DE2142508A1 - DEVICE FOR PREVENTING DEFLECTION AND MAINTAINING RUNNING ACCURACY OF HEATED ROLLERS OF A FILM STRETCHING DEVICE - Google Patents

Description

2U2508

Device to prevent the deflection and to maintain the concentricity of heated Stretching rollers of a film stretching device

The invention relates to a device for. Impede the deflection and to maintain the concentricity of heated stretching rollers of a polishing stretching device.

State of the art

From the German Offenlegungsschrift No. 1 504 503 is one Stretching device for thermoplastic plastic webs is known, in which the longitudinal stretching is carried out by a roller stretching stretch he follows. The film to be stretched is with the direction of passage of the plastic web from top to bottom introduced between the individual stretching rollers. The vertical arrangement of the longitudinal stretching steps makes threading the plastic sheet to be stretched is made much easier. For this purpose, the longitudinal stretching stages, which are made up of a series of group-wise combined and parallel rollers, see above designed that in their inoperative position they free fall through the supplied plastic sheet between the roller groups up to the transport device. Only when the plastic sheet is in this Way has been threaded, the roller groups brought into their effective position, in which they stretch longitudinally through different circumferential speeds carry out the plastic sheet.

From the German Auslegeschrift No. 1 277 552 is also

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if a roller stretching distance is known, for the purpose the threading of the plastic web every second stretching roller is moved upwards.

The stretching rollers shown here are used as drag rollers trained, they have no drive of their own. After threading the plastic sheet and after moving it together of the stretching rollers, these are carried along by the film to be stretched.

The prior art stretching rollers can each be heated separately.

Criticism of the state of the art

It has been shown in practice that the roles of such Roller stretching when the stretching process is switched off and in the extended state or in In the event of a malfunction, bend upwards or lose their true running accuracy.

The cause of the sagging of the individual stretching rollers or for the loss of concentricity is included therein look for that .the stretching rollers heated to approx Stand still gives off more heat at its top than at their underside. This results in greater heating of the roller jacket on the upper side than on the underside and thus an upward deflection. In addition, the stretching roller loses its concentricity because of the roller shell is subjected to a different expansion. Due to the different expansions arise also tensions in the roller shell, which leads to material fatigue and thus to a relatively short service life such forging rolls leads.

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The distance from stretching roller to stretching roller in "division of labor the roller stretching distance must be kept as short as possible in order to keep the width indentation of the plastic film as small as possible during the longitudinal stretching. In practice this means that there may only be a distance of 0.5 mm between the individual stretching rollers, if one considers the width indentation, i.e. the contraction of the film in its width during the stretching process in wants to keep it to a reasonable level.

So if only the distance from stretching roller to stretching roller 0.5 mm, the deflection of each is made Stretching rollers, caused by the above-mentioned causes, in so far as very disturbing noticeable because the stretching rollers jam in each other when moving together and thus destroy the film in between or the film to be stretched Plastic sheeting can no longer be taken.

When the concentricity of the individual stretching rollers is no longer given, there are also different stretching ratios in the film, which in some places Leads to weakening or to the film being unsuccessful.

Object of the invention . ...

It is therefore the job of the. Successful. _? To create a device with which the above-mentioned disadvantages are avoided, or by means of the .Beck process by moving apart, the.individual stretchers can be interrupted further, .without.a change, the stretching. occurs. . . .... ·. .. ... ■ '..'.

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"2H2508

Solution of the task according to the invention

The object of the invention is achieved in that the heated stretching rollers when the stretching process is switched off in the extended state by a Belt drive, which is guided around urn guide pulleys and tension pulleys, can be kept rotating.

According to a further feature of the invention it is provided that the belt drive drive rollers and tension rollers and that a belt drive depending on the setup of the roller recfc section in horizontal or vertical Level is movable.

Description of an application example

FIG. 1 of the accompanying drawing shows a roller stretching section, the individual stretching rollers 1 and 2 being moved apart are. The stretching rollers 1 are movable, while the stretching rollers 2 are fixed.

FIG. 2 shows the roller stretching section in the working position, with the plastic web to be stretched; 5 alternating wraps around rollers 1 and 2 by approx. 180 °.

A plastic film is inserted into the device according to FIG 3 inserted from top to bottom. Thereafter, the stretching rollers 1 by a device known per se in the drawing to the right against the inserted plastic film, so that this the stretching rollers 1 and 2 wrapped around about 180 °. At the same time, the movable part 14 of the belt drive for the Stretching rollers also moved to the right by a device not shown, so that the stretching rollers 2 of the V-belt 9 can no longer be driven. The drive the rcekrolling takes place when dis position after Pigur 2 oiugonoim'ien been

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2U25G8

is, through the film itself, from the roller stretching line by a device not shown and known per se, for example of two driven rollers, between which the film is held, consisting, pulled out-.

Before the actual stretching process can begin, however, the stretching rollers 1 and 2 must be heated to their predetermined temperature. The heating of the stretching rollers, which have a diameter of 40-80 mm, can take place by steam or oil in a manner known per se. If the stretching rollers stand still during the heating process, the heating of the stretching roller jacket at the top is significantly greater than at the bottom, which means also a larger expansion of the top of the back rollil - coat is done. Thus, as already mentioned, the individual stretching rollers or a deflection are obtained Inaccuracy in their concentricity. To remedy this deficiency, the invention provides two belt drives 14 and I5, whereby the stretching rollers 1 and 2 are set in rotary motion and thus a uniform heating of the ReckroHenmantels takes place.

The belt drive 14 shows deflection rollers 4 and a tensioning and drive roller 5-up. Around these rollers runs, for example, via not shown, arranged at the end of the rollers V-belt pulleys a V-belt 9. The auxiliary drive 14 can be moved in the direction of the stretching rollers 2 * and back by a known device. (See arrow 11).

The rigid belt drive I5 also has deflection rollers 6 'and a tension and drive roller 7. The drive .rollers 5 and 7 tension the V-belts 8 and 9 through the devices 10

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The stretching rollers 1 are also in the vertical plane by a device known per se, not shown moveable.

Functioning of the device according to the invention

The puncture catfish of the stretching device can be seen from FIG. The slide j5 does not happen shown clamping mechanism, for example consisting of two rollers / between which the film is held is and then comes to the stretching roller 1, which they around wraps around approx. 100 ° to the stretching roller 2, which wraps around it by approx. 180 °. During the wrapping process the film around the individual stretching rollers 1 and 2 is under the from a tensioning device, not shown high tension set and thus stretched.

If the film 5 ^{tears in the stretching device for} any reason, the stretching rollers 1 according to FIG. However, in order to ensure that the stretching rollers, which do not have their own drive, do not stand still in such a case, the stretching rollers 1 are driven against the rigid part 15 of a belt drive, which is automatically set in motion by limit switches (not shown) in such a case. The heated stretching rollers 1 thus rotate.

The moving parts of the opposite belt drive with its V-belt are synchronized with this process 9 driven against the Reekrollen 2 by a known device, not shown. It is thus ensured that the stretching rollers 2 are also subjected to rotation when threading a new roller conveyor or in the event of a disturbance will.

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• 2U2508

The arrow 11 indicates that the movable part 14 of the belt drive for the stretching rollers to the left or right can be driven.

The smaller rollers 12 and 15 ensure that the V-belt rests firmly against the stretching rollers 1 or »2 and thus a perfect transmission of the Torque can take place.

Advantages of the device according to the invention

The greatest advantage of the device according to the invention is to be seen in the fact that the belt drives 14 and 15 the stretching rollers 1 and 2 are also set in rotary motion when the stretching rollers are heated or a new one in a heated stretching device Foil is to be threaded, so basically when the stretching rollers 1 and 2 have moved apart.

This measure prevents the heated stretching rollers from emitting unevenly heat and thus a deflection of the individual stretching rollers or an uneven expansion of the stretching roller jacket he follows. "'

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Claims (1)

Claims Claim 2 Claim 5 claim Device to prevent sagging and to maintain concentricity of heated Ree rolls of a film stretching device characterized, that the heated stretching rods:, (l, 2) when the stretching process is switched off in the extended state by a belt (8.95 »around pulleys (4,6) and tensioning rollers (5, T) are kept rotating. Device according to claim 1, characterized in that the belt drive (14,15) through Fetch. (5 * 7) is driven. Device according to Claims 1 and 2 characterized, that the rollers (5j7) are designed as tension rollers. Device according to Claims 1 to J, characterized in that that the belt drive (14) depending on the setup of the roller stretching section in horizontal or vertical plane is movable. 3OS8.11 / 090 7 _{OR | QINAL}