2. Blockboard
1. Concept: Blockboard (commonly known as large core board, wood board) is a plywood with a solid wood core. Its vertical bending and compressive strength (distinguished by the direction of the core board) is poor, but its lateral bending and compressive strength is high. Most of the blockboards on the market are solid, glued, double-sided sanding, and five-layer blockboards, with a size of 1220 mm × 2440 mm.
2. Features: Blockboard has good screw holding force, high strength, firm quality, sound absorption, heat insulation, etc., and the moisture content is not high, between 10% and 13%, easy to process and the most widely used.
Blockboard is more stable than solid wood board, but it is afraid of moisture, so attention should be paid to avoid using it in kitchen and bathroom during construction.
The processing technology of blockboard is divided into two types: machine-made and hand-made. Hand-made is to manually insert wooden strips into the plywood. The extrusion force of the wooden strips is poor and cannot be processed according to cutting. It is only suitable for sub-projects of partial decoration. , such as the cushion wool board for solid wood floors. The machine-assembled plates are subject to large extrusion force, extremely small gaps, smooth splicing, uniform bearing capacity, and are not easily deformed after long-term use. The price of a good blockboard is between 70-140 yuan per sheet, and the poorer one is between 40-60 yuan. There are many kinds of materials for the inner core of blockboard, such as poplar, birch, pine, paulownia, etc. Among them, poplar and birch are the best, the texture is dense, the wood is not soft or hard, the nail holding force is strong, and it is not easy to deform. The texture of paulownia is soft, the water absorption is large, and it is not easy to dry. The hardwood is hard, not easy to be pressed, the splicing structure is not good, the nail holding force is not bad, and the deformation coefficient is also large.
3. Uses: furniture, doors and windows and sets, partitions, false walls, heating covers, curtain boxes, etc.
4. Selection: The surface of the blockboard should be flat, without warping, deformation, blistering and depression; the core strips are arranged evenly and neatly, the gap is small, and the core strips are free from decay, fracture, worm holes, knots, etc. Some blockboards cut corners, and the gap between the solid wood strips is large. If nails are nailed in the gap, there is basically no nail holding force. When consumers choose, they can look at the sun, and the gaps of the solid wood strips will be white. If the bonding strength of the blockboard is not good, there will be a "squeaking" sound of glue opening. If the large core board emits a fragrant wood smell, it means that the amount of formaldehyde released is less; if the smell is pungent, it means that the amount of formaldehyde released is more.
The quality of blockboard varies widely, and should be carefully checked when purchasing. First, check whether the core material is dense, whether there are obvious seams and decayed wood strips, and whether there are obvious seams and decayed wood strips. There may be insect eggs in the decayed wood strips, which are prone to moth-eaten in the future; then check whether there is any glue around. , The phenomenon of filling putty, this phenomenon is generally to make up for internal cracks or voids; secondly, tap the surface of the sheet with a sharp-nosed appliance, and listen to whether there is a big difference in the sound. If the sound changes, it means that there is a void inside the sheet. These phenomena will weaken the overall bearing capacity of the plate, and the uneven force for a long time will cause the plate structure to be distorted and deformed, affecting the appearance and use effect.
