WO1993025365A1 - Procede utilise en association avec la production de pieces en plastique - Google Patents

Procede utilise en association avec la production de pieces en plastique Download PDF

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Publication number
WO1993025365A1
WO1993025365A1 PCT/FI1993/000244 FI9300244W WO9325365A1 WO 1993025365 A1 WO1993025365 A1 WO 1993025365A1 FI 9300244 W FI9300244 W FI 9300244W WO 9325365 A1 WO9325365 A1 WO 9325365A1
Authority
WO
WIPO (PCT)
Prior art keywords
binding agent
core
plastic
forming
forming material
Prior art date
Application number
PCT/FI1993/000244
Other languages
English (en)
Inventor
Harri Sahari
Eerik TÖRMÄ
Hannu JYLHÄ
Original Assignee
Harri Sahari
Toermae Eerik
Jylhae Hannu
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
Application filed by Harri Sahari, Toermae Eerik, Jylhae Hannu filed Critical Harri Sahari
Priority to AU40734/93A priority Critical patent/AU4073493A/en
Publication of WO1993025365A1 publication Critical patent/WO1993025365A1/fr

Links

Classifications

    • 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
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
    • B29C33/52—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles soluble or fusible
    • 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
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
    • B29C33/58—Applying the releasing agents
    • 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
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor

Definitions

  • the present invention relates to a procedure in association with production of plastic pieces, particularly plastic pieces containing interior shapes, such as cavity spaces, counterdrafts and equivalent, essentially without any connecting joints, in which method the pieces made of plastic material are produced upon a core, by making the core from a granular forming material and from a binding agent binding the forming grains together, said core being removed after completing the piece.
  • the pressures in processing plastics are 600 to 800 bar at greatest, so that the conditions compared with metal processing are completely different. Also removing cores from plastic casts are con ⁇ siderably more problematic than in metal casts because such core removal techniques cannot be used with plastics which are generally known and used in casting technology. Core removal techniques like these are for instance clattering, vibration, slinger blowing, thermal treatments, etc. A problem related to using cores in pro- ducing plastics is also that the plastics in molten state tend to penetrate into the core material.
  • molten core technique in which for the core material a metal alloy with a low melting point is used.
  • An essential drawback of the method is, however, that the core material used is extremely expensive so that the method can be used only in producing expensive special items.
  • the core material also sets certain prerequisites for the production line, thus raising even more the manufacturing costs.
  • dissoluble plastic core is used. In that method, mineral-reinforced mixed polymer of acrylic acid and acrylic ester is used for the core material.
  • One of the problems of the method lies in the production of the core. Also this method is quite costs- involving.
  • the core is produced from a plastic dissoluble in an alkaline solution, on top of which plastic is then cast.
  • the production conditions are special in character, because the production requires continuous maintenance of the vacuum.
  • the materials are different from those used in the present invention.
  • the object of the present invention is to utilize the prior art method known in the FI patent No. 78,247 (US. patent No. 5,158,130), intended for casting metals in manu ⁇ facturing plastic pieces and to develop a method which is, in comparison with the methods used in producing various plastic pieces, substantially simpler and more economic.
  • the aim of the invention is furthermore to provide a method which is appropriate for use in producing various products, such as injection moulding of thermoplastics and thermosetting plastics, rolling and lamination of thermosetting plastics, and other equivalent production methods.
  • the invention is mainly characterized in that for the binding agent water- soluble inorganic salt is used which as a binding agent solution dissolved in water is mixed in a granular forming material and the chemical properties whereof being unchanged in the forming incident and during the production process of the plastic piece, and that the combination of the binding agent and the forming material is so selected that the main minerals of the binding agent and the forming material are chemically non-reacting with each other at the forming temperature and in the course of the production process of the plastic pieces, so that the binding agent in the for ⁇ ming incident is crystallized by heating the core produced from the aqueous solution thereof for producing from the binding agent a fixed bridge binding the forming mat ⁇ erial grains with each other between the forming material grains, and prior to producing the plastic piece, the core is coated with a coating agent non-adhering to the plastic material, whereby the binding agent and coating agent can after the production process of the plastic pieces be dissolved in water or in non-saturated aqueous
  • the moulds and cores are produced by binding the forming material grains together with an inorganic water-soluble salt, the melting point thereof being above the temperatures used in the production process of the plastic piece.
  • an inorganic compound with a high melting point is used, particularly an inorganic water-soluble salt.
  • An essential feature of the binding agent is that the melting point thereof is so high that it will not in general melt even at casting temperatures.
  • binding agent As regards the properties of the binding agent, they are such that the agent will not react chemically at temperatures implemented in forming and the cast with the main minerals of the forming material grains, and thus, it will not form non-water- soluble compounds.
  • the binding agent solution forms a liquid bridge produced by liquid gathering in the contact points of the forming material grains.
  • the binding agent solution has a high viscosity and it is provided with a great adhesion ability with the main mineral of the forming material grains, resulting in that the forming material grains are "glued" to each other and hold the forming mass in one piece and formable, although the binding agent in itself is still in solution form.
  • Breaking up the casting is carried out by dissolving the water-soluble binding agent off with water from the joints of the forming material grains and from the sur ⁇ faces of the grains.
  • the forming material grains can be used again right after being washed and dried.
  • the drying can be carried out e.g. by means of centrifugation.
  • the amount of the binding agent of the dissolved agent used in the method is about 0.5 to 20 per cent by weight of the total amount of the forming material.
  • the amount of the dissolved binding agent is preferably 1 to 5 per cent by weight of the forming material.
  • binding agent sodium aluminate NaAlO 2 or sodium metasilicate Na 2 SiO 3 , the molar ratio of each one being preferably 1: 1.
  • quartz (SiO 2 ), corundum (Al 2 O 3 ) or other mineral grain not reacting in process temperatures with the binding agents mentioned at (1).
  • binding agent and forming grain material any suitable combination can be used, in which the binding agent and the forming grain material comply to the principles presented above in (a), (b) and (k).
  • the binding agent / forming grain material com ⁇ binations presented in (1) and (2) are merely preferred examples of potential alternatives.
  • FIG. 1 An example is presented below of how a cast mould or a core is made utilizing the method of the present invention.
  • the example is demonstrated by Figs 1 to 8 of the accompanying drawing, showing as a picture series the different phases of core production and use of the core in making a plastic piece.
  • a requisite forming mass is produced first by mixing forming material grains and a binding agent solution at 20 to 120°C so that the binding agent solution soils all over the surfaces of the forming material grains. After mixing the forming mass, the forming of the mould and preparation of the core are carried out, still at 20 to 120°C. If proceeding in usual manner, the forming could be accomplished as fol ⁇ lows:
  • a loosely coherent mould or core could be produced.
  • the surface of the core should, as described above, be made as hard and even as possible, in order to be non-penetratable by the plastic. Therefore, e.g. the following procedure presented in Figs. 1 to 3 is adopted in the invention.
  • a hollow core support 3 is placed in a lower mould 2, an upper mould 1 being fitted on top of the lower mould 2, and requisite amount of core mass A is carried into the mould cavity 4.
  • a press 5 is disposed into the mould cavity 4 upon the core mass A. With the aid of said press 5 the core mass A is pressed, or packed into mould 1,2. The press 5 has been compressed into the mould cavity 4 with a very great force so that the pressure influencing the core mass A is considerable in the packing phase.
  • the "fresh" mould or core produced in the above-described manner is brought into a desired processing strength by drying it partly or completely.
  • the drying can be carried out e.g. using the following alternative procedures.
  • the drying of the mould and core can be carried out at conventional temperature e.g. from 130 to 200°C.
  • Crystallizing the binding agent from the water solution thereof can be carried out so that the mould and/or core are/is brought into an electrical and/or magnetic field varying in direction, whereby the heating of the forming mass is carried out by means of the increasing kinetic energy of the electrically or magnetically polarized molecules or atom groupings.
  • This can be implemented e.g. by heating the mould or core being produced in a microwave oven, that is, in high-frequency oven, so that because of the motion of the water dipoles contained in the forming mass, the forming mass becomes internally heated and in all parts simultaneously hardened.
  • the mould or the core can also be dried in a heating apparatus, in which it is subjected to variations of direction of an inductive or capa- citative field. Also in an apparatus like this the water dipoles in the forming mass are set in motion, because of which the forming mass heats internally and is in all parts hardened simultaneously, as in the microwave oven.
  • a mould or a core heated according to any of the methods presented above in (1) or (2) can be set, in order to remove the dissolvent of the binding agent, like water, at a desired temperature, e.g. from 50 to 150°C, into partial vacuum, whereby by making use of the thermal energy of the binding agent and the forming material the dissolvent of the binding agent, like water, is evaporated or boiled off from the mould or the core, whereby the binding agent turns into crystalline and/or amorphous state owing to the physical phenomenon, but maintaining its chemical composition as it was.
  • a desired temperature e.g. from 50 to 150°C
  • the drying of the mould or the core may also be accomplished using heating of the mould or core according to either (1) or (2), and the partial vacuum according to (3) simultaneously, whereby the forming mass need not be preheated.
  • a fixed mould or core produced as described above must in general be coated with different coating materials, depending on the plastic material.
  • the coating is accomplished for the reason that no plastic should enter the plastic or core material.
  • coating is used for preventing the erosion caused by the running of the plastics in the core and in the mould. Furthermore, with a coating the catching of the plastic onto the mould or the core is prevented.
  • the coating material must be such which will not dissolve the binding agent of the forming mass.
  • the coating should be made of a material which does not catch the plastic material itself.
  • a coating is applied on the surface of a core or a mould e.g. by dipping, spraying, brushing, or electrostatically as a powder.
  • Fig. 5 demonstrates the coating of the core B, carried out for reinforcing and sealing the core B.
  • Fig. 5 illustrates coating by spraying with a spray means 7. Most preferably a binding agent containing coating solution is used for the coating.
  • the core B is then dried.
  • the purpose of the coating is to provide the core B with a smooth, sealed and very hard surface a, which is non-penetratable by plastic.
  • Other differences to moulds and cores used in casting metals in the method according to the invention lie therein that producing plastics requires that a core, respectively a mould, possesses a considerably greater strength, which can be provided using greater quantities of the binding agent.
  • the grain size of the forming mass must also in general be selected to be finer than in metal castings.
  • FIG. 6 is presented a situation in which a coated and dried core B has been inserted in an die-casting mould consisting of two mould halves 11,12 and plastic p has been sprayed into the cavity of mould 11,12.
  • the hollow chaplet 3 is still in place.
  • the plastic piece 10 and the core B, together with the chaplet 3 are removed from the die-casting mould 11,12, as shown in Fig. 7.
  • the breaking up of the moulds and cores can be carried out simply by dissolving the binding agent of the forming material off with water because the binding agent used therein is water-soluble. Dissolving the binding agent can be carried out with e.g. water spray, steam spray, or by immersing the piece into water.
  • the forming material grains are separated from the water solution mixture after the wash and drying treatment for reuse.
  • the water / binding agent solution is appropriate for the breaking up until the binding agent content of the sol ⁇ ution has grown into 30 to 50 per cent by weight.
  • the sludge produced from the coating material can be removed by filtering from the breaking up solution.
  • the binding agent can be separated from the breaking up solution in cold state by crystal ⁇ lizing or evaporating the solution until dry.
  • the binding agent solution is highly alkaline, but, however, not making the waterways euthropic, whereby it will not cause environmental detriments.
  • Fig. 8 demonstrates the breaking up of the core and the further processing of the core mass.
  • binding agent solution or water has been supplied through the hollow chaplet 3 for dissolving the core away from inside the plastic piece 10.
  • the plastic piece 10 is ready. From the core mass A obtained from inside the plastic piece 10 the extra binding agent and/or water is removed e.g. as shown in Fig. 8, by draining it through a net 14, a filter or equivalent into a draining vessel 13, so that moist mass A is obtained, from which a new core can be made. From the situation presented in Fig. 8 the core mass is returned to the phase shown in Fig. 1.

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

Abstract

L'invention concerne un procédé utilisé en association avec la production de pièces en plastique, et plus particulièrement des pièces contenant des espaces intérieurs tels que des cavités, des contre-dépouilles et autres logements équivalents, essentiellement sans raccords. Le procédé selon l'invention consiste à produire les pièces à former à partir d'une matière plastique sur un noyau se composant d'une matière de formage granuleuse et d'un liant qui lie les grains entre eux, ledit noyau étant enlevé une fois la pièce terminée. Pour ce qui concerne le liant, on utilise un sel inorganique soluble dans l'eau, ledit sel se présentant sous la forme d'une solution liante dissoute dans l'eau, que l'on mélange à une matière de formage granuleuse, les propriétés chimiques dudit liant restant inchangées pendant la phase de formage et le processus de production de la pièce en plastique. La combinaison du liant et de l'agent de formage est sélectionnée de façon que les principaux minéraux du liant et de la matière de formage ne réagissent pas au contact les uns des autres à la température de formage, et pendant le processus de formage de la pièce en plastique. Au cours de la phase de formage, le liant est cristallisé par chauffage du noyau obtenu à partir de la solution liante aqueuse, afin de produire un point fixe liant les grains de matière de formage. Une fois le processus de production des pièces en plastique achevé, le liant peut être dissous dans l'eau ou dans une solution aqueuse insaturée de liant afin de casser le noyau et le sortir de la pièce finie.
PCT/FI1993/000244 1992-06-11 1993-06-07 Procede utilise en association avec la production de pieces en plastique WO1993025365A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU40734/93A AU4073493A (en) 1992-06-11 1993-06-07 Procedure in association with production of plastic pieces

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI922716 1992-06-11
FI922716A FI922716A (fi) 1992-06-11 1992-06-11 Foerfarande i samband med framstaellning av plaststycken

Publications (1)

Publication Number Publication Date
WO1993025365A1 true WO1993025365A1 (fr) 1993-12-23

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ID=8535468

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1993/000244 WO1993025365A1 (fr) 1992-06-11 1993-06-07 Procede utilise en association avec la production de pieces en plastique

Country Status (3)

Country Link
AU (1) AU4073493A (fr)
FI (1) FI922716A (fr)
WO (1) WO1993025365A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0909623A1 (fr) * 1997-10-14 1999-04-21 MAGNETI MARELLI S.p.A. Installation pour enlever des noyaux de sel d'objets moulés par coulée sous pression ou par injection
JP2004520972A (ja) * 2001-02-23 2004-07-15 バンティコ ゲーエムベーハー モデルを製造する方法
WO2004071738A1 (fr) * 2003-02-11 2004-08-26 Ashland-Südchemie- Kernfest Gmbh Substances de revetement pour noyaux de coulee
WO2013108106A3 (fr) * 2012-01-16 2013-10-31 Toyota Jidosha Kabushiki Kaisha Procédé de fabrication de corps de sac
EP3984715A1 (fr) * 2020-10-13 2022-04-20 Technische Universität München Noyau soluble renforcé en fibre

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59136214A (ja) * 1983-01-26 1984-08-04 Niigata Eng Co Ltd 水溶性中子を用いたプラスチツク鋳造方法
WO1984003857A1 (fr) * 1983-03-28 1984-10-11 Park Chem Co Procede de moulage par pression utilisant des noyaux de sel et composition pour fabriquer des noyaux
US4590026A (en) * 1983-06-20 1986-05-20 Namba Press Works Co. Ltd. Process for making reinforcing layers on inner surfaces of complicated cavities
EP0313923A2 (fr) * 1987-10-28 1989-05-03 Bayerische Motoren Werke Aktiengesellschaft, Patentabteilung AJ-3 Procédé et moyen de moule pour la fabrication d'objets à contre-dépouille en matière plastique
WO1989005204A1 (fr) * 1987-12-08 1989-06-15 Harri Sahari Procede de preparation de moules et de noyaux utilises dans le coulage des metaux
EP0471459A1 (fr) * 1990-07-28 1992-02-19 Westland Aerostructures Limited Procédé pour fabriquer des éléments perforés à partir de matériaux composites

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59136214A (ja) * 1983-01-26 1984-08-04 Niigata Eng Co Ltd 水溶性中子を用いたプラスチツク鋳造方法
WO1984003857A1 (fr) * 1983-03-28 1984-10-11 Park Chem Co Procede de moulage par pression utilisant des noyaux de sel et composition pour fabriquer des noyaux
US4590026A (en) * 1983-06-20 1986-05-20 Namba Press Works Co. Ltd. Process for making reinforcing layers on inner surfaces of complicated cavities
EP0313923A2 (fr) * 1987-10-28 1989-05-03 Bayerische Motoren Werke Aktiengesellschaft, Patentabteilung AJ-3 Procédé et moyen de moule pour la fabrication d'objets à contre-dépouille en matière plastique
WO1989005204A1 (fr) * 1987-12-08 1989-06-15 Harri Sahari Procede de preparation de moules et de noyaux utilises dans le coulage des metaux
EP0471459A1 (fr) * 1990-07-28 1992-02-19 Westland Aerostructures Limited Procédé pour fabriquer des éléments perforés à partir de matériaux composites

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN, Vol. 8, No. 263, M-342; & JP,A,59 136 214, (NIIGATA TEKKOSHO K.K.), 4 August 1984. *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0909623A1 (fr) * 1997-10-14 1999-04-21 MAGNETI MARELLI S.p.A. Installation pour enlever des noyaux de sel d'objets moulés par coulée sous pression ou par injection
US6053186A (en) * 1997-10-14 2000-04-25 MAGNETI MARELLI S.p.A. Machine for removing salt cores trapped in pressure die-cast or injection moulded articles
JP2004520972A (ja) * 2001-02-23 2004-07-15 バンティコ ゲーエムベーハー モデルを製造する方法
WO2004071738A1 (fr) * 2003-02-11 2004-08-26 Ashland-Südchemie- Kernfest Gmbh Substances de revetement pour noyaux de coulee
US7717994B2 (en) 2003-02-11 2010-05-18 Ashland-Sudchemie-Kernfest Gmbh Coating materials for cores
WO2013108106A3 (fr) * 2012-01-16 2013-10-31 Toyota Jidosha Kabushiki Kaisha Procédé de fabrication de corps de sac
US9409317B2 (en) 2012-01-16 2016-08-09 Toyota Jidosha Kabushiki Kaisha Manufacturing method of bag body
EP3984715A1 (fr) * 2020-10-13 2022-04-20 Technische Universität München Noyau soluble renforcé en fibre
US12053909B2 (en) 2020-10-13 2024-08-06 Technische Universitat Munchen Fiber-reinforced soluble core

Also Published As

Publication number Publication date
FI922716A0 (fi) 1992-06-11
FI922716A (fi) 1993-12-12
AU4073493A (en) 1994-01-04

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