Key points of ABS extrusion molding process control
DATE：2021/9/8 8:31:40 / READ： / SOURCE：This station
Key points of ABS extrusion molding process control
(2) When drying, the temperature is required to be set correctly to ensure that the temperature of the material box reaches the set value. At the same time, check whether the heating and air volume are normal, and it is necessary to ensure that there is sufficient circulating air volume, that is, to make the circulating pipe sealed, the filter is not blocked, and the fan operates normally. And to check the drying parameters regularly (such as every 4h).
(3) The batching requires that the batching time is set correctly to make the batching motor run normally and ensure smooth feeding.
(4) Extrusion molding
1) The processing temperature, especially the temperature of the barrel area and die head area, should be set reasonably. The temperature in the feeding section should not be too high to prevent the pellets from melting too early and affecting the feeding; the temperature in the exhaust section should be higher to facilitate exhaust; and the temperature in the second metering section should not be too high to reduce melt pressure fluctuations. In addition, due to different plate types and different die widths, attention should be paid to adjusting the temperature on both sides of the die; the die lip temperature should not be too high to prevent discoloration. The temperature of the three rollers should be set reasonably. If the temperature is too high, the entire plate will leave the roller, and if the temperature is too low, the edge of the plate will leave the roller.
2) Control the vacuum degree to the specified value, so that the vacuum port is not blocked to ensure the exhaust effect.
3) Warm up before starting up, and wait for each heating temperature to reach the set value and keep constant temperature for 0.5h before starting up. When starting up, according to the load and melt pressure, slowly increase the screw speed, and do not step in place; if the screw has been emptied, the screw speed must be controlled below 10rmin at the beginning, and the melt pressure can only continue to accelerate when the melt pressure rises rapidly. To protect the equipment. Before shutting down, the heat preservation mode should be used, so that the temperature of the barrel can be reduced to the heat preservation temperature before shutting down, which can reduce the degree of carbonization and decomposition of the materials in the machine.
4) The opening of the die should be appropriate, generally 15% to 130% of the plate thickness, especially when extruding thin plates, if the opening is too large, the thickness of the plate will be unevenly distributed in the lateral direction.
5) The filter screen generally uses 3 to 5 layers (1 layer is 180m copper mesh, and the rest is 125m steel mesh), and it is required to be replaced every 12h. If the extrusion is stable and free of impurities, the time can be appropriately extended. When there are too many impurities or the melt pressure in front of the net exceeds the specified value, the net should be changed at any time.
6) The control of the tension of the sheet, in principle, is to adjust the difference between the linear speed of the three rolls and the speed of the chapter lead to 0.01-0.06mmin, and it is required that the sheet sags after passing the upper roll.
7) Cooling is small and flexible; the shearing machine requires the platform to be smooth and the knife edge is flat to prevent scratches on the bottom of the plate.
8) The process parameters should be checked every 2h, and the abnormalities should be adjusted in time.
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