WO2008107169A1 - Extrusion die for producing hollow profiles - Google Patents

Abstract

The invention relates to an extrusion die (2) for producing hollow profiles (3) with a calibrator located downstream, in particular a dual-belt calibrator (1), said die having die lips (11, 12) that delimit a discharge region for the discharge of a plastic moulding mass. According to the invention, at least one of the die lips (11 and 12) is heated by one or more heating elements (13 and 14).

Description

 Extrusion nozzle for the production of hollow chamber profiles

The invention relates to an extrusion die for the production of hollow chamber profiles with a downstream calibrator, in particular Doppelbandkalibrator having nozzle lips which define an exit region for the exit of a plastic molding composition.

State of the art

Hollow profiles made of plastic are often used in facade technology or z. B. used for rafterless rooflights in roofs and walls. For this purpose, it is also known to produce the hollow chamber profiles of an impact-resistant, weather-resistant plastic such as polycarbonate.

One possible method for the production of such hollow-chamber profiles is described, for example, in EP 0 484 721 A2. They consist of two flat, one or both sides smoothed outer walls and connecting webs. she are made by extrusion of two outer sheets forming sheets of thermoplastic material, the two moving in the withdrawal direction, heated to a temperature in the thermoplastic state region of the plastic heated endless belts of a Doppelbandkalibrators and by simultaneous extrusion of a plurality of webs in the form of strands of thermoplastic material which are produced by a shaping extrusion die. The two outer walls are combined with the webs in the form of strands within the Doppelbandkalibrators to form a hollow chamber profile plate. The plastic molding compound itself is in turn produced in an extruder and supplied by the respective molding extrusion nozzle with pressure and pressed from this.

But it is also possible to produce the entire hollow profile by an extrusion die, in which case the extrusion die has a plurality of slots, which are formed according to the cross section of the hollow chamber profile. Since this is not a solid profile with a uniform cross-section, but a hollow chamber profile, which is constructed like a lattice in cross-section by means of the webs, problems can arise in the forming extrusion nozzle with regard to an addition of the thermal expansions, e.g. At nodes of the webs more mass is present, as in the area of the web walls. As a result, the dimensions of the die lips may be adversely affected during extrusion, i. it can bulges and therefore inaccuracies in the hollow profile shape due to uneven heat effects occur.

task

Proceeding from this, the present invention has the object to provide an extrusion die, which has a very homogeneous temperature profile when extruding hollow chamber profiles, so that on the one hand the production of dimensional mass as accurate as possible hollow chamber profiles and on the other hand the longest possible life of the extrusion die are guaranteed. Solution of the task

To achieve this object, at least one of the nozzle lips is heated by one or more heating element (s).

In particular, the measure, namely to design the heat output of the heating elements spatially differently adjustable, has the great advantage that different heat quantities can be provided especially at crossing points or thickening points of the profile webs, so that it is possible with such heating elements, predetermined areas of the cross-sectional profile of the extrusion die to influence for the hollow chamber profile to be produced with respect to their working temperatures to the effect that the respective extrusion lip practically has an approximate isothermic character.

According to a further measure of the invention, it is advantageous that the locally different heating powers are selected such that it is higher in areas with quantitatively higher throughput of plastic molding compound than in areas with quantitatively lower throughput of plastic molding compound, wherein for the higher throughput of plastic molding compound all webs and / or crossing points of the hollow chamber profiles to be produced come into question.

The individual heating elements, in particular heating cartridges, are preferably used in the front region in the upper and / or lower die lips parallel to the melt flow direction. Here, individual holes are provided, in which the individual heating elements can be used interchangeably. In this way, by appropriate alignment and influence of the arrangement of the heating element on frame slots, webs or the like. precise outlet areas different and selectable tempering. It should also be remembered that the matrices themselves, in particular the core, are provided with corresponding heating elements in order to temper the exact areas, crossing points, diagonal slots differently during the extrusion process in selectable areas.

Also, depending on the profile cross-section of the extrusion die, it is advantageous to provide a plurality of holes for receiving a plurality of heating elements in the upper and / or lower die lip in the vicinity of the exit region for the outlet of the plastics molding compound, the bores being parallel to the melt flow direction of the hollow chamber profiles should be lost.

Finally, it is in accordance with the present invention is advantageous if the heating cartridges are arranged individually or in groups interchangeable and controllable or adjustable, which facilitates assembly.

figure description

Further details and advantages of the present invention will become apparent from the following description of a preferred embodiment in conjunction with the drawings; show it

Fig. 1 is a schematic side view of an extrusion die, the

Inlet region of a Doppelbandkalibrators is arranged,

2 shows an enlarged detail "II" shown in FIG. 1,

Fig. 3 shows an extrusion nozzle in perspective and

4 shows an enlarged detail "IV" according to FIG. 3.

In Fig. 1, the principle of a Doppelbandkalibrators is schematically shown in side view, to which an extrusion die 2 of a not shown in detail and per se known extruder plant follows, from which fed a suitable plastic molding compound in plasticized form of the extrusion die 2 under pressure and thus from this is pressed in the form of a hollow chamber profile 3, as shown in FIG. 2.

The Doppelbandkalibrator 1 is similar to a double press, constructed of two on drums 4 - 7 mounted closed endless belts 8 and 9, between which in a nip 10, the respective hollow chamber profile 3 is calibrated when passing through the nip 10.

The extrusion nozzle 2 has an upper and a lower nozzle lip 11 and 12 in the outlet region for the exit of the plastic molding material heating elements 13 and 14 are arranged distributed parallel to a melt flow direction 15 across the width. In this case, the individual heating elements 13, 14 distributed to the full width individually or in groups controlled at the front and parallel to the melt flow direction 15 in the upper and / or lower die lip 11, 12 may be used.

In this case, they can be aligned correspondingly to matrices 18 to 20 arranged between the die lips 11, 12 and / or to frame slots 21 and diagonal slots 22 to 24 or webs 25.

Furthermore, it should be within the scope of the present invention that the heating elements 13, 14 can also be used, preferably parallel to the melt flow direction 15, in the dies 18 to 20 of the middle cores.

In this way, it is ensured that nevertheless over the bores 16 and 17, which are arranged approximately transversely to the melt flow direction 15 in the extrusion die 2, a production of overpressure and / or negative pressure is ensured. It is precisely this combination is of particular importance in the present invention that the holes 16, 17 still ensure a supply of negative air pressure or overpressure when extruding hollow chamber profiles.

With the nozzle lips 11 and 12 can in the present embodiment, as shown in enlarged in Fig. 4, a hollow chamber profile plate 3 of several contiguous Profilsträngeπ (shown only profile strands 3.1 - 3.3) of the same cross section are produced, with individual, juxtaposed separately narrower hollow chamber profile plates also possible are.

The upper die lip 11 has a series of grid-like dies, three of which are shown in FIG. 4 and designated 18-20. Own here the lattice-like matrices 18-20 respectively frame slots 21, two diagonal slots 22 and 23 and a central slot 24, wherein adjacent matrices, such as 3.1 and 3.2, by a relative to the slots 21 - 24 thicker web slot 25 are interconnected.

Both at the crossing points designated 26, where the diagonal slots 22 and 23 and the central slot 24 meet, as well as in the areas of the webs 25 in the production of the hollow chamber profile plates 3 a larger amount of plastic molding compound is extruded than through the other narrower slits. As a result, the plastic molding compound at the webs 25 and the crossing points 26 can deliver or lose a significantly larger amount of heat to the upper or lower nozzle lip 11 or 12 than, for example, the other narrower slots. The result is that possible temperature-related faults can occur in both the dies and / or the die lips 11 and 12.

This can also be a partially different flow speed of the plastic molding compound, which should be avoided. Of course, the same applies, for example. for the region of the lower left corner of the die 18, where a crossing point 27 is present as a thickening, namely from the diagonal slot 22 and the lower left corner of the here U-shaped frame slot 21st

In order to obtain here a selectable different temperature distribution in the entire outlet region of the two die lips 11 and 12, a plurality of heating elements 13 and 14 are provided over the width of the extrusion die 2.

Overall, with the inventive extrusion die an economical solution for the production of hollow chamber profile plates with a Doppelbandkalibrator shown in which not only their life is increased by the use of multiple heating elements directly in the exit region of the die lips parallel to the melt flow direction 15, but the As a result, even the highest demands with regard to dimensional accuracy and surface quality of the hollow chamber profile plates produced thereby are met.

LIST OF REFERENCE NUMBERS

Claims

claims 1. extrusion nozzle for the production of hollow chamber profiles with a downstream calibrator, in particular Doppelbandkalibrator having nozzle lips which define an exit area for the exit of a plastic molding compound, characterized, in that at least one of the nozzle lips (11 or 12) is heated by one or more heating elements (13 or 14). 2. Extrusion nozzle according to claim 1, characterized in that its upper (11) and lower (12) die lip is heated by at least one heating element (13, 14). 3. Extrusion nozzle according to claim 1 or 2, characterized in that the heating elements (13, 14) are arranged in the exit region of the plastics molding compound. 4. extrusion die according to claim 1 or 2, characterized in that the heating power through a plurality of juxtaposed heating elements (13 and / or 14) distributed over the width of the die lips (11 and / or 12) allows an optionally local different tempering. 5. extrusion die according to claim 4, characterized in that the locally different heating powers are selected such that they in Areas with a higher throughput in terms of volume of plastic molding compound is higher than in areas with a quantitatively lower throughput of plastic molding compound. 6. extrusion nozzle according to claim 4, characterized in that webs (25) and / or crossing points (26; 27) of the hollow chamber profiles (3) to be produced are areas with a quantitatively higher throughput of plastic molding compound. 7. Extrusion nozzle according to at least one of claims 1 to 6, characterized in that the heating elements (13, 14) are designed as heating cartridges. 8. Extrusion nozzle according to claim 7, characterized in that the plurality of heating cartridges (13, 14) are inserted approximately parallel to the melt flow direction (15) of the plastics molding compound or approximately perpendicular to the nozzle outlet into the nozzle lips (11 and / or 12). 9. extrusion die according to at least one of claims 1 to 8, characterized in that a plurality of heating cartridges (13, 14) in the upper die lip and / or lower die lip (11, 12) distributed over the width spaced from each other, wherein individual or one Plurality of heating elements (13, 14) individually or in groups can be controlled. 10. extrusion die according to at least one of claims 1 to 9, characterized in that the electrical, independent of each other Heating element (13, 14) can be controlled separately from the outside. 11. Extrusion nozzle according to one of the preceding claims, characterized in that in the upper and / or lower die lips (11, 12) at least one bore (16 or 17) for receiving the Heating cartridge is provided. 12. Extrusion nozzle according to at least one of claims 1 to 11, characterized in that individual or a plurality of heating elements (13, 14) in matrices (18, 19 and / or 20) is / are used, which are aligned in particular parallel to the melt flow direction (15) and individually or in groups can be controlled. 13. Extrusion nozzle according to one of the preceding claims, characterized in that the heating elements (13, 14) are arranged individually or in groups exchangeable.