Heating-and-melting unit is served with one operator.
Principle of operation.
Heating-and-melting unit is controlled by one control cabinet. Each screw is rotated by means of an individual drive unit. Prepared uniformly pre-mixed mixture of the polymeric components is supplied in the preheated working chamber of the heating-and-melting unit through the receiving hopper. Upper auxiliary screw prevents clogging of the receiving hopper with raw material by agitating the feed material thus facilitates delivery of raw materials to the main screw. The main lower screw rotates and provides stirring of the composite mixture and its motion within the working chamber with passing through six heating zones. Within the first two heating zones the mixture is heated and dried (residual moisture is removed), within the next two (medium) zones the polymers are plasticized and thereby a homogeneous composite mixture is obtained, within the final zones the mixture temperature is maintained and therefore its consistency required for its subsequent molding. Ready mixture is moved by the main screw to the outlet located in the output (front) housing flange. This opening is closed with gate valve, which is opened by moving the handle upwards. To lock in the closed position press on the handle downward until it stops. Finished mixture is weighed at the output by electronic scales, and then it is fed to the mold cavity to form the product.
Structural features of double-screw heating-and-melting unit
Use of double-screw vertical heating-and-melting unit provides the following benefits:
- Easy feeding of materials into the working chamber;
- More efficient stirring of raw materials and prevention of stoppers;
- Prevention of the feed hopper clogging;
- Self-cleaning of screw shafts (implemented by the significant overlap of the screw blades, wherein the blades of one screw move at extremely small distance from the shaft surface of the other screw, which allows the blades to remove raw materials accumulated on the shafts and thus to ensure uniform stirring throughout the mixture).
Usage of the working chamber housing with an oval cross-section allows you to:
- Effectively solve the problem of removal and discharge of vapors and gases, which naturally accumulate in the upper part and remove through the discharge openings thanks to this configuration;
- Eliminate probability of sticking the polymer mass on the inside wall of the working chamber due to the fact that the raw materials under the influence of gravity deposits at the bottom of the housing where it is stirred effectively.
Furthermore, the use of individual drive for each screw allows:
- To implement an independent asynchronous control of screw speed;
- To implement reverse flow on each of the screws.
Number of screws
Nominal power of main screw motor
Nominal power of auxiliary screw motor
Total rated power consumption of heating-and-melting unit, maximum
Number of heating elements
Nominal power consumption of heating elements, maximum
Total actual power consumption of electric motors (when entering the continuous working mode), maximum
Total actual power consumption of heating elements (when entering the continuous working mode), maximum
Main screw motor shaft speed
Auxiliary screw motor shaft speed
Main screw nominal speed at I motor speed equal to 25 Hz (when motor shaft speed equals 500 rpm)
Main screw nominal speed at II motor speed equal to 35 Hz (when motor shaft speed equals 700 rpm)
Main screw nominal speed at III motor speed equal to 45 Hz (when motor shaft speed equals 900 rpm)
Capacity (output of the finished product), maximum