Twin wire former for a paper machine

Claim 1

A twin-wire former for a paper machine, having a twin-wire forming zone comprising, in the following sequence of twin-wire run, (i) a downwardly curved forming zone confined to a sector of a first forming roll, (ii) said twin wire run comprising a lower wire loop unit and an upper wire loop unit guided by guide rolls, the lower and upper wires being arranged to both run over said first forming roll and define a forming gap thereat, into which a slice part of a headbox is arranged to feed a pulp suspension jet, (iii) a second forming roll situated after said first forming roll, being situated at a lower level than said first forming roll, and also arranged to curve the twin-wire run thereabout to become either (a) substantially horizontal, (b) slightly upwardly inclined, or (c) slightly downwardly inclined, and (iv) a third forming element fitted after said second forming roll, said third forming element being either (1) a forming shoe fitted inside the lower wire loop, mounted on the frame of the lower wire unit, and having a ribbed deck with a relatively large curved radius, or (2) a combination of deflectors situated in the upper wire loop and in the lower wire loop after which the twin-wire forming zone ends and wherein said first forming roll has a large diameter and said second forming roll has a diametet substantially smaller than the diameter of said first forming roll, said first forming roll is mounted on a frame of the lower wire unit and is located within the lower wire unit, magnitude of said sector of said first forming roll is less than about 90° , and said second forming roll has a sector for the curving of the twin-wire zone which is less than about 90°.