BN-S20 Solid CBN inserts turning surfacing rolls instead of
As we all know, rolls will appear defects, such as cracking and spalling because of long period usage. Or rolls diameters can’t reach the dimension requirement, then we will choose restoration technology (like surfacing) to make the rolls repaired its original dimension, which is called Rolls repair.
Rolls, as the main part of the Rolling mill, the rolls quality decide the working efficiency and the product quality and rolls are consumable parts, so the rolls quality also decided the rolls consummation. When the rolls appear defects or substandard dimension, we usually use surfacing technology repair the rolls body and journal, which not only decrease the processing cost, but also improve the machining efficiency and realize our basic national policy of energy saving, recycling economy which are very popular in many rolls factories
The following will introduce some tips before restore the rolls and how to machining restored rolls?
1. Rolls before Restoration
(1) Clean the rolls surface: If the rolls failure modes are cracks, we need to completely clear all the cracks.
(2) Ultrasonic Inspection: Check whether the rolls have defects which will affect the usage or not, especially whether the cracks are clean
(3) Remove the rolls heat: Reduce the cooling rate between the metal and Heat affected zone in the surfacing process, and reduce hardened trend and decrease the welding stress.
And the preheating temperature need be decided by the carbon content and alloy content of the rolls materials and welded materials
2. Rolls Restoration
We need choose restored methods depending on the rolls product, materials, dimension and failure mode. For example, SMAW welding suit for small quantities and irregular rolls restoration and on-site repair. Electro slag welding suited for large flat rolls. Submerged arc welding is a welding method which most widely used in surfacing roll areas, and it can realize automation and mechanization, and has no arc radiation, has good working conditions.
3. Rolls after restoration
Rolls need to do heat-treatment after restoration in order to eliminate welding stress, improve roll performance, and prevent the generation of delayed crack. Then machined the rolls and recovered roll surface roughness and dimension requirements.
Recovered the roll surface dimension and precision has two methods: grinding and turning. With the development of the modern technology and continuous research of Turning inserts industry, we finally researched cutting tools materials which can use turning instead of grinding. Especially Halnn researched non-metallic adhesive BN-S20 CBN inserts, which can realize high-efficiency machining Surfacing roll, and improve the processing efficiency and lower the processing cost.
Halnn,as one of the manufacturers which offer solutions and the environmental advocates, continued to innovate, enhance core competitiveness of products, clients gradually expanded to various mechanical industries.
Halnn always offer customer high-quality, high-performance tool products and can quickly meet the increasingly diverse needs. Halnn committed to making the world no longer have difficult to machine materials.
For large-scale rolls, we usually use turning instead of grinding process, for example Halnn BN-S20 Solid CBN inserts machining the restored rolls, the precision can reach Ra0.4. But if the rolls required precision above Ra0.4, we recommend that grinding after turning.
If you would like to know more details on machining rolls, please click http://www.halnncbn.com/Solution/Mill_Rolls.html ,Or feel free to contact with us info@halnntools.com, Or whatsapp:+8615617635382.