Have you ever had a problem with your paper machine cylinder?

Do you know the most problematic areas in a paper machine cylinder dryer?

 

Usually the cylinder failure is divided into two main categories: bearing failure and cylinder failure.

Bearings often fail mainly wear, fracture, fatigue, corrosion, indentation and glue failure, etc..

Cylinder failure is mainly manifested as cylinder imbalance, uneven wear of cylinder surface, etc.

 

What should you do if your high-speed paper machine cylinder bearing fails?

 

Here are some causes and corresponding solution of the cylinder bearing failure in high-speed paper machines.

 

Causes: 

• The load of cylinder bearing
• Lubricants
• Working environment

Solutions

• Countermeasures for load causes
• Countermeasures for lubricant causes
• Countermeasures for environmental causes

 

Straight to the point

Why does the cylinder bearing failure appear?

Cylinder bearing is one of the most worn bearings in the paper machine., and it is spherical roller bearing, its load capacity is relatively strong; the pressure of the bearing is relatively large.

 

The consequences of in-service cylinder bearing failure we should know:

There is no doubt about the economic loss

Abrasive debris from wear enters the lubricating oil, which may cause damage to the drying cylinder gears and result in greater equipment accidents, leading to constant maintenance of the paper machine.

The axial tilt of the drying cylinder makes the dry blanket runaway and the motor overload stop.

Causes excessive noise and substantial harmful vibration, and even makes the paper break.

Sometimes it even leads to scrapping of the dryer blanket, fire of the machine and transmission failure.

Causes of the cylinder bearing failure

Since the cylinder bearing failure caused by the heel is so serious, then we must know the causes of cylinder bearing failure:

1.The load of cylinder bearing

The cylinder bearing not only has to bear the weight of the cylinder, but also has to run 24 hours a day, therefore, its load pressure is quite large. In the production operation of large enterprises, once the equipment is running, it is almost impossible to stop, and the damage to the dryer is very obvious in the continuous operation mode. In addition, the cylinder bearings are generally of sealed design, which makes maintenance difficult.

 

2.Lubricants

Lubricating oil plays a vital role in the operation of equipment and is of great significance in reducing equipment wear and keeping it running well.

 

However, poor quality lubricating oil to dry cylinder bearing damage role is also very obvious, if the lubricating oil contains water, there will be additive precipitation and catalytic oil oxidation, so that the lubricating oil film rupture, thinning, can not well protect the metal surface of the bearing, so that the inner and outer ring of the bearing rolling body metal surface direct contact accelerated bearing surface, increase the loss, resulting in fatigue failure, corrosion failure.

 

In addition, impurities more lubricating oil will also silt bearing parts, leading to bearing can not run, and even some lubricating oil will cause equipment particle pollution, and then damage the bearing.

 

3.Working environment

The main function of the drying cylinder is to dry the moisture in the paper sheet to achieve the purpose of drying. The higher the temperature, the faster the drying speed of the paper sheet, the more moisture evaporates from the paper sheet, and the more humid the environment becomes.

 

Therefore, the higher the efficiency of the high-speed paper machine, the higher the temperature of the environment in which the dryer bearings are located, and the more humid the environment is, the more damage such an environment can do to the equipment.

 

Enterprises to improve the production quality and speed of products, vigorously raise the temperature of the drying cylinder to speed up the drying speed, and drying cylinder bearings because of the principle of thermal expansion and contraction, making the bearing clearance becomes larger, high temperature makes the lubricant viscosity low, the oil film becomes thin, increasing the degree of loss of equipment, greatly shortening the service life of the drying cylinder bearings.

 

Out of the above reasons , there are many factors that lead to the failure of cylinder bearings. For example：

• the wrong choice of cylinder bearing,
• poor bearing quality,
• bearing-shaft clearance selection is not appropriate,
• the installation process is not correct (i.e. bad installation),
• the use and maintenance of improper (lubrication deterioration, deterioration of working conditions and load overload)

Corresponding solutions of the cylinder bearing failure

Because there are many causes of cylinder bearing failure, I proposed the corresponding solutions based on the causes I detailed.

1.1Countermeasures for load causes

The high speed paper machine itself has a mass of more than 20 tons, plus the daily production of thousands of tons of products, you can imagine how much load the dryer bearings will bear. Overuse of the dryer bearings will undoubtedly accelerate the aging of the equipment and lead to fatigue failure. In order to solve the premature failure failure caused by the load problem, the following measures can be taken.

 

(1) Timely overhaul equipment, once the equipment damage is found, replace the cylinder bearing parts in time, or try to use high-quality, wear-resistant bearings and accessories.

 

(2) Equipment in use if suddenly overloaded, will cause irreparable damage to the equipment, therefore, in use to timely overhaul, try to avoid the fatigue pitting situation. Once fatigue pitting occurs, a maintenance plan should be made in time to ensure the normal operation of the equipment.

 

1.2Countermeasures for lubricant causes

The protective role of lubricating oil to the equipment is self-evident, through improving the use of lubricating oil and its quality quality, can extend the service life of the equipment, specific measures are mainly.

 

(1) Clean up the pollution port of the bearing oil groove in time, check and clean regularly, and reduce the probability of the collagen failure;

 

(2) Install the oil -water separator on the bearing to accelerate the dehydration of lubricating oil and reduce the bearing corrosion failure caused by exceeding the standard of water;

 

(3) Before the lubricating oil maintenance of the equipment, scientific measures can be taken to reduce the moisture content in lubricating oil. For example, you can use a filter car to dehydrate to its vacuum;

 

(4) Check the distribution valve of the cleaning cylinder bearings at a regular point to reduce the probability of erosion failure caused by equipment pollution;

 

(5)Regularly clean and replace the oil tank respiratory filter element, strengthen the sealing work during maintenance.

 

1.3Countermeasures for environmental causes

A high temperature and humid environment will cause the equipment to erode and corrode. At the same time, thermal expansion and contraction will cause the dislocation of the inside and outside of the baking cylinder to become larger and the gap between the inside and outside of the bearing will be reduced, which makes the lubricating oil film thinner and cannot play a protective effect.

 

In response to this situation, the top ring of the bearing outer ring should be removed, and then a pad as thick as the top ring size of the outer ring on the inner ring of the bearing. As for the size of this size, it depends on the gap between the axial changes in the axis of the bearing of the cylinder bearing during thermal expansion.

 

In addition, the vibration of the external environment can also cause corrosion to the device. In response to this situation, the each part of the equipment is separated or added with a shock pad.