Fault Analysis and Solution of Rolling Roller Table

Cause Analysis of 1. Roller Table Failure

The working characteristics of the rolling table are the high temperature of the billet and the large load of the conveying. The traditional bearing support of the roller has two structures, one is the chain drive structure, the other is the bevel gear transmission structure, the main fault from two aspects, one is the damage of the bearing, the second is the damage of the bevel gear (bevel gear transmission).

1. Cause analysis of roller bearing damage

① The bearing seat changes the design oil gap of the bearing

One of the working characteristics of steel rolling roller table is the high temperature of the billet. When the high temperature billet is transported by the roller table, the heat will be directly transferred to the bearing ring through the roller table shaft, and the bearing will inevitably expand from the ring to the axial and radial direction respectively. The bearing in the traditional bearing seat is in the axial direction. Since the width of the bearing chamber is often more than 10% greater than the width of the bearing, the bearing can expand in the axial direction, and the bearing will not cause "burning". However, in the radial direction, the diameter of the bearing chamber cannot be changed because the bearing seat is a structure fixed by upper and lower bolts. When the bearing ring expands with the continuous increase of temperature, the outer ring of the bearing is fastened by the bearing seat and cannot expand, therefore, the oil gap between the outer rings of the original design will be reduced, and the bearing will generate heat due to the small oil gap between the outer rings, which will quickly increase the bearing temperature until it is "locked".

In order to reduce the temperature and improve the life of the bearing, some enterprises will be designed as a roller bearing through the water structure. This measure has both a favorable side and a negative side to the bearing. The favorable side is to reduce the temperature of the outer ring of the bearing, so that the lubricating oil in the bearing chamber will not be "dried", and the bearing will be damaged due to lack of oil. factor. The downside is to reduce the temperature of the bearing outer ring (the expansion of the bearing ring still exists), the oil gap between the bearing outer rings will become smaller, which will accelerate the heating and damage of the bearing.

The bearing seat caused the bearing does not run concentrically

High temperature, large load and large impact are the unchangeable working environment of rolling roller table. The production of flat roller frame in the production process will appear deformation, fixed in the roller frame of the two bearing will be concentric, installed in the same roller on the two bearings will run in the case of non-concentric, this non-concentric operation caused by the "don't force" are acting on the bearing, bearing life will be greatly reduced.

③ The bearing seat is inconvenient for inspection and refueling.

The characteristics of steel rolling production require that the roller bearing seat must be checked frequently and oiled frequently. The upper cover of the traditional bearing seat is fixed by bolts. To check or oiling, the upper cover of the bearing seat must be opened, and the continuity of steel rolling production does not allow frequent shutdown. Therefore, the bearing will often be short of oil, which will accelerate the damage of the bearing.

④ The bearing seat is not tightly sealed, and water and dust seriously affect the bearing life

The dust produced in the production process of steel rolling is not only much, but also mostly hard metal compounds. These hard dust entering the bearing will seriously damage the bearing and reduce the bearing life. In addition, because of the process or equipment needs, there are many places need to spray water (splash water) on the roller table, water with dust into the bearing chamber, it will be more serious damage to the bearing. The traditional bearing seat has plane contact seals at the upper and lower openings, most of the input and output shaft holes are not sealed, and a few of them are only general blanket seals. In the working environment of large impact, dust and water, most of the time, even if there is a seal, it will not work at all. Roller table bearings operate in a mixture of oil, water and dust, which seriously affects the bearing life.

2. Fault analysis of bevel gear drive roller table

The bevel gear drive roller table has the advantages of smooth transmission and low noise. However, it has the disadvantages of high failure and long replacement time. Bevel gear drive roller table failure is mainly due to bearing damage and bevel gear wear. Due to the roller table of bevel gear transmission, limited by the installation space, the selected bearings are light and narrow series bearings with low life. Coupled with the axial force caused by bevel gears, it is inevitable that the failure rate of the bearings is very high. In addition to the fast wear of the bevel gear of the transmission roller table, if the bearing has a slight axial gap, the bevel gear will change the meshing state and soon "bald tip" cannot operate. Therefore, the failure of bevel gear transmission roller table is often more than two times that of other transmission roller table.

3. Comparison of repair time of rolling roller table fault

Rolling production process, once the roller bearing or bevel gear failure, it must be repaired to reduce downtime. For the chain drive roller table, the time necessary for emergency repair is mainly used in the disassembly and assembly of the upper cover of the bearing seat, which usually takes about 30 minutes. For bevel gear drive roller table, the necessary time for emergency repair is not only the preparation and hoisting time, but also the disassembly and assembly of the upper cover of the bearing seat, the disassembly and assembly of the bevel gear box, and the disassembly and assembly of bevel gear and bearing. It usually takes more than two hours.

2. the best scheme to reduce the rolling roller table failure and repair time

1. The best solution to reduce rolling roller table failure and repair time

From the above analysis, it can be seen that in order to reduce the failure of steel rolling roller table and repair time, it is necessary to change the structure of roller bearing seat and transmission mode. For many years, steel rolling workers have done a lot of research and work. After years of discussion and use, so far, the best bearing seat structure suitable for steel rolling production is the boltless insert bearing seat of national patent technology, the patent number is ZL8.8, and the patentee is its flat. The best transmission mode suitable for the non-frequent forward and reverse starting roller table in steel rolling production is chain drive, and the best transmission mode suitable for the frequent forward and reverse starting roller table in steel rolling production is the overall plug-in structure of the motor single drag.

Specifically, the best structure and transmission scheme of all feeding roller tables, billets and finished product conveying roller tables are: the combination of patented boltless insertion bearing seat and chain drive; The best structure and transmission scheme of all special roller tables such as the front and rear roller tables of roughing mill and the front of furnace (discharging) are: the combination of patented boltless insertion bearing seat and motor single drag transmission.

2. The effect of the best scheme to reduce the failure of rolling roller table and repair time

Due to the national patent technology of the bolt-free insert bearing seat, specially designed according to the working characteristics of the steel rolling production roller table, compared with the bevel gear transmission, although its transmission is not as smooth as the bevel gear, the use of the speed limit is not as high as the bevel gear, but it can fully meet the needs of steel rolling production. The bevel gear transmission structure is used on the steel rolling production roller table, not only does not play its advantages of high speed and stability, on the contrary, more than the chain drive fault, repair time is long, high maintenance costs. As the saying goes, what is the best? Application is the best.

The above scheme is the best because it has the following effects:

① can reduce the production of disposable roller table investment cost (10~20)%.

The service life of the bearing can be increased by 3 to 5 times, and the bearing failure of the rolling roller table can be reduced by 80%.

③ The emergency repair and replacement time can be shortened to 10 minutes (the emergency repair and replacement time of bevel gear drive roller table needs at least two hours), reducing the emergency repair and replacement time by 90%;

④ It can reduce the consumption of spare parts and maintenance cost of rolling roller table by 60%.

A medium profile production line with an annual output of 300000 tons can reduce the investment in some equipment of roller table for factory construction by 100-2 million tons, increase the output by 3-50000 tons per year, reduce the downtime loss due to roller table failure by 250-3.5 million yuan per year, and save spare parts and emergency repair costs by 100-1.5 million yuan per year.

Analysis of the best scheme 3. reducing the rolling roller table failure and repair time

The above best solutions have such an effect, let us analyze their structural characteristics at a glance.

1. The structural characteristics and advantages of the patented bolt-free insertion bearing seat

The patented technology bearing seat is composed of a bearing box composed of upper and lower two pieces and a bearing box positioning frame. The bearing box is inserted in the positioning frame, and the bearing is installed in a bushing sandwiched between the two bearing boxes. The advantages of the bearing seat are as follows:

① The upper and lower insertion structure will not reduce the bearing clearance, and the operation will not be "hard"

Since there is no bolt fixing between the upper and lower bearing boxes of the patented technology bearing seat, when the external temperature rises or the temperature of the bearing itself rises causing the bearing to expand radially, the distance between the upper and lower bearing boxes will increase accordingly, which has the function of adjusting the diameter, allowing the outer ring of the bearing to expand, thus ensuring that the oil gap between the outer rings of the bearing will remain unchanged, and the heating will not be "locked" burned ". In addition, because the bearing box is inserted into the positioning frame, it is free in the vertical direction, and there is a certain gap between the horizontal and horizontal bearing box and the positioning frame, which has the function of aligning. Therefore, the service life of the bearing will not be shortened due to the non-concentricity of the bearing seat caused by the deformation of the roller frame.

The combination of upper and lower insertion structure and chain drive is easy to disassemble and save time.

Since the patented technology bearing seat is an upper and lower insertion structure, after it is used in combination with the chain drive, when the roller table fails, it can operate by opening the transmission chain, lifting the roller table and replacing it with a transmission chain. It does not need to disassemble and assemble bolts like the traditional bearing seat, not to mention disassembling and assembling the umbrella gear box, roller bearing and bevel gear, thus reducing 90% of the emergency repair time and greatly improving the operation rate of the rolling mill.

The upper and lower insertion structure and chain drive combination, can choose heavy-duty series bearings

Using the patented technology bearing seat and chain drive combination, the diameter and thickness of the bearing are not as limited by the installation space as the bevel gear. When designing, various heavy-duty series bearings can be selected according to the needs, and the bearing life can be improved by 2~3 times.

④ Set protective bushing, the upper cover can be opened during operation, easy to check and add oil

Due to the patented technology bearing seat, between the upper and lower boxes, there is a bushing with a special size and a refueling hole. The upper cover can be opened at any time during operation, checked at any time, and refueled at any time, which can ensure that the bearing is not short of oil and has a long life.

⑤ Set protective bushing, reasonable sealing structure and good sealing effect

Due to the patented technology of the bearing seat, a bushing with a special size and an oil filling hole is provided between the upper and lower boxes. A sealing gland can be added between the bushing and the end cover as required to ensure that even if the bearing seat is buried in dust, the dust will not enter the bearing chamber, thereby improving the bearing life.

2, patented technology without bolt insertion bearing seat applicable enclosure.

The patented technology bearing seat is suitable for the following production lines and equipment.

① All conveying roller tables of the rolling production line from raw material loading to finished product packaging.

② Steel plate flattening production line and other production lines on a variety of conveying roller table.

The rolling steel lifting platform eccentric wheel shaft and other metallurgical production line on the various overturning equipment shaft bearing support.

④ Bearing support for low-speed, large-load drive shafts in mining, coal, chemical and other industries.

3. Analysis of structural characteristics and advantages of chain drive

Chain drive than bevel gear drive used in rolling roller drive, has the following advantages:

① Less fault. The first reason is that the chain of the chain drive is a roller chain. During work, the roller of the chain itself and between the roller and the sprocket are rolling friction, while the bevel gear and the bevel gear are sliding friction, and the friction coefficient is different. Two orders of magnitude. Second, the chain drive roller bearings can be selected according to the need for heavy-duty series, the design life of the bearing itself is three times the bevel gear drive roller. Third, the chain drive does not have the axial force generated by the bevel gear drive to the bearing.

② Low cost. One reason is that the roller chain used in the chain drive is a standard part. What we need to process is only a sprocket, which is far less difficult and less processed than bevel gears, bevel gear boxes and connecting shafts. Second, the weight of the sprocket and chain is only three to 1/5 of the weight of the bevel gear, the bevel gear box and the connecting shaft. Third, the width of the roller rack at the chain drive end is only 1/3 of the width of the roller rack at the bevel gear box.

Replace quickly. When replacing the chain drive roller table, it is only necessary to disassemble and assemble the head (using the patented plug-in bearing seat). When replacing the bevel gear drive roller table, it is not only necessary to disassemble and assemble the bevel gear box, but also to disassemble and assemble the bevel gear and bearing when replacing the bevel gear connecting the shaft. Therefore, the time to replace the chain drive roller table is only one tenth of the time to replace the bevel gear roller table.