Common Accidents on the Site of High-speed Steel Rolling and Measures (2)

5. What are the reasons for holding back the steel during rolling?

(1) Defects caused by the billet itself, such as inclusions, delamination, severe bubbles, etc., are rolled to half during the rolling process, causing cracking and holding the steel;

(2) When the speed of the certain intermediate rolling mill is set improperly, the steel rolling state is actually produced. The first half of the rolled piece is maintained by the front rolling mill to maintain tension rolling. When the tail of the rolled piece leaves the front rolling mill, the tension suddenly loses there, causing the holding back of steel;

(3) It is caused by the sudden increase or decrease of the speed of the motor of a rolling mill, which destroys the original continuous rolling relationship;

(4) Due to the sudden breakage of the roll or the severe damage of the guide in the previous passes, the cross-section of the rolled piece is changed and the steel is held.

Measures: ① Strengthen the picking of raw materials, strengthen the inspection of steel rolling, and take timely measures;

② Eliminate excessive tension;

③ Notify electrical treatment;

④ Regularly shut down to check the wear of the rolling guide to avoid holding back the steel.

6. Adjustment of the intermediate rolling mill unit: When adjusting the material type, you must first pay attention to the state of the stacking steel between the two rolling mills, and then adjust the ellipse material type. You must pay attention to whether the input splint is seriously worn.

7. Heavy iron hitting at the outlet of the rough and medium rolling mill:

(1). The front frame round hole material is too full or the input guide wears seriously (With severe scratches).

(2). The material type of this frame is inappropriate and too large.

(3). Change the exit guide.

8. Pre-finishing rolling mill: (1) 14 output is seriously ironed: the incoming material is too large, the amount of reduction is too large; the material shape is wide; the inner wall of the exit guide is not smooth, and the grinding is not good.

(2) 15 input is severely ironed: 14 outlets are worn and the torsion angle is not suitable; 15 inlet guide guard gaps are not suitable or severely worn and cannot support the steel;

(3) 15 input guide roller: the input guide is not installed correctly, and the incoming material hits the single-side guide roller when biting; the guide gap is not suitable, too tight; the guide roller is not cooled.

9. 17, 19 guide guard hit iron:

Measures: The guide gap is small, and press the 16, 18 material to re-find the tension.

10. Pre-finishing rolling leaving tail

Reasons: Tension before continuous finishing (continuous adjustment), the material shape is not good.

Measures: After pressing the material to the standard value, adjust the tension again; the delay time of the looper is not suitable; the height of the looper is not suitable.

11. 3# Shear steel pile

(1) Head pile steel

Reason: cutting head of 3# is too short, bring the head into 7 sets; 3# shear is without the head.

Measures: Lengthen the cutting head of 3# shear.

(2) Steel pile in the middle or tail

Reason: The pre-finishing rolling speed is set too high continuously.

Measures: adjustment to reduce pre-finishing 5 consecutive adjustments.

More Articles You May Be Interested:

1. The Main Factors Affecting the Quality of the Wire Rod 

2. How to Improve the Assembly Quality of the Roller Box of the Wire Rod Mill?

3. Process Adjustment of Wire Rod Mill

4. Technical Requirements of Rolls and Reasons for Broken Rolls 

5. Finishing Mill Roll Assembly Technology

6. The Practice of Direct Rolling without Heating

Common Accidents on the Site of High-speed Steel Rolling and Measures (1)

1. Jamming of steel

Reasons: ① The roll gap on both sides of the roll is inconsistent.

② The gap of the input box is severely worn, the gap is too large.

③ The axially fixed pressing block of the roll is not fastened, which causes roll error in rolling.

④ Incoming materials are out of square or severely reversed.

⑤ Long-term wear of the hole type is on the left or right side.

Measures: ① Adjust roll gap;

② Replace the input box;

③ Tighten the axial fixed pressure block to eliminate the roller error;

④ Remove the raw materials with serious detachment;

⑤ Change the slot.

2. Rolled piece do not bite

Reasons: ① The reduction is too large;

② The grinding groove is not good or there are water and oil on the surface of the groove;

③ The sliding plate on the inner side of the card-breaking shear is not welded or moved laterally;

④ The head of the incoming material is off square or has a large deformation during cutting, and it is stuck in the input box.

Measures: ① Reduce the reduction of this pass, enlarge the roll gap appropriately, and then press back to the normal range after normal rolling, the billet head is cut into a wedge or cone shape, when changing the roll or groove (When the rolling stop time is sufficient), press the head of the billet a little bit in advance, stop the machine and then go out of the rolling mill and return to the heating furnace to reheat.

② Grind the grooves in place to increase the surface roughness of the grooves and remove oil stains;

③ Check the shearing machine and rolling mill processing;

④ Remove the raw materials with severe head deformation or cutting.

3. Rough and medium-rolled slipping steel

Reasons: ① The reduction is too large;

② The grinding groove is not in place;

③ Turn on the cooling water in advance;

④ There is oil on the surface of the groove;

⑤ The gap between input guides is small;

⑥ The speed of the front frame has not been reduced (2.5% ～ 3%) just after the rolling.

Measures: ① Properly enlarge the roll gap and press it back to the normal range after normal rolling;

② Grinding groove in place;

③ Avoid turning on the cooling water in advance;

④ Remove the oil stain on the surface of the rolling groove;

⑤ Check the gap between the input guides;

⑥ Slow down after changing the roller and groove.

4. Head rolling steel during rolling

Reasons: ① The size of the rolled product in the previous pass is too large, so that when the rolled product enters the next pass, it is squeezed in the entrance guide plate to cause suffocation;

② Due to the uneven deformation of the billet head during rolling, the temperature of the billet head is low may cause the steel to split;

③ The rolling guide is seriously worn, the guide roller does not rotate, and the guide roller arm is loose, which causes the guide roller gap to change, causing steel holdback;

④The elbow of the rolled piece does not lead to the next lane, causing steel holdback.

Measures: ① Adjust the material type;

② Avoid low-temperature steel, pay attention to the condition of the billet head and avoid splitting the head;

③ Regular shut down to check the input and output guide to avoid holding back the steel;

④ Avoid elbows;

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