Method for preparing for a change of material in an extrusion device for a film machine

Patent metadata

Field	Value
Publication number	US-11267181-B2
Application number	US-201615561822-A
Country	US
Kind code	B2
Filing date	May 10, 2016
Priority date	Jun 8, 2015
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

The above object is solved by means of a method comprising the features as described herein as well as an extrusion device comprising the features as described herein. Further features and details of the invention follow from the depending claims, the description and the drawings. It goes without saying that features and details, which are described in connection with the method according to the invention, shall thereby also apply in connection with the extrusion device according to the invention and in each case vice versa, so that, with regard to the disclosure, reference is or can always be mutually made, respectively, to the individual invention aspects.

First claim

The invention claimed is:

1. A method for preparing for a change of material in an extrusion device for a film machine comprising two feed units for feeding feedstock to an extruder, comprising the following steps which are carried out by a control device as soon as a request to change the material is identified:
monitoring a production order and predetermining an end of the production order of the extrusion device automatically by calculating a remaining production time based on a remaining quantity of the production order,
specifying a reduced changing filling level for each feed unit, and
maintaining a filling level of each feed unit at the reduced changing filling level for a further production with the extrusion device,
wherein the control device identifies the end of the production order and uses the end of the production order as a basis for further regulation of the method, and the control device makes the specification of the reduced changing filling level for each feed unit on this basis, wherein the changing filling level is reduced with regard to a regular operating filling level inside each respective feed unit,
wherein a lowering time, which is required by the further production for lowering the filling level to the changing filling level, for each feed unit is determined after predetermining the end of the production order, and the reduced changing filling level is specified, when a remaining time to the end of the production order is equal to the lowering time,
wherein the film machine comprises two feed units,
wherein a specific changing filling level is specified for each feed unit of the extrusion device, and wherein a lowering of a respective column of a corresponding feed unit of the two feed units starts at different points in time, if columns of the two feed units drop at different speeds.

2. The method according to claim 1 ,
wherein the filling level of each feed unit is increased in batches, when the filling level falls below the changing filling level.

3. The method according to claim 2 ,
wherein the increase of the filling level in batches is made with a single refilling thrust, which refills less feedstock than an operating thrust during a normal production operation of the extrusion device.

4. The method according to claim 2 ,
wherein at least a volume or a weight of feedstock, which corresponds to the changing filling level in each feed unit, has a refilling ratio of between 1:1 and 2:1 with at least a volume or a weight of the feedstock of a refilling thrust.

5. The method according to claim 1 ,
wherein a minimal filling level, which is smaller than the changing filling level, is specified at a defined point in time prior to the end of the production order, and the filling level of each feed unit is maintained above the minimal filling level for the further production with the extrusion device.

6. The method according to claim 1 ,
wherein a filling level signal is received by the control device in order to maintain the filling level.

7. The method according to claim 2 ,
wherein
the filling level of each feed unit is increased in a single refilling thrust, when the filling level falls below the changing filling level.

8. The method according to claim 6 ,
wherein
the filling level signal includes at least one of the following pieces of information:
weight of an at least partially filled weighing funnel of the respective feed unit,
filling level in a weighing funnel of the respective feed unit,
filling level in a down pipe of the respective feed unit, and
filling level in a feed container of the respective feed unit.

Assignees

• Windmoeller & Hoelscher

Inventors

• Avermeyer Ansgar
• Kulgemeyer Tobias

Classifications

• B29C48/286

  Raw material dosing · CPC title

• B29C48/2692 Primary

  Material change · CPC title

• B29C2948/9298

  Start-up, shut-down or parameter setting phase; Emergency shut-down; Material change; Test or laboratory equipment or studies · CPC title

• B29C48/92

  Measuring, controlling or regulating · CPC title

• B29C48/10

  flexible, e.g. blown foils · CPC title