ABS sheet extrusion molding process control points
DATE：2019/8/2 12:07:16 / READ： / SOURCE：This station
ABS sheet extrusion molding process control points
(1) Feeding. The material should be fed in time to ensure that the hopper is not empty, in order to prevent the air from directly entering the dry circulation system, affecting the return air speed. Different raw materials can not be mixed, pay attention to the grades and types of materials. In addition, the folding bag should be carried out outside the hopper to prevent the ropes and debris from being mixed into the hopper, causing the cutting port to clog or jam the batching tray.
(2) Drying. When drying, the temperature setting is required to be correct, and the temperature of the tank is guaranteed to reach the set value. At the same time, check whether the heat and air volume are normal. It is necessary to ensure that there is sufficient circulating air volume, that is, the circulating pipeline is sealed, the filter is not blocked, and the fan is operating normally. And check the drying parameters regularly (such as once every 4h)
(3) Ingredients. The batching time is set correctly, so that the batching motor runs normally, ensuring smooth feeding.
(4) Extrusion molding.
1 The processing temperature, especially the temperature in the barrel area and the die area, should be set reasonably. The temperature of the feed section should not be too high, in order to prevent the pellets from melting too early, the feed should be: the temperature of the exhaust section should be higher, which is beneficial to the exhaust; and the temperature of the second metering section should not be too high to reduce the melt pressure fluctuation. In addition, due to different plate types, the width of the die is not the same, should pay attention to adjust the temperature on both sides of the die; the mold temperature should not be too high to prevent discoloration. The temperature should be set reasonably. If the temperature is too high, the whole plate is lifted off; and when the temperature is too low, the edge of the plate is away from the roller.
2 Control the vacuum to the specified value so that the vacuum port is not blocked to ensure the exhaust effect.
3 Preheat before starting the machine. After each heating temperature reaches the set value and the temperature is constant at 0.Sh, it can be turned on. When starting up, according to the load and melt pressure conditions, slowly increase the screw speed, avoid one step in place; if the screw has been emptied, the screw speed must be controlled below 10r/min at the beginning, until the melt pressure rises rapidly. Accelerate to protect the device. Before shutting down, the heat preservation mode should be adopted to shut down the material temperature after the temperature is lowered to the holding temperature, which can reduce the degree of carbonization decomposition of the materials in the machine.
4 The opening degree of the die should be suitable, one is 115%-130% of the thickness of the plate, especially when the thin plate is extruded, if the opening degree is too large, the lateral distribution of the thickness of the plate village will be uneven.
5 filter screen generally uses 3 layers - 5 layers (1 layer is 180um copper mesh, the rest is 125um steel mesh), it is required to change once every 12h. If the extrusion is stable and there is no impurity, the time can be extended appropriately. Change the net whenever there are more impurities or the melt pressure before the net exceeds the specified value.
(1) Feeding. The material should be fed in time to ensure that the hopper is not empty, in order to prevent the air from directly entering the dry circulation system, affecting the return air speed. Different raw materials can not be mixed, pay attention to the grades and types of materials. In addition, the folding bag should be carried out outside the hopper to prevent the ropes and debris from being mixed into the hopper, causing the cutting port to clog or jam the batching tray.
(2) Drying. When drying, the temperature setting is required to be correct, and the temperature of the tank is guaranteed to reach the set value. At the same time, check whether the heat and air volume are normal. It is necessary to ensure that there is sufficient circulating air volume, that is, the circulating pipeline is sealed, the filter is not blocked, and the fan is operating normally. And check the drying parameters regularly (such as once every 4h)
(3) Ingredients. The batching time is set correctly, so that the batching motor runs normally, ensuring smooth feeding.
(4) Extrusion molding.
1 The processing temperature, especially the temperature in the barrel area and the die area, should be set reasonably. The temperature of the feed section should not be too high, in order to prevent the pellets from melting too early, the feed should be: the temperature of the exhaust section should be higher, which is beneficial to the exhaust; and the temperature of the second metering section should not be too high to reduce the melt pressure fluctuation. In addition, due to different plate types, the width of the die is not the same, should pay attention to adjust the temperature on both sides of the die; the mold temperature should not be too high to prevent discoloration. The temperature should be set reasonably. If the temperature is too high, the whole plate is lifted off; and when the temperature is too low, the edge of the plate is away from the roller.
2 Control the vacuum to the specified value so that the vacuum port is not blocked to ensure the exhaust effect.
3 Preheat before starting the machine. After each heating temperature reaches the set value and the temperature is constant at 0.Sh, it can be turned on. When starting up, according to the load and melt pressure conditions, slowly increase the screw speed, avoid one step in place; if the screw has been emptied, the screw speed must be controlled below 10r/min at the beginning, until the melt pressure rises rapidly. Accelerate to protect the device. Before shutting down, the heat preservation mode should be adopted to shut down the material temperature after the temperature is lowered to the holding temperature, which can reduce the degree of carbonization decomposition of the materials in the machine.
4 The opening degree of the die should be suitable, one is 115%-130% of the thickness of the plate, especially when the thin plate is extruded, if the opening degree is too large, the lateral distribution of the thickness of the plate village will be uneven.
5 filter screen generally uses 3 layers - 5 layers (1 layer is 180um copper mesh, the rest is 125um steel mesh), it is required to change once every 12h. If the extrusion is stable and there is no impurity, the time can be extended appropriately. Change the net whenever there are more impurities or the melt pressure before the net exceeds the specified value.
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