Hot pressing is a key process in the production of particleboard. The function is to solidify the rubber in the slab and to pressurize the loose slab to form a sheet of specified thickness. The process requirements are: 1 appropriate moisture content. When the surface water content is 18-20%, it is beneficial to improve the bending strength, tensile strength and surface finish, and reduce the possibility of slab bubbling delamination during pressure relief. The core layer moisture content should be suitably lower than the surface layer to maintain proper planar tensile strength. 2 appropriate hot pressing pressure. The pressure can affect the contact area between the shavings, the thickness deviation of the sheet and the degree of rubber transfer between the shavings. According to the different density requirements of the product, the hot pressing pressure is generally 1.2 to 1.4 MPa. 3 appropriate temperature. If the temperature is too high, not only the urea-formaldehyde resin will be decomposed, but also the slab partially solidified in advance to cause waste when the temperature is raised. 4 appropriate pressurization time. When the time is too short, the middle layer resin cannot be sufficiently cured, the elastic recovery of the finished product in the thickness direction is increased, and the plane tensile strength is remarkably lowered. After hot pressing, the particleboard should be treated for a period of time to adjust the moisture content to equilibrium, then saw sanding and inspection of the packaging. However, it cannot be stacked in a hot state after pressure relief, otherwise it will increase the brittleness of the board.
Molding technology refers to the technique of forming a product in one operation. There are three mature processes. The hot mold method can use less rubber compound or no rubber compound, and activate the flow in the closed hot mold by lignin, and it needs to be cooled and demolded. The heat consumption is large and the productivity is low, which has been gradually eliminated. The box molding method is to pressurize with a special press and pressurize the product to make a package. The hot press forming method mainly manufactures furniture fittings, interior fittings and pallets, etc. The adhesive is mainly urea-formaldehyde resin, and the surface of the product is laminated with a veneer or resin impregnated paper, once formed.
Further, there is a planar molding method in which a surface of a finished particle board or a formed slab which is not subjected to hot pressing is pressed with a stencil to form a relief pattern.
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Traffic Barrier, also known as a boom gate, is a bar, or pole pivoted to allow the boom to block vehicular access through a controlled point. Typically the tip of a boom gate rises in a vertical arc to a near vertical position. Boom gates are often counterweighted, so the pole is easily tipped. Boom gates are often paired either end to end, or offset appropriately to block traffic in both directions. Some boom gates also have a second arm which hangs 300 to 400 mm below the upper arm when lowered, to increase approach visibility, and which hangs on links so it lies flat with the main boom as the barrier is raised. Some barriers also feature a pivot roughly half way, where as the barrier is raised, the outermost half remains horizontal, with the barrier resembling an upside-down L when raised.
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