1. Roll material: Nickel-chromium-molybdenum nodular graphite infinite chill Ⅰ
Roller body specification: ￠390*750mm
Types of rolled products: ￠12-16mm rebar
Use rack: K9
Description of objection form: During the first cycle of use, there was a break from the middle of the roll body during the rolling process, the fracture was straight, the macrostructure was coarse and radial, the surface of the roll body was normal in color, and there was no injury. As shown.
Cause Analysis:
The fracture of the roll is straight, the macrostructure is coarse and radial, and the roll body is broken due to the low strength of the roll and the failure to meet the rolling requirements.
Preventive corrective measures:
Enhance the strength of the roll, improve the quality of the roll, and meet the rolling requirements.
2. Roll material: chrome molybdenum ductile ink infinite chill
Roller body specification: ￠450*1000mm
Types of rolled products: ￠6.5-8mm wire rod
Use rack: K23
Description of objection form: In the second cycle of use, the roll body breaks during the rolling process, the core of the section protrudes, the macroscopic structure is fine, and the section has a darker layer of blue color.
Cause Analysis:
1. After the roll body is broken, the cross-section obviously has a darker layer of blue color, which is due to the poor cooling effect during the rolling process. The temperature of the roll is not effectively cooled after the thermal shock, causing the roll body to be injured. Body strength is reduced.
2. During the rolling process, the roll is subjected to excessive thermal shock force and twisting force, which causes the instantaneous reduction between the roll gaps to increase, and the excessive torque leads to the breakage of the roll. Based on the above analysis, the main reasons for the breakage of the roll body are poor cooling effect during the rolling process, low rolling product temperature, excessive reduction, thermal shock, and twisting force on the roll.
Preventive corrective measures:
1. Improve the quality of cooling water, increase the amount and pressure of cooling water, and reduce the water temperature to ensure a good cooling effect during the rolling process.
2. During the rolling process, strictly follow the rolling process and operating procedures, control the temperature of the rolled products, and prevent the occurrence of jamming or low-temperature rolling, which will affect the service life of the rolls.
