What are the factors that affect the heat treatment effect?
Factors affecting the heat treatment effect
The Swedish process uses high-temperature steam as a shielding gas. The design and properties of the heat-treated drying kiln are similar to those of ordinary sawn wood drying kilns. The steam generated by the steam generator is mixed with the water in the water spray device above the pile, and after being electrically heated, the wind is sent to the pile. The wood is dried and heat treated uniformly by changing the air flow direction.
2) Raw materials The most commonly used heat-treated wood species are: pine, spruce, birch, and European poplar. Generally, coniferous trees used for waterproof structures are treated to a greater extent; broadleaf trees used for interior decoration are treated lightly to ensure color and surface quality. Further, the resin having a high density is relatively difficult to handle, and is easily cracked during heat treatment, and the mechanical properties are lowered.
In the heat treatment, the resin will flow out and the equipment will be easily stained; the spruce tree knot and the annual ring will easily become loose after heat treatment, causing the annual ring to protrude when planing; the birch needs low temperature heat treatment to avoid the distortion of the plate surface; After the study is uneven, prone to cleft palate.
3) Saw method For coniferous wood, the traditional cutting method with the annual ring parallel to the surface is easy to cause the annual ring to peel off. For example, when cutting, the angle between the annual ring and the wood surface is >45°, the deformation amount can be reduced, the surface hardness is increased, and the performance is better.
The heat treatment time is usually determined based on the end use of the product. Studies have shown that the wood treated for 4h has better hygroscopic performance than 2h.