GB2381233A

GB2381233A - Cooling mandrel for films

Info

Publication number: GB2381233A
Application number: GB0207394A
Authority: GB
Inventors: Martin Annerer; Luck Frank Van
Original assignee: Sms Folientechnik & Co KG GmbH
Current assignee: Sms Folientechnik & Co KG GmbH
Priority date: 2001-10-24
Filing date: 2002-03-28
Publication date: 2003-04-30
Also published as: GB0207394D0; DE20117403U1

Abstract

A device for cooling extruded plastic film, in particular foam film, is constructed from a first part element (1, 2) and a second part element (3, 4, 5, 6, 7, 8). The first part element (1, 2) comprises a hollow profile (1) having at least two plates (2) and the second part element (3, 4, 5, 6, 7, 8) encloses the first part element (1, 2) and is connected to the latter. The second part element (3, 4, 5, 6, 7, 8) is constructed from at least two individual layers (3, 4) and is releasably connected to the first part element (1, 2) via adapters (8).

Description

COOLING MANDREL The invention relates to a device for cooling extruded plastic film, in particular foam film, which is constructed from a first part element and a second part element, wherein the first part element comprises a hollow profile having at least two plates and the second part element encloses the first part element and is connected to the latter.

In the production of plastic films, in particular for foam films, it is necessary to cool the extruded film in order to obtain a usable product. A cooling system, in particular a cooling mandrel, is used for this. The system"cooling mandrel"has various functions.

The cooling mandrel itself determines the final mass and quality of the film by the cooling of the supplied foam. Accordingly, the periphery of the cooling mandrel and the removable quantity of heat are crucial influencing parameters. At least in the case of PE foam films, a cooling ring, which cools the side of the foam film facing away from the cooling mandrel by cooling air, is attached around/outside the cooling mandrel. In contrast to PS foam film, cooling rings may not be attached to the die, since due to the significantly lower density and the expansion of the foam associated therewith, the latter emerges almost radially from the nozzle. Apart from the lack of space for nozzle-side attachment of an inner cooling ring, the cooling air would also blow the foam film back inadmissibly against the die.

In addition to calibration, the main task of the cooling mandrel is cooling of the foam film. Cooling mandrels are exchangeable, so that other dimensions may be produced. Cooling mandrels are currently mostly produced from aluminium, because only in this way may adequate heat removal be guaranteed. In order to be able to produce the cylindrical outer ring of the cooling mandrel, the latter is cast or centrifugally cast. The surface thus obtained is not of adequate quality, so that reprocessing is required. The surface is protected against corrosion at the same time. The coatings applied hitherto also guarantee a very high friction deficiency.

It is an object of the invention to increase the removable quantity of heat from the outer shell into the mandrel. An aluminium design of the outer shell may thus be dispensed with and significantly simplified production processes may be used.

The solution to this object is characterised in conjunction with the preamble of claim 1 in that the second part element is constructed from at least two individual layers and is releasably connected to the first part element via adapters.

There is no inner insulation in current cooling mandrels. Therefore, in the device of the invention, the second part element is provided with an insulating layer, which is preferably arranged between the adapters. Traditional insulating wool from building markets may be used here. Inner covering should take place due to the condition of the insulating wool, so that operators do not come into contact with the fine fibres and likewise they cannot be found later on the film. Furthermore, if a fault occurs, the plastic film may still be guided through the mandrel. Therefore, provision is made according to the invention to provide the insulating layer with a covering towards the hollow profile.

This covering may be realised via cylindrical pipes, wherein they do not necessarily have to consist of metal or non-ferrous metals, but plastic pipes could also be used here.

By way of further development, two adapters are coupled by means of rods. The adapters are provided to accommodate attachment elements, connecting elements or other functional elements, eyebolts or thrust screws are thought of here, which are screwed into bores.

The second part element is constructed from an inner and an outer tube, wherein the outer tube may be designed to be conical. The inner tube preferably comprises a metal sleeve, wherein a plastic sleeve is also conceivable. This sleeve is suitable for accommodating attachment elements, so that, for example thermocouples may be fixed and cooling water inlets and outlets attached. Provision is made for this to weld on nuts or to attach threaded bores.

At least one of the layers of the second part element is constructed as a helix, wherein the helix is produced from, for example, adhered plastic profiles. This guarantees that cooling medium or the like may be passed through the device.

One exemplary embodiment of the invention is shown in the accompanying drawing.

Figure I shows schematically a cooling mandrel of the invention. Round plates 2 are welded onto a hollow profile 1 and form the first part element to which the actual cooling mandrel is attached. A hollow profile 1 is therefore useful, since for certain foam films, cooling air is passed through the hollow profile into the die, to which the inner cooling air ring is attached.

The actual cooling mandrel, the second part element, comprises at least two individual layers and is attached to the first part element by means of an adapter 8. The insulating layer 5 prevents as far as possible the thermal transfer from the outer region of the second part element to the core of the device, the hollow profile 1 of the first part element, and the atmosphere. One of the layers 5 is constructed as a helix, wherein the helix is formed from adhered or welded-on plastic or silicone profiles. Of course, profiles made from metal or aluminium can also be used. A channel, through which a cooling medium may be passed, is thus produced.

In order to be able to simply exchange the second part element, the adapters 8 are connected to one another. Threads for eyebolts (crane transport) and thrust screws are provided on the adapters. In addition, small eyebolts should be able to be screwed-in, in order to possibly attach to them cable binders for fixing the cooling water hoses-if the round rods are not adequate for this.

The second part element comprises an outer tube 11, optionally conical, wherein the wall thickness does not necessarily have to exceed 5 mm. Here, equilibrium can be found between function-frictional forces and forces indicated by shrinkage of the film-and

mechanical manufacture-which wall thickness can still be sensibly clamped in a machine. Likewise, a metal sleeve is used as inner tube 10. There is the marginal condition here that thermocouples and cooling water inlets and outlets have to be connected, so that the shell must have either a certain minimum thickness for thread screwing-in or nuts may be welded on, which fix the thermocouple.

An insulating layer 5, which is sealed on the inside by a plastic pipe, is provided below the inner tube 11. Optionally, the insulation may also be enclosed on all sides.

The insulation is sealed towards the side. Like the flow channel for the water, a silicone profile may be used here as a lateral covering. The insulation may also be achieved by using a plastic pipe as inner shell (without additional insulation on the inside). The second part element is only screwed on the front side using the adapter 8, it rests on the rear adapter. An air gap for insulation is thus left between adapter wall and flow channel.

If the cooling mandrel, that is the second part element, is to be exchanged, the front adapter plate should thus be released and the second part element may be removed.

Further plates for adaptation may be welded onto the hollow profile 1. Rapid-closure couplings are attached in 2 directions on the plates, so that the cooling connections may be released rapidly. Likewise, couplings are then provided for the thermocouples.

For convenience, the reference numerals in Figure 1 designate the following parts :- 1 Hollow profile 2 Plate 3 First individual layer 4 Second individual layer 5 Insulating layer 6 Covering 7 Helix 8 Adapter 9 Attachment element 10 Inner tube 11 Outer tube

Claims

Claims: 1. Device for cooling extruded plastic film, in particular foam film, constructed from a first part element (1, 2) and a second part element (3,4, 5,6, 7,8), wherein the first part element (1, 2) comprises a hollow profile (1) having at least two plates (2) and the second part element (3,4, 5,6, 7,8) encloses the first part element (1, 2) and is connected to the latter, characterised in that the second part element (3,4, 5,6, 7,8) is constructed from at least two individual layers (3,4) and is releasably connected to the first part element (1, 2) via adapters (8).
2. Device according to claim 1, characterised in that the second part element (3,4, 5, 6,7, 8) has an insulating layer (5), which is preferably arranged between two adapters (8).
3. Device according to claim 2, characterised in that the insulating layer (5) is provided with a covering (6) towards the hollow profile (1).
4. Device according to claim 3, characterised in that the covering (6) is constructed from a plastic pipe.
5. Device according to claim 4, characterised in that two adapters (8) are coupled to one another, preferably via rods.
6. Device according to claim 5, characterised in that the adapters (8) are provided to accommodate attachment elements.
7. Device according to any one of claims 1 to 6, characterised in that the second part element (3,4, 5,6, 7,8) is constructed from an inner and an outer tube (10, 11).

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8. Device according to claim 7, characterised in that the outer tube (11) is designed to be conical.
9. Device according to claim 7, characterised in that the inner tube (10) comprises a metal sleeve, wherein the metal sleeve is suitable for accommodating attachment elements.
10. Device according to any of the preceding claims, characterised in that at least one of the individual layers of the second part element (3,4, 5,6, 7,8) is constructed as a helix (7), preferably made from adhered plastic profiles, in order to facilitate throughflow of a cooling medium.
11. Device for cooling extruded plastic film substantially as hereinbefore described with reference to the accompanying drawing.