Hot pressing process for medium density fiberboards

Abstract

The invention discloses a hot pressing process for medium density fiberboards. The hot pressing process comprises feeding, a first hot pressing stage, a second hot pressing stage, a third hot pressing stage and discharging. The hot pressing process is reasonable; by effectively controlling pressurizing time, pressure releasing time and pressure maintaining time of a hot press, the hot pressing time is shortened by 30-50 seconds compared with the time in the traditional hot pressing process, and the internal bond strength of slabs is improved by 20-30 percent; moreover, performance indexes of boards are strictly controlled, so that the thickness of the hot-pressed slabs is more accurate, the thickness of solidified layers of the boards after solidification is 0.3-0.8mm, and the manufacturing cost is reduced to the greatest degree; meanwhile, the problem of negative influence of steam pressure in core layers of the slabs on the performance of the boards is avoided, the stability of product quality is improved, the rejection rate of products is greatly reduced, and the production efficiency is improved; the method is also suitable for the hot pressing process for medium density fiberboards in different thicknesses, and is easily promoted on a large scale.

Description

technical field [0001] The invention belongs to the technical field of wood-based panel manufacturing, and in particular relates to a hot-pressing process for medium-density fiberboards. Background technique [0002] MDF is a product widely used in furniture manufacturing, upholstery, construction, packaging, home appliances and other industries. The production line of medium density fiberboard is divided into slicing section, hot grinding section and hot pressing stage, and the hot pressing process is an important process in the production of medium density fiberboard. The fiberboard is compressed to a specified thickness, and through the contact heating of the pressing plate, a series of physical and chemical changes will occur between the wooden structural unit and the adhesive in the slab, and the adhesive will be cured to form a specified physical and mechanical structure. MDF. The traditional hot pressing process is usually that after the slab is loaded, the hot pres...

AI Technical Summary

Problems solved by technology

The traditional hot pressing process is usually that after the slab is loaded, the hot press is quickly closed to the final position, and the hot press is turned on after holding the pressure for a period of time to complete the hot pressing process. In the above hot pressing process, after the slab is heated, the slab The vaporization of the steam on the surface of the billet is easy to transfer a large amount of heat from the core layer, causing a large amount of heat to accumulate inside the core layer, resulting in a large vapor pressure, and the generated vapor pressure is difficult to discharge from the core layer, which is easy to affect the performance of the board. Influenced, resulting in large differences in the performance of the produced slabs, and the traditional hot-pressing process only controls the pressure of the hot-pressing, but ignores the time of pressurization, pressure release, and pressure-holding of the hot-press machine and the thickness of the slab The control of hot pressing not only results in long hot pressing time and low working efficiency of hot pressing, but also blinds the technological parameters of the slab thickness for a long time, which easily makes the density of the slab too high, consumes a lot of raw materials, and consumes adhesives. The quantity is large, the manufacturing cost is high, the cured layer is too thick, and the waste rate of the slab after hot pressing is 10-20%. It can be seen that the index control of raw materials in the hot pressing process, the pressure, temperature, and time of hot pressing is a key factor affecting product quality