414,573 US41457306A US2007057398A1 US 20070057398 A1 US20070057398 A1 US 20070057398A1 US 41457306 A US41457306 A US 41457306A US 2007057398 A1 US2007057398 A1 US 2007057398A1
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United States
Prior art keywords
casting
particles
water
dimensional object
layer
Prior art date
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Abandoned
Application number
US11/414,573
Inventor
Jialin Shen
Zheng Xu
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Mercedes Benz Group AG
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DaimlerChrysler AG
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Filing date
Publication date
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Assigned to DAIMLERCHRYSLER AG reassignment DAIMLERCHRYSLER AG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SHEN, JAILIN, XU, ZHENG
Publication of US20070057398A1 publication Critical patent/US20070057398A1/en
Assigned to DAIMLER AG reassignment DAIMLER AG CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: DAIMLERCHRYSLER AG
Abandoned legal-status Critical Current

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Classifications

    • 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
    • B22C9/105—Salt cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/165—Processes of additive manufacturing using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the invention concerns a process for producing a three dimensional object from particles, as well as a object produced thereby.
  • a generic process of this type is known for example from WO 2004/112988A2.
  • the known processes for producing a three dimensional object from particles are increasingly employed for manufacture of casting molds and casting cores.
  • the casting shape is built up of sand particles, which are joined by means of binder materials.
  • binder materials Conventionally, organic binders are employed. These however decompose during casting due to the heat, whereby the quality of the produced component can be deteriorated.
  • WO 2004/112988A2 it is proposed in WO 2004/112988A2 to join the sand particles with a salt crystal binder material and/or protein binder material.
  • the task of the present invention is comprised in providing an alternative layer-building type process for producing a three-dimensional object, as well as a therewith produced object, which achieves sufficient cast strength, without causing unacceptable deterioration in quality due to off-gassing of binder material during casting.
  • particles which are comprised of a mono- or polyvalent, water and/or alcohol soluble metal salt.
  • the inventive process for production of a three dimensional object includes the following steps:
  • particles which are employed, which are comprised of at least one mono- or polyvalent, water and/or alcohol soluble metal salt.
  • liquid spray herein includes not only one or more continuous or interrupted streams, but rather also individual droplets.
  • the water and/or alcohol solubility of the entire particle offers the advantage, that the diffusion of solvent into the surrounding particle bed is reduced or even completely prevented, whereby a substantially sharper border or delineation of the sprayed and unsprayed areas result, and therewith the time and effort invested in the subsequent follow-up processing can be substantially reduced.
  • At least one metal salt includes crystal water and/or at least one metal salt exhibits condensable anions.
  • Metal salts with crystal water are characterized by good water solubility, for example, NaCl, CuSO 4 , or Al 2 (SO 4 ) 3 .
  • Metal salts with condensable anions are characterized by increased brown stability, for example, NaAl (H 2 PO 4 ) 3 , K 2 SiO 3 , Na 2 SiO 3 , Na 2 (HPO 4 ) or Na 3 (HPO 4 ).
  • brown stability for example, NaAl (H 2 PO 4 ) 3 , K 2 SiO 3 , Na 2 SiO 3 , Na 2 (HPO 4 ) or Na 3 (HPO 4 ).
  • the condensation reaction can be accelerated by the presence of oxides (for example, CuO, Cu 2 O, Al 2 O 3 , MgO) or hydroxides (for example Al(OH) 3 ).
  • oxides for example, CuO, Cu 2 O, Al 2 O 3 , MgO
  • hydroxides for example Al(OH) 3 .
  • Na 2 (HPO 4 ) or Na 3 (HPO 4 ) are water and alcohol soluble.
  • additives for modifying the surface tension of the melt of the particles for example, calcium phosphate salts, which increase the surface tension of an aluminum melt and thereby ensure a smooth surface of the cast part.
  • An object made of particles joined together which is produced by means of the inventive process, is particularly suited for employment as cast mold or cast core or also as tool or insert for plastic or ceramic mold shaping.
  • cast cores or inserts can be easily disrupted and thereafter removed by spraying with their solvent.
  • a casting mold was built up by spraying with water as a solvent in accordance with a convention 3D printing process.
  • the thickness of the individual print layers was approximately 125 ⁇ m.
  • the casting mold had a green stability of approximately 0.75 MPa. It was heated for approximately two hours at 400° C. and exhibited thereafter a brown stability of 0.62 MPa. The finish processing time and effort was minimal. A simple blowing off of loose particle materials with weak compressed air was sufficient.
  • the test of the casting mold tempered to room temperature with an A356 aluminum alloy casting material at a casting temperature of 730° provided a good casting result with good surface quality.
  • the mold itself was easily removed by dissolving in water for a short time.
  • a casting core was built up by spraying with water as solvent according to a conventional 3D printing process.
  • the powder mixture had a particle diameter of approximately 300-400 ⁇ m.
  • the thickness of the individual print layers was approximately 125 ⁇ m.
  • the casting core had a green stability of approximately 3 MPa. It was heated for approximately two hours at 400° C. and exhibited thereafter a brown stability of 2.5 MPa. This suffices for employment as casting core. The finishing effort was minimal. A simple blowing off of the loose particle material with a compressed air strain was sufficient.
  • the invention is not limited to only the above-described illustrative embodiments, but rather can be broadly applied.
  • the surface quality could be further improved by the addition of supplemental surface modifiers.

Abstract

Generative processes for production of a three dimensional object comprised of particles are increasingly employed in the manufacture of casting molds and casting cores. Therein the casting mold is constituted of sand particles, which are joined using a binder material. The task of the present invention is comprised therein, of providing an alternative layer building-up process for production of a three dimensional object, which achieves sufficient casting stability, without suffering intolerable quality degradation due to evolution of off-gases from binder material during casting. This task is solved by a process employing particles, which are comprised of a mono- or polyvalent, water and/or alcohol soluble metals salt.

Description

    CROSS-REFERENCE TO RELATED APPLICATION
  • This application claims the priority under 35 U.S.C. § 119 of German patent application DE 10 2005 019 699.3, filed on Apr. 28, 2005.
    • BACKGROUND OF THE INVENTION
  • 1. Field of the Invention
  • The invention concerns a process for producing a three dimensional object from particles, as well as a object produced thereby. A generic process of this type is known for example from WO 2004/112988A2.
  • 2. Description of Related Art
  • Generally, the known processes for producing a three dimensional object from particles are increasingly employed for manufacture of casting molds and casting cores. Therein the casting shape is built up of sand particles, which are joined by means of binder materials. Conventionally, organic binders are employed. These however decompose during casting due to the heat, whereby the quality of the produced component can be deteriorated. Thus, it is proposed in WO 2004/112988A2 to join the sand particles with a salt crystal binder material and/or protein binder material.
    • SUMMARY OF THE INVENTION
  • The task of the present invention is comprised in providing an alternative layer-building type process for producing a three-dimensional object, as well as a therewith produced object, which achieves sufficient cast strength, without causing unacceptable deterioration in quality due to off-gassing of binder material during casting.
  • This task is solved by the use of particles, which are comprised of a mono- or polyvalent, water and/or alcohol soluble metal salt.
  • Therein the inventive process for production of a three dimensional object includes the following steps:
  • application of a layer of particles upon a target surface,
  • spraying a selected part of the layer, corresponding to a cross section of the object, with a stream of liquid, which contains water and/or alcohol, so that the particles are joined in the selected part,
  • repeating the steps of application and radiation for a number of layers, such that the adjacent layers join in order to form the object,
  • wherein particles are employed, which are comprised of at least one mono- or polyvalent, water and/or alcohol soluble metal salt.
  • The term “liquid spray” herein includes not only one or more continuous or interrupted streams, but rather also individual droplets.
  • In the inventive process, in contrast to WO 2004/112988A2, sand particles, which there represent the essential structure forming element, are completely dispensed with. Surprisingly, it has been found that particles of mono- or poly-valent, water and/or alcohol and soluble metal salts, subsequent to appropriate spraying, already have a structural rigidity sufficient to meet the requirements for a number of casting applications.
  • Beyond this, the water and/or alcohol solubility of the entire particle, in contrast to the corresponding solubility of essentially only a small binder component, offers the advantage, that the diffusion of solvent into the surrounding particle bed is reduced or even completely prevented, whereby a substantially sharper border or delineation of the sprayed and unsprayed areas result, and therewith the time and effort invested in the subsequent follow-up processing can be substantially reduced.
  • Advantageous to the invention is the employment of lower alcohols (chain length ≦4), since they are simpler to work with, and in particular ethanol due to its better environmental compatibility.
  • According to an advantageous embodiment of the inventive process, at least one metal salt includes crystal water and/or at least one metal salt exhibits condensable anions.
  • Metal salts with crystal water are characterized by good water solubility, for example, NaCl, CuSO4, or Al2 (SO4)3.
  • Metal salts with condensable anions (for example with OH— or ethanol-groups) are characterized by increased brown stability, for example, NaAl (H2PO4)3, K2SiO3, Na2SiO3, Na2(HPO4) or Na3(HPO4). First, they absorb the solvent and show a good green stability. Upon warming, a condensation reaction occurs, of which the reaction products could cause severe defects or gas inclusions during casting. Thus—just as in the case of metal salts with crystal water—first, a removal of the solvent by heating is necessary, from which the brown body results.
  • The condensation reaction can be accelerated by the presence of oxides (for example, CuO, Cu2O, Al2O3, MgO) or hydroxides (for example Al(OH)3). Na2(HPO4) or Na3(HPO4) are water and alcohol soluble.
  • It is advantageous to include additives for modifying the surface tension of the melt of the particles, for example, calcium phosphate salts, which increase the surface tension of an aluminum melt and thereby ensure a smooth surface of the cast part.
  • An object made of particles joined together, which is produced by means of the inventive process, is particularly suited for employment as cast mold or cast core or also as tool or insert for plastic or ceramic mold shaping.
  • In particular, due to their water and/or alcohol solubility, cast cores or inserts can be easily disrupted and thereafter removed by spraying with their solvent.
    • DETAILED DESCRIPTION OF THE INVENTION
  • In the following the inventive process and the therewith produced object will be described in greater detail on the basis of two illustrative embodiments:
  • According to a first illustrative embodiment, in a conventional 3D printing process using a mixture of NaCl (65 wt. %) and MgSO4 (35 wt. %) particles with a diameter between 30 and 100 μm, a casting mold was built up by spraying with water as a solvent in accordance with a convention 3D printing process. The thickness of the individual print layers was approximately 125 μm.
  • The casting mold had a green stability of approximately 0.75 MPa. It was heated for approximately two hours at 400° C. and exhibited thereafter a brown stability of 0.62 MPa. The finish processing time and effort was minimal. A simple blowing off of loose particle materials with weak compressed air was sufficient.
  • The test of the casting mold tempered to room temperature with an A356 aluminum alloy casting material at a casting temperature of 730° provided a good casting result with good surface quality. The mold itself was easily removed by dissolving in water for a short time.
  • According to a second illustrative embodiment, in a conventional 3D printing process, using a mixture of Al (H2PO4)3 27 wt. % (condensable water soluble salt); MgSO4 (15.7 wt. %) (water soluble salt with crystal water); CuO 6.1 wt. % and Al2O3, 6.1 wt. % (oxide as accelerator for the condensation reaction); Ca5(PO4)3OH 5.9 wt. % (surface tension modifier for Al-melt) and Na2(HPO4) 39.2 wt. %, a casting core was built up by spraying with water as solvent according to a conventional 3D printing process. The powder mixture had a particle diameter of approximately 300-400 μm. The thickness of the individual print layers was approximately 125 μm.
  • The casting core had a green stability of approximately 3 MPa. It was heated for approximately two hours at 400° C. and exhibited thereafter a brown stability of 2.5 MPa. This suffices for employment as casting core. The finishing effort was minimal. A simple blowing off of the loose particle material with a compressed air strain was sufficient.
  • The test of the casting mold tempered to room temperature, casting with the aluminum alloy A266 at a casting temperature of 710° C., provided a good cast result with a good surface. The mold itself was easily removable by dissolving in water for a short period of time.
  • The inventive process and the therewith produced casting mold demonstrated themselves in the illustrative embodiments of the above-described examples as particularly suited for metal casting, in particular for aluminum precision casting, in the automobile industry.
  • In particular, substantial advantages can be achieved with regard to the quality of the internal surfaces.
  • The invention is not limited to only the above-described illustrative embodiments, but rather can be broadly applied.
  • Thus, the surface quality could be further improved by the addition of supplemental surface modifiers.

Claims (7)

1-6. (canceled)
7. A process for producing a three dimensional object comprising the following steps:
a. applying a layer of particles comprised of at least a mono- or polyvalent water and/or alcohol soluble metal salt upon a target surface,
b. spraying a select part of the layer, corresponding to a cross section of the object, with a liquid stream containing water and/or alcohol, so that the particles are joined in the selected part,
c. repeating steps a and b so that the joined parts of the adjacent layers combine to form the object.
8. A process according to claim 7, wherein at least one metal salt having crystal water and/or at least one metal salt having condensable anions is employed in step a.
9. A three dimensional object produced by a process comprising the following steps:
a. applying a layer of particles comprised of at least a mono- or polyvalent water and/or alcohol soluble metal salt upon a target surface,
b. spraying a select part of the layer, corresponding to a cross section of the object, with a liquid stream containing water and/or alcohol, so that the particles are joined in the selected part,
c. repeating steps a and b so that the joined parts of the adjacent layers combine to form the object.
10. The three dimensional object according to claim 9, wherein the object is a casting mold or casting core.
11. The three dimensional object according to claim 9, wherein the object is a tool or an insert for a plastic or ceramic mold.
12. A process for casting metal, comprising
a. forming a casting mold by a process comprising (i) applying a layer of particles comprised of at least a mono- or polyvalent water and/or alcohol soluble metal salt upon a target surface, (ii) spraying a select part of the layer, corresponding to a cross section of the object, with a liquid stream containing water and/or alcohol, so that the particles are joined in the selected part, and (iii) repeating steps a and b so that the joined parts of the adjacent layers combine to form a green casting mold,
b. heating the casting mold to form a brown casting mold, and
c. casting a molten metal into said casting mold.
US11/414,573 2005-04-28 2006-04-28 Process for producing a three dimensional object from particles, as well as product produced thereby Abandoned US20070057398A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102005019699.3-24 2005-04-28
DE102005019699A DE102005019699B3 (en) 2005-04-28 2005-04-28 Production of 3-dimensional objects such as casting moulds, involves coating a surface with separate layers of water- and-or alcohol-soluble metal salt and binding particles and layers together by spraying with water or alcohol

Publications (1)

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US20070057398A1 true US20070057398A1 (en) 2007-03-15

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DE (1) DE102005019699B3 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3024610B1 (en) 2013-07-24 2018-11-21 Emil Müller GmbH Salt core and additive manufacturing method for producing salt cores

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013003303A1 (en) 2013-02-28 2014-08-28 FluidSolids AG Process for producing a molded part with a water-soluble casting mold and material system for its production
DE102014214527A1 (en) * 2013-07-24 2015-01-29 Emil Müller GmbH Salt cores and generative manufacturing processes for the production of salt cores
EP3024609B1 (en) * 2013-07-24 2019-07-24 Emil Müller GmbH Salt cores and additive manufacturing method for producing salt cores
DE112018000221B4 (en) 2017-01-25 2023-02-16 Technische Universität Bergakademie Freiberg Process for the manufacture of high-temperature resistant products with improved thermomechanical properties and high-temperature resistant product
AT522989B1 (en) 2019-10-03 2021-12-15 Fill Gmbh surface treatment process

Citations (4)

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Publication number Priority date Publication date Assignee Title
US5147587A (en) * 1986-10-17 1992-09-15 Board Of Regents, The University Of Texas System Method of producing parts and molds using composite ceramic powders
US5204055A (en) * 1989-12-08 1993-04-20 Massachusetts Institute Of Technology Three-dimensional printing techniques
US5787965A (en) * 1995-09-08 1998-08-04 Aeroquip Corporation Apparatus for creating a free-form metal three-dimensional article using a layer-by-layer deposition of a molten metal in an evacuation chamber with inert environment
US6742456B1 (en) * 2002-11-14 2004-06-01 Hewlett-Packard Development Company, L.P. Rapid prototyping material systems

Family Cites Families (1)

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Publication number Priority date Publication date Assignee Title
DE10327272A1 (en) * 2003-06-17 2005-03-03 Generis Gmbh Method for the layered construction of models

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5147587A (en) * 1986-10-17 1992-09-15 Board Of Regents, The University Of Texas System Method of producing parts and molds using composite ceramic powders
US5204055A (en) * 1989-12-08 1993-04-20 Massachusetts Institute Of Technology Three-dimensional printing techniques
US5787965A (en) * 1995-09-08 1998-08-04 Aeroquip Corporation Apparatus for creating a free-form metal three-dimensional article using a layer-by-layer deposition of a molten metal in an evacuation chamber with inert environment
US6742456B1 (en) * 2002-11-14 2004-06-01 Hewlett-Packard Development Company, L.P. Rapid prototyping material systems

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3024610B1 (en) 2013-07-24 2018-11-21 Emil Müller GmbH Salt core and additive manufacturing method for producing salt cores

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