Causes of hearth roll breakage and follow-up treatment
The roller hearth heat treatment furnace is the standard configuration of the medium and heavy plate heat treatment production line. The condition of the furnace hearth roller directly affects the appearance and quality of the steel plate. The hearth roll sometimes breaks during production.
The reasons for the broken roll of the hearth roll are:
1) Processing quality
For the appearance quality and outer diameter size, the processing factory generally performs turning processing at the welding junction. The large thickness of turning will cause the edge of the machined surface and the non-machined surface of the journal to be chamfered, and the chamfered part will produce a stress concentration area. If it is too large, roller breakage will occur.
2) heating and cooling
In addition, the fit between the roll body and the roll neck welding part is a gap fit, and it is easy to accelerate the roll body and the roll neck welding part to produce cracks after frequent heating and cooling, and eventually break.
In the production, the bottom rolls sometimes have problems of bending and broken rolls. The broken rolls mainly occur in the preheating section and heating section of the furnace. The main parts of the broken rolls are the shaft head, the journal and the roll body. The occurrence of roll breakage will affect the production of thick plates, and at the same time, it is easy to cause safety accidents.
Treatment of hearth roll broken roll:
Cancel or reduce the turning process at the weld, or increase the thickness of the roll body to enhance the overall strength of the joint part; improve the matching size of the roll body and the roll neck, so that the roll body and the roll neck are closely combined. The temperature rises strictly according to the oven curve, and the furnace bottom roller is cooled with the furnace when the furnace is stopped, so as to reduce the influence of temperature change. In addition, defective hearth rolls should be replaced in time.
