Adjusting device and method for controlling an exit thickness of a nozzle exit gap of a flat film machine

Abstract

The invention relates to an adjusting device (10) for controlling a discharge thickness (AD) of a nozzle discharge slot (110) of a flat film machine (100), comprising a plurality of adjusting bolts (20) for carrying out an adjusting movement for changing the discharge thickness (AD), wherein the adjusting bolts (20) comprise an adjusting region (SB) between a closing end position (SE) and an opening end position (OE), wherein further starting from the opening end position (OE), the adjusting region (SB) comprises a basic stroke path (BH) for a basic adjustment of the discharge thickness (AD) and, starting from the closing end position (SE), comprises a process stroke path (PH) for process controlling of the discharge thickness (AD).

Claims

1. A method for controlling a nozzle discharge slot of a flat film machine with an adjusting device for controlling a discharge thickness of a nozzle discharge slot of a flat film machine, comprising a plurality of adjusting bolts for carrying out an adjusting movement for changing the discharge thickness, wherein the adjusting bolts comprise an adjusting region between a closing end position and an opening end position, wherein further starting from the opening end position, the adjusting region comprises a basic stroke path for a basic adjustment of the discharge thickness and, starting from the closing end position, comprises a process stroke path for process controlling of the discharge thickness, comprising the following steps: adjusting a starting control value for the discharge thickness on a plurality of adjusting bolts by movement along the basic stroke path; controlling the discharge thickness based on a preset value by moving the plurality of adjusting bolts along the process stroke path; wherein the adjusting device performs both the adjusting and the controlling using the same adjusting bolt from the plurality of adjusting bolts at a respective local position.

2. The method according to claim 1, wherein after the adjusting movement of the discharge thickness along the basic stroke path, the end position of this adjusting movement is stored as the starting position for the subsequent controlling movements of the adjusting bolts.

3. The method according to claim 1, wherein the adjusting movement and the controlling movement are at least partially performed in parallel in time.

4. The method according to claim 1, wherein the adjusting movement takes place without clearance or at most with 0.1 millimeter clearance.

5. The method according to claim 1, wherein at least the adjusting movement or the controlling movement takes place at least in sections locally with a selection of adjacent adjusting bolts.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) Further advantages, features and details of the invention will be apparent from the following description, in which embodiments of the invention are described in detail with reference to the figures. In this connection, the features mentioned in the claims and in the description may each be essential to the invention individually or in any combination. The figures schematically show:

(2) FIG. 1 an embodiment of a flat film machine with an adjusting device according to the invention,

(3) FIG. 2 the embodiment of FIG. 1 in a detailed view of the nozzle discharge slot,

(4) FIG. 3 the embodiment of FIG. 2 with a smaller nozzle discharge slot,

(5) FIG. 4 the embodiment of FIGS. 1 to 3 before the clearance free adjustment of adjusting bolts,

(6) FIG. 5 the embodiment shown in FIG. 4 with adjusting bolts set free of clearance,

(7) FIG. 6 a representation of an adjusting bolt with an adjusting region,

(8) FIG. 7 the representation of the movement of the adjusting bolt along the basic stroke path and

(9) FIG. 8 the representation of an adjusting bolt in motion during the process controlling.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

(10) FIG. 1 schematically shows a flat film machine 100. The melt is discharged via a nozzle discharge slot 110, which cools as a film track 200 on a large casting roller or cooling roller. Further conveying of the cooled film track 200 is shown here with an arrow and can lead, for example, to a winding reel. With the aid of an adjusting device 10, it is possible to vary the discharge thickness AD of the nozzle device 110, so that influence can be exerted on the thickness profile of the melt or the thickness profile of the film track 200. It can also be clearly seen here how the adjusting device 10 can refer to a corresponding storage device 30, in which the storage of specific relative positions of the individual adjusting bolts 20 can occur.

(11) FIGS. 2 and 3 show a top view of the nozzle discharge slot 110 of the flat film machine 100. With the aid of the adjusting device 10, all individual adjusting bolts 20 can now be specifically controlled with regard to their length extension. For example, in order to set a first reduced discharge thickness AD, starting from FIG. 2, the temperature can be increased for thermal bolts as adjusting bolts 20 until the increased extension of the individual adjusting bolts 20 at increased temperature has reduced the nozzle discharge slot 110 to the reduced discharge thickness AD according to FIG. 3.

(12) FIGS. 4 and 5 show the possibility of achieving an adjustment free from clearance. Thus, part of the adjusting movement can imply to bring the individual adjusting bolts into contact with the upper nozzle lip above the nozzle discharge slot 110. Starting from FIG. 4, the adjusting bolts 20 are thus applied to the nozzle lip of the nozzle discharge slot 110 from above, as it were, for example with a defined pre-tensioning force, as shown in FIG. 5.

(13) FIGS. 6, 7 and 8 schematically show the possibilities of the basic stroke path BH and the process stroke path PH during the adjusting movement and the controlling movement. FIG. 6 shows the adjusting bolt 20 in its two extreme positions, namely the opening end position OE and the closing end position SE shown in dashed lines. Thus, the entire region of movement is given as the adjusting region SB, which is designed in particular to be smaller than approx. 2 mm, but larger than approx. 1 mm. For the first adjustment of the flat film machine 100, a movement of the adjusting bolt 20 from the opening end position OE along the basic stroke path BH takes place, as shown in FIG. 7. Once this initial adjustment has occurred, actual process controlling can now be performed by opening and closing accordingly within the process stroke path PH of the adjusting bolt 20 as shown in FIG. 8.

(14) 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

(15) 10 adjusting device 20 adjusting bolt 30 storage device 100 flat film machine 110 nozzle discharge slot 200 film track AD discharge thickness SB adjusting region SE closing end position OE opening end position BH basic stroke path PH process stroke path