METHOD FOR MEASURING MELTED DEPTH OF CAST STEEL BILLET, AND METHOD FOR SURFACE TREATMENT OF CAST STEEL BILLET

摘要

PROBLEM TO BE SOLVED: To measure the melted depth of a cast steel billet during the melting treatment for the surface of the cast steel billet by plasma gas.

SOLUTION: When the surface of the cast billet H is heated and melted by plasma gas radiated from a plasma torch T1 while moving the cast billet H in the carrying direction B, a recess Z is formed by discharging molten metal Q from the melted portion by adjusting the flow rate of the plasma gas. Then, a laser spot S having the luminance higher than that of the plasma arc P is formed by irradiating the central portion of the recess Z with a laser beam by means of a laser radiating device 32. Then, the variation of the displacement of the laser spot S in the vertical direction is measured. The melted depth L can be measured by the vertical displacement of the laser spot S when the magnitude of the variation of the displacement has become smaller than a required value.

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