I believe everyone is familiar with twin-screw granulators, which are mainly used for filling rubber and engineering resins, processing high water absorbing resins, and other work. When working, if there is a phenomenon of screw slippage, it needs to be resolved based on factors such as high back pressure, failure of the check ring, wear of the barrel or screw, and improper hopper planning. In this article, the editor will provide a detailed introduction to the solutions for screw slippage in twin-screw granulators and their regular maintenance work.
Solution to screw slippage in twin-screw granulator:
During the use of twin-screw granulators, there may be a phenomenon of screw slippage. If these situations are not resolved, they will have a significant impact on the entire machine. Below, the editor will provide a detailed introduction:
1. Too high back pressure
If the back pressure is set too high, the screw may not be able to generate enough forward pressure to overcome the back pressure of the molten material. The screw will rotate in a certain direction without retreating, which will do more work on the molten material and significantly increase its temperature, thereby affecting the quality and cycle time of the finished product.
2. The reverse loop has malfunctioned
When the screw rotates and plasticizes the material, the check ring should be in the front position, in contact with the fixed ring seat. If the anti reverse ring is in a backward state or between forward and backward states, the molten polymer will have resistance when passing through the gap between the anti reverse ring and the ring seat. If there is suspicion of a problem with the check ring, it should be replaced immediately.
3. Wear of barrel or screw
Similar to the feeding section, when the resin melts in the screw tightening section, it adheres to the wall of the barrel. When the screw rotates, the material is subjected to shear force and separates from the barrel wall, and is transported forward. If there are wear areas on the screw and barrel, the screw cannot effectively transport materials forward.
4. Improper hopper planning
The correct hopper planning is the key to ensuring the stable transportation of materials. Generally speaking, uniformly sized new pellets run well in a square hopper with a sudden contraction zone. However, this is not the case when participating in recycled materials. By disrupting the shape and size of the granules again, it will affect the uniformity of the feed. Inconsistent feeding means that the screw cannot maintain uniform transport pressure on the melt, resulting in slippage.
Regular maintenance of twin-screw granulator:
Generally, the twin-screw granulator is shut down for regular maintenance after running continuously for 2500-5000 hours. The machine needs to be disassembled for inspection, measurement, and identification of the wear of the main components, replacement of parts that have reached the specified wear limit, and repair of damaged parts.
1. Possible reasons for the inability to increase or decrease temperature: whether the thermocouple is loose; Is the heating zone relay working properly; Check if the solenoid valve is working properly, if the heating rod is detached or damaged, replace the heating rod in a timely manner, and tighten the screws.
2. Timely clean the dirt in the vacuum tank and the materials in the exhaust chamber to ensure smooth pipeline. If the sealing ring of the vacuum pump is worn, it needs to be replaced in a timely manner and checked regularly. If the output shaft jumps, it is definitely due to bearing damage and the shaft has broken, and it must be opened and replaced. If the bearing positions of the two output shafts of the gearbox are worn too severely, the box must be replaced to avoid greater losses due to faults.
3. The motor that drives the screw to rotate should be inspected for brush wear and contact, and the insulation resistance value of the motor should also be measured regularly to ensure it is above the specified value. In addition, check whether the connecting wires and other components are rusted and take protective measures.
4. When the twin-screw granulator needs to be stopped for a long time, anti rust lubricating grease should be applied to the working surfaces of the screw, machine shaft, and machine head. Small screws should be suspended in the air or placed in wooden boxes, and leveled with wooden blocks to prevent deformation or damage to the screws.
5. The cooling oil in the cooling oil tank attached to the twin-screw granulator should be added in a timely manner. If black sediment is found in the cooling oil, it is necessary to filter the cooling oil and add new oil in a timely manner. Careful inspection should be carried out during maintenance, as burning of cooling oil is detrimental to the pipeline and cannot achieve the cooling effect.
The above is the solution for screw slippage in twin-screw granulators introduced by the editor, as well as its regular maintenance work!