JPH05285720A - Quality judging method in steel plate manufacture line - Google Patents

Abstract

PURPOSE:To eliminate necessity of sampling for a test and of a mechanical test off-line and reduce the cost for the test drastically by installing a non- contact type Young's modulus measuring device on steel plate manufacture line and cutting and removing automatically the parts whose Young's modulus is detected to be defective. CONSTITUTION:A Young's modulus measuring device 4 is installed on a steel plate manufacture line. The quality Young's modulus of the whole steel is detected on-line and the parts whose quality is detected to be defective is cut off with a shear 5. Therefore steel plate sampling works is eliminated, defective parts in whole steel plates are cut off in just one processing, time required for a test is shortened, and the cost for the test is reduced drastically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material determination method for removing defective portions of a steel sheet in a steel sheet production line.

[0002]

2. Description of the Related Art Conventionally, in a steel sheet manufacturing line, after rolling a steel sheet in a cold rolling process and then an annealing process, the steel sheet is shipped as a finished product, but it is necessary to guarantee the mechanical quality of the shipped steel sheet. Therefore, it is often the case that a sample is cut out from a product steel sheet and a tensile test of the sample is performed off-line to check for the presence or absence of quality defects.

[0003]

As a result of testing a sample, the mechanical properties of the steel sheet, that is, the yield point stress YP (index of workability), the maximum tensile strength TS (index of workability), and the elongation E1.
If the (index of ductility) and the Rankford value Rf (index of deep drawing workability) deviate from the specifications, after cutting a certain length from the steel plate, the sample must be cut out from the steel plate again and the test must be repeated. Therefore, high cost is required for quality assurance, and shipment may be delayed due to testing. In addition, even if the quality of the sample is within the specified value,
It cannot be said that the quality is within the specified value over the entire length of the coil of the steel sheet, and in the user who uses the delivered steel sheet, a defect such as a defective press may occur.

[0004] Therefore, it is an object of the present invention to provide a material determination method capable of reducing the cost and time required for a test for quality assurance and ensuring the quality over the entire length of a steel sheet.

[0005]

In order to solve the above problems, in the first invention of the present application, a Young's modulus measuring device is installed in a steel sheet production line, and the Young's modulus measured by the Young's modulus measuring device is set. The area on the steel plate smaller than a predetermined value is tracked, and the area is cut and removed by a shear.

According to the second aspect of the invention, a Young's modulus measuring device is installed in the steel sheet manufacturing line, the rank fold value is estimated based on the Young's modulus actually measured by the Young's modulus measuring device, and the rank-forward value is obtained by the estimation. An area on the steel plate having a rank rank value smaller than a predetermined value is tracked, and the area is cut and removed by a shear.

[0007]

That is, in the present invention, by installing a Young's modulus measuring device in the steel sheet production line, the quality of the entire steel sheet (Young's modulus or rank-forward value) is detected online,
The portion in which poor quality is detected is cut off using a shear.
Therefore, the sampling work of the steel sheet is unnecessary, and the poor quality portion of the entire steel sheet can be cut off in one treatment to guarantee the quality of the remaining steel sheet. The cost of is also greatly reduced.

[0008]

EXAMPLE FIG. 1 schematically shows the structure of a steel sheet production line for carrying out the present invention. In the steel sheet production line of FIG. 1, the length meter PLG measures the coil length, and the Young's modulus measuring device 4 measures the Young's modulus of the steel sheet. Then, the respective information is taken into the computer 6, processed and tracked, and the shear 5 arranged on the front surface of the coil winder 2.
Is controlled to automatically cut the steel sheet at the cutting position tracked by the computer 6 to cut off the defective portion.

That is, in order to obtain deep drawability in a cold rolled steel sheet, it is necessary to obtain a {111} texture in which the {111} plane is parallel to the sheet surface. In order to obtain large and completely recrystallized crystal grains in a short time as in continuous annealing and to impart good formability and deep drawability, it is necessary to reduce the solid solution elements and precipitated particles that delay recrystallization as much as possible. However, in the inner and outer winding parts of the hot rolled coil, the cooling rate is fast because it is in contact with the outside air, the growth of crystal grains in the steel is not promoted, and it may grow as large grains even after cold rolling recrystallization. Can not. In addition, impurities such as carbides in the steel exist finely without being sufficiently aggregated or coarsened, and these impurities hinder the growth of {111} recrystallized nuclei, which adversely affects the deep drawability, that is, the Young's modulus and rank-field value. Exert.

Therefore, the front end portion and the rear end portion of the steel sheet, in which the deep drawability is deteriorated, are cut and removed by using a shear 5. FIG. 3 shows a specific example thereof.

The Young's modulus measuring device 4 measures the Young's modulus of the steel sheet on the line in real time and outputs the measurement result to the computer 6. The Young's modulus measuring device 4 measures the Young's modulus using an electromagnetic ultrasonic method developed in recent years. The measurement principle will be briefly described.

First, the ultrasonic waves propagating in the plate thickness direction of the steel sheet are thickness-resonated by electromagnetic ultrasonic waves, and the resonance frequency f thereof is measured. Then, the Young's modulus E is obtained as follows.

From the resonance condition of V = f / λ, since λ = 2d / n, the following equation is obtained.

V = 2ndf V: sound velocity (5903 m / s: vertical wave, 3230 m / s: transverse wave) λ: wavelength d: plate thickness f: 3 to 13 MHz The sound velocity V is obtained from the resonance frequency f, and the sound velocity ratio (resonance frequency The Young's modulus E is calculated from the ratio).

E = f (K ₁ , K ₂ , K ₃ , C ₁₁ , C ₁₂ , C ₄₄ ) K ₁ : fzy / fzz K ₂ : fzx / fzz K ₃ : T ₀ / T ₄₅ (constant) fzz, fzx, fzy: Resonance frequency T ₀ , T ₄₅ : Two-direction (0 degree, 45 degree) ultrasonic wave propagation time C ₁₁ , C ₁₂ , C ₄₄ : Elastic coefficient of iron single crystal f = 6 / d → f: 7.5 MHz , D: 0.8 mm Incidentally, the rank rate value (plastic property of the steel sheet) Rf is correlated with the Young's modulus (elastic property of the steel sheet) E, and both depend on the crystal orientation.
The estimated value Rf can be estimated.

The computer 6 shown in FIG.
The Young's modulus of the steel sheet is taken in from the Young's modulus measuring device 4, and P
The length (moving distance) of the steel plate is taken in from LG (length meter) 3. Further, the computer 6 also takes in the type and thickness of the material of the steel sheet flowing through the production line.

The operation of the computer 6 will be described with reference to FIG. The captured Young's modulus E is the threshold value Eo.
Compared to. When the Young's modulus E changes as shown in FIG. 3, the computer 6 tracks the coil lengths L ₁ and L ₂ in the portions where the Young's modulus E does not exceed the threshold value Eo, and these portions are manufactured into steel plates. Cut automatically with the shear 5 on the rear side of the line. That is, when the boundary between the portion of E <Eo and the portion of E ≧ Eo is detected, it is detected that each boundary position on the steel plate reaches the shear 5 based on the count value of the PLG output pulse number. At times, the shear 5 is driven to cut the steel plate at each position. The threshold value Eo is automatically set according to the plate thickness and material of the steel plate to be passed.

Next, another embodiment will be described. In this example, the configuration of the device used is the same as in FIG.
The operation of the computer 6 is slightly different from that of the above embodiment. That is, the computer of this embodiment operates as shown in FIG. That is, the rank feed value R at each position on the steel plate
When f is detected, the detected rank-order value Rf is compared with a threshold value Rfo, and when a boundary between the part where Rf <Rfo and the part where Rf ≧ Rfo is detected, the PLG output pulse count is calculated based on the count value. Then, when it is detected that each boundary position on the steel plate reaches the shear 5, the shear 5 is driven to cut the steel plate at each position. The threshold value Rfo is automatically set according to the plate thickness and material of the steel plate to be passed.

The rank rate value Rf to be detected is calculated by the computer 6 based on the Young's modulus measured by the Young's modulus measuring device 4. That is, there is a correlation, for example, as shown in FIG. 4, between the Young's modulus and the rank value Rf, and this correlation changes depending on the plate thickness and the material of the steel plate and is expressed by the following equation.

Rf = f (E, t, material) E: Young's modulus t: plate thickness Therefore, the computer 6 determines a regression formula for calculating the Rf value from the Young's modulus for each plate thickness and material, The regression formula determined was used to calculate the rank form from the measured Young's modulus E.
The calculated value Rf is obtained.

When the rank-field value Rf of a certain steel plate changes as shown in FIG. 6, the coil lengths L ₁ and L ₂ of the portion which does not exceed the threshold value Rfo are tracked, and this portion is tracked. Automatically cut at the shear 5 on the rear surface of the steel plate production line.

[0022]

As described above, according to the first aspect of the present invention, a non-contact type Young's modulus measuring device is provided in the steel sheet production line, and a portion with a measured Young's modulus is automatically detected on the production line. Cutting and removing eliminates the need for sampling and off-line mechanical testing for testing, significantly reducing testing costs and time for testing. Moreover, since the Young's modulus of the entire steel sheet is measured instead of the sampling test, the quality of the entire steel sheet can be guaranteed. In addition, unlike the case of sampling, it is not necessary to cut out a part that is not defective, so that the yield of steel sheets is improved.

According to the second aspect of the invention, the non-contact Young's modulus measuring device is provided in the steel sheet production line, the rank-fed value Rf is estimated from the Young's modulus measured on the production line, and the estimated Rf is calculated. Automatically cutting off defective values eliminates the need for sampling and off-line mechanical testing for testing, significantly reducing testing costs and time for testing. Moreover, since the Young's modulus of the entire steel sheet is measured instead of the sampling test, the quality of the entire steel sheet can be guaranteed. Further, unlike the case of sampling, it is not necessary to cut out even a non-defective portion, so that the yield of steel sheet is improved.

The Young's modulus E and the rank-forward value Rf are correlated with each other, and if one mechanical quality is guaranteed, the other mechanical quality can also be guaranteed. Therefore, in reality, the first invention and the first invention. Only one of the second aspect of the invention need be implemented.
The time required for computer calculation is shorter in the first invention. It should be noted that, when obtaining the rank rate value from the Young's modulus, an accurate rank rate is obtained by using an empirical formula (regression formula) obtained from the values actually measured for each material and plate thickness, as in the above-mentioned Examples. You can get the value

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of an apparatus for carrying out the present invention.

2 is a flowchart showing the operation of the computer 6 of FIG.

FIG. 3 is a graph showing positions on a steel plate, mechanical characteristics, and cutting positions.

FIG. 4 is a graph showing an example of the correlation between Young's modulus and rank fare value.

FIG. 5 is a flowchart showing the processing of a modified example.

FIG. 6 is a graph showing positions on a steel plate, mechanical characteristics, and cutting positions.

[Explanation of symbols]

1: POR (coil paying machine) 2: TR (coil winding machine) 3: PLG (length meter) 4: Young's modulus measuring device 5: shear 6: computer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Nawada Takashi Kimitsu 1 Kimitsu City Nippon Steel Corporation Kimitsu Works

Claims (2)

[Claims] 1. A Young's modulus measuring device is installed in a steel plate production line, and a region on the steel plate whose Young's modulus measured by the Young's modulus measuring device is smaller than a predetermined value is tracked and the region is cut and removed with a shear. A method for determining material quality in a steel sheet production line, comprising: 2. A Young's modulus measuring device is installed on a steel sheet production line, and a rank mode value is estimated based on the Young's modulus actually measured by the Young's modulus measuring system, and the rank mode value obtained by the estimation is A material determination method in a steel sheet production line, characterized by tracking an area on a steel sheet smaller than a predetermined value and cutting and removing the area with a shear.