Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
  • F26B13/24—Arrangements of devices using drying processes not involving heating
  • F26B13/28—Arrangements of devices using drying processes not involving heating for applying pressure; for brushing; for wiping
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B13/00—Machines and apparatus for drying fabrics, fibres, yarns, or other materials in long lengths, with progressive movement
  • F26B13/10—Arrangements for feeding, heating or supporting materials; Controlling movement, tension or position of materials
  • F26B13/12—Controlling movement, tension or position of material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
  • F26B21/004—Nozzle assemblies; Air knives; Air distributors; Blow boxes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
  • F26B5/02—Drying solid materials or objects by processes not involving the application of heat by using ultrasonic vibrations

Definitions

• the invention relates to a device for drying plastic sheets, comprising at least one group of nozzles, each group having at least two nozzles, between which a gap is provided for the passage of a plastic sheet.
• the invention further relates to a method for drying plastic sheets.
• An industrial process for the production of films is to extrude plastic through a slot die into a water bath, where the plastic cools and thereby solidifies into a plastic sheet.
• the plastic film produced in this way is pulled out of the water bath by a suitable removal device in order to be fed to further processing steps, such as cutting and stretching.
• a suitable removal device in order to be fed to further processing steps, such as cutting and stretching.
• suction nozzles are arranged downstream of the draw-off device on both main sides of the film web, which suck water adhering to the film during the transport of the film between the suction nozzles.
• this drying process requires a relatively long residence time of the film in the suction section, or in other words, only allows the film to be transported at a low speed between the suction nozzles in order to ensure that the film is completely dry. Therefore, the drying process in the industrial production of plastic films or products made from them, such as stretched plastic tapes, with regard to the achievable production speed, represent a "bottleneck" which can only be alleviated by correspondingly multiplying the suction nozzles and, associated therewith, multiplying the performance of the devices for generating the necessary vacuum. However, this requires an expensive and impractical enlargement of the entire system.
• the invention has for its object to eliminate or at least reduce the above problems in the drying of plastic films.
• This object is achieved by a novel device and a method for drying plastic sheets, the device for drying plastic sheets comprising at least one group of nozzles, each group having at least two nozzles, between which a gap is provided for the passage of a plastic sheet.
• the air streams from each of the nozzles in a group can now be directed onto the gap between them in such a way that a plastic web which is passed through the gap is set into vibration. This vibration of the plastic web causes water drops on the web to be thrown off the web in a very short time.
• the device according to the invention enables extremely rapid drying of the plastic web and thus a significantly improved transport speed of the plastic web through the drying device compared to the prior art.
• a preferred embodiment of the device according to the invention is thereby characterized in that the nozzles comprise nozzle tubes with a plurality of air outlets.
• This embodiment is robust and reliable, and the nozzle tubes can be arranged in many different configurations.
• a control device for controlling the air supply to the nozzles is advantageously provided, so that the nozzles can be controlled individually, in groups or together, different nozzles being able to be supplied with air in succession or different predetermined air velocity profiles being able to be generated.
• a tensile stress sensor is provided for determining the tensile stress exerted on the plastic web.
• the signals from the tension sensor can be fed to the control mentioned as input parameters and influence the automatic selection of a specific control program.
• the water thrown off the plastic sheet is appropriately collected by drain plates, which at least partially surround the nozzles.
• Suction devices are advantageously provided on or under the drain plates, which serve to discharge the water collected from the drying device.
• the vibrating plastic web acts acoustically like a plate vibrator and generates a correspondingly high noise level
• the nozzles are arranged in a sound-absorbing housing.
• the vibration of the plastic web depends on the web tension.
• a device preferably adjustable during operation, for adjusting the tension of the plastic web in the area of the nozzles.
• the invention also relates to a method for drying plastic sheets
• the air supply to the nozzles is advantageously controlled individually, jointly or in groups, preferably by alternately switching compressed air on and off, or by following predetermined air velocity profiles.
• the control of the nozzles can take place as a function of the values of a sensor measuring the plastic web tensile stress.
• FIG. 1 schematically shows a preferred embodiment of the invention in a side view
• FIG. 1A shows a part of the embodiment of FIG. 1 schematically in a front view
• FIG. 2 and FIG. 5 show various further arrangements of the nozzles schematically in a front view.
• Fig. 1 represents a preferred embodiment of the device for drying plastic webs according to the invention
• a first pair of take-off rollers 1, 1 which is a 0 plastic web 3 wetted with water drops 19, which by known per se - not in the drawing - Extruding plastic from a slot die into a water bath, in which the plastic solidifies into the film web, is produced, is pulled out of the water bath.
• a second pair of draw rollers 2, 2 Downstream of the first pair of draw rollers 1, 1 there is a second pair of draw rollers 2, 2, which, on the one hand, are designed for a predetermined voltage
• plastic web 3 between the two pairs of take-off rolls 1, 1; 2.2 ensures and on the other hand the plastic web 3 to further processing stations, such as cutting and stretching devices.
• Roll between the two trigger pairs 1, 1; 2, 2, the device according to the invention for drying plastic webs is arranged, which has a first, tubular nozzle 4 with a plurality of outlets 4a and a second,
• each nozzle 4, 5 is directed to a respective main side of the plastic sheet 3. It should also be noted that the two nozzles 4, 5 with respect to the conveying direction of the
• plastic web are offset from each other, so that the nozzle 4 is further downstream.
• FIG. 1A also shows that the tubular nozzles 4, 5 extend over the entire width of the plastic sheet 3.
• FIG. 1A shows that a tubular nozzle on each of the two main sides of the plastic web.
• a plurality of nozzles can be provided, with at least one nozzle on one side of the plastic web forming a group together with at least one nozzle on the other side of the plastic web.
• the tubular nozzles with several 5 outlets several small nozzles with one outlet each could also be provided, which are arranged in a row or in a suitable pattern.
• the nozzles 4, 5 are supplied with compressed air from a compressed air source, not shown, via a control device, not shown, in such a way that the
• Section 3a of the plastic web 3 conveyed between the nozzles is set into oscillation (vibration). This can be done by continuously blowing from both sides, taking into account the web tension and the dead weight and the rigidity of the plastic web, or by switching the individual nozzles on and off in a time-controlled manner, or by blowing on the plastic web with
• the cross section of the nozzle outlets or the blowing angle with respect to the plastic web can be adjusted to control the nozzle air flow. Due to the vibrations that are generated with the air nozzles 4, 5 in section 3a of the plastic web, water located on the web surface 0 is thrown off the web very quickly (represented by water drops 18) and the plastic web is thereby completely dried. The water droplets 18 which have been thrown off impinge on the drain plates 7 located behind the nozzles, which are bent towards the conveying path of the plastic web 3 in such a way that at their upper and lower ends downstream or upstream from the nozzles 4,
• the air flow from the nozzles 4, 5 sets the plastic web in oscillations that are O several hundred Hertz, with a particularly good drying Efficiency sets when the vibration frequency of the plastic sheet is between 1 kHz and 20 kHz.
• a two-part housing 9 is provided made of a material with good sound insulation effect, which surrounds the nozzles 4, 5, the drain plates 7 and the suction pipes 8 and only narrow slots Passing the plastic sheet 3 leaves open.
• the drain plates 7 by means of
• I O bolt 10 or the like to be attached to the inner walls of the housing 9, whereby one can dispense with a separate assembly of the drain plates 7.
• the vibration of the plastic web 3 also depends on the tensile stress that the web between the
• the tension can be controlled by correspondingly controlling the drive of at least one of the pairs of draw rollers 1, 1; 2.2 can be varied.
• a tension sensor 1 1 is provided in the embodiment shown, the output signal of which for controlling the pull roller pairs 1, 1; 2,2 or the air flow from the nozzles 4, 5 can be used.
• 10 1 1 is shown as a separate component for reasons of clarity; in practice, however, it will be installed in the shaft or hub of a draw-off roller or in the drive of the pairs of draw-off rollers.
• FIG. 2 an embodiment of the invention 15 is shown schematically in front view, from which an alternative arrangement of the nozzles emerges.
• Three tubular nozzles 15 with their longitudinal axes in the conveying direction (see arrow) of the plastic web 3 are arranged at a distance from one another. Shown in broken lines - and lying below the first nozzle group with the nozzles 15 with respect to the drawing plane - three further tubular nozzles 14 are arranged with their longitudinal axes in the OK conveying direction of the plastic web 3. Between the nozzles 14 and The plastic web 3 is passed through nozzles 1 5. The nozzles 14 are offset from the nozzles 1 5 transversely to the conveying direction of the plastic web.
• one nozzle 14 forms a nozzle group with an opposite nozzle 15, a gap being formed between the nozzles of a group for moving the plastic web through.
• the nozzles 14 are connected with a compressed air line 1 3 to a control device 12, which in turn is connected via a line 16 to a compressed air source, not shown.
• the nozzles 15 are connected to the control unit 12 with a compressed air line 13 '.
• a tension sensor 11 is connected to the control unit 12.
• the function of the control unit corresponds to that explained with reference to FIG. 1.
• the remaining parts of this embodiment of the device for drying plastic sheets according to the invention are the same as in the first embodiment according to FIG. 1 and have been omitted in FIG. 2 for reasons of clarity.
• Fig. 3 shows schematically in front view a further embodiment of the invention, in which three tubular nozzles 25 lie with their longitudinal axes transverse to the conveying direction (see arrow) of the plastic sheet 3 in one plane. Shown in broken lines - and lying in a plane below that of the nozzles 15 with respect to the drawing plane (which can be thought of as the transport plane of the plastic web 3) - three further tubular nozzles 24 are arranged with their longitudinal axes transverse to the conveying direction of the plastic web 3. The nozzles 24 are offset relative to the nozzles 25 against the conveying direction of the plastic web 3. It is provided that corresponding nozzles 24, 25 can be switched on and off in pairs in order to be able to pass plastic webs of different widths between the pairs of nozzles without making any manual changes to the nozzle configuration.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Molecular Biology (AREA)
• Drying Of Solid Materials (AREA)
• Treatment Of Fiber Materials (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

Country Status (8)

Cited By (1)

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• 2001
  • 2001-10-15 JP JP2002536482A patent/JP2004510949A/ja not_active Withdrawn
  • 2001-10-15 AU AU2001291472A patent/AU2001291472A1/en not_active Abandoned
  • 2001-10-15 BR BR0116789-8A patent/BR0116789A/pt not_active IP Right Cessation
  • 2001-10-15 KR KR10-2003-7005315A patent/KR20030059195A/ko not_active Application Discontinuation
  • 2001-10-15 WO PCT/AT2001/000332 patent/WO2002033337A1/de not_active Application Discontinuation
  • 2001-10-15 EP EP01971473A patent/EP1327115A1/de not_active Withdrawn
  • 2001-10-15 RU RU2003114428/06A patent/RU2003114428A/ru not_active Application Discontinuation
  • 2001-10-15 US US10/399,349 patent/US20040040175A1/en not_active Abandoned

Non-Patent Citations (1)

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