Research On Technique For Extended Service Life Of Slab Continuous Casting Rolls

Rolls，which are vital to the continuous production and quality control of slab，havea larger quantity compared with any other devices in a slab continuous castingmachine．Withstanding very high level of loads constantly，the slab continuous castingrolls in most steel mills tend to stop serving prematurely，mainly either because ofthermal fatigue cracks on the surface of the rolls or the leak of cooling water from thebore of rolls．A research on the two problems mentioned above is doomed to do muchgood to extending the life of the rolls and promoting the output and the productionefficiency of the slab．The fatigue life of rolls depends on the surface initial cracks of rolls，which aredirectly related to the internal thermal stress of rolls．By means of the finite elementsimulation，several conclusions can be listed as follows：the temperature and thermalstress in the surface and the area near to the surface change periodically，while theyalmost remain unchanged in the other part of rolls；second cooling water’s quenchingeffect on the surface of rolls can make the thermal stress changed from compressive totensile instantaneously and drastically，so the quenching effect enormously promotes theinitial fatigue thermal cracks；to extend roll’s fatigue life desires higher casting speed incontinuous casting process and higher thermal conductivity and lower thermal expansioncoefficient in roll’s material．The maximum amount of leakage of cooling water lies in the water connections in aroll．Analysis shows that the most fundamental reason is the action inconsistencybetween the two adjacent sections of a roll，to which is led by a kind of segmentedmodular structure of a roll，and the relative radial displacement between the two sectionsdoes the maximum damages to the sealing of the water connections．In this article a newkind of sealing structure，which is called flexible water connection with two rigid sleeveson its ends and a QBe2bellow in the middle，is designed．The flexible water connectionis able to buffer the action inconsistency，thereby protecting the seals on the flexiblewater connection and achieving the static sealing effect．The results of the theoretical strength checking and the finite element simulation show that the flexible waterconnection can meet the design requirements and has a high safety factor．...