Title of Invention

A DEVICE FOR NON DESTRUCTIVE DETERMINATION OF MECHANICAL PROPERTIES OF STEEL SHEETS

Abstract

A device for non-destructive determination of mechanical properties of steel sheets in one direction of a steel sheet specimen, said device comprising: a clamping unit for clamping the steel sheet specimen mechanical property of which is to be determined; a sensing system for generating magnetic field in the specimen and for sensing an induced modulated output signal; a data acquisition and digital signal processing unit for harmonic analysis and computation of characteristic parameters from the induced modulated output signal; and a processor for computation of neural network for correlating the characteristic parameters of harmonics with the mechanical properties of the specimen, characterized in that the processor is utilized for computation of neural network for correlating the characteristic parameters of harmonies with the mechanical properties of the specimen.

Full Text

FIELD OF APPLICATION The present invention relates to a device for non-destructive determination of mechanical properties of steel sheets in one direction of steel sheet specimen. BACKGROUND OF THE INVENTION The mechanical properties of steel are essential to be determined to improve and maintain quality of steel. A device for determining the mechanical properties finds a wide application in the steel industry. The destructive testing of steel specimen is the standard practice for determination of mechanical properties. This process is time consuming and costly. This method of determination of mechanical properties has limitations and problems like, the sample used is destroyed or altered mechanically in the test and highly trained workmanship is required to perform testing. SUMMARY OF THE INVENTION The main object of the present invention is to develop a device to determine mechanical properties non-destructively, which is more accurate and convenient to use. In modern steel making, the mechanical properties can be controlled through physical treatments during manufacturing of steel. Therefore, the measurement of mechanical properties of steel instantaneously throughout the rolling length can be useful not only to ensure the quality of product but also to regulate the process. The device of the present invention for the measurement of mechanical properties non-destructively is based on determining magneto-mechanical analogy of steel sheet specimen. There exists a correlation between magnetic moments of elementary atomic magnets of ferromagnetic material and its mechanical properties. To determine mechanical properties (yield strength, ultimate tensile strength and percentage elongation), in the present invention the steel sheet specimen is introduced between a pair of coils for magneto-inductive coupling. The primary coil having an air core is excited with a sinusoidal voltage source at fixed frequency to generate magnetic field strength in the specimen. The hysteresis curve of the ferro-magnetic material modulates the excitation voltage. This can be reflected as induced voltage in a receiving coil. The harmonic analysis of induced voltage in receiving coil is done to extract features of the particular specimen. The characteristic parameters of the harmonic analysis are correlated with the mechanical values determined by destructive tests. A neural network algorithm is applied to determine this correlation. Thus the present invention relates to a device for non-destructive determination of mechanical properties of steel sheets in one direction of a steel sheet specimen, said device comprising: a clamping unit for clamping the steel sheet specimen mechanical property of which is to be determined; a sensing system for generating magnetic field in the specimen and for sensing an induced modulated output signal; a data acquisition and digital signal processing unit for harmonic analysis and computation of characteristic parameters from the induced modulated output signal; and a processor for computation of neural network for correlating the characteristic parameters of harmonics with the mechanical properties of the specimen. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The invention will be further described below with reference to the accompanying drawing in which: FIG 1 shows a block diagram of the device with all its components. FIG 2 shows the device of the present invention. FIG 3 is a schematic diagram of sensor system. FIG 4 explains the neural network used for correlation. DETAILED DESCRIPTION OF INVFNTION The basic working principle of the device is based on magneto-mechanical analogy. This analogy defines the correlation between the mechanical properties, like yield strength, ultimate tensile strength, percentage elongation and hardness of ferro-magnetic material and magnetic moments of the basic atomic magnets of ferro-magnetic material which are characterized by the shape of the hysteresis curve. The invention can be fully explained with the help of a block diagram of the device as shown in Figure 1. The device of the present invention is provided with a sensor system 3. This sensor system 3 (shown in Figure 2) comprises a primary coil 5 having an air core and excited with a sinusoidal voltage source at fixed frequency to generate magnetic field strength in a specimen 4 to be tested. The specimen 4 is placed with its plane perpendicular to the axis of the sensor system 3 (Figure 3). The hysterisis curve of the ferro magnetic material of the specimen 4 modulates the excitation voltage which is reflected as an induced voltage in a secondary or a receiving coil 6. A data acquisition and digital signal processing unit 8 is provided for carrying out harmonic analysis of the induced voltage In the receiving coil 6 for extracting the features of the test specimen 4. A neural network processor 9 is provided for correlating the parameters of the harmonic analysis from the data acquisition and digital signal processing unit 8 with the mechanical values determined by destructive tests. The mechanical properties of the test specimen 4 can be displayed in a graphic user interface 10 coupled to the processor 9. As illustrated in Figure 2, the device of the present invention can be made as a portable handheld unit. It comprises a clamping unit 1 to clamp steel sheet specimen 4 whose mechanical properties are to be determined. Clamping jaws 2 hold the sensor system 3. The axis of the sensing system 3 is perpendicular to the plane of the sheet specimen 4. The springing action of the clamping jaws 2 holds the specimen 4 in such a way that there is no leakage of flux through the gap. The two coils 5, 6 of the sensor system 3 are held by the clamping jaws 2 of the device. These two coils are placed opposite to each other and perpendicular to the plane of the specimen 4. The schematic diagram is shown in Fig 3. The sinusoidal voltage signal received in the receiving coil 6 is modulated by the hysteresis curve of the specimen, which acts as a magnetic coupling between the two coils. The receiving coil 6 comprises a coil with more number of turns as compared to the primary coil 5 wound on an E shaped soft iron core 7. The core 7 is used to increase the sensitivity of the receiving coil 6. A sensor is provided for measuring the thickness of the specimen 4. Fast Fourier transform can be used for harmonic analysis of the received voltage induced in the receiving coil. The data acquisition and digital signal processing unit 8 used for the analysis can be a DSP processor for computing the characteristic parameters of harmonics induced by the specimen 4. The results obtained from the harmonic analysis are to be correlated with the mechanical properties of the specimen obtained from the destructive tests. Since there are no simple equations for solving the correlation - the only information available is a set of characteristic parameters of harmonic analysis of the specimen. The correlation is obtained by designing and training a neural network. The neural network can be trained' with the harmonic information of a small group of specimens, the mechanical properties of which are known by destructive method. The thickness of the sheet specimen 4 also becomes an input along with the harmonic information, to determine the accurate correlation. Once the neural network converges with minimum error, it is ready to analyze properties of unknown specimen. Fig 4 explains the neural network used for correlation. The device of the present invention can measure the mechanical properties in one direction. It can be rotated to measure the mechanical properties in any other direction. The processor 9 used for computation of neural network can be a computer. This processor can also have a graphic user interface designed to make the whole process (i.e. placing commands to viewing the mechanical properties) user friendly by displaying the mechanical properties in a displaying unit 10. The device for non-destructive determination of mechanical properties of steel sheet reduces the number of destructive tests which are time consuming and costly. The mechanical properties can be instantaneously determined. It helps in making material choice according to the quality criteria and preserving the product quality. The device of the present invention can be put on line for measuring properties throughout the rolling length. The on-line usage of the device can aid in regulating the process. WE CLAIM: 1. A device for non-destructive determination of mechanical properties of steel sheets in one direction of a steel sheet specimen, said device comprising: a clamping unit for clamping the steel sheet specimen mechanical property of which is to be determined; a sensing system for generating magnetic field in the specimen and for sensing an induced modulated output signal; a data acquisition and digital signal processing unit for harmonic analysis and computation of characteristic parameters from the induced modulated output signal; and a processor for computation of neural network for correlating the characteristic parameters of harmonics with the mechanical properties of the specimen, characterized in that the processor is utilized for computation of neural network for correlating the characteristic parameters of harmonies with the mechanical properties of the specimen. 2. The device as claimed in claim 1, wherein said device is a portable hand held unit. 3. The device as claimed in claim 1, wherein said sensing system comprises a primary coil and a receiving coil arranged opposite to each other for respectively generating the magnetic field and for sensing the induced modulated output signal. 4. The device as claimed in claim 1, wherein said clamping unit is provided with clamping jaws having said sensing system and for holding said specimen with the central axis of the sensing system perpendicular to the plane of the specimen. 5. The device as claimed in claim 4, wherein said primary coil is an air core coil and is excited with constant voltage source at constant frequency, and said receiving coil is mounted on an E shaped soft iron core. 6. The device as claimed in the preceding claims, wherein said receiving coil has more number of turns as compared to that of said primary coil. 7. The device as claimed in claim 3 wherein said sensing system is provided with a thickness measurement sensor for measuring the thickness of the sheet specimen. 8. The device as claimed in claim 9, wherein said digital signal processing unit is a DSP processor for computation of characteristic parameters of harmonics induced by the sheet specimen as the output of said receiving coil. 9. The device as claimed in claim 1, wherein said processor is provided with a graphic user interface for displaying the mechanical properties. 10. A device for non-destructive determination of mechanical properties of steel sheets in one direction of a steel sheet specimen substantially as herein described and illustrated in the accompanying drawings. A device for non-destructive determination of mechanical properties of steel sheets in one direction of a steel sheet specimen, said device comprising: a clamping unit for clamping the steel sheet specimen mechanical property of which is to be determined; a sensing system for generating magnetic field in the specimen and for sensing an induced modulated output signal; a data acquisition and digital signal processing unit for harmonic analysis and computation of characteristic parameters from the induced modulated output signal; and a processor for computation of neural network for correlating the characteristic parameters of harmonics with the mechanical properties of the specimen, characterized in that the processor is utilized for computation of neural network for correlating the characteristic parameters of harmonies with the mechanical properties of the specimen.

Documents:

811-KOL-2004-FORM 15.pdf

811-kol-2004-granted-abstract.pdf

811-kol-2004-granted-claims.pdf

811-kol-2004-granted-correspondence.pdf

811-kol-2004-granted-description (complete).pdf

811-kol-2004-granted-drawings.pdf

811-kol-2004-granted-examination report.pdf

811-kol-2004-granted-form 1.pdf

811-kol-2004-granted-form 13.pdf

811-kol-2004-granted-form 18.pdf

811-kol-2004-granted-form 2.pdf

811-kol-2004-granted-form 3.pdf

811-kol-2004-granted-form 5.pdf

811-kol-2004-granted-gpa.pdf

811-kol-2004-granted-reply to examination report.pdf

811-kol-2004-granted-specification.pdf