It is easier to clean the carbide in the extruder by the in-machine cleaning method, but it is difficult to clean the carbide in the storage head of Shanghai blow molding equipment.

Because the internal structure of the extruder is simpler, the internal structure of the storage head of Shanghai blow molding equipment is complex, and the equipment has been used for too long, it will be more difficult to clean.

 

In this case, disassembly and cleaning are imperative. After heating the machine head to a high temperature, turn off the power supply and disassemble all the assembly parts of the machine head. Use a copper sheet to clean the plastic melt in the machine head, use a metal brush to remove the burnt carbide, and then use sandpaper or a flower impeller to polish and clean each assembly before assembling. Although the disassembly and cleaning effect is very good, it takes a long time and is laborious, so this disassembly and cleaning method is generally not used easily.

 

3. Preventive measures for carbonization

3.1 Temperature and time control

The processing temperature of Shanghai blow molding products is determined according to the plasticization requirements of raw materials and products, and cannot be too high or too low. Too low temperature will lead to excessive load, and defects such as water marks and weld marks on the product appearance will appear.

If the temperature is too low, the fluidity of the melt will be poor, and it will also have a great impact on the glossiness of the product surface and the filling of the corners; if the temperature is too high, and sometimes the machine is temporarily shut down for two hours or even several hours, it is easy to cause carbonization of the melt in the machine. In this case, the constant temperature is between 100 and 120℃, and it is necessary to heat it to the required temperature before starting the machine, so as to prevent carbonization caused by a sudden increase in temperature or a long shutdown and insulation time.

 

3.2 Heating and startup operation control 

The one-step heating method is usually adopted, that is, after setting the temperature, it is continuously heated to the set temperature, and the temperature is kept constant for 1 to 3 hours before starting the machine according to the size of the equipment. This method easily causes carbonization of the residual plastic in the machine.

If the step heating method is adopted, the temperature is increased in time periods, and the effect is much better. For example: the temperature is set to 100℃ at the beginning, and the temperature is set to 130℃ after constant temperature, and then the temperature is set to 170℃ after constant temperature, and the temperature is gradually increased according to the time period until the required temperature is reached. Small and medium-sized equipment can be turned on when the required temperature is reached. Of course, relevant supporting preparations need to be made in advance. After large equipment reaches the required temperature, it is better to keep the temperature constant for 1 to 2 hours before starting.

When just starting the machine, it is necessary to pay attention to the speed of the extruder to slowly accelerate from 1 to 5 rpm, the feed port is slowly opened, and the current value displayed on the extrusion ammeter is always paid attention to. If the load is too large, the constant temperature time should be appropriately extended to achieve step-by-step temperature increase. When it can be turned on, it should be turned on as soon as possible to prevent the residual plastic in the machine from carbonizing during the long waiting time for starting when it suddenly encounters high temperature.