Process and machine for the manufacture of a paper web that is smooth on one side

Abstract

A method to manufacture a fibrous web in the form of a paper web, which is smooth on one side, by a papermaking machine having a forming area, a pressing area and a drying area. The method including picking up the paper web from the forming area by a water absorbent first press felt; guiding the paper web together with the first press felt and a smooth transfer belt through a first press nip. The smooth transfer belt being configured to substantially not absorb any water. The first press nip being a part of the pressing area. The first press felt being configured to be separated and led away from the paper web immediately after the first press nip. The method further including the steps of leading the paper web together with the smooth transfer belt away from the first press nip; and subsequently leading the paper web from the smooth transfer belt by way of a conditioned water absorbent second press felt, the second press felt not passing through the first press nip; and subsequently guiding the paper web together with the second press felt through a second press nip, the second press nip being associated with the drying area.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of PCT application No. PCT / EP2008 / 056757, entitled “METHOD AND MACHINE FOR PRODUCING A PAPER WEB THAT IS SMOOTH ON ONE SIDE”, filed Jun. 2, 2008, which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention pertains to a process as well as a machine for the manufacture of a paper web of paper that is smooth on one side.[0004]2. Description of the Related Art[0005]The production of paper, that is smooth on one side, and which has a basis weight (gsm=grams per square meter or g / m2) of conventionally 20 g / m2 up to 80 g / m2, or in particular 16 g / m2 up to 40 g / m2, is nowadays mostly conducted with so called MG-machines (MG=machine smoothened or flattened). The web, which has a comparatively low dry content, is transferred by the use of a pressure roller onto the smoothing cylinder or Yankee cylinder, respectively. The production output of such a machine is limite...

AI Technical Summary

Benefits of technology

[0010]The basic objective of the present invention is to provide a better method as well as an improved machine, which is not disadvantaged by the before mentioned issues. The present invention provides an efficient, mechanical drainage for the web before the thermal drying is initiated inside the drying area, and provides a contained guidance of the web to prevent it from breaking, from the forming area up to the drying area, and in particular, to the smoothing cylinder or Yankee cylinder both of which are associated with the drying area.

[0012]The more efficient mechanical drainage of the web, which takes place before the thermal drying is initiated inside of the drying area, brings on a noticeable increase in production capacity. In addition the method provides a contained guidance of the web and prevents it from breaking from inside of the forming area or the screen, respectively, up to the smoothing cylinder or Yankee cylinder, located in the drying area.

[0014]It is of further advantage if the first press nip, which is associated with the press area, is in the form of a shoe press.

[0021]It is of further advantage if the smooth side of the paper web, which previously faced the smooth transfer belt, would be passed with its smooth side facing the smoothing cylinder or the Yankee cylinder.

Problems solved by technology

The production output of such a machine is limited though by the evaporative capacity of the cylinder and the hood associated with it.

The presses are, in this instance, covered with felt on both sides of the web, which is why the attainable dry content is limited by remoistening.

In this case the light weighted web can be remoistened, which is quite undesirable.

Following a method and a machine, both of the initially described kind, and known from DT 24 43 099 A1, a web of paper, which is being processed, runs after the first press nip onto a felt, which can cause remoistening of the web, which is undesirable.

It is a further disadvantage that the press area does not contain a covering to provide a support for the web.

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