铸铁烘缸常见缺陷成因分析及在线检测

On-line Testing of the Defects of Paper Machine Cast Iron Dryer

在对3400余台铸铁烘缸检测研究的基础上,提出了基于纵波双晶探头的铸铁烘缸超声波检测技术。通过对铸铁烘缸筒体和小R过渡区的气孔、缩孔、夹杂采用纵波双晶小角度探头(5°)检测,发现体积型缺陷;对铸铁烘缸筒体和小R过渡区裂纹采用纵波双晶较大角度探头(42°)检测,发现深裂纹类平面缺陷。解决了在线检测中铸铁烘缸常规检测项目测厚值强度计算或与设计对比的问题、对硬度值偏小的判定问题、在线检测重点部位的确定问题、对含小尺寸裂纹缺陷铸铁烘缸安全运行评估的确定问题,从而成功解决了在用铸铁烘缸检测的难题。

Based on more than 3,400 tests on cast iron dryers in Hangzhou area,an ultrasonic testing technic with longitudinal wave double-crystal probe was established.With this technic the volume defects were identified through testing the air holes,shrinkage cavities and inclusions in the dryer cylinder and small R transition zone with longitudinal wave double crystal probe at a small angle（5°）,and the plane defects of deep cracks were found through testing the dryer cylinder and small R transition zone with longitudinal wave double crystal probe at a large angle（42°）.It provided the solution to the issues of how to use the thickness measurement in regular online testing cast iron dryers to calculate their strength or compare with the design value,how to adjudge the low hardness value,how to determine the key parts foe online testing,how to conduct safety assessment of the cast iron dryers with small cracks.