Structural specification sawn timber grading method

A technology for structural and sawn timber, which is applied in the fields of engineering wood products and green prefabricated building materials, can solve problems such as difficult to meet the requirements of use, insufficient industrialization, expensive equipment, etc., and achieve simple and clear analysis process, good effect and low equipment investment. little effect

Inactive Publication Date: 2020-06-12
SOUTHWEST FORESTRY UNIVERSITY +1
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the above-mentioned methods all need special equipment, and the required equipment is expensive and the operation is also complicated.
Due to space and capital constraints, general enterprises have insufficient industrialization, so there are few manufacturers with standard sawn timber grading equipment
In addition, methods such as the stress wave (ultrasonic) method and the transverse vibration method have certain requirements for the size of the sawn timber. However, the sizes of the sawn timber produced in my country are various, and it is difficult to meet the requirements for use.

Method used

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  • Structural specification sawn timber grading method

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Embodiment 1

[0019] The invention discloses a method for grading sawn timber with specifications for structures. Taking the imported dried hem-fir (Hem-fir) structure with 2x6 inches (140x38mm) for offline grading as an example, the method includes the following steps:

[0020] S1. The length of dry hemlock-fir is 18 feet (5.4m), and the total number is 4500. Randomly select 50 hemlock-fir sawn timber samples. The number of samples randomly sampled is determined according to the allowable error and confidence level of the relevant mechanical performance indicators.

[0021] S2. Label, weigh and measure the moisture content of the above-mentioned 50 hemlock-fir specification sawn timber samples in sequence, and make records.

[0022] S3. After testing, the moisture content of the sample is between 8.5-15.3%, and the density distribution range is 310-560kg / m 3 . The selected standard lumber samples are cut from both ends according to the relevant standards to process the test pieces for t...

Embodiment 2

[0026] The invention discloses a method for grading sawn timber with specifications for structural use. Taking domestic dried Yunnan pine 140x40mm specification sawn timber as an example, the method comprises the following steps:

[0027] S1. The length of dried Yunnan pine is 8 feet (2.4m). Randomly select 56 samples of Yunnan pine sawn timber. The number of samples randomly sampled is determined according to the allowable error and confidence level of the relevant mechanical performance indicators.

[0028] S2. Label, weigh and measure the moisture content of the above 56 Yunnan pine sawn timber samples in sequence, and make records.

[0029] S3. After testing, the water content of the sample is between 8.5-15.3%, and the density distribution range is 450-585kg / m 3 . Then cut the selected standard lumber samples from both ends according to the relevant standards to process the test pieces for the bending test, and take 2 test pieces for each standard lumber sample, a tota...

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Abstract

The invention discloses a structural specification sawn timber grading method which comprises the following steps: S1, performing random representative sampling on specification sawn timber; S2, sequentially labeling, weighing and measuring the moisture content of the sawn timber sample, and performing calculating to obtain the density distribution of the standard sawn timber sample; S3, measuringrelated mechanical property indexes of the sawn timber sample; S4, obtaining a linear fitting equation between the specification sawn timber mechanical property index and the density through regression calculation, namely a specification sawn timber grading model; and S5, according to the model, testing the density of the standard sawn timber offline or online by setting a density grading threshold value or a grading interval, so that grading of the standard sawn timber is completed. According to the grading method, the structural specification sawn timber grading speed is high, the cost is low, and the precision is high.

Description

technical field [0001] The invention relates to the field of manufacturing engineering wood products and green prefabricated building materials, and more specifically relates to a method for grading sawn timber with specifications for structures. Background technique [0002] With the promotion and development of modern wood structures in my country, the consumption of structural sawn timber and new engineering wood products is increasing. These new engineered wood products, such as glued laminated timber (GLT) and cross-laminated timber (CLT), are produced by grading dry sawn timber and then rationally forming billets. Sawn timber grading is generally divided into two types: appearance grading and stress grading. Appearance grading is mainly based on defects on the surface of sawn timber, such as missing edges, knots, cracks, bending and decay, etc., while stress grading is generally based on the measurement of the elastic modulus of sawn timber. Improving the quality of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N9/36G01N3/20
CPCG01N9/36G01N3/20G01N2203/0023G01N2203/0075
Inventor 王建和李昊黄素涌卫佩行张龙彭思
Owner SOUTHWEST FORESTRY UNIVERSITY
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