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A Method for Reducing Drying Shrinkage of Wood Horizontal Grain

A wood shrinkage technology, applied in wood heating, wood treatment, wood heat treatment, etc., can solve the problems of wood strength loss, high cost, uneven treatment process, etc., and achieve the effect of reducing deformation and shrinkage difference

Active Publication Date: 2020-11-10
NANJING FORESTRY UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the problems of loss of wood strength, uneven treatment process, complex production process and high cost in the prior art, and provide a simple and efficient process method to reduce the dry shrinkage of wood transverse grain , and the degree of reduction is controllable and uniform beneficial effect

Method used

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  • A Method for Reducing Drying Shrinkage of Wood Horizontal Grain

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Step 1, using eucalyptus wood and adjusting its moisture content to 30%.

[0026] Step 2, place the eucalyptus in step 1 in a drying kiln, adjust the temperature in the kiln to 50°C, and slowly reduce the moisture content of the eucalyptus in this temperature environment; Apply a fixed pressure, the pressure value is 15% of the limit of elastic ratio along the grain.

[0027] In step three, the moisture content of the eucalyptus in step two is reduced to 15%, and the fixed pressure is continuously applied.

[0028] Step 4, place the eucalyptus in step 3 under vacuum conditions for flash heat treatment, the temperature is 160° C., the time is 10 minutes, the vacuum degree is 0.01 MPa, and the fixed pressure is continuously applied.

[0029] Step 5, after cooling the wood in step 4, fix the length, width and thickness, and inspect.

Embodiment 2

[0031] Step 1, adopt Chinese fir wood, and adjust its moisture content to 20%.

[0032] Step 2, put the fir in step 1 in an oven, adjust the temperature in the kiln to 70°C, and slowly reduce the moisture content of the fir in this temperature environment; while reducing the moisture content, apply fixation to the length and width of the fir. Pressure, the pressure value in the length direction is 5% of the elastic proportional limit along the grain, and the pressure value in the width direction is 10% of the transverse elastic proportional limit.

[0033] In step three, the moisture content of the Chinese fir in step two is reduced to 10%, and the fixed pressure is continuously applied.

[0034] Step 4, place the Chinese fir in step 3 under vacuum conditions for flash heat treatment, the temperature is 180°C, the time is 5min, the vacuum degree is 0.05MPa, and the constant pressure is continuously applied;

[0035] Step 5, after cooling the wood in step 4, fix the length, wi...

Embodiment 3

[0037] Step 1, adopt sylvestris pine wood, and adjust its moisture content to 30%.

[0038] Step 2, the sylvestris sylvestris in step 1 is placed in a constant temperature and humidity box, and the temperature in the kiln is adjusted to be 40°C, so that the sylvestris sylvestris slowly reduces the moisture content in the temperature environment; while reducing the moisture content, the A fixed pressure is applied in the length and thickness directions of Pinus sylvestris pine, the pressure value in the length direction is 10% of the elastic proportional limit along the grain, and the pressure value in the thickness direction is 10% of the transverse elastic proportional limit.

[0039] Step 3, reducing the moisture content of Pinus sylvestris in Step 2 to 8%, and applying constant pressure continuously.

[0040] Step 4, place the sylvestris sylvestris in step 3 in a vacuum condition for flash heat treatment, the temperature is 200°C, the time is 10min, the vacuum degree is 0.0...

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Abstract

The invention discloses a method for reducing air shrinkage of wood grains in the transverse direction. The method comprises the following steps: step 1, adjusting a water content of wood to 20%-30%;step 2, placing the wood in the step 1 in a drying kiln or a temperature and humidity regulator or an oven, and adjusting environment temperature to make the wood slowly reduce the water content in the environment; and applying fixed pressure to the wood while reducing the water content; step 3, reducing the water content of the wood in the step 2 to adapt to a target use condition, and continuously applying fixed pressure; step 4, placing the wood in the step 3 in a vacuum condition, performing flash-type heat treatment, and continuously applying fixed pressure; and step 5, after the wood inthe step 4 is treated, performing cooling, determining a length, a width and a thickness, and performing a test. The method provided by the invention has the beneficial effects of realizing reductionof the air shrinkage of the wood grains in the transverse direction, and having a controllable and uniform reduction degree.

Description

technical field [0001] The invention belongs to the field of wood physical properties, and in particular relates to a method for reducing the drying shrinkage of wood transverse grains. Background technique [0002] Shrinkage is an inherent property of wood. When the moisture content of the wood is below the fiber saturation point, the reduction of the moisture content of the wood will cause the reduction of the size of the wood, that is, shrinkage. When wood shrinks, wood volume is lost and production costs increase. In addition, wood is an anisotropic material, and there are differences in shrinkage in different directions: the shrinkage along the grain is very small, no more than 0.3%; but the shrinkage in the transverse grain is large, from 3% to 12%, so When the moisture content changes, the wood shrinks and easily causes different forms of cracking and warping. For engineered wood components, the shrinkage of wood caused by changes in moisture content will loosen an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B27K5/00
CPCB27K5/001B27K5/0085
Inventor 詹天翼李婷陈凯文刘治廷吕超李万兆丁涛张耀丽张海洋卢晓宁
Owner NANJING FORESTRY UNIV
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