During the use of rolling mill bearings, the bearing rings and rolling elements must bear high contact force and impact load, so the rolling mill bearings are made of high-quality high carbon chromium bearing steel or high-quality carburized bearing steel.
High carbon chromium bearing steel: GCr15、GCr15SiMn、GCr18Mo；
Carburized bearing steel: G20Cr2Ni4A、G10CrNi3Mo；
Raw material inspection: high carbon chromium bearing steel, GB / T 18254-2002, technical specification for carburized bearing steel, GB 3203-82.
A. Advantages of improving the accuracy grade of rolling mill bearing: (strictly in accordance with GB / t307.1 "rolling bearing radial bearing tolerance" standard implementation)
① The improvement of dimensional accuracy of bearing parts is conducive to improving the matching accuracy of relevant matching parts and improving the service life of bearings.
② The results show that the roughness grade of the bearing working surface is improved (the roughness peak value is reduced), which is conducive to the formation and protection of the bearing lubricating oil film, and the fatigue life of the bearing is significantly improved.
③ The improvement of bearing precision can make the rotation flexibility of the bearing better, which is convenient to use at high speed, reduce the bearing heating, and improve the bearing life.
④ The bearing accuracy is improved, the vibration and noise of rolling mill equipment are reduced, and the accuracy of final products in metallurgical industry is improved.
B. Selection of mill clearance (in strict accordance with GB / t4604 rolling bearing radial clearance):
Because the working condition of rolling mill bearing is bad, the rolling load, speed, lubrication, temperature rise, fit interference and rotation accuracy should be considered. The principle is that the smaller the bearing clearance is, the better the service life of rolling mill bearing is.
Judge whether the bearing clearance is appropriate according to the damage of the bearing:
① If the clearance is too small, the bearing is easy to overheat and burn out; when the lubrication conditions and load meet the use requirements, the heating phenomenon still appears, so it can be considered that the working clearance of rolling mill bearing is too small.
② The larger bearing clearance leads to the smaller bearing load area (the ideal load area is 120-150 degrees), which increases the unit stress in the bearing area and easily leads to overload fatigue spalling, which affects and reduces the service life of the bearing.
Bearing production flow chart:
Strictly implement JB / t5389.1 "four row cylindrical roller bearings for rolling bearing rolling mill" and JB / t5389.2 "double row and four row tapered roller bearings for rolling bearing rolling mill"
① Improve grinding process, prevent and eliminate grinding burn and crack, use flaw detector to check parts crack, prevent and reduce bearing parts fracture failure.
② The working surface of the bearing is machined by superfinishing machine to improve the roughness accuracy of the working surface and make the surface in the state of compressive stress, so as to improve the contact fatigue life of the bearing.
③ Strengthen the site management, avoid the work surface scratch, reduce fatigue damage stress source.
④ The rolling element adopts full crown (or semi crown) roller to avoid or reduce the edge load and improve the service life of bearing.
⑤ Accurately control the grouping of rings and rollers to ensure that the sizes of bearing outer circle are different from each other and the bearing clearance is consistent, so as to ensure that the four rows of rollers are stressed at the same time.
⑥ The residual magnetism of bearing parts and the cleanliness of bearing meet the requirements of industry standards, so as to avoid fatigue spalling damage caused by dirt.