Cause Analysis and Prevention of Roll Ring Collapse

Roll material: nickel-chromium-molybdenum infinite chilled centrifugal composite III

Roller body specification: ¢395*700mm

Types of rolled products: ¢25mm rebar

Use rack: K1

Objection form description: In the first cycle of use, the roll ring collapsed during the rolling process, and the surface of the rolling groove was partially blue and shiny.

Cause Analysis:

1. The cooling effect during the rolling process is not good, which causes the rolling products to wear a lot of the rolling grooves and is prone to fatigue cracks.

2. The pass design is unreasonable and the width of the roller ring is narrow, which reduces the strength and bearing capacity of the roller ring.

3. After the roll pass is processed, there is no effective protection, so that the rolls collide with each other or collide with other objects, so that the roll ring is damaged.

Preventive corrective measures:

1. Increase the amount of cooling water, reduce the water temperature and improve the water quality to ensure a good cooling effect during the rolling process.

2. Reasonably design the hole pattern to ensure that the width of the roller ring meets the requirements.

3. The rolls should not be stacked straight on the ground after the holes are cut. They should be placed on two sleepers (cross-sectional area) ≥ 15cm2, and covered with the blankets removed from the roll packaging to prevent the rolls from being damp, corroded and collided.

Roll material: nickel-chromium-molybdenum infinite chilled centrifugal composite III

Roller body specification: ¢352*600mm

Types of rolled products: ¢14mm rebar

Use rack: K1

Objection form description: In the first cycle of use, small pieces appear on the edge of the roll ring (the crescent cusp) during the rolling process, and each pass appears. As shown

carbide roll rings

Cause Analysis:

The main reason for similar roll ring dropout is the unreasonable hole design, as follows:

1. The crescent is processed to the edge of the hole, reducing the bearing capacity of the edge of the roller ring.

2. The tangent R of the edge of the pass is too small, and the force on the edge of the roll ring is concentrated, causing the roll ring to fall off after the impact force and extrusion force of the rolled product.

Preventive corrective measures:

Reasonably design the roll pass, prevent the crescent to be processed to the edge of the pass, increase the tangent R of the edge of the pass, and disperse the force on the edge of the roll ring.

Roll material: nickel-chromium-molybdenum infinite chilled centrifugal composite III

Roller body specification: ¢295*500mm

Types of rolled products: ¢10mm rebar

Use rack: K1

Description of objection form: In the third cycle of use, the roll ring collapsed during the rolling process, and there were multiple collapses on the same surface.

Cause Analysis:

1. After the roll pass is processed, the roll is not well maintained, which causes the roll to be damp, corroded or collided on one side, which affects the quality of the roll.

2. The pass design is unreasonable, the rolling reduction of the K1 frame is too large, the steel bar is ground to the front of the roll ring, and the force of the roll ring is increased.

3. The fatigue crack is not completely eradicated when the roll is repairing the pass pattern, and the block collapses with the extension of the crack.

Preventive corrective measures:

1. The rolls should not be stacked straight on the ground after the holes are cut. They should be placed on two sleepers (cross-sectional area) ≥ 15cm2, and covered with the blankets removed from the roll packaging to prevent the rolls from being damp, corroded and collided.

2. Reasonably design the pass type to ensure that the reduction of each rack meets the requirements of the rolling process.

3. Use the rolls reasonably, repair the roll pass pattern according to the cycle, and eradicate the fatigue cracks generated during the rolling process for each repair, and the fatigue cracks cannot be extended indefinitely.

 

Roll material: nickel-chromium-molybdenum infinite chilled centrifugal composite III
Roller body specification: ¢335*600mm
Types of rolled products: ¢12mm rebar
Use rack: K1
Description of objection form: In the first cycle of use, there are many roll ring collapse blocks during the rolling process, and the partial color of the roll surface is light blue, as shown in Figure 18.
Cause Analysis:
1. During the rolling process, the cooling quality is not good, the water temperature is high, the water volume is insufficient or the flushing position is not in place, which causes the cooling effect to be poor. The rolling product wears the rolling groove greatly and is prone to fatigue cracks, and the crack extension leads to block drop.
2. The hardness of the roll is too high, which increases the tendency of cracks and block drop during the rolling process. The toughness and strength fail to meet the rolling conditions, causing cracks and block drop.
Preventive corrective measures:
1. Increase the amount of cooling water, reduce the water temperature and improve the water quality, ensure a good cooling effect during the rolling process, and reduce the wear and fatigue cracks of the rolling products on the rolling groove.
2. Reduce the hardness of rolls of the same material, increase toughness and strength, or replace rolls with higher toughness and strength to meet the rolling conditions.

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