De-watering drum for manufacture of paper, carton or tissue paper has first array of large diameter holes linked by secondary array of smaller diameter holes

摘要

A paper manufacturing assembly has a se-watering drum with a regular array of numerous water drain holes of a first diameter, separated by a second array of drain holes of smaller diameter. The smaller drain holes interrupt the surface material between the larger array of drain holes. The location of the secondary array of holes is chosen such that the residual bridge-pieces facilitate operation without a sieve jacket. The large and small holes have a small degree of overlap. The secondary holes are located at the centre of gravity of a triangle defined by three adjacent apertures (2). Also claimed is a drum manufacturing process in which the grooves are formed by a stamp or die, followed by de-burring, sand blasting and coating with an anti-wear compound.