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The forudrinier paper machine wire part forming board after the headbox
1. The forming plate of the wire section of the Fourdrinier paper machine is composed of several slats with narrow gaps . The function of the forming board is to control the amount of dewatering of the paper on the paper web, and to support the net between the breast roll and the first roll (or the first set of boards) to eliminate the phenomenon of pulp jumping and improve the paper sheet evenness.
2. The role of forming plate:
2.1 Controlling dewatering: A large amount of dewatering immediately after the pulp is put on the web is extremely detrimental to the formation of the paper web. It will cause the fibers to stand up and affect the strength of the paper; it will cause a large number of fine fibers to leak, cause different properties on both sides of the paper, and make the initially deposited fibers too tight, affecting the further formation and dehydration of the pulp;
2.2 Support forming net: It helps to eliminate the beating phenomenon when the slurry is initially on the net, and improves the forming of the paper sheet. If there is no forming plate, it will even cause the forming net to sag at the breast roll, resulting in pulp jumping on the screen.
3. Structure of forming plate:
3.1 Typical structure: The forming plates are generally long strips. Each forming plate is composed of 1-5 pieces. According to the requirements of the process, 1-3 pieces are configured. The first face is 100-200mm wide, and the rest is narrow, usually 65- 100mm with a pitch of 40-50mm.
3.2 Forming plates on modern paper machines: Usually, the meshing points of the box pulp surface, which is composed of a wide flat beam plate and several small inclination chopping boards, are on the plane near the leading edge of the beam plate. The slow dehydration can stabilize the pulp flow.
3.3 The material of the forming plate: It is required to be wear-resistant and have sufficient rigidity, the surface of the plate should be kept straight, and the leading edge of the slat should be neat and not warped. Nowadays, stainless steel structure is widely used, and the surface is inlaid with high-density polyethylene panel and ceramic. Ceramic panels sintered with alumina have good performance, wear resistance and smooth surface. Although the price is little expensive, they are more and more common used.
4. Use influencing factors:
4.1 Leading edge inclination: If the leading edge of the first slat is too square, water will be forced into the paper sheet, so the paper surface is rough. The edge thickness is 075-15mm. The rear slat faces the moving net at 60 °. Promote water to drain easily under the copper mesh.
4.2 Installation location:
The closer the first plate is to the breast roller, the smaller the amount of dehydration of the breast roller. If the slurry is sprayed on the mesh above the forming plate, the breast roller will not filter water, and a large amount of water will be taken away by the copper mesh to easily generate a longitudinal convex slurry flow on the free surface of the slurry (because The surface cannot be absolutely straight), and there is a danger of pulp passages when they collide with the adjacent pulp flow; on the contrary, if the slurry is sprayed on the copper wire near the front end of the board or the front edge, the paper sheet will be formed faster The pulp surface is flat, but the screen printing on the paper is heavier.
4.3 Installation angle and installation height: Properly lean forward, while leaving a certain gap with the net surface, you can control the amount of dehydration and reduce wear. Generally leave 15-3mm for the leading edge and 075-15mm for the trailing edge.
4.4 Adjustment device: The forming plate should be provided with an adjustment device in order to adjust the position, height and angle to meet the operation requirements.
Contact Person: Mr. Mark Zhang