CA1260064A - System for online-detecting transformation value and/or flatness of steel or magnetic material - Google Patents
System for online-detecting transformation value and/or flatness of steel or magnetic materialInfo
- Publication number
- CA1260064A CA1260064A CA000465120A CA465120A CA1260064A CA 1260064 A CA1260064 A CA 1260064A CA 000465120 A CA000465120 A CA 000465120A CA 465120 A CA465120 A CA 465120A CA 1260064 A CA1260064 A CA 1260064A
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- Prior art keywords
- exciting coil
- steel
- flatness
- detecting
- online
- Prior art date
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- 239000010959 steel Substances 0.000 title claims abstract description 74
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- 239000000696 magnetic material Substances 0.000 title claims abstract description 16
- 230000005291 magnetic effect Effects 0.000 claims abstract description 50
- 238000001514 detection method Methods 0.000 claims abstract description 40
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- 238000000844 transformation Methods 0.000 description 3
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- 230000005298 paramagnetic effect Effects 0.000 description 2
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- 101000837192 Drosophila melanogaster Teneurin-m Proteins 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
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- 238000012423 maintenance Methods 0.000 description 1
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Landscapes
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In a system for online-detecting a transformation value and/or a flatness of a steel or a magnetic material, an exciting coil disposed at either one side of the plate-shaped steel or magnetic material as being the material to be measured and capable of generating alternating magnetic fluxes by alternating current excitations: two or more detecting coils arranged on the same side as the exciting coil and at positions different in distance from the exciting coil, and mutually induced with the exciting coil; and an arithmetic unit for obtaining the transformation value and the flatness of the steel or the magnetic material or either one of those from a difference between detection signals generated from a difference in values of interlock magnetic fluxes in the respective detecting coils are provided, so that the transformation value and the flatness of the steel or the flatness of the magnetic material can be detected with high accuracy.
In a system for online-detecting a transformation value and/or a flatness of a steel or a magnetic material, an exciting coil disposed at either one side of the plate-shaped steel or magnetic material as being the material to be measured and capable of generating alternating magnetic fluxes by alternating current excitations: two or more detecting coils arranged on the same side as the exciting coil and at positions different in distance from the exciting coil, and mutually induced with the exciting coil; and an arithmetic unit for obtaining the transformation value and the flatness of the steel or the magnetic material or either one of those from a difference between detection signals generated from a difference in values of interlock magnetic fluxes in the respective detecting coils are provided, so that the transformation value and the flatness of the steel or the flatness of the magnetic material can be detected with high accuracy.
Description
~X~06D~
SYSTEM FOR ONLINE-DETECTING TRANSFORMATION VALUE AND/O~ FLATNESS
OF STEEL OR MAGNETIC MATERIAI, BACKGROUND_OF_THE__NVENTION
1. Field of the Invention This invention relates to a system for online-detecting a transformation value and the flatness or either one of those of a steel or a magnetic material.
SYSTEM FOR ONLINE-DETECTING TRANSFORMATION VALUE AND/O~ FLATNESS
OF STEEL OR MAGNETIC MATERIAI, BACKGROUND_OF_THE__NVENTION
1. Field of the Invention This invention relates to a system for online-detecting a transformation value and the flatness or either one of those of a steel or a magnetic material.
2. Description of the Prior Art As the methods of strengthening a steel, there are variuous ones including the work hardening, precipitation hardening, solution hardening, refining of grain size, transformation structure strengthening and the like.
Backed by the tendency of manufacturing cost reduction of steel products, recently, there has been activated the utilization of the transformation structure strengthening technique through the controlled cooling after the hot rolling as a measure of manufacturing a higher strength steel in a hot rolled state, using a steel blank having low alloy contents.
Now when the transformation structure strengthening technique is utilized, needless to say, it is necessary to have accurate knowledge about the transformation behavior of steel.
As for the transformation behavior, ones which have been studied in the experimental manners in a laboratory, in general.
However, in many cases, ones which are manufactured by an actual system are different from the results of experiments in the laboratory to a considerable extent. Although the actural .~.
conditions have not been fully grasped yet, one of the reasons for the difference of the transformation behavior in the actual system from the results of experiments in the laboratory is said to be that the transformation behavior is complicatedl~ varied depending upon the history of thermal strains and the like in the preceding process or an upstream process. In consequence, for example, (A) as a measure of grasping the variations in a local transformation behavior due to a difference in the histories of rolling temperature to improve the homogeneity in the material on the longitudinal and widthwise directions, which is a major factor governing the matexial quality of a hot-tolled steel, (B) as a measure of grasping a ratio between gamma phase and alpha phase at the time of appl~ing the reduction to manufacture a steel having a high strength and being excellent lS in toughness, e. g. a steel plate for a high tension line pipe, or (~) as a measure of grasping a ratio of gamma phase and alpha phase at the time of starting the quenching in the manufacturing technique of a mix~d structure steel to manufacture a thin steel plate having a high strength and being excelle~t in workability, if online information about the transformation behavior of steel would be precisely detected, then a great profit would be expected in the field of manufacturing various steels, where a hot rolling line and a heat treating line are used.
Heretofore, there has been proposed the following method as 2S a method of online-detecting the above-described transformation behavior of steel. One of those is a method wherein the rise in temperature due to the latent heat at the time of the phase ~26(~06~L
transformation is detected by a thermometer installed on a manufacturing line to grasp a transformation behavior as described in Japanese patent publication No. 24017/81 for example. However, this method is disadvantageous in that obtainable information is gi~en in excessively broad outline, the response is slow and the thermometer is used as a sensor, with the result that the measurement during water cooling cannot be conducted.
Forthermore, as described in Japanese patent laid-open Nos.
114518/74, 136442/76 and Japanese patent puhlication No.
25309/78, there have been proposed methods, in which X-rays are irradiated onto the surface of a steel, and the transformation value is measured from a difraction strength. However, this method is disadvantageous in that it is necessary to take safety protective measure from the X-ray injuries since strong X-rays are irradiated, and consequently, the detection system itself becomes large-sized, resulting in increased installation cost, a limited installed number, occurrence of maintenance problems and the like. Additionally, since the obtainable information remains within the surface layer portion of about 50 micro meters or less o~ the material to be measured, it is difficult that the obtainable information can be used as a macroscopic information.
In contrast thereto, there have been proposed methods of detecting the transformation behavior by use of a magnetic detector, utilizing the fact that the transformation from gamma phase to alpha phase of steel is accompanied by a physical ~26~)~J16~L
phenomenon of a change from the paramagnetism (gamma phase) to the ferromagnetism ~alpha phase). For example, Japanese patent laid-open Nos. 104754/75 and 82443/81 correspond to these proposals. These methods are problematical in that the measurable temperature range is limited to a temperature region of the Curie point or less of the steel to be measured.
However, in most cases, the Curie points of ordinary commercial steels are as high as about 750C. In contrast thereto, the range of transformation o the steel during cooling process is transfered in non-e~uilibrium condition to the low temperature side, whereby the most part of transformation proceeds within a temparature range of the C'urie point or less, so that these methods are advantageous in that the above-mentioned problems do not impose practical obstacles except some types of steels, are used easier in practice and the response is good as compared with other methods not utili~ing the aforesaid magnetic means, moreover, the measurements are practicable during wat~r cooling and so on, thereby proving to be practical and effective methods. Although the magnetic detecting systems proposed by Japanese patent laid-open Nos. 104754/75 and 82448/81 have the following problems not solved yet, it cannot be said that those detecting systems are satis~actorily practicable.
Firstly, description will be given of Japanese patent laid-open No. 104754/75. This proposal relates to a hot rolling method utilizing a magnetic detecting system, not relating to the magnetic detecting system itself, thus the details about the fuctions and construction of the detecting system in the ~2~0~
practical use are unclear. However, according to the description in the specification of the proporal, an excited pickup coil is placed close to the steel to be measured, and the presence of transformation is qualitatively detected from a change in impedance of the pickup coil itself generated due to the transformation of the steel to be measured from gamma phase to alpha phase. However, in order to apply the proposal to the manufacturing field of steel as aforesaid, it is necessary to have a function capable of quantitatively detecting the progress of transformation as the function of the magnetic detecting device. With the detecting device capable of only qualitatively detecting the presence of the transformation as described in the proposal, it should be said that the value of application is low.
Description will now be given of Japanese patent laid-open No. 82443/81. Fig.l is a block diagram showing the arrangement of the magnetic detecting system in this proposal. This magnetic detecting system is of such an arrangement that an exciting coil 3 wound around a magnetic pole 2 composed by a U-shaped iron core and magnetic flux detector 6 are spaced a predetermined distance Ls from each other, interposing a steel 1 as being a material to be measured therebetween, and the exciting coil 3 is excited by an exciting device 4, whereby, out of magnetic fluxes 5 generated by the excitation, the intensity of a magnetic flux 5O which penetrates through the steel 1 and is leaked to reach the flux detector 6 is detected. The transformation value is detected from a change in intensity of _ 5 _ ~0C~6~L
the flux 5O generated in accordance with a transformation value in the steel 1. In the drawing, designated at 7 i5 a thermometer, 8 an arithmetic unit, and 9 condition signals of the material, of plate thiclcness and the like. Although this method has a function capable of quantitatively measuring the transformation value in principles as compared with the aforesaid Japanese patent laid-open No. 104754/75, it has the following disadvantages in the application to an actual manufacturing line.
Namely, in the above arrangement, the intensity of the magnetic flux 5O (magnetic flux density) is substantially inversely proportional to the distance Ls between the magnetic pole 2 and the magnetic flux detector 6, and hence, in order to detect the transformation value with satisfactory accuracy, it is necessary to make the distance Ls to be at least about 150 mm or less. However, it should be said that it is extremely difficult to move the steel 1 through such a narrow gap without contacting the magnetic flux detector 6 in the application of the proporal to the actual manufacturing line. ~his is because that a hot-rolled steel plate manufactured in a hot strip mill and plate mill for example has a buckling, camber, waving and/or the like in the shape of after hot rolling, should not necessarily be fla~t, particularly this tendency is strong in the forward end, rear end and therearound of the rolled steel and ~5 hence, contact of the detector 6 with the steel 1 is inevitable during conveyance of the steel. In order to avoid such an accident, there is proposed such a method that the aforesaid gap ~l2~064 is temporarily expanded during the passing therethrough by the forward end or rear end portion of the steel for example.
H~wever, the variability in material quality tends to occur in the forward end, rear end portion or therearound, and hence, if it is impossible to detect these portions, then the value of installing the detecting device should be lost by half.
Furthermore, the magnetic detecting system of the proposal is disadvantageous in that, since a vacant space portion in a magnetic circuit through which the magnetic fluxes 5 are passed is varied depending upon the difference in plate thickness t of the steel 1 as being the material to be measured, it is necessary to correct a det:ection output by the plate thickness t, further, the measuring accuracy depends upon the actual plate thickness t, and so on. However, the plate thickness t of the steel 1, which is rolled by an ordinary hot rolling mill is widely varied in such ways as 1.2 - 30 mm in a hot strip mill and 5.0 - 300 mm in a plate mill for e~ample. The correcting operations are complicated, and it is difficult Erom the viewpoint of the characteristics of the conveyance of the steel 1 to substantially obtain the proper detecting accuracy in accordance with the actual plate thickness t.
As described above, it should be said that the magnetic detecting system proposed by Japanese patent laid-open No.
82~43/81 has many problems in the application to the actual manufacturing line.
SUM~RY OF THE INVENTION
The present invention has been developed to obviate the ~ 2t~(~06~
-above-described dlsadvantages of -the prior art and has as its Eirst object the prov:ision oE a magnetic detecting system being multiply functional, wherein a transformation value of a steel, which has not been detectable by the conven-tional method, is precisely detected, and fur-ther, even the fla-tness of lhe steel can be detected with high accuracy at the same time.
A second object of -the present invention is to provide a magnetic detecting system capable of de-tect-ing the flatness of a rnagnetic material with high accu-racy.
According to the presen-t invention, there is provided a system for online-detection of either a -trans-formation value and a flatness of a s-teel or one of said transforma-tion valve and flatness,comprising:
an exciting coil located at a spaced distance from one side of a surface of the steel and capable of generating alternating magnetic fluxes by alternating current excitations;
at least -two detecting coils arranged on a same side and at substantially a same spaced distance from said s-teel as said exciting coil, said detecting coils being arranged at positions different in distance from said exciting coil in a direc-tion parallel to -the sur-face of said steel, and having induced vol-tages due to the magnetic fluxes generated by said exciting coil;
and an ari-thmetic uni-t for calculating and outputt-ing ei-ther the -transformation value and the flatness of said steel or one of said transformation value and flat-ness, said arithmetic unit being independently electri-cally coupled with each of said detecting coils such that values of -the induced voltages in the detectin~ coils are input into said arithmetic unit and at least one of 06a~
- 8a -the -transEorma-tion value and the fla-tness of saicl steel is calculated by the ari-thmetic unit in accordance with a predetermined formula using the values oE the induced voltages.
A specific Eorm of the present invention is of such an arrangement that the two or more detec-ting coils are disposed _ _ _ ~l26~)0~
within a range of 2~0 mm or less from the exciting coil, respectively, and spaced 20 mm or more apart from each other, so that high detectin~ accuracy can be reliably obtained.
Another specific form of the present invention is of such an arrangement that one of the detecting coils is disposed concentrically with the exciting coil, so that a space for installation can be minimized.
A further specific form of the present invention is of such an arrangement that at least one coil out of the exciting coil and the detecting coils is provided therein with a core Eor exclusive use, which does not stride over any one of other coils, so that magnitudes of detection signals can be greatly increased.
A still further specific form of the present invention is of such an arrangement that only the exciting coil is provided therein with a rod-shaped core, so that the exciting magnetic field is increased in its intensity.
A still further specific form of the present invention is of such an arrangement that independent rod-shaped cores are provided in all of the exciting coil and the detecting coils, respectively, so that the magnitudes of the detection signals can be maximised.
A still further specific form of the present invention is of such an arrangement that all of the exciting coil and the detecting coils are co~monly provided with a comb-shaped core striding over all of the coils, so that the installation work can be facilitated.
6~
A s-till Eurther specific Eorm of the present invention is of an arrangement that a Erequency o:E excit-ing current applied to the exciting coil i.s held w:ithin a range of 5~1z - 10 KH~ so that the suitable penetrating depth of magnetic fluxes, the good response speed of the detecting device, -the high S/N ratio (Signal to Noise ratio) between the de-tection signals and the like can be obtained respectively.
According -to -the present invention, there is also provided a system for online-detec-tion of a flatness of a magnetic materia~,comprising:
an exciting coil located at a spaced dis-tance from one side of a surface of the magnetic ma-terial and capable of generating alternating magnetic fluxes by al-ternating current excitations;
at least -two detecting coils arranged on a same side and at substantially a same spaced distance from said magneti.c ma-terial as said exciting coil, said detect-ing coils being arranged at positions different in dis-tance from said exciting coil in a direction parallelto the surface of said magnetic material, and having in-duced vol.tages due to -the magnetic fluxes genera-ted by said exciting coil; and an arithmetic unit for calculating and outputt-ing the flatness of said magnetic material, said arith-metic unit being independently electrically coupled with each of said detecting coils such that values of -the in-duced voltages in the detecting coils are inpu-t in-to said arithmetic unit and the flatness of said magnetic material is calculated by the arithmetic unit in accordance with a predetermined formula using the values of -the induced voltages.
As described above, according to the presen-t inven-tion, two or more de-tec-ting coils are arranged on ~6~6a~
- lOa -the same side as the exciting coil and at positions diE-ferent in distance from the excit:ing coll and the trans-formation value and the Elatness (lift-ofE) of a steel as being the material -to be measured are simultaneously sought by the detec-tiny signals, so that the _ ~6C)1~:36~
following advantages are ohtainable.
~A) The mutual induction by the magnetism is utilized for the detection, so that the detection is accurate, the response is good and the system is excellent as quantitative detecting S means in online.
(B) The components of the detecting system can be concentrically disposed on one side of the material to be measured, so that, even in the manufacturing line where the flatness of the material is not so good, the system is satisfactorily practicab:LeO
(C) Although the cor,lponents are disposed at one side of the material, the transformation value of the steel can be detected with the system not being subjected to the influence of the fluctuations in lift-off.
(D) The online in~ormation on the lift-off, i.e. the flatness of the material can be collectively or singly detected.
(E) While the flatness of the material can be detected by the magnetic detection, the system is not subjected to the influence of the transformation value of the steel.
(F) The system is widely usable in the various cases including ambient conditions of high temperature, under water and the like.
In consequence, not only the online detection of the transformation value of the steel in the various hot rolling processes and heat treatment processes, but also the online detection of the flatness are simultaneously conducted.
Further, the detection should not necessarily be limited to the - 11 ~
steel, only if the material to be measured may give some influence to the mutual induction between the exciting coil and the detecting coils, the flatness of t:he material to be measured can be online-detected irrespective of the presence of the transformation behavior. Thus, the system can be applied to uses of a very wide range.
BRIEF DESCRIPTION OF TH.~ DRAWINGS
. .
The exact nature of this invention, as well as other objects and advantages therof, will be readily apparent from consideration of the following specification relating to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the ~igures thereof and wherein:
Fig. 1 is a partially sectional block diagram showing the conventional example of the magnetically measuring type transformation value detecting system;
Fig. 2 is a block diagram corresponding to Fig. 1, showing a first embodiment of the present invention:
Fig. 3 is a chart showing the interrelation of the increase or decrease of the lift-off and transformation value with the detection signals at the detecting coils, in explanation of the principles of the present invention;
Fig. 4 is a block diagram corresponding to Fig. 2, showing a second embodiment of the present invention;
Fig. 5 is a chart showing the relationship of the intervals between the detecting coils with the measuring errors in lift-off;
Figs. 6 to 8 are block diagrams corresponding to Fig. 2, ~X6(~06~
showing a third to a fifth embodiments of the present invention;
and Fig. 9 is a chart showing the relationship of the respective embodiments with the second embodiment about the magnitudes of the detection signals when the core is provided in the exciting coil or the detecting coils.
DETAILED DESCRIPTION OF THE INVENTION
Detailed description will hereunder be given of the present invention with reference to the accompanying drawings.
Fig. 2 shows the first embodiment of the present invention.
In the drawing, designated at 1 is a steel being the material to be measured, 12 an alternating current (AC) exciting device, 13 an exciting coil, and 151 and 152 detecting coils disposed at positions different in distance (Dl and D2) from the exciting coil 13. Denoted at 141 is a magnetic flux generated at the exciting coil 13 and interlinked with the detecting coil 151 through the steel 1 and 142 a magnetic flux interlinked with the detecting coil 152.
Now, such a state stands here that the steel 1 does not begin to transform, i.e. the paramagnetic condition, in which the steel 1 is in the single gamma phase. In this state thereinafter referred to as "the initial state"), the magnetic fluxes 141 and 142 interlinked with the detecting coils 151 and 152 have predetermined intensities corresponding to the distances Dl and D2 from the exciting coil 13 and induced voltages propostional to the predetermined intensities, respectively.
~L2~6~
When the steel 1 begins to transform from gamma phase to alpha phase and a paramagnetic alpha phase precipitates, the alpha phase is magnetized, fluctuations are caused to the intensity of magnetic field of the steel 1, and the intensities of the magnetic fluxes 141 and 142 are shifted f.rom the initial st~te ! whereby the resu:l.ts are detected as the changes in the induced voltages in the detecting coils 151 and 152.
Furthermore, when a ~istance L between the steel 1 and the exciting coil 13 (hereinafter referred to as a "lift-off", and measuring the lift-off means measuring the flatness) is varied, the induced voltages at the detecting coils 151 and 152 are changed, respectively Detection signals 161 and 162 thus obtained at the detecting coils 151 and 152 are delivered to an arithmetic unit 17, where the magnitudes of the signals measured at the detecting coils 151 and 152 are compared, and a transformation value and a lift-off L are separately calculated in accordance with the relationship to be described hereunder, which is previously stored in the arithmetic unit 17.
Description will now be given of a technique of obtaining 2~ the transformation value in the steel 1 and the lift-off L from the magnitudes of the detection signals 161 and 162 of the detecting coils 151 and 152.
Fig. 3 shows the relationship between the detection signals ~vaxied values in the induced voltages from the initial state ) of the detecting coils 151 and 152 when the gamma to alpha transformation value of the steel 1 and the lift-off L are varied in a detecting system basically following the arrangement ~LZ~) [)6~
shown in Fig. 2, wherein the diskance Dl from the exciting coil 13 to the detecting coil 151 is made to be 50 mm and the distance D2 from the exciting coil 13 to the detecting coil 152 is made to be 100 mm. In Fig. 3, those indicated by broken S lines are relationships in the cases where the transformation values are at constant ~alues and only the lift-off L is varied, and those indicated by solid lines are relationships in the cases where the lift-of L are at constant values and only the transformation value is varied. As apparent from Fig. 3, the relationship in magnitude between the detection signals 161 and 162 of the detecting coils 151 and 152 assumes a curved line as shown in 0 - a - b - c - d - e - f when the lift-off L is varied, whereas the aforesaid relationship assumes a generally stxaight line as shown in 0 - j - i - h - g - f when the transformation value is varied. Namely, it is found that vector quantities determined by the detection signals 161 and 162 of the two detecting coils 151 and 152 have intrinsic relationships with the transformation value and the lift-off I" respectively.
In consequence, the precise relationships shown in Fig. 3 are previously obtained, stored in the arithmetic unit 17 shown in Fig. 2, and compared with the detection signals 161 and 162 detected by the detecting coils 151 and 152 for calculaticn, so that the transformation value and the lift-off L can be simultaneously obtained.
In the foregoing, description has been given of the case where two detecting coils are used. It is natural that the same thing should be true of the cases where the number of the ~ 26C~
detecting coils are more than two. Needless to say, the number of the detecting coils i5 increased, whereby measurements by use of three or four detecting coils are conducted, so that a further precise measurement can be accomplished. As apparent from the above description, according to the present invention with the above-described arrangexnent, information on "only the transformation value", "the transformation value and the flatness" or "only the flatness" can be selectively obtained as necessary. When the obtaining of the information on "only the flatness" is aimed at, the material to be measured need not necessarily be limited to the "steel", and any material to be measured will do, only if the material to be measured gives some influence on the mutual induction effect between the exciting coil and the detecting coils. In consequence, when only the information on the flatness as described above is required, the tenm "steel" is reread as "a steel or any other material having in its composition a material giving an influence on the mutual induction efEect between the excitin~ coil and the detecting coils" i.e. "magnetic material", including the term used in the ~0 claims. Needless to say, when either one of the information is required, it suffices only if the information on the aforesaid either one of the information is outputted.
Description will hereunder be given of the preferable specific form in the stage of specifically working the present invention.
Firstly, the arrangement of the detecting coils and the exciting coil will be described. Fig. 4 shows the second o~
embodiment of the present invention, which is identical in basic arrangement with the first embodiment shown in Fig. 2, however, the detecting coil 151 is disposed concentrically with the exciting coil 13. Fig. 5 shows the detecting accuracy of the lift-off L when the distance D2 between the exciting coil 13 and the detecting coil 152 is varied in some way or other in the detecting system shown in Fig. 4. As apparent from this, when D2 is less than 20 mm ox beyond 200 mm, the detecting accuracy of the lift-off L tends to be deteriorated, and consequently, it is found that there is em optimum range for D2 to obtain the satisfactory detecting accuracy. The above-described tendency is true of the detecting accuracy of the transformation value.
It is appreciated that this is because of the following reasons.
Namely, when D2 is beyond 200 mm, the detecting signal 162 of the detecting coil 152 as shown in Fig. 4 becomes considerably snkall in magnitude, whereby the detecting signal is easily subjected to an influence of noises and the like, so that the S/N ratio is deteriorated. Whereas, when D2 is less than 20 mm, the difference in the ways o sensitivity to the transformation value and the lift-off L at the detecting coils 151 and 152 as shown in Fig. 4 becomes very low, whereby it becomes difficult to separate the transformation value and the lift-off L from the detection signals l61 and 162 for quantitative measuring, so that the detecting accuracy is deteriorated. As apparent from the above knowledge, according to the present invention, it is preferable that the detecting coils are disposed within a range of radially 200 mm from the center of the exciting coil in a ~6C~06~
manner to be spaced 20 mm or ~lore apart from each other.
Description will now be given of the effect of the cores.
As one of its drawbacks, the magnetio detecting system has the general characteristics of that the magnitudes of the detection signals become smaller in an inverse proportion to the increase of the li~t-off, whereby the range of detectable lift-off is restricted. It goes without saying that, when the magnetic detecting system is applied to the actual manufacturing line, it is preferable that the above-described range is as large as pos~ible from the viewpoint of not only the detecting accuracy but also the heat resistance of the detecting system, the conveyance characteristics, the shape and the like of the material to be measured. The present invention has been developed under deep studies in view of the above respects, with lS the result that it has been found that the independent cores for exclusive use are provided in the exciting coil and the detecting coils as necessary, so that the magnitudes of the detection signals in the same lift-off can be increased to a considerable extent.
Figs. 6 to 8 show the third to fifth embodiments of the present invention, where the cores are provided in some coils, respectively. Fig. 6 shows the case where a rod-shaped core 90 is provided in the exciting coil 13, and Fig. 7 shows the case where rod-shaped cores l9o, 191 and 192 are provided in the exciting coil 13, the detecting coils 151 and 152, respectively.
Fig. 8 shows the case where the exciting coil 13, the detecting coils 151 and 152 are connected to one another by an E-shaped ~ 2 ~
core 193. Fig. 9 shows that the magnitudes of the detection signals 162 detected by the respective detecting systems shown in Fig. 2 and Figs~ 6 to 8 are compared with the magnitude of the detection signal 162 as being the reference at the detecting coil 152 under the same conditions where the transformation rate gamma phase - alpha phase of the steel 1 is 100% and the lift-off L is 100 mm, by use of the detecting system of the second embodiment shown in Fig. 4. Additionally, the results shown in Fig. 9 are obtained under the same conditions except those relating to the core or cores.
Fig. 9 makes it clear that the magnitude of the detection signal 162 tends to increase in the case where the rod-shaped core 19o is provided in the exciting coil 13 in Fig. 6 (the third embodiment) and also in the case where the rod-shaped cores l9o, 191 and 192 are provided in the exciting coil 13, the detecting coil 151 and 152, respectively, in Fig. 7 (the fourth embodiment) as compared with the case where no core is provided as in Fig. 4 (the second embodiment). In consequence, it is found that the provision of the rod shaped cores 19o ~ 192 makes it possible to improve the detecting accuracy in the region where the lift-off L is large. Additionally, in the case of the fifth embodiment where the E-shaped core 193 shown in Fig. 8 is provided, within the range of the lift-off L of 50 mm or less, the magnitude of the detection signal 162 is large as compared with other embodiments of the present invention. However, as the lift-off L increases beyond 50 mm, the magnitude of the detection signal 162 sharply decreases in magnitude. As ~0~64L
apparent from Fig. 9, it is recognized that the magnitude of the detection signal 162 rather decreases in the conditions where the lift-off is 100 m~. In consequence, this fifth embodiment proves to work satisfactorily when applied to a relatlvely small-si~ed line where the steel 1 as being the material to be measured has a satisfactorily good flatness.
Description will hereunder be given of the preferable exciting conditions in t:he present invention. As well known tody, penetrating depth of the magnetic flux into the magnetic matexial largely depends upon the frequency of the magnetic flux. In other words as the exciting frequency of the exciting coil in the detecting system becomes higher, the penetrating depth into the material to be measured decreases. Now, it is known that, in general, the steel after the hot rolling shows a peculiar transformation behavior under the surface layer due to the influence of the temperature distribution, the rolling or the like, the detection information as described above in such a peculiar region as described above tends to reduce the significance in relating the steel to the material quality in the final product. In conse~uence, during measurements, it is desired to make the exciting conditions of the detecting system proper. According to the researches made by the inventors of the present invention, the region, in which the transformation characteristics of the hot-rolled steel shows the peculiar behavior, is within a range of about 200 micro meters under the surface layer. In order to avoid it, it is desirable to make the penetrating depth of the magnetic flux to be 200 micro ~ 6~
meters or more. So, it is desirable to rnake the frequency of the exciting current in the detecting system to be 10KHz or less in view of the above. Namely, the lower the frequency becomes, the larger the penetrating depth of the magnetic flux becomes, and accordingly, the information on the transformation value detected becomes more macroscopic. On the other hand, there are presented such drawbacks as the deterioration in the speed of response of the detecting system and the lowering of the S/N
ratio of the detection signals. In order to avoid the above-described drawbacks, it is desirable that the exciting frequency is not less than 5Hz. The most preferable range of the exciting frequency is 30Hz - lKHz.
It should be apparent to those skilled in the art that the above-described emgodiments are merely representative, which represent the applications of the principles of the present invention. Numerous and varied other arrangements can be readily devised by those skilled in the art without departing frorn the spirit and the scope of the invention.
Backed by the tendency of manufacturing cost reduction of steel products, recently, there has been activated the utilization of the transformation structure strengthening technique through the controlled cooling after the hot rolling as a measure of manufacturing a higher strength steel in a hot rolled state, using a steel blank having low alloy contents.
Now when the transformation structure strengthening technique is utilized, needless to say, it is necessary to have accurate knowledge about the transformation behavior of steel.
As for the transformation behavior, ones which have been studied in the experimental manners in a laboratory, in general.
However, in many cases, ones which are manufactured by an actual system are different from the results of experiments in the laboratory to a considerable extent. Although the actural .~.
conditions have not been fully grasped yet, one of the reasons for the difference of the transformation behavior in the actual system from the results of experiments in the laboratory is said to be that the transformation behavior is complicatedl~ varied depending upon the history of thermal strains and the like in the preceding process or an upstream process. In consequence, for example, (A) as a measure of grasping the variations in a local transformation behavior due to a difference in the histories of rolling temperature to improve the homogeneity in the material on the longitudinal and widthwise directions, which is a major factor governing the matexial quality of a hot-tolled steel, (B) as a measure of grasping a ratio between gamma phase and alpha phase at the time of appl~ing the reduction to manufacture a steel having a high strength and being excellent lS in toughness, e. g. a steel plate for a high tension line pipe, or (~) as a measure of grasping a ratio of gamma phase and alpha phase at the time of starting the quenching in the manufacturing technique of a mix~d structure steel to manufacture a thin steel plate having a high strength and being excelle~t in workability, if online information about the transformation behavior of steel would be precisely detected, then a great profit would be expected in the field of manufacturing various steels, where a hot rolling line and a heat treating line are used.
Heretofore, there has been proposed the following method as 2S a method of online-detecting the above-described transformation behavior of steel. One of those is a method wherein the rise in temperature due to the latent heat at the time of the phase ~26(~06~L
transformation is detected by a thermometer installed on a manufacturing line to grasp a transformation behavior as described in Japanese patent publication No. 24017/81 for example. However, this method is disadvantageous in that obtainable information is gi~en in excessively broad outline, the response is slow and the thermometer is used as a sensor, with the result that the measurement during water cooling cannot be conducted.
Forthermore, as described in Japanese patent laid-open Nos.
114518/74, 136442/76 and Japanese patent puhlication No.
25309/78, there have been proposed methods, in which X-rays are irradiated onto the surface of a steel, and the transformation value is measured from a difraction strength. However, this method is disadvantageous in that it is necessary to take safety protective measure from the X-ray injuries since strong X-rays are irradiated, and consequently, the detection system itself becomes large-sized, resulting in increased installation cost, a limited installed number, occurrence of maintenance problems and the like. Additionally, since the obtainable information remains within the surface layer portion of about 50 micro meters or less o~ the material to be measured, it is difficult that the obtainable information can be used as a macroscopic information.
In contrast thereto, there have been proposed methods of detecting the transformation behavior by use of a magnetic detector, utilizing the fact that the transformation from gamma phase to alpha phase of steel is accompanied by a physical ~26~)~J16~L
phenomenon of a change from the paramagnetism (gamma phase) to the ferromagnetism ~alpha phase). For example, Japanese patent laid-open Nos. 104754/75 and 82443/81 correspond to these proposals. These methods are problematical in that the measurable temperature range is limited to a temperature region of the Curie point or less of the steel to be measured.
However, in most cases, the Curie points of ordinary commercial steels are as high as about 750C. In contrast thereto, the range of transformation o the steel during cooling process is transfered in non-e~uilibrium condition to the low temperature side, whereby the most part of transformation proceeds within a temparature range of the C'urie point or less, so that these methods are advantageous in that the above-mentioned problems do not impose practical obstacles except some types of steels, are used easier in practice and the response is good as compared with other methods not utili~ing the aforesaid magnetic means, moreover, the measurements are practicable during wat~r cooling and so on, thereby proving to be practical and effective methods. Although the magnetic detecting systems proposed by Japanese patent laid-open Nos. 104754/75 and 82448/81 have the following problems not solved yet, it cannot be said that those detecting systems are satis~actorily practicable.
Firstly, description will be given of Japanese patent laid-open No. 104754/75. This proposal relates to a hot rolling method utilizing a magnetic detecting system, not relating to the magnetic detecting system itself, thus the details about the fuctions and construction of the detecting system in the ~2~0~
practical use are unclear. However, according to the description in the specification of the proporal, an excited pickup coil is placed close to the steel to be measured, and the presence of transformation is qualitatively detected from a change in impedance of the pickup coil itself generated due to the transformation of the steel to be measured from gamma phase to alpha phase. However, in order to apply the proposal to the manufacturing field of steel as aforesaid, it is necessary to have a function capable of quantitatively detecting the progress of transformation as the function of the magnetic detecting device. With the detecting device capable of only qualitatively detecting the presence of the transformation as described in the proposal, it should be said that the value of application is low.
Description will now be given of Japanese patent laid-open No. 82443/81. Fig.l is a block diagram showing the arrangement of the magnetic detecting system in this proposal. This magnetic detecting system is of such an arrangement that an exciting coil 3 wound around a magnetic pole 2 composed by a U-shaped iron core and magnetic flux detector 6 are spaced a predetermined distance Ls from each other, interposing a steel 1 as being a material to be measured therebetween, and the exciting coil 3 is excited by an exciting device 4, whereby, out of magnetic fluxes 5 generated by the excitation, the intensity of a magnetic flux 5O which penetrates through the steel 1 and is leaked to reach the flux detector 6 is detected. The transformation value is detected from a change in intensity of _ 5 _ ~0C~6~L
the flux 5O generated in accordance with a transformation value in the steel 1. In the drawing, designated at 7 i5 a thermometer, 8 an arithmetic unit, and 9 condition signals of the material, of plate thiclcness and the like. Although this method has a function capable of quantitatively measuring the transformation value in principles as compared with the aforesaid Japanese patent laid-open No. 104754/75, it has the following disadvantages in the application to an actual manufacturing line.
Namely, in the above arrangement, the intensity of the magnetic flux 5O (magnetic flux density) is substantially inversely proportional to the distance Ls between the magnetic pole 2 and the magnetic flux detector 6, and hence, in order to detect the transformation value with satisfactory accuracy, it is necessary to make the distance Ls to be at least about 150 mm or less. However, it should be said that it is extremely difficult to move the steel 1 through such a narrow gap without contacting the magnetic flux detector 6 in the application of the proporal to the actual manufacturing line. ~his is because that a hot-rolled steel plate manufactured in a hot strip mill and plate mill for example has a buckling, camber, waving and/or the like in the shape of after hot rolling, should not necessarily be fla~t, particularly this tendency is strong in the forward end, rear end and therearound of the rolled steel and ~5 hence, contact of the detector 6 with the steel 1 is inevitable during conveyance of the steel. In order to avoid such an accident, there is proposed such a method that the aforesaid gap ~l2~064 is temporarily expanded during the passing therethrough by the forward end or rear end portion of the steel for example.
H~wever, the variability in material quality tends to occur in the forward end, rear end portion or therearound, and hence, if it is impossible to detect these portions, then the value of installing the detecting device should be lost by half.
Furthermore, the magnetic detecting system of the proposal is disadvantageous in that, since a vacant space portion in a magnetic circuit through which the magnetic fluxes 5 are passed is varied depending upon the difference in plate thickness t of the steel 1 as being the material to be measured, it is necessary to correct a det:ection output by the plate thickness t, further, the measuring accuracy depends upon the actual plate thickness t, and so on. However, the plate thickness t of the steel 1, which is rolled by an ordinary hot rolling mill is widely varied in such ways as 1.2 - 30 mm in a hot strip mill and 5.0 - 300 mm in a plate mill for e~ample. The correcting operations are complicated, and it is difficult Erom the viewpoint of the characteristics of the conveyance of the steel 1 to substantially obtain the proper detecting accuracy in accordance with the actual plate thickness t.
As described above, it should be said that the magnetic detecting system proposed by Japanese patent laid-open No.
82~43/81 has many problems in the application to the actual manufacturing line.
SUM~RY OF THE INVENTION
The present invention has been developed to obviate the ~ 2t~(~06~
-above-described dlsadvantages of -the prior art and has as its Eirst object the prov:ision oE a magnetic detecting system being multiply functional, wherein a transformation value of a steel, which has not been detectable by the conven-tional method, is precisely detected, and fur-ther, even the fla-tness of lhe steel can be detected with high accuracy at the same time.
A second object of -the present invention is to provide a magnetic detecting system capable of de-tect-ing the flatness of a rnagnetic material with high accu-racy.
According to the presen-t invention, there is provided a system for online-detection of either a -trans-formation value and a flatness of a s-teel or one of said transforma-tion valve and flatness,comprising:
an exciting coil located at a spaced distance from one side of a surface of the steel and capable of generating alternating magnetic fluxes by alternating current excitations;
at least -two detecting coils arranged on a same side and at substantially a same spaced distance from said s-teel as said exciting coil, said detecting coils being arranged at positions different in distance from said exciting coil in a direc-tion parallel to -the sur-face of said steel, and having induced vol-tages due to the magnetic fluxes generated by said exciting coil;
and an ari-thmetic uni-t for calculating and outputt-ing ei-ther the -transformation value and the flatness of said steel or one of said transformation value and flat-ness, said arithmetic unit being independently electri-cally coupled with each of said detecting coils such that values of -the induced voltages in the detectin~ coils are input into said arithmetic unit and at least one of 06a~
- 8a -the -transEorma-tion value and the fla-tness of saicl steel is calculated by the ari-thmetic unit in accordance with a predetermined formula using the values oE the induced voltages.
A specific Eorm of the present invention is of such an arrangement that the two or more detec-ting coils are disposed _ _ _ ~l26~)0~
within a range of 2~0 mm or less from the exciting coil, respectively, and spaced 20 mm or more apart from each other, so that high detectin~ accuracy can be reliably obtained.
Another specific form of the present invention is of such an arrangement that one of the detecting coils is disposed concentrically with the exciting coil, so that a space for installation can be minimized.
A further specific form of the present invention is of such an arrangement that at least one coil out of the exciting coil and the detecting coils is provided therein with a core Eor exclusive use, which does not stride over any one of other coils, so that magnitudes of detection signals can be greatly increased.
A still further specific form of the present invention is of such an arrangement that only the exciting coil is provided therein with a rod-shaped core, so that the exciting magnetic field is increased in its intensity.
A still further specific form of the present invention is of such an arrangement that independent rod-shaped cores are provided in all of the exciting coil and the detecting coils, respectively, so that the magnitudes of the detection signals can be maximised.
A still further specific form of the present invention is of such an arrangement that all of the exciting coil and the detecting coils are co~monly provided with a comb-shaped core striding over all of the coils, so that the installation work can be facilitated.
6~
A s-till Eurther specific Eorm of the present invention is of an arrangement that a Erequency o:E excit-ing current applied to the exciting coil i.s held w:ithin a range of 5~1z - 10 KH~ so that the suitable penetrating depth of magnetic fluxes, the good response speed of the detecting device, -the high S/N ratio (Signal to Noise ratio) between the de-tection signals and the like can be obtained respectively.
According -to -the present invention, there is also provided a system for online-detec-tion of a flatness of a magnetic materia~,comprising:
an exciting coil located at a spaced dis-tance from one side of a surface of the magnetic ma-terial and capable of generating alternating magnetic fluxes by al-ternating current excitations;
at least -two detecting coils arranged on a same side and at substantially a same spaced distance from said magneti.c ma-terial as said exciting coil, said detect-ing coils being arranged at positions different in dis-tance from said exciting coil in a direction parallelto the surface of said magnetic material, and having in-duced vol.tages due to -the magnetic fluxes genera-ted by said exciting coil; and an arithmetic unit for calculating and outputt-ing the flatness of said magnetic material, said arith-metic unit being independently electrically coupled with each of said detecting coils such that values of -the in-duced voltages in the detecting coils are inpu-t in-to said arithmetic unit and the flatness of said magnetic material is calculated by the arithmetic unit in accordance with a predetermined formula using the values of -the induced voltages.
As described above, according to the presen-t inven-tion, two or more de-tec-ting coils are arranged on ~6~6a~
- lOa -the same side as the exciting coil and at positions diE-ferent in distance from the excit:ing coll and the trans-formation value and the Elatness (lift-ofE) of a steel as being the material -to be measured are simultaneously sought by the detec-tiny signals, so that the _ ~6C)1~:36~
following advantages are ohtainable.
~A) The mutual induction by the magnetism is utilized for the detection, so that the detection is accurate, the response is good and the system is excellent as quantitative detecting S means in online.
(B) The components of the detecting system can be concentrically disposed on one side of the material to be measured, so that, even in the manufacturing line where the flatness of the material is not so good, the system is satisfactorily practicab:LeO
(C) Although the cor,lponents are disposed at one side of the material, the transformation value of the steel can be detected with the system not being subjected to the influence of the fluctuations in lift-off.
(D) The online in~ormation on the lift-off, i.e. the flatness of the material can be collectively or singly detected.
(E) While the flatness of the material can be detected by the magnetic detection, the system is not subjected to the influence of the transformation value of the steel.
(F) The system is widely usable in the various cases including ambient conditions of high temperature, under water and the like.
In consequence, not only the online detection of the transformation value of the steel in the various hot rolling processes and heat treatment processes, but also the online detection of the flatness are simultaneously conducted.
Further, the detection should not necessarily be limited to the - 11 ~
steel, only if the material to be measured may give some influence to the mutual induction between the exciting coil and the detecting coils, the flatness of t:he material to be measured can be online-detected irrespective of the presence of the transformation behavior. Thus, the system can be applied to uses of a very wide range.
BRIEF DESCRIPTION OF TH.~ DRAWINGS
. .
The exact nature of this invention, as well as other objects and advantages therof, will be readily apparent from consideration of the following specification relating to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the ~igures thereof and wherein:
Fig. 1 is a partially sectional block diagram showing the conventional example of the magnetically measuring type transformation value detecting system;
Fig. 2 is a block diagram corresponding to Fig. 1, showing a first embodiment of the present invention:
Fig. 3 is a chart showing the interrelation of the increase or decrease of the lift-off and transformation value with the detection signals at the detecting coils, in explanation of the principles of the present invention;
Fig. 4 is a block diagram corresponding to Fig. 2, showing a second embodiment of the present invention;
Fig. 5 is a chart showing the relationship of the intervals between the detecting coils with the measuring errors in lift-off;
Figs. 6 to 8 are block diagrams corresponding to Fig. 2, ~X6(~06~
showing a third to a fifth embodiments of the present invention;
and Fig. 9 is a chart showing the relationship of the respective embodiments with the second embodiment about the magnitudes of the detection signals when the core is provided in the exciting coil or the detecting coils.
DETAILED DESCRIPTION OF THE INVENTION
Detailed description will hereunder be given of the present invention with reference to the accompanying drawings.
Fig. 2 shows the first embodiment of the present invention.
In the drawing, designated at 1 is a steel being the material to be measured, 12 an alternating current (AC) exciting device, 13 an exciting coil, and 151 and 152 detecting coils disposed at positions different in distance (Dl and D2) from the exciting coil 13. Denoted at 141 is a magnetic flux generated at the exciting coil 13 and interlinked with the detecting coil 151 through the steel 1 and 142 a magnetic flux interlinked with the detecting coil 152.
Now, such a state stands here that the steel 1 does not begin to transform, i.e. the paramagnetic condition, in which the steel 1 is in the single gamma phase. In this state thereinafter referred to as "the initial state"), the magnetic fluxes 141 and 142 interlinked with the detecting coils 151 and 152 have predetermined intensities corresponding to the distances Dl and D2 from the exciting coil 13 and induced voltages propostional to the predetermined intensities, respectively.
~L2~6~
When the steel 1 begins to transform from gamma phase to alpha phase and a paramagnetic alpha phase precipitates, the alpha phase is magnetized, fluctuations are caused to the intensity of magnetic field of the steel 1, and the intensities of the magnetic fluxes 141 and 142 are shifted f.rom the initial st~te ! whereby the resu:l.ts are detected as the changes in the induced voltages in the detecting coils 151 and 152.
Furthermore, when a ~istance L between the steel 1 and the exciting coil 13 (hereinafter referred to as a "lift-off", and measuring the lift-off means measuring the flatness) is varied, the induced voltages at the detecting coils 151 and 152 are changed, respectively Detection signals 161 and 162 thus obtained at the detecting coils 151 and 152 are delivered to an arithmetic unit 17, where the magnitudes of the signals measured at the detecting coils 151 and 152 are compared, and a transformation value and a lift-off L are separately calculated in accordance with the relationship to be described hereunder, which is previously stored in the arithmetic unit 17.
Description will now be given of a technique of obtaining 2~ the transformation value in the steel 1 and the lift-off L from the magnitudes of the detection signals 161 and 162 of the detecting coils 151 and 152.
Fig. 3 shows the relationship between the detection signals ~vaxied values in the induced voltages from the initial state ) of the detecting coils 151 and 152 when the gamma to alpha transformation value of the steel 1 and the lift-off L are varied in a detecting system basically following the arrangement ~LZ~) [)6~
shown in Fig. 2, wherein the diskance Dl from the exciting coil 13 to the detecting coil 151 is made to be 50 mm and the distance D2 from the exciting coil 13 to the detecting coil 152 is made to be 100 mm. In Fig. 3, those indicated by broken S lines are relationships in the cases where the transformation values are at constant ~alues and only the lift-off L is varied, and those indicated by solid lines are relationships in the cases where the lift-of L are at constant values and only the transformation value is varied. As apparent from Fig. 3, the relationship in magnitude between the detection signals 161 and 162 of the detecting coils 151 and 152 assumes a curved line as shown in 0 - a - b - c - d - e - f when the lift-off L is varied, whereas the aforesaid relationship assumes a generally stxaight line as shown in 0 - j - i - h - g - f when the transformation value is varied. Namely, it is found that vector quantities determined by the detection signals 161 and 162 of the two detecting coils 151 and 152 have intrinsic relationships with the transformation value and the lift-off I" respectively.
In consequence, the precise relationships shown in Fig. 3 are previously obtained, stored in the arithmetic unit 17 shown in Fig. 2, and compared with the detection signals 161 and 162 detected by the detecting coils 151 and 152 for calculaticn, so that the transformation value and the lift-off L can be simultaneously obtained.
In the foregoing, description has been given of the case where two detecting coils are used. It is natural that the same thing should be true of the cases where the number of the ~ 26C~
detecting coils are more than two. Needless to say, the number of the detecting coils i5 increased, whereby measurements by use of three or four detecting coils are conducted, so that a further precise measurement can be accomplished. As apparent from the above description, according to the present invention with the above-described arrangexnent, information on "only the transformation value", "the transformation value and the flatness" or "only the flatness" can be selectively obtained as necessary. When the obtaining of the information on "only the flatness" is aimed at, the material to be measured need not necessarily be limited to the "steel", and any material to be measured will do, only if the material to be measured gives some influence on the mutual induction effect between the exciting coil and the detecting coils. In consequence, when only the information on the flatness as described above is required, the tenm "steel" is reread as "a steel or any other material having in its composition a material giving an influence on the mutual induction efEect between the excitin~ coil and the detecting coils" i.e. "magnetic material", including the term used in the ~0 claims. Needless to say, when either one of the information is required, it suffices only if the information on the aforesaid either one of the information is outputted.
Description will hereunder be given of the preferable specific form in the stage of specifically working the present invention.
Firstly, the arrangement of the detecting coils and the exciting coil will be described. Fig. 4 shows the second o~
embodiment of the present invention, which is identical in basic arrangement with the first embodiment shown in Fig. 2, however, the detecting coil 151 is disposed concentrically with the exciting coil 13. Fig. 5 shows the detecting accuracy of the lift-off L when the distance D2 between the exciting coil 13 and the detecting coil 152 is varied in some way or other in the detecting system shown in Fig. 4. As apparent from this, when D2 is less than 20 mm ox beyond 200 mm, the detecting accuracy of the lift-off L tends to be deteriorated, and consequently, it is found that there is em optimum range for D2 to obtain the satisfactory detecting accuracy. The above-described tendency is true of the detecting accuracy of the transformation value.
It is appreciated that this is because of the following reasons.
Namely, when D2 is beyond 200 mm, the detecting signal 162 of the detecting coil 152 as shown in Fig. 4 becomes considerably snkall in magnitude, whereby the detecting signal is easily subjected to an influence of noises and the like, so that the S/N ratio is deteriorated. Whereas, when D2 is less than 20 mm, the difference in the ways o sensitivity to the transformation value and the lift-off L at the detecting coils 151 and 152 as shown in Fig. 4 becomes very low, whereby it becomes difficult to separate the transformation value and the lift-off L from the detection signals l61 and 162 for quantitative measuring, so that the detecting accuracy is deteriorated. As apparent from the above knowledge, according to the present invention, it is preferable that the detecting coils are disposed within a range of radially 200 mm from the center of the exciting coil in a ~6C~06~
manner to be spaced 20 mm or ~lore apart from each other.
Description will now be given of the effect of the cores.
As one of its drawbacks, the magnetio detecting system has the general characteristics of that the magnitudes of the detection signals become smaller in an inverse proportion to the increase of the li~t-off, whereby the range of detectable lift-off is restricted. It goes without saying that, when the magnetic detecting system is applied to the actual manufacturing line, it is preferable that the above-described range is as large as pos~ible from the viewpoint of not only the detecting accuracy but also the heat resistance of the detecting system, the conveyance characteristics, the shape and the like of the material to be measured. The present invention has been developed under deep studies in view of the above respects, with lS the result that it has been found that the independent cores for exclusive use are provided in the exciting coil and the detecting coils as necessary, so that the magnitudes of the detection signals in the same lift-off can be increased to a considerable extent.
Figs. 6 to 8 show the third to fifth embodiments of the present invention, where the cores are provided in some coils, respectively. Fig. 6 shows the case where a rod-shaped core 90 is provided in the exciting coil 13, and Fig. 7 shows the case where rod-shaped cores l9o, 191 and 192 are provided in the exciting coil 13, the detecting coils 151 and 152, respectively.
Fig. 8 shows the case where the exciting coil 13, the detecting coils 151 and 152 are connected to one another by an E-shaped ~ 2 ~
core 193. Fig. 9 shows that the magnitudes of the detection signals 162 detected by the respective detecting systems shown in Fig. 2 and Figs~ 6 to 8 are compared with the magnitude of the detection signal 162 as being the reference at the detecting coil 152 under the same conditions where the transformation rate gamma phase - alpha phase of the steel 1 is 100% and the lift-off L is 100 mm, by use of the detecting system of the second embodiment shown in Fig. 4. Additionally, the results shown in Fig. 9 are obtained under the same conditions except those relating to the core or cores.
Fig. 9 makes it clear that the magnitude of the detection signal 162 tends to increase in the case where the rod-shaped core 19o is provided in the exciting coil 13 in Fig. 6 (the third embodiment) and also in the case where the rod-shaped cores l9o, 191 and 192 are provided in the exciting coil 13, the detecting coil 151 and 152, respectively, in Fig. 7 (the fourth embodiment) as compared with the case where no core is provided as in Fig. 4 (the second embodiment). In consequence, it is found that the provision of the rod shaped cores 19o ~ 192 makes it possible to improve the detecting accuracy in the region where the lift-off L is large. Additionally, in the case of the fifth embodiment where the E-shaped core 193 shown in Fig. 8 is provided, within the range of the lift-off L of 50 mm or less, the magnitude of the detection signal 162 is large as compared with other embodiments of the present invention. However, as the lift-off L increases beyond 50 mm, the magnitude of the detection signal 162 sharply decreases in magnitude. As ~0~64L
apparent from Fig. 9, it is recognized that the magnitude of the detection signal 162 rather decreases in the conditions where the lift-off is 100 m~. In consequence, this fifth embodiment proves to work satisfactorily when applied to a relatlvely small-si~ed line where the steel 1 as being the material to be measured has a satisfactorily good flatness.
Description will hereunder be given of the preferable exciting conditions in t:he present invention. As well known tody, penetrating depth of the magnetic flux into the magnetic matexial largely depends upon the frequency of the magnetic flux. In other words as the exciting frequency of the exciting coil in the detecting system becomes higher, the penetrating depth into the material to be measured decreases. Now, it is known that, in general, the steel after the hot rolling shows a peculiar transformation behavior under the surface layer due to the influence of the temperature distribution, the rolling or the like, the detection information as described above in such a peculiar region as described above tends to reduce the significance in relating the steel to the material quality in the final product. In conse~uence, during measurements, it is desired to make the exciting conditions of the detecting system proper. According to the researches made by the inventors of the present invention, the region, in which the transformation characteristics of the hot-rolled steel shows the peculiar behavior, is within a range of about 200 micro meters under the surface layer. In order to avoid it, it is desirable to make the penetrating depth of the magnetic flux to be 200 micro ~ 6~
meters or more. So, it is desirable to rnake the frequency of the exciting current in the detecting system to be 10KHz or less in view of the above. Namely, the lower the frequency becomes, the larger the penetrating depth of the magnetic flux becomes, and accordingly, the information on the transformation value detected becomes more macroscopic. On the other hand, there are presented such drawbacks as the deterioration in the speed of response of the detecting system and the lowering of the S/N
ratio of the detection signals. In order to avoid the above-described drawbacks, it is desirable that the exciting frequency is not less than 5Hz. The most preferable range of the exciting frequency is 30Hz - lKHz.
It should be apparent to those skilled in the art that the above-described emgodiments are merely representative, which represent the applications of the principles of the present invention. Numerous and varied other arrangements can be readily devised by those skilled in the art without departing frorn the spirit and the scope of the invention.
Claims (9)
1. A system for online-detection of either a transformation value and a flatness of a steel or one of said transformation value and flatness, comprising:
an exciting coil located at a spaced distance from one side of a surface of the steel and capable of generating alternating magnetic fluxes by alternating current excitations;
at least two detecting coils arranged on a same side and at substantially a same spaced distance from said steel as said exciting coil, said detecting coils being arranged at positions different in distance from said exciting coil in a direction parallel to the sur-face of said steel, and having induced voltages due to the magnetic fluxes generated by said exciting coil;
and an arithmetic unit for calculating and outputt-ing either the transformation value and the flatness of said steel or one of said transformation value and flat-ness, said arithmetic unit being independently electri-cally coupled with each of said detecting coils such that values of the induced voltages in the detecting coils are input into said arithmetic unit and at least one of the transformation value and the flatness of said steel is calculated by the arithmetic unit in accordance with a predetermined formula using the values of the induced voltages.
an exciting coil located at a spaced distance from one side of a surface of the steel and capable of generating alternating magnetic fluxes by alternating current excitations;
at least two detecting coils arranged on a same side and at substantially a same spaced distance from said steel as said exciting coil, said detecting coils being arranged at positions different in distance from said exciting coil in a direction parallel to the sur-face of said steel, and having induced voltages due to the magnetic fluxes generated by said exciting coil;
and an arithmetic unit for calculating and outputt-ing either the transformation value and the flatness of said steel or one of said transformation value and flat-ness, said arithmetic unit being independently electri-cally coupled with each of said detecting coils such that values of the induced voltages in the detecting coils are input into said arithmetic unit and at least one of the transformation value and the flatness of said steel is calculated by the arithmetic unit in accordance with a predetermined formula using the values of the induced voltages.
2. A system for online-detection as set forth in claim 1, wherein said at least two detecting coils are disposed within a maximal range of 200 mm from said exciting coil, respectively, and at least spaced 20 mm apart from each other.
3. A system for online-detection as set forth in claim 1, wherein one of said detecting coils is dis-posed concentrically with said exciting coil.
4. A system for online-detection as set forth in claim 1, wherein at least one of said exciting coil and said detecting coils is provided therein with a core which is not connected with any one of other coils.
5. A system for online-detection as set forth in claim 4, wherein a rod-shaped core is provided only in said exciting coil.
6. A system for online-detection as set forth in claim 4, wherein independent rod-shaped cores are pro-vided in all of said exciting coil and said detecting coils, respectively.
7. A system for online-detection as set forth in claim 1, wherein said exciting coil and said detecting coils are commonly provided with a comb-shaped core con-nected to all of said coils.
8. A system for online-detection as set forth in claim 1, wherein a frequency of exciting current ap-plied to said exciting coil is held within a range of 5 Hz-10KHz.
9. A system for online-detection of a flatness of a magnetic material,comprising:
an exciting coil located at a spaced distance from one side of a surface of the magnetic material and capable of generating alternating magnetic fluxes by al-ternating current excitations;
at least two detecting coils arranged on a same side and at substantially a same spaced distance from said magnetic material as said exciting coil, said detect-ing coils being arranged at positions different in dis-tance from said exciting coil in a direction parallel to the surface of said magnetic material, and having in-duced voltages due to the magnetic fluxes generated by said exciting coil; and an arithmetic unit for calculating and outputt-ing the flatness of said magnetic material, said arith-metic unit being independently electrically coupled with each of said detecting coils such that values of the in-duced voltages in the detecting coils are input into said arithmetic unit and the flatness of said magnetic material is calculated by the arithmetic unit in accordance with a predetermined formula using the values of the induced voltages.
an exciting coil located at a spaced distance from one side of a surface of the magnetic material and capable of generating alternating magnetic fluxes by al-ternating current excitations;
at least two detecting coils arranged on a same side and at substantially a same spaced distance from said magnetic material as said exciting coil, said detect-ing coils being arranged at positions different in dis-tance from said exciting coil in a direction parallel to the surface of said magnetic material, and having in-duced voltages due to the magnetic fluxes generated by said exciting coil; and an arithmetic unit for calculating and outputt-ing the flatness of said magnetic material, said arith-metic unit being independently electrically coupled with each of said detecting coils such that values of the in-duced voltages in the detecting coils are input into said arithmetic unit and the flatness of said magnetic material is calculated by the arithmetic unit in accordance with a predetermined formula using the values of the induced voltages.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000465120A CA1260064A (en) | 1984-10-10 | 1984-10-10 | System for online-detecting transformation value and/or flatness of steel or magnetic material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000465120A CA1260064A (en) | 1984-10-10 | 1984-10-10 | System for online-detecting transformation value and/or flatness of steel or magnetic material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1260064A true CA1260064A (en) | 1989-09-26 |
Family
ID=4128888
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000465120A Expired CA1260064A (en) | 1984-10-10 | 1984-10-10 | System for online-detecting transformation value and/or flatness of steel or magnetic material |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1260064A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110799838A (en) * | 2017-06-28 | 2020-02-14 | 杰富意钢铁株式会社 | Method and apparatus for measuring magnetic transformation ratio of steel sheet in annealing furnace, continuous annealing process, and continuous hot-dip galvanizing process |
-
1984
- 1984-10-10 CA CA000465120A patent/CA1260064A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110799838A (en) * | 2017-06-28 | 2020-02-14 | 杰富意钢铁株式会社 | Method and apparatus for measuring magnetic transformation ratio of steel sheet in annealing furnace, continuous annealing process, and continuous hot-dip galvanizing process |
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