JPH0618228A - Apparatus for measuring cut length of product - Google Patents

Abstract

PURPOSE:To obtain a highly precise and inexpensive apparatus for automatically inspecting the length of a product having a predetermined cross-section after cutting thereof at a predetermined length. CONSTITUTION:A host computor 1 delivers a cut length command through a cutting control computor 2 to a camera moving unit 13, which then moves a camera 10 to a predetermined position depending on the cut length command. Thereafter the both ends of a member 14 to be inspected is photographed by means of cameras 9, 10. Signals obtained through photographing are then binary encoded by means of an image processor 7 and the length of the member 14 is calculated by means of a personal computor 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the length of a product having a constant cross-sectional shape, for example, a round material or a square material manufactured by rolling during the manufacture or in the final product by image processing.

[0002]

2. Description of the Related Art Products having a constant cross-sectional shape such as round materials, square materials, flat materials, angled materials, channels and the like are manufactured mainly by rolling, cut into a predetermined length, and then shipped as products. Also, during the manufacturing of the product,
It is necessary to control the length for the convenience of the subsequent process.

A product having a constant cross-sectional shape as described above is processed into a desired cross-sectional shape, then conveyed by means such as a roller table, and a tip cutting positioning stopper (hereinafter referred to as a stopper). Stop and cut with a saw such as a saw or shear. At this time,
Since the position of the stopper is adjusted to a predetermined position in advance, it is possible to cut into a desired length. Therefore, conventionally, the length is hardly measured by the measuring device after that, and only a part of the product is extracted and inspected by human work.

However, at the time of cutting as described above, the feed roll of the conveying means is worn, or the tip is bounced when it hits the stopper, so that the tip is not in contact with the stopper, Sometimes it disconnects. In this case, the length becomes short, which results in mixing into other normal products. In particular, demands for product dimensions have recently become strict, and it has become necessary to develop a cutting technique that eliminates such short cutting.

As an apparatus for dealing with this problem, an apparatus has been invented for measuring dimensions by image processing using a television camera. The invention described in Japanese Patent Application Laid-Open No. 3-191806 targets a hot steel slab after slabbing and rolling, and the hot steel slab on a transport table is a TV camera for measuring length at equal intervals along the table. Is arranged, the edge position of the target steel slab is obtained from the output signal obtained from the television camera by the image processing device, and the length is calculated from the data.

[0006]

When the cutting length is measured by the above-mentioned length measuring device, there are problems described below. That is, in this length measuring device, since the cameras are arranged at equal intervals and the entire length of the product is imaged, the imaging range of one camera is widened, which is problematic especially when high measurement accuracy is required. Become. A CCD camera generally used for imaging a product is a CCD camera having a plurality of pixels inside.
Although it has a (solid-state image sensor), when the field of view becomes large, the length per pixel becomes long and the measurement accuracy deteriorates. Therefore, the method of imaging the entire length of a product does not require very high accuracy and is convenient when measuring steel pieces of different lengths at the same time, but it is necessary to inspect products with strict tolerance of cutting length. In that case, a large number of cameras are required to improve the measurement accuracy, which increases the equipment cost.
It is an object of the present invention to provide a cutting length measuring device for a product, which can cope with products having a wide range of cross-sectional dimensions and can perform highly accurate measurement with a small number of cameras.

[0007]

A cutting length measuring device of the present invention developed to solve the above-mentioned problems, is a CCD camera for picking up an image near one tip of a product and an image for picking up another tip near the other end. CCD camera, an image processing device that binarizes the video signal obtained from the camera according to the brightness level, and detects the positions of both ends of the product, and the positions of both ends obtained from the image processing device. A data processing device for calculating the length of each product from data, and at least one of the cameras is provided with a camera moving device capable of moving the camera in the longitudinal direction of the product.

In the present invention, the CCD camera means a camera provided with a solid-state image pickup device called CCD as described above. There are various types of CCDs in terms of the number of pixels, and in order to obtain high measurement accuracy, it is better to use a CCD with a larger number of pixels. Therefore, it is necessary to select an appropriate one in consideration of the equipment price and the required measurement accuracy.

The CCD can detect the intensity of incident light on a pixel-by-pixel basis and outputs an analog signal that changes according to the intensity of light. In the image processing device, the CCD
The analog signal obtained from each pixel is binarized by providing a certain threshold value. This threshold must be a value that allows the position of the product tip to be clearly detected.

In the data processing device, the number of pixels in the portion where the product exists in the imaged visual field is counted using the signal binarized by the image processing device. Then, the product length is calculated from the distance between the two cameras stored in advance and the number of counted pixels, and the product length is output to a CRT or the like, or if an abnormal product discharging device is provided, this device is used. Send instructions to remove short cut products.

This is not necessary when the product to be measured has a high temperature and sufficient light is emitted from the product itself to be detected by the CCD, but if not, it is illuminated to illuminate the product. The length is measured by detecting the reflected light with a camera.

In many cases, a product cutting machine simultaneously cuts a plurality of pieces in order to improve productivity. In this case, it is necessary to be able to measure the lengths of a plurality of products at the same time. C
Some CDs have pixels lined up in only one direction, and some have pixels lined up in two directions. When the former camera with CCD is used, one set (2 units) is used for each product. ) Each requires a camera. For example, cut 10 at the same time,
When inspecting, 20 cameras are required for the front and rear ends. Further, it is desirable that the installation angle of the camera can be measured without any adjustment except during the repair and inspection of the equipment, but when the product temperature is high, the angle may be slightly changed due to heat.

When measuring the length under such conditions,
It is preferable to use a CCD in which pixels are arranged in two directions. That is, as shown in FIG. 3, a use area within the field of view 19 of the camera is set for each product (hereinafter, this area is referred to as a window).
By doing so, the length of many products can be measured at the same time with one set of cameras, and even when the installation angle of the cameras changes due to heat of the products, etc., the position of the products in the field of view of the camera changes. This can be dealt with by adjusting the position of the window 18 to an appropriate position.

Further, when the angle of the camera changes in the longitudinal direction of the product due to heat or the like, a deviation occurs between the distance between the two cameras stored in the data processing device and the actual distance, and the measurement is performed. Affects the accuracy of the length that is given. A standard TP of known length is regularly used for this problem.
Can be dealt with by, for example, measuring the object or installing an object as a mark in the field of view of the camera and taking an image of the object to update the value stored in the data processing device.

The camera moving device is provided so that both ends of the cut product can be freely adjusted so as to be within the field of view of the camera, and products of various lengths can be measured with a small number of cameras. There is. If one end position of the product is fixed by the material aligning stopper when measuring the length, the moving device may be attached only to the camera that images the other end. The movement amount (camera position) needs to be measurable so that the camera can be easily adjusted to a desired position when moving. For example, the rotation speed of the camera moving motor can be measured by a rotary encoder, and the moving distance can be obtained from the rotation speed.

When using illumination, it is necessary to attach a camera and illumination together to a moving device so that a sufficient amount of light is applied to the edge of the material regardless of the product length. Is.

[0017]

The length measuring procedure by the apparatus of the present invention will be described below. First, the position of the CCD camera is adjusted by the camera moving device according to the position of the end of the cut product. Then, the vicinity of both ends of the product cut by the two cameras is imaged, and an analog signal according to the optical change of the imaged image is output for each pixel of the CCD.

Next, the image processing apparatus binarizes the analog signal. By this binarization processing, the existing position of the product can be clearly detected. The digital signal obtained by this processing is sent to the data processing device. In the data processing device, the digital signal and the previously stored 2
Calculate the product length from the value of the distance between the cameras.

[0019]

EXAMPLES The case where the apparatus of the present invention is applied to the length measurement of a steel bar manufactured by hot rolling will be described to clarify the characteristics thereof.

The manufacturing process of a steel bar, which is a product, will be described below with reference to FIG.
Will be briefly described. First, scrap is melted in an electric furnace to adjust the chemical composition, and then a slab is manufactured by continuous casting. This slab is slabbed and hot-rolled by a large rolling mill to produce a steel slab having a 160 mm square cross section. After that, the steel slab is reheated and hot-rolled by a small-medium rolling mill to obtain a steel bar 14 having a desired size.

The steel bar produced has a length of 9 mm for cooling.
It is lined up on the 0 m primary cooling floor. Here, after cooling for a predetermined time, a number of steel bars determined in accordance with the cross-sectional dimension are simultaneously conveyed, and the cold shear 16 cuts one end of the material with the stopper 17 aligned. Here, the stopper 17 is adjusted in advance to a position such that the length of the steel bar after cooling becomes the target length.

The cut steel bar 14 is conveyed to a position where the tip of the bar 14 hits the material alignment stopper 15. Immediately after this transport takes place, the cut length is measured by the device of the invention. The steel bar whose length has been measured is cooled again in the secondary cooling bed,
After binding, they are shipped to each user.

Next, the system configuration of the cutting length measuring apparatus according to one embodiment of the present invention will be described with reference to FIG.
As described above, the steel bar 14 cut by the cold shear 16 is transported and the tip positions thereof are aligned by the material alignment stopper 15. A CCD camera 9 is installed above the material alignment stopper 15, and another CCD camera 10 is provided near the rear end of the steel bar 14, and each camera has a tip of the steel bar 14 as a material to be measured. Section and rear end are imaged. Since the position of the tip of the steel bar 14 at the time of image capturing is determined by the material alignment stopper 15, the position of the camera 9 that images the tip is fixed (the installation angle and position are finely adjusted in consideration of the influence of heat). You can do that.) On the other hand, the camera 10 for imaging the rear end portion is attached to the camera moving device 13 so that the camera 10 can be adjusted to an appropriate position according to the length of the product.

As described above, the steel bar 14 is cooled to the primary cooling floor and then conveyed to the position where the apparatus of the present invention is installed. Therefore, the steel bar 14 itself does not emit visible light. Therefore, in order to detect the positions of both ends of the steel bar 14, the illuminations 11 and 12 are provided adjacent to the cameras 9 and 10. In particular, the illumination 12 that illuminates the rear end of the steel bar 14 is attached to the camera moving device 13 so that the vicinity of the rear end of the steel bar 14 can be illuminated regardless of the length of the product.

This camera moving device 13 is connected to the disconnection control computer 2, and further the host computer 1
It is connected to the. The two cameras 9 and 10 are 512 in length and width.
A CCD having pixels is provided inside and is connected to an image processing device 7, and the image processing device 7 is connected to a personal computer 6 which is a data processing device.

The length of the steel bar 14 must be converted to the length at room temperature after the length at the time of measurement is obtained. Therefore, a scanning radiation thermometer 8 is provided above the steel bar 14 to measure the temperature of the steel bar 14 when measuring the length, and the measurement result is sent to the personal computer 6. The personal computer 6 is the aforementioned host computer 1, disconnection control computer 2 and sequencer 5.
And the secondary cooling floor control computer 4 and the abnormal product discharging device 3.

Next, the procedure for measuring the length and discharging the abnormal product by the cutting length measuring device of the present invention will be described. The host computer 1 includes a steel type, a weight of the steel bar 14 to be rolled,
Data such as the number of pieces and the cutting length are input in advance. Then, the host computer 1 sends to the cutting control computer 2 the data necessary for automatically performing the predetermined cutting such as the number and the cutting length. The cutting control computer 2 is a cold shear 1 for cutting the steel bar 14.
6 to specify the cutting conditions, and the camera moving device 13
Also, the cutting length data is sent, and the camera moving device 13 moves the camera 10 to a predetermined position according to the cutting length.

At this time, since the moving amount is grasped by the rotary encoder provided in the camera moving device 13, the camera 10 can be automatically moved to a predetermined position. After moving the camera to a predetermined position, both ends of the steel bar 14 are imaged while the temperature of the steel bar 14 is measured by the scanning radiation thermometer 8, and the image data is obtained by the image processing device 7.
Then, the temperature data is sent to the personal computer 6.

In the image processing device 7, the image is obtained by imaging.
Of the analog signal corresponding to each pixel of 512 × 512, a region where the tip portion of the steel bar 14 is imaged is set as the window 18 as shown in FIG.
The corresponding analog signal is binarized with an appropriate threshold value. By this binarization processing, the region in which the steel bar 14 is present in the window 18 is set to 1, and the region other than that is set to 0 to be a digital signal to be distinguished.

The digital signal obtained by the binarization process is sent to the personal computer 6, and the number of pixels in the region where the steel bar 14 exists in the window 18 at the leading end and the trailing end (hatched portion in FIG. 4). ) Is counted. From this number of pixels
The length L of the steel bar 14 at the time of measurement can be obtained by the equation (1). (See Figure 4)

[0031]

[Equation 1]

L ₁ : Distance from the end of the steel bar window to the center of the rear end of the steel bar L ₂ : Length of the field of view of the camera in the longitudinal direction of the steel bar W: Number of pixels in the direction perpendicular to the steel bar X ₁ : Window of the steel bar front end of the number of pixels in the region of overlap with bars X _2: steel bar out of the rear end window, the number of pixels in the region overlapping with the bars Y _1: steel bar tip window bars longitudinal number of pixels Y _2: a steel bar Number of pixels in the longitudinal direction of the steel bar in the rear window

Next, the cutting length obtained by the equation (1) is converted into the length at room temperature by the temperature value measured by the scanning radiation thermometer 8, and the converted value is displayed on the CRT of the personal computer 6, and at the same time, the predetermined value is displayed. Judge whether it is within the tolerance of. if,
If it is within the tolerance, do nothing. However, if it is out of the tolerance, it will be notified to the operator with an abnormal lamp, etc.
The computer 6 notifies the secondary cooling floor control computer 4 via the sequencer 5 that an abnormal product has occurred, and the abnormal product discharging device 3 removes the corresponding steel bar.
By the above procedure, it is possible to automatically inspect the cutting length and discharge the abnormal product.

In the apparatus of the present invention, the imaging range of one camera is limited to the vicinity of the end of the steel bar 14 as the material to be measured. In this embodiment, the length of the visual field is 400 mm in length and width. Was set. As a result, the length per pixel is 0.78
mm (= 400 mm / 512), and the required length tolerance for a steel bar with a length after cutting of 5000 to 7000 mm (the difference between the upper and lower limits is usually 40
We were able to secure sufficient accuracy with a small number of cameras to guarantee (mm).

Further, by effectively utilizing the visual field range of the cameras, in the case of one set (two) of cameras with a round bar of φ16 to φ42, seven can be inspected at the same time, and the equipment cost is low. It was possible to obtain a great effect in improving the quality of the cut length.

[0036]

As described above, since the cutting length measuring device for a product according to the present invention is provided with the camera moving device,
Two cameras can image the vicinity of both ends of the product regardless of the length of the product, making it possible to automatically perform highly accurate dimensional inspection with inexpensive equipment. Therefore, it goes without saying that the effect of labor saving is great, but it is possible to sufficiently cope with the case where a stricter cutting length is required.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a cutting length measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a flow of carrying a steel bar, which is a material to be inspected, according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a window setting method and the fact that one camera can inspect a plurality of inspection materials at the same time.

FIG. 4 is a diagram for explaining a cutting length calculation method.

[Explanation of symbols]

1 Host computer 2 Cutting control computer 3 Abnormal product discharge device 4 Secondary cooling floor control computer 5 Sequencer 6 Personal computer 7 Image processing device 8 Scanning radiation thermometer 9, 10 CCD camera 11, 12 Illumination 13 Camera moving device 14 Steel bar 15 Material alignment stopper 16 Cold shear 17 Stopper 18 Window 19 Camera view

Front page continuation (72) Inventor Motofumi Yamada 1 Wanowari, Arao-cho, Tokai-shi, Aichi Aichi Steel Co., Ltd.

Claims (1)

[Claims] 1. A CCD for picking up an image near one end of a product
A camera, a CCD camera that captures an image near the other tip, an image processing device that binarizes a video signal obtained from the camera according to a brightness level, and detects positions of both ends of the product, From the position data of both ends obtained from the image processing device,
A data processing device for calculating the length of each product, wherein at least one of the cameras is provided with a camera moving device capable of moving the camera in the longitudinal direction of the product. .