Four-row cylindrical roller bearings for rolling mills mainly include FC type (four-row cylindrical roller bearing with one inner ring), FCD type (four-row cylindrical roller bearing with double inner ring), FCDP type (double inner ring with flat retaining ring) Four-row cylindrical roller bearing with inner ring).
The operating characteristics of roll bearings are harsh operating environment, large operating load, high unit pressure, large heat generation, and short lifespan. Compared with ordinary bearings, it has many different features.
From the point of view of application, roll bearings must have excellent smoothness and cooling conditions, and the radial dimension should be as small as possible. The operating conditions of the support roll and the work roll are very different, and the bearing types and smoothness used are different.
The primary application conditions for roll bearings to be extra thoughtful are:
① Rotation speed: Not only do you want to think about the maximum speed here, sometimes the slow speed is also a question, and the slow speed does not simply constitute a smooth oil film;
②The force is large: and the force of many rows of tumbling bodies is uneven, and sometimes even some rows are not stressed;
③The inner and outer rings are misaligned: This is mainly related to the bearing clearance, which directly affects the accuracy of the rolled plate and strip;
④Axial force: As for the four-row cylindrical roller bearings for rolling mills, because they cannot accept the axial force, other considerations should be taken;
⑤High temperature: This is an element that may cause poor smoothness.
From the viewpoint of bearing manufacturing, the materials must have the characteristics of high load-bearing capacity, low conflict coefficient, impact resistance, and ability to absorb hard particles entering the bearing; for roll bearings with a large scale, once the scale exceeds a certain scale, data, skills, and manufacturing Waiting will be different; for example, for some grades of fully hardened steel, if the size is too large, it is not so simple to want to harden.
For some special bearings, higher surface roughness is requested, the rollers need special shapes, special materials and formulas, etc. Nowadays, there are still many doubts about the manufacture of large bearings by domestic manufacturers, and the roll bearings of the primary equipment still need to be imported.
From the perspective of roll system structure planning, whether the bearing equipment is reasonable or not is the condition for the rolling mill to meet the requirements of the rolling material and the normal operation of the rolling mill bearing. Nowadays, copper strip processing and rolling mills are increasingly developing in the direction of high speed, high load, high precision and high reliability. The use of four-row cylindrical roller bearings with thrust bearings is constantly increasing. This equipment mainly has the following advantages:
①Under the condition of the same section size, its radial load bearing capacity can be the largest, that is, for a certain roll body diameter, it can accommodate the largest roll neck diameter;
②The radial load and the axial load are respectively borne by two kinds of bearings, each of which exerts its characteristics and can be used to higher rolling speeds;
③The axial movement is independently controlled by the thrust bearing, which can obtain a smaller axial gap than the double-row spherical roller bearing and the four-row tapered roller bearing, which is conducive to the improvement of the precision of the plate and strip;
④The accuracy of the bearing is easy to improve and ensure, which makes it more reliable and can roll more high-precision products;
⑤The inner and outer rings of the bearing can be separated, making it easier to disassemble the roll equipment;
⑥The inner ring of the bearing works closely with the roll neck to avoid the burning of the bearing when running on the inner ring;
⑦Repair and check brief;
⑧Bearing application is low cost.
From the above, because of the operating characteristics of the rolling mill, the usual cylindrical roller bearing with the same inner diameter is compared with the special bearing for rolling mill. The special bearing for rolling mill has the characteristics of small outer diameter, wide width, large load capacity, and low limit speed. . According to the JB/T5389.1-2005 rule, when the rolling mill bearing parts are made of carburized steels G20Cr2Ni4 and G20Cr2Ni4A that conform to the GB/T3203-1982 rules, the depth of the carburized layer and the heat treatment quality should conform to the JB/T8881-2001 rules; rolling mill bearings When the parts are made of high-carbon chromium steel GCr15 and GCr15SiMn conforming to the rules of GB/T18254-2002, the heat treatment quality should conform to the rules of JB/T1255-2001.
In addition, according to the operating characteristics of the rolling mill and environmental factors, rolling mill bearings usually have irregular life spans.
Moreover, for high-precision plate and strip rolling mills, in order to ensure the reliability of the roll system accuracy, usually when selecting four-row cylindrical roller bearings for rolling mills, a certain margin should be left for the outer circumference of the inner ring of the bearing. After the bearing inner ring equipment is placed on the roll, it will be ground together with the roll to the required size to ensure accurate radial clearance, and the coaxiality between the inner diameter and outer circle of the bearing and the roll surface can be obtained with a higher comparison, so as to ensure The precision of the processed plate and strip.
