USRE32166E - Detection of flaws in metal members - Google Patents

Detection of flaws in metal members Download PDF

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Publication number
USRE32166E
USRE32166E US06/597,207 US59720784A USRE32166E US RE32166 E USRE32166 E US RE32166E US 59720784 A US59720784 A US 59720784A US RE32166 E USRE32166 E US RE32166E
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Prior art keywords
workpiece
flaws
infrared camera
temperature profile
streaked pattern
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US06/597,207
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Arnulf Berge
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Elkem ASA
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Elkem ASA
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Priority claimed from US06/001,460 external-priority patent/US4247306A/en
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Priority to US06/597,207 priority Critical patent/USRE32166E/en
Assigned to ELKEM A/S reassignment ELKEM A/S CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE DATE : SEPTEMBER 02, 1980 Assignors: ELKEM-SPIGERVERKET A/S
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/72—Investigating presence of flaws
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B47/00—Drives or gearings; Equipment therefor
    • B24B47/22—Equipment for exact control of the position of the grinding tool or work at the start of the grinding operation

Definitions

  • the present invention relates to a method for flaw detection for metal members and, in particular, metal blooms or billets such as of steel, aluminum or the like.
  • One method used for detecting surface flaws involves the use of a magnetic field.
  • Surface flaws are initially filled with air, slag, oxides or the like, as a result of which the surface flaws, and notably cracks, will have a poorer magnetic conductivity than the rest of the work piece. There is thereby obtained a strong magnetic field in a direction transverse to the cracks and this strong magnetic field can be detected to indicate surface flaws.
  • a fluorescent magnetic powder is distributed on the surface of the work piece.
  • the powder will tend to collect to a greater degree in the surface flaws which can then be exposed by ultraviolet light.
  • the work piece is magnetized by passing a current through it, after which it is covered with a magnetically attractable powder including a coloring agent which will melt and adhere to the billet upon heating.
  • the metal object in then heated to a sufficient intensity to cause the coloring agent to adhere and, because of the stronger magnetic attraction at the cracks, it will show up the most at these locations.
  • FIGURE shows a schematic of an apparatus which can be used in the present invention.
  • FIG. 1 In the FIGURE is shown a track 10, along which a billet 12 is progressing in the direction of the arrow as indicated thereon.
  • the billet passes through an induction heater 14 which operates at high frequency, preferably above about 10,000 hertz.
  • an infrared thermo-camera 16 Positioned immediately downstream from the induction heater 14 is an infrared thermo-camera 16 which scans the work piece and forms a temperature profile. When the temperature across the work piece is measured, there will be found an increase in temperature adjacent surface irregularities, such as cracks. The temperature profile will form a streaked temperature pattern across the surface, and the surface irregularities will be indicated by the fact that the streaked pattern repeats itself.
  • the data obtained from the infrared camera can be recorded as a hard copy but is preferably fed directly to a data processor 18, which in turn controls downstream equipment 20, such as a marking pen or grinding equipment.
  • downstream equipment 20 such as a marking pen or grinding equipment.
  • the detected flaws can be automatically marked or they can be automatically ground out. Since the size, shape and depth of the crack will be discernible from the temperature profile, the exact grinding necessary to remove it can be determined by an appropriate program.
  • the treated billet can be subjected again to the flaw detection apparatus 14A, 16A to insure that the correct grinding has been effected and, by appropriate feed back of data to the data processor 18, adjustments in the grinder 20 can be automatically made.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials Using Thermal Means (AREA)

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.

Description

.Iadd.This application is a continuation of reissue application Ser. No. 386,440 filed June 6, 1982, now abandoned. .Iaddend.
The present application is a continuation-in-part of application Ser. No. 957,343, filed Nov. 3, 1978 now abandoned.
The present invention relates to a method for flaw detection for metal members and, in particular, metal blooms or billets such as of steel, aluminum or the like.
It is, of course, well known in the art that surface flaws occur in the formation of steel work pieces such as blooms or billets, and many different attempts have been made to detect these surface flaws for the purpose of eliminating them by grinding or the like. Indeed, many of these methods are in commercial use today and have proved to be quite successful. While successful, they unfortunately also have drawbacks.
One method used for detecting surface flaws involves the use of a magnetic field. Surface flaws are initially filled with air, slag, oxides or the like, as a result of which the surface flaws, and notably cracks, will have a poorer magnetic conductivity than the rest of the work piece. There is thereby obtained a strong magnetic field in a direction transverse to the cracks and this strong magnetic field can be detected to indicate surface flaws.
In yet another known method, a fluorescent magnetic powder is distributed on the surface of the work piece. The powder will tend to collect to a greater degree in the surface flaws which can then be exposed by ultraviolet light. In still another method, the work piece is magnetized by passing a current through it, after which it is covered with a magnetically attractable powder including a coloring agent which will melt and adhere to the billet upon heating. The metal object in then heated to a sufficient intensity to cause the coloring agent to adhere and, because of the stronger magnetic attraction at the cracks, it will show up the most at these locations. This process can be fully automatic and is described in U.S. Pat. No. 3,845,383.
Other methods for detecting surface flaws are also known and, in fact, the art is quite well developed. However, there are disadvantages to all of the known prior art processes. These involve one or more of a combination of the process not being automatic or using up relatively expensive materials, such as the magnetically attractable compositions, or being inaccurate, or requiring the application of a powder, dust or liquid which inherently creates an undesirable environmental condition.
The applicant has now discovered that all of the foregoing disadvantages of prior art processes can be overcome by the relatively simple expedient of employing high frequency heating and measuring the resulting temperature profile of the metal work piece, suitably by recording with an infrared camera. Surface flaws on blooms, billets and the like are characterized by sharp edges and other irregularities in the surface, and these become much hotter than the surrounding areas when subjected to high frequency inductive heating. Because of this great difference in temperature, a temperature profile can be developed which will pinpoint the location of the surface flaws.
Because of the high heat conductivity of metal materials, it is necessary to observe the temperature profile either during the high frequency heating or immediately thereafter, e.g., within no more than about 2-3 seconds. For achieving this result, an infrared camera has been found to be especially desirable. In fact, use of this apparatus permits the process to be made fully automatic, including the marking or subsequent grinding operation.
These and other features of the present invention may be more fully understood with reference to the FIGURE, which shows a schematic of an apparatus which can be used in the present invention.
In the FIGURE is shown a track 10, along which a billet 12 is progressing in the direction of the arrow as indicated thereon. In the picture as shown, the billet passes through an induction heater 14 which operates at high frequency, preferably above about 10,000 hertz. Positioned immediately downstream from the induction heater 14 is an infrared thermo-camera 16 which scans the work piece and forms a temperature profile. When the temperature across the work piece is measured, there will be found an increase in temperature adjacent surface irregularities, such as cracks. The temperature profile will form a streaked temperature pattern across the surface, and the surface irregularities will be indicated by the fact that the streaked pattern repeats itself. The data obtained from the infrared camera can be recorded as a hard copy but is preferably fed directly to a data processor 18, which in turn controls downstream equipment 20, such as a marking pen or grinding equipment. In this way, the detected flaws can be automatically marked or they can be automatically ground out. Since the size, shape and depth of the crack will be discernible from the temperature profile, the exact grinding necessary to remove it can be determined by an appropriate program. Obviously, the treated billet can be subjected again to the flaw detection apparatus 14A, 16A to insure that the correct grinding has been effected and, by appropriate feed back of data to the data processor 18, adjustments in the grinder 20 can be automatically made.
One of the most important advantages of the present invention, in addition to those hereinbefore delineated, is that the method can be used equally well with nonmagnetic metal work pieces. This is indeed a great advantage since the magnetic processes are totally unsuitable for use with non-ferrous materials, and these magnetic methods are the most widely used today.
It will be understood that the claims are intended to cover all changes and modifications of the preferred embodiments of the invention, herein chosen for the purpose of illustration, which do not constitute departures from the spirit and scope of the invention.

Claims (4)

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.
US06/597,207 1979-01-17 1984-04-06 Detection of flaws in metal members Expired - Lifetime USRE32166E (en)

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US06/001,460 US4247306A (en) 1979-01-17 1979-01-17 Detection of flaws in metal members
US06/597,207 USRE32166E (en) 1979-01-17 1984-04-06 Detection of flaws in metal members

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US06386440 Continuation 1982-06-06

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4826326A (en) 1986-09-17 1989-05-02 United Kingdom Atomic Energy Authority Crack sizing
EP0378006A1 (en) * 1989-01-10 1990-07-18 Elkem Technology A/S Method of flaw detection in billets
US5111048A (en) * 1990-09-27 1992-05-05 General Electric Company Apparatus and method for detecting fatigue cracks using infrared thermography
US5240329A (en) * 1992-08-14 1993-08-31 Ford Motor Company Non-destructive method for detecting defects in a workpiece
US5562345A (en) * 1992-05-05 1996-10-08 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method and apparatus for thermographically and quantitatively analyzing a structure for disbonds and/or inclusions
US20040089812A1 (en) * 2002-08-28 2004-05-13 Wayne State University System and method for multiple mode flexible excitation and acoustic chaos in sonic infrared imaging
US20040262521A1 (en) * 2003-06-30 2004-12-30 Devitt John William Methods for determining the depth of defects
US20060067378A1 (en) * 2004-09-29 2006-03-30 Rege Siddharth S Apparatus and method for thermal detection

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1869336A (en) * 1930-05-29 1932-07-26 Forest Alfred V De Thermal method of testing metallic bodies
US2845755A (en) * 1956-11-09 1958-08-05 Gardner Machine Co Selective control devices for disc grinders
US3020745A (en) * 1958-11-13 1962-02-13 Smith Corp A O Method of flaw detection in a metal member
US3206603A (en) * 1962-08-16 1965-09-14 Gen Electric Infrared flaw detector method and apparatus
US3566669A (en) * 1968-09-04 1971-03-02 Harry Parker Method and apparatus for thermally examining fluid passages in a body
US3898440A (en) * 1973-09-08 1975-08-05 Toyoda Machine Works Ltd Size control apparatus for machine tool
US3953943A (en) * 1975-02-27 1976-05-04 Shimadzu Seisakusho Ltd. Apparatus for automatically detecting and eliminating flaws on slabs or billets
US3992826A (en) * 1974-10-15 1976-11-23 Shimadzu Seisakusho Ltd. Apparatus for automatically detecting and eliminating flaws on slabs or billets
US4109508A (en) * 1975-06-26 1978-08-29 Nippon Steel Corporation Method of detecting a surface flaw of metallic material

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1869336A (en) * 1930-05-29 1932-07-26 Forest Alfred V De Thermal method of testing metallic bodies
US2845755A (en) * 1956-11-09 1958-08-05 Gardner Machine Co Selective control devices for disc grinders
US3020745A (en) * 1958-11-13 1962-02-13 Smith Corp A O Method of flaw detection in a metal member
US3206603A (en) * 1962-08-16 1965-09-14 Gen Electric Infrared flaw detector method and apparatus
US3566669A (en) * 1968-09-04 1971-03-02 Harry Parker Method and apparatus for thermally examining fluid passages in a body
US3898440A (en) * 1973-09-08 1975-08-05 Toyoda Machine Works Ltd Size control apparatus for machine tool
US3992826A (en) * 1974-10-15 1976-11-23 Shimadzu Seisakusho Ltd. Apparatus for automatically detecting and eliminating flaws on slabs or billets
US3953943A (en) * 1975-02-27 1976-05-04 Shimadzu Seisakusho Ltd. Apparatus for automatically detecting and eliminating flaws on slabs or billets
US4109508A (en) * 1975-06-26 1978-08-29 Nippon Steel Corporation Method of detecting a surface flaw of metallic material

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* Cited by examiner, † Cited by third party
Title
"Thermal and Infrared Nondestructive Green Testing of Composites and Ceramics" in Materials et al.
Thermal and Infrared Nondestructive Green Testing of Composites and Ceramics in Materials et al. *

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4826326A (en) 1986-09-17 1989-05-02 United Kingdom Atomic Energy Authority Crack sizing
EP0378006A1 (en) * 1989-01-10 1990-07-18 Elkem Technology A/S Method of flaw detection in billets
US5069005A (en) * 1989-01-10 1991-12-03 Elkem Technology A/S Method of flaw detection in billets
US5111048A (en) * 1990-09-27 1992-05-05 General Electric Company Apparatus and method for detecting fatigue cracks using infrared thermography
US5562345A (en) * 1992-05-05 1996-10-08 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method and apparatus for thermographically and quantitatively analyzing a structure for disbonds and/or inclusions
US5240329A (en) * 1992-08-14 1993-08-31 Ford Motor Company Non-destructive method for detecting defects in a workpiece
US20040089812A1 (en) * 2002-08-28 2004-05-13 Wayne State University System and method for multiple mode flexible excitation and acoustic chaos in sonic infrared imaging
US20050167596A1 (en) * 2002-08-28 2005-08-04 Siemens Westinghouse Power Corporation System and method for multiple mode flexible excitation in sonic infrared imaging
US6998616B2 (en) * 2002-08-28 2006-02-14 Wayne State University System and method for acoustic chaos and sonic infrared imaging
US7057176B2 (en) * 2002-08-28 2006-06-06 Siemens Power Generation, Inc. System and method for multiple mode flexible excitation in sonic infrared imaging
US20040262521A1 (en) * 2003-06-30 2004-12-30 Devitt John William Methods for determining the depth of defects
US6874932B2 (en) 2003-06-30 2005-04-05 General Electric Company Methods for determining the depth of defects
US20060067378A1 (en) * 2004-09-29 2006-03-30 Rege Siddharth S Apparatus and method for thermal detection
US7828478B2 (en) * 2004-09-29 2010-11-09 Delphi Technologies, Inc. Apparatus and method for thermal detection

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