How much do you know about cold rolling work roll annealing and heat treatment quality inspection and some common defects?

Cold rolling rolls must have the ability to resist cracking and spalling caused by bending, torsion, and shear stress, and must also have high wear resistance, contact fatigue strength, fracture toughness, and thermal shock strength. Cold rolling work rolls are widely used, and the quality requirements for cold rolling work rolls are also very strict. Therefore, it is necessary to understand the quality inspection and some common defects of cold rolling work rolls.

Generally, only ultrasonic flaw detection is performed after heat treatment of cold rolling work rolls after forging, and sometimes a hammer Brinell hardness tester is used to randomly check the hardness. After quenching and tempering, the hardness of the roll necks at both ends is checked along two symmetrical busbars. Each busbar is no less than two measuring point. After the final heat treatment, a visual appearance inspection is performed first, followed by a roll body hardness inspection. When the roller body diameter is ≤300mm, check two busbars. When the diameter is >300mm, check four busbars. The distance between two adjacent points on each busbar should be approximately equal. When the roller body length is ≥1200mm, it should not exceed 200mm. <1200mm should not exceed 150mm, and the number of measurement points on each bus line should not be less than 4 points, and a Shore hardness tester should be used for measurement.

During heat treatment, some common defects will inevitably occur. What are the causes of these defects? What are the solutions?

Defect 1: The soft belt at the upper end of the roller body is too wide. The reasons for this defect and how to prevent it are as follows:

1. The sensor stop position is too low. Increase the sensor control position.

2. The sensor power outage occurs too early. Increase the sensor power outage position.

Defect 2: The soft belt at the lower end of the roller body is too wide. What is the reason for this?

1. The water supply is too late. Just spray water in advance.

2. The starting position of the sensor is too high. We should lower the starting position of the sensor.

Defect 3: Low hardness, the causes and prevention measures are as follows:

1. The quenching water pressure is low and the water volume is not enough. We need to find ways to increase the water pressure and quantity.

2. The quenching temperature is low. We can increase the quenching temperature by adjusting the voltage or mechanical parameters.

Defect 4: The upper edge of the roller body falls off

1. You can avoid falling off by adding a protective ring.

2. The sensor power outage is too late, lower the sensor power outage position.

3. The sensor stop position is too high, lower the sensor stop position.

Defect 5: Uneven hardness. Why does this defect occur?

1. The sensor and sprinkler are not aligned. We should adjust the position of the sensor and sprinkler before heating.

2. The sprinkler reverses water, reduce the water pressure, and change the angle of the sprinkler to solve this defect.

After reading these tips to prevent heat treatment defects, you don’t have to worry about it in the future heat treatment process. These are just some of the tips we tell you. We have more tips waiting for you and waving to you.