The extruder is the most basic equipment for wire and cable insulation and sheath extrusion. The functional characteristics of the extruder determine its important position in the wire and cable processing equipment. Correct and reasonable use of the extruder can give full play to the efficiency of the machine, maintain a good working condition and prolong the service life of the machine.
The use of extruder includes a series of links such as installation, adjustment, commissioning, operation, maintenance and repair of the machine.
The installation, commissioning and trial run of the machine are generally correctly specified in the operating instructions. LINT TOP will make an introduction to the operation and maintenance of the machine.
1.How to operate the extruder
The operator must be familiar with the structural characteristics of the extruder, especially the characteristics of the screw, heating and cooling control instruments, head and the assembly conditions, etc., in order to correctly grasp the extrusion process conditions, correct operate the machine.
The operation methods for extruding different plastic products are different, but there are also similarities. The following is a brief introduction to the same operation steps and precautions when extruding various products.
(1)Preparations before starting
a. For the plastics used for extrusion molding, the raw materials should meet the required drying requirements.
b. Check whether the water, electricity and gas systems in the equipment are normal. Test auxiliary machine without load at low speed to observe whether the equipment is running normally. Start the vacuum pump of the setting table to observe whether the work is normal. Add oil to the lubrication parts of various equipment. If a fault is found, remove it in time.
c. Install the machine head and the setting sleeve. According to the variety and size of the product, select the head specification.
(2)Starting
a. You can start the machine after reaching constant temperature. Before starting, the bolts of the machine head and the extruder flange should be tightened again to eliminate the difference in thermal expansion between the bolts and the machine head. The order of tightening the machine head bolts is to tighten diagonally, and the force should be even.
b. For drive, select and press the "ready to start" button, then press the "start" button, then slowly rotate the screw speed adjustment knob, and the screw speed starts slowly. Then gradually increase the speed, adding small amounts of plastic material at the same time. When feeding, pay close attention to the indication changes of the host ammeter and various indicating heads.
c. When the discharge is uniform and the plasticization is good, the traction can be carried out. Judging the degree of plasticization depends on experience. Generally, it can be judged according to the appearance of the extruded material, that is, the surface is shiny, free of impurities, no foaming, coke and discoloration, There are no burrs, cracks, and a certain elasticity when the extruded material is squeezed by hand to a certain extent, which means that the material is well plasticized. If the plasticization is poor, the screw speed, barrel and head temperature can be adjusted appropriately until the requirements are met.
d. During the extrusion production process, regularly check whether various process parameters are normal according to the process requirements, and fill in the process record sheet.
(3)Parking
a.Stop feeding and squeeze out the plastic in the extruder. When the screw is exposed, turn off the power of the barrel and the head, and stop heating.
b. Turn off the power supply of the extruder and auxiliary machine, and stop the screw and auxiliary machine from running.
c. Open the connection flange of the machine head and disassemble the machine head. Clean the perforated plate and various parts of the handpiece.
d. After removing the machine head, restart the main machine, add parking material (or crushed material), and clean the screw and barrel. After the stopped material is crushed into powder and completely extruded, compressed air can be used to repeatedly blow out residual pellets and powder from the feeding port and the exhaust port until there is no residual material in the barrel, then reduce the screw speed to zero and stop the extrusion. machine, turn off the main power supply and the cold water main valve.
2.How to maintain the extruder
The screw extrusion system is maintained in two ways: daily maintenance and regular maintenance.
a. Routine maintenance is a regular routine work, which does not occupy the operating hours of the equipment, and is usually completed during driving. The key is to clean the machine, lubricate the moving parts, tighten the loose threaded parts, check and adjust the motor, control instruments, working parts and pipelines in time.
b. Regular maintenance is generally carried out after the extruder runs continuously for 2500-5000 hours. The machine needs to be disassembled to check, measure and identify the wear of main parts, replace the parts that have reached the specified wear limit, and repair the damaged parts.
c. It is not allowed to run empty, so as to avoid the screw and the machine from rolling.
d. If abnormal sound occurs during the operation of the extruder, it should be stopped immediately for inspection or repair.
e. Strictly prevent metal or other sundries from falling into the hopper, so as not to damage the screw and barrel.
f. Pay attention to the cleanliness of the production environment, and do not allow impurities to be mixed into the material to block the filter plate, which will affect the output and quality of the product and increase the resistance of the machine head.
g. When the extruder needs to be stopped for a long time, anti-rust grease should be applied to the working surfaces of the screw, machine, and head.
h. Regularly calibrate the temperature control instrument to check the correctness of its adjustment and the sensitivity of the control.
i. The maintenance of the reducer of the extruder is the same as that of the general standard reducer. It is mainly to check the wear and failure of gears, bearings, etc.
j. The inner wall of the cooling water pipe attached to the extruder is easy to scale and the outside is easy to corrode and rust. Careful inspection should be done during maintenance. Excessive scale will block the pipeline, and the cooling effect will not be achieved. If the rust is serious, water will leak. Therefore, scale removal and anti-corrosion cooling measures must be taken during maintenance.
k. For the DC motor that drives the screw to rotate, it is necessary to focus on checking the wear and contact of the brushes. It should also be frequently measured whether the insulation resistance value of the motor is above the specified value.
l. Designate a person to be responsible for equipment maintenance. And the detailed records of each maintenance and repair are listed in the factory equipment management file.