Patent ID: 12208557

FIGS.1and2show schematically how a flat film machine100can be constructed. A discharge nozzle110with an upper and a lower nozzle lip forms a nozzle slot112from which material melt is discharged. This material melt solidifies and is thereby formed as the film track FB along the production direction PR (inFIG.1directed downwards). In order to vary the nozzle slot112with respect to its outlet width or outlet intensity, a plurality of adjusting means120are provided. These can be designed, for example, as thermal bolts, i.e. their length can be varied by the application of thermal energy. This makes it possible to provide more or less melt for the production of the film track FB in individual local partial regions. More melt leads to a thicker film track FB at this point, while less melt leads to a thinner film track FB.

A thickness profile DP can now be acquired over the entire width in the transverse direction QR, but at least in the edge sections RA explained later, with the aid of an acquisition module20. The acquisition module20is arranged here in the acquisition position EP, which can preferably be variably adapted to the actually produced format of the film track FB. The acquired thickness profile DP is now processed further in a comparison module30of the controlling device10and a profile deviation PA can be determined via a determination module40. Via the intervention module50, the controlling intervention can now be regulated back to the flat film machine100, so that the desired controlling result can influence the thickness profile DP in at least one edge section RA via the adjusting means120.

FIG.2shows a side view of the discharge nozzle110with the nozzle slot112. Here it can be clearly seen how a thermal extension of the adjusting means120against an abutment, which is not shown, reduces the nozzle slot112and thus also reduces the thickness of the film track FB at this point. The changed thickness profile can in turn be sensed via the acquisition module20and read into the controlling device10as feedback.

FIG.3shows schematically how such a thickness profile DP can look. In the middle section, a net region is shown which is considerably shorter than in reality and which shows the film product of the film track FB. Here, very narrow limits are given as a preset profile VP, which can also be used as a normal thickness regulation. Crucial for the present invention are the two edge sections RA on the left and right side of this net region. Here, for example, global preset profiles VP can be preset in order to avoid too thick spots and too thin spots in this edge section of the thickness profile DP. As can also be seen inFIG.3, the edge sections RA are first provided with a thick spot and then with a thin spot from the outside inwards. Only after this combination of thick spot and thin spot does the thickness profile DP transform into the continuous region of the net width of the film track FB.

FIGS.4and5show further possibilities of edge sections RA. Here, defined preset profiles VP are specified for individual partial sections of the respective edge section RA. Thus, a separate profile region is specified or permitted here for the respective thick spot and the respective thin spot, in which the maximum and the minimum of the thickness profile DP may move. Whereas inFIG.4the thickness profile DP moves within the specified limits of the preset profile VP, the thin spot according toFIG.5leaves the preset profile VP in a downward direction. This makes it possible to recognize a local profile deviation PA, i.e. a thin spot that is too thin in this case. A corresponding controlling intervention now makes it possible to provide more material melt at this point in order to ensure that this too thin spot is filled.

FIG.6shows a possible changing between a feed product EP and a follow-on product FP. Here it can be seen that the new format of the follow-on product is narrower, and thus also has a narrower net width as well as changed positions of the edge sections RA. For the correlation, an acquisition module20can leave the defined acquisition position EP and also move inwards in the representation in the example according toFIG.6, in order to be able to ensure the monitoring of the edge sections with a high degree of certainty.

FIG.7shows that after the flowable discharge from the nozzle slot112, a so-called neck-in of the film track FB occurs in the discharge section AA. Via the edge section and monitoring, this neck-in in the discharge section can also be monitored, namely as the temporal end of the edge section, i.e. when the thickness profile jumps to zero, i.e. the non-existence of the film track. Thus, a method according to the invention can be applied not only to the actual stability of the thickness, but additionally for a geometrical monitoring of the lateral edge sections and the correlation to the corresponding format.

The foregoing explanation of the embodiments describes the present invention exclusively in the context of examples. Of course, individual features of the embodiments can be freely combined with each other, provided that this is technically reasonable, without leaving the scope of the present invention.

LIST OF REFERENCE SIGNS

10controlling device20acquisition module30comparison module40determination module50intervention module100flat film machine110discharge nozzle112nozzle slot120adjusting meansFB film trackRA edge sectionEP feed productFP follow-on productEP acquisition positionAA outlet sectionQR transverse directionPR production directionDP thickness profileVP preset profilePA profile deviation