The function and classification of the net cage of the cylinder paper machine

The cage is the main component on which the paper web is formed in the cylinder paper machine. It is required to filter water evenly and not produce excessive agitation in the mesh tank when rotating. The cage should have sufficient rigidity and accurate geometric dimensions, and should be installed horizontally.

According to the structure, the round net cage is divided into: ordinary, sheet type, suction, and vacuum net cage; according to the material, it is divided into: ordinary, all-copper, and stainless steel net cage.

A brass supporting rib device called a spoke is installed on the cast iron shaft, and the distance between the spokes is 100-150mm. The spokes support the center rim, and the periphery of the spokes is carved with grooves. The grooves are equipped with horizontal bars with the same length as the net cage. The horizontal bars are about 1cm in diameter, with a center distance of about 4cm, and are parallel to the center axis. The horizontal bar is made of steel or brass, and its cross-section can be round or rectangular. The rims on the outermost two sides are cast with protruding rims to form a seal with the corresponding parts of the mesh groove to isolate the inside and outside of the mesh cage. A zigzag-shaped groove is milled on the horizontal bar according to the spiral line, and a continuous metal wire with a diameter of about 3mm is spirally wound on the round net cage to form a cage-like net cage frame. The gap between adjacent metal wires is about 1 cm. Finally, the copper wire is covered with a thicker brass or stainless steel inner net, and then a thinner surface net for papermaking. The inner net and the surface net are both nets with ends, which are tightened on the net cage frame with special tools and connected by silver welding or electric welding. The final assembly must be very round and concentric with the central axis, and its rigidity must be sufficient to withstand the pressure of the roller without deformation. The diameter of the standard cage is about 1-1.5m, and the common size is 1.2m.

The cage bearing of the paper machine is installed outside the cage. The two ends of the net cage communicate with the side boxes of the net trough. After the slurry goes online, the white water filtered into the mesh cage through the copper mesh enters the side box from both ends of the mesh cage, and then is pumped out by the white water pump for recycling.

In addition, some paper mills use mesh cages made of high-quality wood (soak-resistant and less deformable). There are also some net cage structures without the spoke support, which is a completely hollow net cage.

The inner net of the net cage generally uses 8-16 mesh, which is mainly used to disperse the pressure of the roller and keep the surface net flat. The surface net is relatively dense, used to filter fibers to form a paper web, generally 40-100 mesh. The selection of the mesh is mainly determined by the type of paper produced. The most commonly used mesh for the production of general cultural paper is 65 mesh.

The sheet-type net cage of the paper machine is to change the outer circle of the ordinary net cage to a rectangular section stainless steel plate with a φ3mm cross-section copper wire. Its main features are: increase the filtration area and speed, increase the output; improve the quality of the finished paper, including uniformity, basis weight, aspect ratio, reduce the consumption and maintenance costs of copper mesh, blankets, etc.; strengthen the integrity and anti-corrosion performance of the equipment, High strength, good rigidity and durability. The sheet net cage has been developed and produced with three kinds of sheet nets: through sheet, winding sheet and oblique sheet.