How to maintain screw extruder?

Screw extruder maintenance process is generally divided into daily maintenance and regular maintenance

Daily maintenance: regular routine work, does not occupy the equipment operation man hour, usually completes during the start-up. The key point is to clean the machine, lubricate the moving parts, fasten the loose threaded parts, check and adjust the motor, control instrument, working parts and pipelines in time.

Regular maintenance: generally, the extruder is shut down after 2500-5000h continuous operation. The machine needs to be disassembled to check, measure and identify the wear condition of main parts, replace the parts that have reached the specified wear limit, and repair the damaged parts.

The two maintenance processes complement each other and are indispensable. Here is a brief introduction to the details of daily maintenance:

Daily maintenance

As the electrical control system has high requirements for environmental temperature and dust prevention, the electrical system should be separated from the production site, and ventilation or ventilator should be installed. It is suggested that the electric control cabinet should be placed in a simple room to keep the room clean and ventilated, so that the indoor temperature is not higher than 40 ℃.

The extruder is not allowed to run empty to avoid roughing of screw and barrel. When the main engine starts idling, it is not allowed to exceed 100r / min; when starting the main engine, slow down first, check whether there is abnormal sound after starting the main engine, and then slowly increase the speed of the main engine to the allowable range of the process (it is better to adjust to the best state). When the new machine is running in, the current load should be 60-70%, and the current in normal use should not exceed 90%. Note: in case of abnormal sound during the operation of extruder, stop immediately for inspection or repair.

The oil pump shall be turned on before starting the machine and turned off after shutting down; the water pump shall be kept in working condition during the whole production process, and the operation of the water pump shall not be stopped, so as to avoid the decomposition and carbonization of materials in the barrel due to the rise of barrel temperature; the asbestos hood of the main motor fan shall be cleaned frequently, so as to avoid too much dust sticking to block the hood, resulting in insufficient heat dissipation of the motor and tripping due to overheating.

Clean the dirt, tools and sundries on the surface of the unit in time.

Strictly prevent metal or other sundries from falling into the hopper, so as not to damage the screw and barrel. In order to prevent the iron impurities from entering the barrel, magnetic absorbing parts or magnetic frame can be installed at the feeding port of the barrel to prevent the impurities from falling into the barrel. The materials must be screened in advance.

Pay attention to the clean production environment, do not make the waste impurities mixed into the material to block the filter plate, affect the product output, quality and increase the resistance of the machine head.

The gearbox should use the lubricating oil specified in the machine manual, and add the oil according to the specified oil level height. If the oil level is too low, the lubrication is not enough, and the service life of the parts will be reduced. If the oil level is too high, the heating is too high, the energy consumption is too high, and the oil is easy to deteriorate, the lubrication will also fail, causing damage to the parts. The sealing gasket (ring) should be replaced in time at the oil leakage part of the reducer to ensure the amount of lubricating oil.

Regular maintenance

Regularly check whether the screws and other fasteners on the surface of the unit are loose and properly tightened in time. The lubricating oil level of the transmission box should be added or replaced in time (the dirt at the bottom of the oil tank should be cleaned regularly). For new machines, the oil should be changed every three months, and then every six months to a year. The oil filter and oil suction pipe should be cleaned regularly (once a month).

The maintenance of extruder reducer is the same as that of general standard reducer. It is mainly to check the wear and failure of gears and bearings.

When re installing, please pay attention to the original position of screw a and B, which can not be replaced! After the new screw is installed on the machine, you must turn it by hand first. If it turns normally, you can start the machine at low speed. When the screw ring barrel is not used for a long time, anti rust and anti fouling measures should be taken, and the screw should be suspended. If the thread block is burned, the flame should move left and right, and clean while burning. Don't burn too much (the blue ring turns red), and don't put the screw block into the water.

Regular calibration of temperature control instruments, check the correctness of its regulation and control sensitivity.

Distilled water must be used in the cooling water tank in the barrel to prevent the formation of scale and block the cooling channel in the barrel, resulting in temperature failure. Pay attention to add water properly in use to prevent scaling. If it is blocked, the cylinder should be replaced for specific maintenance. If there is no blockage and the water output is small, it indicates that there is scale. The water in the water tank should be replaced with dilute hydrochloric acid for circulation, and the distilled water should be replaced after the scale is cleared to normal. Generally, the water in the water tank is used to cool the barrel, while the natural water we use is used to cool the water tank. Regularly check the water quality of the cooling water tank, if there is turbidity, it should be replaced in time.

Check whether the solenoid valve works normally and whether the coil is burnt out. If so, replace it in time.

The possible reasons for the temperature not rising and falling are as follows: whether the thermocouple is loose; whether the relay in the heating area works normally; whether the solenoid valve works normally; timely replace the deformed heater and tighten the screw.

Timely clean up the dirt in the vacuum tank and the materials in the exhaust chamber to make the pipeline smooth. If the seal ring of the vacuum pump is worn, it needs to be replaced in time and checked regularly. The output shaft runout must be caused by bearing damage and shaft fracture. It must be replaced out of the box. If the bearing positions of the two output shafts of the gearbox are worn too seriously, the box must be replaced to avoid greater failure loss.

For the DC motor driving screw rotation, it is necessary to focus on the inspection of brush wear and contact, and it is also necessary to frequently measure whether the insulation resistance value of the motor is above the specified value. In addition, check whether the connecting wire and other parts are rusty, and take protective measures.

When the extruder needs to be out of service for a long time, antirust grease should be applied on the working surface of screw, barrel and head. The small screw should be suspended in the air or placed in a special wooden box, and leveled with wood blocks to avoid deformation or damage of the screw.

The inner wall of the cooling water pipe attached to the extruder is easy to scale, and the outside is easy to corrosion and rust. The maintenance should be carefully checked, too much scale will block the pipeline, can not achieve the cooling effect, serious corrosion will leak, so the maintenance must take scale removal and anti-corrosion cooling measures.

Assign a special person to be responsible for equipment maintenance. The detailed records of each maintenance and repair shall be included in the plant equipment management file.