Extruder operation and maintenance

The operator must be familiar with the extruder he operates, and must correctly grasp the characteristics of the screw, the control of heating and cooling, the characteristics of the instrument, the structure and assembly of the control mold of the traction machine, etc., so as to correctly grasp the extrusion process conditions and operate the machine correctly.

General steps for debugging

1. Before starting the machine, check whether the temperature control is sensitive, whether the instrument is out of order, whether the cooling channel is unblocked, etc. Usually the thermometer, cooling water and other methods are used for detection.

2. According to the extruder operation procedures, the screw, barrel and die head of the extruder are heated, and after the temperature rises to the set temperature, it must be kept warm for about 10 minutes before the machine can be started, so that the temperature of each part of the machine tends to be stable.

3. Before starting the machine, be sure to tighten the connecting screws and bolts of each part of the die while they are hot. Before the material is extruded, the operator must not stand in front of the die to prevent bolts or screws from breaking and causing injury accidents.

4. When starting extrusion, the screw speed should be slow, and then gradually increase to prevent overload and damage to the parts during starting.

5. When starting the machine, add a small amount of material first, and keep the feeding balance, pay close attention to various table values such as torque when feeding, and wait for the material to be extruded from the die head and pull on the traction equipment, so as to gradually increase the amount of material until normal extrusion.

6. When starting traction, there should be a certain distance between the shaping die and the die head to facilitate traction. Open the waterway (note that water should not be poured on the die, otherwise it will cause the discharging of the die head to be abnormal and lead to material breakage or mold plugging), the shape is complex, the cavity is small and the cover plate of the mold needs to be opened for multi-cavity profiles; After confirming that the plasticization of the extruded material is normal, the material is pulled to the tractor through the set towing rope. Shorten the distance between the setting table and the die head, cover the cover plate, start the vacuum pump, and when the extrusion speed and the traction speed are basically balanced, observe the profile to normal extrusion and then shrink the distance between the setting table and the die head to the ideal value.

7. If it is found that the parison is not formed at the inlet end of the shaping die or the inner rib adheres to the inner cavity surface of the profile, a pointed tool can be used to poke several small holes in the unformed part of the parison or the inner rib part of the inlet end of the first section of the shaping die, so that the small cavity is connected with the atmosphere, and the parison is open when it enters the setting die, which is convenient for the formation of negative pressure and promotes the parison to be closely attached to the mold wall of the shaping die.

8. In case of mold plugging (not blocked), the setting table should be moved back or the traction speed should be increased immediately, or the above two schemes should be implemented at the same time, and then the normal production should be resumed through process adjustment. If the implementation of the above scheme has been blocked, the setting table should be moved back immediately, and the material should be shoveled along the shaping mold, the water vapor of the shaping die should be closed, the traction speed should be reduced, and the profile should be slowly pulled out from the shaping mold. If part of the profile is broken in the setting die, it is necessary to disassemble the setting die and completely remove the remaining material.

9. When the machine is stopped, it is generally necessary to add the stop material to squeeze out the production material in the machine, and then stop the machine and disassemble the die head while it is hot for mold cleaning.