The headbox is known as the "heart" of the paper machine. It is a key component of the paper machine, a hub connecting the "flow conveying" and "forming" parts, and one of the fastest growing parts of the paper machine. In papermaking, the function of the headbox is to deliver the pulp that meets the requirements to the forming wire according to the requirements of the forming part of the paper machine, providing the necessary premise for the good forming of the paper web.
The Function of Headbox
As the junction of the "flow" and "forming" of the papermaking machine, the basic task of the headbox is to provide good prerequisites for paper sheet forming, that is, to evenly distribute the paper material along the width of the papermaking machine, to ensure uniform pressure, speed, flow, concentration, and controllability and uniformity of fiber orientation; to effectively disperse the pulp fibers and prevent fiber flocculation, and to provide and maintain a stable sizing pressure head and pulp-to-net speed ratio according to process requirements.
The structure of Headbox
In fact, the functions of any type of headbox are specifically undertaken and coordinated by three major parts: the pulp distributor, the rectifier, and the paper stock screen device. The functions of these three major parts are as follows:
Pulp distributor:According to the principle of fluid dynamics, the paper stock flow on the screen is evenly distributed along the width direction of the paper machine with a certain pressure, speed, and flow rate using a regular variable cross-section.
Rectifier:Use the rectifier element and turbulence generator to generate turbulence of appropriate scale and intensity, effectively disperse the fibers, prevent fiber flocculation, and keep the fibers in the non-directional arrangement as much as possible, so that the fibers in the paper stock flow on the screen are in a uniformly dispersed state.
Paper stock screen device:Make the paper stock spray evenly, at a certain angle and spraying speed, to the predetermined screen point on the screen, and provide the quantitative and fine adjustment of the water content in the width direction of the paper machine, and the control and adjustment of the turbulence and flocculation scale of the pulp flow to ensure the required quality of paper sheets.
Open Type Headbox
The open headbox is suitable for vehicle speeds below 200m/min. The configuration of the headbox slurry flow channel, homogenizing roller, etc. is basically the same as that of the air cushion type. Its spraying speed is adjusted by adjusting the slurry height by using the gate plate and changing the spraying pressure. The box is equipped with a spray pipe, which can automatically clean the inner surface, eliminate bubbles, stabilize the slurry surface, and achieve smooth sizing.
Hydraulic Type Headbox
The hydraulic headbox is suitable for the speed range of 500-1200M/MIN. The pulp is evenly distributed along the width of the paper machine through the conical pulp distribution main pipe and the stepped tube bundle. Dilution water is injected into the pulp flow before the pulp enters the stepped tube bundle to adjust the pulp flow concentration, realize the local fine adjustment of the horizontal quantitative of the paper, and improve the quantitative of the entire paper industry.
Air Cushion Type Headbox
The air cushion headbox is suitable for a speed of 200-500m/min. The slurry is fed from a square cone tube, evenly distributed into the box through a stepped diffuser, and rectified by two homogenizing rollers. A spray pipe is installed above the box, and an overflow device is configured to prevent bubbles from being brought onto the table. Then it enters the convergence channel where the upper lip plate can be adjusted in the vertical and horizontal directions, and finally sizing is achieved.
Sun Hong Group
Sun Hong Group is a comprehensive company integrating planning, design, technical support, production, testing and training. We have a professional technical team to provide you with professional design and technical support as well as the best source of goods. After more than ten years of efforts, our products have been exported to 96 countries, and have more than 300 paper plants customers. Sun Hong Group have a wide range of business, we can design and produce various customized products according to the different requirements of different customers. Mainly involving Paper Machine Clothing, Industrial Fabric, Paper and pulp machine spare parts, test equipment, etc. In addition, we also provide customers with update and transformation services to enhance customer output.
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