The operating skill of the extruder(2)

2. Drive of the extruder
(1)(extruder) start up after constant temperature. Before starting up, tighten the head and extruder flange bolts again to eliminate the difference between the bolts and the head thermal expansion. Tighten the head bolts diagonally and evenly. When tightening the flange nut of the machine head, it is required to have the same tightness around, otherwise the material will run off.

(2)(extruder) When starting, first press the "ready to start" button, then connect the "start" button, and then slowly rotate the screw speed adjustment knob to start the screw speed slowly. Then gradually speed up and add a small amount of material at the same time. During feeding, pay close attention to the indication changes of the host ammeter and various indicator heads. The screw torque shall not exceed the red mark (generally 65% ~ 75% of the torque table). Before the plastic profile is extruded, no one shall stand in front of the die to prevent injury accidents due to bolt breakage or wet foaming of raw materials. After the plastic is extruded from the die, it is necessary to slowly cool the extrudate, lead it to the traction device and setting die, and start these devices. Then according to the control instrument (see Fig. 1) and the requirements for extruded products. Each part shall be adjusted accordingly to make the whole extrusion operation reach the normal state. Sufficient material shall be added as required. The twin-screw extruder adopts a metering feeder to feed evenly and at the same speed.

(3) When the die discharge is uniform and the plasticization is good, the setting sleeve can be pulled. The degree of plasticization should be judged by experience. Generally, it can be judged according to the appearance of the extruded material, that is, the surface has luster, no impurities, no foaming, coke and discoloration. Squeeze the extruded material by hand to a certain extent, without burrs and cracks, and has a certain elasticity. At this time, it indicates that the plasticization of the material is good. If the plasticization is poor, the screw speed, barrel and head temperature can be adjusted appropriately until the requirements are met.

(4) in the process of extrusion production, regularly check whether various process parameters are normal according to the process requirements, and fill in the process record sheet. Check the quality of profile products according to the quality inspection standards, and take measures to solve problems in time.

3. Parking(extruder)
(1) stop feeding and extrude all the plastics in the extruder. When the screw is exposed, turn off the power supply of the barrel and head and stop heating.

(2) turn off the power supply of extruder and auxiliary machine to stop the screw and auxiliary machine.

(3) open the connecting flange of the machine head and disassemble the machine head. Clean the perforated plate and all parts of the machine head. During cleaning, in order to prevent damage to the inner surface of the machine head, the residual materials in the machine head shall be cleaned with steel law and steel sheet, and then the plastic adhered to the machine head shall be ground off with sandpaper, polished, and coated with engine oil or silicone oil for rust prevention.

(4) clean the screw and barrel. After removing the head, restart the host, Add stop material (or broken material), and clean the screw and barrel. At this time, the screw adopts low speed (about Sr / min) to reduce wear. After the shutdown material is milled into powder and completely extruded, the residual particles and powder can be blown out repeatedly from the feeding port and exhaust port with compressed air until there is no residual material in the barrel, reduce the screw speed to zero, stop the extruder, and close the main power supply and cold water main valve.

(5) safety items to be paid attention to during extrusion of extruder include: electrical, thermal and mechanical rotation, loading and unloading of heavy parts, etc. The extrusion locomotive room must be equipped with lifting equipment to assemble and disassemble heavy parts such as machine head and screw to ensure safe production.