Bamboo plywood
It is made by bonding the thick bamboo pieces with grooves to form the unit. The bamboo pieces are prepared by the flat planing method. The "high temperature softening of the bamboo material" is the technical feature of the product. Bamboo plywood can be used as a common structural board or as a car floor by sheet length and surface treatment.
Process characteristics
1. Preparation of thick bamboo sheets with grooves
The large-diameter bamboo is cross-sectioned into bamboo segments, milled to the outer section and then longitudinally sectioned into 2-4 pieces, and then milled to the inner section for cooking and softening, and then heated and pressurized on the upper-pressure single-layer flat press to arc The shaped bamboo pieces are unfolded into a plane. Finally, it is processed into a thick bamboo piece without bamboo green or bamboo yellow by double-sided planing.
2, stereotype drying
In order to prevent the bamboo sheet from being curled and deformed under the lateral elastic restoring force during the drying process, it is necessary to adopt a pressure drying method and equipment to heat the wet bamboo sheet under pressure, and to eliminate the pressure when the pressure is released. Moisture and free shrinkage.
3, bamboo sizing
The bamboo roll was coated with a water-soluble phenolic resin glue by a four-roll coater, and the amount of the glue was 300-350 g/m2 (double-sided). 1% - 3% of flour, soy flour, etc. can be added to the adhesive as a filler. The filler can easily form a film on the surface after the glue is applied, and it is not easy to produce a glue phenomenon when hot pressed, and the brittleness of the glue layer can be improved after curing.
4, the blank
The manual blanking is adopted, and the blank is strictly carried out according to the principle of symmetry, the principle of odd layers and the principle that the texture of adjacent layers of bamboo is perpendicular to each other. The panel is required to be made of a good-quality bamboo piece, and the material of the second piece is used as a backing plate. The bamboo green of the surface and the back plate faces outward, and the bamboo yellow faces inward; when the core plate is assembled, the orientation of the adjacent bamboo pieces is required to be alternately arranged according to the bamboo green surface and the bamboo yellow surface.
5, pre-pressure and hot pressing
(1) Pre-compression In order to prevent defects such as lamination and separation caused by the displacement of the slab when the plate is placed in the hot press, the slab is pre-compressed at room temperature before hot pressing after the bundling. It is bonded into a unitary material.
(2) Hot pressing
The hot-hot glue bonding process has a hot pressing temperature of about 140oC and a unit pressure of 2.5-3.0 MPa. The hot pressing time is calculated according to the thickness of the finished product, and is generally 1.1 min/mm.
In order to prevent the "bubbling" phenomenon, a three-stage depressurization process is usually employed in the late stage of hot pressing. The first section is reduced from the working pressure to the "balanced pressure", the second section is reduced to "zero" by the "balanced pressure", and the third section is completed from zero to the hot platen.
6, the length and surface treatment of the board
Bamboo plywood is mainly used as the floor of the car, so the length of the plate is required to be consistent with the length of the car, and the pressed plate is shorter, so it needs to be lengthened.
The length and surface treatment of the sheet includes end milling bevel, bevel coating and lap joint, thermocompression length, longitudinal trimming, panel coating and overlay screen, and hot pressing to cure the panel Press out the process such as mesh marks.
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