US 12,466,120 B2
Method and device for reducing variations in the ejection of a plastic melt
Andre Wieczorek, Leoben (AT); Walter Josef Koelbl, Rust (AT); and Peter Kromer, Vienna (AT)
Assigned to BC EXTRUSION HOLDING GMBH, Bad Oeynhausen (DE)
Appl. No. 17/793,933
Filed by BC Extrusion Holding GmbH, Bad Oeynhausen (DE)
PCT Filed Jan. 15, 2021, PCT No. PCT/EP2021/050847
§ 371(c)(1), (2) Date Jul. 20, 2022,
PCT Pub. No. WO2021/148329, PCT Pub. Date Jul. 29, 2021.
Claims priority of application No. 10 2020 101 387.6 (DE), filed on Jan. 21, 2020.
Prior Publication US 2023/0051629 A1, Feb. 16, 2023
Int. Cl. B29C 48/92 (2019.01); B29C 48/25 (2019.01); B29C 48/395 (2019.01)
CPC B29C 48/92 (2019.02) [B29C 48/2522 (2019.02); B29C 48/395 (2019.02); B29C 2948/92019 (2019.02); B29C 2948/92076 (2019.02); B29C 2948/92409 (2019.02); B29C 2948/9259 (2019.02); B29C 2948/926 (2019.02); B29C 2948/92885 (2019.02)] 4 Claims
OG exemplary drawing
 
1. A method for reducing fluctuations over time in discharge of a plastics composition when extruding plastics products, comprising:
melting plastics material in an extruder and supplying the plastics material to an extrusion die by way of one or more extruder screws arranged in the extruder; and
conveying a plastics composition along an extrusion axis by rotating the one or more extruder screws as pressure builds up; and
changing a rotational speed of the one or more extruder screws to keep constant a discharge of the plastics material at a transition region from the extruder to the extrusion die or in the extrusion die,
wherein changing the rotational speed of the one or more extruder screws comprises increasing and then decreasing, or vice versa, the rotational speed of the one or more extruder screws,
wherein the changing of the rotational speed is carried out within one revolution of the one or more extruder screws,
wherein a magnitude of a rotational-speed change associated with the changing of the one or more extruder screws is established on the basis of a mathematical model,
wherein the changing of the rotational speed of the one or more extruder screws is configured to occur when the one or more extruder screws are at a plurality of rotational angles, and
wherein the plurality of rotational angles are within a range, the range being determined using available measurement data on a composition pressure of the plastics composition.