JP2013163197A - Device for measuring inside diameter of die and measurement method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device with which the inside diameter of a bearing part of a die can be measured in a short period of time with high accuracy, and to provide a measurement method using the measuring device.SOLUTION: A device for measuring the inside diameter of a die includes: a table 20 rockable in the peripheral direction of a die 50; a camera 31 for capturing the image of the die 50, held with the table 20, from its side face; a feed mechanism for moving the camera 31 in the radial direction of the die 50; a control means for controlling the rock of the table 20 and the feed mechanism; an image analyzing means for analyzing the image of the die 50 at a predetermined angle, the image being captured with the camera 31, and for detecting the position of the bearing part of the die 50; a radius calculating means for calculating the radius of the bearing part of the die 50 from the position of the bearing part of the die 50 detected by the image analyzing means and the position of the camera in the feed mechanism; and an inside diameter calculating means for calculating the inside diameter of the bearing part of the die 50 from point group data composed of angle data and radius data.

Description

  The present invention relates to an apparatus for measuring an inner diameter of a bearing portion of a die used for manufacturing a pipe, and a measurement method using the apparatus. More specifically, the present invention relates to a measuring apparatus capable of measuring the inner diameter of a bearing portion of a die used in a hot extrusion pipe manufacturing method with high accuracy in a short time and a measuring method using the same.

  The hot extrusion pipe making method typified by the Eugene Sejurune method is a method for producing a seamless pipe by extruding and forming a hollow billet as a material from a gap formed by a die and a mandrel. The hot-extrusion pipe manufacturing method can add a relatively high degree of workability to the hollow billet and is excellent in pipe forming performance, so it is frequently used in the manufacture of seamless steel pipes made of difficult-to-process materials such as high alloys. Yes.

  In general, a die used in such a hot extrusion pipe making method is provided in the order of an approach portion, a bearing portion, and a relief portion from the entry side to the exit side of the material. The approach portion has a smaller inner diameter as it approaches the exit side to guide the hollow billet to the bearing portion, and the bearing portion has a constant inner diameter. The outer diameter of the extruded seamless pipe is mainly determined by the inner diameter of the bearing portion of the die. For this reason, the inner diameter of the bearing portion of the die is appropriately designed according to the outer diameter required for the seamless pipe while taking into account the amount of shrinkage in the process of cooling the seamless pipe extruded in the hot state to room temperature. The

  In the case of producing a seamless pipe using such a die by the hot extrusion pipe making method, the die is repeatedly used (reused) from the viewpoint of suppressing the basic unit of the die. However, if the die is reused for extrusion molding, the die gradually wears out and the inner diameter of the bearing portion increases, or during use the lubrication failure or sudden increase in the extrusion speed occurs suddenly and the bearing portion suddenly increases. The inner diameter may increase. When the inner diameter of the die bearing portion is increased, the outer diameter of the extruded seamless pipe increases and becomes a defective product.

  In order to suppress this manufacturing defect in which the outer diameter of the pipe increases, it is necessary to measure the inner diameter of the bearing portion of the die before the extrusion to confirm the change in the inner diameter of the bearing portion. Usually, the inner diameter of the bearing portion is measured using a caliper. However, since the measurement using the caliper is an operator's manual operation, it takes time and results vary depending on the operator.

  A method of automatically measuring the hole diameter and concentricity of a ferrule for measuring the shape of a component is disclosed in Patent Document 1. In this hole diameter measuring method, the ferrule is rotatably held by pressing the ferrule against the V-shaped block using a belt. The entire hole of this ferrule is captured on a single screen by a CCD camera, and projection processing is performed to obtain the center position of the virtual hole and equally divide the outer periphery of the hole to set a plurality of measurement points. Measure the radius of the hole by finding the boundary point and approximating it to a circle equation.

  Here, the ferrule targeted by the hole diameter measuring method proposed in Patent Document 1 has a hole diameter of about 126 μm, whereas the die used for the hot extrusion pipe manufacturing method, which is the subject of the present application, The inner diameter is in the range of 33.7 to 280.0 mm. For this reason, since the resolution decreases when the bearing portion of the die is captured on one screen, the hole diameter measuring method proposed in Patent Document 1 cannot be directly applied to the inner diameter measurement of the bearing portion of the die.

JP-A-8-128815

  The present invention has been made in view of the situation as described above, and uses a die inner diameter measuring device capable of measuring the inner diameter of a bearing portion of a die used in a hot extrusion pipe manufacturing method with high accuracy in a short time. An object is to provide a measurement method.

The gist of the present invention is as follows:
(1) The die inner diameter measuring device has the following configuration.
a) A table that holds a die that is a material to be measured and is swingable in the circumferential direction of the die b) A camera that captures an image of the die held by the table from its end surface side c) The camera is placed on the table A feed mechanism for moving the die held in the radial direction; d) control means for controlling the swing of the table and the feed mechanism; e) analyzing an image of the die imaged by the camera; Image analysis means for detecting the position of the die f) Radius calculation means for calculating the radius of the bearing portion of the die from the position of the bearing portion of the die detected by the image analysis means and the position of the camera in the feed mechanism g) Data on the angle at which the table is swung when the table is swung and images are taken by the camera at predetermined angles; and An inner diameter for calculating the inner diameter of the bearing portion of the die from point cloud data composed of radius data obtained by using the image analysis means and the radius calculation means based on images taken at every predetermined angle. Calculation means

(2) The die inner diameter measuring apparatus according to (1) further calculates a center position from the point group data, and corrects angle data and radius data constituting the point group data using the center position. The inner diameter calculating means of g) calculates the inner diameter of the bearing portion of the die from the point cloud data processed by the correcting means.

(3) The die inner diameter measuring apparatus according to (1) further includes a replacement unit that replaces radius data that exceeds a predetermined range in the point cloud data, and the inner diameter calculating unit in g) includes: The inner diameter of the bearing portion of the die is calculated from the point cloud data processed by the replacement means.

(4) The die inner diameter measuring apparatus according to the above (1) further calculates a center position from the point group data, and corrects radius data constituting the point group data using the center position. And replacement means for replacing radius data exceeding a predetermined range in the point cloud data, and the inner diameter calculation means in g) is configured to obtain the dice from the point cloud data processed by the correction means and the replacement means. Calculate the inner diameter of the bearing.

(5) Further, the die inner diameter measuring method includes the following configuration.
h) A table that holds a die that is a material to be measured and is swingable in the circumferential direction of the die; a camera that images the die held by the table from its end surface; and An inner diameter measuring device having a feed mechanism for moving in the radial direction of the die to be held is used.
i) a moving step of moving the camera by operating the feed mechanism so that a part of the bearing portion of the die held by the table is within the field of view of the camera; j) the table after the moving step An imaging step of swinging and taking an image with the camera at every predetermined angle k) detecting the position of the bearing portion of the die by analyzing the image taken at the imaging step at every predetermined angle; Radius calculation step of calculating the radius of the bearing portion of the die from the detected position and the position of the camera in the feed mechanism l) Bearing of the die based on the obtained point data including the angle data and the radius data Inner diameter calculation step for calculating the inner diameter of the part

(6) When the inner diameter measurement method of the die according to (5) described above calculates the inner diameter of the bearing portion of the die based on the point cloud data, the center position is calculated from the point cloud data, and the center position is calculated. And correcting the angle data and the radius data of the point group data, and calculating the inner diameter of the bearing portion of the die based on the corrected point group data.

(7) When the inner diameter measurement method of the die according to (5) described above calculates the inner diameter of the bearing portion of the die based on the point cloud data, the radius data exceeding a predetermined range is included in the point cloud data. A replacement process is performed, and the inner diameter of the bearing portion of the die is calculated based on the point group data subjected to the replacement process.

(8) When the inner diameter measurement method of the die according to (5) above calculates the inner diameter of the bearing portion of the die based on the point cloud data, the die of the die is corrected based on the point cloud data subjected to correction processing and replacement processing. An inner diameter of the bearing portion is calculated, a center position is calculated from the point cloud data in the correction process, radius data constituting the point cloud data is corrected using the center position, and the point cloud data is corrected in the replacement process. The radius data exceeding the predetermined range is replaced.

The die inner diameter measuring apparatus and the measuring method using the same according to the present invention have the following remarkable effects.
(1) A feed mechanism that moves the camera in the radial direction of the die along with a table that can be swung in the circumferential direction of the die, so that it can capture images with high resolution and high accuracy, and supports various internal diameters. (2) Since the control means, the image analysis means and the calculation means are provided, the measurement can be saved and the time required for the measurement can be shortened.

It is a schematic diagram explaining the structural example of the die inner diameter measuring apparatus of this invention. It is a figure which shows the reuse method of the die | dye using the die inner diameter measuring method of this invention, The figure (a) is an apparatus state at the time of a measurement start, The figure (b) is an apparatus state at the time of imaging, The figure (c) ) Is an image of a die, FIG. 4D is a binarized image of the image, FIG. 4E is a distance d1 from the table swing center to the camera center, and a distance from the camera center to the bearing portion. It is a figure which shows each relationship with d2. It is a figure which shows the relationship between the rocking | fluctuation angle of a table, and the radius of the bearing part of the die | dye calculated. It is a figure explaining the procedure of a correction process, The figure (a) shows the procedure which calculates a center position, The figure (b) shows the procedure which correct | amends using the calculated center position, respectively. FIG. 8A is a diagram for explaining a replacement process according to the present invention. FIG. 10A shows a case where a plurality of radius data continuously exceed a predetermined range, and FIG. Each case is shown. It is a figure which shows the test result of an Example.

  Hereinafter, a die inner diameter measuring apparatus and a measuring method using the same according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram for explaining a configuration example of a die inner diameter measuring apparatus according to the present invention. In the figure, a die inner diameter measuring device 10 and a die 50 as a material to be measured are shown. The die inner diameter measuring apparatus 10 shown in the figure includes a table 20 that holds a die 50, a head 30, and control means, image analysis means, radius calculation means, and inner diameter calculation means (not shown).

  In the die inner diameter measuring apparatus 10 shown in the figure, a camera 31, a light emission 32, and a half mirror 33 are attached to a head 30. In the head 30 configured as described above, light from the illumination is reflected by the half mirror to irradiate the die 50 and the table 20, and the light reflected by the die 50 and the table 20 is reflected by the camera 31 via the half mirror. Detected. Thus, the camera 31 images the dice 50 from the end face side.

  Further, in the die inner diameter measuring apparatus 10 shown in the figure, the head 30 is mounted on a guide (not shown) that guides the die 50 in the radial direction (see the solid arrow in the figure). A mechanism (not shown) is provided. By such a guide and feed mechanism, the camera 31 mounted on the head 30 can move in the radial direction of the die held on the table 20.

  The table 20 holding the dice 50 can swing in the circumferential direction of the held die 50 (see the arrow indicated by the broken line in the figure), and the die 50 held as the table 20 swings is also included. Swing in the circumferential direction.

  For this reason, if the table 31 is swung while the camera 31 is moved in the radial direction by the feed mechanism and a part of the bearing portion of the die 50 is accommodated in the field of view of the camera 31, the entire circumference of the bearing portion of the die is obtained. Can be divided into a plurality of images. As a result, it is possible to capture an image while ensuring resolution, and to deal with various inner diameters.

  In addition, since the die inner diameter measuring device of the present invention includes the image analysis means, the position of the bearing portion of the die 50 can be detected by analyzing the image captured by the camera 31. From the position of the bearing portion of the die 50 detected by this image analysis means and the position of the camera 31 in the feed mechanism, the radius of the bearing portion of the die 50 can be calculated by the radius calculation means. As described above, the die inner diameter measuring apparatus of the present invention holds the die 50 so as to be swingable in the circumferential direction by the table 20, so that if the table 20 is swung at a predetermined angle, the entire bearing portion of the die is moved. The radius can be calculated by imaging over the circumference. And since the control means which controls the rocking | fluctuation of the table 20 and the movement of the camera 31 is provided, the process which images the bearing part of the die | dye 50 over the perimeter and calculates a radius can be saved.

  In this way, if the radius is calculated by imaging the bearing portion of the die over the entire circumference by swinging the table 20 at every predetermined angle, point cloud data composed of the angle data and the radius data can be obtained. it can. This point cloud data indicates the shape of the bearing portion of the die.

  The die inner diameter measuring apparatus of the present invention includes an inner diameter calculating means for calculating the inner diameter of the bearing portion from the point cloud data composed of the obtained angle data and radius data, and therefore can measure the inner diameter of the bearing portion. .

  As described above, the die inner diameter measuring apparatus according to the present invention includes a feed mechanism that moves the camera 31 in the radial direction of the die 50 together with a table that can swing in the circumferential direction of the die 50. As a result, the inner diameter of the die bearing can be measured with high accuracy. In addition, since the control means, the image analysis means, the radius calculation means, and the inner diameter calculation means are provided, the measurement can be saved and the time required for the measurement can be shortened.

  The die inner diameter measuring apparatus of the present invention further calculates a center position from point cloud data composed of angle data and radius data, and corrects angle data and radius data constituting the point cloud data using the center position. It is preferable to provide correction means (not shown). This simplifies the centering operation to align the position of the table swing center with the center of the die when the die is held on the table, resulting in misalignment between the table swing center and the die center. Even when it is, the inner diameter of the bearing portion of the die can be measured with high accuracy. For this reason, the time required for the centering operation performed before the inner diameter measurement process can be suppressed, and the inner diameter of the bearing portion can be measured efficiently.

  Here, when a die is used for extrusion molding, a scale formed on the surface of a lubricating glass used as a lubricant or a hollow billet may remain attached to the surface of the die. In addition, a wrinkle is formed on the surface of the die by contact or care of the die and the material, and this wrinkle is composed of a cut-out concave portion and a convex portion in which the cut portion is agglomerated and adhered to the surface. Such a convex portion of the ridge is a so-called “kaeri”. When lubricating glass or scale adheres to the surface of the die in this way or burr is generated, the calculated radius changes, and the inner diameter of the bearing portion of the die to be measured also changes.

  However, even if lubricating glass or scale adheres to the surface of the die or burr is produced, the outer diameter of the seamless tube extruded using the die is hardly affected. For this reason, it is important to measure the inner diameter of the bearing portion excluding the influence even if lubricating glass or scale adheres to the surface of the die or burr is generated.

  In order to cope with the problem caused by the lubricating glass, scale, and burr, the die inner diameter measuring device of the present invention further replaces radius data exceeding a predetermined range among point cloud data composed of angle data and radius data. It is preferable to provide replacement means. As a result, when the radius of the bearing portion of the die measured by the lubricating glass, scale, or burr is locally fluctuating, the value is replaced. The inner diameter of the bearing part can be measured.

  In the die inner diameter measuring apparatus of the present invention, the inner diameter calculating means preferably calculates the inner diameter of the bearing portion of the die from the point cloud data processed by the correcting means and the replacing means. As a result, the pre-centering operation can be simplified, and the inner diameter of the bearing portion can be measured with high accuracy by removing the influence of the lubricating glass, scale, and burr.

  The die inner diameter measuring method of the present invention using the die inner diameter measuring apparatus of the present invention as described above will be described with reference to the die reuse method used in the hot extrusion pipe manufacturing method.

  2A and 2B are diagrams showing a die reuse method using the die inner diameter measuring method of the present invention, in which FIG. 2A is a device state at the start of measurement, FIG. 2B is a device state during imaging, (C) is an imaged portion of the die, (d) is an image obtained by binarizing the captured image, (e) is a distance d1 from the table swing center to the camera center, and a bearing from the camera center. It is a figure which shows the relationship with the distance d2 to a part, respectively. In the reuse method (measurement procedure) described with reference to FIG. 1, the die inner diameter measuring apparatus shown in FIG. 1 is used.

  In the die reuse method using the die inner diameter measuring method of the present invention, as shown in FIG. 5A, a die as a material to be measured is made swingable in the circumferential direction and held on a table. As a die, the die used in the hot extrusion pipe making method is water-cooled, and then the surface is cleaned by spraying with a brush or compressed air to remove most of the lubricating glass and scale attached to the surface. Can be used.

  Subsequently, the feed mechanism is operated to move the camera 31 mounted on the head 30 in the radial direction of the die 50, and as shown in FIG. To fit. In this state, the camera 31 captures an image.

  After an image is captured by the camera 31, the table 20 is swung, and an image is captured by the camera 31 for another portion of the bearing portion. In this way, the swinging of the table 20 and the image pickup by the camera 31 are repeated, and the image is picked up over the entire circumference of the bearing portion at every predetermined angle. FIG. 6C is a top view showing the die 50 that is a material to be measured. As shown in FIG. 5C, the imaging is performed by the camera so that the imaging locations 51 are distributed over the entire circumference of the bearing portion. .

  The captured image is analyzed by image analysis means, and the position of the bearing portion of the die is detected. FIG. 4D shows an image 40 obtained by binarizing the captured image with reference to luminance. Since the reflection of light irradiated from the illumination is different between the die 50 and the table 20, the die is black and the table is It turns white. For this reason, the boundary between the black portion and the white portion is the position of the bearing portion of the die, and this position is detected by the image analysis means. Specifically, the camera center position 31a is determined in advance, and the distance d2 between the camera center 31a and the detected position of the bearing portion of the die may be measured (calculated) based on the number of pixels.

  The radius of the bearing portion of the die 50 is calculated from the position of the bearing portion of the die 50 detected by the image analysis means and the position of the camera 31 in the feed mechanism. Specifically, an image was captured by adding a distance d2 from the center 31a of the camera 31 to the position of the bearing portion of the die 50 detected to the distance d1 from the table swing center 20a to the camera center 31a. The radius of the bearing portion of the die 50 at the swing angle of the table 20 can be calculated.

  By performing the process of analyzing the image and calculating the radius in this way for a plurality of images captured at predetermined angles, point cloud data composed of angle data and radius data can be obtained. FIG. 5 (e) shows a distance d1 from the center of table swing to the center of the camera, a distance d2 from the center of the camera to the bearing portion of the die, and a radius (d1 + d2) of the bearing portion of the die calculated from these. It is a schematic diagram which shows the relationship. FIG. 4E is a graph with the horizontal axis representing the table swing angle and the vertical axis representing the distance. As shown in FIG. 4E, the distance from the table swing center 20a to the camera center 31a is constant, and the distance from the camera center 31a to the detected position of the bearing of the die 50 varies.

  The inner diameter of the bearing portion of the die is calculated on the basis of point group data composed of such angle data and radius data. The inner diameter can be calculated, for example, by calculating an average value of the radius of the point cloud data and converting the average value into a diameter.

  Evaluate whether the measured inner diameter of the bearing is within the allowable range. When the inner diameter of the bearing portion is smaller than the lower limit of the allowable range, the inner diameter of the bearing portion is adjusted to be within the allowable range by performing removal processing such as cutting on the die. On the other hand, when the inner diameter of the bearing portion is larger than the upper limit of the allowable range, the inner diameter of the bearing portion is adjusted to be within the allowable range by performing overlay welding on the bearing portion of the die. When the inner diameter of the bearing portion is within the allowable range, the die is again used in the hot extrusion pipe making method without performing removal processing or overlay welding. Here, the allowable range of the inner diameter of the bearing portion can be appropriately set based on the size range required for the seamless pipe to be manufactured and the design size of the bearing portion of the die.

  In the method for measuring the inside diameter of a die according to the present invention, a camera 31 moves a part of the bearing portion of the die 50 using a feed mechanism that moves the camera 31 in the radial direction of the die 50 together with a table that can swing in the circumferential direction of the die 50. Since the image is captured, the image can be captured with a sufficient resolution, and as a result, the inner diameter of the bearing portion of the die 50 can be measured with high accuracy. Moreover, if the control means, the image analysis means, the radius calculation means, and the inner diameter calculation means provided in the die inner diameter measuring apparatus 10 are used, the measurement can be saved and the time required for the measurement can be shortened.

In the die inner diameter measuring method of the present invention, when an image is picked up by the camera 31, a predetermined angle is determined so that the image pickup location is symmetric (point symmetric) with respect to the swing center of the table 20, and based on point cloud data. The diameter is calculated by adding the radius at an angle that is symmetric with respect to the center of oscillation to the radius calculated for the angle at which the inner diameter of the bearing portion of the die is calculated. The inner diameter of the bearing portion is preferably set. Here, the predetermined angle is determined so that the imaging location is symmetric (point symmetric) with respect to the center of oscillation of the table 20. The predetermined angle (°) is θ ₁ , θ ₂ ,. _{When i} is set, it means that | θ _j −θ _2j | = 180 ° is satisfied. However, i is an even number and j is an integer of 1 to i / 2. Further, when an angle is θ _j (°), the angle that is symmetric with respect to the center of oscillation means (θ _j + 180 °).

  In the die inner diameter measuring method of the present invention, since the table 20 holding the die 50 swings, if there is a deviation between the center of the die 50 held and the swing center of the table 20, as shown in FIG. An error occurs in the calculated radius.

  FIG. 3 is a diagram showing a relationship between the swing angle of the table and the calculated radius of the bearing portion of the die. As shown in the figure, if the center of the held die coincides with the swing center of the table and there is no positional deviation, the calculated radius is usually substantially constant. Even with such a die having a substantially constant radius, if there is a deviation between the center of the held die and the rocking center of the table, the radius fluctuates depending on the angle and increases or decreases.

  In order to prevent an error in the measurement result of the inner diameter of the bearing portion due to such a variation in radius, a centering operation for matching the center of the die with the center of rocking of the table is required in advance. However, in the seamless pipe production line, when measuring the inner diameter of a die when reusing the die, it is required to measure the inner diameter of the die in a short time to ensure productivity and simplify the centering operation. It is essential to reduce the amount of time required.

  For this reason, the die inner diameter measuring method of the present invention calculates the center position from the point group data when calculating the inner diameter of the bearing portion of the die based on the point group data, and uses the center position to calculate the radius of the point group data. It is preferable to perform a correction process to correct, and calculate the inner diameter of the bearing portion of the die based on the corrected point cloud data. As a result, an error caused by a deviation between the center of the die and the swing center of the table can be suppressed, and the centering operation performed in advance can be simplified.

  When a predetermined angle is determined so that the imaging location is symmetric (point symmetry) with respect to the swing center of the table 20 when an image is captured by the camera, for example, the center position is calculated from the point cloud data by the following procedure. Then, a correction process for correcting the radius of the point cloud data can be performed using the center position.

  4A and 4B are diagrams for explaining the procedure of the correction process. FIG. 4A shows a procedure for calculating the center position, and FIG. 4B shows a procedure for correcting using the calculated center position. FIG. 4A shows a curve 60 drawn by point cloud data and a table swing center 20a. Since the curve 60 is point cloud data obtained by detecting the position of the bearing portion of the die, the curve 60 has a circular shape as shown in FIG.

The i-th point of such point cloud data is denoted by p _i , its radius is r _i , and the swing angle is θ _i . In the point cloud data, the point having the maximum radius is set to p _max , the radius of the point is set to r _max , the swing angle is set to θ _max, and the point having the minimum radius is set to p _min , Let r _{min be} the radius and θ _min be the rocking angle. In this case, the amount of eccentricity w, which is the distance between the center position C of the curve 60 and the table swing center, is a value calculated by the following equation (1), and the angle of the center position C of the curve 60 with respect to the table swing center is Each can be approximated by θ _max .
w = (r _max −r _min ) / 2 (1)

Here, when the xy coordinates with the table swing center as the origin (0, 0) are set, the coordinates of the point p _i are (r _i cos θ _i , r _i sin θ _i ), and similarly, the center position of the curve 60 The coordinates (x _c , y _c ) of _C can be calculated by the following equations (2) and (3) using the above-described eccentricity w and its angle θ _max .
x _c = w × cos θ _max (2)
y _c = w × sin θ _max (3)

In this way, correction is performed by obtaining the angle and radius with the center position calculated from the point cloud data as the origin. FIG. 5B shows the calculated center position C and the curve 60 drawn by the point cloud data. Set the xy coordinates of the origin table pivot center, as shown in FIG. (B), coordinates (x _i, y _i) of the point p _i in the xy coordinate When, origin at the center position C calculated The coordinates of the point p _i in the x′y ′ coordinates, that is, the coordinates of the corrected point p _i are ((x _i −x _c ), (y _i −y _c )). Therefore, the corrected radius r _i ′ and the angle θ _i ′ with respect to the center position C can be calculated by the following equations (4) and (5).
r _i ′ = ((x _i −x _c ) ² + (y _i −y _c ) ² ) ^1/2 (4)
θ _i ′ = tan ⁻¹ ((y _i −y _c ) / (x _i −x _c )) (5)

  In the die inner diameter measuring method of the present invention, when calculating the inner diameter of the bearing portion of the die based on the point cloud data, the substitution processing is performed to replace the radius data exceeding a predetermined range in the point cloud data. It is preferable to calculate the inner diameter of the bearing portion of the die based on the point cloud data. This is to cope with the problems caused by the above-described lubricating glass, scale, and burr. This replacement process will be described with reference to FIG.

  FIG. 5 is a diagram for explaining the replacement processing of the present invention. FIG. 5A shows a case where a plurality of radius data continuously exceed a predetermined range, and FIG. Each case exceeds a predetermined range. The figure shows the relationship between the angle of the table 20 with respect to the swing center and the calculated radius. When lubricating glass or scale adheres, a plurality of radius data tend to continuously vary as shown in FIG. In the replacement process, radius data exceeding a predetermined range is replaced with a radius that is another point and within the predetermined range. Further, when burr occurs, the radius data of only one point tends to fluctuate as shown in FIG. In the replacement process, radius data that exceeds a predetermined range is replaced with radius data that is another point and within the predetermined range.

The “predetermined range” in the replacement process may be set as appropriate based on a dimensional tolerance range required for a seamless pipe that is extruded using a die. Specifically, ± 0.05 mm can be set as the “predetermined range” on the basis of the design dimension (radius) of the bearing portion of the die. Further, when the predetermined range is exceeded, for example, the latest radius data that was within the predetermined range may be replaced. Specifically, it is confirmed whether the radius data is within a predetermined range. If the radius data is within the range, the value is stored, and if the radius data exceeds the range, the stored value is replaced with the stored value. This process may be performed in order from the radii r ₁ to r _{i of the i} point group data.

  In the die inner diameter measuring method of the present invention, when calculating the inner diameter of the bearing portion of the die based on the point cloud data, the inner diameter of the bearing portion of the die is calculated based on the point cloud data subjected to the correction processing and the replacement processing described above. preferable. By performing the replacement process together with the correction process on the point cloud data, the prior centering operation can be simplified, and the inner diameter of the bearing portion can be measured with high accuracy by removing the influence of the lubricating glass, scale, and burr.

  When taking an image with a camera at every predetermined angle, after the table is swung, the swinging is stopped and the image is taken in a stationary state, and the table is swung without being stopped. A method for imaging in a state is conceivable. However, in the method of taking an image in a stationary state with the swinging stopped, the time required for measurement increases because the table swings and stops repeatedly. For this reason, in the die inner diameter measuring method of the present invention, when the table is swung and an image is taken with a camera at every predetermined angle, the image is picked up without stopping the swinging of the table. Is preferred. Thereby, the time required for measurement can be shortened.

  The die inner diameter measuring method according to the present invention includes a method of calculating a radius by analyzing an image each time an image is captured by a camera (hereinafter, also simply referred to as “the former method”), A method of calculating a radius by analyzing an image once stored after completion of image capturing (hereinafter also simply referred to as “the latter method”) can be considered. Both methods have the same theoretical measurement time. However, when measuring a plurality of dice, the latter method separates imaging and analysis / calculation. For example, after taking an image of one die, the image once saved for that die It is possible to perform processing for capturing an image of another die while calculating and analyzing the above.

  For this reason, the die inner diameter measuring method of the present invention preferably adopts the latter method. Specifically, after the step of swinging the table and capturing an image with a camera at every predetermined angle is completed, It is preferable to start the process of analyzing the image and calculating the radius.

  In the die inner diameter measuring method of the present invention, when images are taken with a camera at predetermined angles by swinging a table, images may be taken continuously with a small interval, and a constant equiangularity may be taken. Images may be taken at intervals. However, if the image capturing interval is too small, the time required for measurement processing and image analysis becomes a problem. On the other hand, if the image capturing interval becomes too large, there is a concern that the measurement accuracy may be lowered. In the die inner diameter measuring method of the present invention, in order to shorten the time required for processing while ensuring high accuracy, it is preferable that the angle interval at which the table is swung and the image is taken by the camera is 1 to 5 °. More preferably, it is set to ˜5 °.

  In order to verify the effect of the die inner diameter measuring apparatus of the present invention and the measuring method using the same, a test was performed to measure the inner diameter of the bearing portion of the die used in the hot extrusion pipe manufacturing method.

[Test method]
In Example 1 of the present invention, the inner diameter of the bearing part of the calibration die having an inner diameter of 50 mm was measured by the procedure described in FIG. 2 using the die inner diameter measuring apparatus shown in FIG. At this time, the camera was picked up at 180 positions every 2 °, and a method of calculating the radius by analyzing the image every time the image was picked up by the camera was adopted.

In the second example of the present invention, a method is employed in which imaging by the camera is performed at 90 positions every 4 °, and after the imaging of a plurality of images by the camera is completed, the temporarily stored images are analyzed to calculate the radius. In addition, after the replacement process was performed on the point cloud data composed of the calculated radius and angle, the correction process was performed according to the procedure described with reference to FIG. The replacement process, radius and confirm that it is the range of 50 ± 0.05 mm, and stores that value in the case which was within the range, the point processing for replacing the stored values in the case of exceeding the range p ₁ We went to order for ~p _90. The other measurement conditions were the same as those of Example 1 of the present invention.

  In Example 3 of the present invention, the inner diameter of the bearing portion was measured for a die having an inner diameter of the bearing portion of 50 mm and being used in the hot extrusion pipe manufacturing method. The other conditions were the same as Example 2 of the present invention.

  In this test, the inner diameter measurement was repeated 10 times. In both the inventive examples 1 to 3, the die plate corresponding to the outer diameter of the die is fixed on the table, and the die plate is held on the table by tightening the outer periphery of the die with the three stoppers provided on the upper part of the die plate. did. Further, a CCD camera was used as the camera, and the resolution was adjusted to 0.01 mm, that is, one pixel in the photographed image was adjusted to 0.01 mm in actual length.

[Test results]
FIG. 6 is a diagram showing test results of the examples. As shown in the figure, in Example 1 of the present invention, the inner diameter was measured without performing the correction process and the replacement process, and the measurement results varied over ± 30 μm. In addition, since a camera is used to capture images at 180 points every 2 ° and each time an image is captured by the camera, the radius is calculated by analyzing the image, so the time required for one measurement is 25 seconds. became.

  On the other hand, in Inventive Example 2, the correction process and the replacement process were performed, and the measurement results were all in the range of ± 30 μm, which was good. Further, in Example 2 of the present invention, imaging by the camera was performed at 90 locations every 4 °, and the number of imaged locations was halved compared to Example 1 of the present invention, but a decrease in measurement accuracy due to the influence could not be confirmed. In addition, the second example of the present invention employs a method of performing imaging with a camera at 90 positions every 4 °, and calculating a radius by analyzing images once stored after completing imaging of a plurality of images with the camera. Therefore, the time required for one measurement was 10 seconds, which was good.

  Here, the measurement results varied in Example 1 of the present invention because the calibration die having no local dimensional variation is the material to be measured, so that when the die is held on the table, the table swing center and the die This is because the position of the center is shifted. For this reason, when the centering operation for confirming the positional deviation between the center of rocking of the table and the center of the die is performed using a micrometer or the like when the die is held on the table, the measurement results can both be ± 30 μm.

  In Example 3 of the present invention, the inner diameter of the bearing portion was measured for a die that was used in the hot extrusion pipe manufacturing method and was worn, and all the measurement results were in the range of ± 30 μm, and were good.

  From these results, it has been clarified that the inner diameter of the die bearing portion can be measured with high accuracy and the measuring time can be shortened by the die inner diameter measuring apparatus and the measuring method using the same.

The die inner diameter measuring apparatus and the measuring method using the same according to the present invention have the following remarkable effects.
(1) A feed mechanism that moves the camera in the radial direction of the die along with a table that can be swung in the circumferential direction of the die, so that it can capture images with high resolution and high accuracy, and supports various internal diameters. (2) Since the control means, the image analysis means and the calculation means are provided, the measurement can be saved and the time required for the measurement can be shortened.

  Therefore, if the die inner diameter measuring device of the present invention and the measuring method using the same are applied to die reuse performed in the manufacture of seamless pipes by the hot extrusion pipe making method, the die management accuracy can be improved. In addition, the processing time can be shortened. For this reason, it can greatly contribute to the reduction of the tool cost by improving the quality of the seamless pipe and reducing the number of dies used.

10: Inner diameter measuring device, 20: Table, 20a: Oscillation center of table,
30: Head, 31: Camera, 31a: Center of camera, 32: Lighting,
33: half mirror, 40: binarized image, 50: dice (material to be measured),
50a: center of the die 51: imaging location 60: curve by point cloud data,
d1: Distance from the center of table swing to the center of the camera,
d2: Distance from the center of the camera to the bearing of the die

Claims (8)

A table that holds a die that is a material to be measured and can swing in the circumferential direction of the die;
A camera that captures images of the dice held by the table from its end surface side;
A feed mechanism for moving the camera in the radial direction of the die held by the table;
Control means for controlling swinging of the table and the feed mechanism;
Image analysis means for analyzing the image of the die imaged by the camera and detecting the position of the bearing portion of the die;
Radius calculating means for calculating the radius of the bearing portion of the die from the position of the bearing portion of the die detected by the image analyzing means and the position of the camera in the feed mechanism;
The image is based on the data of the angle at which the table is swung when the table is swung and an image is captured by the camera at every predetermined angle, and the image is captured at every predetermined angle. A die inner diameter measuring device comprising: an analyzing means and an inner diameter calculating means for calculating an inner diameter of a bearing portion of the die from point cloud data composed of radius data obtained by using the radius calculating means. The die inner diameter measuring apparatus according to claim 1, further comprising: a correction unit that calculates a center position from the point group data, and corrects angle data and radius data constituting the point group data using the center position. Prepared,
The die inner diameter measuring device, wherein the inner diameter calculating means calculates the inner diameter of the bearing portion of the die from the point cloud data processed by the correcting means. The inside diameter measuring device for a die according to claim 1, further comprising replacement means for replacing radius data exceeding a predetermined range in the point cloud data,
The die inner diameter measuring device, wherein the inner diameter calculating means calculates the inner diameter of the bearing portion of the die from the point cloud data processed by the replacing means. The die inner diameter measuring apparatus according to claim 1, further comprising: a correction unit that calculates a center position from the point group data and corrects radius data that constitutes the point group data using the center position; A replacement means for replacing radius data exceeding a predetermined range in the group data is provided,
The die inner diameter measuring device, wherein the inner diameter calculating means calculates the inner diameter of the bearing portion of the die from the point cloud data processed by the correcting means and the replacing means. A table that holds a die that is a material to be measured and is swingable in the circumferential direction of the die, a camera that images the die held by the table from the end surface side, and the camera that is held by the table A method of measuring the inner diameter of a die using an inner diameter measuring device provided with a feed mechanism for moving the die in the radial direction,
A movement step of moving the camera by operating the feed mechanism so that a part of the bearing portion of the die held on the table is within the field of view of the camera;
An imaging step of swinging the table after the moving step and capturing images with the camera at predetermined angles;
At each predetermined angle, the position of the bearing portion of the die is detected by analyzing the image captured in the imaging process, and the position of the bearing portion of the die is detected from the detected position and the position of the camera in the feed mechanism. A radius calculating step for calculating a radius;
A die inner diameter measuring method, comprising: an inner diameter calculating step of calculating an inner diameter of the bearing portion of the die based on the obtained point group data composed of angle data and radius data.   When calculating the inner diameter of the bearing portion of the die based on the point group data, a correction process for calculating the center position from the point group data and correcting the angle data and the radius data of the point group data using the center position 6. The die inner diameter measuring method according to claim 5, wherein the inner diameter of the bearing portion of the die is calculated based on the corrected point cloud data.   When calculating the inner diameter of the bearing portion of the die based on the point group data, a replacement process is performed to replace the radius data exceeding a predetermined range in the point group data, and based on the point group data subjected to the replacement process 6. The die inner diameter measuring method according to claim 5, wherein the inner diameter of the die bearing portion is calculated. When calculating the inner diameter of the bearing portion of the die based on the point group data, the inner diameter of the bearing portion of the die is calculated based on the corrected and replaced point group data,
A center position is calculated from the point cloud data in the correction process, and radius data constituting the point cloud data is corrected using the center position,
6. The die inner diameter measuring method according to claim 5, wherein radius data exceeding a predetermined range is replaced in the point cloud data in the replacement processing.

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