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WO2003033238A1 - Repartition peripherique amelioree dans une filiere d'extrusion circulaire - Google Patents

Repartition peripherique amelioree dans une filiere d'extrusion circulaire Download PDF

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Publication number
WO2003033238A1
WO2003033238A1 PCT/EP2002/012192 EP0212192W WO03033238A1 WO 2003033238 A1 WO2003033238 A1 WO 2003033238A1 EP 0212192 W EP0212192 W EP 0212192W WO 03033238 A1 WO03033238 A1 WO 03033238A1
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WO
WIPO (PCT)
Prior art keywords
grooves
die
helical
insert
flow
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.)
Ceased
Application number
PCT/EP2002/012192
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English (en)
Inventor
Ole-Bendt Rasmussen
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Individual
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Individual
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Publication date
Priority claimed from TW090125310A external-priority patent/TW498022B/zh
Application filed by Individual filed Critical Individual
Publication of WO2003033238A1 publication Critical patent/WO2003033238A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/28—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of blown tubular films, e.g. by inflation
    • 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
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • 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
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
    • 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
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/3001—Extrusion nozzles or dies characterised by the material or their manufacturing process
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/325—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles being adjustable, i.e. having adjustable exit sections
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/335—Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular articles
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/335—Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular articles
    • B29C48/336—Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular articles the components merging one by one down streams in the die
    • B29C48/3363—Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular articles the components merging one by one down streams in the die using a layered die, e.g. stacked discs
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/335—Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular articles
    • B29C48/337—Multiple annular extrusion nozzles in coaxial arrangement, e.g. for making multi-layered tubular articles the components merging at a common location
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B29C48/34—Cross-head annular extrusion nozzles, i.e. for simultaneously receiving moulding material and the preform to be coated
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/50—Details of extruders
    • B29C48/695—Flow dividers, e.g. breaker plates
    • B29C48/70—Flow dividers, e.g. breaker plates comprising means for dividing, distributing and recombining melt flows
    • B29C48/705—Flow dividers, e.g. breaker plates comprising means for dividing, distributing and recombining melt flows in the die zone, e.g. to create flow homogeneity
    • 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
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/901—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies
    • B29C48/902—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies internally
    • 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
    • B29L2009/00—Layered products

Definitions

  • the invention concerns a process of forming a tubular film by extruding at least one thermoplastic polymer material A by means of a circular extrusion die which has at least one inlet for A and an exit passageway ending in a circular exit orifice.
  • A passes an arrangement of dieparts having generally planar, conical or cylindrical surfaces supplied with grooves shaped to form channels in a construction which helps to equalize the flow over the circumference of the exit orifice.
  • the invention is an improvement on the commonly used type of equalization in which the flow between the inlet or inlets and the exit is divided into a number of partflows of generally helical form at least through a portion of each channel with space provided for overflow between said portions.
  • the invention is primarily but not entirely related to coextrusion of the thermoplastic polymer material A with one or more further thermoplastic polymer materials .
  • the circumferential distribution by use of helical grooves with space provided for overflow in cylindrical surfaces - originally grooves formed in cylindrical surfaces - was first described about 30 years ago. In this system of distribution the cross-sections of each helical groove and of the space between adjacent grooves which allow overflow, are adapted so that gradually less and less material flows through each groove, and more and more passes over to the neighbour groove, while gradually the depth of the grooves reaches zero.
  • the helical grooves with overflow between neighbours also serve the important purpose to shear-out the "dielines" which otherwise will occur where partflows have met each other. It has been claimed that a single helical groove, extending over several revolutions around the circular die can make a perfect circumferential distribution, provided the design of the groove and intervening spaces for overflow is exactly adapted to the rheological properties of the molten polymer material under the prevailing conditions. However, this is theory, and in practice the polymer flow must first in one or another way be divided into several part flows, each of these proceeding into a helical groove with space provided for overflow between different grooves.
  • the helical die zone is constructed to provide perfect circumferential distribution for one given, commonly used polymer material, and the die with the same helical die zone is applied for another commonly used polymer, it will not be exceptional if the variations in the distribution the will amount e.g. to about +/- 30% (as the inventor has experienced) .
  • GB-A-1384979 (Farrell) which relates to coextrusion, has disclosed that the helical die zone may consist of exchangeable inserts.
  • disassembling and reassembling a die - which also necessarily includes cleaning - is a time consuming and expensive operation.
  • Farrell also discloses that there may be installed an adjustable annular bar after the termination of the spiral grooves and before the polymer material in question joins with another polymer material.
  • this annular bar can set up a higher or lower overall resistance to the flow.
  • the increased resistance at this location in the die will tend to improve the circumferential equalization, it also results in drawbacks, in particular that the increased back-pressure on the extruder leads to a higher consumption of energy and increased temperature in the melt which leaves the extruder.
  • the higher melt temperature has a negative influence on the behaviour of the bubble hauled off from the die.
  • the resistance to the flow should be minimised as much as conveniently possible overall in the die.
  • the coextrusion die for carrying out the process of the invention is similarly characterised. It is noted that the adjustable constraint bar mentioned in GB-A-1384949 (Farrell) , which is installed immediately after the helical die zone, is not adjustable from location to location along its circumference with means for different adjustments at the different locations, and therefore exerts a different action.
  • helix and helical are not restricted to a curve formed on a cylindrical or conical surface which would, if the surface were developed to a flat surface, be a straight line, but include also curves on such surfaces which would not be rectilinear and also plane curves traced by a point which winds about an axis on the plane and which continuously, regularly or somewhat irregularly, recedes from the axis.
  • the condition that the part flows and channels must be of a generally helical form in the helical die zone therefore does not limit the invention to the regular helical form. Although such a regular form usually is very suitable it is not always needed for proper equalization.
  • the "generally helical" portion of each can be relatively short and can be substantially linear and directed at a small angle to the tangent to the circle which meets the inner extent of this short linear portion formed by rotation of that point around the die axis.
  • Another example of an irregular but generally helical form which can be suited for the shaping of the channels is a staggered form in which a first segment of a generally helical partflow follows a channel which is circular around the die axis, then just before this partflow would meet the adjacent partflow the channel bends to project the first mentioned partflow into a second "orbit" further apart from the inlet to the die, as illustrated in fig. 5b.
  • labyrinthine dividing is easiest understood by a reference to figs. 7a, b and e.
  • a main flow branches out to two generally circularly arched equally long and mutually symmetrical first branch-flows, which together occupy essentially 50% of the circumference of the corresponding circle, whereafter each of the first branch-flows branch out to two, in similar way generally circularly arched second branch flows.
  • These in total four second branch flows also occupying together essentially 50% of the circumference of the corresponding circle.
  • the dividing may continue in a similar manner to form 8 or 16 or 32 even 64 part flows.
  • the four second branch- flows may form four of the sides in a regular octagon
  • the eight third branch-flows may form eight of the sides in a regular 16-sided polygon, etc.
  • the labyrinthine dividing has first been described in US-A-2820249 (Colombo) in connection with extrusion coating of cylindrical items.
  • the first description of labyrinthine dividing for extrusion of blown film and in connection with a subsequent equalization by means of helical channels with overflow is found in the above mentioned US-A-4403934 (Rasmussen et al) .
  • At least a part of the channels for the labyrinthine dividing may be formed integrally with the channels for the generally helical flow between the cylindrical planar or conical surfaces of said first dieparts by grooves in at least one surface of a pair of contacting surfaces. This is shown in fig. 7b.
  • the labyrinthine dividing is here extending in a planar pattern, but can also extend in a conical pattern or as in the above mentioned US patent in a cylindrical pattern.
  • a first embodiment of the invention based on the solution that an insert provides an adjustable control of overflow in the helical die zone, is characterised in that the insert is nested in a diepart facing the grooves in another diepart, in such a way that the nesting allows the insert to be moved in the axial direction of the die to adjust the overflow.
  • a series of adjustment devices is provided for the movement. This is illustrated in figs. 3a and 3b.
  • this embodiment can be carried out in such a way that the insert is hinged at its two ends through a flexible generally annular sheet to the said diepart. This is illustrated in figs. 5a and 6.
  • a second embodiment of the invention which also operates with variable overflow in the helical die zone, effects the adjustments by rotational movement of the insert, and is characterised in that the insert is nested in a diepart facing the generally helical grooves in another diepart (hereinafter the first set of grooves) whereby the surface of the insert on the side facing the first set of grooves also is supplied with generally helical grooves (hereinafter the second set of grooves) .
  • the geometrical pattern of the grooves in the first and second sets generally correspond to each other, and the nesting of the insert allows the latter to be rotated around the axis of the die to adjust the position of the helical ridges on the second set of grooves relative to the position of the helical ridges on the first set of grooves, so that said ridges can cover each other to a greater or lesser extent.
  • adjustment devices provided for this rotation. This embodiment is illustrated in fig. 4.
  • a third embodiment of the invention still operating with variable overflow in the helical die zone, is similar to the first embodiment in that the adjustments are effected by axial displacements of the insert .
  • the insert consists of a flexible generally flat annular sheet facing the grooves, which sheet may comprise thicker areas for stabilisation against the pressure in the flow, and which at its inward and outward boundaries is fixed to a stiff diepart.
  • a circular row of adjustment devices is provided on the side of the sheet which is opposite to the grooves. As shown in these sketches it may be carried out in such a way that the spaces for overflow can become independently adjusted at different stages of the flow.
  • an alternative or a supplement to the adjustments of overflow in the helical die zone is the provision of a constraint zone after that zone, with means for different adjustments at different circumferential locations.
  • the constraint zone is provided before the exit orifice and, in the case of coextrusion, before A joins with any other extruded material .
  • a preferred embodiment of the invention following this solution is characterised in that the flow in the constraint zone is generally planar or conical with the genetrix of such cone relatively close to 90° to the axis.
  • the flow is outward or inward in relation to the die axis, and the adjustable constraint is established by means of a flexible generally flat annular sheet facing the grooves, which sheet may comprise thicker areas for stabilization against the pressure in the flow, and which at its inward and outward boundaries is fixed to a stiff diepart.
  • a circular array of adjustment devices is provided on the side of the sheet which is opposite to the grooves.
  • the part-equalization in the helical die zone can with advantage be preceded by part-equalization in a labyrinthine dividing system (as described above) .
  • a labyrinthine system should preferably comprise at least three steps of branching out .
  • this embodiment of the invention could with advantage be carried out with the total helical zone in the die substituted by an efficient labyrinthine distribution. It is usually important to eliminate the dielines, therefore the helical die zone normally is indispensable, however its length can often be reduced to a minimum.
  • a die has labyrinthine distribution of the extrusion flow by at least three steps of branching out to the circularly extending zone before the exit orifice or joining zone, as the case may be, wherein a constraint against the flow is provided which is as defined in the embodiment of the first aspect comprising the constraint zone.
  • Fig. 1 represents prior art relating to annular coextrusion with helical die zones for the circumferential equalization and for elimination of dielines. It shows an axial section through the coextrusion die.
  • the coextrusion is of the sequential type, which probably presently is the most used type of coextrusion when four or more layers are joined.
  • the drawing is derived from WO-A-9800283 (Planeta) .
  • Fig 2 is a bottom view of one of the "mandrels" of the known art die of fig. 1, also derive from W098-A- 00283 (Planeta) .
  • Fig. 3a is a magnification of the die section which in fig. 1 is framed and marked "Dl", however modified so that it represents the first embodiment of the present invention, in which an axially adjustable insert is nested in a diepart to provide control of overflow from groove to groove .
  • Fig.3b is analogous to fig. 3a, but representing a die construction in which the helical die zone is conical .
  • Fig.4 is a magnification of the die section which in fig. 1 is framed and marked "Dl", however modified so that it represents the second embodiment of the present invention, in which an insert which is adjustable by rotation, is nested in a diepart to provide control of overflow from groove to groove.
  • Fig. 5a representing the third embodiment of the invention, is a view similar to that of fig. 4a, but showing the die insert as a flexible generally flat sheet with a number of rigid rings, which are independently adjustable.
  • Fig. 5b represents the section which in fig. 5a is indicated by the line b-b, and shows a modification of the generally helical form of the grooves.
  • Fig.6 shows a modification of fig 3b in which, in order to avoid leakage or stagnation, the insert is hinged at its two ends through flexible annular sheets to a major diepart.
  • Fig. 7a illustrates a preferred coextrusion die construction, of general principles different from the prior art die of fig. 1, and for each extruded component supplied with a variable constraint immediately after the helical die zone. This constraint is made variable with means for different adjustments at different circumferential locations.
  • Fig.7b represents the section which in fig. 7a is indicated by c-c and shows the pattern of grooves starting as a labyrinthine system and continuing in a helical system.
  • Fig. 7c is a magnification of the die section which in fig. 7a is framed and marked "D2", and illustrates in detail the variable constraint.
  • Fig. 7d is an unfolding of the circular section formed by rotation of the line d-d in fig. 7c.
  • fig. 7a is an unfolding of the circular section formed by rotating each of the lines e-e in fig. 7a around the die axis. It shows the first two steps of the labyrinthine dividing.
  • Fig.7f is a magnification of the die section which in fig. 7a is framed and marked D3 , and illustrates in detail the joining of the three coextruded components.
  • the prior art die shown in figs. 1 and 2 has axis (1) and consists of clamped together discs and "shell" - or "bowl" formed parts.
  • This construction of an extrusion die has the advantage that it allows coextrusion of many components, but has the drawback that these components must have relatively similar rheologies, otherwise the thickness of the individual layers may become uneven.
  • the present invention can with advantage be applied in each of these cases.
  • the annular insert (101) here seen in an axial section, is nested in the diepart (2a) opposite the grooves in the diepart (3a) .
  • the nesting allows axial movement of this insert.
  • the polymer flow urges the insert away from the grooves, but the insert is held in position by the spirally curved tap (102) .
  • the tap is a rotatable element having an outer spiral cam surface, which bears against the insert and which can be rotated through its shaft (103) . Due to its spiral curving, the axial position of the insert (101) , which controls the amount of overflow, can hereby be adjusted.
  • curved taps (102) there is a plurality of such curved taps (102) around the circumference, the number depending on the stiffness of the insert, and their adjustment through shafts (103) is preferably coordinated by transmission means. These means and the means for fixing the position is not shown.
  • a clearance e.g. 0.1mm, which is sufficient to allow a very small drain of polymer from the main flow between (2a) and (3a) into the space (104) under the insert, and therefrom out through the drain channel (105) .
  • Fig. 3b shows how the first embodiment of the invention is carried out when the construction of the diepart is conical. Except for the conical shapes the constructions are similar to those in fig. 3a.
  • Fig. 4 is generally similar to fig. 3a except that the adjustments of the overflow takes place by rotational instead of axial displacements of the insert (101) .
  • the insert is nested rotatably in diepart (2a) .
  • the insert is supplied with grooves (106) and the pattern of the latter exactly match with that of the grooves in diepart (3a) .
  • the drawing shows the insert in a position in which there is maximum overflow.
  • the spiral pattern is a pattern of regular spirals (not e.g. a spiral-like arrangement as that shown in fig. 5b) so the spacing which provides for the overflow can be continuously varied by turning the insert (101) . This is here done by means of a gear-wheel (107) .
  • the gear-wheel fits into a gearing at the bottom of the insert and is turnable through the shaft (103) .
  • one gear-wheel is enough, but in practice there should normally be at least two, e.g. arranged diametrically opposite each other. Means for coordination of these gear-wheels are not shown.
  • the surface of the insert (101) and the surface into which it fits are conical to provide sealing, but for reasons of safety there is still arranged a drain (105) .
  • Such rotational adjustment can of course be modified for a conical and even for cylindrical construction of the dieparts (as that in fig. 2b) . In fig.
  • the insert which controls overflow in a part of the helical die zone is adapted to allow independently adjustable amounts of overflow at different distances from the die axis.
  • the beginning of the grooves - see fig. 5b - have the staggered form already mentioned, in which a first segment of a generally helical partflow in "orbit 1" marked (I) follows a channel Which is circular around the die axis, then just before this partflow would meet the adjacent partflow the channel bends to project the first mentioned partflow into "orbit 2" marked (II) .
  • each annular thickening (110) is adjusted by means of spirally curved taps, of which of one (102) for the innermost annular thickening is shown. It is turnable through the shaft (103). Similar spirally curved taps for the other annular thickenings are not shown but would appear in other axial sections of the die. For each of the annular thickenings (110) there are several such taps (102) and they are mutually coordinated by mechanical means (not shown) . The required number of such taps depends on the stiffness of the thickenings and the expected pressure in the flow.
  • a practical technical equivalent to such coordinated, spirally curved taps is a ring which is turnable around the die axis like the ring (101) in fig. 4, and which is supplied with a number of wedges which press against corresponding wedges at the bottom side of a ring (101) for adjustment of this ring's axial position.
  • this construction there should be one such adjustment device for each ring (110) .
  • the drain (105) is not strictly needed in this construction provided parts (111) and (112) fit tightly with diepart (2a) , but is preferable as a safety precaution.
  • the outer boundary (112) of the insert is screwed to diepart (2a) by means of bolts (113) .
  • the adjustment by means of spirally curved taps (102) with shafts (103) is similar to the adjustment means in fig. 3b.
  • the flow In order to allow axial movement of the insert (101) by such hinging, the flow must be generally planar at the inlet to and at the exit from this part of the helical die zone, as shown.
  • the construction shown in fig. 6 can be modified for use of generally flat annular shapes instead of conical shapes of the insert and the immediately adjacent regions of parts (2a) and (3a) .
  • it can also be modified for generally cylindrical shape of the insert and the immediately adjacent region of part (2a) and (3a) .
  • the insert must also be supplied with helical grooves on the side which faces the flow, and these grooves must correspond to the grooves in the fixed diepart - like in fig- 4, but now in a cylindrical instead of a planar arrangement.
  • the insert is adjusted to an axial position in which the ridges on one set of grooves directly faces the ridges on the other set of grooves, the overflow will be at minimum, and if the axial position of the insert is continuously moved away from this position, the overflow will continuously increase.
  • the means to make exact adjustments of the evenness of each flow over the circumference consists of a constraint device after the helical zone and before the location of flow-joining.
  • the major part of the coextrusion die which has axis (1) , is made from two shell or bowl formed parts (5) and (6) and two disc- formed parts (7a) and (7b) , which parts are clamped together. These parts form the ends of a labyrinthine dividing system for each of three polymer materials A, B and C, and form helical grooves with overflow, as well as a common exit passageway and an exit orifice, which here is shown at the periphery.
  • the die also comprises three smaller disc-formed parts (32) , (33) and (34) , which together form the beginning of the labyrinthine dividing channel system.
  • each of the molten polymer materials A, B and C divide out into the two channel branches (35a) and (35b) , see fig. 7e.
  • the branches are formed by grooves in both parts (32) and (33) , but it could be a groove in one part only. From each end of these branches each component passes through a hole in the disc (33) , and at the other surface of (33) each of the two part-flows divide out into two part-flows (36a) and (36b) , in total four branches, so that each component A, B and C now has become four part- flows.
  • each component passed through a hole (37) in disc (34) which leads into the dieparts (5) , (7a) or (7b) .
  • Each hole (37) continues as a bore (38) through shell-part (5) , see fig. 7a.
  • the bores (38) directly form the four inlets to the system of grooves between (5) and (7a) .
  • the bores (38) are continued as bores (39) through disc (7a) .
  • the bores (39) directly form the four inlets to the system of grooves between discs (7a) and (7b) .
  • the bores (39) are continued as bores (40) through disc (7b) , and these bores directly form the four inlets to the system of grooves between disc (7b) and bowl (6) . Since the three sections marked c-c are considered identical except for the inlets, fig. 7b does in fact show the continued system of flow of each component B, A and C.
  • the dieparts (5) , (7a) , (7b) and (6) are clamped together by bolts (not shown) .
  • each of the four partflows divide out into two, so that each component forms a total of eight partflows (13), and each of these eight partflows proceeds through one of the helical grooves (14) with overflow in the spaces (15) .
  • not only the four but all eight partflows of each component may be formed by labyrinthine dividing upstream of the dieparts (5) , (7a) and ( €) , or it may be advantageous, especially for dies of a large exit orifice diameter, to divide to more than eight partflows, e.g. to 16 or 32 partflows. There is not shown any devices for control of the amount of overflow.
  • the serrated, but generally circular, broken curve (16) in fig. 7b shows where the overflow begins.
  • the downstream limit of the helical die zone is in fig. 7b indicated by the broken circle (16b) . This limit is also shown in fig. 7c.
  • the broken lines (17) in fig. 7a indicate that the channels which are seen almost in cross-sections are connected outside the section which is represented in these drawings .
  • Figs . 7c and d show the constraint device between the helical die zone and the zone where the polymers join.
  • This device has a flexible annular part (115) , and upstream and downstream of this it is stiff in zones (116) and (117) .
  • the flexible part (115) can be considered an annular membrane, however it has a semi- flexible annular zone (115a) in its middle, as shall be explained below.
  • the stiff part (117) on the downstream side is fixed to the adjacent die disc (7c) by a circular row of bolts of which one (43) is shown.
  • the pressure in component A pushes the membrane part of the constraint device towards a circular row of spirally curved taps (44) each on a turnable shaft (45) which is nested in a bore in the die disc (7b) .
  • a turnable shaft (45) which is nested in a bore in the die disc (7b) .
  • the distance from axis to axis of these taps can in practice be down to about 15-20mm.
  • the stiffness of the semi-flexible annular zone (115a) must be adapted to the distance between the taps to give an appropriate variation of the constraint over the circumference.
  • the means for turning the many shafts (45) and fixing their positions, e.g. by the use of spindles and spindle wheels, are not shown. If the taps are very close to each other, the shafts should point towards different axial levels in the hollow space in the middle of the die, where these devices are arranged.
  • the material is hardened steel, and the length of the "hinges" can conveniently be about 10 mm.
  • the molten tubular B/A/C film is turned over the cooled ring (22) and is hauled off, blown and aircooled by conventional means (not shown) .
  • the ring (22) is directly fixed to the shell-part (6) of the die through a heat insulating material (23) .
  • the ring (22) is hollow, and the cooling takes place by circulation of water or oil, which may be temperature-controlled.
  • This cooling medium is pumped into and out of the ring (22) through pipes, of which one (24) for the inlet is shown. These pipes are preferably passed through the die cavity in the region around the axis of the die .
  • One of the circular lips (25) of the orifice (21) is preferably made flexible as indicated and is made adjustable by means of row of screws close to each other of which one (26) is shown. Such adjustment is well known from the construction of ordinary flat dies, and in fact the die of fig. 7a can be considered a flat die, although the exit orifice (21) is not straight but circular. Screw (26) is shown pressing on a lip of the die (25) . Although the screw could also be a push-pull screw, the pressure in the melt may give a sufficient opening force for it only to push the lip.
  • This peripherical extrusion by which the exit orifice is made adjustable like in flat extrusion dies, adds very efficient adjustment means for the gauge of the final multilayer film to the means for adjusting the individual layers.
  • the exit channel (18) can alternatively be bent towards the axial direction so that the exit (21) can be located at the end of the die as it is normal in extrusion of tubular film.
  • a relatively large continuous hollow space extending from the die axis (1) to the innermost cylindrical surfaces of the clamped-together dieparts (which surfaces may e.g'. be conical instead of cylindrical) . This space can be very useful e.g.
  • a graph showing the throughput of each component of coextrusion in dependence of the circumferential position will normally show a number of relative maxima and relative minima, which for one tour around the circumference each will equal the number of spirals. If the die is evenly constructed and evenly heated/cooled, and if the components are fed into the die with a homogenous temperature, the curve segments between two adjacent maxima will all be very similar. In that case the construction of the constraint device after the helical grooves can be simplified. Thus, if the distance between two neighbour grooves is about 5 cm or less, measured along the circle at the end of the grooves, it may be sufficient to have adjustments screws or the like (e.g.
  • All screws for the maxima may be supplied with gearing and be synchronised by means of a gear-ring, which has its axis coinciding with the die axis (1) and all screws for the minima may be similarly synchronised under use of another, similar gear-ring.
  • the adjustment of these two gear-rings is similar to what is explained in connection with fig. 4.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

L'invention concerne une amélioration apportée à un procédé et à un dispositif, permettant d'obtenir une répartition périphérique globalement égale dans une filière d'extrusion annulaire par division de l'écoulement entre l'entrée (1a, 10) et un orifice de sortie circulaire (21) en plusieurs écoulements traversant des canaux (4, 14) comprenant au moins une partie de forme globalement hélicoïdale, ces canaux hélicoïdaux étant séparés par un espace (15) de débordement. Pour appliquer ces améliorations, il suffit soit a) de contrôler le débordement à l'aide d'un insert réglable (101) permettant d'obtenir un espacement variable (15) pour le débordement, entre les canaux hélicoïdaux (4, 14), soit b) d'exercer une force de contrainte (115, 116, 117) opposée à l'écoulement, dans une zone qui s'étend de façon circulaire, en aval de la partie hélicoïdale des canaux, mais en amont de l'orifice de sortie et, en cas de coextrusion, avant l'assemblage des composants (19, 20). Cette force de contrainte est réglable à l'aide d'un moyen de réglage (44, 45), d'un point à un autre, le long de sa circonférence.
PCT/EP2002/012192 2001-10-12 2002-10-14 Repartition peripherique amelioree dans une filiere d'extrusion circulaire Ceased WO2003033238A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
TW90125310 2001-10-12
TW090125310A TW498022B (en) 2000-12-22 2001-10-12 Methods and apparatus for extruding a tubular film under use of planely or conically extending helical grooves for the circumferential equalization
PCT/EP2001/012430 WO2002051617A1 (fr) 2000-12-22 2001-10-15 Procédés et appareil d'extrusion d'un film tubulaire
EPPCT/EP01/12430 2001-10-15
GB0214424.4 2002-06-21
GBGB0214424.4A GB0214424D0 (en) 2002-06-21 2002-06-21 Method and apparatus for improved circumferential distribution in an annular extrusion die

Publications (1)

Publication Number Publication Date
WO2003033238A1 true WO2003033238A1 (fr) 2003-04-24

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PCT/EP2002/012192 Ceased WO2003033238A1 (fr) 2001-10-12 2002-10-14 Repartition peripherique amelioree dans une filiere d'extrusion circulaire

Country Status (3)

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GB (1) GB0214424D0 (fr)
TW (1) TW548175B (fr)
WO (1) WO2003033238A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1579976A1 (fr) * 2004-03-23 2005-09-28 Kiefel Extrusion GmbH Tête de soufflage avec distribution de matière fondue
DE102007050694A1 (de) * 2007-10-22 2009-04-23 Ulrich BÜTTEL Blaskopf für eine Blasfolienextrusionsanlage
WO2013149176A1 (fr) 2012-03-29 2013-10-03 Gloucester Engineering Co., Inc. Configuration de rainure en spirale de filière annulaire
DE102010042882B4 (de) * 2010-10-25 2014-01-16 Windmöller & Hölscher Kg Folienblaskopf
US9114578B2 (en) 2010-12-08 2015-08-25 Windmoeller & Hoelscher Kg Film blowing head

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1964675A1 (de) * 1969-12-23 1971-07-01 Windmoeller & Hoelscher Folienblaskopf zur Herstellung von Kunststoff-Schlauchfolien
GB1384979A (en) * 1973-04-05 1975-02-26 Farrell J J Extrusion die for blowing plastic film
DE3820907A1 (de) * 1988-06-21 1989-12-28 Battenfeld Extrusionstech Extrusionskopf zum strangpressen von schlauch- oder rohrfoermigen vorformlingen
US6099290A (en) * 1995-09-27 2000-08-08 Gross; Heinz Apparatus for variable limitation of a flat flow channel
EP1112834A1 (fr) * 1999-12-30 2001-07-04 EXTRUSION DIES, Inc. Ensemble à membrane pour filière d'extrusion

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1964675A1 (de) * 1969-12-23 1971-07-01 Windmoeller & Hoelscher Folienblaskopf zur Herstellung von Kunststoff-Schlauchfolien
GB1384979A (en) * 1973-04-05 1975-02-26 Farrell J J Extrusion die for blowing plastic film
DE3820907A1 (de) * 1988-06-21 1989-12-28 Battenfeld Extrusionstech Extrusionskopf zum strangpressen von schlauch- oder rohrfoermigen vorformlingen
US6099290A (en) * 1995-09-27 2000-08-08 Gross; Heinz Apparatus for variable limitation of a flat flow channel
EP1112834A1 (fr) * 1999-12-30 2001-07-04 EXTRUSION DIES, Inc. Ensemble à membrane pour filière d'extrusion

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1579976A1 (fr) * 2004-03-23 2005-09-28 Kiefel Extrusion GmbH Tête de soufflage avec distribution de matière fondue
DE102007050694A1 (de) * 2007-10-22 2009-04-23 Ulrich BÜTTEL Blaskopf für eine Blasfolienextrusionsanlage
DE102007050694B4 (de) * 2007-10-22 2012-05-10 Ulrich Büttel Blaskopf für eine Blasfolienextrusionsanlage
DE102010042882B4 (de) * 2010-10-25 2014-01-16 Windmöller & Hölscher Kg Folienblaskopf
US9114578B2 (en) 2010-12-08 2015-08-25 Windmoeller & Hoelscher Kg Film blowing head
WO2013149176A1 (fr) 2012-03-29 2013-10-03 Gloucester Engineering Co., Inc. Configuration de rainure en spirale de filière annulaire
EP2830853A4 (fr) * 2012-03-29 2015-11-25 Gloucester Eng Co Inc Configuration de rainure en spirale de filière annulaire

Also Published As

Publication number Publication date
GB0214424D0 (en) 2002-07-31
TW548175B (en) 2003-08-21

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