Headbox is known as the “heart” of the paper making machine, is a key part of the paper making machine. It is a hub connecting the two parts of “flowing” and “forming”, and is one of the fastest growing parts on the paper making machine. The function of the headbox in paper making is to send the required pulp to the forming screen according to the requirements of the forming part of the paper making machine, providing necessary prerequisites for good forming of the paper web.

Function and performance of headbox

As the combination part of “flowing” and “forming” of the paper making machine, the basic function of the headbox is to provide good prerequisites for paper formation, that is, to distribute the paper evenly along the width of the paper making machine to ensure uniform pressure distribution, speed ​​uniformity, flowing uniformity, concentration uniformity, and controllability and uniformity of fiber orientation; to effectively disperse pulp fibers, prevent fiber flocculation and provide and maintain stable sizing head and pulp speed ratio according to process requirements.

In the long-term development of pulp and paper technology, although various structural forms of headboxes have appeared, their main functions remain the same basically, that is, cloth distribution, homogenization and spraying. The basic functions of the headboxes are expressed in five aspects specifically:

  1. Provide a uniform and stable blown pulp flow to the entire width of the paper making machine, avoiding lateral pulp flow and having no directional transverse flow or longitudinal flow.
  2. Provide a stable lip with a satisfactory geometric size, which is not affected by temperature, pressure and lip opening.
  3. Form a fiber suspension with minimum flocculation and good dispersion.
  4. Provide the controls of the quantitative distribution of the web, the pulp falling point, the pulp blowing angle and speed that can meet the process requirements.
  5. Provide convenient measures to keep the headbox clean and easy to operate and maintain.

A good headbox must have the following proformances:

  1. It can produce a uniform and stable paper web with no quantitative longitudinal flow on the paper web.
  2. The lip area of ​​the headbox should not be affected by pressure, temperature and opening to ensure uniform distribution.
  3. The phenomenon of pulp hanging and pulp attachment should be avoided in the headbox.
  4. It is easy to keep it clean.
  5. It can Control pulp-screen speed ratio.

Therefore, the headbox must:

  1. Be evenly distributed in the direction of the paper making machine.
  2. The blown pulp has a uniform velocity profile, concentration profile and turbulence profile.
paper headbox


In general, the function of the headbox is to blow the uniform pulp flow on the screen of the paper making machine at a certain angle along the width direction to under uniform pressure, speed and flow required by the paper making process and the internal fibers as much as possible. At the same time, the width of the paper making machine and the fine adjustment of moisture are provided to ensure that the required quality paper.

In fact, the any type of headbox is specifically carried out and coordinated by the three main parts of the pulp distributor, rectifier and material charging device. The functions of these three parts are:

Pulp distributor: According to the principle of fluid dynamics, it can use a regular variable cross-section, the paper flow is uniformly distributed along the width direction of the paper making machine at a certain pressure, speed and flow rate.

Rectifier: It can use the rectifier and turbulence generator to generate turbulence with appropriate size and strength, effectively disperse the fibers, prevent the flocculation of the fibers, and maintain the non-directional arrangement of the fibers as much as possible, so that the fibers in the paper flow are in a uniformly dispersed state.

Material charging device: It can make the paper material are blown uniformly at a certain angle and speed to the predetermined screen points, and provide the quantitative of the width of the paper making machine, make fine adjustment of moisture content, the turbulence of pulp flow, and the scale of flocculation control to ensure that we can get the paper with the required quality.

As a leading paper making equipment manufacturer, AGICO can provide you with high quality paper making machine and relevant information about headbox in details.

Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fiber crops, waste paper, or rags. Many kinds of paper are made from wood with nothing else mixed into them. This includes newspapers, magazines and even toilet paper. Pulp is one of the most abundant raw materials.

A pulp mill is a manufacturing facility that converts wood chips or other plant fibre source into a thick fibre board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical or fully chemical methods (kraft and sulfite processes). The finished product may be either bleached or non-bleached, depending on the customer requirements.

A paper machine (or paper-making machine) is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.

The pulp produced up to this point in the process can be bleached to produce a white paper product. The chemicals used to bleach pulp have been a source of environmental concern, and recently the pulp industry has been using alternatives to chlorine, such as chlorine dioxide, oxygen, ozone and hydrogen peroxide.

Chemical pulp is produced by combining wood chips and chemicals in large vessels called digesters. There, heat and chemicals break down lignin, which binds cellulose fibres together, without seriously degrading the cellulose fibres. Chemical pulp is used for materials that need to be stronger or combined with mechanical pulps to give a product different characteristics. The kraft process is the dominant chemical pulping method, with the sulfite process second. Historically soda pulping was the first successful chemical pulping method.