Abstract: A method of non-contact measurement of a thickness (d) of an object of an electrically conductive material by means of a Pulsed Eddy Current, PEC, system including a transmitter coil and a receiver coil. The method includes, after having turned off a current in the transmitter coil, at the receiver coil, measuring a voltage induced by the decaying magnetic field at a first time point, a second time point, and a third time point. The method also includes calculating a total magnetic flux which is generated by the eddy currents in the object at the first time point and picked up by the receiver coil, by comparing the measured flux at the first time point with a predetermined total flux picked up by the receiver coil when no object is present.

Abstract: The invention relates to a method of determining a crack at an edge of a metallic material, the edge having a curvature with a radius. The method including: feeding and controlling a current to a transmitter coil for generating a magnetic field in the metallic material, detecting the magnetic field by means of a receiver coil, which detected magnetic field thereby generates a signal) in the receiver coil, determining first, second and third signal values of the signal at a first time, a second time and a third time, respectively, determining a possible presence of a crack and its crack depth based on the first, second and third signal values by means of determining a characteristic relation between the signal values.

Abstract: A method of removing a crack in a metallic material during a metal making process. The method including: determining the presence of a crack and its crack depth during the metal making process by a crack detecting unit utilizing inductive measurement, sending a crack detection signal and crack depth to a crack removal unit arranged on known distance from the crack detecting unit, the crack removal unit including an ejector configured to eject a carving means, and to vary the intensity of the ejected carving means, removing the detected crack by activating the ejector based on the crack detection signal with an intensity of the ejected carving means based at least on the crack depth.

Abstract: A method of non-contact measurement of a thickness (d) of an object of an electrically conductive material by means of a Pulsed Eddy Current, PEC, system including a transmitter coil and a receiver coil. The method includes, after having turned off a current in the transmitter coil, at the receiver coil, measuring a voltage induced by the decaying magnetic field at a first time point, a second time point, and a third time point. The method also includes calculating a total magnetic flux which is generated by the eddy currents in the object at the first time point and picked up by the receiver coil, by comparing the measured flux at the first time point with a predetermined total flux picked up by the receiver coil when no object is present.

Abstract: An arrangement for a metal making process for detecting cracks along a strip of a metallic material moving in relation to the arrangement. The arrangement includes a coil arrangement fixedly arranged during crack inspection, having: a first winding portion extending in a first direction for inducing a first current in the first direction; a second winding portion extending in a second direction for inducing a second current in the second direction, the first direction and the second direction intersecting each other; a first receiver coil arranged to detect a magnetic field generated by the first current; and a second receiver coil arranged to detect a magnetic field generated by the second current, the magnetic field generated by the first current and the magnetic field generated by the second current providing a measure of whether a crack is present in the portion of the strip.

Abstract: A method of determining a crack depth of a crack in a metallic material including the steps: feeding a current with a first magnitude to a transmitter coil for generating a magnetic field in the metallic material; controlling the current such that it obtains a second magnitude when the magnetic field is estimated to have penetrated deeper than a deepest crack depth desired to be measured in the metallic material; detecting the magnetic field by means of a receiver coil; determining a first characteristic value of the signal in a first time range; determining a second characteristic value of the signal in a second time range after the first time range; and determining a possible presence of a crack and its crack depth based on the first characteristic value and the second characteristic value.

Abstract: An arrangement for a metal making process for detecting cracks along a strip of a metallic material moving in relation to the arrangement. The arrangement includes a coil arrangement fixedly arranged during crack inspection, having: a first winding portion extending in a first direction for inducing a first current in the first direction; a second winding portion extending in a second direction for inducing a second current in the second direction, the first direction and the second direction intersecting each other; a first receiver coil arranged to detect a magnetic field generated by the first current; and a second receiver coil arranged to detect a magnetic field generated by the second current, the magnetic field generated by the first current and the magnetic field generated by the second current providing a measure of whether a crack is present in the portion of the strip.

Abstract: A method of determining a crack depth of a crack in a metallic material including the steps: feeding a current with a first magnitude to a transmitter coil for generating a magnetic field in the metallic material; controlling the current such that it obtains a second magnitude when the magnetic field is estimated to have penetrated deeper than a deepest crack depth desired to be measured in the metallic material; detecting the magnetic field by means of a receiver coil; determining a first characteristic value of the signal in a first time range; determining a second characteristic value of the signal in a second time range after the first time range; and determining a possible presence of a crack and its crack depth based on the first characteristic value and the second characteristic value.

Abstract: A method for supervising a process for producing a metal alloy object with a known chemical composition. A resistivity of the metal alloy object is determined. A content of dissolved alloying elements in the metal alloy object is estimated based on the determined resistivity and the chemical composition of the metal alloy object. A content of precipitated alloying elements in the metal alloy object is estimated based on the determined resistivity and the chemical composition of the metal alloy object. The production process is supervised based on a ratio between the estimated content of dissolved alloying elements and the estimated content of precipitated alloying elements.

Abstract: An apparatus for estimating or supervising one or more internal mechanical properties of a metal alloy object with a known chemical composition based on the resistivity of the metal alloy object. The apparatus includes a device for measuring the resistivity of the metal alloy object, and a computation unit adapted to calculate the content of dissolved alloying elements in the metal alloy object based on the measured resistivity and the known chemical composition of the metal alloy, and based thereon to calculate at least one internal mechanical property of the metal alloy object.

Abstract: A method and an apparatus for measuring the thickness of a metal layer. The metal layer has a resistivity (?1) that differs from the resistivity (?2) of the metal object. The apparatus includes a first device arranged to generate a magnetic field in close vicinity of the metal layer, and to generate a variation of the magnetic field so that a current is induced in the surface of the metal layer, a second device arranged to measure the changes of the magnetic field outside the metal layer due to the induced current during a time period that is longer than the time it takes for the current to propagate through the metal layer, and a computing unit to determine the thickness of the layer based on a mathematical relation between the thickness of the layer and the measured values of the changes of the magnetic field.

Abstract: A method and an apparatus for measuring the thickness of a metal layer. The metal layer has a resistivity (?1) that differs from the resistivity (?2) of the metal object. The apparatus includes a first device arranged to generate a magnetic field in close vicinity of the metal layer, and to generate a variation of the magnetic field so that a current is induced in the surface of the metal layer, a second device arranged to measure the changes of the magnetic field outside the metal layer due to the induced current during a time period that is longer than the time it takes for the current to propagate through the metal layer, and a computing unit to determine the thickness of the layer based on a mathematical relation between the thickness of the layer and the measured values of the changes of the magnetic field.

Abstract: A method for non-contact determination of sought properties of an object to be measured by using electromagnetic induction. An electromagnetic field is generated in a transmitter coil placed on one side of the object to be measured. The magnetic field penetrates through the object to be measured and is detected by a receiver coil placed on the other side of the object to be measured. A control coil is placed near the transmitter coil generating a change in the magnetic field of the transmitter coil. A field change in the detecting is detected in the control coil. The field is detected in the receiver coil. The difference in time is determined for the detection of the field change in the control coil and in the receiver coil, respectively. The time of penetration through the object to be measured is determined, and the thickness or electrical conductivity of the object to be measured is determined therefrom.

Abstract: A method for non-contact measurement of a dimension and/or an electrical property in an electrically conducting object to be measured by using electromagnetic induction. An electromagnetic field is brought to penetrate through the object to be measured. A transmitter coil is place on one side of the object to be measured. A receiver coil is placed on the other side of the object to be measured. A magnetic field is generated in the transmitter coil. A sudden change is generated in the magnetic field generated in the transmitter coil from one level to another. The voltage induced in the receiver coil is detected. The period of time that elapses from the time of the change of the magnetic field in the transmitter coil up to the time when a voltage starts to be induced in the receiver coil is determined. The magnitude of the induced voltage is determined. The thickness and/or electrical conductivity of the object to be measured is calculated.

Abstract: An apparatus for estimating or supervising one or more internal mechanical properties of a metal alloy object with a known chemical composition based on the resistivity of the metal alloy object. The apparatus includes a device for measuring the resistivity of the metal alloy object, and a computation unit adapted to calculate the content of dissolved alloying elements in the metal alloy object based on the measured resistivity and the known chemical composition of the metal alloy, and based thereon to calculate at least one internal mechanical property of the metal alloy object.

Abstract: A method for non-contact determination of sought properties of an object to be measured by using electromagnetic induction. An electromagnetic field is generated in a transmitter coil placed on one side of the object to be measured. The magnetic field penetrates through the object to be measured and is detected by a receiver coil placed on the other side of the object to be measured. A control coil is placed near the transmitter coil generating a change in the magnetic field of the transmitter coil. A field change in the detecting is detected in the control coil. The field is detected in the receiver coil. The difference in time is determined for the detection of the field change in the control coil and in the receiver coil, respectively. The time of penetration through the object to be measured is determined, and the thickness or electrical conductivity of the object to be measured is determined therefrom.

Abstract: A method for non-contact measurement of a dimension and/or an electrical property in an electrically conducting object to be measured by using electromagnetic induction. An electromagnetic field is brought to penetrate through the object to be measured. A transmitter coil is place on one side of the object to be measured. A receiver coil is placed on the other side of the object to be measured. A magnetic field is generated in the transmitter coil. A sudden change is generated in the magnetic field generated in the transmitter coil from one level to another. The voltage induced in the receiver coil is detected. The period of time that elapses from the time of the change of the magnetic field in the transmitter coil up to the time when a voltage starts to be induced in the receiver coil is determined. The magnitude of the induced voltage is determined. The thickness and/or electrical conductivity of the object to be measured is calculated.

Abstract: A method, system and inductive device for accurately determining inclination of a shaft arranged with a gear wheel including a plurality of gear teeth. The inductive measuring device includes a transmitter coil and at least two receiving coils arranged adjacent relative an axis of symmetry of the transmitter coil. Voltages in the receiving coils are measured, summed and integrated. A zero value for the integral is used to determine the position of the center line of the gear tooth. The invention may be used for diagnostic and/or control purposes of an internal combustion engine.

Abstract: A method, system and inductive device for accurately determining inclination of a shaft arranged with a gear wheel including a plurality of gear teeth. The inductive measuring device includes a transmitter coil (3) and at least two receiving coils (7, 8) arranged adjacent relative an axis of symmetry (9) of the transmitter coil. Voltages in the receiving coils are measured, summed and integrated. A zero value for the integral is used to determine the position of the centre line of the gear tooth 5. The invention may be used for diagnostic and/or control purposes of an internal combustion engine.

Abstract: A method for non-contact measurement of dimensions such as thickness or diameter and electrical characteristics of an electrically conductive object (6) based on electromagnetic induction and a time-varying magnetic field. A substantially constant current is supplied to at least one transmitter coil (3) such that an electromagnetic field penetrates the object (6). Current to the transmitter coil (3) is cut off and a voltage induced in at least one receiving coil (8) by at least one decaying magnetic field. The voltage in receiving coil (8) is measured from a first time following decay of a magnetic field in the air (T3) until a time when the field has decayed to zero (T4, T5, T6) and the signal is integrated. A value for a physical dimension of the object (6) is calculated from this integral. The method is accurate, undisturbed by surface contamination or object movement, and applicable to different geometric forms including plate, bar or tube.