This invention relates to a temperature data producing apparatus for noncontact measuring of the temperature of a high temperature moving object such as a naturally falling melted metal droplet.
When metal material, particularly, metals having a high melting point such as niobium, molybdenum and tungsten or active metals such as titanium and zircon are melted in the air, impurities such as oxides and nitrides are formed inside the metals, thus greatly degrading the various characteristics of each metal. This same phenomenon occurs in super alloys such as corrosion and heat resistant alloys. In order to produce high quality ingots, it is necessary to remelt these metals in a vacuum chamber, to eliminate the impurities such as hydrogen, oxygen, nitrogen, tin and lead by exposure to the vacuum. This remelted metal is dropped into a mold that does not react chemically with the remelted metal where it solidifies into an ingot. To make the metal drop into the mold, it is heated with an electric arc, plasma or electron beam to melt it. Copper molds with water cooled surfaces are often used.
It is known that the temperature of the remelted alloy droplets is an important factor in determining the surface quality such as the ingot surface smoothness and the internal quality, which represents the macro structure and the compositional segregation of the solidified alloy in the mold.
However, the naturally falling melted metal droplets are very small having a diameter of 5-15 mm, fall with the acceleration of gravity, and are in a vacuum chamber, making accurate measurement of the temperature an impossibility. It is consequently impossible to control the temperature of the droplets and very difficult to obtain ingots of high quality. This is the same for pure metals such as niobium, molybdenum and tungsten.