Technical support Maintenance After rolling one short period,the hardness of rolling surface arise 3-4 HRC and strain hardening layer producing causes fatigue effect,which brings crack and spalling.The only way to decrease the possibilities of crack and spalling,elongate the roll¡¯s life is to remove the phase-transformation layer in advance. According to our statistics,the following data will help you to maintenmance your roll to keep good condition:
A.Relation between the depth of cut and cracks possibility
Roll Description |
Depth of grinding(mm/dia) |
Possibility of crack |
1st Intermediate Roll |
0.1 |
2% |
0.25 |
1% |
2nd Intermediate Roll |
0.1 |
2% |
0.25 |
1% |
B.The grinding Date of Roll
Material |
|
Rough Grinding |
Finish Grinding |
|
Grinding wheel |
CBN |
GC |
M1. |
Grain Size&Grade |
#170.75 |
220j8B |
M2. |
Infeed |
0.02 mm/pass |
0.005-0.01 mm/pass |
M7. |
Wheel Speed |
1800 m/min |
1800 m/min |
M42 |
Roll Speed |
64-100 rpm |
64-100 rpm |
C.Standard Grinding Depth
Type |
Depth of grinding(mm/dia) |
Per Operation period |
D2 Work roll |
0.03-0.05 |
1coil |
M2 Work roll |
0.01-0.02 |
1coil |
1st Intermediate Roll |
0.1-0.25 |
72hrs |
2nd Intermediate Roll |
0.1-0.3 |
144hrs |
D.instruction of Crack and Spill 1.Evan rolling compression higher,the cracks may not be found,however the micro structure could be transmuted.The phase-transformation layer should be removed,otherwise the phase-transmutation will result in cracks in the future. 2.When crack and spill happened,it¡¯s important to promptly cut this layer;otherwise rolls will be damaged in the early stage.Prolong the use of roll is to inspect in the primary. 3.Prolonged use and not following the recommendation for depth of cut for grinding request,the fatigued layer will accumulate on the surface of roller and spill and crack on the surface layer could be happen. General Maintenance Report Roll Type: Roll No: Diameter: Roll Material: Arrival Date: Hardness:
No. |
Operation Period |
Work Hours |
Total Work Hours |
Rolling Quantity (MT) |
Total Rolling Quantity (MT) |
Dia (mm) |
Depth Of Cut |
Hardness |
Rolling Accident |
Remark |
1 |
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2 |
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3 |
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4 |
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5 |
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6 |
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7 |
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8 |
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9 |
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10 |
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11 |
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12 |
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