The bending of plastic board surface may be caused by various reasons, such as processing technology, storage environment, etc. The corresponding solution can be selected according to the degree of bending and specific situation. The following are some common treatment methods: heating correction using a hot air gun: For some thermoplastic boards, such as PVC board, acrylic board, etc., a hot air gun can be used to evenly heat the curved surface of the plastic board. When heating, the distance between the hot air gun and the surface of the plastic board should be kept moderate, usually around 10-15 centimeters, and the moving speed should be uniform to avoid local overheating. When the plastic board becomes soft due to heat, quickly place it on a flat surface and press a heavy object on it to cool and solidify it. The cooling time depends on the thickness and material of the plastic board, and generally takes several minutes to more than ten minutes. Using oven heating: If the size or quantity of plastic sheets is large, they can be placed in an oven for heating correction. Set the oven temperature within the thermal deformation temperature range of plastic sheets, typically around 130-150 ℃ for PVC sheets and 160-180 ℃ for acrylic sheets. After heating for a period of time, wait for the plastic board to soften, take it out and place it on a flat platform to cool and shape under pressure. This method can make the plastic board heated more evenly and have better correction effect, but attention should be paid to controlling the temperature and heating time to prevent excessive deformation or damage of the plastic board. Mechanical correction using correction fixtures: For some slightly curved plastic sheets, specialized correction fixtures can be made or purchased. Place the plastic board into the fixture and restore its flatness through the external force of the fixture. The pressure of the fixture should be evenly distributed on the plastic board to avoid damage to the plastic board caused by excessive local pressure. The pressure and fixing time of the fixture can be adjusted appropriately according to the material and thickness of the plastic board. Rolling correction: If there is a rolling equipment, the bent plastic sheet can be rolled and corrected by a rolling machine. The roller spacing and pressure of the rolling machine should be adjusted according to the thickness and bending degree of the plastic sheet. During the rolling process, the plastic sheet is gradually restored to its flatness due to the squeezing and stretching effects of the rollers. The rolling speed should not be too fast, generally controlled at around 1-2 meters per minute to avoid new deformation of the plastic board due to uneven stress. Wet water treatment: For some plastic boards that bend due to moisture or uneven drying, wet water treatment can be used. Soak the plastic board in water for a period of time to fully absorb moisture and release the internal stress of the board. The soaking time depends on the material and thickness of the plastic board, and generally takes several hours to more than ten hours. Then remove the plastic board, dry the surface moisture with a dry cloth, and place it on a flat surface to air dry naturally. During the air drying process, the plastic board may gradually regain its flatness. But this method is not applicable to plastic board materials that are not water-resistant, such as polystyrene boards. Adjust storage environment: If the plastic board is bent due to improper storage environment, such as long-term storage in high temperature, humidity, or direct sunlight, the storage environment should be adjusted in a timely manner. Store the plastic board in a place with suitable temperature (usually 15-25 ℃), moderate humidity (relative humidity between 40% -60%), and good ventilation, avoiding direct sunlight and proximity to heat sources. For bent plastic sheets, after being stored in a new environment for a period of time, they may recover due to the gradual balance of internal stress. At the same time, when storing, pay attention to stacking the plastic boards flat to avoid being squeezed by external forces. If the bending degree of the plastic board is very severe and cannot be restored to flatness after the above methods are used, or if the plastic board has extremely high requirements for flatness during use and cannot meet the requirements through simple processing, then it may be necessary to consider replacing it with a new plastic board.
