Why the back up roll you bought not durable?

Due to the environment in which the back up roll is used, it must withstand a large radial force, so it is the most critical mechanical part of the equipment in addition to the work roll. Many equipment manufacturers do not understand the structure of the back-up roll, and assemble the back-up roller by themselves with ball bearings and bushing parts, which is extremely not durable, and the accuracy is not good, which affects the use.

The good quality back up roll should be composed of mandrel, bearing sleeve, needle roller, seal, fastener, heat-resistant extreme pressure grease, and the heat treatment hardness, material selection, clearance fit, assembly and debugging of each part have specifications and requirements. In the tension leveling line below 450 m/min, the service life of the back up roll should be between half a year and two years (depending on the initial plate type and use environment), if the back up roll  is broken in two or three months, please inform the supplier in time, basically for quality problems or improper use.

There are three reasons why the back up roll are not durable:

1. The quality of the back up roll . If you open the back-up roller, you will find that the internal structure is assembled with standard parts such as bearings, which is basically an inferior product. The inside of the back up roll should be composed of needle rollers or needle rollers with cages, and the back-up roller itself is a non-standard bearing. Install the back up roll on the roll cassettes, measure its circumferential runout, if the circumferential runout is greater than 0.01mm, it is also defective, please replace it in time.
2. Wrong selection. When the sheet material exceeds 0.3MM or the production speed of the drawing line exceeds 300m/min, it is not recommended to use light-duty back up roll with cages, but heavy-duty back up roll with fully loaded rollers. After dismantling the back up roll, if the internal rollers (cylindrical needle rollers) are wrapped by a ring cage made of nylon, brass, cast iron, etc., then the roller is a light-duty type, and it is recommended to find the supplier to replace it.
3. Poor accuracy of the roll cassettes. The accuracy of theroll cassettes directly affects whether the back up roll can contact the work roll or the intermediate roll, if the back up roll rotates and some do not rotate when the machine is working, it means that the back up roll that does not rotate does not bear the load, and the back up roll installation surface of the roller box is high and low. This will make the back up roll unevenly loaded, the force is bad fast, and the force is not effective. It is recommended to reprocess the mounting surface of the roll cassettes, and it is best to grinding the part again.