EP1343625A2 - Dispositif d'extrusion - Google Patents

Dispositif d'extrusion

Info

Publication number
EP1343625A2
EP1343625A2 EP01986911A EP01986911A EP1343625A2 EP 1343625 A2 EP1343625 A2 EP 1343625A2 EP 01986911 A EP01986911 A EP 01986911A EP 01986911 A EP01986911 A EP 01986911A EP 1343625 A2 EP1343625 A2 EP 1343625A2
Authority
EP
European Patent Office
Prior art keywords
screw
zone
extrusion device
thread
outlet opening
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.)
Withdrawn
Application number
EP01986911A
Other languages
German (de)
English (en)
Inventor
Franck PÖHLER
Peter Stommel
Wilfried Schwarz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Reifenhaeuser GmbH and Co KG Maschinenenfabrik
Original Assignee
Reifenhaeuser GmbH and Co KG Maschinenenfabrik
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 Reifenhaeuser GmbH and Co KG Maschinenenfabrik filed Critical Reifenhaeuser GmbH and Co KG Maschinenenfabrik
Publication of EP1343625A2 publication Critical patent/EP1343625A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
    • B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
    • B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
    • B29B7/40—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft
    • B29B7/42—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft with screw or helix
    • B29B7/425—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with single shaft with screw or helix with screw surrounded by a casing provided with grooves or cavities
    • 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
    • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
    • 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
    • B29C48/505—Screws
    • B29C48/56—Screws having grooves or cavities other than the thread or the channel
    • 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
    • B29C48/68—Barrels or cylinders
    • B29C48/685—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads
    • B29C48/686—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads having grooves or cavities
    • 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

Definitions

  • the invention relates to an extrusion device for the extrusion of thermoplastic materials, comprising a screw cylinder with an inlet and outlet opening and a screw which is arranged in the screw cylinder and can be driven in rotation and has an external screw thread.
  • extrusion devices which are generally also referred to as single-screw extruders, are widely known, for which reference is made to DE 35 04 773 A1 by way of example only.
  • the screw cylinder and the screw are each correspondingly divided into different zones, starting from the entry opening initially forming a feed zone communicating with the screw cylinder and the screw, in which the screw is optionally available with a constant or variable flight depth External screw thread and the screw barrel are formed with a smooth or grooved inner wall.
  • the thermoplastic to be processed is offered through the inlet opening and the feed zone of the screw cylinder to the feed zone of the screw and the material taken up in the screw feed zone is made possible by high friction between plastic and screw barrel and the smallest possible friction between plastic and screw axially transported in a conveying direction pointing from the inlet opening towards the outlet opening.
  • the screw cylinder and the screw then have a plasticizing zone in which the plastic material introduced in the feed zone is melted into its plastic state and then transported in the direction of the outlet opening via an ejection zone and from there to one Downstream extruder tool is fed.
  • Thermoplastic plastics as granules or powders, have a bulk density that is 40 to 50% lower than the solid, processed state.
  • the feed zone conveys the material with increased passage volume against the resistance of the following zones and displaces the air between the granules or powder grains.
  • the melting process can already begin in the feed zone and is completed in the plasticizing zone or is effected exclusively in the plasticizing zone of the extrusion device. The majority of the energy required for plasticization is supplied by shearing the melt, i. H. through sales of drive energy.
  • the invention has therefore set itself the task of showing an extruder of shortened design, which at the same time has a throughput and a performance that is comparable with the previously known extrusion devices of the aforementioned conventional design or even exceeds them.
  • This object is achieved according to the invention by forming an extrusion device according to the features of claim 1.
  • the invention proposes an extrusion device with a conventional feed zone, which is followed by a plasticizing zone, which has the following features:
  • the screw cylinder is formed with an internal thread which is introduced into the inner wall and runs counter to the external screw thread
  • the thread depth of the internal thread correspondingly decreases in the direction of the outlet opening.
  • the feed zone has a screw with a constant or variable thread depth of the external screw thread and a screw cylinder with a smooth or grooved inner wall, which ensures a high conveying capacity of the granular or powdered plastic is responsible from the inlet opening into the extrusion device.
  • the plasticization of the plastic material can begin in this feed zone.
  • a plasticizing zone is then added to the feed zone, in which a high shear stress on the plastic material conveyed through the feed zone is achieved on the one hand by the external screw threads running counter to one another and on the other hand by the internal thread introduced into the inner wall of the screw cylinder.
  • the increase in the flight depth of the screw or the corresponding decrease in the flight depth of the internal thread of the screw cylinder causes a thorough mixing of the plastic material being conveyed.
  • the above-described increase or decrease in the flight depths of the worm or worm cylinder can, for example, take place continuously.
  • This shear stress within the plasticizing zone of the plasticizing device according to the invention is so strong that the total length of the extrusion device required to completely melt the conveyed thermoplastic material and homogenize the melt can be considerably shortened compared to an extrusion device of conventional design.
  • the feed zone can have a length of 1 to 15 D, based on the diameter D of the screw, and the length of the shear sections can be only about 1 to 5 D.
  • thermoplastic plastic melt is also thoroughly mixed, further screws and screw cylinder zones arranged entirely downstream of the plasticizing zone can optionally be dispensed with and the outlet opening from the extrusion device according to the invention can already be omitted be arranged immediately behind the plasticizing zone, which ensures a very short design of the extrusion device.
  • the extrusion device of the plasticizing zone in the direction of the outlet opening subsequently also comprises an ejection zone in which the screw cylinder has a smooth inner wall in a manner known per se and this ejection zone has a length of up to 15 D.
  • the molten plastic mass is homogenized and processed in this ejection zone, possibly with pressure increase, in order to then feed it to a downstream tool.
  • the screw in the discharge zone can be designed with a shear and / or mixing part or without such parts.
  • the flight depth of the screw is varied between 10 to 90% of the total flight depth within the shear section.
  • the total flight depth formed from the sum of the flight depth of the external screw thread and the internal screw cylinder thread remains constant over the entire shear section or is varied.
  • the external screw thread and the internal thread in the area of the shear section can advantageously be designed with multiple threads with different numbers of threads, which likewise increases the shearing and mixing action of the shear section.
  • a variation in the number of gears and the pitch of the screw and cylinder threads can also be provided in the shear section, in particular different gears and / or pitches can be provided when viewed over the length of the shear section.
  • the feed zone can also be equipped, if necessary, with different pitch inclinations in order to act here to increase performance and to ensure good throughput through the shear section within the plasticizing zone of the extrusion device according to the invention.
  • the extrusion device according to the invention as a so called high-velocity type, so that the screw at speeds of up to 1000 min "1 is rotatably driven in the worm cylinder.
  • a high shearing energy is on the one hand provided, but on the other hand, in a compact design and an extremely powerful extrusion means for Provided.
  • a preferred design of the extrusion device according to the invention which can be adapted to different production tasks, furthermore provides that the screw cylinder and the screw are subdivided into module sections which form the feed zone, the plasticizing zone with shear section and optionally the ejection zone, and can be joined together from these.
  • FIG. 1 shows a partial enlargement of the shear section of the plasticizing zone of an extrusion device according to the invention
  • Figure 2 is an illustration of a conventional extrusion device according to the prior art.
  • FIG. 2 A conventional or conventional design of a single-screw extruder according to the prior art is shown schematically in FIG. 2. It comprises a screw cylinder 1, which is only indicated and within which a screw 2 with an external screw thread 20 is mounted so as to be rotatable about its own axis by means of a drive (not shown in more detail).
  • the screw cylinder 1 has an inlet opening 11 at one end and an outlet opening 12 at its other end.
  • Both the screw cylinder 1 and the screw 2 are functionally divided into different zones, which are designated E, P and A in FIG. 2.
  • E denotes the feed zone
  • P the adjoining plasticizing zone
  • A the ejection zone A adjoining it in each case both of screw 2 and screw cylinder 1.
  • thermoplastic to be extruded is filled into the extrusion device via the inlet opening 11 in granular or powder form and enters the feed area E of screw 2 and screw cylinder 1.
  • the granular or powdered plastic is conveyed as a result of the rotation of the screw 2 in a conveying direction F in the direction of the outlet opening 12 and is thereby continuously compacted, so that this originally granular or powdered plastic is gradually plasticized and sheared by shear and friction and by external heat supply is melted.
  • the gradually plasticized plastic is fed out of the feed zone E to the plasticizing zone P, in which the core 21 of the screw 2 has a gradually increasing diameter, so that the remaining one
  • the depth of flight between the screw core 21 and the inner wall 10 of the screw cylinder 1 is reduced and the thermoplastic is completely plasticized and melted by further increasing the pressure and the shear energy.
  • thermoplastic mass reaches the discharge zone A, in which it is homogenized, processed and, if necessary, fed to the discharge opening 12, from where it is fed to a downstream tool, not shown here.
  • the screw cylinder 1 has a smooth inner wall 10.
  • An exception to this can only exist in the area of the feed zone E if it is an extrusion device with a so-called grooved feed zone, in which the inner wall 10 of the screw cylinder 1 is formed in the area of the feed zone E with grooves pointing in the conveying direction F, which increase the Conveying capacity caused by the formation of solid wedges in the plastic material.
  • An extrusion device designed in this way usually has a screw diameter D between 25 and 250 mm with a total screw length over all zones of approximately 20 to 33 D.
  • FIG. 1 An extrusion device according to the invention is shown in detail in FIG. 1.
  • this has a feed zone E which is constructed almost identically in the manner explained above and differs from one another therefore does not differ from the state of the art or makes only an insignificant difference and need not be shown or explained again here.
  • Deviations from that of the prior art extrusion device according to FIG. 2 arise within the plasticizing zone P, which is shown in FIG. 1 as a detail of the entire extrusion device and directly adjoins the feed zone E according to FIG. 2.
  • the plasticizing zone P comprises a shear section S of the screw cylinder 1 and the screw 2, in which, viewed in the conveying direction F in the direction of the discharge opening 1 2, the screw 2 has a continuously increasing flight depth G2. This is achieved in that the individual webs forming the external screw thread 20, viewed in the direction of conveyance F, continuously increase in diameter and protrude beyond the constant cylindrical screw core 21 to an ever increasing extent.
  • the screw cylinder 1 is not provided with a smooth inner wall, as is the case in the prior art, but instead has an internal thread 1 introduced into the inner wall 10 00, whose flight depth G1, viewed in the conveying direction F, is designed to decrease corresponding to the increase in the flight depth G2 of the screw 2.
  • the individual thread webs 101 which define the internal thread, viewed in the conveying direction F are designed with a continuously decreasing flank height which defines the thread depth G1.
  • the flight depth G2 of the screw 2 is varied from 10 to 90% of the total flight depth G1 + G2, ie the sum of the individual flight depths G1 and G2.
  • both threads 20 are designed in opposite directions.
  • the worm thread 20 is designed to be right-handed
  • the internal thread 100 of the worm cylinder 1 is designed to be left-handed, although the exactly opposite variant is of course also possible.
  • the total aisle depth, i.e. H. the sum of the individual aisle depths G1 + G2 can be made constant or can be increased or decreased in the conveying direction F. In this way it is both possible to keep the shear gap SP between the webs of the external screw thread 20 and the thread webs 101 constant over the length of the shear section S or to vary this shear gap SP.
  • the desired high throughput is simultaneously ensured by the feed zone E upstream of the plasticizing zone P, the large one Conveyed quantities of raw material under pressure increase and pressed into the plasticizing zone. A partial plasticization of the plastic can already take place here.
  • the entire plasticizing zone P can either consist exclusively of a shear section S or can be supplemented by small further screw flights within a cylinder with a smooth inner wall either before or after the shear section S. If necessary, an ejection zone A still following the plasticizing zone P can be dispensed with entirely, and the outlet opening 12 can directly adjoin the plasticizing zone P.
  • an ejection zone A can also be provided downstream of the plasticizing zone P in the direction of the outlet opening 12, in which the screw cylinder has a smooth inner wall and the screw is designed with a constant or variable flight depth with and without a shear and / or mixing part can be to homogenize the melt even further.
  • the extrusion device according to the invention is equally suitable for processing a wide variety of thermoplastics, in particular for processing polyolefins, such as polyethylene and polypropylene and for processing polyamide and polyester (PET, PBT), to which additives, fillers and the like are known in a manner known per se can be added.
  • polyolefins such as polyethylene and polypropylene
  • PET, PBT polyamide and polyester
  • the processed plastics can either be extruded in a compact form or, if necessary, a blowing agent can also be added to them in order to cause the thermoplastic to foam up after it has left the outlet opening 12.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

L'invention concerne un dispositif d'extrusion pour extruder des matières thermoplastiques, qui contient un cylindre à vis sans fin avec une ouverture d'entrée et une ouverture de sortie et une vis sans fin pouvant être entraînée en rotation montée dans le cylindre à vis sans fin et présentant un filet extérieur. Le cylindre à vis sans fin et la vis sans fin présentent dans chaque cas de manière correspondante, une zone d'alimentation communiquant avec l'ouverture d'entrée et dans laquelle sont formés la vis sans fin à profondeur de spire de vis constante ou variable du filet extérieur de la vis sans fin et le cylindre à vis sans fin avec une paroi intérieure lisse ou rainurée, l'une et l'autre présentant sur la zone d'alimentation en direction de l'ouverture de sortie, une zone de plastification comprenant elle-même une section de cisaillement dans laquelle le cylindre de vis sans fin se présente sous forme de filet intérieur s'étendant en sens contraire du filet extérieur de vis sans fin. La profondeur de spire de la vis sans fin augmente en direction de l'ouverture de sortie et la profondeur de spire du filet intérieur du cylindre de vis sans fin diminue en conséquence en direction de l'ouverture de sortie.
EP01986911A 2000-12-22 2001-12-20 Dispositif d'extrusion Withdrawn EP1343625A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE20021817U 2000-12-22
DE20021817U DE20021817U1 (de) 2000-12-22 2000-12-22 Extrusionseinrichtung
PCT/EP2001/015094 WO2002051618A2 (fr) 2000-12-22 2001-12-20 Dispositif d'extrusion

Publications (1)

Publication Number Publication Date
EP1343625A2 true EP1343625A2 (fr) 2003-09-17

Family

ID=7950505

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01986911A Withdrawn EP1343625A2 (fr) 2000-12-22 2001-12-20 Dispositif d'extrusion

Country Status (3)

Country Link
EP (1) EP1343625A2 (fr)
DE (1) DE20021817U1 (fr)
WO (1) WO2002051618A2 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10354172A1 (de) * 2003-11-19 2005-06-23 Entex Rust & Mitschke Gmbh Extruder

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1294700A (fr) * 1961-07-12 1962-05-26 Roehm & Haas Gmbh Presse à vis sans fin à grande puissance
US4462692A (en) * 1982-11-27 1984-07-31 Frenkel C-D Aktiengesellschaft Screw extruders
DE4039942C1 (fr) * 1990-12-14 1992-01-30 Berstorff Gmbh Masch Hermann
DE19938499A1 (de) * 1999-08-13 2001-02-15 Krauss Maffei Kunststofftech Plastifiziereinheit und Verfahren zum Plastifizieren von thermisch erweichbaren Materialien

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO02051618A2 *

Also Published As

Publication number Publication date
DE20021817U1 (de) 2002-05-02
WO2002051618A2 (fr) 2002-07-04
WO2002051618A3 (fr) 2002-10-24

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