Plywood hot press process
Before starting each shift and after stopping, check the leakage point of the oil circuit, check whether the operation of the motor and the pump valve is normal, and check whether the oil level is normal.
2. When the hot press starts production in the first shift of the week or from the shutdown state, it should be restarted to heat up, and the hot plate should be closed and steamed to preheat to the specified temperature.
3. Before entering the board, the garbage on the board must be removed, and the loose burrs around the board should be cleaned up.
4. Every time the board of one specification is replaced, the first group of hot-pressed boards after equipment maintenance and succession must be inspected, and batch-pressed boards can be carried out only after they are qualified.
5. Operation of hot pressing process
5.1 Plate loading, press closing and boosting stages
5.1.1 Quickly load the slab into the hot press, requiring the operator to cooperate with each other, the board must be straight, the board position is centered, and the top, bottom, left and right are symmetrical. 15 to 20 sheets are loaded each time.
5.1.2 Start the oil pump, quickly close the compressor, and increase the pressure to the specified value.
5.1.3 The above board loading, press closing and pressure increasing time shall be controlled within 1.5 minutes and shall not exceed 2 minutes.
5.2 Pressure holding stage
5.2.1 Carefully check the hot-pressing temperature, and control the temperature at 105-115°C according to the type of glue, the number of layers of plywood and the thickness of the slab.
5.2.2 The control pressure is 1.0-1.5MPa (10-16kg/cm2) according to the type of rubber, product density, plate quality, plate area and water content.
5.2.3 The hot-pressing time is controlled according to the type of rubber, the thickness of the slab, the moisture content of the slab, the pressure and the temperature of the hot-pressing. This time period is from when the pressure rises to the specified value to when the pressure is reduced. A rough estimate is that it takes 0.5 to 1.0 minutes per millimeter of plate thickness.
5.3 Depressurization, platen opening and unloading stages
5.3.1 Lower the hot pressing temperature first.
5.3.2 Use the slow pressure reduction method to slowly discharge the pressure in the hot press. Special care should be taken in the operation of the pressure reduction process, and the pressure reduction speed must be slow to ensure that the plywood will not be separated due to the excessive pressure difference between the inside and outside of the plate blank. Quality problems such as plate cracking and bubbling. The entire decompression process should take no less than 2 minutes.
5.3.3 Start to open the heat press platen.
5.3.4 Unload the plywood from the heat press. When unloading the board, the operator should pay attention to coordination and use the same force to avoid scratching and damaging the plywood.
6. The newly unloaded plywood should be parked on the plate rack to dissipate heat, and the time should not affect the unloading of the next batch of hot-pressed boards.
7. The thickness of the four corners of the hot-pressed plywood is measured, and the boards with unqualified quality such as ultra-thick, ultra-thin, plywood separation, surface plate rupture, bubbling, etc. are separately stacked and sent to designated points for repair.
8. After closing the board, fill in the production report carefully.
9. Precautions
9.1 The same hot pressing is strictly prohibited for boards of different specifications.
9.2 The operator shall not change the process parameters without authorization.
9.3 If the process parameter requirements change, the written notice shall prevail.
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