JP2004138533A - Apparatus and method for measuring length of steel member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the length of a steel plate with high precision by simple means, while conveying the steel plate. <P>SOLUTION: A conveyance speed V of a steel member is measured by a laser Doppler velocimeter, and along with detecting the tip of the steel member using a front range finder, the distance H<SB>F</SB>between the front range finder and the steel member is measured. Along with detecting the rear end of the steel member using a back range finder, the distance H<SB>B</SB>between the back range finder and the steel member is measured. On the basis of the distances H<SB>F</SB>and H<SB>B</SB>, the conveyance speed V is corrected. The length L of the steel member is computed from formula (1), using time of detection t<SB>1</SB>of the tip by the front range finder, time of detection t<SB>2</SB>of the rear end by the back range finder, the corrected value V<SB>R</SB>of the conveyance speed, and the distance D between the front and back range finders. <P>COPYRIGHT: (C)2004,JPO

Description

【００１３】
Ｌ　：鋼材の長さ（ｍ）
Ｄ　：前部距離計と後部距離計との間隔（ｍ）
Ｖ_Ｒ：搬送速度の補正値（ｍ／ｓｅｃ　）
ｔ_１：前部距離計が鋼材の先端を検出した時刻
ｔ_２：後部距離計が鋼材の後端を検出した時刻
前記した長さ測定方法の発明においては、前部距離計が鋼材の先端を検出したときにレーザドップラ速度計による搬送速度の測定を開始し、後部距離計が鋼材の後端を検出したときにレーザドップラ速度計による搬送速度の測定を停止することが好ましい。
【００１４】
【発明の実施の形態】
図１は、本発明の長さ測定装置の例を模式的に示す側面図である。図１中の矢印ａは鋼材１の搬送方向を示す。
本発明では、図１に示すように、鋼材１をローラコンベア（図示せず）等で搬送しながら、レーザドップラ速度計２を用いて鋼材１の搬送速度Ｖ（ｍ／ｓｅｃ　）を測定する。レーザドップラ速度計２は、図２に示すように、２個のレーザ発光器６ａ，６ｂと１個のレーザ受光器７が配設される。
【００１５】
レーザドップラ速度計２を用いて鋼材１の搬送速度Ｖ（ｍ／ｓｅｃ　）を高精度で測定するためには、図２に示すように、レーザ発光器６ａ，６ｂから照射されたレーザ照射光５ａ，５ｂが交差する範囲Ｍを、鋼材１が通過する必要がある。特にレーザ照射光５ａ，５ｂが交差する範囲Ｍの中心を鋼材１の上面が通過するように設定すると、搬送速度Ｖの測定精度が向上する。
【００１６】
このようにして鋼材１の搬送速度Ｖ（ｍ／ｓｅｃ　）を高精度で測定するためには、レーザドップラ速度計２と鋼材１との距離Ｈの変動を抑制するとともに、鋼材１の搬送方向に対して直角な方向から搬送速度Ｖを測定する必要がある。ここで鋼材１の搬送方向に対して直角な方向から測定するとは、レーザ受光器７が鋼材１の搬送方向に対して直角な方向に配設され、鋼材１から垂直に反射されたレーザ反射光８を受光することを指す。
【００１７】
なお、図１には鋼材１の上面に垂直な方向（すなわち鋼材１の搬送方向に対して直角な方向）から搬送速度Ｖを測定する例を示す。ただし本発明においては、鋼材１の側面に垂直な方向（すなわち鋼材１の搬送方向に対して直角な方向）から搬送速度を測定することも可能である。
鋼材１の製造工程では、通常、ローラコンベアを用いて鋼材１を搬送する。このとき、図１に示すように鋼材１の上面に垂直な方向から搬送速度Ｖを測定する場合には、鋼材１の上面が波状になっているとレーザドップラ速度計２と鋼材１との距離Ｈが変動する。
【００１８】
あるいは鋼材１の側面に垂直な方向から搬送速度を測定する場合には、ローラコンベア上の鋼材１が位置を変位すると、レーザドップラ速度計２と鋼材１との距離Ｈが変動する。
このようにしてレーザドップラ速度計２と鋼材１との距離Ｈが変動すると、搬送速度Ｖを測定する角度も変化し、搬送速度Ｖの測定精度が低下する。
【００１９】
そこで図１に示すように、レーザドップラ速度計２の下流側に前部距離計３を配設して、搬送される鋼材１の先端を検出するとともに、前部距離計３と鋼材１との距離Ｈ_Ｆ（ｍｍ）を測定する。さらにレーザドップラ速度計２の上流側に後部距離計４を配設して、後部距離計４と鋼材１との距離Ｈ_Ｂ（ｍｍ）を測定するとともに、搬送される鋼材１の後端を検出する。
【００２０】
なお本発明では、搬送速度Ｖ，距離Ｈ_Ｆ，距離Ｈ_Ｂを連続測定する。
このようにして前部距離計３で測定した距離Ｈ_Ｆと後部距離計４で測定した距離Ｈ_Ｂに基づいて、搬送速度の測定値Ｖ（ｍ／ｓｅｃ　）を補正する。その搬送速度の測定値Ｖの補正方法の一例を図３に示す。すなわち図３は、図２中の範囲Ｍの中心に対する平均距離Ｈ_ＡＶＥ（ｍｍ）の変位と搬送速度の測定誤差（％）との関係を示すグラフであり、この図３から搬送速度の測定誤差（％）を読み取って搬送速度の測定値Ｖ（ｍ／ｓｅｃ　）を補正し、搬送速度の補正値Ｖ_Ｒ（ｍ／ｓｅｃ　）を求める。なお平均距離Ｈ_ＡＶＥ（ｍｍ）は、距離Ｈ_Ｆ（ｍｍ）と距離Ｈ_Ｂ（ｍｍ）の平均値である。
【００２１】
一方、レーザドップラ速度計２の下流側に配設される前部距離計３は、搬送される鋼材１の先端を検出する。その状態を図４に示す。前部距離計３と後部距離計４との間隔をＤ（ｍ），鋼材１の長さをＬ（ｍ）とすると、後部距離計４と鋼材１後端との距離Ｉ（ｍ）は、下記の　（２）式で表わされる。
Ｉ＝Ｌ−Ｄ　　　　　　　　　　　　　　　　　・・・　（２）
Ｌ：鋼材の長さ（ｍ）
Ｄ：前部距離計と後部距離計との間隔（ｍ）
Ｉ：前部距離計が鋼材の先端を検出したときの後部距離計と鋼材後端との距離（ｍ）
さらに鋼材１が矢印ａの方向へ搬送されて、後部距離計４が鋼材１の後端を検出した状態を図５に示す。このとき、鋼材１先端と前部距離計３との距離は、上記した距離Ｉに等しく、　（２）式で表わされる。
【００２２】
この距離Ｉは、前部距離計３が鋼材１先端を検出してから後部距離計４が鋼材１後端を検出するまでの間に鋼材１が搬送される距離に等しい。したがって距離Ｉは、前部距離計３が鋼材１先端を検出した時刻ｔ_１，後部距離計４が鋼材１後端を検出した時刻ｔ_２，搬送速度の補正値Ｖ_Ｒ（ｍ／ｓｅｃ　）から下記の　（３）式で算出される。
【００２３】
【数３】

【００２４】
Ｉ　：前部距離計が鋼材の先端を検出したときの後部距離計と鋼材後端との距離（ｍ）
Ｖ_Ｒ：搬送速度の補正値（ｍ／ｓｅｃ　）
この　（３）式を　（２）式に代入すると　（１）式が得られる。
【００２５】
【数４】

【００２６】
この　（１）式において、前部距離計３と後部距離計４との間隔Ｄは、一定に固定されるので誤差は生じない。誤差が生じる可能性があるのは搬送速度の補正値Ｖ_Ｒであるが、上記で説明したように、その精度は前部距離計３と後部距離計４の測定値を用いることで大幅に改善されている。
このようにして本発明では、鋼材１を搬送しながら高精度で長さを測定でき、搬送される鋼材１がローラコンベア上で位置を変位しても、高精度を維持できる。しかも前部距離計３と後部距離計４が、それぞれ鋼材１の先端と後端を検出し、かつ鋼材１との距離Ｈ_Ｆ，Ｈ_Ｂを測定するので、鋼材１先端の検出装置，鋼材１後端の検出装置，距離Ｈ_Ｆの測定装置，距離Ｈ_Ｂの測定装置を個別に設置する必要はない。したがって簡便な装置で鋼材１の長さを測定できる。
【００２７】
なお本発明では、レーザドップラ速度計２で鋼材１の搬送速度を常時測定しても良いし、あるいは前部距離計３が鋼材１先端を検出してから後部距離計４が鋼材１後端を検出するまでの間のみ鋼材１の搬送速度を測定しても良い。いずれの場合も、同様の測定精度が得られる。
【００２８】
【実施例】
ローラコンベアを用いて鋼材１を搬送しながら、図１の装置を用いて本発明を適用して鋼材１の長さＬ（ｍ）を求めた。鋼材１の長さＬは　（１）式で求められる値である。
【００２９】
【数５】

【００３０】
次いで鋼材１の長さを巻尺で実測し、実測値Ｌ_Ｍ（ｍ）を求めた。こうして求めた鋼材１の長さＬと実測値Ｌ_Ｍを用いて、下記の　（４）式から指標αを算出して誤差を評価した。これを発明例とする。なお、指標αが０％に近いほど誤差が小さい。
α（％）＝１００　×（Ｌ_Ｍ−Ｌ）／Ｌ_Ｍ　　　　　・・・　（４）
一方、比較例として、後部距離計４による鋼材１との距離の検出を停止して後端検出のみを行ない、前部距離計３で鋼材１の先端検出および距離測定を行なった。以上の測定値から鋼材１の搬送速度を補正してＶ_Ｒ’として、下記の　（５）式で鋼材１の長さＬ’（ｍ）を求めた。
【００３１】
【数６】

【００３２】
次いで鋼材１の長さを巻尺で実測し、実測値Ｌ_Ｍ（ｍ）を求めた。こうして求めた鋼材１の長さＬ’と実測値Ｌ_Ｍを用いて、下記の　（６）式から指標βを算出して誤差を評価した。なお、指標βが０％に近いほど誤差が小さい。
β（％）＝１００　×（Ｌ_Ｍ−Ｌ’）／Ｌ_Ｍ　　　　・・・　（６）
発明例と比較例について、各々５０本の鋼材１の長さＬ，Ｌ’を測定し、指標α，βを求めた。その結果、比較例では指標βが０．１３〜０．２１％であったのに対して、発明例では指標αが０．０２〜０．０３％であった。したがって本発明によって、鋼材１を搬送しながら、その長さを高精度で測定できることが確かめられた。
【００３３】
【発明の効果】
本発明によれば、鋼板を搬送しながらその長さを測定するにあたって、簡便な手段で、しかも高精度で長さを測定できる。
【図面の簡単な説明】
【図１】本発明の長さ測定装置の例を模式的に示す側面図である。
【図２】レーザドップラ速度計の例を模式的に示す側面図である。
【図３】距離の変位と搬送速度の測定誤差との関係を示すグラフである。
【図４】前部距離計が鋼材の先端を検出した状態を示す側面図である。
【図５】後部距離計が鋼材の後端を検出した状態を示す側面図である。
【符号の説明】
１　鋼材
２　レーザドップラ速度計
３　前部距離計
４　後部距離計
５　レーザ照射光
５ａ　レーザ照射光
５ｂ　レーザ照射光
６ａ　レーザ発光器
６ｂ　レーザ発光器
７　レーザ受光器
８　レーザ反射光[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for measuring a length of a steel material while transporting the steel material at an entry side or the like of the cutting device for cutting the steel material to a predetermined length.
[0002]
[Prior art]
In the steel manufacturing process, the length of the steel is measured as necessary from the viewpoint of operation management or quality control in each process. In particular, on the entry side of a cutting device for cutting a steel material to a predetermined length, if the accuracy of length measurement is inferior, the yield is reduced. For these reasons, when measuring the length of a steel material in the steel manufacturing process, high-precision measurement is required.
[0003]
When measuring the length of a steel material, stopping the conveyance of the steel material and measuring the length of the stationary steel material enables highly accurate measurement. However, in this method, it is inevitable that the productivity is reduced by stopping the transfer of the steel material.
Therefore, various techniques for measuring the length while transporting the steel material have been studied. For example, a length measurement technique combining a touch roll that rotates in contact with a conveyed steel material and an encoder that measures the number of rotations of the touch roll is conventionally known. However, in such a contact-type length measuring technique, when the friction between the steel material surface and the touch roll is small, the touch roll does not rotate, and a large measurement error occurs. In addition, even when irregularities occur on the surface of the steel material, the rotation of the touch roll becomes unstable, and a measurement error occurs.
[0004]
In order to solve such a problem of the contact type length measuring technique, various non-contact type length measuring techniques have been proposed.
As a non-contact length measuring technique, a material length measuring apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-109807. This technology measures the speed of a steel sheet with a laser light interference type speedometer, and installs two steel plate passage detectors to detect the leading and trailing ends of the steel sheet, respectively. The length of the steel plate is calculated by calculating data measured by the passage detector. However, the technique disclosed in Japanese Patent Application Laid-Open No. 58-109807 discloses that when the position of a steel sheet changes on a roller conveyor and the distance between the laser light interference type speedometer and the steel sheet fluctuates, an error occurs in the measured value of the steel sheet speed. An error also occurs in the steel sheet length calculated using the steel sheet speed.
[0005]
Japanese Patent Application Laid-Open No. Sho 62-240805 discloses a length measuring instrument. This technology measures the speed of a steel plate with a laser Doppler velocimeter, detects the front and rear ends of the steel plate by installing two object detectors, and further measures with these laser Doppler velocimeter and an object detector. The length of the steel plate is calculated by calculating the data. However, in the technique disclosed in Japanese Patent Application Laid-Open No. Sho 62-240805, although the accuracy of length measurement is improved as compared with the technique using a laser light interferometer, the position of a steel sheet changes on a roller conveyor. When the distance between the laser Doppler velocimeter and the steel sheet fluctuates, an error occurs in the measured value of the steel sheet speed, and an error also occurs in the steel sheet length calculated using the steel sheet speed.
[0006]
Japanese Patent Laying-Open No. 62-127686 discloses a laser Doppler velocimeter. This technology uses a laser Doppler velocimeter to measure the speed of a moving object by installing one displacement meter, measuring the distance between the moving object and the displacement meter, and changing the laser Doppler velocity according to the change in the distance. The accuracy of measuring the speed of the moving object is improved by correcting the measurement value of the meter.
[0007]
When measuring the length of a moving object using the technique disclosed in Japanese Patent Application Laid-Open No. 62-127686, a moving object is detected in addition to the displacement meter disclosed in Japanese Patent Application Laid-Open No. 62-127686. Must be installed. Therefore, the configuration of the apparatus becomes complicated, which not only increases the cost of the apparatus but also increases the load of maintenance.
[0008]
[Patent Document 1]
JP-A-58-109807 [Patent Document 2]
JP-A-62-240805 [Patent Document 3]
Japanese Patent Application Laid-Open No. 62-127686
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems and to provide a measuring apparatus and a measuring method that enable high-precision measurement by simple means when measuring the length of a steel sheet while transporting the steel sheet. .
[0010]
[Means for Solving the Problems]
The present invention relates to a laser Doppler velocimeter for measuring a conveying speed of a steel material to be conveyed, and a front distance meter arranged downstream of the laser Doppler velocimeter for detecting a tip of the steel material and measuring a distance to the steel material. And a rear rangefinder that is located upstream of the laser Doppler velocimeter to measure the distance to the steel and detect the rear end of the steel, and a laser Doppler velocimeter, a front rangefinder, and a rear rangefinder And a computing device that performs computational processing using data as an input signal.
[0011]
Further, according to the present invention, the conveying speed V (m / sec) of the steel material is measured using a laser Doppler velocimeter, and the tip of the steel material is detected using a front distance meter disposed downstream of the laser Doppler velocimeter. steel with with measuring the distance H _F of the front distance meter and a steel, to measure the distance H _B of the rear distance meter and a steel material with a rear distance meter which is disposed upstream of the laser Doppler velocimeter to the rear end detects the distance H _F and distance to correct the conveying speed V (m / sec) based on H _B, the time t ₁ the front distance meter detects the leading _end, a rear distance meter a rear end detected time _{t 2, the} correction value _V R of the conveying speed (m / sec), the length of the steel material by using a distance D (m) between the front distance meter and a rear distance meter (1) below L ( This is a length measurement method for calculating m).
[0012]
(Equation 2)

[0013]
L: Length of steel material (m)
D: Distance between front distance meter and rear distance meter (m)
V _R: correction value of the transport speed (m / sec)
t ₁ : Time when the front distance meter detects the tip of the steel material t ₂ : Time when the rear distance meter detects the rear end of the steel material In the above-described invention of the length measuring method, the front distance meter measures the front end of the steel material. It is preferable that the measurement of the transport speed by the laser Doppler velocimeter is started when it is detected, and the measurement of the transport speed by the laser Doppler velocimeter is stopped when the rear distance meter detects the rear end of the steel material.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a side view schematically showing an example of the length measuring device of the present invention. The arrow a in FIG. 1 indicates the direction in which the steel material 1 is conveyed.
In the present invention, as shown in FIG. 1, while the steel material 1 is being conveyed by a roller conveyor (not shown) or the like, the conveying speed V (m / sec) of the steel material 1 is measured using the laser Doppler velocimeter 2. As shown in FIG. 2, the laser Doppler velocimeter 2 includes two laser light emitters 6a and 6b and one laser light receiver 7.
[0015]
In order to measure the transport speed V (m / sec) of the steel material 1 with high accuracy using the laser Doppler velocimeter 2, as shown in FIG. 2, the laser irradiation light 5a emitted from the laser emitters 6a and 6b. , 5b need to pass through the range M where the steel material 1 passes. In particular, when the upper surface of the steel material 1 is set so as to pass through the center of the range M where the laser irradiation lights 5a and 5b intersect, the measurement accuracy of the transport speed V is improved.
[0016]
In order to measure the transport speed V (m / sec) of the steel material 1 with high accuracy in this manner, the fluctuation of the distance H between the laser Doppler velocimeter 2 and the steel material 1 is suppressed and the steel material 1 is transported in the transport direction. It is necessary to measure the transport speed V from a direction perpendicular to the direction. Here, to measure from the direction perpendicular to the direction in which the steel material 1 is transported means that the laser receiver 7 is disposed in a direction perpendicular to the direction in which the steel material 1 is transported, and the laser reflected light reflected perpendicularly from the steel material 1 8 is received.
[0017]
FIG. 1 shows an example in which the transport speed V is measured from a direction perpendicular to the upper surface of the steel material 1 (that is, a direction perpendicular to the transport direction of the steel material 1). However, in the present invention, the transport speed can be measured from a direction perpendicular to the side surface of the steel material 1 (that is, a direction perpendicular to the transport direction of the steel material 1).
In the manufacturing process of the steel material 1, the steel material 1 is usually conveyed using a roller conveyor. At this time, when the transport speed V is measured from a direction perpendicular to the upper surface of the steel material 1 as shown in FIG. H fluctuates.
[0018]
Alternatively, when measuring the transport speed from a direction perpendicular to the side surface of the steel material 1, when the steel material 1 on the roller conveyor is displaced, the distance H between the laser Doppler velocimeter 2 and the steel material 1 changes.
When the distance H between the laser Doppler velocimeter 2 and the steel material 1 fluctuates in this way, the angle at which the transport speed V is measured also changes, and the measurement accuracy of the transport speed V decreases.
[0019]
Therefore, as shown in FIG. 1, a front distance meter 3 is disposed downstream of the laser Doppler velocimeter 2 to detect the tip of the steel material 1 to be conveyed and to connect the front distance meter 3 to the steel material 1. distance measuring _H F a (mm). Further, a rear distance meter 4 is disposed upstream of the laser Doppler velocimeter 2 to measure a distance H _B (mm) between the rear distance meter 4 and the steel material 1 and to detect a rear end of the conveyed steel material 1. I do.
[0020]
In the present invention, the conveyance velocity V, the distance _{H F,} the continuously measured distance _{H B.}
On the basis of the distance H _B measured by the distance H _F and a rear distance meter 4 as measured in the front distance meter 3, to correct the measured transport speed values V (m / sec). FIG. 3 shows an example of a method of correcting the measured value V of the transport speed. That is, FIG. 3 is a graph showing the relationship between the displacement of the average distance H _AVE (mm) from the center of the range M in FIG. 2 and the measurement error (%) of the conveyance speed. (%) corrected measured conveying speed value V (m / sec) to read and obtain the correction value _V R of the conveying speed (m / sec). The average distance H _AVE (mm) is an average value of the distance H _F (mm) and the distance H _B (mm).
[0021]
On the other hand, a front distance meter 3 disposed downstream of the laser Doppler velocimeter 2 detects the tip of the conveyed steel material 1. FIG. 4 shows this state. Assuming that the distance between the front distance meter 3 and the rear distance meter 4 is D (m) and the length of the steel material 1 is L (m), the distance I (m) between the rear distance meter 4 and the rear end of the steel material 1 is It is represented by the following equation (2).
I = LD (2)
L: Length of steel material (m)
D: Distance between front distance meter and rear distance meter (m)
I: Distance between the rear distance meter and the rear end of the steel material when the front distance meter detects the front end of the steel material (m)
FIG. 5 shows a state in which the steel material 1 is further conveyed in the direction of arrow a and the rear distance meter 4 detects the rear end of the steel material 1. At this time, the distance between the tip of the steel material 1 and the front distance meter 3 is equal to the above-mentioned distance I and is expressed by the following equation (2).
[0022]
This distance I is equal to the distance that the steel material 1 is transported from when the front distance meter 3 detects the front end of the steel material 1 to when the rear distance meter 4 detects the rear end of the steel material 1. Thus the distance I, the time _{t 1} the front distance meter 3 detects the steel 1 tip, the time _{t 2} when _the rear distance meter 4 detects a steel 1 rear, from the correction value _V R of the conveying speed (m / sec) It is calculated by the following equation (3).
[0023]
[Equation 3]

[0024]
I: Distance between the rear distance meter and the rear end of the steel material when the front distance meter detects the front end of the steel material (m)
V _R: correction value of the transport speed (m / sec)
By substituting equation (3) into equation (2), equation (1) is obtained.
[0025]
(Equation 4)

[0026]
In the equation (1), the distance D between the front distance meter 3 and the rear distance meter 4 is fixed to a fixed value, so that no error occurs. Although there is a possibility that an error occurs is the correction value V _R of the transport speed, as described above, the accuracy greatly improved by using the measurement value of the front distance meter 3 and a rear distance meter 4 Have been.
In this way, in the present invention, the length can be measured with high accuracy while the steel material 1 is being conveyed, and high accuracy can be maintained even if the conveyed steel material 1 is displaced on the roller conveyor. Moreover front distance meter 3 and a rear distance meter 4, respectively detect the leading and trailing ends steel 1, and the distance H _F of the steel product _1, since the measurement of H _B, steel 1 tip of the detection device, steel 1 the rear end of the detection device, the measurement device of the distance H _F, need not be installed separately measuring apparatus of the distance H _B. Therefore, the length of the steel material 1 can be measured with a simple device.
[0027]
In the present invention, the conveying speed of the steel material 1 may be constantly measured by the laser Doppler velocimeter 2, or the rear distance meter 4 detects the rear end of the steel material 1 after the front distance meter 3 detects the front end of the steel material 1. The conveyance speed of the steel material 1 may be measured only until the detection. In any case, the same measurement accuracy can be obtained.
[0028]
【Example】
The length L (m) of the steel material 1 was obtained by applying the present invention using the apparatus of FIG. 1 while transporting the steel material 1 using a roller conveyor. The length L of the steel material 1 is a value obtained by Expression (1).
[0029]
(Equation 5)

[0030]
Next, the length of the steel material 1 was actually measured with a tape measure, and an actually measured value L _M (m) was obtained. Thus determined for steel 1 and the length L using measured values L _M, was evaluated error by calculating an index α (4) below. This is an invention example. Note that the closer the index α is to 0%, the smaller the error is.
_{α (%) = 100 × (} L M -L) / L M ··· (4)
On the other hand, as a comparative example, the detection of the distance to the steel material 1 by the rear distance meter 4 was stopped and only the rear end detection was performed, and the front distance meter 3 detected the front end of the steel material 1 and measured the distance. _'As, (5) the length of the steel product 1 L in formula' V _R by correcting the conveyance speed of the steel material 1 from the above measurements was determined (m).
[0031]
(Equation 6)

[0032]
Next, the length of the steel material 1 was actually measured with a tape measure, and an actually measured value L _M (m) was obtained. Thus steel 1 obtained length L 'using measured values L _M, was evaluated error by calculating an index β from equation (6) below. The error is smaller as the index β is closer to 0%.
_{β (%) = 100 × (} L M -L ') / L M ··· (6)
The lengths L and L ′ of 50 steel materials 1 were measured for each of the invention examples and the comparative examples, and the indices α and β were obtained. As a result, the index β was 0.13 to 0.21% in the comparative example, whereas the index α was 0.02 to 0.03% in the invention example. Therefore, according to the present invention, it was confirmed that the length of the steel material 1 can be measured with high accuracy while being transported.
[0033]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, when measuring the length while conveying a steel plate, length can be measured with simple means and high precision.
[Brief description of the drawings]
FIG. 1 is a side view schematically showing an example of a length measuring device of the present invention.
FIG. 2 is a side view schematically showing an example of a laser Doppler velocimeter.
FIG. 3 is a graph showing a relationship between a displacement of a distance and a measurement error of a transport speed.
FIG. 4 is a side view showing a state in which the front distance meter has detected the tip of a steel material.
FIG. 5 is a side view showing a state in which the rear distance meter has detected the rear end of the steel material.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel material 2 Laser Doppler velocimeter 3 Front distance meter 4 Rear distance meter 5 Laser irradiation light 5a Laser irradiation light 5b Laser irradiation light 6a Laser light emitting device 6b Laser light emitting device 7 Laser light receiving device 8 Laser reflected light

Claims (3)

A laser Doppler velocimeter that measures the transport speed of the steel material being conveyed, and a front distance meter that is disposed downstream of the laser Doppler velocimeter to detect the tip of the steel material and measure the distance to the steel material, A rear distance meter disposed upstream of the laser Doppler velocimeter to measure a distance to the steel material and detect a rear end of the steel material; and the laser Doppler velocimeter, the front distance meter, and the rear portion. An arithmetic unit for performing arithmetic processing on data measured by the range finder as an input signal. The conveying speed V (m / sec) of the steel material is measured using a laser Doppler velocimeter, and the tip of the steel material is detected using a front distance meter disposed downstream of the laser Doppler velocimeter. measure the distance H _F of the front distance meter and the steel, to measure the distance H _B between the steel and the rear distance meter using a rear distance meter which is disposed upstream of the laser Doppler velocimeter by detecting the trailing edge of the steel together with the distance H _F and, based on the distance H _B corrects the transport speed V (m / sec), the time t ₁ when the front distance meter detects said tip the rear distance meter time t ₂ which detects the trailing _edge, the correction value V _R of the conveying speed _(m / sec), using the distance D (m) between the front distance meter and the rear distance meter The length L (m) of the steel material is calculated from the following equation (1). Length measurement method comprising Rukoto.

L: Length of steel material (m)
D: Distance between front distance meter and rear distance meter (m)
V _R: correction value of the transport speed (m / sec)
t ₁ : Time when the front distance meter detected the front end of the steel material t ₂ : Time when the rear distance meter detected the rear end of the steel material When the front distance meter detects the leading end of the steel material, it starts measuring the transport speed by the laser Doppler velocimeter, and when the rear distance meter detects the rear end of the steel material, the laser Doppler velocimeter starts measuring. 3. The length measuring method according to claim 2, wherein the measurement of the transport speed is stopped.

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