Paper machine net forming ABC

　　The concept of the paper sheet forming between the two wires was proposed as early as 1875, but the prototype was officially made in 1953.

　　Daniel Webster is considered the inventor of the modern mesh former.

　　Parker once pointed out that only when the flow box is developed to provide a stable, uniformly dispersed fiber suspension for the paper machine, the advantages of the sandwich former can become a reality.

　　It was not until the reform of the flow box design that the mesh former was used in production.

　　For most interlock paper machines, since the dehydration is very rapid and there is almost no disturbance during the initial dehydration period, the quality of the paper produced by the interlock paper machine mainly depends on the uniform fiber distribution ability of the headbox.

　　Of course, it also depends on the dewatering element that is dominant in the forming zone.

　　According to the layout of the dewatering elements and the running track of the wet paper, the nets can be divided into horizontal nets, vertical nets, inclined nets and arc-shaped nets; according to the inner forming of the net, the dehydration elements can be divided into scraper nets. Maker, roll-type web former and roll-squeegee web former.

　　Representative of the most advanced high-speed web formers today are the Optifomer from Metso and Duoformer TQV from Voith.

　　Both types of formers belong to the roll-squeegee sandwich former.

　　With the increase of vehicle speed, both the roller type and the scraper type sandwich former have some shortcomings, for example, the uniformity gradually deteriorates.

　　Although the squeegee former obtains a satisfactory uniformity, the retention rate and the printing quality are not ideal. Thus produced a roll-squeegee structure of the sandwich former.

　　The forming dewatering element of the roll-scraper type sandwich former is mainly composed of a forming roll, a combined dewatering scraper, a loadable dewatering scraper, and a vacuum box vacuum roll.