JPH05332710A - Method and device of measuring flatness of thick steel plate - Google Patents

Abstract

PURPOSE:To accurately measure the flatness of a thick steel plate by varying the cutoff frequency of a low-pass filter inserted into a distance signal passage for a distance meter in proportion to the carry speed of the thick steel plate. CONSTITUTION:For pulses generated by a pulse generator 4 directly connected to a carrying roll 2, a pulse rate is found by repeatingly calculating due number of short-time pulses and dividing it by a time. A carry speed computer 9 finds the carry speed from the pulse rate and determines the set voltage of a voltage synchronized low-pass filter 11 so as to induce a cutoff frequency proportional to the speed. In this way, the value of time cutoff frequency of the low-pass filter 11 is proportional to the carry speed, so that the cutoff frequency of the low-pass filter in a signal passage for a non-contact distance meter 3 can be lowered as much as possible, a distortional waveform from which the vibration components of a thick steel plate is only removed can be accurately measured and a distortion computed value can be thus accurately found.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the flatness of a thick steel plate, and always accurately measures the flatness of a thick steel plate used in a process such as a running inspection in a thick steel plate manufacturing process in which the transport speed changes. I will try to let you do it.

[0002]

2. Description of the Related Art In the manufacturing process of thick steel plates, they are conveyed at a relatively low speed of 30 to 45 mpm for visual inspection from the upper and lower surfaces of the thick steel plates, and immediately before or immediately after that, at a relatively high speed of about 90 mpm, they are conveyed. Be transported. On the other hand, in the case of such a method, since the flatness meter is installed on the lower surface than the pass line, it is necessary to install the flatness meter in front of or behind the running inspection room to some extent so as not to interfere with the visual inspection of the lower surface. is there. Therefore, when the steel plate is installed in front of the running distance inspection room, the transport speed is about 90 mp when the thick steel plate enters the position where the non-contact distance meter, which is the flatness meter, is installed.
m, and the deceleration starts immediately after that, and most of the thick steel plate slightly beyond the leading end has a conveying speed of 30 to 45 mpm.

According to the results of various studies by the present inventors,
The vibration frequency during transportation is 7 Hz for normal thick steel plates
From the above, it was confirmed that it did not depend on the transport speed. Further, since the frequency of the steel sheet distortion itself is 6 Hz or less even at the maximum conveying speed of 90 mpm, in the Japanese Patent Application No. 02-162719, which is the prior application of the applicant, the vibration component has a cutoff frequency of 7
It is removed by a steep low-pass filter of Hz.

[0004]

The above-mentioned conventional techniques still have various problems even if they are preferable as such. That is, in the steel sheet to be conveyed, when the pitch of the crests is large as shown in FIG. 3 described later or when the warped portion is long as shown in FIG. 5, the vibration frequency during conveyance is lower than 7 Hz and the cutoff frequency is 7 Hz. The distortion waveform that cannot be removed by the filter is an observed distortion waveform in which the vibration waveform is superimposed on the original distortion waveform as shown in FIGS. 4A and 6A. Further, in such a flatness meter, various distortion calculations are performed as shown in FIG. 7, but 2 m distortion of steepness (e) in FIG. 7C,
There is a particular adverse effect on the calculation of the 1 m distortion in (f).

[0005]

As a result of repeated studies to solve the above-mentioned technical problems of the present invention, in the thick steel plate flatness meter as described above, the distance signal path is An effective solution has been obtained by appropriately controlling the cutoff frequency in the low-pass filter to be inserted, and is as follows.

(1) A plurality of non-contact distance meters are vertically installed on the lower surface between two rolls of a transport table, and the steel sheet is moved over the transport table of the thick steel sheet by the distance gauge over the entire surface of the thick steel sheet. The distance change between the pass line and the back surface of the thick steel plate, that is, the strain waveform, obtained by measuring the distance to the back of the In a steel plate flatness meter for performing distortion calculation using, a steel plate characterized by varying a cutoff frequency in a pass filter inserted in a distance signal path of the non-contact distance meter in proportion to a transport speed of the steel plate. Flatness measurement method.

(2) A plurality of non-contact distance meters are installed vertically on the lower surface between the two rolls of the transport table, and while the thick steel plate is being moved on the transport table, the thickness of the non-contact distance meter is measured by the distance meter over the entire surface of the thick steel plate. The distance to the back surface of the steel sheet was measured at each constant distance pitch in the longitudinal direction, and the distance change between the paraffin and the thick steel sheet back surface obtained by subtracting the distance between the distance meter and the pass line, which was obtained in advance, that is, strain In a steel plate flatness meter that performs distortion calculation using a waveform, a cut-off frequency that is variable in proportion to the transport speed of the steel plate is introduced into the low-pass filter inserted in the distance signal path of the non-contact distance meter. An apparatus for measuring the flatness of a thick steel plate, which eliminates an adverse effect on the distortion waveform due to the vibration of the.

[0008]

[Function] Among the distortions of the thick steel plate, the wavy ones with a small pitch are called small waves. Thick steel plates with small waves are basically impossible to inspect, but the pitch of the small waves is 250-3
It is known to be 00 mm. Therefore, the conveying speed of the thick steel plate is detected and calculated by the pulse generator directly connected to the conveying roll, and the maximum value of the distortion frequency of the thick steel plate to be passed is 25
Strain of thick steel plate can be collected without omission by automatically adjusting the cutoff frequency of the low-pass filter inserted in the signal path of each non-contact distance meter to match the above frequency, which is obtained in accordance with the 0 mm pitch small wave. However, it is possible to eliminate the vibration component caused by unnecessary conveyance.

To explain this more specifically, the operation when a low-pass filter of the frequency variable system is inserted in the signal path of the non-contact distance meter which constitutes the flatness meter as described above will be described with reference to FIGS. 7, the thick steel plate to be conveyed is shown in FIG.
As shown in Fig. 5, when the warp is long, the vibration frequency during conveyance is lower than 7 Hz and cannot be removed by a low-pass filter with a cut-off frequency of 7 Hz. Is shown in FIG. 4 (a) and FIG. 6 (a).
As described above, a vibration waveform is superimposed on the original distortion waveform. This is pitch 250 at high speed 90 mpm
This is an unavoidable problem as long as a low-pass filter with a fixed cutoff frequency can be used because it is possible to collect small wave components of mm.

However, as shown in FIG. 1, the pulse rate of the pulse generated by the PLG directly connected to the transport roll is calculated, the transport speed is obtained from the pulse rate, and the voltage tuning low-pass is set so that the cutoff frequency is proportional to the transport speed. Determine the set voltage of the filter. As a result, as shown in FIG. 7, the cutoff frequency of the low-pass filter becomes a value proportional to the transport speed, and the strain pitch of the steel sheet that can be sampled is 2
The cutoff frequency of the low-pass filter in the signal path of the non-contact distance meter can be lowered as much as possible while keeping the distance to 50 mm or more.
Fig. 4 shows the running inspection process carried at a low speed of mpm.
As shown in (b) and (b) of FIG. 6, only the vibration component of the steel sheet is effectively removed and the strain waveform is accurately measured. As a result, the strain calculation value is accurately obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Explaining a specific embodiment of the present invention as described above, the pulse rate of the pulse generated by the pulse generator 4 directly connected to the transport roll 2 as shown in FIG. 1 is calculated. Roll radius is r (m
m), the roll circumference is 2 x π x r (mm), the number of pulses per revolution of the pulse generator is N (ppr), the transport speed is V (mpm),
If the pulse rate is PR (p / sec), the transport speed V
The pulse rate PR at (mpm) is PR = V × 1000/60 ÷ (2 × π × r) × N p /
sec, which is proportional to the transport speed V. In practice, the pulse rate calculator 8 can calculate the pulse rate by repeatedly calculating the number of pulses in a short time (for example, 0.5 sec) and dividing the number by the time.

The transport speed calculator 9 obtains the transport speed V from the above-mentioned pulse rate by the following equation. V = 60 × 2 × π × r × PR / (1000 × N) mpm Further, the set voltage of the voltage tuning low-pass filter 11 is determined so that the cutoff frequency is proportional to the carrier speed V. The cutoff frequency fc to be set is fc = V × 1000 / (60 × 250) Hz. When the set voltage is SV when the cutoff frequency fc of the voltage tuning low-pass filter 11 is proportional to the set voltage, fc = kl × SV Hz. Here, kl is a proportional constant. In the set voltage calculator 10, the set voltage SV is obtained as SV = V / (15 × kl).

As a result, as shown in Table 1 below, the cut-off frequency fc of the low-pass filter becomes a value proportional to the conveying speed, and the strain pitch of the thick steel plate 1 that can be sampled is set to 250.
The cut-off frequency fc of the low-pass filter in the signal path of the non-contact distance meter 3 can be lowered as much as possible while keeping the value at least mm, and only the tip portion is high speed and most of the rest is 30 to 4
Fig. 4 shows the running inspection process carried at a low speed of 5 mpm.
(B), as shown in FIG. 6 (b), only the vibration component 24 or 27 of the thick steel plate 1 is effectively removed, and the strain waveform is accurately measured.
As a result, the distortion calculation value is accurately obtained.

[0014]

[Table 1]

It goes without saying that the present invention can be applied to hot-rolled steel sheets having a high or low conveying speed.
As shown in Table 2 below, the cutoff frequency fc of the low pass filter has a value proportional to the transport speed. Here, the transport speed is 15 to 120 mpm, the minimum strain pitch in question is 700 mm, and the cutoff frequency fc of the steel plate vibration elimination low-pass filter is fc = V × 1000/60 × 700 Hz = 0.024.
× V Hz.

[0016]

[Table 2]

[0017]

According to the present invention as described above,
The low-pass filter inserted in the signal path of the non-contact distance meter has a variable cut-off frequency, and the cut-off frequency is set to a value proportional to the carrier speed, so only the vibration component of thick steel plate is effectively removed. The distortion waveform is accurately measured, and as a result, the distortion calculation value can be accurately determined, which is an invention having a great effect industrially.

[Brief description of drawings]

FIG. 1 is a configuration explanatory diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a conventional technique.

FIG. 3 is an explanatory view showing a relationship between a carrier roll and a mountain pitch of thick steel plates in the present invention.

FIG. 4 is an explanatory diagram of a relationship between a pass line and a distortion waveform.

FIG. 5 is an explanatory diagram showing a relationship between a transport roll pass line and a height of a thick steel plate warp portion.

FIG. 6 is an explanatory diagram of a warp portion for a pass line and a distortion waveform.

FIG. 7 is an explanatory diagram of various distortion calculations in the flatness meter.

[Explanation of symbols]

 1 Thick Steel Plate 2 Transport Roll 3 Non-contact Distance Meter 4 Pulse Generator 5 Roller 6 Passage Detector 7 Pulse Counter 8 Pulse Slate Calculator 9 Transport Speed Calculator 10 Set Voltage Calculator 11 Voltage Tuning Low Pass Filter 12 Insulation Pre-Amplifier 13 First Calculation Device 14 Second calculator 15 Controller 16 Low-pass filter 17 Calculation unit 18 Printer 19 Terminal 20 Terminal 21 Output unit 22 Path line 23 Pitch of mountain 24 Distorted waveform 25 Distorted waveform 26 Length of sled part 27 Distorted waveform 28 Distorted waveform

Claims (2)

[Claims] 1. A plurality of non-contact distance meters are vertically installed on a lower surface between two rolls of a transport table, and the steel sheet is moved by the distance meter over the entire surface of the steel sheet while moving the steel sheet on the transport table. The distance to the back surface of the paraffin and the back surface of the thick steel plate obtained by subtracting the distance between the distance meter and the pass line, which was obtained in advance, by measuring the distance in the longitudinal direction at constant pitches, that is, the distortion waveform In a steel plate flatness meter for performing distortion calculation using, the cutoff frequency in the low-pass filter inserted in the distance signal path of the non-contact distance meter is variable in proportion to the transport speed of the steel plate. Steel plate flatness measurement method. 2. A plurality of non-contact distance meters are vertically installed on a lower surface between two rolls of a transport table, and the steel sheet is moved over the transport table while the steel sheet is moved over the entire surface of the steel sheet by the distance gauge. The distance to the back surface of the paraffin and the thick steel plate back surface obtained by subtracting the distance between the distance meter and the pass line, which was obtained in advance, by measuring the distance in the longitudinal direction at constant pitches, that is, the strain waveform In a steel plate flatness meter that performs distortion calculation using, a cutoff frequency that is variable in proportion to the transport speed of the steel plate is introduced to the low-pass filter inserted in the distance signal path of the non-contact distance meter, An apparatus for measuring the flatness of a thick steel plate, which is characterized by eliminating the adverse effect of vibration on a distorted waveform.