What are the failure modes of chain drives?

Chain drive. The main failure modes are as follows:

Chain plates. Fatigue destruction.

Under the repeated action of loose edge tension and tight edge tension, the chain plate will be fatigue damaged after a certain number of cycles. Under normal lubrication conditions, the chain plate.

Fatigue strength. It is the main factor that limits the bearing capacity of the chain drive.

rollers, sleeves.

Impact fatigue. Destruction: The meshing impact of the chain drive is first carried out by the rollers.

and sleeves. Withstand. Under repeated impacts, after a certain number of cycles, the rollers and sleeves may be damaged by impact fatigue. This failure mode mostly occurs in medium and high speed closed chain drives.

Pin shaft. with sleeves.

Glue. When lubrication is not done properly or the speed is too high, gluing occurs on the working surface of the pin and sleeve. Gluing limits the limit speed of the chain drive.

Chain hinge wear: After the hinge is worn.

Chain links. It becomes longer, which can easily cause tooth skipping or chain de-chaining. In the case of open transmission, harsh environmental conditions or poor lubrication and sealing, hinge wear can easily occur, which can dramatically reduce the service life of the chain.

Overload Break-Off: This type of pull-off often occurs in low-speed and heavy-load transmissions. At a certain service life, an expression for the ultimate power can be derived from one failure mode. If the lubrication seal is poor and the working conditions are bad, the wear will be serious, and the ultimate power will be greatly reduced.

Extended Materials. And.

Belt drive. In contrast, the characteristics of chain drive are:

1. No. Elastic sliding.

and slippage, I can maintain an accurate average.

Ratio. 2. Required.

Tension. The force is small, and the pressure acting on the shaft is also small, which can reduce the bearing weight.

Friction loss. 3. It can work under harsh environmental conditions such as high temperature and oil stain.

And. Gearing.

In contrast, the characteristics of chain drive are:

1. The manufacturing and installation accuracy requirements are low;

Center distance. When it is larger, its transmission structure is simple;

3. The average transmission ratio of chain drive is accurate, the transmission efficiency is high, the distance between the shafts is adaptable, and it can be used in the environment with high temperature and high humidity; However, the chain drive can generally only be used as a parallel shaft transmission, and its instantaneous transmission ratio fluctuates, and the transmission noise is large.

Encyclopedia. Chain drive.

There are 5 types of failure modes for chain drives. There are mainly fatigue breakage of chain plates, impact fatigue damage of rollers and sleeves, gluing of pins and sleeves, wear of chain hinges, and overload breakage. In order to improve the stability of the movement of the chain drive and reduce the dynamic load, it is better to have more teeth for small sprockets.

However, the number of small sprocket teeth should not be too much, otherwise the chain drive will fail to skip teeth earlier.

Advantages of chain drivesChain drive has many advantages, compared with belt drive, there is no elastic sliding and slipping phenomenon, the average transmission ratio is accurate, the work is reliable, and the efficiency is high; The transmission power is large, the overload capacity is strong, and the transmission size is small under the same working conditions. The required tension is small, and the pressure acting on the shaft is small; It can work in harsh environments such as high temperature, humidity, dust, and pollution.

The following are several failure modes of lifting chain drives:

1. Fatigue damage of the chain.

Because of the alternating stress acting on the chain, the failure mode of the chain is mainly fatigue fracture or fatigue crack and fatigue pitting on the surface of the roller after working for a period of time. The higher the height, the faster the fatigue damage of the chain drive.

Second, the wear and tear of the chain.

When the chain of the chain scatters the large section into or the state regrets the exit of the sprocket, there is a relative rotation between the pin and the sleeve of the chain, and the chain pitch increases after wear, which is easy to cause the jumping teeth to close and detach the chain, and the more teeth of the sprocket, the easier it is to get off the chain after wear.

3. Gluing of the pin and sleeve of the chain.

When the lubrication is not good or the high speed is heavy, the friction surface of the pin shaft and the sleeve is glued and damaged due to the instantaneous high temperature, which limits the ultimate speed of the chain to a certain extent.

Fourth, multiple impact damage.

When the tension is not good, the impact damage is caused by the inertial impact.

Fifth, the static strength of the chain is damaged.

It often occurs at low speed or overload transmission or when there is a sudden impact, the force of the chain exceeds the static strength of the chain and is pulled off.

In chain drive, the general sprocket life is more than twice the life of the chain, so the design of the chain drive is based on the chain design.

Failure modes of belt drive: tooth surface gluing, tooth surface wear, gear tooth breakage, tooth surface plastic deformation, tooth surface pitting.

Design criteria for belt drive: When designing gear drive, it is usually calculated only according to the two criteria of ensuring the bending fatigue strength of the tooth root and ensuring the contact fatigue strength of the tooth surface. For high-speed and high-power gear transmission (such as aero engine main drive, steam turbine generator set transmission, etc.), it is also calculated according to the criterion of ensuring the anti-gluing ability of the tooth surface.

As for the ability to resist other failures, although not generally calculated at present, measures should be taken to enhance the ability of gear teeth to resist these failures.

The main failure modes of belt drive are fatigue damage and slippage of the belt, such as delamination, tearing and breakage.

The design criterion of the belt drive is to ensure that the belt drive has a certain fatigue strength and life without slipping.

Causes of failure of belt drives:

1. When the conveyor belt is rolled into the drum, it will bend, and when the number of bends reaches its fatigue limit, bending damage will occur, and small cracks will appear in the initial stage, and over time, the cracks will expand or tear, which will eventually lead to the breakage of the conveyor belt and cause the failure of the belt drive.

2. Due to the processing error of the drum itself, the surface of the material sticking to the material or uneven wear causes the diameter change, the traction force of the conveyor belt produces the moving component to the large side of the diameter of the drum, under the action of the moving component, the conveyor belt produces a deviation to the larger diameter of the pulley, and the conveyor belt will deviate from the upper part, resulting in the failure of the belt drive.

Failure modes of belt drives: slippage and fatigue failure.

Design criteria: Under the condition of ensuring no slippage, the belt drive has a certain fatigue strength and life.

The main failures are abrasion, gluing, pitting, and tooth breakage. The worm drive is designed according to the contact fatigue strength, and the bending strength of the tooth root is checked.

The main failure modes of chain drive are slope, fatigue, wear, etc.

Extended Resources:

Chain drive is a commonly used method in mechanical transmission, which has the characteristics of large torque, high speed ratio and wide range of variable speeds. Therefore, chain drives are often used in engineering, but there are many failure modes that affect their service life. The main failure modes of chain drives are described below.

1. Slope failure

Due to problems such as improper chain tensioning and poor chain link production accuracy, the distance between the sprocket and the center of the chain changes in the chain drive, which causes the chain to be side-polarized and the ultimate torque is reduced, that is, the slope failure.

2. Fatigue failure

In the process of transmission of chain drive, due to the repeated action of the load nucleus, the stress concentration phenomenon will occur on the chain or gear, which will be aggravated by defects such as burrs and cracks in the stress, and the slight slip and width Zen defects may be manifested in the form of fatigue fracture.

3. Wear and tear failure

In the process of long-term use of chain drive, the chain and gear will rub against each other, and a certain amount of wear will occur with the accumulation of time. In particular, the parts of the chain that are aggravated by wear are prone to gradual development and irreversible failure.

Fourth, elastic failure

Due to the different degrees of force on each component in the chain drive, the bolt and sleeve tend to undergo elastic deformation, which causes the sleeve to move downward, and eventually causes the elastic failure of the chain drive.

In addition, chain drives also have thermal oxidation, high-speed differential, chain jumping and other failure forms. It should be noted that once the chain drive has a letter dust failure, it may lead to serious equipment failure or accidents, so when designing and using the chain drive, it is necessary to fully consider all possible failure modes to ensure that it transmits the required power and movement accurately, stably and safely.

The main failure modes of belt drives are slippage, fatigue failure, and wear of the working face of the belt.

1. Skidding

When the working external load exceeds the maximum effective tensile force of the belt drive, the belt and the small pulley slide relative along the entire working face, and the movement and tension cannot be transmitted, resulting in the slippage failure of the transmission.

2. Fatigue damage

Fatigue damage refers to the phenomenon of material failure under the action of alternating stress well below the strength limit of the material. Fatigue damage will occur in any material, so the time limit for fatigue damage of materials must be taken into account when designing parts and engineering structures, so as to avoid unnecessary property damage and personal accidents.

3. The working surface of the pin back belt is worn

Due to the elastic sliding and slipping of the belt, there is a relative sliding between the belt and the pulley, which makes the working surface of the belt wear.

Advantages and disadvantages of belt conveyor:

1. Advantages: 1. Simple structure, easy to use and maintain; When overloaded, the belt will slip on the pulley to avoid damage to other parts, and it has an overload protection effect.

2. Stable operation, low noise, low vibration, stable transmission, buffer and vibration absorption, and can transmit power between large shaft spacing and multiple shafts.

3. The manufacturing and installation accuracy requirements are not high.

2. Disadvantages: 1. Due to the elasticity and transmission by friction, there is an elastic slip between the belt and the pulley, which cannot guarantee the accurate transmission ratio; Due to the elastic slip in the transmission, part of the power is consumed, and the transmission efficiency is low.

2. Short service life; Compared with meshing transmission, the tension force and on-shaft pressure are larger, and the shaft is easily damaged; It is suitable for high-temperature, flammable, explosive and oil-stained places.

The above content reference: Encyclopedia - with transmission.