JP7147739B2 - Steel flaw detection method and apparatus, and steel manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a steel material flaw detection method and apparatus, and a steel manufacturing method.

When detecting flaws inside steel materials, the steel materials are immersed in water, and ultrasonic flaw detection is used to irradiate the steel materials with ultrasonic waves from a probe through the water, thereby inspecting the steel materials without destroying them. (For example, see Patent Document 1 below).

JP 2012-058077 A

By the way, if oil such as straightening oil adheres to the surface of the steel material, dust will adhere to the surface of the steel material, and the dust will also be mixed in the water in which the steel material is immersed. In addition, if scale (oxide film) is formed on the surface of the steel material and has an uneven surface, when the steel material is immersed in water, the air trapped in the uneven part of the scale becomes air bubbles, In addition to existing on the surface of the water, air bubbles are mixed in the water.

If such dust or air bubbles exist on the surface of the steel material or in the water, they may become noise when detecting flaws inside the steel material by ultrasonic flaw detection, lowering accuracy. Therefore, it is conceivable to provide a noise filter between the steel material and the probe. However, with such a noise filter, it has been difficult to sufficiently remove noise caused by dust particles and air bubbles. The reason is considered as follows.

Since dust and air bubbles have an acoustic impedance of approximately 0 N·s/m ³ , the sound pressure reflectance is approximately 1. In addition, since dust particles and air bubbles in water are flowing in the water, they diffusely reflect ultrasonic waves. Ultrasonic waves are generally attenuated when propagating through an object. Therefore, even if a noise filter is provided between the steel material and the probe, it has been difficult to sufficiently remove noise due to dust and air bubbles.

In addition, in a steel manufacturing method that includes internal flaw detection as a process, sending steel materials that are judged to have internal flaws by ultrasonic flaw detection to subsequent processes as they are will lead to shipping of defective products. Therefore, such steel materials are treated as defective products without being sent to the post-process, or internal flaw detection inspections are performed again, and those that are judged to have no flaws are sent to the post-process. Internal flaw detection, in which noise cannot be sufficiently removed, often results in erroneous detection of flaws, resulting in a problem of poor yield.

In view of the above, an object of the present invention is to provide a method and apparatus for flaw detection inspection of steel materials and a method for manufacturing steel materials, which can improve the accuracy of flaw detection inspection of steel materials using ultrasonic waves.

In order to solve the above-described problems, a steel flaw detection inspection method according to the present invention includes a cleaning step of cleaning the surface of a moving steel by spraying water at a pressure of 2 MPa or more onto the surface of the moving steel, and the cleaning step. and an internal flaw detection step of irradiating the cleaned steel material with ultrasonic waves to detect flaws inside the steel material.

Further, in order to solve the above-described problems, a steel flaw detection inspection apparatus according to the present invention includes cleaning means for cleaning the surface of a moving steel material by injecting water at a pressure of 2 MPa or more to the surface of the moving steel material; and internal flaw detection means disposed downstream of the cleaning means in the movement direction of the steel material and irradiating the steel material with ultrasonic waves to detect flaws inside the steel material.

Further, in order to solve the above-described problems, a method for manufacturing a steel material according to the present invention is such that, after carrying out the above-described steel material flaw detection method according to the present invention, the internal flaws detected in the internal flaw detection step are set in advance. It is characterized in that the steel material that satisfies the above allowable conditions is sent to a post-process for processing.

In the steel flaw detection method and apparatus according to the present invention, water is sprayed onto the surface of the steel at a pressure of 2 MPa or more to wash the surface of the steel, and then ultrasonic waves are applied to the steel to remove flaws inside the steel. Since it is detected, ultrasonic flaw detection can be performed after removing oil and dust on the surface of the steel material and destroying uneven scale. Therefore, even if the steel material is immersed in water during ultrasonic flaw detection, air bubbles do not exist on the surface, and dust and air bubbles do not enter the water.

Therefore, according to the flaw detection method and apparatus for steel materials according to the present invention, flaws inside steel materials can be detected without being affected by noise caused by dust, air bubbles, etc., and deterioration in inspection accuracy can be prevented. Therefore, it is possible to greatly improve the accuracy of ultrasonic inspection of steel materials.

In addition, according to the steel manufacturing method according to the present invention, the accuracy of ultrasonic flaw detection inspection of steel materials is greatly improved. It is possible to suppress the generation of steel materials that have been stopped from being sent to the process, and it is possible to improve the yield.

That is, in the method for manufacturing steel materials according to the present invention, only those products judged to have no problem in the inspection results are sent to the post-process based on the results of the flaw detection inspection, which greatly improves the accuracy of the flaw detection inspection. It is possible to suppress the processing in the process, and to suppress the stoppage of processing other than defective products.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the overall configuration of a main embodiment of a flaw detection inspection apparatus for steel materials according to the present invention; FIG. 2 is a front view showing a schematic structure of the cleaning device of FIG. 1; FIG. 2 is a partial cross-sectional side view showing the schematic internal structure of the cleaning apparatus of FIG. 1 ; 1 is a graph showing an inspection pass rate when a conventional flaw detection inspection method for steel materials is applied and an inspection pass rate when a steel material flaw detection inspection method according to the present invention is applied. FIG. 10 is a graph showing the results of examining the residual rate of marking when the water pressure is changed in the flaw detection inspection method according to the present invention. FIG.

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the steel material flaw detection inspection method, its apparatus, and steel material manufacturing method according to the present invention will be described with reference to the drawings, but the present invention is not limited only to the embodiments described with reference to the drawings.

<Main embodiment>
Principal embodiments of the steel material flaw detection inspection method, its apparatus, and steel material manufacturing method according to the present invention will be described with reference to FIGS. 1 to 5. FIG.

As shown in FIG. 1, a steel flaw detection inspection apparatus 100 according to the present embodiment sprays water onto the surface of a round bar 1, which is a moving steel, at a pressure of 2 MPa or more and 3 MPa or less. It is provided with a cleaning device 130 which is a cleaning means for cleaning. The steel flaw detection inspection apparatus 100 is disposed downstream of the cleaning device 130 in the movement direction of the round bar 1 (on the right side in FIG. 1), and irradiates the round bar 1 with ultrasonic waves to An internal flaw detection device 140, which is an internal flaw detection means for detecting flaws in the interior of the apparatus 1, is provided.

Further, the steel material flaw detection inspection apparatus 100 is disposed upstream (left side in FIG. 1) in the movement direction of the round bar 1 of the cleaning device 130, and is a surface flaw detection means for detecting flaws on the surface of the round bar 1. is provided with the surface flaw detector 110 . The steel flaw detection apparatus 100 is provided between the surface flaw detection apparatus 110 and the cleaning apparatus 130, and includes a marking device 120 which is a marking means for marking flaws on the surface of the round bar 1. .

The surface flaw detection device 110 is a device for detecting flaws on the surface of a round bar 1 oriented in the longitudinal direction (axial direction) along the moving direction by magnetism such as leakage magnetic flux flaw detection. The marking device 120 receives the round bar 1 from the surface flaw detector 110, and sprays a marking agent such as paint onto the flaws on the surface of the round bar 1 detected by the surface flaw detector 110. This is a device that clearly shows the position of the scratch on the surface of the round bar 1.

The cleaning device 130 has a structure as shown in FIGS.
As shown in FIGS. 2 and 3, the front side (the front side of the paper in FIG. 2, the right side in FIG. 3) of the internal hollow casing 131 having a hexahedral shape is provided with a feed port through which the round bar 1 is fed. 131a is formed. A delivery port 131b through which the round bar 1 is delivered is formed on the rear side (left side in FIG. 3) of the casing 131. As shown in FIG.

One end of a water supply pipe 132 is connected to the middle of one side surface (the right side surface in FIG. 2) of the casing 131 near the bottom. A drain pipe 136 for discharging the water 2 inside the casing 131 to the outside is connected to the bottom surface of the casing 131 (bottom surface in FIGS. 2 and 3).

A water supply header 134A is provided on the rear side (left side in FIG. 3) of the inside of the casing 131. The water supply header 134A has a rectangular pipe attached along the rear side. A water supply header 134B is provided on the front side (right side in FIG. 3) of the inside of the casing 131. The water supply header 134B has a square pipe attached along the front side. One end side of the water supply pipe 132 and the lower side of the water supply headers 134A and 134B are connected via a distribution pipe 133 .

Injection nozzles 135Aa, which are nozzles that inject water 2 in a fan-like manner toward a position closer to the rear side (leftward in FIG. 135Ab are attached respectively. Injection nozzles 135Ba, which are nozzles that inject the water 2 in a fan-like manner toward the injection positions of the water 2 by the injection nozzles 135Aa and 135Ab, are located in the middle positions of the upper and lower sides of the water supply header 134B. , 135Bb are attached respectively.

Injection nozzles 135Ac and 135Ad, which are nozzles for ejecting the water 2 toward the center of the casing 131 in a fan shape, are attached to the middle of both sides of the water supply header 134A. Injection nozzles 135Bc and 135Bd, which are nozzles for ejecting the water 2 toward the center of the casing 131 in a fan shape, are attached to the middle of both sides of the water supply header 134B.

That is, the injection nozzles 135Aa to 135Ad and 135Ba to 135Bd can inject the water 2 over the entire circumferential length of the cross section along the direction perpendicular to the moving direction of the round bar 1, that is, over the entire circumferential length of the outer peripheral surface. . Also, the angle θ1 between the injection direction of the injection nozzles 135Aa and 135Ab and the vertical plane is smaller than the angle θ2 between the injection direction of the injection nozzles 135Ba and 135Bb and the vertical plane (θ1<θ2). Injection nozzles 135Aa to 135Ad and 135Ba to 135Bd are made of cemented carbide at injection port portions.

On the other end side of the water supply pipe 132, the water 2 is injected from the injection nozzles 135Aa to 135Ad and 135Ba to 135Bd at a pressure of 2 MPa to 3 MPa. A delivery port of a booster pump 137, which is a pump for delivery, is connected. An electromagnetic on-off valve 138 is provided near the delivery port of the booster pump 137 .

In this embodiment, the water supply pipe 132, the distribution pipe 133, the water supply headers 134A and 134B, the injection nozzles 135Aa to 135Ad and 135Ba to 135Bd, the booster pump 137, the on-off valve 138 and the like constitute injection means.

In the internal flaw detection device 140 shown in FIG. 1, the round bar 1 is fed from the cleaning device 130 into the interior, the round bar 1 is immersed in water, and the steel is irradiated with ultrasonic waves from the probe through the water. This is a device for detecting flaws inside the round bar 1 by doing so.

A flaw detection method for steel using the steel flaw detection apparatus 100 according to the present embodiment will now be described.

When the round bar 1 is fed into the surface flaw detector 110 so that the longitudinal direction (axial direction) of the round bar 1 faces the movement direction, the surface of the round bar 1 is detected by magnetism such as leakage magnetic flux flaw detection. Flaws are detected (surface flaw detection process). The round bar 1 with surface flaws detected is fed from the surface flaw detector 110 into the marking device 120, and is sprayed with a marking agent to mark the positions of the detected surface flaws ( marking process). This marking is performed in order to specify a portion to be subjected to surface flaw removal processing in the surface flaw removal step to be described later.

The marked round bar 1 is sent from the marking device 120 into the inlet 131 a of the casing 131 of the cleaning device 130 and is covered with the casing 131 . The booster pump 137 pressurizes the water 2 so that the water 2 is injected from the injection nozzles 135Aa to 135Ad and 135Ba to 135Bd at a pressure of 2 MPa or more and 3 MPa or less by opening the on-off valve 138 .

The water 2 flows through the water supply pipe 132, the distribution pipe 133, and the water supply headers 134A, 134B and is supplied to the injection nozzles 135Aa-135Ad, 135Ba-135Bd. The water 2 is jetted from the jet nozzles 135Aa to 135Ad, 135Ba to 135Bd toward the surface of the round bar 1 in a fan shape at a pressure of 2 MPa or more and 3 MPa or less, and is jetted over the entire circumferential length of the round bar 1 at high pressure. Attached.

As a result, not only is oil such as correction oil adhering to the outer peripheral surface of the round bar 1 and dust removed, but also the scale floating and uneven on the outer peripheral surface is destroyed.

Here, since the injection nozzles 135Aa to 135Ad and 135Ba to 135Bd are made of a superhard alloy, they are less likely to wear out and can maintain injection of the water 2 at a high pressure of 2 MPa or more for a relatively long period of time. .

Since the injection nozzles 135Aa and 135Ab jet the water 2 in a fan-like manner toward a position closer to the rear side (left side in FIG. 3) than the center position inside the casing 131, the impact force against the However, the water 2 that collides with the outer peripheral surface of the round bar 1 may splash toward the front side of the casing 131 (right side in FIG. 3) and leak from the inlet 131a.

On the other hand, the injection nozzles 135Ba and 135Bb inject the water 2 in a fan shape toward the injection position of the water 2 by the injection nozzles 135Aa and 135Ab rather than the central position inside the casing 131. Collision force becomes smaller. However, the water 2 that collides with the outer peripheral surface of the round bar 1 is not only difficult to scatter toward the front side of the casing 131 (the right side in FIG. It acts as a water curtain to block the splashed water 2.

For this reason, the cleaning device 130 greatly suppresses the leakage of the water 2 from the inlet 131a of the casing 131, so that the surface flaw detector 110 and the marking device located on the upstream side in the moving direction of the round bar 1 and which hate water. It is possible to prevent the water 2 from splashing on the 120. - 特許庁

Injection nozzles 135Aa to 135Ad and 135Ba to 135Bd inject water 2 toward the surface of round bar 1 at a pressure of 2 MPa or more and 3 MPa or less. For this reason, the injection nozzles 135Aa to 135Ad and 135Ba to 135Bd remove oil and dust from the outer peripheral surface of the round bar 1 and break the uneven scale that has floated up. It can be reliably left without being removed (above, cleaning step).

Here, if the pressure of the water 2 is less than 2 MPa, it becomes difficult to reliably remove oil and dust from the outer peripheral surface of the round bar 1 and destroy the uneven scale that has risen. put away. On the other hand, if it exceeds 3 MPa, the marking may disappear, which is not preferable. This is because, when removing the surface scratches by grinding the marked portion (a surface scratch removing step to be described later), if the marking disappears, the surface scratches are not ground even though they actually exist. This is because the round bar 1 will be supplied to the subsequent process with surface scratches remaining.

It is preferable that the injection distance of the water 2 from the injection ports of the injection nozzles 135Aa to 135Ad to the outer peripheral surface of the round bar 1 is 174 mm or more and 298 mm or less. If it is less than 174 mm, the round bar 1 may protrude from the jetting width of the water 2, and the round bar 1 may not be sufficiently washed, which is not so preferable. On the other hand, if it exceeds 298 mm, the collision force of the water 2 against the round bar 1 is greatly reduced, and the scale peeling performance may be deteriorated, which is not so preferable.

The round bar 1 whose outer peripheral surface has been cleaned is fed into the casing 131 of the internal flaw detector 140 from the delivery port 131 b of the casing 131 of the cleaning device 130 . The round bar 1 is immersed in water and irradiated with ultrasonic waves from a probe through the water to detect internal flaws (internal flaw detection step).

At this time, since the oil and dust on the outer peripheral surface of the round bar 1 are removed and the uneven scale is destroyed, even if the round bar 1 is immersed in water, air bubbles will not exist on the surface. Also, no dust, air bubbles, etc. are mixed in the water. Therefore, the internal flaw detector 140 can detect flaws inside the round bar 1 without being affected by noise caused by dust, air bubbles, or the like, thereby preventing deterioration in inspection accuracy.

Therefore, according to this embodiment, it is possible to significantly improve the accuracy of flaw detection inspection of the round bar 1 using ultrasonic waves.

FIG. 4 shows the inspection pass rate when the conventional steel flaw detection method is applied and the inspection pass rate when the steel flaw detection method according to the present invention is applied to round bars in the same state. show. As can be seen from FIG. 4, the inspection method for steel according to the present invention (with a cleaning process (water volume 20 L/min, water pressure 2.6 MPa)) has a higher pass rate than the conventional inspection method for steel (without a cleaning process). increased by 0.26%, ie false positives decreased by 0.26%.

Further, FIG. 5 shows the result of examining the residual rate of marking when the water pressure is changed in the steel material flaw detection inspection method according to the present invention. As can be seen from FIG. 5, it was confirmed that the marking residual ratios were all 100% at pressures of 2.0 MPa, 2.6 MPa, and 3.0 MPa.

Next, a method for manufacturing a steel material according to the present embodiment, which is performed after the above-described flaw detection method is performed, will be described.

The round bar 1 that has been judged to have no problems with the degree of internal damage in the results of the above-described flaw detection inspection, that is, the round bar 1 that satisfies the predetermined allowable conditions for internal damage is sent to the surface flaw removal process. be done. On the other hand, the round bar 1 whose internal flaws do not satisfy the preset allowable condition is not sent to the post-process (in this embodiment, the next step is the surface flaw removal step), but is sent to the post-process. is canceled, or the internal flaw detection inspection is performed again, and when it is newly determined that there is no problem with the extent of the internal flaw, the product is sent to the post-process.

Here, if the degree of internal damage can be diverted to other product types, destinations, etc. that are set to allowable conditions that are more lenient than the initially set allowable conditions for product types, destinations, etc. , it is also possible to determine that there is no problem on the premise that it will be diverted and send it to the post-process. If the internal damage is such that it cannot be reused, it is not sent to the post-process. Note that the allowable conditions set in advance for internal scratches are conditions set in consideration of the number of scratches, the size of scratches, etc., considering the use of the round bar 1, demand, etc. .

The surface flaw removing step is a step of removing surface flaws by grinding the surface of the portion marked in the marking step. Surface grinding is performed so as to grind at least the marked portion, but the grinding range (how much area range including the marked portion is ground) and various conditions such as the grinding depth are determined as appropriate.

The round bar material 1 that has undergone the surface scratch removing process is further sent to a post-process and processed. Here, the post-process refers to all the processing processes that are performed after the round bar 1 that has undergone the surface inspection. That is, it includes all the processes such as the refinement process and the shipping process. In addition, when the steel material which performed the surface inspection is a raw material for rolling, a rolling process is also included.

According to the method for manufacturing the steel material according to the present embodiment, only the round bar material 1 with no problem of internal damage is processed in a post-process (surface damage removal process) and further post-process, it is possible to prevent the defective round bar 1 from being sent to the post-process with respect to internal damage, and actually internal damage is a problem. It is possible to prevent the round bar material 1 to the extent that there is no loss from being stopped without being sent to the post-process, and the yield can be improved.

<Other embodiments>
In the above-described embodiment, the on-off valve 138 is used to switch whether or not the water 2 is supplied. However, the present invention is not limited to this, and as another embodiment, for example, a three-way valve can be used to switch whether or not the water 2 is supplied.

In the above-described embodiment, the pressure of the water 2 injected onto the surface of the round bar 1 is set to 3 MPa or less in the cleaning process, and furthermore, the flaws on the surface of the round bar 1 before being cleaned in the cleaning process are detected. and a marking step for marking the flaws detected in the surface flaw detection step and before being washed in the washing step. However, the present invention is not limited to this.

As other embodiments, for example, the surface flaw detection process and the marking process are not performed, the surface flaw detection process and the internal flaw detection process are not performed continuously, and the surface flaw detection process and the internal flaw detection process are performed continuously. However, when the surface flaw detection process and the marking process are performed after the internal flaw detection process, the marking does not disappear in the cleaning process, so it is possible to spray water 2 at a pressure exceeding 3 MPa in the cleaning process. .

When the surface flaw detection process, the marking process, and the internal flaw detection process are performed continuously, it is preferable to perform the surface flaw detection process, the marking process, the cleaning process, and the internal flaw detection process in this order. This is because the leakage magnetic flux flaw detector used in the surface flaw detection process does not have good resistance to an environment where it is splashed with water. This is because the water 2 can be prevented from entering the surface flaw detection process together with the round bar 1 from the upstream side by positioning the internal flaw detection process downstream of the surface flaw detection process.

Further, in the above-described embodiment, only the round bars 1 which have been found to have no problem in the degree of damage in the internal flaw detection process are not sent to the surface flaw removal process. That is, it includes a surface flaw removing step as a post-process. However, the present invention is not limited to this. As another embodiment, for example, when it takes a long time to determine the degree of internal flaws in the internal flaw detection process, or when the internal flaw detection means and the grinding device for performing the surface flaw removal process are installed in succession, etc. It is also possible to carry out the surface flaw removal process regardless of the degree of internal flaws.

At this time, before sending the round bar 1 to any of the subsequent processes, it is determined whether or not the internal flaws detected in the internal flaw detection process satisfy preset allowable conditions. The round bar material 1 that does not satisfy the condition is not sent to the post-process after the time of determination.

Moreover, in the above-described embodiment, the case of application to the round bar 1 has been described. However, the present invention is not limited to this, and can be applied to steel materials of various shapes including square bars in the same manner as in the above-described embodiments.

INDUSTRIAL APPLICABILITY The method and apparatus for flaw detection and inspection of steel materials and the method for manufacturing steel materials according to the present invention can be extremely beneficially utilized in the steel industry and the like.

1 Round bar material 2 Water 100 Flaw detection device 110 Surface flaw detection device 120 Marking device 130 Cleaning device 131 Casing 131a Inlet 131b Outlet 132 Water supply pipe 133 Distribution pipe 134A, 134B Water supply header 135Aa to 135Ad, 135Ba to 135Bd Injection nozzle 136 Drainage Pipe 137 Booster pump 138 On-off valve 140 Internal flaw detector

Claims (6)

a cleaning step of spraying water onto the surface of the moving steel material at a pressure of 2 MPa or more and 3 MPa or less to clean the surface of the steel material;
an internal flaw detection step of irradiating the steel material cleaned in the cleaning step with ultrasonic waves to detect flaws inside the steel material;
a surface flaw detection step of detecting flaws on the surface of the steel material before being washed in the washing step;
a marking step of marking the flaws of the steel material detected in the surface flaw detection step and before being cleaned in the cleaning step;
A flaw detection inspection method for steel materials, characterized by performing After performing the flaw detection inspection method for steel materials according to claim 1 , the steel materials whose internal flaws detected in the internal flaw detection step satisfy a preset allowable condition are sent to a post-process for treatment. A method of manufacturing steel. After carrying out the flaw detection inspection method for steel materials according to claim 1 , the internal flaws detected in the internal flaw detection step satisfy a preset allowable condition, and the marked portion is removed in the marking step. A method of manufacturing a steel material, characterized in that the steel material from which surface scratches have been removed by surface grinding is sent to a post-process. a cleaning means for cleaning the surface of the moving steel material by spraying water at a pressure of 2 MPa or more and 3 MPa or less onto the surface of the moving steel material;
internal flaw detection means disposed downstream of the cleaning means in the moving direction of the steel material and irradiating the steel material with ultrasonic waves to detect flaws inside the steel material;
surface flaw detection means disposed upstream of the cleaning means in the moving direction of the steel material and detecting flaws on the surface of the steel material;
marking means disposed between the surface flaw detection means and the cleaning means for marking the flaws on the surface of the steel material;
A flaw detection inspection device for steel materials, comprising: In the flaw detection inspection apparatus for steel materials according to claim 4 ,
The cleaning means
a casing having a feed port for feeding the steel material formed on the front side and a feed port for feeding the steel material formed on the back side;
Water is jetted over the entire circumferential direction of the cross section of the steel material along the direction orthogonal to the moving direction of the steel material from the back side inside the casing toward the position closer to the back side than the central position inside the casing, and and spraying water over the entire circumferential direction of the cross section of the steel material along the direction orthogonal to the moving direction of the steel material from the front side inside the casing toward the position closer to the back side than the central position inside the casing. injection means;
A flaw detection inspection device for steel materials, comprising : In the flaw detection inspection apparatus for steel materials according to claim 5 ,
The injection means is
Furthermore, water is jetted from the back side of the inside of the casing toward the center of the inside of the casing over the entire circumferential direction of the cross section of the steel material along the direction perpendicular to the moving direction of the steel material, and the inside of the casing From the front side of the casing toward the center of the inside of the casing, water is jetted over the entire circumferential direction of the cross section of the steel material along the direction perpendicular to the moving direction of the steel material.
A flaw detection inspection device for steel materials characterized by:

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