阅读说明：本技术 一种高效保量单板干燥工艺方法 (Efficient and energy-saving veneer drying process method ) 是由 杨建雄 于 2019-10-09 设计创作，主要内容包括：本发明公开一种高效保量单板干燥工艺方法,在本发明中,工艺方法包括：预处理阶段；第一次干燥处理阶段；第二次干燥处理阶段；第三次干燥处理阶段；平衡干燥处理阶段；养生,将干燥完成的木材单板在室温下保持5天；对养生结束的木材单板进行含水量测定。通过本发明的工艺方法干燥的木材单板,在保证干燥质量,提高干燥速率的同时,能够有效降低干燥能耗。(The invention discloses a high-efficiency energy-saving veneer drying process method, which comprises the following steps: a pretreatment stage; a first drying treatment stage; a second drying treatment stage; a third drying treatment stage; a balancing and drying treatment stage; maintaining the dried wood veneer at room temperature for 5 days; and (5) measuring the water content of the wood veneer after the curing is finished. The wood veneer dried by the process method of the invention can effectively reduce drying energy consumption while ensuring drying quality and improving drying rate.)

1. A high-efficiency energy-saving veneer drying process method is characterized by comprising the following steps:

step S1, a preprocessing stage, namely performing rotary cutting and cutting on the log to obtain a wood veneer, and conveying the wood veneer into a first drying chamber through a conveying roller;

step S2, in the first drying treatment stage, after the wood veneer is conveyed into the first drying chamber, closing a door of the first drying chamber, raising the temperature in the first drying chamber to 60 ℃, keeping the humidity in the first drying chamber at 50% -55%, introducing hot air to the surface of the wood veneer, wherein the wind direction is vertical to the surface of the wood veneer, the wind speed is 15-20 m/S, after 30 minutes, stopping introducing the hot air, opening the door of the first drying chamber, and conveying the wood veneer subjected to the first drying treatment to a second drying chamber;

step S3, a second drying treatment stage, namely, after the wood veneer subjected to the first drying treatment is conveyed into a second drying chamber, closing a door of the second drying chamber, raising the temperature in the second drying chamber to 70 ℃, keeping the humidity in the second drying chamber at 40% -45%, introducing hot air to the surface of the wood veneer, wherein the wind direction is vertical to the surface of the wood veneer, the wind speed is 15-20 m/S, after 20 minutes, stopping introducing the hot air, opening the door of the second drying chamber, and conveying the wood veneer subjected to the second drying treatment to a third drying chamber;

step S4, a third drying treatment stage, namely, after conveying the wood veneer subjected to the second drying treatment into a third drying chamber, closing the third drying chamber and vacuumizing, keeping the vacuum degree of the third drying chamber between 0.01MPa and 0.05MPa, synchronously introducing pure nitrogen to replace gas in the third drying chamber, heating two hot pressing plates in the third drying chamber, controlling the heating temperature to be between 100 and 110 ℃, controlling the hot pressing plates to pressurize the upper surface and the lower surface of the wood veneer, controlling the pressure range of pressurization to be between 0.2MPa and 0.3MPa, and keeping the pressurization time to be 5 minutes; after the pressurization is stopped, conveying the wood veneer dried for the third time into a balance drying chamber; the hot pressing plate is in a grid shape, and the grid-shaped hollow area on the hot pressing plate accounts for 30% -70% of the whole area;

step S5, in the stage of balanced drying treatment, after the wood veneer subjected to the third drying treatment is conveyed into the balanced drying chamber, the door of the balanced drying chamber is closed, the temperature in the balanced drying chamber is increased to 75 ℃, the humidity in the balanced chamber is kept at 50% -55%, after 30 minutes, the door of the balanced drying chamber is opened, and the wood veneer is conveyed out of the balanced drying chamber;

step S6, preserving health, keeping the dried wood veneer at room temperature for 5 days;

step S7, measuring the moisture content of the wood veneer after curing; comparing the measured value with a standard threshold value, and if the measured value is greater than the standard threshold value, repeating step S4; and if the measured value is smaller than the standard threshold value, obtaining a qualified product.

2. The efficient and energy-saving veneer drying process method according to claim 1, wherein the specifications of the wood veneer are as follows: the length is 350 mm-450 mm, the width is 80mm, and the thickness is 2.0-2.5 mm.

3. The drying process of veneer with high efficiency and energy conservation as claimed in claim 1, wherein the specific determination method of step S7 is:

step S71, randomly extracting two wood veneers produced in the same batch;

step S72, respectively intercepting six samples with the length and the width of 20mm from the two extracted wood veneers;

step S73, measuring the weight m of the sample₁And recording;

step (ii) ofS74, putting the sample into an oven to be dried to be completely dry, and recording the weight m of the completely dry sample₀；

Step S75, calculating the water content of the sample; the water content formula is

Step S76, the calculated water content value W and the standard threshold value W₀Comparing; if the water content value W is larger than the standard threshold value W₀Then step S4 is repeated; if the water content value W is less than the standard threshold value W₀And obtaining qualified products.

Technical Field

The invention relates to the technical field of wood drying, in particular to a high-efficiency energy-saving veneer drying process method.

Background

Wood drying plays a significant role in wood processing. The drying of the veneer is a key process in the production process of plywood, solid wood composite floor base materials, container floors, artificial wood and the like. Veneer drying is also the most energy-consuming process in the production of plywood, solid wood composite floor substrates, container floors, manufactured wood and the like, and more than about half of the energy consumption is used for drying veneers in the production plant. Therefore, it is important for the manufacturing enterprises to improve the drying quality of the veneer, optimize the drying process of the veneer, and reduce the energy consumption of the production.

The medium temperature, medium humidity, air speed (air injection speed) and veneer thickness are all important factors influencing the veneer drying speed and drying quality.

Disclosure of Invention

In view of the defects in the prior art, the technical problem to be solved by the present invention is to provide a veneer drying process method with high efficiency and capacity retention, and the present invention aims to solve the problems of drying quality, drying rate, drying energy consumption, etc. of veneer drying.

In order to achieve the above object, the present invention provides a high-efficiency energy-saving veneer drying process, which is characterized in that the process comprises the following steps:

step S1, a preprocessing stage, namely performing rotary cutting and cutting on the log to obtain a wood veneer, and conveying the wood veneer into a first drying chamber through a conveying roller;

step S2, in the first drying treatment stage, after the wood veneer is conveyed into the first drying chamber, closing a door of the first drying chamber, raising the temperature in the first drying chamber to 60 ℃, keeping the humidity in the first drying chamber at 50% -55%, introducing hot air to the surface of the wood veneer, wherein the wind direction is vertical to the surface of the wood veneer, the wind speed is 15-20 m/S, after 30 minutes, stopping introducing the hot air, opening the door of the first drying chamber, and conveying the wood veneer subjected to the first drying treatment to a second drying chamber;

step S3, a second drying treatment stage, namely, after the wood veneer subjected to the first drying treatment is conveyed into a second drying chamber, closing a door of the second drying chamber, raising the temperature in the second drying chamber to 70 ℃, keeping the humidity in the second drying chamber at 40% -45%, introducing hot air to the surface of the wood veneer, wherein the wind direction is vertical to the surface of the wood veneer, the wind speed is 15-20 m/S, after 20 minutes, stopping introducing the hot air, opening the door of the second drying chamber, and conveying the wood veneer subjected to the second drying treatment to a third drying chamber;

step S4, a third drying treatment stage, namely, after conveying the wood veneer subjected to the second drying treatment into a third drying chamber, closing the third drying chamber and vacuumizing, keeping the vacuum degree of the third drying chamber between 0.01MPa and 0.05MPa, synchronously introducing pure nitrogen to replace gas in the third drying chamber, heating two hot pressing plates in the third drying chamber, controlling the heating temperature to be between 100 and 110 ℃, controlling the hot pressing plates to pressurize the upper surface and the lower surface of the wood veneer, controlling the pressure range of pressurization to be between 0.2MPa and 0.3MPa, and keeping the pressurization time to be 5 minutes; after the pressurization is stopped, conveying the wood veneer dried for the third time into a balance drying chamber; the hot pressing plate is in a grid shape, and the grid-shaped hollow area on the hot pressing plate accounts for 30% -70% of the whole area;

step S5, in the stage of balanced drying treatment, after the wood veneer subjected to the third drying treatment is conveyed into the balanced drying chamber, the door of the balanced drying chamber is closed, the temperature in the balanced drying chamber is increased to 75 ℃, the humidity in the balanced chamber is kept at 50% -55%, after 30 minutes, the door of the balanced drying chamber is opened, and the wood veneer is conveyed out of the balanced drying chamber;

step S6, preserving health, keeping the dried wood veneer at room temperature for 5 days;

step S7, measuring the moisture content of the wood veneer after curing; comparing the measured value with a standard threshold value, and if the measured value is greater than the standard threshold value, repeating step S4; and if the measured value is smaller than the standard threshold value, obtaining a qualified product.

In the technical scheme, the moisture content in the wood veneer is effectively removed through three times of drying treatment, and the moisture resistance of the wood veneer is effectively enhanced; through the balanced drying treatment, the stress inside the wood veneer is effectively reduced or even eliminated, and the relative stability of the wood veneer is effectively enhanced; the wood veneer dried by the process method has high drying efficiency and high qualification rate; the wood veneer dried by the process method can be better applied to the production of plywood, solid wood composite floor base materials, container floors and the like, and the produced product has good moisture resistance, high structural stability and difficult deformation and cracking. In step S4, in the third drying stage, the wood is heated and dried by vacuum pumping, and nitrogen is continuously introduced to replace the gas in the third drying chamber, so that the evaporated water molecules generated by heating the wood by the hot pressing plate can be dissipated and discharged and replaced by the introduced nitrogen, and the hot pressing plate and the wood directly contact with each other under the pressure of 0.2 MPa-0.3 MPa in the vacuum environment, thereby avoiding the problem of poor heat transfer efficiency in the vacuum environment and improving the heat transfer efficiency; the hot pressboard is latticed, and the problem that water molecules are difficult to disperse due to the fact that the whole hot pressboard is not provided with a hollow area is solved.

In a specific embodiment, the wood veneer has the following specifications: the length is 350 mm-450 mm, the width is 80mm, and the thickness is 2.0-2.5 mm.

In one embodiment, the specific measurement method of step S7 is as follows:

step S71, randomly extracting two wood veneers produced in the same batch;

step S72, respectively intercepting six samples with the length and the width of 20mm from the two extracted wood veneers;

step S73, measuring the weight m of the sample₁And recording;

step S74, putting the sample into an oven to be dried to be completely dry, and recording the weight m of the completely dry sample₀；

Step S75, calculating the water content of the sample; the water content formula is

Step S76, the calculated water content value W and the standard threshold value W₀Comparing; if the water content value W is larger than the standard threshold value W₀Then step S4 is repeated; if the water content value W is less than the standard threshold value W₀And obtaining qualified products.

The invention has the beneficial effects that: in the invention, the moisture content in the wood veneer is effectively removed through three times of drying treatment, and the moisture resistance of the wood veneer is effectively enhanced; through the balanced drying treatment, the stress inside the wood veneer is effectively reduced or even eliminated, and the relative stability of the wood veneer is effectively enhanced; the wood veneer dried by the process method has high drying efficiency and high qualification rate; the wood veneer dried by the process method can be better applied to the production of plywood, solid wood composite floor base materials, container floors and the like, and the produced product has good moisture resistance, high structural stability and difficult deformation and cracking; the drying quality is ensured, the drying rate is improved, and meanwhile, the drying energy consumption can be effectively reduced.

Drawings

Fig. 1 is a flow chart of a high-efficiency energy-saving veneer drying process method according to an embodiment of the present invention.

Detailed Description

The invention is further illustrated by the following examples in conjunction with the accompanying drawings:

as shown in fig. 1, which is a flow chart of a high-efficiency energy-saving veneer drying process method in an embodiment of the present invention, the method includes the following steps:

step S1, a preprocessing stage, namely performing rotary cutting and cutting on the log to obtain a wood veneer, and conveying the wood veneer into a first drying chamber through a conveying roller;

step S2, in the first drying treatment stage, after the wood veneer is conveyed into the first drying chamber, closing a door of the first drying chamber, raising the temperature in the first drying chamber to 60 ℃, keeping the humidity in the first drying chamber at 50% -55%, introducing hot air to the surface of the wood veneer, wherein the wind direction is vertical to the surface of the wood veneer, the wind speed is 15-20 m/S, after 30 minutes, stopping introducing the hot air, opening the door of the first drying chamber, and conveying the wood veneer subjected to the first drying treatment to a second drying chamber;

it is worth mentioning that when the high-speed hot air flows parallel to the surface of the veneer, friction is generated between the high-speed hot air flows and the high-speed hot air flows so that the air flow speed is reduced, the air flow speed of a thin layer in contact with the surface of the veneer is close to zero, and the water vapor presenting stagnation and the air form a layer of film to separate the hot air flow from the surface of the veneer, and the layer of film is called an interface layer; the interface layer influences the heat exchange efficiency and reduces the escape rate of moisture in the veneer, and high-speed hot air flow is sprayed perpendicular to the surface of the veneer to form a strip flow on the surface of the veneer so as to break or disturb the interface layer, improve the heat transfer efficiency, accelerate the surface evaporation and the diffusion of internal moisture, and remarkably accelerate the drying process.

Step S3, a second drying treatment stage, namely, after the wood veneer subjected to the first drying treatment is conveyed into a second drying chamber, closing a door of the second drying chamber, raising the temperature in the second drying chamber to 70 ℃, keeping the humidity in the second drying chamber at 40% -45%, introducing hot air to the surface of the wood veneer, wherein the wind direction is vertical to the surface of the wood veneer, the wind speed is 15-20 m/S, after 20 minutes, stopping introducing the hot air, opening the door of the second drying chamber, and conveying the wood veneer subjected to the second drying treatment to a third drying chamber;

step S4, a third drying treatment stage, namely, after conveying the wood veneer subjected to the second drying treatment into a third drying chamber, closing the third drying chamber and vacuumizing, keeping the vacuum degree of the third drying chamber between 0.01MPa and 0.05MPa, synchronously introducing pure nitrogen to replace gas in the third drying chamber, heating two hot pressing plates in the third drying chamber, controlling the heating temperature to be between 100 and 110 ℃, controlling the hot pressing plates to pressurize the upper surface and the lower surface of the wood veneer, controlling the pressure range of pressurization to be between 0.2MPa and 0.3MPa, and keeping the pressurization time to be 5 minutes; after the pressurization is stopped, conveying the wood veneer dried for the third time into a balance drying chamber; the hot pressing plate is in a grid shape, and the grid-shaped hollow area on the hot pressing plate accounts for 30% -70% of the whole area;

step S5, in the stage of balanced drying treatment, after the wood veneer subjected to the third drying treatment is conveyed into the balanced drying chamber, the door of the balanced drying chamber is closed, the temperature in the balanced drying chamber is increased to 75 ℃, the humidity in the balanced chamber is kept at 50% -55%, after 30 minutes, the door of the balanced drying chamber is opened, and the wood veneer is conveyed out of the balanced drying chamber;

step S6, preserving health, keeping the dried wood veneer at room temperature for 5 days;

step S7, measuring the moisture content of the wood veneer after curing; comparing the measured value with a standard threshold value, and if the measured value is greater than the standard threshold value, repeating step S4; and if the measured value is smaller than the standard threshold value, obtaining a qualified product.

In this embodiment, the wood veneer has the following specifications: the length is 350 mm-450 mm, the width is 80mm, and the thickness is 2.0-2.5 mm.

In this embodiment, the specific measurement method of step S7 is as follows:

step S71, randomly extracting two wood veneers produced in the same batch;

step S72, respectively intercepting six samples with the length and the width of 20mm from the two extracted wood veneers;

step S73, measuring the weight m of the sample₁And recording;

step S74, putting the sample into an oven to be dried to be completely dry, and recording the weight m of the completely dry sample₀；

Step S75, calculating the water content of the sample; the water content formula is

Step S76, the calculated water content value W and the standard threshold value W₀Comparing; if the water content value W is larger than the standard threshold value W₀Then step S4 is repeated; if the water content value W is less than the standard threshold value W₀And obtaining qualified products.

Specific embodiments of the present invention have been described above in detail. It is to be understood that the specific embodiments of the present invention are not exclusive and that modifications and variations may be made by one of ordinary skill in the art in light of the spirit of the present invention, within the scope of the appended claims. Therefore, technical solutions that can be obtained by a person skilled in the art through logic analysis, reasoning or limited experiments based on the prior art according to the embodiments of the present invention should be within the scope of protection defined by the claims.