When making different plastic products, the operating points of the extruder are different, but there are similarities. The following is a brief description of the same procedure for extruding various products and the operating points of the extruder that should be noted.

1. Preparation before driving

(1) Plastics for extrusion molding. The raw materials should meet the required drying requirements and further drying if necessary. The raw materials are sieved to remove agglomerates and mechanical impurities.

(2) Check whether the water, electricity and gas systems in the equipment are normal, ensure that the water and gas lines are unblocked, not leaking, whether the electrical system is normal, the heating system, temperature control, and various instruments are reliable; the auxiliary machine is running at low speed. Observe whether the equipment is running normally; start the vacuum pump of the setting table to observe whether the work is normal; lubricate the lubrication parts of various equipment. If the fault is found to be eliminated in time.

(3) Install the machine head and set the sleeve. According to the variety and size of the product, choose the specifications of the machine head. Install the machine head in the following order.

2, driving

(1) After the constant temperature, the car and the extruder flange bolts should be tightened once again to eliminate the difference between the bolt and the thermal expansion of the machine head. The order of the tightening head bolts is diagonally tightened and the force should be even. When tightening the flange nut of the head, it is required to have the same tightness around the circumference, otherwise it is necessary to run the material.

(2) To drive, first press the “Ready to drive” button, then the “Drive” button, then slowly rotate the screw speed adjustment knob, and the screw speed starts slowly. Then gradually increase, while feeding a small amount. Pay close attention to the change of the indicator of the main current meter and various indicator heads when feeding. The screw torque cannot exceed the red mark (generally 65%~75% of the torque table). Before the plastic profile is extruded, no one should stand in front of the die to prevent injury due to bolt breakage or wet foaming of raw materials. After the plastic is extruded from the die, the extrudate is slowly cooled and introduced into the traction device and the sizing die, and the devices are activated. Then according to the indication value of the control instrument (see the figure below) and the requirements for the extruded product. The parts are adjusted accordingly to bring the entire extrusion operation to a normal state. And according to the need to add sufficient material, the twin-screw extruder uses a metering feeder to feed evenly and at equal speed.

(3) When the die is discharged uniformly and plasticized, the manding sleeve can be pulled. Judging the degree of plasticization depends on experience, generally can be judged according to the appearance of the extruded material, that is, the surface is shiny, no impurities, no foaming, coke and discoloration, and the extruded material is squeezed to a certain extent by hand. The burrs and cracks have a certain elasticity. At this time, the material is plasticized. If the plasticization is poor, the screw speed, barrel and head temperature can be adjusted appropriately until the requirements are met.

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

3. Parking

(1) Stop feeding, squeeze the plastic in the extruder to expose the screw, turn off the power of the barrel and the head, and stop heating.

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

(3) Open the head coupling flange and disassemble the machine head. Clean the perforated plate and the various parts of the machine head. In order to prevent damage to the inner surface of the machine head, the residual material in the machine head should be cleaned by steel law and steel sheet, then the plastic adhered to the machine head should be removed by sandpaper and lighted, coated with oil or silicone oil. rust.

(4) Clean the screw and barrel. After removing the machine head, restart the main machine, add parking material (or broken material), clean the screw and barrel. At this time, the screw is selected at low speed (sr/min) to reduce wear. After the material to be stopped is crushed into powder and completely extruded, the residual pellets and powder can be repeatedly blown out from the feeding port and the exhaust port by compressed air until the barrel has no residual material, and the screw speed is reduced to zero to stop the extrusion. Machine, turn off the main power and cold water main valve.

(5) Safety items that should be paid attention to during extrusion of the extruder include: electric, thermal, mechanical rotation and loading and unloading of bulky parts. The extruder workshop must be equipped with lifting equipment, detachable parts such as machine heads and screws to ensure safe production.

maintenance

The screw extrusion system is maintained in two ways: daily maintenance and regular maintenance:

(1) Routine maintenance is a routine routine, does not account for equipment operation hours, and is usually completed during driving. The focus is on cleaning the machine, lubricating the moving parts, tightening the loose threaded parts, checking and adjusting the motor in time, controlling the instrument, working parts and piping, etc.

(2) Regular maintenance is generally carried out after the continuous operation of the extruder is 2500-5000h. The machine needs to be dismantled, measured, and identified for the wear of the main parts, replace the parts that have reached the specified wear limit, and repair the damaged parts.

(3) Do not allow empty cars to run, so as to avoid screwing of the screw and barrel.

(4) If an abnormal sound occurs during the operation of the extruder, stop immediately and inspect or repair.

(5) Strictly prevent metal or other debris from falling into the hopper to avoid damage to the screw and barrel. In order to prevent iron debris from entering the barrel, a magnetically absorbing part or a magnetic frame may be placed at the feeding port of the material to prevent the impurities from falling into the material.

(6) Pay attention to the clean production environment, do not let the garbage impurities mix into the material to block the filter plate, affect the product output, quality and increase the resistance of the machine head.

(7) When the extruder needs to be stopped for a long time, it should be coated with anti-rust grease on the working surface of screw, barrel and head. The small screw should be hung in the air or placed in a special wooden box and leveled with wooden blocks to avoid deformation or bumping of the screw.

(8) Regularly calibrate the temperature control instrument to check the correctness of the adjustment and the sensitivity of the control.

(9) The gearbox maintenance of the extruder is the same as that of the general standard reducer. Mainly to check the wear and failure of gears, bearings and so on. The gearbox should use the lubricating oil specified in the machine manual, and add the oil according to the specified oil level. The oil is too small, the lubrication is insufficient, and the service life of the parts is reduced. The oil is too much, the heat is large, the energy consumption is high, and the oil is easy to deteriorate. Also, the lubrication is invalidated, resulting in damage to the parts. The oil leakage part of the gearbox should be replaced in time to ensure the amount of lubricant.

(10) The inner wall of the cooling water pipe attached to the extruder is easy to scale and the outside is easily corroded and rusted. Care should be taken during maintenance. Excessive scale will block the pipeline and will not reach the cooling effect. If the corrosion is serious, water leakage will occur. Therefore, descaling and anti-corrosion and cooling measures must be taken during maintenance.

(11) For the DC motor that drives the screw to rotate, it is important to check the brush wear and contact. The insulation resistance of the motor should be measured frequently. In addition, check the connection wires and other components for rust and take protective measures.

(12) Designate a person to be responsible for equipment maintenance. And record the detailed records of each maintenance and repair in the factory equipment

Dongguan Pinyang Cable Machinery Co., Ltd. is a professional manufacturer of wire and cable equipment for professional development, design and production. It specializes in: optical fiber extruder, ultra-fine winding machine, earphone wire special machinery and other products, optical fiber extruder, very fine winding Machine, earphone line dedicated mechanical consultation hotline: 13731224526 / Lu Jianjun