JPH0381605A - Flatness measuring method - Google Patents

Abstract

PURPOSE:To measure the flatness of a beltlike body in travel motion with high accuracy by measuring the distances of respective parts of the metallic beltlike end surface of a metallic beltlike body in the width direction crossing its moving direction, separating a bus line variation quantity from the measured values by a frequency analysis, and removing the influence of tension. CONSTITUTION:Material thermometers 20 and 21 are arrayed on the inlet side and exit side for a cooling belt 14 in the plate width direction while facing the surface of a strip 1 which detects the breadthwise temperature distribution of the surface of the strip 1. The maximum temperature difference of the surface temperature distribution of the strip 1 is calculated from the detection results of the material thermometers 20 and 21 and outputted as a plate width-directional temperature difference to a shape converter 40. Further, distance detectors 30 and 31 are provided on the exit side of a continuous annealing furnace and an inspection base 4 on the exit side and distances to the strip surfaces are detected at respective parts in the plate width direction in a specific tension state and/or no-tension state. Detectors 30 and 31 have laser displacement gauges arrayed in the plate width direction, the respective laser displacement meters measure the distances to the surface of the strip 1 and output them as flatness to a computing element 70 and a storage device 50, and the computing element 70 outputs them to a shape converter 40.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the flatness of a strip such as a strip steel plate in a continuous annealing furnace.

[Prior art]

Generally, the steel plate is cooled in the cooling zone of a continuous annealing furnace by using a circulation fan to circulate the atmospheric gas in the furnace through a water-cooled gas cooler, and then spraying the cooled atmospheric gas onto the top and bottom sides of the steel plate. cooling is being done.

However, this method has a problem in that shape defects are likely to occur due to uneven cooling in the width direction of the steel plate due to the shape of the steel plate on the entrance side of the continuous annealing furnace. This is because if there is a shape defective portion such as a so-called edge extension where both ends of the steel plate are extended on the entrance side of the continuous annealing furnace, that portion is not cooled sufficiently and the shape defect is amplified by thermal stress.

In order to solve the above-mentioned problem, a distance detector is installed on the entrance or exit side of the cooling zone of the continuous annealing furnace to determine the distance (or height) to the surface of each part in the width direction of the plate, and based on this detector data, A method has been proposed in which the temperature in the width direction of the plate is controlled according to the determined shape in the width direction of the plate, that is, the flatness (Japanese Patent Laid-Open No. 61-2
No. 43130).

The flatness of a strip such as a steel plate during continuous annealing is determined by measuring the distance to the strip surface using multiple laser displacement meters placed in the width direction facing the surface of the strip, and then determining the flatness of the surface based on the measurement data. The amount of displacement is determined, and the steepness, h/1, is determined by the ratio of the displacement distance in the vertical direction of the cross section of the strip in the width direction and the width of displacement l in the width direction, as shown in FIG. It is designed to represent degree.

[Problem to be solved by the invention]

However, in the method for measuring flatness as described above, when detecting the amount of displacement of the surface of a strip during movement, it is difficult to calculate flatness while eliminating errors due to variations in the path line of the strip or errors due to changes in tension.

The present invention has been made in view of the above circumstances, and its purpose is to provide a flatness system that enables the flatness of a running metal strip to be measured without being affected by pass line fluctuations or tension fluctuations. To provide a measurement method.

[Means to solve the problem]

The flatness measuring method according to the present invention measures the distance of each part of the metal strip end surface in the width direction intersecting the moving direction of the metal strip, and separates the amount of pass line variation from this measurement value by frequency analysis. , further remove the influence of tension to calculate flatness.

[Effect]

According to the present invention, it is thereby possible to obtain highly accurate flatness that eliminates the influence of pass line fluctuations and furthermore the influence of tension.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 is a schematic diagram showing the case where the present invention is applied to the flatness measurement of a strip during annealing in a continuous annealing furnace, and in the figure, 1 indicates a strip of a metal strip such as an electrical steel sheet. Strip 1 is unwound from payoff reel 2,
Continuous annealing furnace 10. It passes through a looper 3 and an exit inspection table 4, is transported in the direction of the white arrow, and is wound onto a tension reel 5.

The continuous annealing furnace 10 includes a non-oxidizing furnace 11, a heating zone 12, a soaking zone 13, and a cooling zone 14, which are arranged in this order from the upstream side of the line for transferring the strip 1.

The non-oxidizing furnace 11 is configured to heat the strip 1 from both the front and back surfaces using direct fire burners, thereby removing rolling oil adhering to the surface of the strip 1 by burning it.

The heating zone 12 is configured to heat the strip 1 from both the front and back surfaces using a radiant tube in a reducing gas atmosphere, thereby reducing the thin oxide film on the surface of the strip 1 generated in the non-oxidation furnace 11.

The soaking zone 13 is for soaking electrical steel sheets and the like to sufficiently increase the crystal grain size, thereby improving the magnetic properties.

The cooling zone 14 is configured to circulate a reducing gas atmosphere through a water-cooled gas cooler using a circulation fan, and spray the cooled atmosphere onto the upper and lower surfaces of the strip 1 to cool it. Note that each cooling air volume is adjusted by adjusting the opening degree of a damper provided in each air supply path.

On the entrance and exit sides of the cooling zone 14, material temperature needles 20 and 21 are arranged in rows in the width direction of the strip 1, facing the surface of the strip 1 in order to detect the temperature distribution on the surface in the width direction of the strip 1, respectively. . As the material temperature needle 20.21, a scanning radiation thermometer (
Utility Model Application Publication No. 1r4-64031) etc. are used.

The maximum temperature difference in the surface temperature distribution of the strip 1 is calculated from the detection results by the material temperature needles 20 and 21, and this is output to the shape converter 40 as a temperature difference in the width direction of the strip.

In addition, distance detectors 30 and 31 are installed on the continuous annealing furnace exit side and the continuous annealing furnace exit side inspection table 4, and the distance detectors 30 and 31 are installed on the strip surface at each part in the width direction of the strip under a predetermined tension state and/or under no tension state. It is designed to detect the distance. Each of these detectors 30 and 31 is a plurality of laser displacement meters arranged in the board width direction, and each laser displacement meter measures the distance to the surface of the striker 9 and the flatness calculator 70 and the flatness calculator 70. It is designed to be output to the storage device 50. Flatness calculator 70
Ha, each distance! Based on the detection data from the lil detectors 30 and 31, in the next process, the flatness is calculated by removing the effects of path line fluctuations and tension, and this is output to the shape converter 40.

Figure 2 shows the measured values of the shape detector 30 in the width direction of the strip at each part in the longitudinal direction of the strip on the outlet side of the annealing furnace. It is shown by taking the height of In FIG. 2, the large peaks that appear are steepness, and the small irregularities that appear within these large peaks are waveforms caused by path line fluctuations. Therefore, by regarding this measured value data as a function and decomposing it into a Fourier series, a count for each term, that is, a power spectrum distribution diagram as shown in FIG. 3 for each wavelength can be obtained. FIG. 3 is a power spectrum distribution diagram, in which the horizontal axis represents the wavelength (fl) and the vertical axis represents the power spectrum.

In this distribution map, it is thought that the reason why both the wavelength and the power spectrum value are small is due to the path line fluctuation, and the reason why the wavelength and the power spectrum value are large is due to the steepness. Therefore, if we look at the correlation between the measured value of the distance detector 30 under a tension-free condition as shown in FIG. 4 and the term of the maximum value of the power spectrum shown in FIG. 3, the correlation will be as shown in FIG. 5. In Figure 5, the horizontal axis shows the value of the term indicating the maximum value of the power spectrum, and the vertical axis shows the peak height h under no tension.
This is an indication. As is clear from this graph, there is a substantially linear relationship between the two.

Therefore, the power spectrum distribution as shown in FIG. 3 is obtained for the measured value data as shown in FIG. This means that it is possible to obtain the mountain height h from which the influence of is removed.

The shape converter 40 converts the temperature difference in the strip width direction inputted from the material thermometer 20.21 based on the correlation between the temperature difference in the strip width direction and the steepness, which is predetermined based on past actual operation data. Convert the steepness to the 1a calculation result and store it in the storage device 50.
and output to the automatic control device 60.

The comparison calculator 70 compares the steepness signal inputted from the storage device 50 and the steepness signal input manually from the widthwise shape detector 30.31, and provides the steepness signal to the shape converter 40 based on the comparison result. A signal for correcting the correlation between the material temperature and steepness is output to the shape converter 40. Based on the steepness signal input from the shape converter 40, the automatic control device 60 calculates, for example, that if the detected shape in the width direction of the strip 1 is in a state in which the central portion is swollen, the temperature of the central portion is higher than that of other portions. A control signal is output to the damper drive device 80 to reduce the opening degree of the damper that adjusts the amount of cooling air at the center in the board width direction so that the temperature becomes higher than the temperature. The damper drive device 80 adjusts the opening degree of the damper according to a control signal manually input from the automatic control device 60, thereby adjusting the cooling landscape.

〔effect〕

As described above, in the method of the present invention, the distance to the surface of the strip is measured using a distance meter, and from this measurement value, the amount of pass line variation and furthermore, the highly accurate flatness is calculated by removing the influence of tension. The present invention has excellent effects, such as being able to manage the flatness with even more precision.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the case where the method of the present invention is applied to a strip being annealed in a continuous annealing furnace, Fig. 2 is a graph showing the measured value of the distance meter on the outlet side of the annealing furnace, and Fig. 3 is a power spectrum distribution diagram. Fig. 4 is a graph showing the rangefinder measurement value under no tension, Fig. 5 is a graph showing the relationship between the maximum value of the power spectrum and the mountain height h, and Fig. 6 is an explanatory diagram of flatness. be. 1...Strip 2...Leiofurir 10
... Continuous annealing furnace 20.21 ... Material temperature gauge 30
．． 31... Board width direction shape detector

Claims (1)

[Claims] 1. Measure the distance to the surface of the metal strip at multiple points in the width direction intersecting the moving direction of the metal strip, and separate and remove the amount of pass line variation from the measured values by frequency analysis. A flatness measurement method characterized by calculating flatness after calculating the flatness. 2. The method for measuring flatness according to claim 1, wherein the calculated flatness is calibrated to the flatness under no tension.