Paper machine

The paper machine is a machine for the production of paper, cardboard or paperboard.

Fourdrinier

The Fourdrinier machine was invented in 1798 by Frenchman Nicholas -Louis Robert ( patent on January 18, 1799). Has on the principle of its paper machine since then nothing has changed. A fiber suspension is applied over a bucket and a headbox onto a vibrating screen, the screens and drained (now with suction cups ). The crude dewatered but still wet paper is then passed through press rolls, and through the now provided with the steam-heated drying cylinders, the drying section further dried.

The power of today's paper machines is certainly greater by a multiple. To produce a modern paper machine in one hour more than the annual production of a paper machine of the 19th century. The dimensions are currently at about 12 m working width and a total length of about 100 m, the total height extends to over 2 floors. The production speed is 1800 m / min for ( newsprint, tissue paper ). Faster plants are already in the immediate introduction phase. Currently encounter modern paper machines up to 2000 m / min, not just short-fiber newsprint, but mainly test liner.

Other design principles

Other forms of construction are the cylinder mold of the Englishman John Dickinson ( as the inventor / designer of the first RSPM shall the Briton Joseph Bramah, first published 1805) and in 1881 by Max Sembritzki, director of the Austrian paper mill Schlöglmühl (district Neunkirchen ), invented arc pumping machine. Furthermore, there were several attempts to develop arc scooping machines that were suitable to mimic the process of scooping hand - but without success.

The construction of a paper machine depends on the type of paper to be produced from each and can be very different accordingly. Basically, the operating principles wire, cylinder mold, combined must ( Fourdrinier and cylinder mold together), Screen Opener and grouping within the machine in sheet forming zone, press zone and drying zone are observed.

Within the subgroups, there are again distinctive ways that are specific to the technology of sheet formation ( vibrating, inclined, Duoformer, Gegenstrom-/Gleichstromprinzip ... ), the press ( press rolls, suction press, shoe press ... ) or to the type of transfer and drying ( Yankee machine, through-air ... ) refer.

The oldest operating principle is the Fourdrinier machine with horizontal wire run, dewatering rolls / foils, suction boxes and a Gautsche. The drying section is initially recognized by Bryan Donkin and Henry Fourdrinier on a paper machine. For a long time therefore it is called the Fourdrinier machine with steam-heated drying section also " Fourdrinier machine".

Besides the classic Fourdrinier machine having a headbox and Siebentwässerung also paper machines with Jetformern ( siebfreie machine ) or anhydrous sheet formers are currently being operated by the electrostatic principle.

Machines for the manufacture of security paper ( paper money, equity securities ) often represent a combination of different basic designs dar.

Sections of a paper machine

Constant part

The term constant part of all plant parts between mixing or machine chest and headbox of the paper machine are summarized. The constant part is used to connect the stock preparation to the headbox of the paper machine. The stock suspension is diluted in this area to the required consistency. The fuel density in this range is between about 0.03 and 1.5%. Since in this consistency area easy removal of impurities is possible, the flow system is usually equipped with an LC screening.

Wire section

The wire section of a Fourdrinier paper machine consists of the headbox, various drainage elements such as String strips and vacuum suction and optionally a dandy roll or hybrid former. After dilution and order of the pulp suspension in the constant part, the sheet-forming part of the suspension ( the wire section ) must now be uniformly supplied to the paper web width. This is the task of the headbox. The dewatering elements are used to remove the water suspension. The dandy roll or hybrid former is responsible for the production of a uniform fine texture surface. After the wire section there is a solids content of up to 24%.

Press section

In the press section, the wet fibrous web is couched from a decrease in suction ( suction roll or static negative pressure producing member ) onto the press felt. The function of the press felt is to transport the fibrous web through the press nip of various modifications. The dry content of the web after the press section is up to 55%. In the press nips, the paper web can even reach a dry content of about 70%. However, the web is rewetted by the capillary action. The press section is the last section, is dewatered mechanically with.

Drying section

The drying section is responsible for achieving the Endfeuchtegehaltes the paper web. This is at equilibrium with the ambient air ( about 4-6 % of paper and cardboard and 8 to 12 %). Usually it involves a thermal drying using steam-heated drying cylinders. In the dryer section is still also possibly a glue or film press or other processing units for imparting water repellency of the paper web surface. However, these components can also be used according to the machine that is offline. In general, the drying section is completed with a water-cooled roller pair to bring the heated paper to return to room temperature.

Reeling

In Aufrollungsbereich the paper machine to rewind the paper web is on a so-called drum. The weight of the drum ranges from 3 tons to 150 tons. The base paper is now ready for further processing, eg in the calender or for the stroke order.

Equipment

• Slitter

In Slitter ( Winder ) of the drum is inserted and cut by blade at up to 3,000 m / min into smaller rolls and possibly rotated internally and externally. Types are the support and the drum winder.

• Sheeter

Sheeter cut the drum (optional roles from the rewinder ) to predefined formats. They are even having a cross section diameter (simplex ) is only one format can cut at once, and with two cutting portions ( duplex) in which you can cut simultaneously 2 different formats. The maximum speed is 2200 m / min

Quality assurance

In the paper machine several measurement framework can be (at least one before the reel ) installed. These cover over the entire web width different values ​​, which are defined depending on the type of paper. These values ​​are grammage, moisture, thickness, track width, opacity, smoothness, whiteness, shading and density or specific volume. For further quality assurance samples are taken and tested from each finished reel.