JPH03210912A - Elongation percentage meter - Google Patents

Abstract

PURPOSE:To measure elongation percentage with high accurcy from the speed difference of an object by providing a projecting means with which light beams are projected on different two positions of the object on which tension is acted and a photodetecting means with which reflected lights which are obtained from projecting positions are received in an elongation percentage meter. CONSTITUTION:A laser beam LB that is emitted from a laser 33 is projected on the surface of a rolled stock 31 on the inlet and outlet sides of rolling mill through a half-mirror 34 and reflected irregularly from the surface. The laser beam laser beam that is irregularly reflecting is received with photodetectors 38b, 39b and made incident on a photodetecting part 40 through optical fibers 38a, 39a. And the difference of travel speed of the rolled stock 31 is determined from the difference of Doppler shift of reflected light DELTA fb - DELTA fa. Then, elongation percentage can be stably measured with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an extensometer that measures the elongation rate of a rolled material during hot or cold rolling, for example.

[Conventional technology]

The elongation rate of the rolled material during rolling is measured by determining the respective moving speeds of the rolled material at the entrance and exit of the rolling mill.

Figure 4 shows, for example, JP-A-60-148612, JP-A-6
0180615 is an explanatory diagram of a conventional method for measuring the elongation rate of a rolled material.

The rolled material 1 is transferred from the unwinding roll 2 to the rolling roll 3 of the rolling mill 3.
The film is wound onto a winding roll 4 through the space between a and 3a. An inlet defroll 5 that is in contact with the rolled material 1 is provided on the inlet side of the rolling mill 3, and an outlet defrole 6 that is in contact with the rolled material 1 is provided on the exit side of the rolling mill 3. A tachometer 7.8 consisting of a tachogenerator is attached to the rotating shaft of each of the differential rolls 5, 6.

The tachometers 7.8 individually detect the moving speeds V, , V, of the rolled material 1. Accordingly, the elongation rate η of the rolled material 1 is determined by ■s.

[Problem to be solved by the invention]

According to the elongation rate measuring method described above, since the entry and exit side defrolls 5 and 6 are in contact with the rolled material 1, the rolled material 1
Slip may occur against the surface.

On the other hand, those deflation rolls 5.6 wear out. As a result, the measurement error of the moving speed of the rolled material 1 is approximately ±1%, and there is a problem that stable detection is not possible, and the elongation rate of the rolled material 1 cannot always be measured with high accuracy.

For this purpose, a method of detecting the moving speed of the rolled material without contacting the rolled material may be considered. FIG. 5 is an explanatory diagram of the elongation rate measuring method. The rolled material 1 is transferred from the unwinding roll 2 to the rolling mill 3
The material is wound onto a winding roll 4 through the rolling rolls 3a, 3a. Laser Doppler one-way speedometers 9 and 10 are provided on the inlet and outlet sides of the rolling mill 3, respectively, for emitting laser light to measure the speed of an object in a non-contact manner. The speed signals of the moving speeds V, V, and V of the rolled material l detected individually by the laser Doppler one-way speedometers 9 and 10 are given to the subtracter 11, and the subtraction results are divided by the speed difference signal of V, -V. Give to container 12. The divider 12 has the moving speed ■
A velocity signal of , is given.

As a result, the divider 12 calculates the velocity difference V given to it,
-V, the speed difference signal is divided by the speed signal of the moving speed V, that is, the elongation rate of the rolled material 1 is measured according to the calculation contents of equation (11).

However, according to this elongation rate measurement method, the speed measurement error is ±0.3 due to the influence of the speed detection error of each laser Doppler speedometer 9.10 and the fluctuation of the rolling state in the pass line. It will be about %.

Therefore, when measuring the elongation rate under these measurement conditions, the measurement error when measuring the moving speed of the rolled material 1 at the entrance and exit sides of the rolling mill 3 is
Due to the speed measurement error that each has, the obtainable moving speed difference V, -V becomes incorrect. However, ε, ,ε are measurement errors (about 1%) of the moving speeds V, ,V.

By the way, Jε, +ε7: V 1. V@, so if the elongation rate is determined using this method, the measurement error will be large, and there is a problem that the elongation rate cannot be measured with high precision even with this method.

In view of this problem, it is an object of the present invention to provide an extensometer that can constantly and accurately measure the elongation rate of an object on which tension is applied.

[Means to solve the problem]

The extensometer according to the present invention is an extensometer that measures the elongation rate of an object on which tension is applied.
It is characterized by comprising a light projection means for projecting light onto positions, and a light detection means for receiving reflected light obtained from those projection positions.

[Effect]

The light projecting means projects light onto two different positions of the object whose elongation rate is to be measured. The light detection means determines the frequency difference of reflected light from the projection position.

Therefore, the moving speed difference of the object can be directly determined from the frequency difference, and the elongation rate can be measured with high precision.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a schematic diagram of an extensometer according to the present invention, and FIGS. 2 and 3 are explanatory diagrams for explaining the present invention in detail.

First, the invention will be explained in detail with reference to FIGS. 2 and 3.

As shown in FIG. 2, when a laser beam LB directed in the moving direction at a predetermined angle is projected from a laser L onto the surface of, for example, a steel plate A that is moving in the direction of the arrow, the laser beam L
B is diffusely reflected on the surface of the steel plate A at the projection position. When there is a relative movement between the laser L and the steel plate A, a Doppler effect is obtained in which the frequency of the diffusely reflected laser beam LB changes, resulting in a Doppler shift, which is the amount of change in the frequency of the laser beam LB. It will be done.

Here, when the frequency of the laser beam LB emitted by the laser L is f, the frequency F of the diffusely reflected laser beam is F=f+Δf (3), where Δf is obtained as a Doppler shift.

By the way, if the moving speed of the steel plate A is V, the vector of the moving speed ■ is the laser beam LB as shown in FIG.
It can be divided into a moving speed vector V2 that is parallel to V2, and a moving speed vector V2 that is perpendicular to V2. On the other hand, the Doppler shift Δf is Δf=(V+/c) ・F ・
...(4) (where C is the speed of light), and thereby the Doppler shift Δr is the moving speed parallel to the laser beam LB in hectors ■
1 and is obtained as the amount of change in frequency F.

Therefore, by determining the Doppler shift Δf, the moving speed of the steel plate A can be determined.

Now, in FIG. 1, a rolled material 31 pulled out in the direction of the arrow from a rewinding roll (not shown) passes between rolling rolls 32a, 32a of a rolling mill 32 and is wound up by a winding roll (not shown). The laser beam LB emitted by the laser 33 is transmitted to the first optical fiber 3 via the half mirror 34.
The laser beam LB is reflected by the /'%-f mirror 34 and is reflected by the mirror 36 and is made to enter the base end of the second optical fiber 370. The tip 35a (37a) of the optical fiber 35 (37) is located on the entry side (output side) of the rolling mill 32, and the tip 35a (37a) is placed in the direction of movement of the rolled material 31 (in the opposite direction to the movement direction). ), and the optical fiber 35 (37
) The incident angles of the laser beam LB emitted by the laser beam LB into the rolled material 31 are set to θ, (θ, ), and the optical fibers 35 (37) are disposed with their tip portions 35a (37a) fixed.

Incidentally, the incident angles θ and θゎ are selected to be the same angle.

Tip 35a (37a) of optical fiber 35 (37)
Nearby, the first (second) optical fiber 38a (39
The light receiving part 38b (39b) attached to the tip of a),
The light-receiving surface 38c (39c) is fixedly disposed at a position separated from the rolled material 31 by an appropriate distance with its light-receiving surface 38c (39c) facing the projection position of the laser beam LB. Further, the light receiving portion 38b (39b) is selected to have an incident angle θ1 (θ,) and a path-to-road angle. Thereby, the light receiving section 38b (39b) connects the optical fiber 35
The laser beam LB emitted from (37) is diffusely reflected by the rolled material 31, and the reflected light thereof is received. The base ends of the optical fibers 38a and 39a both have a light detection section 40.
The light receiving section 38b is inserted into the light receiving section 38b.

The reflected light received by 39b is made to enter the photodetector 40. The light detection unit 40 is configured such that two incident reflected lights interfere with each other to obtain a frequency difference between the frequencies of the respective reflected lights.

Next, the operation of the extendable needle configured as described above will be explained.

When the laser 33 emits the laser beam LB, the laser beam LB is projected onto the surface of the rolled material 31 on the entry side (output side) of the rolling mill 32 via the optical fiber 35 (36).
It reflects diffusely on its surface. The diffusely reflected laser beam is sent to the light receiving section 3.
8b (39b) receives the light, and the optical fiber 38a (39
The respective laser beams received through a) enter the photodetector section 40. As a result, the light detected by the light detection unit 40 is
The two reflected lights interfere, and a beat frequency, which is the frequency difference between the two reflected lights, is obtained.

That is, the frequency of the laser beam LB is F, and the rolling mill 32
The moving speed of the rolled material 31 on the entry side (output side) of
(Vb), the light receiving section 38b (39b) has a moving speed of 2 due to the above-mentioned Doppler effect.

(2) The Doppler shift Δf, (Δfb) associated with , is obtained as follows. These Doppler shifts Δf3Δf
, is related to the moving speed of the rolled material 31 on the exit side of the rolling mill 32, so that the moving speed difference V, -V, is obtained as (51, (61), and θ1 = θ5, so λ (where λ is the wavelength of light), and since λ and cos θ are constant, by finding the Doppler shift difference f and - to f, the moving speed difference Vb - V, Seek.

In this way, the person of the rolling mill 32, the rolled material 3 on the exit side
The moving speed of 1 is obtained as a Doppler shift, and the moving speed difference Vb-V of the rolled material 31 can be directly determined.

The Doppler shift difference Δfb−Δf1, that is, the beat frequency itself can be measured with an error of the number of paths. Thereby, the elongation rate η is calculated by using the moving speed difference V, -V, obtained in this way.

It can be calculated by Note that the moving speed V on the entrance side of the rolling mill 32 is the Doppler shift Δf obtained by the light receiving section 38b.

Alternatively, the moving speed (2) determined by the tachometer 7 as in the conventional method may be used.

In this way, the difference in the moving speed of the rolled material on the inlet and outlet sides of the rolling mill can be directly determined, so even if an error occurs in the moving speed determined on the inlet side of the rolling mill, it is possible to This means that the elongation rate can be measured with extremely high accuracy compared to the case where the elongation rate is determined using the moving speeds determined respectively on the entry side and the exit side.

In this example, a case was explained in which the elongation rate of a rolled material to which tension is applied is measured, but this is merely an example, and the elongation rate of an object other than a rolled material to which tension is applied may also be measured. can. Furthermore, the light to be projected is not limited to a laser beam.

〔Effect of the invention〕

As described in detail above, the present invention projects light onto two different positions of an object whose elongation rate is to be measured, determines the Doppler shift of the reflected light, and calculates the difference between the Doppler shifts, that is, the projected light Since the difference in moving speed of the object is directly determined from the frequency difference between the frequencies, there is no measurement error in the measuring device itself that determines the moving speed. Furthermore, since the difference in moving speed is measured without contact, the measured value can always be stably obtained. Therefore, there is an excellent effect of providing an elongated needle that can always measure the elongation rate with high precision and stability.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the elongation weight according to the present invention, FIGS. 2 and 3 are explanatory diagrams explaining the invention in detail, FIG. 4 is a diagram explaining the conventional elongation rate measuring method, and FIG. It is a figure explaining other elongation rate measuring methods. 31...Rolled material 32...Rolling machine 33...Laser 35.37...Optical fiber 38b, 39b...
・Light receiving parts 38a, 39a...optical fiber 40・
・・Photodetector part Fig. Fig. Fig. △ a Fig. η Fig.

Claims (1)

[Claims] 1. An extensometer that measures the elongation rate of an object on which tension is applied, comprising: a light projection means for projecting light onto two different positions on the object; and reflections obtained from those projection positions. An extensometer characterized by comprising a light detection means for receiving light.