DE102019116007A1 - Device for producing a plastic web - Google Patents

Abstract

The invention relates to a device for producing a plastic web (4), preferably a deep-drawing film or a plate, the device comprising a smoothing unit (2) with at least two rollers. According to the invention, it is provided that the surfaces of one or more rollers (7) with a contour are applied, which makes it possible to produce the plastic sheet (4) with at least two different thickness profiles, as well as a corresponding plastic film or plastic plate.

Description

Device for producing a plastic web, preferably a deep-drawing film or plate, the device comprising a smoothing unit with at least two rollers.

Plastic films and sheets for deep-drawn products and technical articles are often produced with the help of so-called smoothing units.

Deep-drawing foils and technical foils typically have a foil thickness in the range of 150-2500 µm, plates are between 1500 µm and 70 mm. All mass-produced plastics (PS, PVC, PP, PET, ...) but also special materials such as ABS, ASA, PA, PMMA, PC, ... can be found as materials. The tolerance range for the film thickness is usually +/- 2% and can extend up to +/- 5%, which means that a 300 µm film can have a tolerance range of +/- 6 to +/- 15 µm.

As a rule, a plastic melt is fed in via a slot nozzle. The calender itself absorbs this melt and calibrates the material from the nozzle. In addition, the melt is cooled and the calibrated state (surface, etc.) is frozen. A roll gap is formed from one roll of a calender to the next roll, which is to be adjusted depending on the material thickness to be achieved. Smoothing units are often designed as 3-roller smoothing units, so that there are two roller gaps between the three rollers. However, variants with only two rolls or a multi-roll calender with more than 3 calender rolls are also known.

Calender rolls can be designed as solid rolls or double-shell rolls. By means of special manufacturing processes in the roller production or by special constructions with regard to the "inner workings" (structural design of the cooling, the material transitions etc.) of the rollers, efforts are made to keep technical tolerances such as concentricity, cylindricity, parallelism, etc. in the µm range.

The object of the invention is to further develop a device in such a way that it is possible to manufacture plastic webs which have different film or board thicknesses within a web or plate produced.

The solution to the problem is characterized in connection with the preamble of claim 1 in that the surfaces of one or more rollers are provided with a contour which enables the plastic web to be produced with at least two different thickness profiles.

The device according to the invention is suitable, for example, for producing a film which enables the production of a hinged packaging, each with a base body and an associated lid.

According to a further development it is provided that the contour of the roller is provided with steps. This has the advantage that e.g. the area of the plastic sheet that is used for the lid of a hinged packaging is slightly thinner than the part for the base body.

These stages can also be mapped twice on a roller, which makes it possible to produce folding packaging twice next to one another.

According to a further development, the transition from one thickness profile to the other in the plastic web produced is designed to be as sharp-edged or as fluid as possible, which is why the rollers are designed with such transitions accordingly. This allows the transition in the plastic sheet or plate to be adapted to the desired requirements.

Further training courses are given in the subclaims.

Furthermore, the invention includes a plastic film or plastic plate which is produced by means of a smoothing device and comprises at least two different thickness profiles.

• 1 zeigt eine typische Glättwerksanlage und
• 2 eine der erfindungsgemäßen Walzen

A device according to the invention is shown schematically in the drawings:

• 1 shows a typical calender system and
• 2 one of the rollers according to the invention

1 shows a typical smoothing plant as it is used today for film extrusion. It shows an extruder 1 , in which the plastic is melted, and continuously for shaping via a slot nozzle to the calender 2 is fed. By means of the calender rolls 6th and 7th becomes the slide 4th calibrated to their desired thickness and connected by means of the cooling rollers 5 cooled and connected, here as an example, a thermoforming machine 3 supplied for further processing. Alternatively, the web can be wound up.

In 2 is a schematic representation of the possible embodiments of the offset rollers 7th reproduced. In 2a is a single-stage offset roller 7th shown showing a sharp transition 10 from a first stage 8th to a second stage 9 having.

In 2 B , is a roller 7th shown in which there is a change in the thickness profile twice. From the first stage 8th it goes to the second stage 9 and back to the first stage 8th back. The respective transition 10 is rounded in the embodiment.

In the representation according to 2c is a roller 7th also with three levels 8th , 9 shown. But here is the transition 10 from the first stage 8th to the outside step 9 executed fluently. Both the angle of the transition 10 as well as the transition itself, can be adjusted depending on the desired film properties and be edged or rounded accordingly.

The gradations and transitions in the roller 7th can therefore be selected individually depending on the application. More than just two or three transitions in the thickness profile can thus be realized and these transitions are repeated several times on one roller.

Through these different stages, plastic sheets or panels with different thickness profiles can be produced. As a rule, the two thickness profiles differ only in the range of fractions of millimeters, but to clarify the principle, the steps in the figures are shown greatly enlarged.

In addition to the use of the webs for hinged packagings already mentioned by way of example, other applications are conceivable.

List of reference symbols

1

Extruder

2

Calender

3

Thermoforming machine

4th

Plastic film or sheet

5

Chill rolls

6th

Smoothing rollers

7th

offset roller

8th

first stage in 7th

9

second stage in 7th

10

Transition from 8 to 9

Claims (7)

Device for producing a plastic web (4), preferably a deep-drawing film or plate, the device comprising a smoothing unit (2) with at least two rollers (6, 7), characterized in that the surfaces of one or more rollers (7) with a contour are acted upon, which makes it possible to produce the plastic sheet (4) with at least two different thickness profiles. Device according to Claim 1 , characterized in that the contour of the roller (7) is provided with steps (8, 9). Device according to Claim 2 , characterized in that the steps (8, 9) are mapped twice on the roller (7). Device according to Claim 2 or 3 , characterized in that a further profiling of the roller (7) is arranged in addition to the contour with steps (8, 9). Device according to Claim 2 , 3 or 4th , characterized in that the transition (10) from one thickness profile to the other in the plastic web (4) produced is as sharp-edged as possible. Device according to Claim 2 , 3 or 4th , characterized in that the transition (10) from one thickness profile to the other in the plastic web (4) produced is designed to be as fluid as possible. Plastic film or plastic plate that is produced by means of a smoothing unit and comprises at least two different thickness profiles.

Images