加热炉步进梁连杆故障诊断与损伤机理

Fault diagnosis and damage mechanism of walking beam in reheating furnace

加热炉连杆焊接位置开裂是热轧生产线加热炉步进梁升降工作过程中频繁发生的现象,为了诊断开裂原因及分析断裂机理,首先对步进梁连杆进行服役状态下的贴片测试,绘制出加热炉满负荷状态下连杆的应力变化情况及过程;之后结合测试数据与钢坯统计数据,做出了开裂部位的载荷谱并据此完成了杆件的疲劳分析。结果表明:故障频发的加热炉杆件满足设计的疲劳寿命,之所以断裂是因为同步轴铰接轴承承受了额外的附加弯矩,其使得连杆附加弯矩加大。设法提高铰接轴承处的润滑状况能够明显改善连杆的受力状态;与此同时,在连杆与同步轴铰接轴承位置附近增加焊接筋板,也可以显著提高连杆抗弯曲变形的能力,降低连杆开裂几率。

The connecting rod cracking and fracture phenomenon occurs frequently in the heating furnace in the step beam lifting work process. Its fault reason and fracture mechanism were analyzed. The patch test for the heating furnace connecting rod of walking beam under the service condition was carried out and the full load service during the process after change of the force was obtained. According to the test data and the statistical data of the history of the machine factory production of steel varieties,the load spectrum of the rod was made to complete the analysis of fatigue. The calculation results show that the service furnace satisfies the fatigue life of the design,and the fracture is due to the additional bending moment of the hinged bearing of the synchronous shaft,which results in the increase of the additional bending moment of the connecting rod. The hinge bearing stress state can be improved by improving the lubrication condition of connecting rod. Meanwhile,the ability of the bending deformation of the connecting rod can be significantly increased by the reinforcing plates near the connecting rod.