1. Open threading

The transfer from the wire section to the press section generally uses an open-type paper transfer for low- and medium-speed Fourdrinier paper machines. The method is to use the water needle of the wire section to cut the wet paper sheet that enters the flat roller to make it into a narrow strip of 50-100 mm; for the low-speed paper machine using ordinary flat rollers, manual drawing machines are generally used. The narrow strips of paper passing through the veneer roll are glued up with a mass of semi-dry slurry and led to a pressing felt. For the paper machine using the vacuum veneer roll, the compressed air installed in the vacuum veneer roll can be used. The nozzle blows up the wet paper sheet at a pressure of 4-6 atmospheres and sends it to a pressing felt.

2. Sticky paper

Sticky threading paper is suitable for medium speed and low basis weight paper machines. The paper threading method is to paste the wet paper on the volt-roller under the paper threading blanket for great delivery. It relies on the adhesion of a thin layer of water film on the surface of the blanket and the weak suction effect of rotation. Therefore, the requirements: the carpet has strong tissue, tight weaving, smooth surface and singeing. Needle-punched blankets are now used, and the blankets (especially the two sides) must be cleaned during operation.

The advantage is that the paper threading structure is simple, the paper net marks are lighter, and the paper threading felt has a long life.

Disadvantages: sticking and drawing paper requires a large amount of paper drawing felt. In order to avoid embossing, the paper pressure of the pressing roller is low, and the dehydration efficiency is not high. It is only suitable for paper machines for making thin paper, and the basis weight should not be too high. Because the paper threading blanket is dense, it is difficult to transfer the wet paper to a pressed blanket, and it is generally used for the cylinder paper machine or the Fourdrinier single cylinder paper machine that produces thin paper.

3. Vacuum threading

Due to the high speed of the high-speed paper machine, the open paper delivery is difficult. Therefore, most of the paper delivery from the wire section to the press section uses a closed paper delivery method, that is, a vacuum paper threading device is used to deliver the paper. In order to facilitate paper threading, After the forming wire passes through the vacuum roll, there is a straight section with an inclination angle of about 45°. Here, the wet paper sheet is sucked away from the forming wire by the vacuum drawing roll by the combined action of the vacuum and the capillary tube and attached to the thread felt. Then, the wet paper is transferred to the first press felt through the paper transfer press, and then enters the second press (the paper transfer press and the first press share the same blanket).

The position of the vacuum guide roller can be located between the vacuum flat roller and the driving roller, or near the driving roller. The structure of the vacuum paper roll is similar to that of the vacuum press roll. When starting the paper threading, the vacuum paper threading roller is gradually lowered to contact with the forming wire, and the paper threading vacuum degree is generally 300~400mmHg.