Troubleshooting Method for Burning Bearing Bush of Roller Box of High Speed Wire Rod Finishing Mill
With the demand of production development, the application of new technology and technology and the improvement of the rolling capacity of rolling mill, the contradiction between burning bush of finishing mill roll box and production has become increasingly prominent. Replacement of a roll box takes about 3 to 4 hours. In this way, on the one hand, restricting production can not ensure smooth production; on the other hand, increasing equipment consumption and spare parts consumption, increasing cost expenditure, is not conducive to market competition. Owing to the phenomenon of burning bearing bush in roll box often occurs in high-speed wire rod finishing mill, which troubles the normal operation of daily production. Next, from the maintenance methods, improve management concepts to find solutions to the problem.
1 Mechanical aspect
1.1 Periodic Axial and Radial Clearance Detection
The gear shaft of finishing mill is the output shaft for installing roll ring (roll). This part plays an important role in rolling. This shaft is positioned by bearing bush and bearing. Therefore, once the axial and radial clearance is too large, it will affect the rolling quality, and even cause the burning of bearing bush accident.
1.1.1 Bearing Bush Temperature Monitoring
The bearing bush of the gear axle of the rolling box of finishing mill has temperature detection elements at each point. The temperature of the bearing bush is controlled by PLC through the instrument. The temperature of the bearing bush is displayed on the display screen of the main control room at any time. Therefore, the spot inspector records the temperature of the bearing bush in the computer every day, and draws up the curve of the temperature rise of the bearing bush, searches, and analyses the possible problems, and formulates the replacement cycle of the roll box, as well as the maintenance plan. To achieve preventive and predictive maintenance, eliminate the problem in the bud.
1.1.2 Vibration and Sound Changes
The change of vibration and sound is also one of the measures to judge whether the transmission box and roll box of finishing mill is damaged or not. Experienced point inspectors can make corresponding judgments on the basis of changes in vibration and sound.
1.1.3 Seal
If the axial seal of the gear shaft is not good, there will be cooling water splashing on the bearing bush and bearing. The tiny particles in the cooling water will aggravate the wear and even damage of the bearing bush and bearing. In order to prevent the cooling water from entering the rolling mill, it is necessary to check and replace regularly to ensure good sealing. It is also important to check and repair the sealing of the cover plate of the roll box and the various joints of the box surface, so as to prevent the invasion of cooling water.
1.1.4 Dynamic Balance
The output shaft speed of finishing mill is very high, some of them are over 6000r/min. Therefore, the dynamic balance of the gear shaft is very important. Generally, this problem is considered for machined parts. But most of them are not concentric with the gear shaft. This eccentricity destroys the dynamic balance at high speed. Therefore, the roll ring cap and the gear shaft can be concentric by the modification and the location of the stop.
1.1.5 Tracking Management
Number management of roll box and gear shaft is carried out. Used to track which rolls box, which gear shaft, which problems exist, which SLNA is suitable for use. The high speed rolling mill, the configuration of the roll box and gear shaft requirements are very high, the installation of the roll box, gear shaft is carefully selected, there is no defect. In this way, there is a more reliable guarantee.
1.1.6 Precision of regular disassembly and equipment maintenance and installation
With the above measures, we should also regularly check the transmission box and roll box, and check the parts we can see. The practice has proved that: timely observation, dynamic management will find problems ahead of time. Installation accuracy in the overhaul is also crucial. The installation accuracy data provided by the drawings must be strictly followed and completed step by step without any errors. Axial positioning measures must be reliable. In addition, when overhauling, attention should be paid to the weight of the action, otherwise, it will affect the equipment.
2 Lubrication
2.1 Oil Pollution
Pollution of the lubrication system is one of the main reasons for the chronic wear and direct damage of bearing bushes and bearings, and also one of the important reasons for the burnout of bearing bushes and the damage of bearings. Therefore, various ways of system pollution are carefully analyzed and some measures are taken. Among them, an off-line full-flow oil return filter system was added to the lubrication system. This form of filtration allows the return oil and contaminant 100 in the oil to pass through the filter, enabling the filter to intercept contaminants to a limited extent. The oil cleanliness of the improved system can always be stable in the range of NAS16388 or above. In this way, from the system point of view, the pollution problem is basically solved.
2.2 Regular cleaning of the tank
Remove small particles from oil products. Although the filtration accuracy is very high, some small particles cannot be filtered because of their small diameter. Therefore, they still do great harm to the equipment. These particles include metal powder leaked from magnetic filters and iron oxide powder produced during rolling with cooling water into the system. This powder makes the oil grey and black. These fine powders are compatible with impurities such as oxides produced by high-strength extrusion in oil and gradually form sludge. Therefore, it is necessary to thoroughly clean all kinds of impurities and sludge at the bottom of the tank regularly.
2.3 Periodic testing
Oil products are regularly tested, and the maintenance cycle is determined by the test results. At the same time, the pollution hazard caused by the distortion of protective equipment such as filters is avoided. In this way, a layer of protection is added to the cleanliness of the system oil.
2.4 Preventing cooling water from intruding into the lubrication system
If there is water in the oil, the lubricity of the oil will be greatly reduced, which will inevitably affect the service life of the bearing bush and lead to burning of the bearing bush. The damage of mechanical seal and leakage of the cooler pipeline may cause water in the system. Therefore, free water is released after free precipitation during the shutdown, and dissolved water is removed actively by using oil-water separation equipment in operation. At the same time, a long shutdown time is used to test the pressure of the cooler to verify whether the water leakage occurs or not. To ensure the reliability of mechanical seals and prevent the invasion of cooling water.
3 Operational aspects
Advanced equipment management concept requires that advanced management mode should also be adopted in the operation of finishing mill, putting forward the integration of operation and inspection. Simply put, it means that the operator takes part in the equipment inspection. Because each operator is the direct user of the equipment, they can reflect the minor changes and abnormal phenomena in the operation of the equipment directly and quickly. Therefore, it is very important to combine exercises and checks.
(a) The operator monitors the display of bearing bush temperature during the control operation and reports to the maintenance personnel immediately if there is any abnormal problem.
B) Operators can stop immediately when they find irregular abnormal temperature rise alarm. Maintenance personnel is requested to check and confirm whether the equipment has problems. This can avoid greater equipment damage.
C) In operation, operators can judge some problems of equipment according to their daily accumulated experience, and then summarize them together to reflect on equipment maintenance personnel and arrange maintenance.
4 Management results
After a long time of exploration, some achievements have been made in solving the problem of burning bearing bush in the roll box of finishing mill. In addition to other factors, such as the trial of the new gear shaft, the quality of spare parts and so on, the breakdown of the shaft, burning the bearing bush and other faults, basically solved this problem.
