Views: 96 Author: Site Editor Publish Time: 2021-02-22 Origin: Site
The laboratory extruder extrusion system includes screw, barrel, hopper, head, and die. The plastic is plasticized into a uniform melt through the extrusion system and is continuously extruded by the screw in the process.
Extruder screw is the most important part of the lab scale twin screw extruder. It is directly related to the application range and productivity of the extruder. It is made of high-strength corrosion-resistant alloy steel.
It is a metal cylinder, generally made of alloy steel that is heat-resistant, high-pressure-resistant, strong, wear-resistant, and corrosion-resistant. The extruder barrel and the screw are matched to crush, soften, melt, plasticize, exhaust, and compact the plastic, and continuously and uniformly deliver the plastic to the molding system. Generally, the length of the barrel is 15-30 times its diameter, so that the plastic is fully heated and plasticized as a principle.
The bottom of the hopper is equipped with a cutting device to adjust and cut off the material flow. The side of the hopper is equipped with a sight hole and a calibration metering device.
The machine head is composed of an alloy steel inner sleeve and a carbon steel outer sleeve, and a forming mold is installed in the machine head. The function of the machine head is to transform the rotating plastic melt into parallel linear motion and introduce it into the mold sleeve evenly and smoothly.
The plastic is plasticized and compacted in the barrel and flows into the molding die through the porous filter plate along the flow channel through the head and neck to form an annular gap with a decreasing cross-section so that the plastic melt forms a dense tubular coating around the core wire. To ensure that the plastic flow path in the machine head is reasonable and eliminate the dead angle of accumulated plastic, the general machine will be equipped with a shunt sleeve. To eliminate pressure fluctuations during plastic extrusion, a pressure-equalizing ring is also set. The lab scale twin screw extruder head is also equipped with a mold correction and adjustment device, which is convenient to adjust and correct the concentricity of the mold core and the mold sleeve.
Inspect each lubrication part at least 1 to 2 times per shift, add enough lubricating oil, and the temperature of the bearing part should not exceed 50℃ when working.
Before feeding production, the barrel and forming mold must have a certain heating and constant temperature time, and feeding production under the condition of lower than the plasticization temperature of the raw materials is not allowed.
The extruder screw must be started at a low speed, and the screw speed is allowed to gradually increase only after a period of operation at a low speed.
The idle running time of the screw in the barrel is not allowed to exceed 2 to 3 minutes, to avoid the screw and barrel from rolling.
The current change of the main motor should be observed frequently during the working of the laboratory twin screw extruder. When the motor is found to work under overload conditions for a long time (the instant overload is allowed), it should be stopped immediately. Wait for the staff to find the cause of the failure and continue production after the failure is eliminated.
After the barrel is heated to a constant temperature for the first time, tighten the fixing screw connecting the barrel and the base again.
Before installing the screw and the mold, clean the mating contact surfaces of the parts, and apply a layer of molybdenum disulfide or silicone oil to the fastening bolts to facilitate the disassembly of the parts at high temperatures. When disassembling each part, do not use a heavy hammer to hit the working surface of each part. If necessary, pad hardwood and hammer the hardwood to remove the parts.
When removing the residual material on the barrel, screw, and mold, only use a bamboo or copper knife to scrape the sticky material. It is not allowed to scrape the sticky material with a steel knife, and it is not allowed to remove the residual material on the screw by using the fire barbecue method.
Regular maintenance is usually carried out after the lab scale extruder has been running continuously for 2500-5000h and then the machine is shut down. The machine needs to be disassembled to inspect, measure, and appraise the wear of main parts, replace parts that have reached the prescribed wear limit, and repair damaged parts.
When conditions permit, it is best to appoint a person to be responsible for equipment maintenance. And each maintenance and repair situation is included in the factory equipment management file.
Do you now know the extrusion system of the laboratory extruder? Chuangbo is a professional twin screw extruder manufacturer and supplier in China. We can provide customers with different extruders with excellent performance, such as masterbatch extruder, PVC compounding, thermoplastic elastermor, reaction extrusion line, devolatilization extruder, pelletizing system, etc.