JPH0437924B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for measuring the width and/or meandering of a strip of hot-rolled steel sheets or the like in a rolling line for hot-rolled steel sheets or the like.

[Conventional technology]

Measuring the width and meandering of this type of band is
This is extremely important in rolling operations, and has been conventionally carried out using various methods.

A typical example of this is as shown in FIGS. 6 and 7, with respect to the material M being conveyed by the conveyance roll 50, an ITV or CCD camera is placed above both sides of the material M.
1 and 51, and a light source 5 that emits light from below to above.
Upon receiving the light from 2 and 52, the side edges of the material M are detected based on the light shielding state by the material M, and based on this, information such as the width, meandering, or camber of the material M can be obtained.

[Problem that the invention seeks to solve]

However, when the material M is transported at high speed, the material M often floats up from the transport roll 50 as shown in FIG. It is measured as the width of the material shown. In order to avoid such errors, it is necessary to install the camera 51 directly above the side edge of the material. It is very difficult to control,
Even if it were possible, the equipment would be expensive. Furthermore, when the material is a high-temperature material such as a hot-rolled steel plate, the camera is located above the material, so the lens on the front of the camera is easily contaminated by dust carried by thermal convection. There are also problems such as water turning into steam, blocking visibility and reducing accuracy.

Other measurement methods include capacitance method and eddy current method, but both have a maximum measurement range of 50 mm.
Moreover, the latter has the disadvantage that it is greatly affected by temperature changes of the target material.

Therefore, in order to solve this problem, the present applicant previously proposed in Japanese Patent Application No. 59-79076 that an ultrasonic distance meter was installed on the outer side of both side edges of the strip, and the transmitted ultrasonic waves We proposed a method that measures the time it takes for an object to hit a surface, be reflected, and return.

However, since the speed of ultrasonic waves depends on the ambient temperature, temperature correction is necessary for accurate distance measurement. However, it is not only difficult to accurately measure the temperature at a measurement position in an actual rolling line, but also there are temporal and spatial temperature changes and fluctuations in distribution. As a result, the measured value will include an error.

[Means for solving problems]

In order to solve such problems, in the present invention,
a support that is installed in a rolling line for a strip and measures the width or meandering of the strip, and is provided outside both side edges of the strip and moves towards and away from the side edges; Using a device equipped with an ultrasonic distance meter attached to each of the supports and measuring the distance to the side edge surface, the ultrasonic distance meter is attached to each of the supports, and the ultrasonic distance meter is within a predetermined distance range from the side edge surface. At the same time, the ultrasonic distance meter measures the distance to each side edge surface using the speed of sound based on the actually measured ultrasonic propagation time between the two ultrasonic distance meters.

[Main points of the invention and its effects]

That is, the main points of the present invention are as follows.

(1) An ultrasonic distance meter was used as the measurement detector. According to this ultrasonic distance meter, there is no problem of visibility being obstructed by water vapor as mentioned above, there are few disturbance elements during detection, high precision measurement is possible, and it is inexpensive and small as a detector. becomes.

(2) The support for attaching the ultrasonic distance meter is moved toward and away from the side edge surface of the strip so that it is within a predetermined distance range. Generally, the band-like body has
There are changes in the width and meandering. Therefore, if the ultrasonic distance meter and the side edge surface of the strip are too far apart, measurement errors may occur as described above, and on the other hand, if the support is fixed,
This is to prevent the width material from coming into contact with the support or causing a bump. Fortunately, in steel plate rolling lines, side guides are generally installed on the entry side of the rolling mill to prevent steel plate sendering and camber.
Focusing on the fact that it moves according to the width dimension of the target material, for example, if this side guide is used as a support for an ultrasonic distance meter, there is an advantage that it can be handled with a slight modification of existing equipment.

(3) Furthermore, the difference from the prior invention is that both ultrasonic distance meters actually measure the propagation time of ultrasonic waves, determine the propagation speed of the ultrasonic waves, and use this as the basis for distance measurement. It is a point.

The sound speed of ultrasonic waves depends on the temperature of the atmosphere, but if the actual sound speed is determined, there is no need for correction by temperature measurement, and moreover, accurate distance measurement becomes possible.

[Specific examples of the invention]

The present invention will be explained below using a specific example of a hot-rolled steel sheet shown in FIGS. 1 to 4.

The material M is conveyed in the direction of the arrow in FIG. 1 over the conveyor rolls 1, 1, . Generally, in order to smoothly introduce material into the rolling mill, hot rolling mills are equipped with
Side guides (drive side and free side) 4D and 4F are provided on both sides of the entrance side. The positions of the side guides 4D and 4F are changed in advance depending on the width of the target material, and are usually set at a distance of 20 mm from one side edge of the material, about 40 mm in total.

In the present invention, these side guides 4
Ultrasonic distance meters 5D and 5F are attached to D and 4F, and are arranged so as to look at the side edge surface of the material M through openings formed in parts of the side guides 4D and 4F. In order to know the position of the Mata ultrasonic distance meter 5D, 5F, the well-known side guide drive device 6D,
Side guides 4D and 4F driven by 6F
and the mill frame, differential transformer position detectors 8D and 8F using a differential transformer, a linear potentiometer, a magnescale, or the like having the mill frame 7 as a fixed point are provided.

Thus, when measuring the distance between the ultrasonic distance meter and the side edge surface of the material M, it is necessary to know the sound velocity of the ultrasonic wave in the relevant atmosphere.
Find this speed of sound in advance. Fortunately, the ultrasonic waves have a considerable spread, and some of them are reflected from the side edges of the material.
Since the remainder also reaches the ultrasonic distance meter on the opposite side, the drive side, free side, or both receive the ultrasonic wave from the opposite side and measure the ultrasonic propagation time (TO) between the ultrasonic distance meters. The ultrasonic propagation velocity (v=lo/to) is known from the distance between the ultrasonic distance meters (lo) and the ultrasonic propagation time (to). Separate ultrasonic distance meters may be used for measuring the speed of sound and for measuring the side edge surface of the material.

Furthermore, ultrasonic waves are applied to the side edge surface of the material M from the ultrasonic distance meters 5D and 5F, and the reflected echoes are received, and the time difference (ti) from transmission to reception is measured.
Calculate the distance li from the ultrasonic distance meter to the side edge surface of the material using equation (1). At i=D, F, measurements and calculations are made on the drive side and free side, respectively.

li=1/2vti (1) At this time, as the propagation speed v of the ultrasonic wave, the sound speed based on the actually measured propagation time to between the ultrasonic distance meters described above is used as the basis for calculation.

When generating ultrasonic waves, the ultrasonic distance meters 5D and 5F on the drive side and the free side simultaneously emit ultrasonic waves using a trigger generator attached thereto. Here, if the trigger output interval is too large, the response to width fluctuations and meandering will deteriorate, so it is better to keep it as short as possible depending on the situation. It is preferable to set it to a time greater than or equal to the time.

FIG. 3 shows an outline of the control. For the sake of explanation, it is assumed here that the ultrasonic propagation time between the ultrasonic range finders is measured by reception from the ultrasonic range finder 5D. Ultrasonic distance meter 5D, 5F by trigger generator 10
The signals that the ultrasonic waves simultaneously generated from
Incorporated into 1D and 11F, and ultrasonic distance meter 5
The signal from D is sent to the side edge surface position detection devices 13D and 13F together with the propagation signal obtained via the ultrasonic distance meter propagation time measurement circuit 12. These side edge surface position detection devices 13D, 13F receive the signals from the side guide position detectors 8D, 8F, calculate the side edge surface position, that is, the distance from the mill center, and also calculate the distance from the mill center via the drive circuits 14D, 14F. A position correction signal is given to the side guide drive devices 6D and 6F to reduce measurement errors, and a side edge surface position signal is output to the width/meandering calculation device 15. Width/
The results obtained by the meandering device 14 are outputted to the rolling mill in order to control the rolling reduction amount, tension, left and right rolling balance, etc.

Next, a method for calculating the width and meandering will be explained with reference to FIG. The illustrated symbols have the following meanings.

○ B _D , B _F : Distance from the rolling mill center of the drive side and free side side guides. This can be determined by measuring the distances e _D and e _F to a fixed point on the mill frame 7 using a side guide position detector fixed to the side guide. Note that the distance of each fixed point from the mill center and various dimensions of the side guides have been measured and known at the time of production.

○ A _D , A _F : Distance between the material side surface of the side guide and the front of the ultrasonic distance meter. Measure when setting up the ultrasonic distance meter.

○ l _D , l _F : Measured distance value to the side edge surface of the material using an ultrasonic distance meter.

○ l _O : Distance between ultrasonic range finders l _O = B _D + A _D + B _F + A _F.

○ G _D , G _F : Distance from the rolling mill center to the side edge of the material.

Thus, the material end face position, width, and meandering can be determined as follows.

(Ultrasonic velocity) If the arrival time of the ultrasonic waves from the opposing ultrasonic distance meter is to, then as mentioned above, the ultrasonic velocity V is V=l _O /to (distance between the ultrasonic distance meter and the end face of the material) If the ultrasonic wave arrival time from the ultrasonic distance meter to the material end face is t _D and t _F , l _D = V × t _D l _F = V × t _F t _D , t _F is the distance when the ultrasonic wave hits the material end face. That's 1/2 of the time it takes to get back to work.

Here, it can be seen that in order to reduce the measurement error caused by the ultrasonic arrival times t _D and t _F , it is necessary to make the ultrasonic distance meter as small as possible with respect to the material.

Normally, a hot rolling line rolls various materials with a width of 600 to 2000 mm, so if an ultrasonic distance meter is fixedly installed at a position of 2000 mm width, it will be possible to
Distance measurement will be performed within a distance range of mm,
Large errors occur when measuring materials with small widths.
On the other hand, as in the example above, if you attach an ultrasonic range finder to a side guide whose total separation distance is usually set to about 40 mm each time the material width is changed, you can always measure at close range. possible, and the measurement error will be small.

(End face position) G _D =B _D +A _D −l _D =B _D +A _D −(l _O /to×t _D ) =B _D +A _D −(A _D +B _D +B _F +A _F /to×t _D ) Similarly, G _F = B _F + A _F − (A _D + B _D + B _F + A _F /to×t _F ) (width) G _D + G _F (Meandering) G _D −G _F /2 Note that the result of meandering calculation is correct. If it's negative, it means it's meandering towards the drive side, and if it's negative, it's meandering towards the free side.

Next, we will discuss the method for discriminating echoes when receiving ultrasonic waves.

1 Discrimination between reflected waves from the material end face and reflected waves from the opposing side guide.

When the material is thin, the ultrasonic waves emitted from the ultrasonic range finder spread considerably, so a considerable amount reaches the opposing side guides and is reflected. Although the side guide is located further away than the end face of the material, since the reflection area is large, the wave may return with an intensity greater than that of the reflected wave from the end face of the material. Therefore, the following methods are used for discrimination.

The time it takes for the reflected wave from the edge of the material to return does not change much because the distance between the side guides can be changed depending on the width of the material (usually 20 mm from the side edge of the material). Therefore, as shown in Fig. 5, a gate signal b is applied to the received signal a after converting the received sound pressure into an electric signal, in the vicinity where there is a possibility that the reflected signal from the material end surface may return. After eliminating the signal outside the gate, the signal with the maximum amplitude is taken as the reflected signal from the end face of the material.

2. Discrimination between the reflected wave from the opposing side guide and the signal from the opposing ultrasonic rangefinder, especially when the two signals have approximately the same magnitude.

In this case, since the intervals between the side guides are not constant, it is difficult to discriminate using the gate method, but it is sufficient to transmit and receive data alternately from the drive side and free side ultrasonic range finders. In this case, the positions of each end face will not be measured at the same time, but if the ultrasonic distance meter interval is about 2000 mm, there will be no interference with the previous emitted wave even if measurements are repeated at 20 msec intervals.
This is sufficient as a measurement response.

3. When the pass line fluctuates greatly due to the operation of the looper, such as between hot rolling stands.

Because the end face of the material may deviate in the height direction from within the measurable viewing angle of the ultrasonic distance meter,
It is necessary to line up multiple ultrasonic range finders in the height direction. In this case, an ultrasonic distance meter that cannot receive reflected waves from the material end surface is produced, but as mentioned above, after converting the sound pressure into an electrical signal, a gate is applied, and the largest amplitude of the signal within the gate is detected. This signal is determined to be a reflected wave from the end face of the material.

〔Effect of the invention〕

As described above, the present invention is based on a distance measurement method using ultrasonic waves, and the support body on which the distance meter is attached is moved toward and away from the side edge surface of the material, so that external conditions such as the presence of water vapor It is possible to measure distances with high accuracy without being affected by the winding, and it is possible to accurately obtain information such as the width of the rope and meandering.
In addition, since the propagation velocity of ultrasonic waves in the relevant atmosphere is determined by actually measuring the ultrasonic propagation time between the ultrasonic distance meters, accurate measurement is possible regardless of the temperature of the relevant atmosphere or its distribution. It can be performed.

[Brief explanation of drawings]

Fig. 1 is a plan view of an installation situation of an example of a device according to the method of the present invention, Fig. 2 is a view taken along the - line, Fig. 3 is an explanatory block diagram of the device of the present invention, and Fig. 4 is a side edge surface of the material. Figure 5 is a time chart, Figure 6 is a front view of the conventional method, Figure 7 is its plan view, and Figure 8 is an explanatory diagram of how dimensions are misrecognized. be. M...Material (steel plate), 1...Transport roller, 2,
3...Rolling upper and lower rolls, 4D, 4F...Side guide, 5D, 5F...Ultrasonic distance meter, 6D, 6F
...Side guide drive device, 7...Mil frame, 8D, 8F...Side guide position detector, 1
0...Trigger generator, 11D, 11F...Side edge surface signal detection circuit, 12...Ultrasonic distance meter propagation time measurement circuit, 13D, 13F...Side edge surface position detection device, 14D, 14F...Drive circuit , 15...Width・
Meandering calculation device.

Claims (1)

[Claims] 1. A device that is installed on a rolling line for strips to measure the width or meandering of the strip, and is provided on the outside of both side edges of the strip and moves toward and away from the side edges; , using a device equipped with an ultrasonic distance meter attached to each of the supports and measuring the distance to the side edge surface; The belt-shaped belt is moved toward and away from the ultrasonic distance meter so that the distance between the two ultrasonic distance meters is within the same range, and the sonic speed based on the measured ultrasonic propagation time between the two ultrasonic distance meters is used to measure the distance to each side edge surface by the ultrasonic distance meter. How to measure body width and meandering.