1.What kind of material does your company make to rolls?
For rolls material,here we have steel rolls also with iron rolls.
For steel rolls,we have material high chromium steel roll,high speed steel roll,graphite steel roll,ssemisteel roll and the other material which is based on the requirement from the customers.
For iron rolls,we have chilled cast iron roll,infinite chilled cast iron roll,spheroidalgraphite roll,high chromium cat iron roll and the others which is based on the requirement from custoemrs.
2.How to improve the rolls using life
1. Preheat.Before the running of the rolls,we make the preheat.In this case,we can shorten the temperature gradient on rolls surface and inner to reduce the stress.
2. Cooling of rolls:As the rolls with high alloy content for hot strip mill finishing work mill stand,the thermal conductivity of the rolls is not good that the water cooling is important for the rolls.General speaking,the temperature on rolls surface for roughing rolls should be with 70℃ meanwhile finishing rolls with 60℃.The rolling mill both for domestic and international,the average water consume for every cm rolls length has added from 3m³/cm.h to 5m³/cm.h.The adding for cooling water is not only reducing the crack of the rolls but also offering the better usage condition for choosing the more wear resistance material.
3. Grinding of rolls:Grinding is the most efficient way for eliminating the roll crack,preventing the rolls broken and spalling.After the roll has off the mill,the inspection report record is necessary.The grinding area should be added to eliminate all the crack.To eliminate the crack absolutely,NDT should be cooperated in,as magnetic particle inspection and ultrasonic inspection.
4) Scientific design and material selection:If the concavity formed in the middle of the roll ,the stress will focus on the two side of rolls or on the back up roll. In serious cases, the shoulder of the work roll will fall off, and even the shoulder of the support roll will fall off.To avoid this accident,we should consider the reasonable design of the rolls.
5) Choose the reasonable back up type:The reasonable roll type design can efficiency prevent stress concentration.Usually to say,we will make the compound chamfer.
6) Accident settle:we should immediately stop the water cooling when card steel,heaped steel,laminated steel appears.We should raise the rolls and make it leave the hot strip and let it cool.Before it enters into the mill,we should reduce the defect absolutely.
3.If any quality problem,how could your company settle it?
1. we will check what type of the problem is and how could it happen?
2. If it is our full duty,we will replace the new piece for our customer meanwhile we will pay the full duty for the transportation and the other fees caused by re-import.
3. We will settle the quality problem until the satisfy of the customers.
4.If we know nothing about the product,what will your company do?
1. before the purchasing order,we will give the professional proposal for what kind of material is better for your choise.
2. when you have bought the product,we will give the professional advise on how to improve the using life meanwhile how to make the maintain of the rolls.
3. when you have used it and problem appears,we will give the advise on how to reduce the accident case during the production
4. Any question which is revelant to the products,we will make the answer within 2 days with professional advise.
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