EP0502568B1 - Dispositif pour porter des matéraux plastiques dans un état de viscosité réduite - Google Patents

Dispositif pour porter des matéraux plastiques dans un état de viscosité réduite Download PDF

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Publication number
EP0502568B1
EP0502568B1 EP92200523A EP92200523A EP0502568B1 EP 0502568 B1 EP0502568 B1 EP 0502568B1 EP 92200523 A EP92200523 A EP 92200523A EP 92200523 A EP92200523 A EP 92200523A EP 0502568 B1 EP0502568 B1 EP 0502568B1
Authority
EP
European Patent Office
Prior art keywords
state
die
reduced viscosity
hollow member
mass
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
EP92200523A
Other languages
German (de)
English (en)
Other versions
EP0502568A3 (en
EP0502568A2 (fr
Inventor
Peter Dr. Geittner
Hans Jürgen Dr. Lydtin
Gerd Dr. Romanowski
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.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Patentverwaltung GmbH
Koninklijke Philips Electronics NV
Philips Electronics NV
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 Philips Patentverwaltung GmbH, Koninklijke Philips Electronics NV, Philips Electronics NV filed Critical Philips Patentverwaltung GmbH
Publication of EP0502568A2 publication Critical patent/EP0502568A2/fr
Publication of EP0502568A3 publication Critical patent/EP0502568A3/de
Application granted granted Critical
Publication of EP0502568B1 publication Critical patent/EP0502568B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B17/00—Details of, or accessories for, apparatus for shaping the material; Auxiliary measures taken in connection with such shaping
    • B28B17/02—Conditioning the material prior to shaping
    • B28B17/026—Conditioning ceramic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
    • B28B3/20—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
    • B28B3/20—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded
    • B28B3/24—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded by reciprocating plunger
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
    • B30B11/02—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space
    • B30B11/022—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space whereby the material is subjected to vibrations

Definitions

  • the invention relates to a device for converting thixotropic plastic masses into a state of reduced viscosity at room temperature with a die for receiving the mass, with a press ram for advancing the mass in the direction of an outlet opening and with a sonotrode coupled to an ultrasonic transducer with essentially flat face.
  • a device of this type is known for example from DE-A-3 511 452.
  • Ceramic bodies recently also increasingly molded parts from other materials, such as Quartz glass are produced from powdery starting materials by first compressing them to a porous shaped body using suitable processes and then or simultaneously sintering them into dense bodies at higher temperatures, but below the melting temperature.
  • An advantage of this procedure is that the shaping can take place at room temperature. In this way, for example, decomposition processes or changes in stoichiometry are avoided in the case of masses of complex chemical structure.
  • the powdered starting materials are processed into highly filled suspensions and mixed with suitable additives such as organic binders, lubricants, emulsifiers, stabilizers etc.
  • suitable additives such as organic binders, lubricants, emulsifiers, stabilizers etc.
  • the suspensions are homogenized by intensive mixing and shearing, for example by stirring or kneading, the aim being at the same time to destroy particle agglomerates.
  • Ceramic masses obtained in this way are then brought into the desired shape by suitable processes, such as casting, pressing, rolling, extruding.
  • suitable processes such as casting, pressing, rolling, extruding.
  • the mass must still be flowable so that it can be deformed when subjected to forces, on the other hand, however, the rheological yield point must be large enough to avoid undesired deformation of the body after the actual shaping.
  • the solids content of the mixtures has an upper limit. This upper limit depends on the particle sizes and the surface chemistry of the ceramic starting material used as well as additives (e.g. binders) and the dispersant used.
  • the highest possible solids content in the porous green body is desirable. This considerably reduces the risk of deformation or even cracking during sintering.
  • the size of the furnace used for sintering can be reduced. This is particularly important for large workpieces and high sintering temperatures, such as in the production of quartz glass bodies from suspensions containing submicroscopic SiO2 particles.
  • a high solids content leads to greater mechanical strength of the green body and to a lower dry shrinkage, which likewise reduces the risk of cracking and deformation.
  • Highly filled, very homogeneous masses can be produced, for example, by a centrifugal separation process as described in DE-A-37 02 025. With the help of the centrifugal force, successively thin layers of solid particles are separated from thin, low-concentration suspensions. Solid, compact, porous bodies obtained in this way can then be converted and deformed into a state of reduced viscosity using a method known from DE-A-35 11 452 and a device known from this prior publication. In this known method, an ultrasonic field is coupled into the ceramic mass using the known device. The shear forces exerted on the solid particles disrupt the attractive forces acting between the particles. This (thixotropy effect) reduces the viscosity of the mass, so that it becomes fluid. In this state, the material can be shaped into tubular or rod-shaped bodies, for example by extrusion.
  • this method can be used to convert solid, highly filled masses into a softened, deformable or even into a fluid, fluid state.
  • the mass to be deformed is located in a die provided with an outlet opening.
  • a press ram designed as an ultrasonic sonotrode is inserted into the die.
  • the ceramic mass converted into a state of reduced viscosity by the action of ultrasound is then pressed out through the outlet opening when the ultrasound sonotrode serving as a press ram is advanced.
  • the remaining material in the recipient is less and less influenced by the injected ultrasound energy as the distance from the sonotrode stamp increases.
  • the invention has for its object to improve the device described above so that a highly filled, fine powder particles plastic, ceramic mass is converted into a state of reduced viscosity by coupling an ultrasonic field evenly.
  • An advantageous development of the device according to the invention is characterized by a press ram designed as a screw conveyor.
  • a thixotropic mass to be converted into a state of reduced viscosity is liquefied uniformly under constant pressure and preferably continuously in e.g. a mold can be pressed out of the device. Continuous process control is particularly advantageous with regard to large series production.
  • the advantage of the device according to the invention compared to the device known from DE-A-35 11 452 is that the entire mass to be liquefied reaches the effective area of the sonotrode.
  • the entire mass filled in the recipient is subjected to the same treatment, since the residence time of the material penetrated in the effective area of the sonotrode is almost independent of the initial position of the material in the recipient.
  • outlet opening for the liquefied mass can have any shape, since it is independent of the shape of the sonotrode. Depending on the type of subsequent shaping, slit or circular openings with different dimensions are possible.
  • thermoplastic compositions From US-A-3,523,147 a method and an apparatus for the hot extrusion of thermoplastic compositions is already known, wherein a static pressure is applied to granular, solid thermoplastic material in order to compress the material and at the same time a fluctuating compression pressure with a frequency which is at least is in the sound range, which is a reversible elastic deformation of the thermoplastic Material causes, whereby the thermoplastic material is heated and melted.
  • the frequency is selected so that the heating of the material is optimal.
  • the vibrating press ram has a conical end face that allows maximum pressure to be exerted on a punctiform area. This device is not suitable for generating a uniform mechanical shaking movement, as is required for the liquefaction of thixotropic masses at room temperature.
  • the masses to be processed contain organic constituents, such as, for example, organic, polymeric binders, it is advantageous to use the material located in front of the sonotrode via the flange connecting the two hollow bodies and / or to cool via the ram in order to prevent decomposition of the organic compounds by the heating of the material which occurs during the ultrasound treatment.
  • organic constituents such as, for example, organic, polymeric binders
  • the flange or the press ram must then contain lines for a cooling medium.
  • the figure shows schematically an embodiment of the device according to the invention with a press ram in section.
  • the plastic, ceramic mass 8 to be processed which consists of fine powder particles and liquid binders, is located in the second hollow body 5 in front of the sonotrode 2.
  • the plastic mass 8 is pressed against the surface of the sonotrode 2 by a press ram 1 under a pressure p.
  • a region of reduced viscosity 9 is formed there due to the shear forces acting on the particles due to the ultrasound field.
  • the flowable material 9 emerges from the second hollow body 5 through an outlet opening 7 and can be further shaped before the re-consolidation.
  • 300 g of this not yet dried material are filled into the device according to FIG. 1.
  • the material located here is liquefied by the shear forces acting on the particles and emerges from the outlet opening 7, which in this example has a gap width of 0.5 mm.
  • the pressure p remains constant at 2.5 bar during the entire test period.
  • the viscosity of the escaping liquefied mass 9 is approximately 65 mPas and is constant during the test period.
  • a porous SiO2 mass produced as in the first exemplary embodiment, but which in addition to H2O still contains 7% by weight of polyvinyl alcohol as a binder and 3.0% by weight of triethylene glycol as a plasticizer, is converted into a state of reduced viscosity as described above. With this material composition, the pressure required for this is p 9 bar.
  • the escaping liquefied mass 9 is viscous and solidifies after a period of about 5 minutes.
  • the material can be drawn out with the help of a squeegee to a film with a thickness of 20 ⁇ m and a green density of 38% of the theoretical density.
  • Example 2 The procedure is as described for Example 2. However, as a ceramic solid, finely divided BaTiO3 has been used.
  • the centrifuged sediment has a solids content of 81% by weight and contains 3.1% by weight of polyvinyl alcohol and 2.5% by weight of triethylene glycol.
  • a constant pressure of p 21 bar is required for pressing.
  • the liquefied mass 9 can be rolled out to a film with a homogeneous density of 45% of the theoretical density.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Press-Shaping Or Shaping Using Conveyers (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Control Of Non-Electrical Variables (AREA)

Claims (2)

  1. Dispositif pour amener des masses plastiques thixotropes dans un état de viscosité réduite à température ambiante avec une matrice (4, 5, 6) destinée à recevoir la masse, avec un chasse-piston (1) pour l'avance de la masse dans la direction d'une ouverture de sortie (7) et avec un sonotrode (2) raccordé à un producteur d'ultrasons (3) ayant une face frontale essentiellement plane, caractérisé par
    - une matrice en deux pièces, qui se compose d'une première (4) et d'une deuxième cavité (5), les cavités étant reliées l'une (4) à l'autre (5) par affleurement par l'intermédiaire d'une bride (6) et présentant, respectivement, une ouverture sur leur face frontale;
    - un sonotrode (2), qui est ajusté à glissement dans la première cavité (4) et raccordé à un oscillateur piézo-électrique (3) disposé devant l'ouverture côté face frontale de la première cavité, (4) et
    - un chasse-piston (1), qui peut glisser dans la deuxième cavité (5) prévue pour recevoir la masse (8) à amener dans un état de viscosité réduite par l'ouverture côté face frontale de la deuxième cavité (5) dans la direction du sonotrode (2) et expulse de la deuxième cavité (5) la masse (8) à l'état de viscosité réduite (9) par l'intermédiaire d'une ouverture de sortie (7) immédiatement adjacente au sonotrode.
  2. Dispositif selon la revendication 1, caractérisé par un chasse-piston (1) conçu comme une vis sans fin.
EP92200523A 1991-03-02 1992-02-24 Dispositif pour porter des matéraux plastiques dans un état de viscosité réduite Expired - Lifetime EP0502568B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4106645A DE4106645A1 (de) 1991-03-02 1991-03-02 Vorrichtung zur ueberfuehrung von plastischen massen in einen zustand erniedrigter viskositaet
DE4106645 1991-03-02

Publications (3)

Publication Number Publication Date
EP0502568A2 EP0502568A2 (fr) 1992-09-09
EP0502568A3 EP0502568A3 (en) 1993-03-31
EP0502568B1 true EP0502568B1 (fr) 1995-11-08

Family

ID=6426297

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92200523A Expired - Lifetime EP0502568B1 (fr) 1991-03-02 1992-02-24 Dispositif pour porter des matéraux plastiques dans un état de viscosité réduite

Country Status (3)

Country Link
EP (1) EP0502568B1 (fr)
JP (1) JPH04354007A (fr)
DE (2) DE4106645A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2292105B8 (en) * 1994-08-10 1999-07-05 Kameel Diab Sawalha System for producing discrete components or articles from continuous fibre metal matrix composite
IT1299900B1 (it) * 1998-03-12 2000-04-04 Giuliano Rivi Procedimento ed apparecchio per la formatura con l'ausilio di ultrasuoni di articoli in materiale plastico.
DE10024762B4 (de) * 2000-05-19 2005-06-23 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Verfahren zur Formgebung gleitfähiger Massen durch Druckförderung und Vorrichtung zur Durchführung des Verfahrens
DE102005024171A1 (de) * 2005-03-22 2006-09-28 Grünenthal GmbH Verfahren und Vorrichtung zur Ultraschallverpressung einer Tablette oder einer multipartikulären Arzneiform

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1441796A (fr) * 1965-05-07 1966-06-10 Aeroprojects Inc Appareil d'extrusion ultrasonique
US3523147A (en) * 1967-09-28 1970-08-04 Usm Corp Plastication of thermoplastic materials
EP0045564A3 (fr) * 1980-07-29 1982-04-21 Imperial Chemical Industries Plc Extrusion
DE3511452A1 (de) * 1985-03-29 1986-10-09 Philips Patentverwaltung Gmbh, 2000 Hamburg Verfahren und vorrichtungen zur herstellung von glaskoerpern
US4793954A (en) * 1987-08-17 1988-12-27 The B. F. Goodrich Company Shear processing thermoplastics in the presence of ultrasonic vibration
JPH01218813A (ja) * 1988-02-29 1989-09-01 Komatsu Ltd プラスチックの成形方法
JPH069845B2 (ja) * 1988-11-24 1994-02-09 出光興産株式会社 押出成形方法とその装置
JPH02286312A (ja) * 1989-04-28 1990-11-26 Kawasaki Steel Corp 射出成形方法

Also Published As

Publication number Publication date
DE4106645A1 (de) 1992-09-03
EP0502568A3 (en) 1993-03-31
EP0502568A2 (fr) 1992-09-09
DE59204217D1 (de) 1995-12-14
JPH04354007A (ja) 1992-12-08

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