Blown film extrusion device and method for controlling the temperature

Abstract

The invention relates to a blown film extrusion device with a blow head and with an insulation, which comprises a heat resistance for thermal insulation of the blow head in relation to the outer ambient air, wherein the blown film extrusion device comprises elements for controlling the heat resistance.

Claims

1. A blown film extrusion device comprising: a blow head configured to extrude blown film; and an adjustable thermal insulation structure directly adjacent to at least a portion of an outer sidewall of the blow head to provide selective thermal insulation of the blow head in relation to ambient air, the adjustable thermal insulating structure comprising: at least one insulating air gap chamber thermally contacting the blow head configured to extrude the blown film; and at least one flap, movably mounted between an insulation position closing the insulating air gap chamber to ambient air and a cooling position opening the insulating air gap chamber to ambient air, heat transfer from the blow head being completely controllable by controlling access of ambient air into the insulating air gap chamber.

2. The blown film extrusion device according to claim 1, further comprising an electrically controllable blower that influences an air stream.

3. The blown film extrusion device according to claim 1, wherein the at least one flap comprises a plurality of flaps connected to one another via a motor-driven gear arrangement.

4. The blown film extrusion device according to claim 1, further comprising: a heater integrated in the blow head; and a temperature controller providing a first control signal for controlling a heat performance of the heater and a second control signal for controlling thermal resistance.

5. A method of temperature controlling of a blown film extrusion device, wherein the blown film extrusion device comprises: a blow head configured to extrude blown film, the blow head including a heater integrated therein; and an adjustable thermal insulation structure directly adjacent to at least a portion of an outer sidewall of the blow head to provide selective thermal insulation of the blow head in relation to ambient air, the adjustable thermal insulating structure comprising: at least one insulating air gap chamber thermally contacting the blow head configured to extrude the blown film; and at least one flap, movably mounted between an insulation position closing the insulating air gap chamber to ambient air and a cooling position opening the insulating air gap chamber to ambient air, heat transfer from the blow head being completely controllable by controlling access of ambient air into the insulating air gap chamber, and wherein the method comprises: controlling a heat performance of the heater; and controlling thermal resistance of the blown film extrusion device.

6. A blown film extrusion device comprising: a blow head having an annular nozzle configured to extrude a blown film of melted thermoplastic; and an annular adjustable thermal insulation structure directly adjacent to at least a portion of an outer sidewall of the annular nozzle of the blow head to provide selective thermal insulation of the blow head in relation to outside ambient air, the annular adjustable thermal insulating structure comprising: at least one annular insulating air gap chamber that is in thermal contact with the annular nozzle of the blow head by annularly surrounding the blow head; and at least one flap annularly surrounding the at least one annular insulating air gap, the at least one flap being movably mounted between an insulation position closing the at least one annular insulating air gap chamber from the outside ambient air and a cooling position opening the at least one annular insulating air gap chamber to the outside ambient air, whereby heat transfer from the blow head is completely controllable by controlling access of the outside ambient air into the at least one annular insulating air gap chamber by moving the at least one flap.

Description

(1) Further advantages, features and details of the invention result from the subsequent description in which embodiments of the invention are described in detail in relation to the drawings. Thereby, the features described in the claims and the description can be essential for the invention each single for themselves or in any combination. It is shown schematically:

(2) FIG. 1 a first embodiment of a blown film extrusion device according to the invention,

(3) FIG. 2 the embodiment of FIG. 1 with the elements in a cooling position,

(4) FIG. 3 a further embodiment of a blown film extrusion device according to the invention,

(5) FIG. 4 the embodiment of FIG. 3 with the cooling flaps in a cooling position,

(6) FIG. 5 a further embodiment of a blow head extrusion device according to the invention,

(7) FIG. 6 the embodiment of FIG. 5 with the cooling flap in a cooling position,

(8) FIG. 7 a further embodiment of a blown film extrusion device according to the invention,

(9) FIG. 8 the embodiment of FIG. 7 with the cooling flap in a cooling position,

(10) FIG. 9 a further embodiment of the blown film extrusion device according to the invention,

(11) FIG. 10 an embodiment of an insulation according to the invention,

(12) FIG. 11 a further embodiment of a cooling flap and

(13) FIG. 12 the embodiment of FIG. 11 with the cooling flap in a cooling position.

(14) FIGS. 1 and 2 show a first embodiment of a blown film extrusion device 10 according to the invention. This is assembled about a blow head 100, wherein hereby a carrier structure 30, not described in detail, generates the assembly in a shown manner. Thereby, an insulating gap 40 is configured between the insulation 20 and the blow head 100. The FIG. 1 shows single elements 22 for controlling the heat resistance in form of cooling flaps 24 in the insulating position IP while FIG. 2 shows all cooling flaps 24 in the cooling position KP. With this embodiment the cooling occurs by heat convection and heat radiation.

(15) The FIGS. 3 and 4 schematically show a cross section of the embodiment of FIG. 1 and FIG. 2. In the FIGS. 3 and 4 the blow head 100 and the elements 22 configured as cooling flaps 24 are shown in a schematic cross section. With schematic arrows the heat convection KO and the heat radiation ST are shown in the cooling gap 40. If by flapping of the cooling flaps 24 the cooling flap 24 is moved from the insulating position IP into the cooling position KP according to FIG. 4 a heat exposure can occur by convection KO and heat radiation ST. Further, the axis of rotation or the opening axis 25 of the cooling flap 24 can be recognized.

(16) In the FIGS. 5 and 6 an embodiment of the cooling flaps 24 of the elements 22 can be recognized, which enable a stack effect. Thus, a first cooling flap 24 is assembled axially on the lower side and the second cooling flap 24 is assembled axially on the other side. In the open state, meaning in the cooling position KP, according to FIG. 6 a stack effect evolves which positively affects the heat exposure by convection. Additionally, for support and for generating of a forced convection a blown device 50 is intended.

(17) Likewise, FIGS. 7 and 8 show a further embodiment of a blown film extrusion device according to the invention. Hereby, a telescopic structure of the cooling flap 24 of the element 22 is provided so that by an axial displacement of an outer cylinder sleeve relative to an inner cylinder sleeve a reduction of the axial extension of the insulation 20 is provided and therewith an opening is released. Therewith, again heat radiation ST and convection KO can escape from the blow head 100 or from the insulation gap 40.

(18) FIG. 9 shows a further solution of a blown film extrusion device 10 according to the invention, by which within the insulation gap 40 single temperature devices 42 are assembled as possibilities for elements 22 within the insulation gap 40. The elements can for example be heating bands flown through with temperate oil or electrically controlled Peltier elements.

(19) FIG. 10 schematically shows a possible sandwich structure of the insulation 20, wherein within this insulation 20 an insulation material 26 is assembled. This is for example a so called aerogel mat. Ideally, the inner side of the sandwich structure should be completely thermally separated from the outer side so that no heat bridges between the inner side and the outer side occur.

(20) The FIGS. 11 and 12 show a further embodiment of a possible cooling flap 24 of the elements 22. This is configured in two parts so that by opening via an opening axis 25 via a folding axis 23 a reduction of the geometric area extension of the cooling flaps 24 can occur. Therewith, also in cramped conditions a possibly high opening cross sectional area is provided in order to achieve a possibly high cooling capacity.

(21) The description of the previous embodiments describes the present invention only within the scope of examples. Naturally single features of the embodiments as far as technically meaningful can be combined with one another without leaving the scope of the present invention.

LIST OF REFERENCE CHARACTERS

(22) 10 Blown film extrusion device 20 Insulation 22 Element for controlling the thermal resistance 23 Folding axis 24 Cooling flap 25 Opening axis 26 Insulation material 30 Carrier structure 40 Insulation gap 42 Thermal regulation device 50 Blower device 100 Blow head IP Insulation position KP Cooling position KO Convection ST Radiation