The Reason:
1) The friction of the rolling groove after changing the roll and groove is too small, causing the head of the rolled product to slip;
2) The head of the rolled product is tilted out of the rack, causing it to fail to bite into the downstream rack or the head guide position smoothly;
3) There are foreign objects in the rolling groove or guide groove;
4) The billet is severely out-of-square, unable to enter the rolling mill or take out the outlet pipe;
5) The blank is split out of the guide or wrapped around the roller.
Solution:
1) Increase the groove friction when changing rolls and grooves. Grind the grooves with the grinder or use spot welding, and turn off the cooling water of the rolls until they are completely bitten.
2) Check whether the guide base is loose and whether the rolling line is centered, and replace the old guide in time.
3) In the rolling process, timely clean up the oxide scale;
4) In the rolling process, unqualified billets are removed in time, and splitting occurs. Emergency stops should be taken as soon as possible to reduce the waste steel processing time.
2. Piling of the Middle and End of the Rolled Piece
The Reason:
1) Due to improper roll gap setting caused by improper size of rolled products, stacking steel;
2) Defects of the billet, such as inclusions, bubbles, etc., are broken during the rolling process and cause stacking of steel;
3) The speed of the rolling mill is improperly designed, and it is in the state of stacking and rolling. When the first half of the rolled product is maintained by the front rolling mill to maintain micro-tension rolling, when the tail of the rolled product leaves the front rolling mill, the tension is suddenly lost there, causing the stack at the stand tail;
4) Sudden increase or decrease in speed of the rack motor caused the stacking of steel;
5) The roll was suddenly broken or the guides were severely damaged in the first few passes, which caused the stacking of steel.
Solution:
1) After changing rollers and grooves, accurately set the groove bottom, correctly measure the diameter and speed of the rollers, and reduce speed errors
2) Strengthen the inspection of unqualified blanks;
3) Correctly adjust the tension between each frame;
4) Inspect electrical equipment and replace damaged electrical components;
5) Check the amount of roll cooling water, adjust the steel temperature, and prohibit rolling of low temperature steel and blackhead steel.
3. Piling steel between Finishing Mill Stands
The Main Reason:
1) The guide wheel does not rotate or the bearing burns;
2) splits of rolled products;
3) The guide or roller ring is incorrectly installed;
4) Improper roll gap setting or improper incoming size;
5) the roller ring is broken;
6) The broken line causes the rolling line to break automatically.
Solution:
1) Replace the guide, and strengthen the correctness of the guide installation;
2) Strengthen the blank inspection and lengthen the cutting head;
3) Recheck and adjust the roll gap;
4) Replace the roller ring and check the cooling water pipe at the same time;
5) Check the switch at the fishing line pendant, check whether there is scrap steel in the guide of the finishing mill. If there is any, it means that the previous one has piled steel in the finishing mill, and reset the roll gap in the finishing mill.
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