Harmonic reducer oil leakage causes and solutions

February 16, 2024

Harmonic reducer oil leakage causes and solutions

Principle of harmonic reducer:

The meshing process of flexor teeth and rigid teeth at the pitch circle is just like two pure rolling (no sliding) rings, and the arc length of the two must be equal on the pitch circle at any moment. Since the flexwheel has two less pitch than the rigid wheel on the pitch circumference, the flexwheel must rotate two pitch angular displacement relative to the rigid wheel during meshing. This angular displacement is the rotation of the output shaft of the reducer, so as to achieve the purpose of deceleration.

Structure features: small size, light weight, large transmission ratio, high precision, smooth transmission, high efficiency

Applications: Light industrial robots/robotic arms, precision measuring devices, precision transmission systems with volumetric requirements

Component composition:

Harmonic reducer lubrication requirements

Extreme pressure wear resistance:

The harmonic reducer needs frequent start and stop and frequent reciprocating movement, which is easy to produce wear, resulting in reduced accuracy, so the grease must have excellent extreme pressure anti-wear performance.

Thermal stability:

The joint structure of industrial robot is compact, the heat dissipation is poor, and the temperature of the joint is high because of continuous work for a long time. The grease is required to have good thermal stability and oxidation stability.

Long life:

The harmonic reducer needs to start frequently and reciprocate in a small space to withstand high-speed and high-load operation, which requires that the grease must have long-life lubrication, no carbon deposition, no discoloration, regardless of oil.

Noise reduction:

Due to the friction, vibration and collision of the transmission gear, the harmonic reducer will produce strong noise, requiring that the grease must have a strong oil film thickness and adhesion to effectively reduce noise.

Reducer oil leakage causes and solutions

"Grease doesn't actually damage any robot because it's the softest, and unless you use the wrong type of grease, not the special type of grease, there will be oil leakage in the reducer or robot." Industry insiders point out.

From the selection of the right lubrication grease point of view, reducer lubrication technology is divided into lubricating oil and grease, lubricating oil in the grease differentiation is very thorough, but there is a disadvantage, for the sealing requirements are very high, in Asia, especially Japan, China, most of the use of grease.

At present, most of the reducer is lubricated with grease, its structure is divided into oil and thickener, oil is more than 90% of the Base Oil plus additives, according to different working conditions, the proportion of additives is between 5%-10%, the content of thickener is about 40%-60%, Grease is divided into 000#, 00#, 0#, 1#, 2#, 3#, 4#, 5#, 6#, from 0# to 6#, the higher the thickening agent content, the harder and harder, the harder the oil separation rate and lubrication performance in the reducer is worse.

"If the domestic reducer manufacturers can achieve 100% sealing, it is still recommended to use oil lubrication, but in addition to ABB, other companies seem to have not been able to solve the problem of sealing, so in general, RV reducer recommended 0# and 00# grease, seal a little better recommended 00#, almost recommended 0#, if it is a harmonic reducer, 1# or 2# is recommended."

Different industries, for the reducer lubrication grease requirements are also different. Taking the automobile industry as an example, because the automobile industry is spread all over the Yangtze River, higher requirements are put forward for the high and low temperature performance of oils and fats. At the same time, the automotive industry lubricating oil also needs to have good compatibility with seals to ensure that long-term use does not leak; The requirements for food production equipment to use food-grade lubrication products are increasingly stringent, and for processing and sorting robots and other equipment that have access to food, the lubricants used must meet food safety standards.

In addition to the unreasonable choice of grease

There are mainly the following reasons for the oil leakage of the reducer:

1, the internal and external pressure difference of the reducer: during the working process of the reducer, the various friction pairs inside produce a lot of heat, resulting in an increase in internal temperature and pressure, and the grease under the action of the pressure difference, resulting in the leakage of grease from the gap. The higher the internal temperature rise of the reducer, the greater the risk of leakage.

2, the oil seal structure design is unreasonable: for example, the premise of the oil seal pumping effect is that the contact pressure peak is close to the oil side, when the pressure peak is close to the air side, the oil side pressure gradient is less than the air side pressure gradient, the oil seal must leak.

3, the manufacturing and assembly process is not strictly controlled, such as the amount of oil injection, the finish of the sealing shaft tilt, and the incorrect assembly of the oil seal can cause leakage of the reducer.

At present, many robot manufacturers to solve the problem of grease leakage is to wipe the rag, treat the symptoms and not the root cause, but also increase the workload of maintenance of operators, mainly from the reduction of the temperature rise of the reducer, improve the lubrication of the tooth surface to reduce friction and heat, seal design from three aspects to fundamentally find a solution to this problem.

Author:

Mr. James

E-mail:

sales@cn-lubricantadditive.com

Phone/WhatsApp:

+86 13783582233