Plastic extruder is a machine in the plastic extrusion production line. Only by mastering the key operation of the extruder can it be used correctly and reasonably. When using the screw extruder, we think that special attention should be paid to the following points:
1. Preparation before starting the machine
For plastics used for extrusion molding, the raw materials should meet the specified drying requirements, and the raw materials should be sieved to remove lumps and mechanical impurities.
Check whether the water, electricity, and gas systems of the equipment are normal, ensure that the water and gas circuits are unobstructed and leak-free, whether the electrical system is normal, and whether the heating system, temperature control, and various surface operations are reliable; conduct no-load and low-speed test runs of the auxiliary machine to investigate whether the equipment is operating normally; start the vacuum pump of the calibrating table to investigate whether it is working normally; lubricate the lubrication parts of various equipment. If any problems are found, they should be cleaned in time.
2. Start the machine
After the temperature is constant, the machine can be started. Before starting the machine, the bolts of the die head and the extruder should be tightened again to eliminate the difference in thermal expansion between the bolts and the die head.
After the plastic is extruded from the mold, the extrudate needs to be slowly cooled, led to the traction equipment and the shaping mold, and these equipment are started. Then, according to the indication of the control surface and the requirements for the extruded product, the various parts are adjusted accordingly to make the entire extrusion operation reach the normal state.
The twin-screw extruder adds satisfactory materials according to needs, and uses a metering feeder to feed evenly and at a constant speed.
When the mold discharges the material evenly and the glue is excellent, the shaping sleeve can be pulled. The degree of plasticization should be judged by experience. Generally, it can be judged based on the appearance of the extruded material, that is, the surface is glossy, free of impurities, no foaming, coking, and discoloration. Knead the extruded material by hand to a certain degree, without burrs and cracks, and with a certain elasticity. At this time, it shows that the material is well plasticized. If the plasticization is poor, the screw speed, barrel and die head temperature can be adjusted appropriately until the requirements are met.
3. Shutdown
Stop feeding and breaking the plastic in the machine. When the screw is exposed, turn off the power of the barrel and die, and stop heating.
Note: The installation and commissioning of the equipment are generally specified in the operating instructions. It is a prerequisite that the operator is familiar with the equipment he operates. For example, he should master the structural characteristics of the screw extruder, the characteristics of the heating and cooling control surfaces, the characteristics of the die and components, and then correctly master the extrusion process conditions and operate the machine correctly.
In addition, the following are matters needing attention during the operation of the plastic extruder:
1. Pay special attention to fire safety. Fire extinguishers should be placed near machines and equipment using heat transfer oil.
2. When abnormal or abnormal conditions occur, be sure to report to relevant staff, and the maintenance center staff will handle them. If any abnormal problems that endanger safety occur, press the emergency stop button immediately.
3. Do not use low-quality recycled materials with metal residues or fine sand. Metal objects that may fall in should not be placed near the feed port to prevent further damage to the extruder screw and barrel or jamming and damage.
4. During the operation of plastic machinery and equipment, gear oil with cleanliness, viscosity and other indexes that meet the requirements should be used, and sufficient cooling circulating water should be provided to the water cooler in accordance with the requirements to prevent hydraulic parts and pipelines from being blocked, leaking and other damage problems due to environmental pollution of the compressor lubricating oil or continuous high temperature. The extruder should add lubricating oil that meets the requirements to the reducer.
5. During the operation of plastic machinery and equipment, the operating procedures must be strictly followed, and no illegal behavior should be performed at non-operating stations. To ensure the reliability of safety devices, the safety protection measures of the equipment should not be destroyed in pursuit of efficiency.
6. During the operation of plastic machinery and equipment, if the material temperature does not reach the set temperature and the insulation space is insufficient, the extruder screw cannot be started.
7. The operation process shall be carried out by trained staff who are familiar with the structure, performance and operation process of plastic machinery and equipment.
When shutting down the plastic extruder, we also need to pay attention to many issues. Let's take a look together:
1. Turn off the feeding system and stop heating.
2. Try to squeeze out the plastic in the plastic extruder in the next operation.
3. After the material is basically drained, turn off the power of the main machine.
4. Turn off the power of each section heater and cooling water pump.
5. Close the water inlet valve.
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