| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for removing excess scale from a plug for piercing a seamless steel tube material, which enable the occurrence of flaws in a tube inner surface to be advantageously prevented, the occurrence of the flaws being caused by scale peeled from the plug upon piercing rolling, and a method of using the plug.SOLUTION: A method for removing excess scale is provided in which jet water 3 from a nozzle 2 is sprayed to a treatment object material 1 that is a plug having an oxide scale film, while rotating the plug around the plug center axis 1A, under the jet condition that the jet pressure is 15 MPa or more and 80 MPa or less, and that the kinetic energy E (J/mm) of jet water defined by expression (1) and received by the treatment object material is 20-1500 J/mm. E=Q×P×t/(D×π×W×ρ×60)...(1)[Q is jet flow rate (L/min), P is jet pressure (Pa), t is jet time (sec), D is the diameter (mm) of the plug being the treatment object material, W is nozzle jet width (mm), π is circumference ratio (=3.14), ρ is jet water density (kg/m)]SELECTED DRAWING: Figure 1 |
