Views:6 Author:Site Editor Publish Time: 2020-06-15 Origin:Site
In the manufacture of plywood, the moisture content of the veneer after rotary cutting is very high. If the veneer is directly glued without drying, the time of hot pressing will increase during the hot pressing process, and the plywood produced is also prone to bulging. Can not even glue, reduce our production efficiency. In addition to affecting the manufacturing quality of plywood, wet veneers are prone to mold during storage, and cracks or warps are easy to occur at the edges, so wet veneers are not suitable for storage. Therefore, in the production of plywood, in order to ensure the quality of the product, the veneer after rotation must be dried.
The quality of the veneer directly affects the quality of the plywood, and the processing of the veneer is a very important link. The processing of veneer mainly includes the veneer rotary cutting, veneer drying, veneer glue fight and so on.
Let's talk about the drying of the veneer first. There are two types of veneer drying: natural drying and machine drying. Natural drying is to place the veneer in an open space, using air convection and sun light to evaporate the moisture of the veneer to achieve the purpose of drying. However, the efficiency of natural drying is low, the labor intensity is also large, and the quality of drying is relatively poor, and it is easily deformed, and the moisture content can only reach the equilibrium moisture content. In addition, natural drying is greatly affected by weather and seasons, and is not suitable for large enterprises.
Machine drying is the use of drying equipment (veneer dryer) to dry the veneer. The veneer dried by the veneer dryer has high efficiency and good veneer quality. Generally, plywood manufacturers use various types of dryers to dry the veneer.
There are many types of veneer dryers, which can be divided into air convection veneer dryer machine, contact veneer dryer machine and combined veneer dryer machine according to the heat transfer method.
In the air convection veneer dryer, the circulating hot air transfers heat to the single board.
The contact veneer dryer is a direct contact between the hot steel plate and the veneer to transfer the heat to the veneer.
The combined veneer dryer is a combination of convection heat transfer and other forms of heat transfer to transfer heat to the veneer.
According to the transmission method of the veneer, it is divided into a mesh belt veneer dryer machine and a roller veneer dryer machine.
The mesh belt veneer dryer places the veneer between two layers of steel mesh for transportation, and dries the veneer through the dryer.
In the roller veneer dryer, the veneer is sandwiched and conveyed by the upper and lower rollers, and dried by the dryer.
According to the relationship between the circulation direction of hot air in the dryer and the longitudinal centerline of the dryer, it can be divided into a longitudinally ventilated veneer dryer machine and a laterally ventilated veneer dryer machine.
The longitudinal ventilation veneer dryer machine circulates hot air along the length of the dryer. The airflow and the conveying direction of the veneer are the same, called forward; the airflow is opposite to the conveying direction of the veneer, called reverse. The hot air circulation system of the longitudinal ventilation dryer is relatively simple, and the drying effect of the veneer is relatively poor.
The horizontal ventilation veneer dryer circulates hot air along the width of the dryer. The airflow is parallel to the surface of the veneer or perpendicular to the surface of the veneer. The drying effect of the veneer is better.
In the production of plywood, you can choose according to your production requirements. Choosing the right veneer dryer can improve the production efficiency of plywood.