In the production of plywood, the pressure uniformity of the hot pressing equipment is a key factor affecting the quality of the finished product. If the pressure distribution is uneven, it may cause local delamination, bubbling, or thickness deviation of the board, directly affecting the mechanical properties and appearance quality of the product. Therefore, optimizing pressure control technology is one of the core tasks of plywood factories.
To ensure pressure uniformity, it is necessary to start from two aspects: equipment structure and operation process. The hot press machine needs to be equipped with a high-precision pressure sensor grid system to monitor the pressure in various areas in real time, and dynamically adjust the output pressure through the hydraulic system. For example, in the production of twelve layer boards, the pressure difference needs to be controlled within 3% to avoid local "mirror effect" or wavy deformation. In terms of equipment maintenance, it is necessary to check the parallelism of the hot press plate every month. If the error exceeds 0.1 millimeters, it should be ground and corrected in a timely manner. At the same time, the hydraulic oil filter should be cleaned regularly to prevent impurities from blocking and causing pressure fluctuations.
In the operation process, pressure parameters need to be adjusted according to the number of layers of the board, tree species characteristics, and environmental humidity. For example, when pressing seven layers of pine boards, the pressure should be controlled at 7-8 megapascals; And hardwood veneers such as birch need to be raised to 9-10 megapascals. During rainy season production, if the moisture content of the veneer exceeds 12%, an additional compensation pressure of 0.3 megapascals is required. In addition, adopting a segmented pressure strategy can improve the quality of bonding: in the initial stage, low-pressure infiltration glue is used, in the middle stage, pressure is increased to discharge bubbles, and in the later stage, pressure is maintained to ensure complete curing.
Through equipment upgrades and process optimization, plywood factories can significantly improve the uniformity of hot pressing pressure, thereby ensuring product stability and market competitiveness.
