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What factors affect wood cracks?
Date:
2022-05-06
The natural disadvantages of ordinary building square wood include knots, fading, bug eyes, cracks, etc.
The natural disadvantages of ordinary building square wood include knots, fading, bug eyes, cracks, etc. These can all cause damage to spraying, so be sure to remove and salvage before spraying.
Cracks are due to the influence of external force or temperature on the wood. The hazards of environmental humidity changes cause chemical fibers to separate from each other. There are several ways to crack wood: surface cracks, internal cracks, end cracks, and wheel cracks.
1. Surface crack:
Refers to surface cracks, surface cracks refer to the cracks on the surface of the log itself or the adult. Cracks are usually confined to the chord surface and develop axially. When wood dries, moisture evaporates from the surface first.
When the surface water content drops below the chemical fiber saturation point, the surface wood just begins to close, but at this time the moisture content of the temporary inner wood is still around the chemical fiber saturation point, and no closing occurs. The closure of the surface wood is limited by the inner layer of wood and cannot be closed at will, thus creating thermal stress in the wood: the surface wood is pulled and the inner layer of wood is stressed. The stronger the drying criterion, the greater the difference in moisture content of the wood on the inner surface and the greater the thermal stress. If the tensile stress of the surface exceeds the longitudinal compressive strength of the wood, the wood mechanism is torn, because the compressive strength of the radiation mechanism along the wood is less than that of the adjacent bamboo charcoal fibers, so the gap is first caused by the wood radiation.
2. Internal fissure:
That is, internal cracks. Internal cracks are also commonly referred to as honeycomb cracks. Internal cracks are caused by dry, irritable mid-to-late and sometimes dry, irritable raw material storage stages. From the outside world of wood, it is generally not easy to spot, but more seriously, it can be distinguished by dents on the surface of the material. Internal cracks are caused by tensile stress in the inner layer of wood.
3. End split:
That is, the inner hole crack. End cracks are either limited to the inner holes of the wood or extend to one or both sides of the top, the latter often referred to as cracks. The key reason is that the water conductivity of wood is far beyond the direction of the longitudinal lines. When wood dries, water evaporates much faster from the inner pores than from the sides. The water content at the top is less than that in the central and southern parts, and the top concentration is limited by the wood in the central and southern parts, causing tensile (extension) stress at the top. When the tensile stress exceeds the longitudinal compressive strength of the wood, the inner hole cracks.
4. Wheel cracks:
This gap develops in the direction of the growth rings, often extending to many adjacent growth rings. Wheel cracks generally occur in the early stages of the drying impulse, appearing in the inner pores of the wood, and the cracks increase as the drying impulse progresses. lengthened. Sometimes it occurs internally, but it occurs in the middle and late stages of the drying impulse, due to the severe internal tensile stress.
Countermeasures to solve wood cracks.
1. Select high temperature qualitative treatment:
The method of reducing internal cracks in wood can be qualitatively treated with high temperature. Before the entire drying process is completed, the wood can be treated with high temperature, high temperature and low temperature to remove the residual deformation on the surface of the internal cracked wood.
When the solution is made, the residual deformation of the wood surface is reduced due to the rising humidity, which is opposite to the original extended residual deformation, thereby removing the cracks in the wood.
2. Mechanical method to prevent rust:
Place thin wire to tie the edges on dry, dry wood, using rust-proof rings. Forming pegboards, etc., mechanically forcing the wood to not need to rise and close, also prevents the wood from cracking.
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