WO1998003325A1 - Thermoforming method using a free flat parison - Google Patents

Thermoforming method using a free flat parison Download PDF

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Publication number
WO1998003325A1
WO1998003325A1 PCT/FR1997/001319 FR9701319W WO9803325A1 WO 1998003325 A1 WO1998003325 A1 WO 1998003325A1 FR 9701319 W FR9701319 W FR 9701319W WO 9803325 A1 WO9803325 A1 WO 9803325A1
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WO
WIPO (PCT)
Prior art keywords
mold
parison
flat
molding
flat parison
Prior art date
Application number
PCT/FR1997/001319
Other languages
French (fr)
Inventor
Hervé Duplessy
Original Assignee
Duplessy Herve
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 Duplessy Herve filed Critical Duplessy Herve
Priority to EP97934572A priority Critical patent/EP0920372A1/en
Priority to AU37730/97A priority patent/AU3773097A/en
Publication of WO1998003325A1 publication Critical patent/WO1998003325A1/en

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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
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/26—Component parts, details or accessories; Auxiliary operations
    • B29C51/30—Moulds
    • B29C51/32—Moulds having cutting means
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • 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
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/02—Combined thermoforming and manufacture of the preform
    • 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
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/26—Component parts, details or accessories; Auxiliary operations
    • B29C51/261—Handling means, e.g. transfer means, feeding means
    • 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
    • B29C2791/00—Shaping characteristics in general
    • B29C2791/004—Shaping under special conditions
    • B29C2791/006—Using vacuum
    • 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
    • B29C2793/00—Shaping techniques involving a cutting or machining operation
    • B29C2793/0081—Shaping techniques involving a cutting or machining operation before shaping
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • 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
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/10—Forming by pressure difference, e.g. vacuum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
    • B29K2027/06—PVC, i.e. polyvinylchloride

Definitions

  • the traditional method ermo- t ormage uses a cycle f roid for performing pieces formed of a thin wall; an e :: extruder comprising a flat die continuously manufactures a strip of plastic material, with a thickness ranging from a fraction of a millimeter. ten millimeters and a width determined by that of the sector; this strip of thermo-plastic material is generally calendered between rollers :: at the outlet of the machine, to adjust the thickness thereof, while it is still plastic then it is cooled and cut into standard size sheets.
  • these plates are optionally cut again according to the characteristics of the shape to be coated; they are reheated, generally by panels :: radiant radiant in 1 î nf ra-r ouge then introduced ua ⁇ s the mold; the mold generally consists of a horizontal joint plane placed at its upper part, the shape to be molded being in a cavity placed below the joint plane; the plate is pinched on the joint plane of the mold so as to create a sealed volume with the mold cavity; the molding is generally done by placing the cavity thus closed in depression, while the plate comes to marry by creep, under the action of atmospheric pressure, the shape of the bottom of the oule cavity.
  • thermoforming When it comes to manufacturing large series of small parts, such as small Swiss jars, skin-formed from thin sheets, a hot cycle thermoforming is used; the sheet is continuously extruded slipped on a horizontal carpet; the leaf is pinched laterally by pins which connect it to two: lateral drive chains which accompany it throughout the cycle; it is conditonnée temperature while the side chains on the lead a chain î mobile did horizontal multiple molds where it is molded as indicated here above pre; the separation of thermoformed objects only takes place on the finished part.
  • Large series of large parts are
  • SUBSTITUTE SHEET ⁇ RULE 26 made, in the hot cycle from an extruded sheet held laterally by a raiting chain as in the previous example; the mold is moved back and forth accompanying the movement of the sheet in the molding phase and, after demolding, returning to position upstream at a new portion of thermoform sheet; part separation is only done at the end of the cycle.
  • blowing extrusion technique for the manufacture of hollow bodies: in thin walls such as bottles using a hot tube; it consists in extruding a tube ically. forming what is called a free parison the length of which is pinched in the joint plane of a mold and separated from the upstream part of the parison; the mold is retracted and the tube is then inflated with compressed air to allow the tube to marry, by creep under air pressure, the shape of each half mold in order to thus form a hollow body with thin wall; during this time the extruder extrudes the free parison length necessary for molding the next part.
  • thermoforming technique which uses a cold cycle requires heavy means of extruding the plates which must be of great precision to allow the calendering which is itself imposed to allow uniform heating of the plate.
  • the handling of the plates, their cutting and their reheating generate additional processing costs which generally lead to the abandonment of this technique for large series.
  • Large series using the hot cycle require heavy mobile molding equipment.
  • the ob j e and the invention is to combine the advantages of both techniques, extrusion blow molding and thermoforming, to produce parts the mo-formed wall thin in hot cycle.
  • Fig.1 shows an exploded perspective view of the device according to the invention open molding device.
  • the F ⁇ g.2 represents a perspective view of the device of the F ⁇ g.1 with the closed and retracted molding device.
  • Fig.3 shows a perspective view of the mold part of the molding device according to a preferred version of the invention.
  • the F ⁇ g.4 represents a perspective view of the part against the mold of the molding device.
  • the F ⁇ g.5 to 9 show in section of the molding device the various phases of the thermoforming cycle according to a preferred version of the invention.
  • the F ⁇ .10 rep és n e an erspective view of the extrusion device of the flat parison according to a preferred version of the invention.
  • FIG. 16 represents an exploded perspective view of a device for cutting the thermoformed part during cycle.
  • the invention consists in extruding vertically from a flat die (1) a length of a strip of thin plastic material, which will be called hereinafter "flat parison ( 2) ", to condition it at temperature, and to introduce it into a thermoforming device (7) formed by a mold ( 3 ) and a counter mold (4) which clamps a length of flat parison ( 2) in its joint plane (5) which is in a vertical position, to separate it from the upstream part ( 6 ) of the flat parison (2) located between the molding device ( 7 ) and the die ⁇ 1>, to retract the molding device ( 7 ) F ⁇ g.2 in order to carry out the thermoforming of the part; meanwhile the flat die (1) extrudes a flat parison length (2) sufficient for the rmo-f form the next part.
  • the thermoforming device comprises a mold f ⁇ g.3 which is composed of two. parts; the first part consists of a frame (10) supporting the joint plane (13) and the second part constitutes the impression (11) of the form (14 ) to be molded; the frame (10) and the imprint (11) slide relative to each other by means of guide columns (12).
  • a blade ( 21 ) F ⁇ g.3 is fixed on the imprint so • _.
  • the counter mold F ⁇ g.4 and (4) F ⁇ g.5 comprises a cavity (19) bordered by a joint plane (20) which comes to apply F ⁇ g.6 on the joint plane (13) of the frame (10) of the mold (3) in order to pinch the flat parison (16); this cavity (19) is deep enough to contain the volumes which exceed the joint plane when the molding device is closed: in a preferred version of the invention, the cavity (11) is provided with vents for evacuation air contained between the flat parison (16) and the cavity (11); when the molding device is closed on a flat parison (16) F ⁇ g.7 compressed air is injected into the cavity (19) F ⁇ g.8 of the counter mold (4) as we do to blow a bottle and we plate the flat parison ( 16 ) on the form (18) the imprint (11); the mold carriers having closing pressures of several tonnes, this makes it possible to use compressed air pressures of several bars and to obtain a very good surface quality of the part ( 24 ) F ⁇ g.9 thus the mo- formed.
  • the version of the invention which we have just described can be suitable for amorphous thermo-plastic materials such as polyethylenes or ⁇ o lych 1 o rural vinyls; it can allow the use of existing blow molding machines without major modifications; however, the process is not suitable for thermoforming of so-called crystalline thermoplastic materials, the viscosity of which drops very rapidly as a function of the temperature in the temperature zone co res undulating at the extrusion temperature.
  • this problem is solved by extruding the material continuously on a movable belt (preferably 25 ⁇ horizontal which moves at substantially constant speed relative to the die).
  • the material is conditioned in temperature, by a temperature conditioning device (28). to bring it to a temperature where the internal friction between the molecules is sufficient to slow the creep.
  • a temperature conditioning device 28
  • the material can be extruded between 200 and 300 degrees centigrade and brought to the moving belt ( 25 ) at a temperature of the order of 80 to 100 degrees centigrade which may correspond to what is called for certain materials the caout zone chout i que and which reduces the time of cycle.
  • the flat parison (27 ) At the end of the moving belt, the flat parison (27 )
  • Fig. 11 hangs in a vacuum to be able to be taken between the mold ( 3 ) and the counter mold (4) when it has reached a sufficient length as described above.
  • One way of achieving synchronization between the movements of the moving belt (25) and the movements of the extruder ( 30 ) is to use a synchronous motor to drive the drum motor (32) of the moving belt (25); a link chain ( 33 ) in closed loop is driven by a pinion ( 34 ) , integral with the motor drum (32) of the moving belt ( 25 ) , at the same
  • the speed of the motorized wheels (35) can be slightly modulated during the cycle to vary the thickness of the flat parison (27 ⁇
  • a molding device which remains in place once it is closed since the e - 1 seamer ( 30 ) deposits the material on the movable belt (25) which is immobilized then introduces it between the mold (3) Fj.13 and the con r - oule (4; lo sque the molding device ( "is open and the previous part (36) F ⁇ g.11 gée.
  • the counter mold (3) F ⁇ g.4 has a cavity (19) inside which it is possible to place one or more cutting devices F ⁇ g.16 allowing the cutting of elements of the thermoformed part and working in the atmosphere of the thermoforming air pressure; a cutting device comprises a cutting tool (37) and an operating device (38) thereof; without this example being limiting, the operating device (38) can be made up of one or more preferably hydraulic jacks which apply the cutting tool (37) to the area to be cut at the same time as the material is applied to the shape of the impression by air pressure.
  • the force necessary to ensure a good cut is several 1- lonewtons per centimeter of cut added to the gas pressure in the counter-mold which can be of the order of 8 to 10 bars can impose closing forces.
  • the temperature of the material can be regulated by natural cooling and or by forced convection with the aid of a temperature conditioning device (28); when using fans it is preferable to fix the temperature conditioning device (28) to the frame (31) of the extruder so that whatever the movements of the moving belt (25) are cooling in forced convection remains essentially the same.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)

Abstract

A method wherein a flat parison (2) is extruded using a flat die (1) in such a way that it hangs freely either at the extruder outlet or following a heat treatment, and the parison is squeezed in a moulding device (7) consisting of a mould (3) and a matching opposite mould (4) with a vertical land (5), and separated by a cutting means for cutting the upper portion (6) of the flat parison. Thermoforming is preferably carried out by injecting compressed air into the opposite mould cavity after retracting the moulding device.

Description

PROCEDE DE THERMO-FORMAGE UTILISANT UNE PARAISON PLATE LIBRE THERMOFORMING PROCESS USING FREE FLAT PARISON
Le procédé de t ermo- ormage traditionnel utilise un cycle froid permettant de réaliser des pièces formées d'une paroi mince; une e::trudeuse comportant une filière plate fabrique en continu une bande de matière plastique, d'une épaisseur allant d'une fraction de millimètre -_. la dizaine de millimètre et d'une largeur déterminée par celle de la filière; cette bande de matière thermo-plasti ue est généralement calandrée entre des rouleau:: à la sortie de 1 ' e::t r udeuse , pour en ajuster au mieu- l'épaisseur, alors qu'elle est encore plastique puis elle est refroidie et découpée en plaques de dimension standard. Lors de la mise en oeuvre de ces plaques pour les thermo-forme r , elles sont éventuell ment découpées une nouvelle fois en fon tion des caractéristi ues de la forme à ouler; elles sont réchauffées, généralement par des panneau:: radiants rayonnant dans 1 ' î n f ra-r ouge puis introduite uaπs le moule; le moule est généralement constitué d'un plan de joint horizontal placé à sa partie supérieure la forme à mouler étant dans une cavité placée en dessous du plan de joint; la plaque est pincée sur le plan de joint du moule de manière à créer avec la cavité du moule un volume étanche; le moulage se fait généralement par mise en dépression de la cavité ainsi fermée, tandis que la plaque vient épouser par fluage, sous l'action de la pression at osphérique, la for e du fond de la cavité du oule. Lorsqu'il s'a it de fabriquer de grandes séries de petites pièces, telles que les pots de petit suisse, t ermo-formées à partir de feuilles minces, on emploie un thermo-fo mage à cycle chaud; la feuille est e::trudée en continu glissé sur un tapis horizontal; la feuille est pincée latéralement par des picots qui la relient à deu:; chaînes d'entraînement latérales qui l'accompagnent pendant tout le cycle; elle est conditonnée en température tandis que les chaînes latérales l'amènent sur une chaîne mobile a moules multiples horizontale où elle est moulée comme indiqué pré édemment; la séparation des objets thermo-formés n'intervient que sur la pièce terminée. Les grandes séries de pièces de grande dimension sontThe traditional method ermo- t ormage uses a cycle f roid for performing pieces formed of a thin wall; an e :: extruder comprising a flat die continuously manufactures a strip of plastic material, with a thickness ranging from a fraction of a millimeter. ten millimeters and a width determined by that of the sector; this strip of thermo-plastic material is generally calendered between rollers :: at the outlet of the machine, to adjust the thickness thereof, while it is still plastic then it is cooled and cut into standard size sheets. During the implementation of these plates for thermoforms r, they are optionally cut again according to the characteristics of the shape to be coated; they are reheated, generally by panels :: radiant radiant in 1 î nf ra-r ouge then introduced uaπs the mold; the mold generally consists of a horizontal joint plane placed at its upper part, the shape to be molded being in a cavity placed below the joint plane; the plate is pinched on the joint plane of the mold so as to create a sealed volume with the mold cavity; the molding is generally done by placing the cavity thus closed in depression, while the plate comes to marry by creep, under the action of atmospheric pressure, the shape of the bottom of the oule cavity. When it comes to manufacturing large series of small parts, such as small Swiss jars, skin-formed from thin sheets, a hot cycle thermoforming is used; the sheet is continuously extruded slipped on a horizontal carpet; the leaf is pinched laterally by pins which connect it to two: lateral drive chains which accompany it throughout the cycle; it is conditonnée temperature while the side chains on the lead a chain î mobile did horizontal multiple molds where it is molded as indicated here above pre; the separation of thermoformed objects only takes place on the finished part. Large series of large parts are
FEUILLE DE REMPLACEMENT {REGLE 26) réalisées, en cycle chaud à partir d'une feuille extrudée tenue latéralement par une chaîne d'en raî ement comme dans l'exemple précédent; le moule est animé d'un mouvement va et vient accompagnant le déplacement de la feuille en phase de moulage et, après démoulage, revenant se positionner en amont au niveau d'une nouvelle portion de feuille à thermo- orme ; la séparation de la pièce ne se fait qu'en fin de cycle.SUBSTITUTE SHEET {RULE 26) made, in the hot cycle from an extruded sheet held laterally by a raiting chain as in the previous example; the mold is moved back and forth accompanying the movement of the sheet in the molding phase and, after demolding, returning to position upstream at a new portion of thermoform sheet; part separation is only done at the end of the cycle.
Il existe d'autre part la technique d'extrusion soufflage pour la fabrication de corps creu: en parois minces tels que des bouteilles utilisant u ycle chaud; elle consiste à extruder e icalement un tube. fo mant ce que l'on appelle une paraison libre dont une longueur est pincée dans le plan de joint d'un moule et séparée de la partie amont de la paraison; le moule est escamoté et le tube est ensuite gonflé à l'air comprimé pour permettre au tube de venir épouser, par fluage sous la pression de l'air, la forme de chaque demi moule afin de Former ainsi un corps creux a paroi mince; pendant ce temps l'extrudeuse extrude la longueur de paraison libre nécessaire au moulage de la pièce sui vante .There is also the blowing extrusion technique for the manufacture of hollow bodies: in thin walls such as bottles using a hot tube; it consists in extruding a tube ically. forming what is called a free parison the length of which is pinched in the joint plane of a mold and separated from the upstream part of the parison; the mold is retracted and the tube is then inflated with compressed air to allow the tube to marry, by creep under air pressure, the shape of each half mold in order to thus form a hollow body with thin wall; during this time the extruder extrudes the free parison length necessary for molding the next part.
La technique de thermo- ormage qui utilise un cycle froid exige des moyens lourds d'extrusion des plaques qui doivent être de grande précision pour permettre le calandrage qui est lui-même imposé pour permettre un réchauffage uniforme de la plaque. La manutention des plaques leur découpe leur réchauffage engendrent des surco ts de transformation qui conduisent gén ralement à l'abandon de cette technique pour les grandes séries. Les grandes séries qui emploient le cycle chaud nécessitent un matériel lourd de moulage mobile.The thermoforming technique which uses a cold cycle requires heavy means of extruding the plates which must be of great precision to allow the calendering which is itself imposed to allow uniform heating of the plate. The handling of the plates, their cutting and their reheating generate additional processing costs which generally lead to the abandonment of this technique for large series. Large series using the hot cycle require heavy mobile molding equipment.
La technique de d'extrusion soufflage à paraison tabulaire libre ne permet pas en général de réaliser les formes qui peuvent tre obtenues par thermo-formage, notamment parce plus on s'éloigne d'une forme de révolution plus il est difficile de maîtriser la bonne répartition des épaisseurs de matières: en contre-partie elle permet de travailler en cycle chaud.The technique of extrusion blow molding with free tabular parison does not generally make it possible to produce the shapes which can be obtained by thermoforming, in particular because the more one moves away from a form of revolution the more it is difficult to control the good distribution of material thicknesses: in return it allows working in the hot cycle.
L'objet de l'invention est de concilier les avantages de ces deux techniques, d'extrusion soufflage et de thermo-formage, afin de pouvoir réaliser des pièces the mo-formées à paroi minces en cycle chaud.The ob j e and the invention is to combine the advantages of both techniques, extrusion blow molding and thermoforming, to produce parts the mo-formed wall thin in hot cycle.
La Fig.1 représente une vue perspective éclatée du dispositif selon l'invention dispositif de moulage ouvert. La Fιg.2 représente une vue perspective du dispositif de la Fιg.1 avec le dispositif de moulage fermé et escamoté.Fig.1 shows an exploded perspective view of the device according to the invention open molding device. The Fιg.2 represents a perspective view of the device of the Fιg.1 with the closed and retracted molding device.
La Fig.3 représente une vue perspective de la partie moule du dispositif de moulage selon une version préférée de 1 ' i nvent ion. La Fιg.4 représente une vue perspective de la partie contre moule du dispositif de moulage.Fig.3 shows a perspective view of the mold part of the molding device according to a preferred version of the invention. The Fιg.4 represents a perspective view of the part against the mold of the molding device.
La Fιg.5 à 9 représentent en coupe du dispositif de moulage les diverses phases du cycle de thermo-formage suivant une version préférée de l'invention. La Fι .10 rep és n e une vue erspective du dispositif d'extrusion de la paraison plate suivant une version préférée de l'inven ion.The Fιg.5 to 9 show in section of the molding device the various phases of the thermoforming cycle according to a preferred version of the invention. The Fι .10 rep és n e an erspective view of the extrusion device of the flat parison according to a preferred version of the invention.
Les Fιg. 1 à 15 représentent les diverses phases du cycles d'extrusion correspondant au cycle de thermo- ormage des Fιg.5 à 9. La Fig.16 représente une vue perspective éclatée d'un dispositif de découpe de la pièce thermo-formée en cours de cycle .The Fιg. 1 to 15 represent the various phases of the extrusion cycles corresponding to the thermoforming cycle of FIGS. 5 to 9. FIG. 16 represents an exploded perspective view of a device for cutting the thermoformed part during cycle.
D'une manière générale l'invention consiste à extruder verti alement à partir d'une filière plate (1) une longueur d'une bande de matière the mo-plastique de faible épaisseur, qu'on apellera ci-après "paraison plate (2)", de la conditionner en température, et de l'introduire dans un dispositif de thermo-formage (7) formé d'un moule (3) et d'un contre moule (4) qu pince une longueur de paraison plate (2) dans son plan- de joint (5) qui est en position verticale , de la séparer de la partie amont (6) de la paraison plate (2) située entre le dispositif de moulage (7) et la filière <1>, d'escamoter le dispositif de moulage (7) Fιg.2 afin d'effectuer le thermo-formage de la pièce; pendant ce temps la filière plate (1) extrude une longueur de paraison plate (2) suffisante pour the rmo-f orme la pièce suivante .In general, the invention consists in extruding vertically from a flat die (1) a length of a strip of thin plastic material, which will be called hereinafter "flat parison ( 2) ", to condition it at temperature, and to introduce it into a thermoforming device (7) formed by a mold ( 3 ) and a counter mold (4) which clamps a length of flat parison ( 2) in its joint plane (5) which is in a vertical position, to separate it from the upstream part ( 6 ) of the flat parison (2) located between the molding device ( 7 ) and the die <1>, to retract the molding device ( 7 ) Fιg.2 in order to carry out the thermoforming of the part; meanwhile the flat die (1) extrudes a flat parison length (2) sufficient for the rmo-f form the next part.
A titre d'exemple, sans que cet exemple soit limitatif, on peut partir d'une machine d'extrusion soufflage classique à paraison libre et comportant un porte moule escamotable; on remplace la t te d'extrusion par une filière plate M) Fιg.1, et on place dans le porte moule escamotable un dispositif de thermo- ormage (7) formé d'un moule (3) fixé sur un des plateaux du porte moule et d'un contre moule (4) fixé sur l'autre plateau; le plan de joint (5) du moule (3) et du contre moule (4) est placé verticalement parallèlement au plan de la paraison plate (2) en cours d'extrusion; une paraison plate (2; de longueur suffisante étant extrudée, on place le porte moule, en position ouverte, de manière à ce que la paraison plate soit placée entre le moule (3) et le contre moule (4); en fermant le porte moule on pince la paraison plate (2) dans le plan de joint (5) situé entre le moule (3) et le contre moule (4) de manière à former une enceinte fermée (?) avec la paroi interne formant la cavité (8) du moule (3); on coupe la paraison plate (2) par un moyen ( 17) approprié connu manoeuvré par exemple par un vérin hydraulique (39); et on escamote le porte moule pour permettre à l'extrudeuse de continuer l'extrusion de la paraison plate (2) Fιg.2 pour la pièce suivante. Pendant ce temps il suffit par exemple d'aspirer l'air de l'enceinte (9) comme décrit précédemment pour obtenir la pièce désirée. Le porte-moule est ensuite ouvert, séparant le moule (3) du contre moule (4) et la pièce évacuée puis le porte moule se représente comme décrit précédemment au niveau de la paraison plate (2) qui a la longueur voulue pour entamer un nouveau cycle.By way of example, without this example being limiting, it is possible to start from a conventional blow molding extrusion machine with free parison and comprising a retractable mold holder; we replaces t you to extrusion through a flat die M) Fιg.1, and placed in the mold carries a retractable d i spositif of thermoplastic ormage (7) formed of a mold (3) fixed on one of the plates mold holder and a counter mold (4) fixed on the other plate; the joint plane (5) of the mold (3) and of the counter mold ( 4 ) is placed vertically parallel to the plane of the flat parison (2) during extrusion; a flat parison (2; of sufficient length being extruded, the mold holder is placed in the open position, so that the flat parison is placed between the mold (3) and the counter mold (4); closing the door mold the flat parison (2) is clamped in the joint plane (5) located between the mold (3) and the counter mold (4) so as to form a closed enclosure (?) with the internal wall forming the cavity ( 8 ) of the mold (3); the flat parison (2) is cut by a suitable means (17) known, operated for example by a hydraulic cylinder (39); and the mold holder is retracted to allow the extruder to continue the extrusion of the flat parison (2) Fιg.2 for the next part. During this time it suffices for example to suck the air from the enclosure (9) as described above to obtain the desired part. then open, separating the mold (3) from the counter mold (4) and the part removed, then the mold holder is represented as described above. cédemment at the level of the flat parison (2) which has the length wanted to start a new cycle.
Dans une version préférée de l'invention, le dispositif de thermo- ormage comporte un moule fιg.3 qui est composé de deux. parties; la première partie est composée d'un cadre (10) supportant le plan de joint (13) et la deuxième partie constitue l'empreinte (11) de la forme (14) à mouler; le cadre (10) et l'empreinte (11) coulissent l'un par rapport à l'autre grâce à des colonnes de guidage (12). Une lame (21) Fιg.3 est fixée sur l'empreinte de manière •_. ne pas g ner le débattement du cadre (10) sur le partie supérieure duquel elle est appuyée; l'ar te coupante (22) de la lame (21) qui est parallèle au plan de joint (13) et en retrait par rapport à ce dernier a une longueur supérieure à la largeur de la paraison plate; le fil (22) de la lame (21) peut Ptre mis de biais lorsque le procédé d'extrusion permet d'arrêterIn a preferred version of the invention, the thermoforming device comprises a mold fιg.3 which is composed of two. parts; the first part consists of a frame (10) supporting the joint plane (13) and the second part constitutes the impression (11) of the form (14 ) to be molded; the frame (10) and the imprint (11) slide relative to each other by means of guide columns (12). A blade ( 21 ) Fιg.3 is fixed on the imprint so • _. do not interfere with the travel of the frame (10) on the upper part of which it is supported; Ar cutting te (22) of the blade (21) which is parallel to the joint plane (13) and recessed with respect to d ernier has a length greater than the width of the flat parison; the wire (22) of the blade ( 21 ) can be put at an angle when the extrusion process makes it possible to stop
FEUILLE DE REMPLACEMENT (FÈGLE 26) le défilement de la paraison le temps de la coupe. Lorsque le dispositif de moulage est ouvert l'empreinte (11) est escamotée par rapport au cadre (10); ceci permet à l'empreinte (11) de comporter des volumes maies qui ne gênent pas le positionnement de la paraison plate lorsque le dispositif de moulage est ouvert et qui dépassent le plan de joint (13) lorsque le dispositif de moulage est fermé; l'empreinte (11) est maintenue escamotée par un dispositif élastique qui peut tre par exemple, sans que cet exemple soit li itatif, composé de ressorts (15): lorsque le dispositif de moulage se ferme le plan de joint, formé par le contact du cadre (10) Fιg.5 et du contre moule (4), se ferme Fιg.6 sur la paraison plate ( 16) de manière à la tenir tendue puis l' reinte (11) Fιg.7 prend sa place par rapport au cadre ( 10) par coulissement sur les colonnes de guidage ' 12) Fιg.3 et compression du système élastique (15); dans le même temps la l'arête (22) de la lame (21) traverse le plan de joint (13) et sépare la paraison plate (23) Fιg.6 de la pièce suivante du dispositif de moulage Fιg.7; en cours de mouvement certains volumes de la forme (18) Fιg.7 de l'empreinte peuvent traverser le plan de joint (13), la paraison plate (16) venant s'appliquer sur leur surface. Le contre moule Fιg.4 et (4) Fιg.5 comporte une cavité (19) bordée par un plan de joint (20) qui vient s'appliquer Fιg.6 sur le plan de joint (13) du cadre (10) du moule (3) afin de pincer la paraison plate (16); cette cavité (19) est suffisamment profonde pour contenir les volumes qui dépassent le plan de joint lorsque le dispositif de moulage est fermé: dans une version préférée de l'invention, l'empreinte (11) est munie d'évents pour l'évacuation de l'air contenu entre la paraison plate (16) et l'empreinte (11); lorsque le dispositif de moulage est fermé sur une paraison plate (16) Fιg.7 on injecte de l'air comprimé dans la cavité (19) Fιg.8 du contre moule (4) comme on le fait pour souffler un flacon et on plaque la paraison plate (16) sur la forme (18) l'empreinte (11); les porte moules ayant des pressions de fermeture de plusieurs tonnes, cela permet d'utilis r des pressions d'air comprimé de plusieurs bars et d'obtenir une très bonne qualité de surface de la pièce (24) Fιg.9 ainsi the mo-formée.SUBSTITUTE SHEET (FAGLE 26) the scrolling of the parison the time of the cut. When the molding device is open, the impression (11) is retracted with respect to the frame (10); this allows the cavity (11) to have well-formed volumes which do not interfere with the positioning of the flat parison when the molding device is open and which protrude beyond the joint plane (13) when the molding device is closed; the imprint (11) is kept retracted by an elastic device which can be for example, without this example being binding, composed of springs (15 ) : when the molding device closes the joint plane formed by the contact of the frame (10) Fιg.5 and of the counter mold (4), closes Fιg.6 on the flat parison (16) so as to keep it taut, then the retouch (11) Fιg.7 takes its place relative to the frame (10) by sliding on the guide columns' 12) Fιg.3 and compression of the elastic system (15); at the same time the edge (22) of the blade (21) crosses the joint plane (13) and separates the flat parison (23) Fιg.6 from the next part of the molding device Fιg.7; during movement certain volumes of the shape (18) Fιg.7 of the imprint can cross the joint plane (13), the flat parison (16) coming to be applied on their surface. The counter mold Fιg.4 and (4) Fιg.5 comprises a cavity (19) bordered by a joint plane (20) which comes to apply Fιg.6 on the joint plane (13) of the frame (10) of the mold (3) in order to pinch the flat parison (16); this cavity (19) is deep enough to contain the volumes which exceed the joint plane when the molding device is closed: in a preferred version of the invention, the cavity (11) is provided with vents for evacuation air contained between the flat parison (16) and the cavity (11); when the molding device is closed on a flat parison (16) Fιg.7 compressed air is injected into the cavity (19) Fιg.8 of the counter mold (4) as we do to blow a bottle and we plate the flat parison ( 16 ) on the form (18) the imprint (11); the mold carriers having closing pressures of several tonnes, this makes it possible to use compressed air pressures of several bars and to obtain a very good surface quality of the part ( 24 ) Fιg.9 thus the mo- formed.
QUILLE DE REMPLACEMENT (REGLE 26) L'extrusion d'une paraison plate (2) Fιg.1 libre suppose que la matière employée ait, à la température d'extrusion, une viscosité cohérente avec la longueur de matière à extruder, pour constituer la longueur de paraison plate (2) nécessaire et le temps de cycle de la machine; en effet si la paraison plate est trop longue ou si elle reste suspendue trop longtemps, il se produit du fluage qui amincit la paraison plate (2) dans la partie haute et nuit à la qualité du produit obtenu. Une manière de procéder, pour éviter le fluage, consiste à stocl-er la matière plastifiée en bout de vis de plastification comme cela se fait couramment en injection et à extruder la paraison plate (2) à l'aide d'un vérin au moment de l'introduire dans le dispositif de moulage (7) ouvert; cette technique peut manquer de fiabilité car lorsqu'on interrompt le flux de matière dans une filière sa température change et agit sur la fluidité de la matière. La version de l'invention que nous venons de décrire peut convenir aux matières thermo-plastiques amorphes telles que des polyé thyl ènes ou des ρo lych 1 o rur es de vinyles; elle peut permettre d'utiliser des machines d'extrusion soufflage existantes sans modifi ations majeures; cependant le procédé ne convient pas au thermo-formage des matières thermo-plasti ues dites cristallines dont la viscosité chute très rapidement en fonction de la température dans la zone de température co res ondant à la température d'extrusion. Dans la version préférée de l'invention, on résout ce problème en extrudant la matière en continu sur un tapis mobile ( 25 ^ de préférence horizontal qui se déplace à vitesse sensiblement constante par rapport à la filièreREPLACEMENT Keel (RULE 26) The extrusion of a flat parison (2) free Fιg.1 assumed that the material used has, at the extrusion temperature, i v scosité consistent with the length of material to be extruded, to form the flat length of parison ( 2) necessary and cycle time of the machine; indeed if the flat parison is too long or if it remains suspended too long, creep occurs which thins the flat parison ( 2 ) in the upper part and harms the quality of the product obtained. One way of proceeding, to avoid creep, consists in stocl-er the plasticized material at the end of the plasticizing screw as is commonly done in injection and in extruding the flat parison (2) using a jack at the time introduce it into the open molding device (7); this technique can lack reliability because when the flow of material is interrupted in a die its temperature changes and affects the fluidity of the material. The version of the invention which we have just described can be suitable for amorphous thermo-plastic materials such as polyethylenes or ρo lych 1 o rural vinyls; it can allow the use of existing blow molding machines without major modifications; however, the process is not suitable for thermoforming of so-called crystalline thermoplastic materials, the viscosity of which drops very rapidly as a function of the temperature in the temperature zone co res undulating at the extrusion temperature. In the preferred version of the invention, this problem is solved by extruding the material continuously on a movable belt (preferably 25 ^ horizontal which moves at substantially constant speed relative to the die).
(26); pendant son passage sur le tapis mobile (25) la matière est conditionnée en température, par un dispositif de conditonnement en température (28). pour l'amener à une température où les frottements internes entre les molécules sont suffisants pour ralentir le fluage. A titre d'exemple non limitatif la matière peut tre extrudée entre 200 et 300 degrés centigrades et ramenée sur le tapis mobile (25) à une température de l'ordre de 80 à 100 degrés centigrades ce qui peut correspondre à ce qu'on appelle pour certaines matières la zone caout chout i que et ce qui réduit d'autant le temps de cycle. En bout du tapis mobile la paraison plate (27) (26); during its passage on the moving belt ( 25 ) the material is conditioned in temperature, by a temperature conditioning device (28). to bring it to a temperature where the internal friction between the molecules is sufficient to slow the creep. By way of nonlimiting example, the material can be extruded between 200 and 300 degrees centigrade and brought to the moving belt ( 25 ) at a temperature of the order of 80 to 100 degrees centigrade which may correspond to what is called for certain materials the caout zone chout i que and which reduces the time of cycle. At the end of the moving belt, the flat parison (27 )
Fig.11 pend dans le vide pour pouvoir tre prise entre le moule (3) et le contre moule (4) lorsqu'elle a atteint une longueur suffisante comme on l'a décrit précédemment.Fig. 11 hangs in a vacuum to be able to be taken between the mold ( 3 ) and the counter mold (4) when it has reached a sufficient length as described above.
Dans une variante de la version préférée de l'invention, la filière plate (26) Fιg.11 dépose sur le tapis mobile (25) une longueur de paraison plate (27) suffisante pour l'introduire dans le dispositif de moulage (7); lorsque le dispositif de oulage (7) est en esure de recevoir la paraison plate (27), le tapis mobile (25) Fιg.12 se met en mouv ent pour faire escendr entre le moule (3) et le contre-mouïe (4) une longueur de paraison plate (27) Fιg.13 suffisante, le dispo.itif de oulage (7) F i g .1 se fe me sur la μa raison p I i te (27) et la lame (21) solidaire de l'e ein e (11) moule ≤ectiαnne l=ι parai son plate (27) tandis que le ta is mobile ( 25 ) F i .15 revient l gère nt en arrière pour ramener le bout (29) de paraison plate (25) située entre le tapis mobile (25) et le dispositif de moulage (7) sur la partie horizontale du tapis mobile (25) et ce dernier s'immobilise jusqu'au début du cycle suivant; pendant ce temps l'extrudeuse (30) Fιg.10 qui est montée sur un châssis mobile (31), par rapport au châssis supportant le ou les dispositifs de moulages (7) ainsi que par rapport au châssis supportant le tapis mobile (25), se déplace à une vitesse contrôlée par rapport à la surface du tapis mobile (25) et en sens contraire du sens d'avancée du tapis mobile (25), pour déposer en continu une paraison plate (27) d' aisseur connue de matière t her o- plastique sur le tapis mobile (25); en général l'épaisseur de matière déposée sur le tapis est constante -mais on peut moduler la vitesse de déplacement de 1 ' ex r udeuse (30) par rapport à la surface du tapis mobile (25) pour en modifier l'épaisseur en certains endroits pour compenser des effets dus au fluage ou si la configuration de la pièce à fabriquer l'exige. Une manière de réaliser la synchronisation entre les mouvements du tapis mobile (25) et les mouvements de l'extrudeuse (30) est d'utiliser un moteur synchrone pour entraîner le tambour moteur (32) du tapis mobile (25); une chaîne a maillons (33) en boucle fermée est entraînée par un pignon (34), solidaire du tambour moteur (32) du tapis mobile (25), à la mêmeIn a variant of the preferred version of the invention, the flat die ( 26 ) Fιg.11 deposits on the movable belt (25) a length of flat parison (27) sufficient to introduce it into the molding device (7) ; when the oulage device (7) is in esure to receive the flat parison (27), the movable belt (25) Fιg.12 starts to move to make it descend between the mold (3) and the counter-mold (4 ) a sufficient length of flat parison (27) Fιg.13, the curling device (7) F ig .1 is fe me on the μa reason p I i te (27) and the blade (21) integral with the 'e ein e (11) mold ≤ectiαnne l = ai appears its flat (27) while the ta is mobile (25) F i .15 returns l manages nt back to bring back the end (29) of flat parison (25 ) located between the moving belt (25) and the molding device (7) on the horizontal part of the moving belt (25) and the latter stops until the start of the next cycle; meanwhile the extruder (30) Fιg.10 which is mounted on a movable frame (31), relative to the frame supporting the molding device (s) (7) as well as relative to the frame supporting the movable belt (25) , moves at a controlled speed relative to the surface of the moving belt (25) and in the opposite direction to the direction of advancement of the moving belt (25), to continuously deposit a flat parison (27) of a known known material t her o- plastic on the moving belt (25); in general the thickness of material deposited on the carpet is constant - but one can modulate the speed of movement of one ex r uder (30) relative to the surface of the moving carpet (25) to modify the thickness in certain places to compensate for effects due to creep or if the configuration of the workpiece requires it. One way of achieving synchronization between the movements of the moving belt (25) and the movements of the extruder ( 30 ) is to use a synchronous motor to drive the drum motor (32) of the moving belt (25); a link chain ( 33 ) in closed loop is driven by a pinion ( 34 ) , integral with the motor drum (32) of the moving belt ( 25 ) , at the same
FEUILLE DE REMPLACEMENT (RÈGLE 26) vitesse linéaire que le tapis mobile (25); le brin de la chaîne à maillon (33) qui se déplace dans le sens du tapιs mobile (25) supporte le châssis mobile (31) de l'extrudeuse (30) par l'int rmédiaire de roue motorisée (35) tournant à vitesse constante dans le sens opposé au sens de déplacement général du tapis mobile (25). Comme nous l'avons expliqué précédemment la vitesse des roues motorisées (35) peut tre légèrement modulée en cours de cycle pour faire varier l'épaisseur de la paraison plate (27^ Un tel dispositif permet notamment d'utiliser un dispositif de moulage ( "" ) qui reste en place une fois qu'il est refermé puisque 1 ' e - 1 udeuse (30) dépose la matière sur le tapis mobile (25) qui est immobilisé puis l'introduit entre le moule (3) F-j.13 et le con r - oule (4; lo sque le dispositif de moulage ( " est ouvert et la pièce précédente (36) Fιg.11 g gée .SUBSTITUTE SHEET (RULE 26) v i linear tesse that the moving belt (25); the strand of a cha î not to link (33) which moves in the direction of the i tapι s mob (25) supports the movable frame (31) of the extruder (30) by the motorized wheel int rmédiaire (35) rotating at constant tesse v i in the opposite direction to the general direction of movement of the moving belt (25). As we explained previously, the speed of the motorized wheels (35) can be slightly modulated during the cycle to vary the thickness of the flat parison (27 ^ Such a device makes it possible in particular to use a molding device ("") which remains in place once it is closed since the e - 1 seamer ( 30 ) deposits the material on the movable belt (25) which is immobilized then introduces it between the mold (3) Fj.13 and the con r - oule (4; lo sque the molding device ( "is open and the previous part (36) Fιg.11 gée.
Le contre moule (3) Fιg.4 possède une cavité (19) à l'intérieur de laquelle il est possible de placer un ou plusieurs dispositifs de découpe Fιg.16 permettant de découper des éléments de la pièce thermo-fo mée et travaillant dans l'ambiance de la pression d'air de thermo-formage ; un dispositif de découpe comporte un outil de découpe (37) et un dispositif de manoeuvre (38) de ce dernier; sans que cet exemple ait un caractère limitatif, le dispositif de manoeuvre (38) peut tre constitué d'un ou plusieurs vérins de préférence hydrauliques qui viennent appliquer l'outil de découpe (37) sur la zone à découper en même temps que la matière est appliquée sur la forme de l'empreinte par la pression de l'air. Cependant la force nécessaire pour assurer- une bonne découpe est de plusieurs 1- lonewtons par centimètre de découpe ajoutée à la pression de gaz dans le contre-moule qui peut- tre de l'ordre de 8 à 10 bars peut imposer des forces de fermeture de plusieurs centaines de t i 1 onewt ons : ceci implique, par exemple, l'u ilisation de porte moules dérivés de la technologie des pression d'injection pour les matières thermo-plasti ues. Le tapi. mobile (25) recevant la matière extrudée par la filière doit supporter des températures situées entre 200 et 300 degrés centigrades; il peut être par exemple à base de te lon afin d'éviter notamm nt à la feuille de coller des s us .The counter mold (3) Fιg.4 has a cavity (19) inside which it is possible to place one or more cutting devices Fιg.16 allowing the cutting of elements of the thermoformed part and working in the atmosphere of the thermoforming air pressure; a cutting device comprises a cutting tool (37) and an operating device (38) thereof; without this example being limiting, the operating device (38) can be made up of one or more preferably hydraulic jacks which apply the cutting tool (37) to the area to be cut at the same time as the material is applied to the shape of the impression by air pressure. However, the force necessary to ensure a good cut is several 1- lonewtons per centimeter of cut added to the gas pressure in the counter-mold which can be of the order of 8 to 10 bars can impose closing forces. several hundreds of ti 1 onewt ons: this implies, for example, the use of mold holders derived from injection pressure technology for thermo-plastic materials. The lurking. mobile (25) receiving the material extruded by the die must withstand temperatures between 200 and 300 degrees centigrade; it can for example be based on te lon to avoid notamm nt to the sheet to stick above .
La régulation de la température de la matière peut être réalisée par refroidissement naturel et ou en convection forcée à l'aide d'un dispositif de condi ionnement en températu e (28); lorsqu'on utilise des ventilateurs il est préférable de fixer le dispositif de conditionnement en température (28) au ch ssis (31) de l'extrudeuse de manière à ce que quelque soient les mouvements du tapis mobile (25) le te s de refroidissement en convection forcée reste sensiblement le même. The temperature of the material can be regulated by natural cooling and or by forced convection with the aid of a temperature conditioning device (28); when using fans it is preferable to fix the temperature conditioning device (28) to the frame (31) of the extruder so that whatever the movements of the moving belt (25) are cooling in forced convection remains essentially the same.

Claims

REVENDICATIONS 1-Procédé de thermo-formage de matière thermo-plastique en cycle chaud, à partir d'une feuille mince extrudée en bande par une filière plate (1) qui extrude en continu une paraison plate (2), qui pend verti alement et qui lorsqu'elle a atteint une longueur suffisante, est pincée par un dispositif de moulage, dont le plan de joint (5) est positionné verti alement, qui est constitué d'un moule (3) comportant une cavité (14) et d'un contre moule (4) compurtant une cavité ' 19! , caractérisé en ce que la partie de la paraison plate (2) pincée dans le moule est séparée de la partie supérieure <6) de la paraison plate (2) par des moyens de découpe (17) solidaires du moule tandis que la partie supérieure (6) de la paraison plate (2) et le dispositif de moulage (7) s'escamotent l'un par rapport à l'autre par des moyens d'escamotage associés à des moyens de stoct-age et éven uellement à des moyens de condi ionnement en température, le moule (3) pouvant comporter des moyens de découpe internes de la pièce thermo-formée. 2-Dιsρosιtιf de moulage suivant la revendication 1 caractérisé en ce que le moule est composé d'un cadre (10), supportant le plan de joint (13) de pincement de la paraison (16) contre le plan de joint (20) du contre moule (4), et d'une empreinte (11) comportant la forme (18) de la pièce à mouler, le cadre (10) et l'empreinte (11) coulissant l'un par rapport à l'autre grSrce à des colonnes (12) et des moyens élastiques (15) qui maintiennent l'empreinte (11) escamotée par rapport au cadre (10) lorsque le dispositif de moulage (7) est ouvert. 3-Dιsρoειtιf de moulage suivant la revendication 1 caractérise en ce que le moyen de découpe de la paraison plate (16) est constitué d'une lame (21) solidaire de l'empreinte (11) et .'appuyant sur la partie supérieure du cadre (10) et qui coupe la paraison (16) au moment où l'empreinte (11) prend sa place par rapport au cadre lors de la fermeture du dispositif de moulage C ) .CLAIMS 1-Thermo-forming process of thermo-plastic material in hot cycle, starting from a thin sheet extruded in strip by a flat die (1) which continuously extrudes a flat parison (2 ) , which hangs vertically and which when it has reached a sufficient length, is clamped by a molding device, the joint plane (5) of which is positioned vertically, which consists of a mold (3) comprising a cavity (14) and a counter mold (4) including a cavity '19! , characterized in that the part of the flat parison (2) pinched in the mold is separated from the upper part <6) of the flat parison (2) by cutting means (17) integral with the mold while the upper part (6) of the flat parison (2) and the molding device (7) retract one with respect to the other by retraction means associated with storage means and possibly with means temperature conditioning, the mold (3) may include internal cutting means of the thermoformed part. 2-molding description according to claim 1 characterized in that the mold is composed of a frame (10) supporting the joint plane (13) gripping the parison (16) against the joint plane (20) of the against mold (4), and an imprint (11) comprising the shape (18) of the part to be molded, the frame (10) and the imprint (11) sliding relative to one another thanks to columns (12) and elastic means (15) which hold the impression (11) retracted relative to the frame (10) when the molding device (7) is open. 3-Dιsρoειtιf molding according to claim 1 characterized in that the cutting means of the flat parison (16) consists of a blade (21 ) integral with the imprint (11) and .'pressant on the upper part of the frame (10) and which cuts the parison ( 16 ) at the moment when the imprint (11) takes its place relative to the frame when the molding device C is closed.
1- Dispositif de moulage selon la e endi ation 1. caractérise en ce que la cavité ( 1Q~l comporte au moins un dispositif de découpe de la pièce en cours de t ermo-formage comprenant un outil de dé oupe (37) ac ionné par un dispositif de manoeuvre (38).1- Molding device according to the endi ation 1. characterized in that the cavity (1 Q ~ l comprises at least one device for cutting the part during t ermo-forming comprising a die cutting tool (37) ac ered by a operating device (38).
5-Dιsρosιtιf de moulage, suivant la revendication 1, caractérisé en ce que la paraison plate (27) est extrudée en continu par des moyens d'extrusion mobiles sur un tapis mobile (25) où elle peut tre régulée en température par un dispositif de conditionnement en température (28) avant de pendre dans le vide afin d'être saisi par le dispositif de moulage (7) . 6-Dιsρosιtιf de moulage, suivant la revendica ion 5 caractérisé en e que la paraison plate (27) est d'abord stoclée sur le tapis mobile (25), qui est en position arrêtée, par la filière (26) dont l'extrudeuse (30) se déplace à vitesse constante par rapport à la surface du tapis mobile (25), puis le tap s mobile se met en mouvement pour faire pendre la paraison plate (27) ve ti alement afin de l'introduire dans le dispositif de moulage (7) en position ouverte, puis lorsque le dispositif de moulage est refermé et la paraison plate (27) coupée, en ramène l'extrémité (29) sur le tapis mobile (25) par un mouvement de déplacement inverse, puis se met en position arr tée, tandis que la filière (26) continue de déposer la paraison plate (27) sur le tapis mobile (25).5-mold molding according to claim 1, characterized in that the flat parison ( 27) is continuously extruded by movable extrusion means on a movable belt (25) where it can be temperature controlled by a device temperature conditioning (28) before hanging in a vacuum to be gripped by the molding device (7). 6-molding description, according to claim 5, characterized in that the flat parison (27 ) is first stored on the movable belt (25), which is in the stopped position, by the die (26) including the extruder (30) moves at constant speed relative to the surface of the moving belt (25), then the mobile tap s starts to move to hang the flat parison (27) ve ti ally in order to introduce it into the device molding ( 7 ) in the open position, then when the molding device is closed and the flat parison (27) cut, brings the end (29) to the moving belt (25 ) by a movement of reverse movement, then starts in the stopped position, while the die (26) continues to deposit the flat parison (27) on the moving belt (25).
7-Dιsραsιtιf de moulage suivant la revendi ation 6 caractérisé en ce que la paraison plate (27) est conditionnée en température par un dispositif de régulation en température (28) pendant la phase d'arrêt du tapis mobile ( 5) .7-Dιsραsιtιf molding according to CLAIMS ation 6 characterized in that the flat parison ( 27 ) is conditioned in temperature by a temperature regulation device (28) during the stop phase of the moving belt (5).
8-Dιsposιtιf de moulage suivant l'une quelconque des revendications 5 et h caractérise en ce que la vitesse relative de l'extrudeuse (30) par rapport au tapis mobile (25) peut être modulée au cours du cycle pour faire varier l'épaisseur de la paraison plate (27). 8-molding device according to any one of claims 5 and h characterized in that the relative speed of the extruder (30) relative to the moving belt (25) can be modulated during the cycle to vary the thickness of the flat parison ( 27 ) .
PCT/FR1997/001319 1996-07-19 1997-07-16 Thermoforming method using a free flat parison WO1998003325A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP97934572A EP0920372A1 (en) 1996-07-19 1997-07-16 Thermoforming method using a free flat parison
AU37730/97A AU3773097A (en) 1996-07-19 1997-07-16 Thermoforming method using a free flat parison

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR96/09344 1996-07-19
FR9609344A FR2751266B1 (en) 1996-07-19 1996-07-19 THERMO-PLASTIC THERMO-FORMATION PROCESS IN HOT CYCLE USING FREE PARISON

Publications (1)

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WO1998003325A1 true WO1998003325A1 (en) 1998-01-29

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AU (1) AU3773097A (en)
FR (1) FR2751266B1 (en)
WO (1) WO1998003325A1 (en)

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Also Published As

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FR2751266A1 (en) 1998-01-23
FR2751266B1 (en) 1998-10-30
AU3773097A (en) 1998-02-10
EP0920372A1 (en) 1999-06-09

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