FORMING OF THE SQUARE-END DEFECT OF TUBE DURING Φ100mm PLUG PIPE MILL OPERATION AND COUNTERMEASURES

The paper presents an investigation into the elements responsible for formation of the squareend defect of tube during the Φ100 mm plug pipe mill operation, The result shows that the said defect is caused by such elements as over rear-positioned plug bar, radial vibration of the roll and over-big ovality factor during shell deformation under piercing, etc, Accordingly countermeasures are proposed.