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Failure Analysis of Extruder
The extruder is a common plastic machinery equipment. During the daily operation of the extruder, various failures occur in the extruder, which affect the normal production of plastic machinery. Below we will analyze the failure of the extruder.
Common faults and treatment methods of extruder
1.1 Abnormal noise
(1) If it occurs in the reducer, it may be caused by bearing damage or poor lubrication, or it may be caused by gear wear, improper installation and adjustment, or poor meshing. It can be solved by replacing bearings, improving lubrication, replacing gears or adjusting gear meshing conditions.
(2) If the noise is a sharp scraping sound, the position of the barrel should be considered to be skewed, causing the possibility of scraping the shaft head and the transmission bushing. It can be solved by adjusting the barrel.
(3) If the barrel makes noise, it may be that the screw is bent to sweep the cavity or the set temperature is too low, causing excessive friction of solid particles. It can be dealt with by straightening the screw or increasing the set temperature.
1.2 Abnormal vibration
If this happens at the reducer, it is caused by the wear of the bearing and the gear, which can be solved by replacing the bearing or gear; if it happens at the barrel, it is due to the hard foreign matter mixed in the material, and the cleaning of the material needs to be checked.
The main reasons and solutions for screw extruder wear
2.1 The main reasons for the wear of the screw extruder
The normal wear of the screw and barrel of the screw extruder mainly occurs in the feeding area and the metering area. The main cause of wear is the dry friction between the sliced particles and the metal surface. When the slices are heated and softened, the wear is reduced.
The abnormal wear of the screw and the barrel will occur when the screw rings and foreign objects are stuck. The ring means that the screw is locked by the condensed material. If the screw extruder lacks a good protection device, the strong driving force may be twisted and broken. If the screw is stuck, it will produce an unusually large resistance, causing serious damage to the screw surface and serious scratches on the barrel. The scratches on the barrel are difficult to repair. The barrel is designed in principle to ensure that the service life is longer than that of the screw. For the normal wear of the barrel, it is generally not repaired. The method of repairing the screw thread is often used to restore the radial clearance between the inner hole of the barrel and the outer diameter of the screw.
2.2 Solutions to screw wear
The local damage of the screw thread is repaired by the method of surfacing special anti-wear and anti-corrosion alloy. Generally, inert gas shielded welding and plasma argon arc welding are used. Repairs can also be performed using metal spraying techniques. First, grind the outer surface of the worn screw to a depth of about 1.5 mm, then surfacing the alloy layer to a sufficient size to ensure sufficient machining allowance, and finally grind the outer circumference of the screw and the flank of the screw to the outer dimension of the screw to the original size.
2.3 Ring blockage at the screw inlet
This kind of failure is mainly caused by the interruption of cooling water or insufficient flow. It is necessary to check the cooling system and adjust the cooling water flow and pressure to the specified requirements.
(1) The natural life of the extruder is long, and its service life mainly depends on the wear of the machine and the wear of the reducer. Select extruders and deceleration devices with well-designed materials and well-manufactured
In terms of performance, although the equipment investment increases, the service life is prolonged, which is more reasonable considering the overall economic benefits.
(2) The normal use of the screw extruder can give full play to the efficiency of the machine and maintain a good working condition. Careful maintenance is required to prolong the service life of the machine.
(3) The main faults of the screw extruder are abnormal wear, foreign body stuck, link blockage, wear or damage of transmission parts, poor lubrication or oil leakage, etc.