Views: 2 Author: Site Editor Publish Time: 2022-02-26 Origin: Site
The breast roll is the first roll on the paper machine, and it is the beginning of the net form. One of its functions is to support the forming net. The forming wire changes direction on the breast roll, and after passing through the breast roll, the non-working surface of the forming wire becomes the working surface. In many cases, the breast roll is also a dewatering element on the wire case, and the pulp on the wire can shed some or most of the water on the breast roll.
The paper machine breast roll should have sufficient stiffness and minimum deflection to prevent the copper mesh from wrinkling. In order to reduce the load on the breast roller driven by the copper mesh, the weight of the breast roller should be light. Generally, the breast roll of small and medium-sized low-speed paper machines has no medium height, and the breast roll of large-scale high-speed paper machines is slightly medium-high.
In the past, the paper machine breast rolls were mostly made of copper, but now they are generally made of steel thin-walled tubes, covered with 3-4mm thick copper skin or 8mm thick rubber (Brinell hardness 12-17 degrees), and there are also breast rolls covered with glass fiber reinforced plastic. . Breast rolls are subject to static and dynamic balance inspections. In the paper machine, in order to prevent the fiber block from entering between the breast roll and the copper mesh, the roll surface is equipped with a plastic or wooden scraper to clean the roll surface, and a water spray pipe is also installed between the breast roll and the lower lip to clean the roll surface. Usually, there is an extension plate on the back of the scraper, where the white water removed by the mesh is led into the first white water tray.
The breast roll of the paper machine also has a dewatering effect, and its dewatering amount can be controlled by the landing point of the pulp flow. If the pulp flow falls directly on the breast roll, a large amount of water can be removed and there is a partial shaping effect. If the pulp stream is sprayed on the forming plate, the dewatering effect on the breast roll is very small, and the forming of the sheet is controlled by the table roll or dewatering plate. Modern high-speed paper machine for the production of tissue paper from free pulp, intensive dewatering with absorbent paper machine breast rolls. In this case, most of the water is removed by the paper machine breast roll.