Bamboo curtain (chord-oriented) plywood process characteristics

The string-to-bamboo curtain plywood is a product obtained by cutting the chord direction of the bamboo string, weaving the curtain and chord. Because there are bamboo green and bamboo yellow which are difficult to be glued in the chord direction of the bamboo, in order to obtain good gluing, it must be removed, which not only reduces the efficiency of the chord-cutting, but also greatly reduces the utilization rate of the bamboo.

1. Structure of bamboo curtain (chord direction)

The length direction of the long bamboo curtain is the longitudinal direction of the bamboo pole, the width direction is the chord direction of the bamboo pole, and the thickness direction is the radial direction of the bamboo pole.

2, wet bamboo curtain drying
The wet bamboo curtain can be dried by high temperature and rapid drying process. The temperature is 150~180°C and the time is 10~15min. This is because the bamboo raft of the chord is uniform, thin and narrow, and the possibility of high temperature dry deformation is small. In addition, the natural drying of the bamboo stalk has caused some water to evaporate during the processing, and the initial moisture content is low, so the drying time is also short.

Wet bamboo curtain drying can also be carried out in a dry kiln for periodic low-humidity drying. When drying, the bamboo curtains are stacked in a dry kiln or placed in a roll on a movable special multi-layer drying rack for drying at a temperature of 80-90 ° C and a drying time of about 24 h. The wet bamboo curtain is made into a roll kiln, which has low drying energy consumption and low cost, and the warp of the bamboo curtain is not easy to be broken, which is beneficial to the subsequent process. Therefore, the bamboo curtain kiln drying method is worth promoting.

3, bamboo curtain sizing
Bamboo curtain (chordwise) plywood is commonly used as an adhesive for phenolic resin. For the strip bamboo curtain, the method of continuous dipping is adopted in order to realize continuous production in several processes before and after. For the sizing of the whole bamboo curtain, dipping, roller coating and brushing can be used respectively.

4, slab structure and assembly
All the constituent units are bamboo curtains, and the slab structure is three symmetrical layers, each of which is perpendicular to each other, and the bamboo curtains of the same large layer are parallel to each other. The total thickness of the core bamboo curtain should be 25% to 30% of the thickness of the slab to ensure the lateral strength and shape stability of the sheet.

5, hot pressing process
The hot pressing temperature of phenolic resin bamboo curtain plywood is 135~145°C, the unit pressure is high pressure and low pressure first, and the pressure is slowly reduced from 4.0MPa to 3.0MPa. At the beginning of hot pressing, a short time high pressure is used to make the surface of the slab dense and flat, and most of the hot pressing time uses a lower pressure to control the density and thickness of the sheet.

Evaluation
(1) Bamboo curtain (chord-oriented) plywood can be considered as a product that is innovative in the structure and process of bamboo mat plywood and bamboo raft. Therefore, it not only overcomes the bamboo mat of the bamboo mat plywood, but also can not be mechanically woven. If the dipping method is used during the sizing, the bamboo raft overlap is easy to store the glue. If the roller coating and the brushing method are adopted, the bamboo raft overlap The phenomenon of lack of glue will occur, and if the combination of dipping and roller coating is used, the process is cumbersome and the like. It also avoids the shortage of bamboo slabs that can only be pressed into high-density slabs. At the same time, it also overcomes the fact that the slabs of bamboo slabs are easily deformed and can only produce special large-format sheets by the process of lengthening the finished products. More cumbersome and other characteristics.

(2) Bamboo curtain (chord-oriented) plywood can realize mechanized and continuous production from mechanical weaving, drying, dipping, drying to shearing process, so the production efficiency is high; semi-finished products (bamboo curtain) can also be used The long process replaces the current finished product lengthening process.

(3) The bamboo curtain (chord direction) plywood has excellent physical and mechanical properties, but the strip surface groove formed by the gap between the bamboo rafts and the warp of the bamboo curtain exist on the surface of the sheet, which affects both the appearance and the use. In order to overcome this structural disadvantage, one of two process measures can be used. One is to sand or scrape the surface of the bamboo curtain (chord-oriented) plywood; the other is to add a layer of bamboo mat (or wood veneer) to the upper and lower surfaces of the bamboo curtain (chord-oriented) plywood slab. Synthesize a bamboo mat (chord) plywood covered with bamboo mats (or wood veneers), and also add a layer of film paper to the bamboo mat (or wood veneer) to form a coating Plastic bamboo plywood.

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