JPH03211201A - Method and instrument for detecting crack in moving bed in iron powder finishing reduction furnace - Google Patents

Abstract

PURPOSE:To prevent breakage of a moving bed from occurring by radiating light on one side face in the moving bed and detecting the light transmitted through the moving bed on the other side face for the prescribed area to detect a crack in the moving bed. CONSTITUTION:A floodlight 7 is arranged on the upper face of above the moving bed 2 and the light is radiated on the surface of moving bed 2 as square-like with the width of the bed 2 as side. A photodetector 8 is fitted to the position corresponding to the floodlight 7 on the lower face of the moving bed 2 and the area having square-like with the length of about 80% the length in the direction of width of moving bed 2 as side is inspected. In the case when there is any crack on the moving bed 2, the light from the moving bed 7 is transmitted and is caught with the photodetector 8. To a picture processing device 9 from a setter 10, the whole inspection range area S0 of the photodetector 8 is set. Luminescent spot area S1 formed with the light detected with the photodetector 8, is obtd. at the interval of prescribed time. The ratio of this area to the whole inspected range area S0, i.e., a luminescent spot area ratio (r1) is operated. The luminescent spot area ratio (r1) is compared with the limit value ruLl and in the case of r1>=ruLl, it is decided that the crack developed to the moving bed 2 exceeds the limit and this is displayed on a display alarm device 11.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method and apparatus for detecting cracks in a moving bed of an iron powder finishing reduction furnace.

<Prior art> Conventionally, iron powder finishing reduction furnaces continuously heat-treat iron powder in a non-oxidizing atmosphere at 700 to 1000°C; A moving bed, which is a type of conveyor belt, is used for the movement.

Since this moving bed is used continuously under high temperature and tension, it is generally made of copper strips such as iron or stainless steel.

<Problems to be Solved by the Invention> However, the above-mentioned moving bed made of copper strips gradually stretches and becomes thinner during use, gradually forming small cracks, which then expand. There is a problem that it finally breaks.

Therefore, the operator always visually inspects the moving floor surface to check for any abnormalities! ! It is normal to recognize the

However, such periodic visual observation by an operator alone may eventually lead to a breakage accident due to oversight, forgetfulness, or individual differences in judgment.

On the other hand, in order to automatically detect such a crack situation at an early stage, a resonant circuit is embedded in the conveyor belt and a resonant circuit detection sensor installed outside is used to detect longitudinal cracks (for example, Japanese Patent Application Laid-Open No. 1983-1999-1). 165540), or by stretching an optical fiber in the belt width direction at the lower part of the conveyor belt where longitudinal cracks are likely to occur, and connecting a light source to one end of the optical fiber and a phototube to the other end to easily connect and remove it. , a device that detects a vertical tear by detecting a change in the amount of light due to cutting of an optical fiber has been proposed (see, for example, Japanese Patent Application Laid-Open No. 112092/1982).

However, all of these are aimed at conveyor belts made of materials such as rubber, and moving beds made of copper strips used in the high-temperature atmosphere of iron powder finishing reduction furnaces as mentioned above are
It is impossible to apply this method because it has large handicaps such as heat resistance, electrical insulation, and difficulty in installation.

The present invention was made to solve the above-mentioned problems, and it is possible to reliably detect cracks in the moving bed even in an iron powder finishing reduction furnace with a high temperature atmosphere, and prevent breakage of the moving bed. The purpose is to provide a method and apparatus suitable for

<Means for Solving the Problems> The present invention solves the problem of cracks in a moving bed in which iron powder to be heat treated is continuously loaded and transferred in an iron powder finishing reduction furnace having a high temperature and non-oxidizing atmosphere. This is a detection method in which light is irradiated on one side of the moving bed outside the furnace, and the light transmitted through the moving bed is detected in a predetermined observation area on the other side. A movable bed for an iron powder finishing reduction furnace, characterized in that the ratio of the bright spot area to the total observation area area is calculated, and the crack status is determined by comparing this ratio with a preset bright spot area ratio limit value. It is also a crack detection method for detecting cracks in a moving bed made of copper strip suspended in a high temperature, non-oxidizing atmosphere iron powder finishing reduction furnace. a pair of light emitters and light receivers that are provided on a path outside the furnace with a movable bed in between; a setting device for setting the total observation area area value of the light receiver; a light reception signal detected by the light receiver; and the setting device. an image processing device that calculates the bright spot area ratio by inputting a setting signal from the device; a calculation signal of the bright spot area ratio output from the image processing device; and a predetermined limit value of the bright spot area ratio. A crack detection device for a movable bed of an iron powder finishing reduction furnace is characterized by comprising: an alarm display device which compares and calculates the calculated signal and issues an alarm when the calculated signal exceeds a limit value.

<Function> According to the present invention, light is irradiated onto the entire surface of one side of the moving bed outside the furnace, and the light transmitted through the cracks of the moving bed is detected on the other surface, and the transmitted light is detected. Since the ratio of the bright spot area to the total observation area is calculated, this ratio can be compared with a preset bright spot area ratio limit value to determine the crack status, thereby preventing breakage of the moving bed. Is possible.

<Examples> Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a side sectional view schematically showing an embodiment of the present invention.

In the figure, 1 is an iron powder finishing reduction furnace body having a non-oxidizing atmosphere, and is heated to a furnace temperature of, for example, 700 to 1000° C. by being supplied with a heat source (not shown).

Reference numeral 2 denotes a moving bed made of copper strip, which is suspended endlessly between a pulley 3 provided on the inlet side of the furnace body 1 and a pulley 4 provided on the outlet side.

5 is a hopper that supplies iron powder 6 to be subjected to reduction treatment.

Reference numeral 7 denotes a floodlight, which is installed on the upper surface of the movable bed 2 that returns from the pulley 4 on the exit side to the pulley 3 on the inlet side. irradiate.

Reference numeral 8 denotes a light receiver such as a television camera, which is attached to the lower surface of the movable floor 2 at a position corresponding to the floodlight 7, and its field of view is approximately 80% of the length of the movable floor 2 in the width direction. It is adjusted so that a square-shaped area can be observed.

Reference numeral 9 denotes an image processing device, which inputs the amount of light received from the light receiver 8, and uses a setting device 10 to set the light receiver 8 to the area of the area that can be observed on the movable floor 2, that is, the total observation area area 30.
is set.

11 is a display/warning device.

In this way, by configuring the crack detection device by installing the emitter 7 and the receiver 8 so as to sandwich the moving bed 2 returning from the iron powder finishing reduction furnace, if there is a crack in the movable bed 2, the light from the emitter 7 can be detected. Since the light leaks and can be caught by the light receiver 8, the image processing device 9 performs the following processing.

(2) The total observation area area S of the light receiver 8 is set in advance from the setting device 10 to the image processing device 9.

■ Next, calculate the bright spot area SI created by the light detected by the light receiver 8 at a predetermined time interval, and calculate the ratio of the bright spot area SI to the total observation area area S0, that is, the bright spot area ratio r1 as shown below (
It is calculated using Equation 11 and output to the display/alarm device 11.

r+ = (S+ /So) xtoo (%)
--------(1) (1) In the display/warning device 11, the bright spot area ratio rI is displayed quantitatively, for example, in the form of a number and a bar graph along with the change in time. Then, by comparing these bright spot area ratios r+ with the preset limit g1rlIL, if the following formula (2) % formula % (2) holds true, the crack situation that has occurred in the moving bed 2 is determined. It determines that the limit has been exceeded and issues a warning signal.

■ In this way, after the fact, the bright spot area S+ (1=1.2...n) is determined over the entire length of the moving bed 2, and the bright spot area ratio "1" is determined using equation (1). Each time (2
) formula to determine the condition of the crack.

Here, it is natural that the above image processing needs to be performed on the entire length of the moving bed 2. For example, when the speed of the moving bed 2 is 500 m/+min, the width for image processing, that is, the length of the moving bed 2 Assuming that the length in the direction is 1000 square meters, the image processing interval may be set to a period of 2 minutes.

In Figure 2, the horizontal axis shows the number of calendar days of use since replacing the movable bed with a new stainless steel strip, and the vertical axis shows the bright spot area ratio r according to the present invention, that is, the change in the occurrence of cracks in the movable bed. It is something that As is clear from this figure, it can be seen that cracks in the moving bed begin to expand rapidly after about 20 days of use.

In this example, on the 28th day after the start of use, the bright spot area ratio r
! It was determined that the amount reached 0.7%, reaching the limit value determined by conventional visual judgment, so the movable bed was replaced with a new one. Thereafter, by setting this limit value rllL to 0.7% and automatically constantly monitoring the occurrence and growth of cracks in the moving bed, we were able to completely eliminate any accidents involving breakage of the moving bed. .

<Effects of the Invention> As explained above, according to the present invention, it is possible to automatically and timely detect when it is time to replace the moving bed, thereby reliably preventing a large-scale production drop due to breakage of the moving bed. It is possible to prevent this, and it also greatly contributes to labor saving.

[Brief explanation of drawings]

FIG. 1 is a side sectional view schematically showing an embodiment of the present invention;
FIG. 2 is a characteristic diagram showing an example of the relationship between the number of calendar days in which the moving bed is used and the bright spot area ratio. 1... Iron powder finishing reduction furnace furnace body, 2... Moving bed,
7... Emitter, 8... Light receiver, 9...
Image processing device. 10... Setting device, 11... Display alarm device.

Claims (1)

[Claims] 1. A method for detecting cracks in a moving bed in which iron powder to be heat treated is continuously loaded and transferred in an iron powder finishing reduction furnace having a high temperature and non-oxidizing atmosphere. Then, outside the furnace, light is irradiated on one side of the moving bed across the moving bed, and on the other side, the light transmitted through the moving bed is detected for a predetermined observation area, and the bright spot area due to this transmitted light is calculated. A method for detecting cracks in a moving bed of an iron powder finishing reduction furnace, characterized by determining the crack status by determining the percentage of the total observation area area and comparing this percentage with a preset bright spot area ratio limit value. . 2. A device for detecting cracks in a moving bed made of steel strip suspended in the furnace of an iron powder finishing reduction furnace in a high temperature, non-oxidizing atmosphere, wherein the moving bed is installed on a passage outside the furnace of the moving bed. a pair of emitter and light receiver provided on both sides of the light emitter, a setter for setting the total observation area area value of the light receiver, and input of the light reception signal detected by the light receiver and the setting signal from the setter. an image processing device that calculates the bright spot area ratio; and a calculated signal that is calculated by comparing the bright spot area ratio calculation signal output from the image processing device with a pre-given limit value of the bright spot area ratio. 1. A crack detection device for a movable bed of an iron powder finishing reduction furnace, comprising: an alarm display device that issues an alarm when the