JPH04354828A - Method for detecting tension of material to be annealed in horizontal continuous annealing furnace - Google Patents

Abstract

PURPOSE:To provide a tension detecting method by which the tension of a material to be annealed can be detected excellently to an extremely low range in a horizontal continuous annealing furnace. CONSTITUTION:In the horizontal continuous annealing furnace 1 on which plural supporting rolls 3a, 3b are provided and through which strip-like or linear material 5 to be annealed passes while supporting with the above-mentional supporting rolls 3a, 3b, by passing through pentration holes 2a, 2b formed to furnace side walls at a center position between the supporting rolls 3a, 3b in the furnace, catenary rate of the material is detected with an optical catenary detector and based on this detected quantity, the tension of the material in the furnace is detected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting tension in a horizontal continuous annealing furnace, and it is an object of the present invention to provide a method for detecting tension in a horizontal continuous annealing furnace that can satisfactorily detect the tension of a material to be annealed down to an extremely low range.

0002

[Prior Art] Generally, in a horizontal continuous annealing furnace for strip, the strip is suspended and supported in a catenary-like manner by support rollers placed inside the furnace and near the furnace inlet and outlet, and the strip is conveyed through the furnace in this state. This is an annealing furnace that performs continuous annealing treatment. In this type of furnace, it is extremely important to measure the catenary amount of slip in the furnace and to accurately control the running state of the strip based on the measurement results.

[0003] As a method for detecting this catenary amount,
Special Publication No. 62-30247 and Special Publication No. 63-6688
No. 3 is proposed. Among these methods, the former method projects a laser beam from a laser oscillator 6 onto the material to be annealed 5 through a hole provided in the furnace body, and captures the laser beam with an image sensor 10, as shown in FIG. This method measures the angle of reflection. In the latter method, an image sensor 11 is placed at the inlet or outlet of the furnace as shown in FIG. This is a method of optically detecting the amount of fall of the material to be annealed 5 relative to the support roll 4.

0004

[Problems to be Solved by the Invention] Among these, the former method, that is, the method of projecting a laser beam onto the material to be annealed and detecting the reflection angle, involves drilling a hole in the refractory material on the ceiling of the furnace. These measuring instruments are exposed to high-temperature radiation inside the furnace, so strict heat protection measures must be taken.
The projected light hits the surface of the material to be annealed, and the light receiving side detects the scattered light, so in the case of materials with high gloss surfaces, it may be difficult to properly detect the reflected light. .

In the latter method, an image sensor is placed at the inlet or outlet of the furnace to detect the inclination of the material to be annealed and the support rollers.
The method of optically detecting the amount of fall of the material to be annealed relative to the roll does not directly monitor the amount of catenary between the support rolls in the furnace. A drawback is that catenary fluctuations between support rolls cannot be detected. An object of the present invention is to provide a method for detecting tension in a furnace that can solve the problems of the conventional method as described above.

[0006]

[Means for Solving the Problems] Therefore, the present invention provides a horizontal continuous annealing furnace which is equipped with a plurality of support rolls and through which a strip or linear material to be annealed is passed through while being supported by the support rolls. In a method for detecting tension in a furnace of a material to be annealed, the amount of catenary in the material to be annealed is detected by an optical catenary detection device through a through hole formed in the furnace side wall at a central position between support rolls in the furnace. Its feature is that it detects the tension in the furnace of the material to be annealed based on the detected amount. The above optical catenary
An image sensor is usually used as the detection device, but a phototube type detection device in which several phototubes are arranged vertically, for example, can also be used.

[0007]

[Operation] According to the present invention, based on the known correspondence between the image obtained by an optical catenary detection device such as an image sensor and the catenary amount of the material to be annealed, the image position is The actual catenary amount can be obtained from Since the relationship between the catenary amount and the actual tension has a correlation as shown in FIG. 4, for example, the actual tension of the material to be annealed in the furnace can be detected based on the actual catenary amount. Therefore, the method of the present invention is an extremely effective and simple method for detecting tension in a furnace in a furnace that performs micro-tension operation.

[0008]

[Embodiment] Fig. 1 shows an embodiment of the present invention, in which a through hole is provided in the furnace side wall at the center position of the in-furnace support rolls 3a and 3b of the annealing furnace 1 so that the material to be annealed 5 can be observed. 2a is provided,
Furthermore, a through hole 2b is formed on the opposing furnace side wall side, symmetrical to the through hole 2a, in order to enable detection of the position of the material to be annealed by an image sensor from the through hole 2a side. It is desirable that these through holes be provided in the center position between as many in-furnace support rolls as possible in the longitudinal direction of the furnace. In particular, in a furnace where the temperature inside the furnace is 1200°C or higher and the material to be annealed 5 with a plate thickness of about 0.1 mm is annealed, excessive tension will lead to immediate breakage, so the tension should be applied at as many positions as possible in the longitudinal direction of the furnace. It is necessary to detect. And this through hole 2
An image sensor 6 is installed on the outside of the furnace a for observing the material to be annealed inside the furnace from the side through the through hole. In the figure, 7 is an image processing device, and 8 is a monitor. The material to be annealed 5 is supported by support rolls 3a, 3b, etc. inside the furnace and support rolls 4 outside the furnace, forming a catenary between the support rolls.

In the method of the present invention, the image sensor 6 detects the amount of catenary in the material 5 to be annealed. Detection of this catenary amount is performed, for example, as follows. Since the atmosphere in the furnace is at a high temperature of 1000 DEG C. or higher, the material to be annealed is red-hot, and the monitor screen of the image sensor 6 becomes as shown in FIG. That is, the inside of the window is divided into small areas and binarized according to the brightness. Since the material to be annealed is bright, it is in the "1" region. In the image processing device 7, after binarizing the video signal into 0 and 1 according to the brightness, the center of gravity value (the center of gravity of the area of the "1" region) is subjected to software processing as shown in FIG. Calculate and confirm the catenary position. The distance between the image sensor position (level) and the line threading level is measured in advance and is used to correct the catenary amount. In this way, the amount of in-furnace catenary of the material to be annealed is detected in real time and with high precision. Then, from this catenary amount, the furnace tension is detected based on the relationship between the catenary amount and the actual tension determined in advance as shown in FIG.

0010

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the amount of catenary in the material to be annealed can be measured in real time and with high precision, and based on this, even minute tensions in the furnace can be easily detected. This effectively prevents troubles such as breakage of the annealed material due to high tension. Furthermore, since the method of the present invention provides a through hole in the furnace side wall, it can be carried out without providing a sealing structure, heat insulation, or cooling structure to the furnace wall. Furthermore, since the running state of the material to be annealed in the furnace can be directly observed, it is also possible to easily take action to stabilize the operation.

[Brief explanation of the drawing]

[Fig. 1] Explanatory diagram showing one embodiment of the present invention

[Fig. 2] An explanatory diagram showing an image captured by an image sensor in the method of the present invention

[Figure 3] Diagram showing the flow of image processing in the image processing device

[Fig. 4] Graph showing the relationship between the image processing output voltage of the image obtained by the image sensor, the catenary amount of the material to be annealed, and the in-furnace unit tension.

[Figure 5] Explanatory diagram showing a conventional tension measurement method using a laser beam

[Fig. 6] Explanatory diagram showing a conventional tension measurement method using an outside-of-furnace image sensor

[Explanation of symbols]

1... Annealing furnace, 2a, 2b... Through hole, 3a, 3b.
...In-furnace support roll 4...Out-of-furnace support roll, 5...Material to be annealed, 6...
image sensor

Claims (1)

[Claims] 1. A method for detecting in-furnace tension of a material to be annealed in a horizontal continuous annealing furnace which is provided with a plurality of support rolls and through which a belt-shaped or linear material to be annealed is passed while being supported by the support rolls. The amount of catenary in the material to be annealed is detected by an optical catenary detection device through a through hole formed in the furnace side wall at the center position between the support rolls in the furnace, and the amount of catenary in the material to be annealed is detected in the furnace based on the detected amount. A method for detecting tension in a material to be annealed in a horizontal continuous annealing furnace, which is characterized by detecting tension.