What are the measures for the research and development of SEW reducers in Germany
In the use of some power machinery, people often equip these machines with a worm gear reducer. Although people know that in some cases, using these power machines in conjunction with worm gear reducers can increase their service life, they do not know why. To explain this issue clearly, we need to understand the purpose of this worm gear reducer.
What is the use of SEW gearbox?
The SEW gearbox can meet the operational needs of power machinery in certain situations
In many cases, the working speed of power machinery is very high, so these machines cannot be directly used in situations that require low-speed operation. In this case, the worm gear reducer, a mechanical device, can come in handy. By using this worm gear reducer, power machinery can operate at low speeds.
The SEW reducer has a protective effect on the motor during operation.
The SEW reducer can be used independently in environments that require low-speed operation, but the cost of such motors is relatively high, and they are also prone to wear during operation. Therefore, it is more cost-effective to use it in conjunction with a worm gear reducer. Moreover, when used in conjunction with a worm gear reducer, the wear and tear caused by the motor during use will be correspondingly reduced.
Do not mix lubricating oil together
Some people may not be familiar with this type of equipment when they first come into contact with it, and when they find that the lubricating oil inside is not enough, they just add it casually. This approach is very wrong. The correct operating method should be to ask what lubricating oil was used before, and then add the same brand, or simply empty it and replace it with another type of oil. In short, it cannot be mixed.
2： Cool down the machine before changing the oil
Another thing to remind everyone is that when changing the oil in the gearbox, you must not be impatient. You cannot start changing it immediately after turning off the power, as this may not only damage the machine, but also harm yourself due to high oil temperature. It is better to wait for the machine to cool down before starting the operation.
Due to the harsh operating environment of the gearbox, there are often failures such as wear and leakage, mainly including:
1. The wear of the gearbox bearing chamber includes the wear of the housing bearing box, the inner hole bearing chamber of the housing, and the gearbox bearing chamber;
2. The gear shaft diameter of the reducer is worn, mainly on the shaft head, keyway, etc;
3. The bearing position of the gearbox transmission shaft is worn;
4. The joint surface of the reducer is leaking.
The traditional solution to the problem of wear and tear is to repair it by welding or machining after brushing, but both have certain drawbacks: the thermal stress generated by high temperature welding cannot be eliminated, which can easily cause material damage and lead to bending or fracture of components; However, electric brush plating is limited by the thickness of the coating and is prone to peeling off. Both methods use metal to repair the metal and cannot change the "hard to hard" fit relationship. Under the combined action of various forces, it will still cause further wear. For some large bearing enterprises, it is even more difficult to solve on site, and they rely heavily on outsourcing repairs. Contemporary Western countries often use polymer composite materials as a repair method for the above problems, which have excellent adhesion and compressive strength. The application of polymer materials for repair can be done without disassembly or machining, without the influence of welding thermal stress, and the repair thickness is not limited. At the same time, the product has the flexibility that metal materials do not have, which can absorb the impact and vibration of equipment, avoid the possibility of further wear, and greatly extend the service life of equipment components, saving a lot of downtime for enterprises and creating huge economic value.
For the leakage problem, traditional methods require disassembling and opening the gearbox, replacing the sealing gasket or applying sealant, which is not only time-consuming and laborious, but also difficult to ensure the sealing effect, and leakage may occur again during operation. Polymer materials can be used for on-site leakage control. The adhesive strength, oil resistance, and 350% tensile strength of the materials overcome the impact of gearbox vibration and effectively solve the problem of gearbox leakage for enterprises.
Analysis of the causes of oil leakage in SEW gearbox
1. Pressure difference between the inside and outside of the gearbox: During the operation of the gearbox, the friction and heat generated by the moving pair, as well as the influence of environmental temperature, cause the temperature of the gearbox to rise. If there are no ventilation holes or if the ventilation holes are blocked, the pressure inside the gearbox gradually increases. The higher the temperature inside the gearbox, the greater the pressure difference with the outside world, and lubricating oil leaks out from the gaps under the pressure difference.
2. Unreasonable structure design of reducer
1) The inspection hole cover plate is too thin, which can easily cause deformation after tightening the bolts, resulting in uneven joint surfaces and oil leakage from the contact gaps;
2) During the manufacturing process of the gearbox, if the castings are not annealed or aged, and the internal stress is not eliminated, deformation will inevitably occur, resulting in gaps and leakage;
3) There is no oil return groove on the box, and lubricating oil accumulates at the shaft seal, end cover, joint surface, etc. Under the pressure difference, it leaks outward from the gap;
4) The shaft seal structure design is unreasonable. Early reducers often used oil grooves and felt ring type shaft seal structures, which compressed and deformed the felt during assembly, sealing the joint surface gaps. If the contact between the shaft neck and the seal is not very good, due to the poor compensation of the felt, the seal will fail in a short period of time. Although there are oil return holes on the oil groove, they are prone to blockage, making it difficult to fully utilize the oil return function.
3. Excessive oil filling: During the operation of the gearbox, the oil pool is stirred vigorously, and lubricating oil splashes everywhere inside the machine. If the oil filling is too high, a large amount of lubricating oil will accumulate at the shaft seal, joint surface, etc., leading to leakage.
4. Improper maintenance process: During equipment maintenance, failure to remove dirt from the joint surface, improper selection of sealant, installation of sealing components in the wrong direction, and failure to replace sealing components in a timely manner can also cause oil leakage.
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Countermeasures for treating oil leakage in reducers
1. Improving the breathable cap and inspection hole cover plate: One of the main reasons for oil leakage is that the internal pressure of the reducer is greater than the external atmospheric pressure. If we try to balance the pressure inside and outside the machine, oil leakage can be prevented. Although gearboxes all have breathable caps, the breathable holes are too small and easily blocked by coal powder and oil stains. Moreover, every time refueling is done, the inspection hole cover plate must be opened, which increases the possibility of oil leakage and causes leakage in areas that were originally not leaking. To this end, an oil cup style breathable cap was made, and the original thin inspection hole cover plate was changed to 6mm thick. The oil cup style breathable cap was welded to the cover plate, and the diameter of the breathable hole was 6mm, which facilitates ventilation and achieves pressure equalization. Moreover, when refueling, the oil can be added from the oil cup without opening the inspection hole cover plate, reducing the chance of oil leakage.
2. Smooth flow: In order to prevent excess lubricating oil thrown onto the bearing by the gear from accumulating at the shaft seal, it is necessary to make the excess lubricating oil flow back to the oil pool in a certain direction, that is, to achieve smooth flow. The specific method is to open a return oil groove inclined towards the inside of the machine on the lower tile of the bearing seat, and also open a gap at the straight mouth of the end cover, with the gap facing the return oil groove. This way, excess lubricating oil flows back to the oil pool through the gap and return oil groove.
3. Improve the shaft seal structure
1) Improvement of gearbox shaft seal with half shaft output: The output shaft of most equipment such as belt conveyors, screw unloaders, and impeller coal feeders is half shaft, making the transformation more convenient. Disassemble the gearbox, remove the coupling, take out the gearbox shaft seal end cover, machine a groove on the outer side of the original end cover according to the size of the matching skeleton oil seal, install the skeleton oil seal with the spring side facing inward. When reassembling, if the distance between the end cover and the inner end face of the coupling is more than 35 mm, a spare oil seal can be installed on the shaft outside the end cover. Once the oil seal fails, the damaged oil seal can be removed and pushed into the end cover, thus saving time-consuming and laborious processes such as disassembling the reducer and coupling.
2) Improvement of the shaft seal for a reducer with a full shaft output: The output shaft of a reducer with a full shaft transmission does not have a coupling. If modified according to the 2.3.1 plan, the workload would be too large and impractical. A detachable end cap was designed to reduce workload and simplify installation procedures, and an attempt was made to use an open type oil seal. Machine the groove on the outer side of the separable end cap. When installing the oil seal, remove the spring and saw the oil seal into an open shape. Insert the oil seal onto the shaft from the opening and use adhesive to connect the opening upwards. Then install the spring and push it into the end cap.
4. Adopting new sealing materials: For leakage at the static sealing point of the reducer, a new polymer repair material can be used to block it. If there is oil leakage at the static sealing point during the operation of the reducer, surface engineering technology's oil surface emergency repair agent adhesive polymer 25551 and 90T composite repair material can be used to block it, thereby achieving the goal of eliminating oil leakage.
5. Serious implementation of maintenance process: During the maintenance of the reducer, the process specifications should be carefully followed. The oil seal should not be installed backwards, the lip should not be damaged, the outer edge should not be deformed, the spring should not fall off, the joint surface should be cleaned, the sealant should be evenly applied, and the oil filling amount should not exceed the oil dipstick scale.
6. Wiping: By treating the static sealing points of the reducer, it is generally possible to achieve no leakage or seepage. However, due to aging and poor sealing components, improper assembly, and high surface roughness of the shaft, there are still slight leaks at the dynamic sealing points. Due to poor working environment, coal dust adheres to the shaft, making it appear oily. Therefore, it is necessary to wipe the oil stains on the shaft after the equipment stops running.