Twin wire formers

Twin-wire formers providing more symmetrical z-structure of the paper and high machine speeds... 

Eckl, DuoFormer TQv - a new twin wire former, twogether-Paper Technol. J. Voith Pa- H. per 2000, 10, 17. 

Making paper by a eontinuous proeess dates back to 1798, with Robert s invention of the foremnner of the modem Fourdrinier former. Many different types of formers are in use today. They are of three basic types, the Fourdrinier former, the twin wire former, and the cylinder former. Eaeh has many variations on the basic design, and is especially suited to partieular papers. Fourdrinier and twin wire formers are used to make papers that range from extremely lightweight tissue grades to linerboard. Cylinder maehines are used to make heavyweight papers and paperboards that are formed in several layers. 

The twin wire formers are a variaton of the Fourdrinier. The Fourdrinier tends to make a sheet that is two-sided, beeause drainage occurs in only one direetion. The sheet is imeven in distribution of fine fibers, dyes, and filler pigments. This can be especially undesirable in colored papers, since dyes have a greater affinity for the finer fibers and pigment particles. Because water drainage on the Fourdrinier eoneentrates these fines on the wire side of the sheet, the color of darkly dyed papers tends to be imeven with the bottom and top sides distinctly different. 

The twin wire former has two eontinuous wire belts running very close together with the stock in between. This eonfiguration allows for drainage in both directions, avoiding two sidedness. Twin wire configurations can also be used to make a multilayer paper wherein the two layers may be of the same or different stocks. This is used to make heavier weight paper such as linerboard. 

Twin-wire paper formers, 18 120 Twisted nematic LCDs, 15 113 characteristics of, 15 114 Twisted pair wire cable, 7 714 Twisted yarn, 11 178... 

Machine configuration Twin wire, gap former or multi-ply vat machines all have different requirements in terms of free drainage and retention. 

Hydrauhc headboxes enabhng higher machine speeds, higher throughputs and easy apphcation of twin wire gap formers... 

Twin wire hybrid former where a rotating second wire is mounted on top of the fourdrinier wire, dewatering part of the suspension through the top wire. 

Twin wire gap former, which is the state-of-the-art wire section in high speed web forming, mostly dewatering the suspension to both sides. 

In a twin wire gap former (Fig. 6.38F), the suspension from the beginning is led between two wires operating at the same speed, and is drained through one side, or mostly both sides. One of the driving forces in gap former dewatering is the... 

High machine speeds require a twin wire gap former to ensure high uniformity of the product and sufficient dewatering capacity. Twin wire gap formers are available in different configurations. One is shown in Fig. 6.82 which depicts a state-of-... 

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