Method for measuring the surface temperature of a metal object

Claim 3

The method according to claim 1 wherein said step of correlating the radiant output of said hot plate with said reflected radiant heat comprises: determining the reflectance ( gamma ) of said metal surface at the area irradiated by said hot plate; and then determining the emissivity ( epsilon ) in accordance with the equation epsilon 1.0 - gamma .

Claim 4

A method according to claim 2 wherein the reflectance of said metal surface is determined in accordance with the equation gamma V/V1, where V is the radiant heat reflected from said surface, and V1 is the radiant heat emitted by said hot plate.

Claim 5

A method according to claim 1 wherein said step of correcting said temperature measurement comprises correcting said temperature measurement, the correction being a function of the determined value of emissivity.

Claim 6

A method according to claim 4 wherein said temperature correction is a function of the determined value of emissivity.

Claim 7

Apparatus for measuring the surface temperature of a metal object comprising: a radiation thermometer for measuring the temperature of the metal object at a high temperature point of said metal object; a radiation source hot plate having a surface emissivity close to unity located opposite to the surface of the metal object which is to be measured and radiating heat at an area of the surface of the metal object which is at a temperature considerably lower than the area of the surface of the metal object whose temperature is being measured by the radiation thermometer; means for maintaining the temperature of said hot plate substantially constant and considerably hotter than the area of the metal surface which is irradiated by said hot plate; means for measuring the radiant heat reflected by said metal surface from the area of irradiation by said hot plate; means for correlating the radiant output of said hot plate with said reflected radiant heat and for determining the emissivity of said metal surface as a function of siad radiant output and said reflected radiant heat; and means responsive to said determined emissivity of said metal surface and to the output of said radiation thermometer for generating a corrected value of temperature which corresponds to the surface temperature of said metal object at said high temperature point.

Claim 8

Apparatus for measuring the surface temperature of a metal object comprising: a radiation thermometer for measuring the temperature of the metal object at a high temperature point of said metal object; a radiation source hot plate having a surface emissivity close to unity located opposite to the surface of the metal object which is to be measured and radiating heat at an area of the surface of the metal object which is at a temperature considerably lower than the area of the surface of the metal object whose temperature is being measured by the radiation thermometer; means for maintaining the temperature of said hot plate substantially constant and considerably hotter than the area of the metal surface which is irradiated by said hot plate; means for measuring the radiant heat reflected by said metal surface from the area of irradiation by said hot plate; means for correlating the radiant output of said hot plate with said reflected radiant heat and for determining the emissivity of said metal surface as a function of siad radiant output and said reflected radiant heat; and means responsive to said determined emissivity of said metal surface and to the output of said radiation thermometer for generating a corrected value of temperature which corresponds to the surface temperature of said metal object at said high temperature point.

Claim 9

Apparatus according to claim 6 wherein said hot plate is arranged relative to said metal surface such that a solid angle theta observed from a point of radiation on said metal surface lies within a range pi < theta < 2 pi .

Claim 10

Apparatus according to claim 6 wherein said correlating means includes means for determining the reflectance gamma of said metal surface at the area irradiated by said hot plate, and means for determining the emissivity ( epsilon ) in accordance with the equation epsilon 1.0 - gamma .

Claim 11

Apparatus according to claim 8 wherein said means for determining the reflectance of said metal surface includes means for determining the ratio V/V1, where V is the radiant heat reflected from said surface and V1 is the radiant heat emitted by said hot plate, the reflectance being given by the equation gamma V/V1.

Claim 12

Apparatus according to claim 6 wherein said means for generating a corrected value of temperature includes means for varying the temperature measurement from said radiation thermometer in proportion to the value of emissivity determined by said correlating means.

Claim 13

Apparatus according to claim 10 wherein said temperature correction is a linear function of the determined value of emissivity.

Claim 14

Apparatus according to claim 6 wherein said hot plate is inclined relative to the surface of said metal object.

Claim 15

Apparatus according to claim 6 wherein said hot plate is substantially parallel to said metal surface.

Claim 16

Apparatus according to claim 13 wherein said hot plate includes an opening therein through which said radiant heat reflected by said metal surface is measured by said reflected radiant heat measuring means.