JP6170857B2 - Ring material shape measuring method and shape measuring device - Google Patents

Description

  In the present invention, when a ring material in which concave portions and convex portions are formed on the outer peripheral surface and the inner peripheral surface is hot-rolled, the uneven shape formed on the outer peripheral surface of the ring material is obtained using a light cutting method. The present invention relates to a method for measuring the shape of a ring material to be measured.

  When a large ring material is hot-rolled using a rolled material such as a titanium alloy, a ring rolling machine is used. This ring rolling mill has a king roll that rotates a cylindrical rolled material, a mandrel roll that faces the king roll and reduces the rolled material, maintains the roundness of the rolled material, and the rolled material is horizontal. The centering roll is held so as not to move in the direction, and the axial roll is held so as not to move in the axial direction (vertical direction) when the rolled material is rolled.

In such a ring rolling mill, while rotating the ring-shaped rolled material around the axis, the mandrel roll arranged inside the rolled material is rolled down toward the king roll arranged on the facing side. Roll until desired shape and outer diameter.
At least one of the king roll and the mandrel roll provided in the ring rolling mill may be configured with a profile having a protrusion and a depression on the roll surface. By carrying out hot ring rolling using a king roll and a mandrel roll having a profile having this protruding shape, an irregularly shaped large ring material having a convex part or a concave part on the outer peripheral surface can be produced.

When performing hot rolling from a cylindrical rolled material to a ring material using a ring rolling machine as described above, the shape of the convex portions and concave portions of the ring material is measured in real time during the ring rolling. This is a very important matter for achieving the target shape and dimensional accuracy (roundness and outer diameter).
As a technique for measuring the shape of such a ring material, there is a method of measuring the shape of an outer peripheral surface or the like using a contact type diameter measuring machine or a point type laser distance meter.

  However, since the shape measuring method described above measures the shape of the ring material at a certain position, such as the height of the ring material at a certain position and the diameter of the ring material at a certain position, a plurality of convex portions (profiles) In the case of a ring material having a ring material, it is necessary to provide as many measuring instruments as the number of the convex portions, which may increase the manufacturing cost of the ring material. Therefore, it is difficult to employ in an actual hot ring rolling process.

Also, in the hot ring rolling process, hot ring rolling is performed while the attitude of the ring material is tilted, or hot ring rolling is performed with a difference in the vertical diameter of the ring material. Therefore, it is difficult to accurately grasp the shape of the ring material by the shape measuring method that measures the shape at each point described above.
Therefore, there is a method of measuring the shape of the outer peripheral surface of the ring material by performing two-dimensional measurement using a light cutting method. For example, Patent Document 1 discloses a method for measuring the shape of a tire whose measurement target is not a hot-rolled ring material but whose shape is substantially ring-shaped.

  Patent Document 1 discloses a tire that is provided with light irradiation means for irradiating slit light on a predetermined range of a tire shape detection target surface and a predetermined position corresponding to the light irradiation means, and irradiated with slit light by the light irradiation means. An image pickup means for picking up an upper slit image, a shape detection means for detecting the shape of a tire shape detection target surface based on the slit image picked up by the image pickup means, and a tire shape detected by the shape detection means There is disclosed a tire shape determination device having a comparison means for comparing the vehicle with a predetermined reference shape and a determination means for determining the quality of the tire based on a comparison result by the comparison means.

Japanese Patent Laid-Open No. 11-138654

Conventionally, in order to produce a ring material having a target shape and an outer diameter, the uneven shape of the ring material is measured using a contact type diameter measuring machine or a point type laser distance meter during hot rolling, From the measured results, the hot ring rolling conditions such as the position of the centering roll and the axial roll of the ring rolling mill and the feed speed of the mandrel roll are controlled.
However, when hot ring rolling is performed using a ring rolling mill having a king roll with a profile having a protrusion shape in order to produce a ring material, it is difficult to obtain a target shape and outer diameter. There was something wrong.

  During hot rolling, a black oxide layer (hereinafter sometimes referred to as a black skin) is formed on the outer peripheral surface of a ring material (for example, a titanium alloy ring material). The inventors of the present application have found from the track record of rolling that the black oxide layer is present in a large amount in the convex portion of the ring material and is small in the concave portion. Therefore, in the case of the technique using the optical method disclosed in Patent Document 1, a large number of light receiving luminance deficiencies and shape misdetections due to the influence of the black oxide layer occur, and the shape measurement of the ring material is accurately performed. It was difficult to measure.

That is, with the conventional optical cutting technique, it may be difficult to accurately measure the shape of the ring material during hot rolling.
Therefore, in view of the above problems, the present invention accurately measures the profile shape of the ring material in real time without being affected by the scale such as an oxide layer when the ring material is manufactured from the ring-shaped rolled material. An object of the present invention is to provide a ring material shape measuring method and a measuring device for the same.

In order to achieve the above object, the present invention takes the following technical means.
The ring material shape measuring method according to the present invention uses a ring rolling mill having a king roll, and a “rolled portion” that is a portion that is rolled down in the axial direction and a “unrolled portion” that is a portion that is not rolled down. In the method for measuring the shape of the ring material, the profile of the outer peripheral surface of the ring material is measured using a light cutting method when the ring material formed on the outer peripheral surface is hot-rolled. The outer peripheral surface is irradiated with slit light, the outer peripheral surface of the ring material irradiated with the slit light is imaged, and the captured image is scanned to obtain a light cutting line. Based on the above, the profile shape of the ring material is measured, and when scanning an image corresponding to the inferior part, the position with the highest luminance is determined as the light cutting line in the inferior part, Image corresponding to uncrushed lower part When scanning, from the position of the light cutting line obtained from the image corresponding to the inferior part and the outer shape of the king roll, set a search area to search for the optical cutting line in the uncompressed part, Within the set search region, the position with the highest luminance is determined as the light cutting line at the uncompressed lower portion.

  Preferably, when measuring the shape of the ring material, an irradiation image in which the outer peripheral surface of the ring material is irradiated with slit light is captured and the outer peripheral surface of the ring material is irradiated with slit light. A non-irradiated image that has not been taken is obtained, a difference image obtained by taking a difference between the irradiated image and the non-irradiated image is obtained, and by scanning the difference image, an optical cutting line is obtained, and the obtained optical cutting line is obtained. The profile shape of the ring material may be measured based on the above.

The shape measuring device for a ring material according to the present invention uses a ring rolling mill having a king roll, and a “rolled portion” that is a portion that is crushed in the axial direction and a “non-rolled portion that is a portion that is not crushed” In the ring material shape measuring apparatus for measuring the profile shape of the outer peripheral surface of the ring material using a light cutting method when the ring material formed on the outer peripheral surface is hot-rolled, Light for obtaining an optical cutting line by scanning an irradiation unit that irradiates slit light to the outer peripheral surface, an imaging unit that images the outer peripheral surface of the ring material irradiated with the slit light, and the captured image A cutting line extraction unit and a shape measurement unit that measures the profile shape of the ring material based on the obtained light cutting line, the light cutting line extraction unit being an image corresponding to the indentation When scanning When the image corresponding to the uncompressed portion is scanned, the position of the light cutting line obtained from the image corresponding to the indented portion and the king are determined. A search area for searching for a light cutting line in the uncompressed lower part is set from the outer shape of the roll, and the highest brightness position is determined as the light cutting line in the uncompressed lower part in the set search area. It is characterized by.

  Preferably, the imaging unit captures an irradiation image in which slit light is irradiated on the outer peripheral surface of the ring material, and a non-irradiation image in which slit light is not irradiated on the outer peripheral surface of the ring material. The optical cutting line extraction unit obtains a difference image obtained by taking a difference between the irradiation image and the non-irradiation image, and obtains a light cutting line by scanning the difference image. The profile shape of the ring material may be measured based on the obtained light cutting line.

  According to the ring material shape measuring method and the measuring apparatus of the present invention, when manufacturing the ring material from the ring-shaped rolled material, the profile shape of the ring material can be obtained in real time without being affected by the scale such as an oxide layer. Can be measured accurately.

It is a schematic diagram which shows the outline of a ring rolling mill. It is sectional drawing which shows the rolling state in a ring rolling mill. It is a figure which shows the image of the outer peripheral surface of a ring material in case the oxide layer has not generate | occur | produced. It is a figure which shows the image of the outer peripheral surface of a ring material in case the oxide layer has generate | occur | produced. It is a figure which shows the shape measuring method of the ring material of this invention. It is a figure which shows the irradiation image with which the slit light was irradiated with respect to the outer peripheral surface of a ring material. It is a figure which shows the non-irradiation image in which slit light is not irradiated with respect to the outer peripheral surface of a ring material. It is a figure which shows the difference image which took the difference of an irradiation image and a non-irradiation image.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a ring material shape measuring method and a shape measuring apparatus according to the present invention will be described with reference to the drawings. In addition, embodiment described below is an example which actualized this invention, Comprising: It is not for limiting the structure of this invention only to the specific example. Therefore, the technical scope of the present invention is not limited only to the disclosed contents of the present embodiment.
Further, in the present embodiment, a description will be given by taking, as an example, a large ring material Z made of pure titanium and titanium alloy used in a fan case of an aircraft jet engine.

As shown in FIGS. 1 and 2, the ring rolling machine 10 used in the shape measuring method of the ring material Z and the shape measuring device of the present embodiment is configured to form a ring-shaped rolled material W (original material) into a predetermined shape. And a ring material Z (rolled product) having an outer diameter (predetermined profile shape).
The ring rolling mill 10 includes a king roll 11 that rotates a ring-shaped rolled material W, a mandrel roll 12 that faces the king roll 11 and reduces the rolled material W in a radially outward direction, and a perfect circle of the rolled material W. A centering roll 13 that holds the rolled material W so as not to move in the horizontal direction while maintaining the degree, and an axial that holds the rolled material W so as not to move in the axial direction (vertical direction) by rolling. The rolls 14A and 14B and axial roll frames 15A and 15B that rotatably support the axial rolls 14A and 14B are configured.

The king roll 11 is rotatably fixed to the outer peripheral surface side of the ring-shaped rolled material W. The king roll 11 is connected to a driving device such as a motor and is driven to rotate. As the king roll 11 rotates, the ring-shaped rolled material W in contact with the king roll 11 rotates.
As shown in FIG. 2, in the case of the present embodiment, the outer shape of the king roll 11 is constituted by a concavo-convex shape (surface cross-sectional profile) having one or more protrusions 11A and depressions 11B. This outer shape has, for example, different shapes (asymmetric in the vertical direction) between the upper side from the center and the lower side from the center with respect to the axis of the king roll 11.

By this vertically asymmetric outer shape, a vertically asymmetric uneven shape is formed on the outer peripheral surface of the ring material Z.
The concave portion ZA formed on the outer peripheral surface of the ring material Z is formed by pushing the protrusion 11A of the king roll 11 and thus is a portion having a high degree of rolling down, that is, a “pressing portion”. On the other hand, the convex part ZA formed on the outer peripheral surface of the ring material Z is a part formed by the reduction of the hollow part 11B of the king roll 11, and is a part having a low degree of reduction, that is, a “non-indented part” ZB.

A black oxide layer X (black skin) adheres to the surface of the ring material Z during or immediately after rolling, but this black skin X is often present in the uncompressed lower portion ZB (convex portion) of the ring material Z. However, the inventors of the present application have found that there is little in the indented portion ZA (concave portion) from the past results of rolling.
The mandrel roll 12 has a cylindrical shape with a smaller diameter than the king roll 11 and is rotatably installed at a position facing the king roll 11 (inner peripheral surface side of the ring-shaped rolled material W), and in the horizontal direction (radial direction). Can be moved to. After the mandrel roll 12 is brought into contact with the inner peripheral surface of the ring-shaped rolled material W, the rolling is performed while rotating with respect to the rolled material W by further moving in the radially outward direction.

As shown in FIG. 1, the centering roll 13 has a cylindrical shape, faces the mandrel roll 12, and is disposed on the outer peripheral surface side of the ring-shaped rolled material W so as to face the mandrel roll 12 and is arranged in a pair of left and right. Has been. The centering roll 13 adjusts the roundness of the ring material Z and suppresses the ring material Z from moving in the horizontal direction.
The axial rolls 14A and 14B have a conical shape, and are supported by the axial roll frames 15A and 15B so as to be rotatable in a pair of upper and lower sides at a position opposite to the king roll 11 in an inclined state. The side surfaces (conical surfaces) of these axial rolls 14A and 14B are in contact with each other so as to sandwich the upper end surface and the lower end surface of the ring-shaped rolled material W.

The axial rolls 14A and 14B that are in contact with the upper and lower end surfaces of the rolled material W are rotated by the rotation of the ring-shaped rolled material W to perform the vertical (height) reduction and the vertical movement of the rolled material W. Is suppressed, and the shape in the height direction is maintained.
Next, when manufacturing the ring material Z from the ring-shaped rolled material W using the ring rolling machine 10 described above, the shape measuring device 1 of the ring material Z that measures the profile shape of the ring material Z in real time, explain.

  As shown in FIG. 2, the shape measuring device 1 is suspended and held from an upper axial roll frame 15 </ b> A that rotatably supports an axial roll 14 </ b> A disposed on the upper side of the ring material Z. The position where the shape measuring device 1 is held may be a position where the entire outer peripheral surface of the ring material Z can be imaged. For example, as shown in FIG.

  This shape measuring apparatus 1 includes an irradiation unit 2A that irradiates the outer peripheral surface of the ring material Z, which is an object to be measured, with the slit light S, and an imaging unit 2B that images the outer peripheral surface of the ring material Z irradiated with the slit light S. Based on the obtained light cutting line L, the light cutting line extraction unit 3 that obtains the light cutting line L by scanning the optical cutting sensor 2 and the image M (imaging range H) imaged by the imaging unit 2B. And a shape measuring unit 4 that measures the profile shape (three-dimensional shape) of the ring material Z based on the principle of the triangulation method.

The irradiation unit 2A of the light cutting sensor 2 is configured to include a laser light emitting element that can irradiate line light that vertically cuts the object to be measured and can irradiate infrared or visible laser light as the line light. .
The imaging unit 2B of the light cutting sensor 2 captures, as an area image, an object to be measured on which the line light from the irradiation unit 2A is irradiated, and is configured by, for example, a CCD area camera.

The light cutting line extraction unit 3 to which the image M imaged by the imaging unit 2B is input and the shape measurement unit 4 that measures the profile shape of the ring material Z are configured by a digital processing device such as a personal computer.
When measuring the profile shape of the ring material Z using this shape measuring device, first,
The ring material Z is irradiated with the slit light S from the irradiation unit 2A, the outer peripheral surface of the ring material Z irradiated with the slit light S is imaged by the imaging unit 2B, and the captured image M is scanned to obtain the light. The cutting line L is obtained by the light cutting line extraction unit 3, and the profile shape of the ring material Z is measured by the shape measuring unit 4 using the light cutting method for the obtained light cutting line L. By using this shape measuring device, the profile shape (x, y, z coordinate value) of the ring material Z can be measured from a remote location without contact.

The present invention has a great feature in the processing method in the optical section line extraction unit 3 described above. Hereinafter, a processing method in the light section line extraction unit 3 will be described.
First, the image M (image M in which line light is reflected) captured by the imaging unit 2B is input to the light section line extraction unit 3. Then, the light section line extraction unit 3 scans the input image M and determines the position with the highest luminance as the light section line L.

However, in the optical section line extraction unit 3 of the present embodiment, “extraction of the optical section line LA in the indented section ZA of the ring material Z” and “extraction of the optical section line LB in the uncompressed section ZB of the ring material Z” are performed. A different approach is used.
First, in the case of extraction of the optical cutting line LA in the indentation ZA of the ring material Z, the image M (imaging range H) corresponding to the indentation ZA of the ring material Z is scanned, and the position with the highest luminance is determined as the ring material Z. Is determined to be the optical section line LA in the indentation ZA. The position of the indentation ZA in the captured image is known in advance from the profile of the king roll 11 or the like.

  On the other hand, in the case of extraction of the optical cutting line LB in the uncompressed lower part ZB of the ring material Z, the position of the optical cutting line LA already determined and the outer shape of the king roll 11 (particularly, the depth of the recess 11B of the roll outer shape) From this, a search region (ROI) for searching for the light section line LB in the uncompressed lower portion ZB is set. Then, the image M (imaging range H) corresponding to the imaged ring material Z corresponding to the uncompressed lower part ZB is scanned, and the position having the highest luminance in the search region is determined as the light cutting line LB in the uncompressed lower part ZB. . The position of the uncompressed lower portion ZB in the captured image M is known in advance from the profile of the king roll 11 or the like.

The shape measuring unit 4 uses a triangulation method principle based on the light cutting line LA in the indentation ZA and the light cutting line LB in the non-indentation ZB extracted by the light cutting line extraction unit 3. The profile shape of Z is measured.
Moreover, the shape measuring apparatus 1 of this invention also has the function shown below.
The imaging unit 2B captures an irradiation image N (imaging range H) in which the slit light S is applied to the outer peripheral surface of the ring material Z, and the slit light S is applied to the outer peripheral surface of the ring material Z. A non-irradiated image O (imaging range H). In addition, since the ring material Z is manufactured by hot rolling after being overheated in a heating furnace, the ring material Z is self-luminous by heat, so that an image M of the outer peripheral surface of the ring material Z is taken. Can do.

The light section line extraction unit 3 obtains a difference image P (imaging range H) obtained by taking the difference between the irradiated image N and the non-irradiated image O, and determines the light section line L by scanning the difference image P. have.
Next, a method for measuring the shape of the ring material Z rolled hot will be described using the above-described measuring device.

First, a rolled material W (such as a titanium alloy) heated to a predetermined temperature (about 600 ° C. to about 1100 ° C.) and processed into a ring shape having a predetermined thickness, inner diameter and outer diameter is subjected to ring rolling. Installed in the machine 10, the king roll 11 is brought into contact with the outer peripheral surface of the rolled material W and the mandrel roll 12 is brought into contact with the inner peripheral surface of the rolled material W.
Then, the king roll 11 is driven to rotate, the rolled material W is rotated, and the mandrel roll 12 is pressed down toward the king roll 11 with respect to the rotating rolled material W. A hot ring that performs rolling while rotating the rolled material W to expand the diameter until it becomes a ring material Z having a target shape and dimensional accuracy (the ring material Z in which the outer shape of the king roll 11 is transferred to the outer peripheral surface). Repeat rolling.

During this hot ring rolling, the shape of the ring material Z (ring-shaped rolled material W) is measured in real time.
Specifically, first, the imaging unit 2B irradiates the outer peripheral surface of the ring material Z with the slit light S from the irradiator, and the image M (imaging image) of the outer peripheral surface of the ring material Z irradiated with the slit light S. The range H) is imaged.

As shown to FIG. 3A, when the black oxide layer X (black skin) has not arisen in the outer peripheral surface of the ring material Z, the optical cutting line L is covered over all the areas (the upper end part from the upper end part of the ring material Z). Can be detected.
On the other hand, as shown in FIG. 3B, when the black oxide layer X is generated on the outer peripheral surface of the ring material Z, the reflected light intensity from the black oxide layer X is reduced, so that many erroneous detections of the light cutting line L are caused. Become. The inventors of the present application have found that the black oxide layer X present on the surface of the ring material Z is present in a large amount in the non-indented portion ZB (convex portion) and is small in the indented portion ZA (concave portion). It is found from the results.

Further, in the case of hot ring rolling, since the ring material Z is at a high temperature and appears to emit light from the ring material Z itself, the light cutting line L may be erroneously detected by the light emission.
Therefore, the light cutting line extraction unit 3 accurately detects the light cutting line L even when the black oxide layer X is generated on the outer peripheral surface of the ring material Z, particularly the uncompressed lower portion ZB.
As shown in FIG. 4, the image M corresponding to the indentation ZA (underlying the high pressure) is scanned, and the position (A) having the highest luminance is determined as the light cutting line LA in the indentation ZA.

Then, a search area for searching for the light cutting line LB in the non-cushion ZB is set from the position of the light cutting line LA obtained from the image M corresponding to the indentation ZA and the outer shape of the king roll 11.
In setting the search area, the height of the protrusion 11A, that is, the depth h of the recess 11B is calculated from the outer shape of the king roll 11.

A search region (ROI) for searching for the optical cutting line LB in the uncompressed lower portion ZB in a range corresponding to the depth h of the hollow portion 11B calculated from the position corresponding to the optical cutting line LA in the uncompressed lower portion ZB (low pressure lower portion). And set.
The image M corresponding to the uncompressed lower portion ZB is scanned, the luminance value is measured, and the position (B) having the highest luminance in the search area is searched. As a result of the search, the maximum luminance value (B) is determined as the light section line LB in the uncompressed lower portion ZB.

As can be seen from FIG. 4, by setting the search region that is a feature of the present invention, the position (B ′) that does not correspond to the non-indented portion ZB is not determined as the light cutting line LB in the non-indented portion ZB. The position (B ′) corresponding to the indented portion ZB can be determined as the light cutting line LB in the non-indented portion ZB.
Then, the profile measuring unit 4 measures the profile shape of the ring material Z based on the principle of the triangulation method based on the light cutting line LA and the light cutting line LB determined by the light cutting line extraction unit 3.

The above-described shape measurement procedure is repeated until the ring material Z has a target shape and dimensional accuracy.
According to the shape measurement technique of the present invention described above, when manufacturing the ring material Z from the ring-shaped rolled material W, the profile shape of the ring material Z can be obtained in real time without being affected by the scale such as the black skin X. It becomes possible to measure accurately.
[Another procedure]
Next, another procedure of the method for measuring the shape of the ring material Z of the present invention (the processing method in the light cutting line extraction unit 3) will be described.

As shown in FIG. 5A, the imaging unit 2B first irradiates the outer circumferential surface of the ring material Z with the slit light S and images the irradiated image N (imaging range H).
As shown in FIG. 5B, the non-irradiated image O (imaging range H) in which the slit light S is not irradiated on the outer peripheral surface of the ring material Z is also captured.
As illustrated in FIG. 5C, the light section line extraction unit 3 obtains a difference image P (imaging range H) obtained by taking a difference between the captured irradiated image N and the non-irradiated image O. The difference image P is scanned to determine the light section line L.

The shape measuring unit 4 measures the profile shape of the ring material Z based on the light cutting line L determined by the light cutting line extraction unit 3.
By obtaining the difference image P obtained by taking the difference between the irradiated image N and the non-irradiated image O, the self-luminous component from the ring material Z can be removed, and the profile shape of the ring material Z can be accurately measured. it can. Further, as a result of removing the self-luminous component of the ring material Z, the threshold value can be set low also for the surface shape near the oxide layer X where the reflected light intensity is low, and the detection accuracy of the light section line L is improved. .

According to the shape measuring method and the shape measuring apparatus 1 of the ring material Z of the present invention, when the ring material Z is manufactured from the ring-shaped rolled material W, the ring material is not affected by the scale such as the oxide layer X. The profile shape of Z can be measured accurately and simply in real time.
Further, by feeding back the measurement result of the profile shape of the ring material Z, stable hot ring rolling can be performed.

Further, by obtaining the difference image P, the erroneous detection due to the black oxide layer X can be further reduced, so that the measurement result of the profile shape of the ring material Z becomes stable.
In addition to the method of “extracting the light cutting line L using the difference image P”, the method of “searching for the light cutting line L after setting a search region in the uncompressed lower part ZB” may be used at the same time. .

  It should be noted that matters not explicitly disclosed in the embodiment disclosed this time, such as operating conditions and measurement conditions, various parameters, dimensions, weights, and volumes of components, deviate from a range that is normally implemented by those skilled in the art. Instead, values that can be easily assumed by those skilled in the art are employed.

DESCRIPTION OF SYMBOLS 1 Shape measuring device 2 Optical cutting sensor 2A Irradiation part 2B Imaging part 3 Optical cutting line extraction part 4 Shape measuring part 10 Ring rolling mill 11 King roll 11A Projection part 11B Depression part 12 Mandrel roll 13 Centering roll 14A Axial roll (upper side)
14B Axial roll (lower side)
15A Axial roll frame (upper side)
15B Axial roll frame (lower side)
S Slit light L Optical cutting line LA Optical cutting line (pressed part)
LB Light cutting line (Uncompressed lower part)
M image N irradiated image O non-irradiated image
P Difference image X Oxide layer (black skin, scale)
W Rolled material Z Ring material ZA Non-pressed part (convex part)
ZB Indentation (recess)

Claims (4)

Using a ring rolling mill having a king roll, a ring material in which an “indented portion” that is a portion that is reduced in the axial direction and a “non-indented portion” that is an unreduced portion is formed on the outer peripheral surface. In the method of measuring the shape of the ring material, the profile shape of the outer peripheral surface of the ring material is measured using a light cutting method when rolled hot.
Irradiate slit light to the outer peripheral surface of the ring material,
Image the outer peripheral surface of the ring material irradiated with the slit light,
By scanning the captured image, an optical cutting line is obtained,
Based on the obtained optical cutting line, the profile shape of the ring material is measured,
When scanning the image corresponding to the indent, the position with the highest brightness is determined as the light cutting line in the indent,
When scanning the image corresponding to the uncompressed portion, the optical cutting line in the uncompressed portion is calculated from the position of the optical cutting line obtained from the image corresponding to the indented portion and the outer shape of the king roll. Set the search area to search for
In the set search region, a position having the highest luminance is determined as a light cutting line in the uncompressed lower part. When measuring the shape of the ring material,
Taking an irradiation image in which slit light is irradiated on the outer peripheral surface of the ring material, and capturing a non-irradiation image in which slit light is not irradiated on the outer peripheral surface of the ring material,
Find the difference image that took the difference between the irradiation image and the non-irradiation image,
By scanning the difference image, an optical cutting line is obtained,
The shape measurement method for a ring material according to claim 1, wherein the profile shape of the ring material is measured based on the obtained light cutting line. Using a ring rolling mill having a king roll, a ring material in which an “indented portion” that is a portion that is reduced in the axial direction and a “non-indented portion” that is an unreduced portion is formed on the outer peripheral surface. When rolling hot, in the ring material shape measuring device for measuring the profile shape of the outer peripheral surface of the ring material using a light cutting method,
An irradiation unit for irradiating slit light to the outer peripheral surface of the ring material;
An imaging unit that images the outer peripheral surface of the ring material irradiated with the slit light;
By scanning the captured image, a light cutting line extraction unit for obtaining a light cutting line;
Based on the obtained optical cutting line, it has a shape measuring unit for measuring the profile shape of the ring material,
The light section line extraction unit includes:
When scanning the image corresponding to the indent, the position with the highest luminance is determined as the light cutting line in the indent, and in scanning the image corresponding to the non-indent, corresponding to the indent From the position of the optical cutting line obtained from the image to be determined and the outer shape of the king roll, a search area for searching the optical cutting line in the uncompressed lower part is set,
In the set search region, the position with the highest luminance is determined as the light cutting line in the uncompressed lower part. The imaging unit captures an irradiation image in which slit light is irradiated on the outer peripheral surface of the ring material, and captures a non-irradiation image in which slit light is not irradiated on the outer peripheral surface of the ring material,
The light cutting line extraction unit obtains a difference image obtained by taking a difference between the irradiated image and the non-irradiated image, and obtains a light cutting line by scanning the difference image.
The said shape measurement part measures the profile shape of the said ring material based on the calculated | required optical cutting line. The shape measurement apparatus of the ring material of Claim 3 characterized by the above-mentioned.