Views: 1 Author: Site Editor Publish Time: 2022-04-12 Origin: Site
Development situation and development trend of headbox
The earliest used headbox was the open ram headbox, which was produced before the Fourdrinier brothers invented the Fourdrinier paper machine in 1804. Its structure and form are relatively simple, the technical requirements are not high, it can only be applied to low-speed paper machines, and the homogenization effect is poor.
As the speed of the paper machine increases, the static head required for the formation of the paper stock in the weir must increase with the square relationship of the speed, so when the speed of the paper machine increases, the required static head must increase. At higher vehicle speeds, if an open headbox is used, it becomes large and complex in terms of volume, height, structure, and weight. Moreover, it is impossible to efficiently disperse, straighten and disperse fibers in such a large volume of paper stock in the weir pond to provide a high-quality web-jet paper stream. To solve this problem, closed (air cushion) headboxes were researched and developed in the late 1940s.
After the 1970s, the developed air-cushion headbox absorbed the advantages of some headbox designs, and adopted some new headbox technologies such as conical distribution headers, hydraulic distribution rectifiers, elimination of foam overflow, optimization of upper and lower headboxes. The lip structure, etc., has been greatly improved in performance, so it is also widely used in medium-speed Fourdrinier wire paper machines and sandwich wire paper machines.
Since the 1970s, in order to meet the needs of the development of new multi-layer forming technology, a multi-layer hydraulic headbox has been researched and developed. Multi-layer hydraulic headbox is a multi-channel full flow hydraulic headbox. At present, the multi-layer hydraulic headbox can be used not only for the production of cardboard, but also for the production of tissue paper and high-grade paper. It plays a good role in improving the quality of paper and rationally using fiber raw materials. Headbox has a very good development prospect. At present, multi-layer hydraulic headboxes with various structures have been researched and developed.
Since the 1990s, the research and development of the control and adjustment technology of the dilution water concentration in the headbox has been a major achievement and progress in the common technology of the headbox. The headbox adopts the dilution water concentration control and adjustment technology to adjust the bias flow and cross flow caused by the weir plate. Several systems have been developed, and most new headbox designs use this technology.