JP7168862B2 - Steel grinding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a grinding method for steel materials such as steel plates and steel billets, and more particularly to a grinding method suitable for grinding the surface of thick steel plates.

Conventionally, in surface grinding care for removing surface flaws of thick steel plates, workers grind by pressing a small grinding device against the surface of the thick steel plate by hand or by applying their weight. . Therefore, adjustment and control of the grinding depth depended on the experience and intuition of the operator.

Since this grinding work is, needless to say, heavy muscle work, automatic grinding machines for the grinding work have been conventionally proposed. On the other hand, to measure the grinding depth, it is common to measure the ground surface after grinding with some kind of displacement gauge, or measure the steel material itself with an ultrasonic thickness gauge, etc., and measure the grinding depth during grinding. was impossible.

For this reason, automatic grinding machines employ one of the following two methods. The first method is to obtain a table of grinding depth, grinding reaction force, and pressing time in advance, and hold a predetermined reaction force corresponding to a predetermined grinding depth for a predetermined time based on the obtained table. The second method is to control the pressing and extending distance of the grinding wheel on the assumption that the pressing and extending distance of the grinding wheel is equal to the grinding depth.

Further, as a configuration of similar grinding control, there is a technique disclosed in Patent Document 1. Patent Document 1 detects sparks generated in a specific area between a grinding belt and a surface to be ground in a contact roll pressing portion, image-processes the detection signal to measure the amount of spark generation, and determines that the amount of spark generation is within a set range. It is a technique of controlling the pressing force of the contact roll so that it becomes. With this method, the pressing force can be kept constant, but in order to control the grinding depth, it is necessary to investigate and determine the pressing holding time in advance. The idea is similar.

JP-A-7-164318

However, the above prior art has the following problems.

In the first method, in order to set the grinding reaction force to a predetermined value, it is necessary to create a table of grinding depth, reaction force and time in advance. Furthermore, since the hardness of the steel material to be ground differs according to the type of steel, it is necessary to prepare the table for each steel type of the steel material to be ground. For this reason, an exaggerated preliminary experiment is required. Patent Document 1 also has the same problem.

In the second method, the pressing extension distance of the grinding wheel may not be equal to the grinding depth due to disturbances such as deflection due to mechanical rigidity, and correction of the target grinding depth is necessary. Correction values must be obtained in prior experiments.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a steel grinding method capable of controlling the grinding depth with high precision by directly measuring the grinding amount. be.

The gist of the present invention for solving the above problems is as follows.
[1] A disk-shaped grinding wheel, an electric motor that rotates the grinding wheel, an actuator that attaches the grinding wheel to a cylinder shaft and presses the grinding wheel against the surface of the steel material to be ground, and the position of the cylinder shaft of the actuator. , a camera for photographing sparks generated from the contact portion between the grinding wheel and the surface to be ground, and an image processing device for counting the number of sparks from the image photographed by the camera. A steel grinding method for grinding the surface of a steel material using a grinding device,
The cylinder shaft of the actuator is driven in the pressing direction to press the grinding wheel against the surface to be ground until the number of sparks counted by the image processing device reaches a predetermined target number, and the steel material is pressed by the grinding wheel. A method of grinding a steel material, characterized in that the surface to be ground of is ground.

According to the present invention, since the number of sparks (grinding chips) generated during grinding is counted in real time, the amount of iron separated from the steel material by grinding can be measured in real time, and the grinding depth can be controlled with high precision. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an example of an embodiment in which the present invention is applied to grinding a thick steel plate, and is a schematic view seen from a direction orthogonal to a rotating surface of a grinding wheel; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an example of an embodiment in which the present invention is applied to grinding a thick steel plate, and is a schematic view seen from a lateral direction parallel to a rotating surface of a grinding wheel; It is a figure which shows the positional relationship of the radius of a grinding wheel, a grinding arc, and the grinding depth. It is a figure which shows an example of the relationship between the grinding depth and the ground volume. It is a figure which shows an example of the relationship between the number of sparks, and the grinding depth.

The present invention will be specifically described below.

A steel grinding method according to the present invention includes a disk-shaped grinding wheel, an electric motor for rotating the grinding wheel, an actuator for mounting the grinding wheel on a cylinder shaft and pressing the grinding wheel against a surface of the steel to be ground, and the grinding wheel. A cylinder control device for controlling the position of the cylinder shaft of the actuator, a camera for photographing sparks generated from the contact portion between the grinding wheel and the surface to be ground, and counting the number of sparks from the image photographed by the camera. a steel material grinding method for grinding a surface of a steel material using a grinding device having an image processing device, wherein the number of sparks counted by the image processing device reaches a predetermined target number; The shaft is driven in the pressing direction to press the grinding wheel against the surface to be ground, and the grinding wheel grinds the surface to be ground of the steel material.

In the present invention, the steel material to be ground by the disk-shaped grinding wheel is, for example, a thick steel slab produced in the hot rolling process of the iron manufacturing process, a steel slab and a cast slab before being rolled into a thick steel slab, and the like. Examples include, but are not limited to. However, regardless of the type of steel material, the object is grinding performed to remove surface flaws of steel material.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described based on the drawings, taking as an example a case where the steel material is a thick steel slab produced by hot rolling a continuously cast slab.

1 and 2 are diagrams showing an example of an embodiment of the present invention, showing a case where the steel grinding method according to the present invention is applied to a thick steel plate that has been cooled to room temperature after hot rolling. FIG. 1 is a schematic view of a disk-shaped grinding wheel viewed from a direction perpendicular to the rotating surface, and FIG. 2 is a schematic view of the disk-shaped grinding wheel viewed from a horizontal direction parallel to the rotating surface.

1 and 2, a direct-acting cylinder 2 is fixedly attached to a base 11 as an actuator constituting the grinding apparatus 1 used in the present invention. The base 11 is installed above the thick steel plate 12 to be ground. It is configured to be horizontally movable in the left-right and back-and-forth directions with respect to the thick steel plate 12 . A hydraulic cylinder, an air cylinder, or the like can be used as the direct-acting cylinder 2 .

The direct acting cylinder 2 has a projecting cylinder shaft 3 on the opposite side of the base 11, and the cylinder shaft 3 can be extended and contracted with respect to the direct acting cylinder 2 by driving the direct acting cylinder 2. ing. The movement direction and movement amount of the cylinder shaft 3 are controlled by an extension command signal input from the cylinder control device 8 .

An electric motor support base 6 is fixedly attached to the cylinder shaft 3 , and an electric motor 4 is fixedly attached to the electric motor support base 6 . A rotary shaft 5 of the electric motor 4 passes through the cylinder shaft 3 , and a disk-shaped grinding wheel 7 is fixedly attached to the tip of the rotary shaft 5 passing through the cylinder shaft 3 . That is, the rotation of the electric motor 4 causes the grinding wheel 7 to rotate. The cylinder shaft 3 has a bearing function for the rotating shaft 5 and a function to move the electric motor 4 and the grinding wheel 7 toward or away from the surface of the thick steel plate 12 .

The surface of the thick steel plate 12 is ground by driving the direct acting cylinder 2, extending the cylinder shaft 3, and pressing the rotating grinding wheel 7 against the surface of the thick steel plate 12 to be ground. As the thick steel plate 12 is ground, sparks 13 are generated from the contact portion between the grinding wheel 7 and the ground surface of the thick steel plate 12 . A camera 9 is installed to photograph the generated sparks 13 . From the viewpoint of accurately photographing the generated sparks 13, the camera 9 is preferably installed directly above or diagonally above the scattering direction of the sparks 13, or directly laterally or diagonally to the side of the scattering direction of the sparks 13. Furthermore, it is desirable to photograph the sparks 13 from a direction perpendicular to the scattering direction of the sparks 13 .

The camera 9 has a field of view capable of photographing all of a certain vertical section of the generated spark 13 . In addition, since the sparks 13 scatter at a high speed, the camera 9 to be used should be a high-speed image processing camera (a camera capable of capturing many frames per second, for example, A camera capable of capturing 100 frames or more is preferable.

The camera 9 is electrically connected to the image processing device 10 , and the image processing device 10 counts the number of generated sparks 13 based on the captured image transmitted from the camera 9 . The image processing device 10 is electrically connected to the cylinder control device 8, and the image processing device 10 controls the cylinder control device 8 until the number of sparks 13 counted reaches a predetermined target number. sends a signal to stretch in the pressing direction. When the counted number of sparks 13 reaches a predetermined target number, the image processing device 10 instructs the cylinder control device 8 to contract the cylinder shaft 3 of the direct-acting cylinder 2, that is, the grinding wheel. A signal is sent so that 7 is withdrawn from the surface of steel plate 12 . Here, the relationship between the number of sparks and the grinding depth is obtained in advance by experiment or the like.

By grinding in this way, it is possible to precisely grind to a desired grinding depth. Further, as described above, the grinding apparatus 1 used in the present invention has an actuator (linear cylinder 2), electric motor 4, grinding wheel 7, cylinder control device 8, camera 9, and image processing device 10.

In the present invention, the image processing device 10 counts the number of sparks 13 (grinding chips) based on the image captured by the camera 9, and the amount of iron separated from the material to be ground such as the thick steel plate 12 by grinding. is measured. This is based on the following grounds.

Let d be the spark 13, that is, the average volume of grinding chips, and let N be the number of sparks generated. Further, let W be the width of the disk-shaped grinding wheel 7, and let S be the cross-sectional area of the grinding arc. With this setting, the ground volume V is represented by the following equations (1) and (2).

Here, the average volume d is assumed to be the average volume d obtained by measuring the particle size distribution of grinding shavings in advance.

Assuming that the grinding depth is h, the central angle of the grinding arc is θ, the radius of the grinding wheel is r, and the positional relationship shown in FIG. 3 is assumed, the following equations (3) and (4) are obtained. FIG. 3 is a diagram showing the positional relationship among the radius of the grinding wheel 7, the grinding arc and the grinding depth.

Therefore, from the formulas (2) to (4), the ground volume V can be obtained by the following formula (5).

In equation (5), since the width W of the grinding wheel and the radius r of the grinding wheel are determined by the shape of the grinding wheel 7, the ground volume V is a function of the grinding depth h only. The relationship between the ground volume V and the grinding depth h is a monotonically increasing graph as shown in FIG. FIG. 4 is a diagram showing an example of the relationship between the grinding depth h and the ground volume V. As shown in FIG.

On the other hand, from the relationship of the formula (1), the value of the grinding depth h corresponding to the number N of sparks can be uniquely determined. Here, the relationship between the number of sparks 13 and the grinding depth h is prepared in advance as a function.

That is, by counting the number N of sparks in real time, the grinding depth h at that time can be measured. That is, until the number of sparks 13 counted by the image processing device 10 reaches a predetermined target number, the cylinder shaft 3 of the direct-acting cylinder 2 is extended in the pressing direction to press the grinding wheel 7 against the surface to be ground. By grinding the surface to be ground of the fire-grinding material in 7, the grinding depth h can be controlled with high accuracy.

A thick steel plate having a tensile strength of 588 MPa was ground by applying the present invention using the grinding apparatus shown in FIG. As a result of actually measuring the diameter of sparks (grinding chips) generated in this grinding, the average diameter of the generated sparks was 50 μm.

It was assumed that the generated sparks were on average spherical. As a result, the average spark volume d was 5.2×10 ⁻⁴ mm ³ . FIG. 5 shows the relationship between the number N of sparks and the grinding depth h in this case.

In the demonstration experiment, the target value of the number of sparks was preset to 150,000 based on FIG. 5 on the premise of grinding to a depth of 0.15 mm. Using an ultra-high-speed image processing camera, the image processing device counted the number of sparks from the image taken by the ultra-high-speed image processing camera, and when the number of sparks reached 150,000, the grinding wheel was withdrawn from the steel plate surface. .

After grinding, the grinding depth was measured with an ultrasonic thickness gauge. As a result, the grinding depth was found to be 0.15 mm. This grinding depth agreed well with the relationship between the number N of sparks and the grinding depth h shown in FIG.

REFERENCE SIGNS LIST 1 Grinding device 2 Linear cylinder 3 Cylinder shaft 4 Electric motor 5 Rotating shaft 6 Electric motor support 7 Grinding wheel 8 Cylinder control device 9 Camera 10 Image processing device 11 Base 12 Thick steel plate 13 Spark

Claims (1)

A disk-shaped grinding wheel, an electric motor that rotates the grinding wheel, an actuator that attaches the grinding wheel to a cylinder shaft and presses the grinding wheel against the surface of the steel material to be ground, and a position of the actuator that controls the position of the cylinder shaft. Sparks generated from the contact portion between the cylinder control device and the grinding wheel and the surface to be groundContinuously so as to include the timing at which the grinding wheel and the surface to be ground come into contactThe camera to shoot and the image taken by the cameracontained in multiple frames that make up thenumber of sparksAccumulateA steel material grinding method for grinding the surface of a steel material using a grinding device having a counting image processing device,
Determining a target number for counting the number of sparks based on the average volume of grinding swarf generated by grinding the steel material and the total volume of the grinding swarf,
Counted by the image processing devicebeenRuSaida sparkSaidThe grinding wheel is pressed against the surface to be ground by driving the cylinder shaft of the actuator in the pressing direction until the target number is reached, and the grinding wheel grinds the surface to be ground of the steel material. grinding method.

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