Each type of product in the plastic extrusion production line has its operating characteristics. Only by having a detailed understanding of its operating characteristics can the efficiency of the machine be fully played. Extruder is one of the types and its, grasp the operation points of extruder, correct and reasonable use of extruder. The use of screw extruder includes the installation, adjustment, commissioning, operation, maintenance and repair of the machine and a series of links, its use has the common characteristics of general machines, mainly in the driving motor and deceleration gear. But the working system of screw extruder is extrusion system, but it has its own characteristics, special attention should be paid to its characteristics when using screw extruder.

The installation, adjustment and commissioning of the machine are generally specified in the operation manual of the extruder. Here, the operation points, maintenance and maintenance of the extruder are described as follows:

Operators must be familiar with their own operation of the extruder structural characteristics, especially to correctly grasp the screw structural characteristics, heating and cooling control instrument characteristics, head characteristics and assembly conditions, in order to correctly grasp the extrusion process conditions, the correct operation of the machine.

When making different plastic products, the operation points of the extruder are different, but they also have their similarities. The following brief introduction of various products when the same operation steps and attention should be paid to extruder operation points.

1. Preparation before driving

(1) Plastics used for extrusion molding. Raw materials shall meet the required drying requirements, further drying if necessary. The material is sifted to remove clumps and mechanical impurities.

(2) Check whether the water, electricity and gas systems in the equipment are normal to ensure that the water and gas channels are smooth and leak-free, whether the electrical system is normal, and whether the heating system, temperature control and various instruments are reliable; Auxiliary engine empty low speed test run, observe whether the equipment is running normally; Start the vacuum pump of the setting table and observe whether the work is normal; Lubricate the smooth parts of various equipment. If a fault is found, remove it in time.

(3) installing head and setting sleeve. According to the product variety, size, select the head specification. Assemble the nose in the following order.

2. Driving

(1) The machine can be started after constant temperature. Before starting the machine, the flange bolts of the machine head and extruder should be tightened again to eliminate the difference between the thermal expansion of the bolts and the machine head. The sequence of tightening the bolts of the machine head is diagonal tightening, and the force should be uniform. When tightening the flange nut of the machine head, the tightness around is required to be consistent, otherwise the material should be run.

(2) To start a car, choose to press the "ready to start" button, then connect the "start" button, and then slowly rotate the screw speed adjustment knob, screw speed slow start. Then gradually speed up, at the same time a small amount of feeding. When feeding, we should pay close attention to the host ammeter and various indication table head indication change. Screw torque cannot exceed the red label (generally 65%-75% torque table). Before the plastic profile is extruded, no one is allowed to stand in front of the mouth die, in order to prevent injury accidents caused by bolt breakage or wet bubble release of raw materials. After the plastic is extruded from the die of the nose, it is necessary to slowly cool the extrude and pull the traction device and the mold, and start these devices. Then according to the indicated value of the control instrument and the requirements of the extruded products. Each part is adjusted accordingly to make the whole extrusion operation reach the normal state. And according to the need to add sufficient material, double screw extruder using metering feeder uniform speed feeding.

(3) when the mouth die discharge is uniform and the plastic is good, the traction can be fixed. 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 is glossy, no impurities, no foaming, coke and discoloration. By hand, the extruded material is squeezed fine to a certain extent without burrs and cracks, and there is a certain elasticity. If the plasticization is bad, the screw speed, barrel and head temperature can be properly adjusted until the requirements are met.

(4) In the extrusion production process, it shall check regularly 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 quality inspection standards, and take measures to solve problems in time.

3. Parking

(1) Stop feeding, squeeze out the plastic in the extruder, and turn off the power supply of the barrel and the head to stop heating when the screw is exposed.

(2) Turn off the power supply of extruder and auxiliary machine, so that the screw and auxiliary machine stop running.

(3) Open the connecting flange of the head and remove the head. Clean the perforated plate and all parts of the machine head. In order to prevent damage to the inner surface of the head, the residual material in the head should be cleaned by steel law and steel sheet, and then the plastic adhering to the head should be ground with sandpaper, and polished, and coated with oil or silicone oil to prevent rust.

(4) Cleaning of screw and barrel. After removing the head, restart the main engine, add stopping material (or crushing material), clean the screw and barrel. At this time, the screw is selected at a low speed (about sr/min) to reduce wear. After the stopping material is pulverized and completely extruded, the residual particle and powder can be blown out repeatedly by compressed air from the feeding port and exhaust port until there is no residual material in the barrel. Then, the screw speed is reduced to zero, the extruder is stopped, and the main power supply and cold water valve are closed.

(5) The extruder should pay attention to the safety items in the extrusion: electricity, heat, mechanical rotation and heavy parts of the loading and unloading. Extruder locomotive room must be equipped with lifting equipment, install and disassemble the head, screw and other heavy parts, to ensure the safety of production.