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US-12618195-B2 - Press felt

US12618195B2US 12618195 B2US12618195 B2US 12618195B2US-12618195-B2

Abstract

A press felt ( 100 ) has a seam and a web-side and a machine-side. The press felt ( 100 ) has a first fiber layer ( 131 ) on the web-side, a second fiber layer ( 132 ) on the machine-side, and at least one woven base fabric ( 110 ) and at least one spiral fabric ( 120 ) between the fiber layers ( 131, 132 ).

Inventors

  • Viivi Villa-Nuottajärvi
  • Kati Mikkonen
  • Jorma NAAMANKA
  • Susanna Moisio
  • Juha Hynninen
  • Leena Silakoski

Assignees

  • VALMET TECHNOLOGIES, INC.

Dates

Publication Date
20260505
Application Date
20231121
Priority Date
20221124

Claims (18)

  1. 1 . A press felt having a seam and a web-side and a machine-side, the press felt comprising: a first fiber layer on the web-side; a second fiber layer on the machine-side; at least one woven base fabric and at least one spiral fabric between the fiber layers, wherein the at least one spiral fabric comprises: a plurality of spiral loop yarns, wherein adjacent spiral loop yarns form channels therebetween, the adjacent spiral loop yarns and channels positioned to extend around the press felt when it is installed in a paper machine, a cardboard machine, a tissue machine or a pulp machine; a plurality of pintle wires each extending through one of said channels, and thereby connecting adjacent spiral loop yarns; wherein the spiral loop yarns have loops exterior to the channels with free spaces inside the loops; and wherein filler yarns extend inside the free spaces to enhance entanglement with an adjacent one of the fiber layers, wherein the filler yarns are twisted yarns.
  2. 2 . The press felt of claim 1 , wherein the at least one spiral fabric is on the web-side of the at least one woven base fabric.
  3. 3 . The press felt of claim 1 , wherein the at least one spiral fabric is on the machine-side of the at least one woven base fabric.
  4. 4 . The press felt of claim 1 , wherein the first and second fiber layers are configured to extend through the at least one woven base fabric and the at least one spiral fabric, attaching the at least one woven base fabric and the at least one spiral fabric together.
  5. 5 . The press felt of claim 1 , wherein the at least one woven base fabric comprises machine direction yarns and cross machine direction yarns; and the at least one spiral fabric comprises spiral loop yarns and pintle wires.
  6. 6 . The press felt of claim 5 , wherein the pintle wires are arranged in a cross machine direction or angled to the cross machine direction in a plane of the spiral fabric.
  7. 7 . The press felt of claim 1 , wherein the seam is a double seam structure comprising a first seam in the at least one woven base fabric and a second seam in the at least one spiral fabric.
  8. 8 . The press felt of claim 7 , wherein the first seam is formed of woven fabric loops and the second seam is formed of spiral loops.
  9. 9 . The press felt of claim 1 , wherein the spiral loop yarns comprise a polymer.
  10. 10 . The press felt of claim 9 wherein the polymer comprising the spiral loop yarns is polyamide.
  11. 11 . The press felt of claim 10 , wherein the polyamide is selected from polyamide 4.6, polyamide 4.10, polyamide 5.6, polyamide 5.10, polyamide 6, polyamide 6.6, polyamide 6.10, polyamide 6.12, polyamide 10, polyamide 11, and polyamide 12, or mixtures thereof.
  12. 12 . The press felt of claim 1 , wherein cross-sections of the spiral loop yarns are round, oval, diamond, quadrangle or quadrangle with rounded edges.
  13. 13 . The press felt of claim 1 , wherein diameters of the spiral loop yarns are 0.1-3 mm.
  14. 14 . The press felt of claim 1 , wherein the diameters of the spiral loop yarns are 0.1-0.6 mm.
  15. 15 . The press felt of claim 1 , wherein loop sizes of the spiral loop yarns are 0.2-15 mm.
  16. 16 . The press felt of claim 1 wherein the loop sizes of the spiral loop yarns are 0.2-10 mm.
  17. 17 . The press felt of claim 16 wherein the loop sizes of the spiral loop yarns are 2-6 mm.
  18. 18 . A method comprising the steps of: positioning the press felt of claim 1 as a looped element within a paper machine, a cardboard machine, a tissue machine or a pulp machine; and advancing the looped element in a machine direction to receive fibers thereon for the formation of paper, carboard, tissue or pulp.

Description

CROSS REFERENCES TO RELATED APPLICATIONS This application claims priority on FI 20226049, filed Nov. 24, 2022, the disclosure of which is incorporated by reference herein. STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT Not applicable. BACKGROUND OF THE INVENTION The present invention relates to press felts used in fiber web machines. A press felt plays an important role in removing the water from a fiber web in a press section of fiber web machines. The press felt conveys the web through the press section and receives water removed from the web during pressing. At the same time, the press felt imparts smoothness of the web and conveys it to a dryer section. A modern press felt comprises at least one base fabric and a fiber layer at least on one surface of the base fabric. The base fabric can be a woven or non-woven fabric consisting of 1-4 layers. Conventionally used press felts have a low surface area, which enables producing of a web having a smooth surface. In other words, the conventionally used press felts have no marking effect. The marking effect means that the press felt produces uneven and structured surface on the web. There is thus a need for novel press felts having the marking effect. Further, the conventionally used press felts may have insufficient water removal properties due to the low surface area. Thus, there is also need for a novel press felt with an increased surface area for better evaporation of moisture from a pulp. SUMMARY OF THE INVENTION An object of at least some of the present embodiments is to provide a press felt having a marking effect and an increased surface area for better evaporation of moisture from a pulp. According to a first aspect of the present invention, there is provided a press felt having a seam and a web-side and a machine-side, the press felt having a first fiber layer on the web-side,a second fiber layer on the machine-side, andat least one woven base fabric and at least one spiral fabric between the fiber layers. According to a second aspect of the present invention, there is provided use of the present press felt in a fiber web machine, such as a paper machine, a cardboard machine, a tissue machine or a pulp machine. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspective view of a press felt in accordance with at least some embodiments of the present invention. FIG. 2 is a fragmentary side view of a spiral fabric in accordance with at least some embodiments of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present context, the term “spiral fabric” refers to a fabric comprising a plurality of spiral loop yarns and a plurality of pintle wires connecting the spiral yarns together. The spiral loop yarns interweave with adjacent spiral loop yarns like a zipper. The adjacent spiral loop yarns form a channel between the adjacent spiral loop yarns. The adjacent spiral loop yarns are connected with a pintle wire extending through the channel. There are free spaces inside loops of the spiral loop yarns, which free spaces can be filled with filler yarns. In the present context, the term “loop size” refers to a length (L) of a loop of the spiral loop yarn. The length is substantially perpendicularly or angled to a length direction of a pintle wire in a plane of a spiral fabric. In the present context, the term “web-side” refers to a side of a press felt, which side faces a fiber web, such as paper, board, pulp or tissue, produced, when the press felt is used in a fiber web machine, for example a paper, board, pulp or tissue machine. In the present context, the term “machine-side” refers to a side of the press felt, which side is in contact with equipment of the fiber web machine, when the press felt is used in the fiber web machine. In the present context, the term “machine direction” refers to a direction, which is parallel to the moving direction of the press felt in the fiber web machine, when the press felt is used in the fiber web machine. In the present context, the term “cross machine direction” refers to a direction, which is perpendicular to the moving direction of the press felt in the fiber web machine, when the press felt is used in the fiber web machine. A press felt plays an important role in forming of a surface and removing the water from a fiber web in a press section of a fiber web machine, such as a paper or a cardboard machine, or especially a pulp machine. At least some of the present embodiments provide a press felt having a marking effect, which can give an increased surface area for the fiber web for better evaporation of moisture from the fiber web in a drying section. According to an embodiment, a press felt 100 having a seam and a web-side and a machine-side comprises: a first fiber layer 131 on the web-side,a second fiber layer 132 on the machine-side, andat least one woven base fabric 110 and at least one spiral fabric 120 between the fiber layers 131, 132