Detection of flaws in metal members

Abstract

A method of detecting flaws in metal members is disclosed. The metal member is exposed to high frequency heating whereupon the temperature profile across the work piece is measured, preferably by recording with an infrared camera. The recorded data can be used for automatic marking or repair of the metal member.

What is claimed is: 
     
       1. A method of detecting surface flaws is a non-magnetic metallic workpiece comprising: (a) heating said non-magnetic metallic workpiece by passing said workpiece through an induction heater for induction heating with a high frequency current;   (b) scanning said non-magnetic metallic workpiece with an infrared camera to determine a temperature profile of the scanned portion of said non-magnetic metallic workpiece within 3 seconds of the time of heating;   (c) generating an output signal in said first infrared camera corresponding to said temperature profile;   (d) feeding said output signal to a data processor which controls a grinding apparatus for automatically grinding said workpiece in accordance with said temperature profile;   (e) reheating said non-magnetic metallic workpiece by passing it through a second induction heater;   (f) scanning said non-magnetic workpiece with a second infrared camera to determine a new temperature profile;   (g) generating a correction signal corresponding to said new temperature profile; and   (h) feeding said correction signal to said data processor to automatically adjust the grinding apparatus. .Iadd.   
     
     
       2.  A method for detecting flaws in a surface of a metallic workpiece selected from the group consisting of metal blooms and metal billets by means of an induction heater and a single infrared camera without coating said surface to increase the emission of heat therefrom which comprises: (a) heating said metallic workpiece by moving said workpiece in one direction through said induction heater which generates a high frequency current that heats the workpiece;   (b) scanning said uncoated surface of said workpiece with said single infrared camera transversely across the surface of said moving workpiece immediately after induction heating and within not more than two seconds of the time of heating and recording a streaked pattern temperature profile in which the streaked pattern repeats itself where there are flaws in the surface of said metallic workpiece; and   (c) generating an output signal from said infrared camera corresponding to said recorded streaked pattern temperature profile to determine the location, size, shape and depth of flaws in the surface of said workpiece from said streaked pattern. .Iaddend. .Iadd.   
     
     
       3.  A method for detecting flaws in a surface of a metallic workpiece selected from the group consisting of metal blooms and metal billets by means of an induction heater and a single infrared camera which comprises: (a) heating said metallic workpiece by moving said workpiece in one direction through said induction heater for induction heating by generating a high frequency current;   (b) scanning said surface of said workpiece with said single infrared camera transversely across the surface of said moving workpiece immediately after induction heating and within not more than two seconds of the time of heating and recording a streaked pattern temperature profile in which the streaked pattern repeats itself where there are flaws in the surface of said metallic workpiece;   (c) generating an output signal from said infrared camera corresponding to said recorded streaked pattern temperature profile for determining the location, size, shape and depth of flaws in the surface of said workpiece from said streaked pattern; and   (d) recording a hard copy of said streaked pattern temperature profile from the output signal of said infrared camera which determines the location, size, shape and depth of flaws in the surface of said workpiece. .Iaddend. .Iadd.   
     
     
       4.  A method for detecting flaws in a surface of a metallic workpiece selected from the group consisting of metal blooms and metal billets by means of an induction heater, a single infrared camera and a data processor which controls a marking pen which comprises: (a) heating said metallic workpiece by moving said workpiece in one direction through said induction heater for induction heating by generating a high frequency current;   (b) scanning said surface of said workpiece with said single infrared camera transversely across the surface of said moving workpiece immediately after induction heating and within not more than two seconds of the time of heating and recording a streaked pattern temperature profile in which the streaked pattern repeats itself where there are flaws in the surface of said metallic workpiece;   (c) generating an output signal from said infrared camera corresponding to said recorded streaked pattern temperature profile to determine the location, size, shape and depth of flaws in the surface of said workpiece from said streaked pattern; and   (d) feeding said output signal from said camera to said data processor to control said marking pen for automatically marking the surface of said workpiece with the location, size and shape of surface flaws in accordance with the streaked pattern of said temperature profile. .Iaddend. .Iadd.5. A method for detecting flaws in a surface of a metallic workpiece selected from the group consisting of metal blooms and metal billets by means of an induction heater, a single infrared camera and a data processor which controls grinding apparatus which comprises:   (a) heating said metallic workpiece by moving said workpiece in one direction through said induction heater for induction heating by generating a high frequency current;   (b) scanning said surface of said workpiece with said single infrared camera transversely across the surface of said moving workpiece immediately after induction heating and within not more than two seconds of the time of heating and recording a streaked pattern temperature profile in which the streaked pattern repeats itself where there are flaws in the surface of said metallic workpiece;   (c) generating an output signal from said infrared camera corresponding to said recorded streaked pattern temperature profile to determine the location, size, shape and depth of flaws in the surface of said workpiece from said streaked pattern;   (d) feeding said output signal of said infrared camera to said data processor to control said grinding apparatus for automatically grinding the surface of said workpiece in accordance with the streaked pattern of said temperature profile to remove surface flaws therefrom;   (e) reheating said workpiece after said grinding by moving it through a second induction heater in one direction for induction heating with a high frequency current;   (f) scanning the surface of said workpiece with a second infrared camera transversely across the surface of said moving workpiece immediately after induction heating and within not more than two seconds of the time of heating and recording a second new streaked pattern temperature profile in which the streaked pattern repeats itself where there are flaws in the surface of said workpiece;   (g) generating an output signal from said second infrared camera corresponding to said second streaked pattern temperature profile for determining the location, size, shape and depth of any remaining flaws in the surface of said workpiece; and   (h) feeding said output signal from said second camera to said data processor to generate a correction signal to automatically adjust the grinding operation for removing surface flaws. .Iaddend.