JP2552386B2 - Ultrasonic flaw detection method for multi-layer rolls - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic ultrasonic flaw detection method for a multilayer roll for rolling, which includes, for example, an outer layer material and a shaft material.

[Prior Art] As a method of ultrasonically flaw-detecting an entire large cylindrical object such as a roll, there is a method of axially feeding a probe or an object to be inspected while rotating the object to be inspected. JP-A-60-162952 is a conventional example for detecting defects in various directions generated on an inspection object by this method. As shown in FIG. 7, the vertical probe 701 and one or a plurality of oblique angle probes 702 to 704 are arranged around the object W to be inspected and the inside of the object to be inspected is spirally fed. This is a method of detecting defects (a), (b), (c), and (d).

As a conventional example in which flaw detection is performed on the entire inspection object without rotating the inspection object, there is a method disclosed in JP-A-60-50450. As shown in FIG. 8 (1) and FIG. 8 (2), this is a space formed by a plurality of vertical probes 801 and eccentric probes 802 installed on the outer peripheral portion of the inspection object W. The object W to be inspected is conveyed without rotating and the whole internal cross section is continuously detected.

In addition, as a result of flaw detection, a flaw detection range is set in the traveling direction of the ultrasonic wave (depth direction of the object to be inspected), and the height of the echo within this flaw detection range is recorded by a pen recorder or the like. It is general to judge the presence or absence and the number of defects based on the echo height.

[Problems to be solved by the invention]

In a multi-layer roll, there are layers and boundaries as the range to be inspected, but since the depth from the surface and the size and type of defects are different in each range, the range to be inspected by several probes with different frequencies It is necessary to change and inspect. In order to perform such flaw detection with the configuration of the above-mentioned conventional example, it is necessary to change the frequency of the probe and reciprocate a plurality of times, so that the inspection time becomes long. Further, since the penetration depth of the layer at the boundary portion differs depending on the location, the position of the reflection echo from the boundary portion varies with the rotation of the roll and the feeding of the probe. Therefore, the flaw detection range of the probe for flaw detection in the layer must be set so as to avoid this variation, and it is difficult to uniformly detect the flaw in the layer over the entire roll.

Further, it is difficult to distinguish between noise and defect echo only by recording the echo height as a flaw detection result, and it is difficult to quantitatively determine the size and position of the defect.

[Means for solving problems]

The present invention, in an ultrasonic flaw detection method in which a roll or a probe is moved in the axial direction while rotating a roll having a multilayer structure in the radial direction to detect the entire roll, a plurality of probes having different flaw detection frequencies are provided. Arranged so that each ultrasonic wave is vertically incident from the roll surface, a flaw detection range is provided at the boundary portion of the layer or inside the layer for each probe, and ultrasonic waves are generated at regular intervals according to a preset order. Oscillate,
The height and position of the echo is measured as flaw detection data within the flaw detection range, and when the probe with the flaw detection range set at the boundary of the layer is oscillated, the echo position of the ultrasonic wave is used to determine the depth of the boundary. The flaw detection range of the probe that detects the adjacent layer at the boundary is reset to set the start or end point of the flaw detection range so that the flaw detection range of the probe does not reach the boundary, and the fluctuation range of the flaw detection range is reset if necessary. A maximum allowable value is set for the rolls, and by using the flaw detection positions in the circumferential direction and the axial direction and the flaw detection data, the C scope image and the B scope image of the roll are emphasized as necessary by using an enhanced image processing means such as line expansion and noise removal. It is an ultrasonic flaw detection method for a multi-layer roll, which is characterized by being created.

〔Example〕

An example of using the present invention in an automatic ultrasonic flaw detector for a roll having two layers of a multilayer material and a shaft material will be described below.

FIG. 1 is an example of the overall configuration of an automatic ultrasonic flaw detector. The control board 104 controls the device operation such as the rotation of the roll 101 and the feeding of the probe, and uses the output 111 of the encoder 107 attached to the rotation roller 106 to determine the ultrasonic oscillating position in the circumferential direction and the axial direction. The timing signal 108 shown is generated and sent to the personal computer 105. The personal computer 105 controls the order of the probes 205, 206, 207 to be oscillated, controls the flaw detector 103 such as setting the flaw detection range and transmitting the ultrasonic oscillation command 110 synchronized with the timing signal, and the height and position of the echo returned from the flaw detector 103. The B scope and C scope images of the roll 101 are created using the data 109.

FIG. 2 shows a flaw detection range in the depth direction of the roll 101 where each probe is flaw-detected. The probes 205, 206, 207 are installed so that ultrasonic waves are vertically incident from the roll surface 204. In this embodiment, in order to detect a relatively large penetration defect that occurs in the boundary portion 203 of the roll composed of the outer layer 201 and the shaft member 202 and a medium-to-fine defect that occurs in the outer layer,
An inspection range is set for each of the three probes 205, 206, and 207 having different flaw detection frequencies. For example, the low-frequency probe 205 detects a range 208 including the boundary 203 at a deep position, the medium-frequency probe 206 detects an outer-layer entire range 209, and the high-frequency probe 207 detects an outer-layer surface. Range 2 to mid range
Detects 10 fine defects.

The personal computer 105 sends an oscillation command 110 to the ultrasonic flaw detector 103 in synchronization with the timing signal 108 from the control panel 104,
As shown in FIG. 3, ultrasonic waves are oscillated so that the oscillation position 301 has a constant pitch P ₁ , P ₂ . The order of the probes 205, 206, 207 to be transmitted at this time is set in advance in the personal computer, but the probe 207 for detecting fine defects is transmitted more times than the probe 205 for detecting relatively large defects. It is desirable to set to.

The ultrasonic flaw detector 103 causes the fourth inspection every time an ultrasonic wave is transmitted.
As shown in the figure, the echo height h and position d within the flaw detection range 404 set for each probe are returned to the personal computer 105 as flaw detection data. The personal computer 105 has a probe 205, 206, 207, for example, red,
Green and blue are assigned, color depths are associated with the echo heights h of the respective echoes, and the echoes are plotted on the display screen to create the B scope and C scope images of the roll shown in FIG. Here, FIG. 5 (1) shows a C scope image of the defect, and FIG. 5 (2) shows a B scope image. In the B and C scopes, the color is displayed dark at the place where the echo is strongly returned due to the defect. It is also possible to set an appropriate threshold value for the echo height h and not display echoes (noise) below that. Further, since there is a possibility of overlooking a fine defect in which a defect echo is displayed by a continuous line of about 1 pixel, it is possible to use an enhanced image processing means such as expansion processing.

In the case of a multi-layer roll, the depth from the surface to the boundary varies depending on the penetration depth between layers. That is, the position d _B of a reflection echo 602 from the boundary portion in FIG. 6 varies depending flaw location. Even if there is such a change in the boundary position, flaw detection is performed on the entire roll without producing an uninspected region in the outer layer. Therefore, each time the probe 205 is oscillated, based on the reflection echo d _B from the boundary portion. Searching for the depth to the boundary, probe 20
The flaw detection range 209 is reset so that the end point position e of the flaw detection range 209 of 6 is shallower than the boundary position by a constant reset distance Δd. The points to be considered in this resetting are explained below. For example, when a defect or a systematic segregation exists near the boundary, the reflected echo 602 may return from a position different from the depth of the boundary. If the depth to the boundary is calculated based on this reflected echo, an error will occur between the depth and the true boundary, and the flaw detection range 209 of the probe 206 will be reset improperly, which is uninspected. Areas will be created. Therefore, it may be provided in advance variation allowable width with respect echo position d _B from the boundary, when the reflected echo position d _B beyond this variation tolerance varies ignore this echo, previous The use of the reflection echo position d _B of prevents the occurrence of an uninspected area. It should be noted that this allowable variation width can be set based on the variation in the boundary depth in the manufacturing process.

EFFECTS OF THE INVENTION By using the present invention, it is possible to detect flaws in the entire layer without an uninspected area even for a multi-layer roll whose boundary depth varies, and since the flaw detection results are imaged, a pen recorder or the like can be used. As compared with recording, it becomes easier to quantify the size of the defect and grasp the occurrence position, and it is possible to improve the inspection accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an automatic flaw detection device using the present invention,
FIG. 2 is a diagram showing a flaw detection range of the probe, FIG. 3 is a diagram showing an ultrasonic wave oscillating position, FIG. 4 is a diagram showing a reflected echo of the ultrasonic wave, and FIG. 5 is obtained by using the present invention. FIG. 6 is a diagram showing B and C scope images, FIG. 6 is a diagram showing a method of resetting the flaw detection range in the outer layer, and FIGS. 7 and 8 are diagrams showing a conventional example. 101 ... Roll, 103 ... Ultrasonic flaw detector, 205, 206, 207 ... Probe, 208 ... Detecting range of probe 205, 209 ... Detecting range of probe 206, 210 ... Detecting range of probe 207

Claims (3)

(57) [Claims] 1. An ultrasonic flaw detection method in which a roll or a probe is moved in the axial direction while rotating a roll having a multilayer structure in the radial direction to detect flaws in the entire roll, and a plurality of probes having different flaw detection frequencies are used. Are arranged so that the respective ultrasonic waves are vertically incident from the roll surface, and a flaw detection range is provided at the boundary part of the layer or inside the layer with respect to each probe, and the ultrasonic waves are arranged at regular intervals according to a preset order. Oscillate,
The height and position of the echo is measured as flaw detection data within the flaw detection range, and when the probe with the flaw detection range set at the boundary of the layer is oscillated, the echo position of the ultrasonic wave is used to determine the depth of the boundary. The flaw detection range of the probe that detects the adjacent layer at the boundary is reset, and the start and end points of the flaw detection range are reset so that the flaw detection range of the probe does not reach the boundary. A method for ultrasonic flaw detection of a multi-layer roll, characterized in that a C-scope image and a B-scope image of the roll are created by using. 2. The multilayer according to claim 1, wherein a maximum allowable value is set for the reset fluctuation width when resetting the starting point or the end point of the flaw detection range of the layer adjacent to the boundary portion. Ultrasonic flaw detection method for rolls. 3. The ultrasonic flaw detection of the multi-layer roll according to claim 1, wherein an enhanced image processing means such as line expansion and noise removal is used in creating the C scope and B scope images. Method.