JPS57146461A - Roll for dual centrifugal casting - Google Patents

Abstract

PURPOSE:To relieve the excessive tensile stresses generated in the outer layer of a roll for the dual centrifugal casting, and to prevent cracking by forming the outer layer of said roll of Nihard cast iron and the inner layer of spheroidal graphite cast iron less than the tickness of the outer layer. CONSTITUTION:The reason for setting the thickness (t) of an inner layer 12 of the spheroidal graphite cast iron smaller than the thickness T of an outer layer 11 of Nihard cast iron lies in that while the thermal expansion of the spheroidal graphite used for the layer 12 is similar to that of conventional FC 20, the ealstic modulus is large as compared to FC 20 and that if a difference in the rates of thermal expansion is produced between the layers 11 and 12 excessive tensile stresses are generated in the layer 11 and these can be relieved by making the layer 12 thinner than the layer 11. Now, when the layer 11 is more contracted than the layer 12, the layer 11 is pulled and the layer 12 is compressed. If the difference in the radii of the layers 11, and 12 is about the same, the tensile force acting upon the layer 11 and the compressive force acting upon the inner layer are the same. Since the stress leading to failure corresponds to this force divided by the thickness, the stress of the layer 11 of thick thickness is made smaller than the stress of the thin layer 12.