Effect of laser quenching process on surface hardness and wear performance of wheat grinder roller

Objective  To study properties of surface material of wheat grinder roller after laser quenching, and solve the problems of grinding roller such as serious wear and short service life.

Method  Using the principle of rotating combination design of response surface, a mathematical model of laser power, spot diameter and scanning speed with surface hardness of grinding roller material was established according to three-factor and five-level test method. The effects of laser power, scanning speed, spot diameter and reciprocal action among three factors on grinding roller surface hardness were analyzed. The optimal parameter combination was obtained. The wear mechanism of surface material of the grinding roller after quenching was investigated.

Result  Laser power, spot diameter and scanning speed significantly affected surface hardness of grinding roller material. The effects of laser power, spot diameter and scanning speed on surface hardness of grinding roller material weakened successively. The optimal technological parameter combination was laser power 190 W, spot diameter 0.70 mm and scanning speed 220 mm/s and the sample surface hardness obtained was 688.67 HV, which was 35% higher than original hardness. The mass loss of sample treated by optimal laser quenching parameter combination in wear process was about 7% of the untreated sample. The friction between grinding roller surface material and wheat powder material after laser quenching weakened. The scratches of wheat powder material on sample surface were lighter and shorter. The grooves were shallower and narrower.

Conclusion  The wear resistance against wheat powder material of grinding roller surface material is obviously enhanced after laser quenching treatment.