WO2003008172A1 - Procede de moulage par injection de pieces plastiques - Google Patents

Procede de moulage par injection de pieces plastiques Download PDF

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Publication number
WO2003008172A1
WO2003008172A1 PCT/DE2002/002451 DE0202451W WO03008172A1 WO 2003008172 A1 WO2003008172 A1 WO 2003008172A1 DE 0202451 W DE0202451 W DE 0202451W WO 03008172 A1 WO03008172 A1 WO 03008172A1
Authority
WO
WIPO (PCT)
Prior art keywords
plastic
injection
mold
workpieces
workpiece
Prior art date
Application number
PCT/DE2002/002451
Other languages
German (de)
English (en)
Inventor
Jürgen KÖBELIN
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2003008172A1 publication Critical patent/WO2003008172A1/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
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
    • B29C44/12—Incorporating or moulding on preformed parts, e.g. inserts or reinforcements
    • 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
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/34—Auxiliary operations
    • B29C44/3469—Cell or pore nucleation
    • B29C44/348—Cell or pore nucleation by regulating the temperature and/or the pressure, e.g. suppression of foaming until the pressure is rapidly decreased
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/34—Electrical apparatus, e.g. sparking plugs or parts thereof
    • B29L2031/3431—Telephones, Earphones
    • B29L2031/3437—Cellular phones

Definitions

  • the invention relates to a method for injection molding plastic workpieces - in particular upper, lower or interchangeable shells for mobile phones - with simultaneous application of a surface decor to the plastic workpieces according to the in-mold decoration process or the in-mold foiling process according to the Preamble of claim 1.
  • Plastic workpieces are often given an imprint. This can take place, for example, after the plastic workpiece has been produced, that is to say after injection molding in a device, by means of one or more pressure stamps. Overprints are also created using screen printing technology.
  • the imprint is first applied to a film that is inserted between the halves of an injection mold.
  • the imprint is on the side of the film that faces the future surface of the finished plastic workpiece.
  • the unprinted side of the film faces the injection mold surface that embodies the outer surface of the workpiece.
  • the imprint on the film is therefore applied in mirror image.
  • the foil will lay against the surface of the injection mold that will later be the printed surface of the workpiece.
  • the injection point for the plastic must be selected so that the plastic that shoots into the injection mold hits the printed side of the film. If it were different, the plastic could see the slide and later slide surface of the finished workpiece.
  • the foil print is detached from the foil and stored on the surface of the workpiece.
  • the imprint is now correctly aligned on the surface of the workpiece.
  • the film itself is generally not absorbed by the workpiece.
  • insert technology or in-mold foiling.
  • the film remaining on the workpiece becomes part of the wall thickness. According to the prior art, such PC films are between 0.3-0.5 mm thick.
  • the tool opens, the workpiece is ejected, the old film is removed, the new film is inserted in the plane of the mold-separating edge of the tool and the injection mold can move together again to spray the next workpiece.
  • the foils can consist of long webs with a large number of imprints, which are then fed to the injection mold synchronously with the spray cycle, likewise in cycles.
  • a wall thickness significantly smaller than 2 to 2.5 millimeters is acceptable for reasons of strength and dimensional stability.
  • Wall thicknesses of 0.6 to 1.0 millimeters are desired.
  • the tipping with conventional injection molding of these parts in connection with the IMD process or IMF process cannot be combined with one another in an acceptable quality, since the residual wall thickness when using foils, combined with low housing wall thicknesses, can no longer be filled .
  • sink marks and visible weld lines are created due to pressure drop in the tool. This also applies to housing shells and decorative interchangeable shells for mobile phones.
  • the inventor proposes to significantly reduce the shear forces of the plastic injecting into the injection mold. This reduction takes place by means of a physical blowing agent in the plastic to be processed. Such a plastic is then also referred to as structural foam.
  • a physical blowing agent in the plastic to be processed.
  • Such a plastic is then also referred to as structural foam.
  • the injection pressures of are also reduced currently 1200 to 1500 bar by more than 50 percent.
  • Surface tensions on the plastic part, which result from high shear forces during injection, can be identified with the aid of a polarizing film and can only be detected weakly around the injection point in such parts.
  • sink marks and visible weld lines are reduced because the plastic melt expands further after injection into the cavity and fills corners and unfavorable wall thickness ratios independently without emphasis.
  • Nitrogen for example, can be used as the physical blowing agent.
  • One of the advantages of this blowing agent is that it is available at low cost.
  • C02 is also a common blowing agent.
  • the gas In the case of a physical blowing agent, the gas is in dissolved form (super-critical state) during the addition to the plastic melt. When spraying, the gas is released again, at least in part. This also significantly reduces the density of the plastic material. Since the density is lower, the shear forces cannot be as great as with a plastic that contains no physical blowing agent (in contrast to physical blowing agents, chemical blowing agents work through a chemical reaction).
  • wall thickness that is significantly less than 2 millimeters.
  • wall thicknesses of 1.5 to 0.6 millimeters can now be sprayed without blurring an imprint using the IMD process or the IMF process.
  • the wall thickness is preferably between 1.2 and 2.0 millimeters.
  • the method according to the invention also significantly reduces the specific injection pressure (by 30-50%). He is carries according to the invention only between 300 and 1000 bar.
  • the injection pressure is preferably 500 to 800 bar or 600 to 750 bar.
  • FIG. 1 shows a schematic cross section through an injection mold.
  • FIG. 1 A cross section through a closed injection mold 1 can be seen in FIG.
  • the injection mold 1 consists of a first mold half 5 and a second mold half 6. Further components of an injection molding machine have been omitted here for reasons of clarity.
  • a film 3 with an imprint lies in the plane of the mold-separating edge 2 of the injection mold 1 and on the inner contour of the first mold half 5.
  • the surface with the imprint 8 of the film 3 faces the upper surface of the plastic workpiece 4.
  • a sprue 7 serves to fill the injection molding tool 1. These sprue 7 are provided with a nozzle-like constriction at their end facing the plastic workpiece 4.
  • a needle valve 9 doses the amount of plastic melt. Without this, the plastic would expand into the cavity in an uncontrolled manner. As a result of this narrowing, the plastic undergoes a corresponding heating when it is injected and, as a result, additional liquefaction.
  • the narrowing also makes it easier to separate the plastic workpiece 4 from the sprue 7 because of the small cross section and the associated minimal holding forces between the finished plastic workpiece 4 and the sprue when the finished workpiece is ejected.
  • the invention thus proposes a method for injection molding plastic workpieces - in particular upper, lower or interchangeable shells for mobile telephones - with simultaneous application of a surface decor to the plastic workpieces using the in-mold decoration method or in-r ⁇ ould foiling -Procedure, wherein a physical blowing agent is added to the plastic to reduce the injection pressure.

Landscapes

  • Injection Moulding Of Plastics Or The Like (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

L'invention concerne un procédé de moulage par injection de pièces plastiques, en particulier de boîtiers supérieurs, inférieurs ou de boîtiers de rechange de téléphones portables. Le procédé selon l'invention permet par ailleurs d'appliquer un décor de surface sur les pièces plastiques selon le procédé de décoration dans le moule ou de pelliculage dans le moule, un agent propulseur physique étant additionné au plastique afin d'abaisser la pression d'injection.
PCT/DE2002/002451 2001-07-16 2002-07-04 Procede de moulage par injection de pieces plastiques WO2003008172A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10134536 2001-07-16
DE10134536.4 2001-07-16

Publications (1)

Publication Number Publication Date
WO2003008172A1 true WO2003008172A1 (fr) 2003-01-30

Family

ID=7691958

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE2002/002451 WO2003008172A1 (fr) 2001-07-16 2002-07-04 Procede de moulage par injection de pieces plastiques

Country Status (1)

Country Link
WO (1) WO2003008172A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005006074A1 (de) * 2005-02-10 2006-08-17 Leonhard Kurz Gmbh & Co. Kg Mehrschichtfolie, damit dekorierter Spritzgussartikel und Verfahren zur Herstellung des dekorierten Spritzgussartikels
WO2008107329A2 (fr) 2007-03-07 2008-09-12 BSH Bosch und Siemens Hausgeräte GmbH Appareil frigorifique
DE102004004237C5 (de) * 2004-01-27 2009-11-12 Woco Industrietechnik Gmbh Verfahren zur Herstellung von mikroporösen Kunststoffprodukten und die nach diesem Verfahren erhältlichen Formteile, Profile und Granulate
CN107414413A (zh) * 2016-05-24 2017-12-01 东莞市真品五金散热科技有限公司 一种手机外壳加工方法、手机外壳及手机

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0391854A1 (fr) * 1989-04-03 1990-10-10 Vanotti, Gérard Procédé de fabrication de pièces en matière thermoplastique à paroi mince et installation pour la mise en oeuvre du procédé
EP0799853A1 (fr) * 1996-04-04 1997-10-08 MITSUI TOATSU CHEMICALS, Inc. Produit thermoplastique de résine et sa production
JP2001150512A (ja) * 1999-11-29 2001-06-05 Japan Steel Works Ltd:The 発泡成形方法及び装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0391854A1 (fr) * 1989-04-03 1990-10-10 Vanotti, Gérard Procédé de fabrication de pièces en matière thermoplastique à paroi mince et installation pour la mise en oeuvre du procédé
EP0799853A1 (fr) * 1996-04-04 1997-10-08 MITSUI TOATSU CHEMICALS, Inc. Produit thermoplastique de résine et sa production
JP2001150512A (ja) * 1999-11-29 2001-06-05 Japan Steel Works Ltd:The 発泡成形方法及び装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 200153, Derwent World Patents Index; Class A32, AN 2001-485004, XP002217330 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102004004237C5 (de) * 2004-01-27 2009-11-12 Woco Industrietechnik Gmbh Verfahren zur Herstellung von mikroporösen Kunststoffprodukten und die nach diesem Verfahren erhältlichen Formteile, Profile und Granulate
DE102005006074A1 (de) * 2005-02-10 2006-08-17 Leonhard Kurz Gmbh & Co. Kg Mehrschichtfolie, damit dekorierter Spritzgussartikel und Verfahren zur Herstellung des dekorierten Spritzgussartikels
DE102005006074B4 (de) * 2005-02-10 2009-12-10 Leonhard Kurz Gmbh & Co. Kg Dekorierter Spritzgussartikel und Verfahren zur Herstellung des dekorierten Spritzgussartikels
US7976931B2 (en) 2005-02-10 2011-07-12 Leonhard Kurz Stiftung & Co. Kg Multi-layer film, injection molded article decorated therewith and process for the production of the decorated injection molded article
WO2008107329A2 (fr) 2007-03-07 2008-09-12 BSH Bosch und Siemens Hausgeräte GmbH Appareil frigorifique
WO2008107329A3 (fr) * 2007-03-07 2009-05-22 Bsh Bosch Siemens Hausgeraete Appareil frigorifique
CN107414413A (zh) * 2016-05-24 2017-12-01 东莞市真品五金散热科技有限公司 一种手机外壳加工方法、手机外壳及手机

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