Each type of product in the plastic extrusion line has its operating characteristics. Only with a detailed understanding of its operating characteristics can the efficiency of the machine be given full play. Extruder is one of the types, grasp the key points of extruder operation, the correct and reasonable use of an extruder. The use of the screw extruder includes the installation, adjustment, commissioning, operation, maintenance and repair of the machine and a series of links, its use has the general characteristics of the machine, mainly in the drive motor and speed reducer. However, the working system of the screw extruder is the extruder system, and it has unique characteristics.
The installation, adjustment and test run of the machine are generally specified in the operating manual of the extruder. The operation points of the extruder, maintenance and maintenance are described as follows:
Operators must be familiar with the structural characteristics of the extruder they operate, especially to correctly grasp the screw structure characteristics, heating and cooling control instrument characteristics, nose characteristics and assembly, so as to correctly grasp the extrusion process conditions, correctly operate the machine.
When making different plastic products, the operating points of the extruder are different, but there are some similarities. The following is a brief introduction of the same procedure and the key points of the extruder.
Used for extrusion molding of plastics. The raw materials shall meet the required drying requirements and shall be further dried if necessary. Sift the raw material to remove caked aggregates and mechanical impurities.
Check whether the water, electricity and gas systems in the equipment are normal, ensure that the water and gas paths are smooth and no leakage, whether the electrical system is normal, whether the heating system, temperature control and various instruments work reliably; Auxiliary engine empty car low-speed test run, observe whether the equipment operates normally; Start the vacuum pump of the shaping table and observe whether the work is normal. Lubricate the smooth parts of various equipment. If the fault is found, remove it in time.
Mounting head and shaping set.
According to the product variety, size, choose the machine head specifications. Install the nose in the following order.
The machine head and the flange bolts of the extruder should be tightened again before starting the machine head at a constant temperature to eliminate the difference between the bolts and the head's thermal expansion. The bolts of the tightening head should be tightened diagonally in order and the force should be uniform. When tightening the flange nut of the machine head, the requirement is consistent with the tightness around, otherwise, the material will be run.
The startup, select and press the "prepare to start up" button, then connect the "start-up" button, then slowly rotate the screw speed adjusting knob, the screw speed starts slowly. Then gradually speed up, while adding a small amount of material. When feeding should pay close attention to the host ammeter and various indicator head indicator changes. Screw torque cannot exceed the red label (generally 65-75% of the torque table). Before the plastic profile is extruded, any person shall not stand in front of the die, in order to prevent damage accidents caused by bolt breaking or wet release of raw materials. After the plastic is extruded from the die, the extruder is cooled slowly and the drawing device and the shaping die are put into operation. Then according to the indication value of the control instrument and the requirements of the extruded products. Adjust each part accordingly to make the whole extrusion operation reach the normal state. And according to the need to add enough material, double screw extruder adopts metering feeder feeding uniform speed.
When the die out evenly and good plastic can be used to shape the traction. The judgment of the degree of plasticization needs experience, generally can be judged according to the appearance of extruded materials, that is, the surface is shiny, no impurities, no foam, coke and discoloration, squeeze the extruder by hand to a certain degree of no burr, crack, a certain degree of elasticity, this means that the material plasticization is good. If the plasticization is not good, the screw speed, barrel and nose temperature can be adjusted until the requirements.
In the process of extrusion production, check whether various process parameters are normal regularly according to the process requirements, and fill in the process record sheet. Inspect the quality of profile products according to quality inspection standards, and take measures to solve problems.
Stop feeding and squeeze out the plastic in the extruder. When the screw is exposed, turn off the power supply of the barrel and the head and stop heating.
Turn off the power of the extruder and auxiliary machine, and stop the operation of the screw and auxiliary machine.
Open the connection flange of the machine head and remove the machine head. Clean up the perforated plate and various parts of the machine head. In order to prevent damage to the inner surface of the machine head, the residual materials in the machine head should be cleaned with steel law and steel sheet, and then the plastic adhering to the machine head should be removed with sandpaper, and polished, coated with oil or silicone oil to prevent rust.
Clean the screw rod and barrel. After removing the head, restart the main machine, add parking materials (or broken materials), and clean the screw rod and barrel. After the stop material is crushed into powder and completely extruded, compressed air can be used to repeatedly blow out residual particles and powder from the feeding port and exhaust port until there is no residual material in the barrel. Then, the screw speed should be reduced to zero, the extruder should be stopped, and the main power and cold water valve should be closed.
The safety items that the extruder should pay attention to during extrusion include: electricity, heat, mechanical rotation and the loading and unloading of heavy parts. The extruder must be equipped with lifting equipment, and the machine head, screw and other heavy parts should be installed and removed to ensure safe production.
KEYA Twin Screw Extruder