CN102814842A - High-strength thick laminated veneer lumber and manufacturing method thereof - Google Patents

Abstract

This technology provides a high-strength thick laminated veneer lumber with simple structure, low cost and excellent mechanical properties. The high-strength thick laminated veneer lumber of this technology is made of multi-layer veneer glue coating, billet formation, and pressure gluing. Carbon fiber cloth is arranged between the two layers of veneers in the middle.

Description

High-strength thick laminated veneer lumber and its preparation method

technical field

This technology relates to laminated veneer lumber and its preparation method. Specifically, it is a method for manufacturing Italian high-strength and thick laminated veneer lumber with carbon fiber reinforced high-strength and thick laminated veneer lumber and microwave heating. Structural wood-based panel manufacturing field.

Background technique

Laminated veneer lumber is a new high-performance structure made of small-diameter logs, which are laminated with multi-layer glue, along the grain (or horizontal grain veneer can be added), and glued together after rotary cutting. Material. It not only retains many good natural advantages of wood, but also has uniform structural characteristics, small strength variation, high allowable stress, far more than sectioned wood, close to no-section wood, good dimensional stability, and better strength-to-weight ratio than steel , easy to process, and has good stability and shock resistance. In the past ten years, developed countries in Europe and the United States, Japan and South Korea have generally used laminated veneer lumber as packaging materials for mechanical and electrical products. However, due to our backward technology in the manufacture of thick laminated veneer lumber, a large amount of solid wood is used for electromechanical packaging, resulting in a great waste of forest resources.

When preparing laminated veneer lumber, the general method is to cut the wood into veneers, dry the veneers (up to a certain moisture content), apply glue on the veneers, and form blanks; then cold press and glue. In this method, the veneers need to be dried, and the time for cold pressing and gluing is very long (about 24 hours), and the preparation efficiency is very low.

Contents of the invention

The purpose of this technology is to provide a high-strength and thick laminated veneer lumber with simple structure, low cost and excellent mechanical properties.

The high-strength thick laminated veneer lumber of this technology is made of multi-layer veneer gluing, billet formation, and pressure gluing. Carbon fiber cloth is arranged between the two layers of veneers in the middle.

In the above-mentioned high-strength and thick laminated veneer lumber, the veneer is Italian poplar veneer, and the thickness of the veneer is greater than 2mm.

This technology also provides the above-mentioned high-strength and thick laminated veneer lumber preparation method, which has no requirement on the moisture content of the veneer (no need to dry the veneer), and has high production efficiency.

The preparation method of the high-strength thick laminated veneer lumber of this technology is to cut the wood into veneers, apply glue on the veneers, and assemble the billets; Temperature 130-150°C, pressure 1.0-1.2MPa; during billet assembly, set between the first and second veneers, between the penultimate and second veneers, and between the middle two veneers There is carbon fiber cloth; when applying glue, phenolic resin is used between the veneers, and epoxy resin is used between the veneer and carbon fiber cloth.

In the above preparation method, Italian poplar is selected as the wood, and the thickness of the Italian poplar veneer is preferably greater than 2 mm.

In the above preparation method, the amount of glue applied to both sides of the veneer is 250-300g/m ² .

Beneficial effects of this technology: 1. This technology is only provided with carbon fiber cloth between the first and second layers of veneers, between the penultimate first and second layers of veneers, and between the middle two layers of veneers. Carbon fiber cloth is not arranged between each layer of veneers. This technology saves the amount of carbon fiber cloth used, but after testing, its mechanical properties are not much different from those of laminated veneer lumber in which carbon fiber cloth is arranged between each layer of veneer. 2. There is no requirement for the moisture content of the veneer, and no drying is required during preparation, which saves the process. 3. Using a microwave press for hot-pressing and gluing, with high efficiency. Microwave is a kind of electromagnetic wave, which can heat the inside and outside of the material at the same time. In addition, it can selectively heat different components of the material, so that the heat transfer efficiency is greatly improved. It only takes 15-30 minutes to manufacture thick laminated veneer lumber greater than or equal to 20cm. Compared with the gluing time of more than 24h by the cold pressing method, the efficiency is significantly improved.

Description of drawings

Figure 1 is a schematic diagram of the high-strength thick laminated veneer lumber.

Detailed ways

Example 1: Preparation of high-strength thick laminated veneer lumber

1. Preparation of poplar veneer. The process is: Italian poplar logs-cutting-softening of wood segments-peeling-rotary cutting-shearing-repairing-oblique grinding. The thickness of Italian poplar veneer is 3mm, and the moisture content does not need special control.

2. Glue the Italian poplar veneers, use phenolic resin between adjacent veneers, and use epoxy resin between veneers and carbon fiber cloth. The amount of glue applied on both sides of the veneer is 250-300g/m ² .

3. Assemble the 20-layer Italian poplar veneer along the grain, see Figure 1, and place the three-layer carbon fiber cloth 7 between the first layer of veneer 1 and the second layer of veneer 2, and between the tenth layer of veneer 3 and the Between veneers 4 on the 11th floor, between veneers 5 on the 19th floor and veneers 6 on the 20th floor.

4. Hot pressing on a microwave press at a temperature of 130-150°C, a pressure of 1.0-1.2 MPa, and a microwave output power of 3.5-10KW, with a hot-pressing speed of about 0.4mm/min.

5. Cool the hot-pressed product and cut it into a rectangular cuboid wooden beam (the thickness of the wooden beam in the direction perpendicular to the veneer is the same as the thickness after cooling).

Comparative example 1:

The difference between the preparation of Comparative Example 1 and that of Example 1 is that carbon fiber cloth is arranged between adjacent veneers, and the adhesive is epoxy resin (no phenolic resin). Others are the same as in Example 1.

Comparative example 2:

The difference between the preparation of Comparative Example 2 and that of Example 1 is that there is only one layer of carbon fiber cloth, and this layer of carbon fiber is arranged between the 10th veneer and the 11th veneer. Others are the same as in Example 1.

Comparative example 3:

The difference between the preparation of Comparative Example 3 and that of Example 1 is that there are only two layers of carbon fiber cloth, and the two layers of carbon fiber cloth are respectively placed between the first layer of veneer and the second layer of veneer, and between the 19th layer of veneer and the second layer of veneer. Between veneers on the 20th layer. Others are the same as in Example 1.

The wooden beams obtained by sawing in Example 1 and each comparative example (the widths of the wooden beams are relative and the lengths are equal) were tested for mechanical properties, and the results are shown in Table 1.

Table 1

the Example 1 Comparative example 1 Comparative example 2 Comparative example 3 Static Bending Strength MPa 85 90 65 80 Elastic modulus GPa 10.1 12.35 7.0 8.5

This technology makes full use of the advantages of carbon fiber materials, Italian poplar wood, and microwave heating, and can obtain the following three benefits: First, the reasonable arrangement of carbon fiber materials greatly improves the mechanical properties of Italian poplar wood and saves costs, which can be increased by 30-40%. The bearing capacity; the plate produced by this method has reasonable structure and superior performance. The second is to increase the added value and technological content of Italian poplar production, greatly expanding the application field of Italian poplar; the second is microwave heating with high efficiency.

The high-strength and thick laminated veneer lumber is manufactured with Italian poplar as the base material to make full use of the fast-growing poplar resources with a wide planting range. Its physical and mechanical properties have been greatly improved, and at the same time, the yield rate is high, and the economic benefits are significant; compared with solid wood, high-strength and thick laminated veneer lumber has designability, and structural design can be carried out according to actual use conditions; in addition, microwave technology The application greatly shortens the manufacturing cycle of thick laminated veneer lumber, and improves production efficiency and quality.

Claims (7)

1. High-strength thick laminated veneer lumber, made of multi-layer veneer gluing, billet formation, and pressure gluing. Its characteristics are: between the first and second layers of veneers, and between the penultimate and second layers Carbon fiber cloth is arranged between the veneers and between the two layers of veneers in the middle. 2. The high strength and thick laminated veneer lumber according to claim 1, characterized in that: said veneer is Italian poplar veneer. 3. The high strength and thick laminated veneer lumber according to claim 2, characterized in that: the thickness of the veneer is greater than 2mm. 4. The preparation method of the high-strength thick laminated veneer lumber described in claim 1 is characterized in that: the wood is rotary cut into veneers, glue is applied on the veneers, and the billets are assembled; hot pressing on a microwave press for 15 —30min is enough, when hot pressing, the temperature is 130-150°C, and the pressure is 1.0-1.2MPa; when forming the billet, between the first and second veneers, between the penultimate and second veneers, and in the middle Carbon fiber cloth is arranged between the two layers of veneers; when gluing, phenolic resin is used between the veneers, and epoxy resin is used between the veneers and carbon fiber cloth. 5. The method for preparing high-strength thick laminated veneer lumber according to claim 4, characterized in that: poplar is selected as the timber. 6. The method for preparing high-strength and thick laminated veneer lumber as claimed in claim 5, wherein the thickness of the poplar veneer is greater than 2mm. 7. The method for preparing high-strength and thick laminated veneer lumber according to claim 4, characterized in that: the amount of glue applied on both sides of the veneer is 250-300g/m ² .

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