JP2023137838A - Cylindrical surface imaging device - Google Patents

Abstract

To provide a cylindrical surface imaging device that can image the cylindrical surface of a cylindrical product under certain conditions.SOLUTION: A cylindrical surface imaging device (1) integrally includes irradiation means (2) that irradiates an imaging target area on a cylindrical surface (91) with light, a frame portion (4) that supports imaging means (3) at a position above the irradiation means and facing the imaging target area, and is arranged parallel to the axis of the cylindrical product in a state of use, and a pair of spacing holding portions (5) extending from both axial ends of the frame portion to a position in contact with the cylindrical surface to maintain a constant spacing (H1) between the imaging means and the cylindrical surface.SELECTED DRAWING: Figure 2

Description

The present invention relates to a cylindrical surface photographing device for photographing the surface of a cylindrical product, that is, the cylindrical surface.

JP-A-3-295450 (Patent Document 1) discloses a method of photographing a cylindrical inspection object. In this imaging method, a flat reflector is placed on the surface of a cylindrical object to be inspected, surrounding the area to be inspected, and a light source placed diagonally above the axial direction of the object is directed toward the area to be inspected. This is a configuration in which light is irradiated and the inspection target area is photographed by a camera placed facing the light source in the axial direction of the inspection target. The image of the inspection object taken by the camera is subjected to image analysis such as binarization processing by an image processing device to detect the presence of irregularities on the surface of the inspection object, that is, the presence of defective parts. ing.

Japanese Patent Application Publication No. 3-295450

In Patent Document 1, a reflector is placed on the surface of the object to be inspected to increase the amount of light at the periphery of the area to be inspected, thereby displaying the same appearance as a defective area due to insufficient brightness even though the surface is healthy. This is to prevent this from happening.

On the other hand, in order to quantitatively evaluate the inspection object using images taken by a camera, it is necessary to photograph the inspection area under constant conditions every time. To achieve this, it is required that the positional relationship between the light source, photographing means, and inspection object be constant each time, but in the configuration of Patent Document 1, since the positions of the light source and camera are not fixed, Quantitative evaluation is not possible.

The present invention has been made to solve the above problems, and its purpose is to provide a cylindrical surface photographing device capable of photographing the cylindrical surface of a cylindrical product under certain conditions.

A cylindrical surface photographing device according to an aspect of the present invention is a photographing device for photographing a cylindrical surface of a cylindrical product, and includes an irradiation means for irradiating light onto a region to be photographed on the cylindrical surface, and an irradiation means located above the irradiation means and located above the photographing target. A frame part that supports a photographing means at a position facing the area and is arranged parallel to the axis of the cylindrical product in the use state, and a frame part that extends from both ends of the frame part in the axial direction to a position where it abuts the cylindrical surface; and a pair of spacing parts for maintaining a constant spacing between the cylindrical surface and the cylindrical surface.

Preferably, the distal end portions of the pair of spacing portions are constituted by arcuate contact portions having a radius of curvature larger than the radius of curvature of the cylindrical surface.

Preferably, the camera further includes a cylindrical light shielding member that surrounds the space to be photographed by the photographing means and blocks external light. In this case, it is preferable that the pair of spacing parts be constituted by a pair of axially facing parts of the cylindrical light shielding member that face each other along the axial direction.

Further, it is also desirable that an elastic member having elasticity is provided on at least a portion of the lower end portion of the cylindrical light shielding member.

Preferably, the irradiation means includes a pair of light sources fixed to each of the pair of spacing parts.

The cylindrical product is typically a cast iron tube manufactured by die centrifugal casting.

According to the present invention, it is possible to photograph the cylindrical surface of a cylindrical product under certain conditions. As a result, the image taken by the photographing means can be used for quantitative evaluation of each cylindrical product.

1 is a diagram schematically showing a schematic configuration of a cylindrical surface photographing device according to an embodiment of the present invention, and (A) and (B) are side views showing the relationship between the cylindrical surface photographing device and a cylindrical product in an unused state. FIG. 2 is a diagram and a cross-sectional view. 1 is a diagram schematically showing a schematic configuration of a cylindrical surface photographing device according to an embodiment of the present invention, and (A) and (B) are side views showing the relationship between the cylindrical surface photographing device and a cylindrical product in a state of use. and a cross-sectional view. (A) and (B) are a perspective view and a side view showing a specific configuration example of a cylindrical surface photographing device according to an embodiment of the present invention. FIG. 3 is a diagram schematically showing the function of the contact portion of the cylindrical surface photographing device according to the embodiment of the present invention. It is a figure which shows typically the cylindrical surface photography device based on the modification of embodiment of this invention. (A) is a perspective view showing a cast iron pipe manufactured by the mold centrifugal casting method, and FIG. 6 (B) is a part of the casting surface (cylindrical surface) of the cast iron pipe photographed using a normal photographic means. It is a figure which shows the image obtained.

Embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same reference numerals are attached to the same or corresponding parts in the drawings, and the description thereof will not be repeated.

<About the general configuration>
A schematic configuration of a cylindrical surface photographing device 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. The cylindrical surface photographing device 1 is a device for photographing the cylindrical surface of a cylindrical product 90 such as a cast iron pipe. FIG. 1 shows the cylindrical surface photographing device 1 in an unused state, and FIG. 2 shows the cylindrical surface photographing device 1 in a used state. Note that FIG. 1(B) is a cross-sectional view taken along line IB-IB in FIG. 1(A), and FIG. 2(B) is a cross-sectional view taken along line IIB-IIB in FIG. 2(A).

The cylindrical surface photographing device 1 photographs the cylindrical surface 91 of the cylindrical product 90 from above, and acquires an image of a partial region (photographing target region) of the cylindrical surface 91. The arrow A1 in FIGS. 1 and 2 represents a direction parallel to the axis O of the cylindrical product 90, and this direction is also referred to as the "left-right direction." Arrow A2 is a direction perpendicular to the left-right direction, and this direction is also referred to as the "depth direction." The “depth direction” corresponds to the radial direction of the cylindrical product 90. Arrow A3 represents the direction away from the cylindrical product 90, and this direction is referred to as "upward." Moreover, the opposite direction is called "downward." The left-right direction, the depth direction, and the up-down direction of the cylindrical surface photographing device 1 can be rephrased as the x direction, y direction, and z direction, respectively.

The cylindrical surface photographing device 1 according to the present embodiment photographs the cylindrical surface 91 of a cylindrical product 90 placed horizontally on a conveyance means (such as a belt conveyor) in a factory, for example, from vertically above. Therefore, in this embodiment, the up-down direction represents the vertical direction, and the left-right direction and the depth direction correspond to the horizontal direction. The cylindrical surface photographing device 1 may be configured to photograph the cylindrical surface 91 from the side (for example, right sideways), and "above" is not limited to vertically upward.

The cylindrical surface photographing device 1 includes a camera 3 as a photographing means, a light source 2 as an irradiation means that irradiates light onto a region to be photographed (the region surrounded by a broken line in FIG. 1) on a cylindrical surface 91, and a frame that supports the camera 3. 4 and a pair of spacing holding parts 5 are integrally provided. In this embodiment, such an integrated unit is referred to as a photographing unit PU. Note that illustration of the light source 2 is omitted in FIG. 1(B) and FIG. 2(B).

The cylindrical surface photographing device 1 includes, for example, a lifting means 8 connected to the frame portion 4, and the photographing unit PU is moved between the upper retracted position (corresponding to the non-use state) shown in FIG. It is provided so that it can be slid vertically between the working position (corresponding to the operating state) shown in . The elevating means 8 may be realized by, for example, a mechanical control means (not shown), or may be realized by the operator's own hands. That is, the photographing unit PU can be moved between the upper retracted position and the working position by being slid up and down automatically or manually.

The frame portion 4 is a member that supports the camera 3 at a position facing the cylindrical surface 91 (photographing target area). The camera 3 is attached to the frame portion 4 in a position above the light source 2 and facing directly below. The space 30 from the lens of the camera 3 to the photographing target area of the cylindrical surface 91 is referred to as the "photographing target space 30."

The frame portion 4 is arranged parallel to the axis O when viewed from the side of the cylindrical product 90, and is arranged horizontally in this embodiment. Specifically, the frame portion 4 is arranged so as to be orthogonal to an imaginary straight line connecting the axis (axis O) of the cylindrical product 90 and the lens center of the camera 3 when viewed in the direction of the axis O of the cylindrical product 90. ing. The point where the cylindrical surface 91 intersects with this virtual straight line is the circumferential center position 91t of the imaging target area, and in this embodiment, is the uppermost end of the cylindrical surface 91.

The frame portion 4 is formed, for example, in a rectangular shape with long sides in the left-right direction and short sides in the depth direction. The frame portion 4 may be formed, for example, by assembling a plurality of plates or rods into a frame shape, or may be formed from a single flat plate as shown in FIG. 3(A).

The pair of spacing sections 5 each extend downward from both ends of the frame section 4 in the axis O direction (left and right direction). The pair of spacing holding parts 5 are arranged on both the left and right sides of the imaging target space 30, and have equal lengths. As shown in FIGS. 2(A) and 2(B), the lower end portions of the pair of spacing holding portions 5 come into contact with the cylindrical surface 91 in the use state, and function as legs of the photographing unit PU. In this way, the tip portion (the portion including the lower end surface) of each spacing holding portion 5 constitutes a “contact portion 51” that contacts the cylindrical surface 91 in the use state. Thereby, in the use state, the distance H1 between the camera 3 and the cylindrical surface 91 (specifically, the shortest distance between the lens of the camera 3 and the area to be photographed) is maintained constant.

As shown in FIGS. 1(B) and 2(B), the spacer 5 is an imaginary connecting the axis of the cylindrical surface 91 (axis O) and the lens center of the camera 3 when viewed in the direction of the axis O. They extend in the vertical direction (vertical direction in this embodiment) so as to overlap in a straight line. Each of the spacing holding parts 5 may be formed by a rod-like member that is long in the vertical direction, or may be formed by a substantially rectangular plate-like member having a long side in the vertical direction and a short side in the depth direction. good. In either case, it is desirable that the pair of spacing parts 5 have the same shape.

The light source 2 is typically fixed inside each of the pair of spacing sections 5 (on the side of the space to be photographed). That is, the irradiation means provided in the photographing unit PU includes a pair of light sources 2, and the pair of light sources 2 irradiates light onto the photographing target area of the cylindrical surface 91 from both sides of the cylindrical product 90 in the direction of the axis O. It can be installed as follows. It is desirable that each light source 2 be arranged at a position overlapping a virtual straight line connecting the axis of the cylindrical surface 91 (axis O) and the lens center of the camera 3 when viewed in the direction of the axis O.

The heights from the contact portion 51 to the installation position of the light source 2 are equal to each other. As a result, the distance H2 between each light source 2 and the cylindrical surface 91 (specifically, the height from the imaging target area to the light source 2) is maintained constant in the usage state, so the height of the light source 2 can be adjusted. becomes unnecessary. As a result, by using the photographing unit PU, it is possible to photograph the cylindrical surface 91 of the cylindrical product 90 under conditions in which the positional relationship of the light source 2 and camera 3 with respect to the photographing target area is optimized.

It is desirable that the photographing unit PU further includes a cylindrical light shielding member 6 that surrounds the space 30 to be photographed by the camera 3 and blocks external light (shown by imaginary lines in FIGS. 1 and 2). Thereby, the imaging target area of the cylindrical surface 91 can be photographed under constant conditions (same conditions) without being influenced by the surrounding lighting environment and the like.

<Specific configuration example>
FIG. 3(A) is a perspective view showing a specific example of the configuration of the cylindrical surface photographing device 1. FIG. The cylindrical surface photographing device 1 has a substantially rectangular parallelepiped case portion 10 with an open bottom end, and a camera 3 and a pair of light sources 2 are attached to the case portion 10. The case portion 10 is formed of a member (for example, resin, wood, cardboard, etc.) that has light blocking properties and has a certain degree of rigidity. The case portion 10 constitutes the outer shell of the photographing unit PU.

The frame portion 4 and the cylindrical light shielding member 6 described above are realized by the case portion 10. Specifically, the top plate portion 10a of the case portion 10 constitutes the frame portion 4, and the four side surfaces 10b to 10e of the case portion 10 constitute the cylindrical light shielding member 6. The camera 3 is provided at the center of the top plate section 10a of the case section 10. The top plate portion 10a constitutes an upper end light shielding member that covers the upper end opening of the cylindrical light shielding member 6.

A space 30 to be photographed by the camera 3 is surrounded by four side surfaces 10b to 10e of the case portion 10. Out of the four side surfaces 10b to 10e, a pair of side surfaces 10b and 10c that face each other along the axis O direction (hereinafter referred to as "axial facing sections") prevent outside light from entering from both sides in the axis O direction (left and right direction). Intrusion of external light from both sides in the radial direction (depth direction) is blocked by a pair of side surfaces 10d and 10e that are blocked and face each other along the radial direction (hereinafter referred to as "radial facing sections").

In the photographing unit PU shown in FIG. 3(A), the axially facing portions 10b and 10c of the cylindrical light shielding member 6 function as a pair of distance maintaining portions 5. In other words, the pair of spacing holding parts 5 are constituted by the pair of axially facing parts 10b and 10c of the cylindrical light shielding member 6. Therefore, in this embodiment, the spacing section 5 is formed of a flat plate-like section. The two light sources 2 are attached to the inner surfaces of the pair of axial facing portions 10b and 10c, facing each other.

Each light source 2 may be realized by one LED lighting fixture having a length in the depth direction as shown in the figure, or as a form not shown in the figure, a plurality of LED light bulbs arranged in the depth direction. May contain. Note that the light source 2 may also be attached to the inner surfaces of the pair of radial facing portions 10d and 10e so as to face each other.

FIG. 3(B) schematically shows a side view of the cylindrical surface photographing device 1 viewed from one side in the axis O direction. The lower end portions of the axial facing portions 10b and 10c are cut out in an arc shape along the depth direction. That is, when viewed in the direction of the axis O, the contact portion (tip portion) 51 of the spacer 5 is formed in an arc shape. The radius of curvature R2 of the arc of the contact portion 51 is (slightly) larger than the radius of curvature R1 of the cylindrical surface 91. As a result, when the elevating means 8 lowers the photographing unit PU from the upper retracted position to the working position, the upper end portion of the cylindrical product 90 fits into the arc-shaped contact portion 51, so that the photographing unit PU (Case part 10) can be stably placed on cylindrical product 90.

Note that the ratio "R2/R1" of the radius of curvature of the contact portion 51 to the cylindrical surface 91 is greater than 1.0 and less than or equal to 2.0, preferably less than or equal to 1.7. More preferably, it is greater than 1.0 and less than 1.1. This creates gaps between both ends of the contact portion 51 in the lateral direction (in the depth direction of the photographing unit PU) and the cylindrical surface 91, and between the lower ends of the radially facing portions 10d, 10e and the cylindrical surface 91. Since the gaps can be made smaller, it is possible to reduce the intrusion of outside light into the space 30 to be photographed through these gaps.

By photographing the cylindrical surface 91 with the camera 3 mounted on the above-mentioned photographing unit PU, a good image can be obtained even when the cylindrical product 90 is a cast iron pipe manufactured by die centrifugal casting. be able to. This will be explained with reference to FIG. FIG. 6(A) is a perspective view showing the cast iron pipe 100, and FIG. 6(B) is an image obtained by photographing a part of the casting surface (cylindrical surface) of the cast iron pipe 100 using a normal photographing means. It is. Arrow A4 in FIGS. 6(A) and 6(B) indicates the circumferential direction of the cast iron pipe 100.

Since minute irregularities (irregularities due to peening processing) are formed on the inner peripheral surface of the cylindrical mold used in the mold centrifugal casting method, the casting surface of the cast iron pipe 100 manufactured by the mold centrifugal casting method On the (cylindrical surface) 101, as shown in FIG. 6(B), a large number of annular uneven patterns 102 appear in a striped manner. Therefore, when the cylindrical surface 101 of the cast iron pipe 100 is illuminated from only one side in the direction of the axis O, shadows are formed in the concave portions of the uneven pattern 102. Therefore, it is difficult to accurately grasp the condition of the cast surface from the image taken by the photographing means.

In contrast, in the present embodiment, the intrusion of external light is suppressed, and the imaging target area of the cylindrical surface 91 is captured from both sides in the axis O direction (diagonally downward) using a pair of light sources 2 located at the same height. Since the cylindrical surface 91 is photographed from directly above with the camera 3 in the irradiated state, it is possible to prevent shadows from being formed in the concave portions of the concavo-convex pattern 102 as described above. This makes it possible to obtain a good image in which the uneven shape of the cylindrical surface 91 is clearly defined. Therefore, as schematically shown in FIG. 3(B), for example, by image processing the image taken by the camera 3 in the image processing device PC, the quality of the cylindrical surface 91 of the cylindrical product 90 can be quantitatively determined. It becomes possible to evaluate. As a result, the image of the cylindrical surface 91 captured by the camera 3 can be suitably used as an image for machine learning.

Here, the central angle θ of the arc of the contact portion 51 is less than 180 degrees, preferably less than 120 degrees. Further, it is desirable that the photographing unit PU be able to move horizontally along the depth direction while being raised and lowered by the raising and lowering means 8. In this case, as shown in FIG. 4, in the process of lowering the photographing unit PU from the upper retracted position to the working position by the lifting means 8, the center position of the case part 10 (the position of the camera 3) is relatively moved to one side in the depth direction. Even if it is shifted to the left side (on the paper), the opposite end (on the right side on the paper) of the contact portion 51 contacts the cylindrical surface 91a first and descends along the cylindrical surface 91a, so that the position in the use state is Misalignment can be suppressed or prevented. That is, the contact portion 51 functions as a guide member, so that the light source 2 and the camera 3 can be appropriately positioned (centered) with respect to the imaging target area of the cylindrical surface 91.

Therefore, for example, when sequentially photographing cylindrical products 90 that are continuously transported in a factory, etc., even if the position of the cylindrical products 90 is slightly shifted, the images are taken under the same conditions (constant conditions) each time. An image of the cylindrical surface 91 can be acquired.

Note that the radius of curvature R2 (FIG. 3(B)) of the contact portion 51 may be determined so as to be compatible with a plurality of cylindrical products 90 having different diameters. In this case, by setting the radius of curvature R2 to be (slightly) larger than the radius of curvature R1b of the cylindrical surface 91b of the cylindrical product 90 with a relatively large diameter, as shown in FIG. The center portion of the contact portion 51 can also be reliably brought into contact with the cylindrical surface 91a (radius of curvature R1a) of the cylindrical product 90.

However, if it is possible to accommodate a plurality of cylindrical products 90 having different diameters, as shown in FIG. An elastic member 7 having elasticity may be attached. The elastic member 7 is made of a foam such as urethane or sponge, and has light blocking properties. It is desirable that the elastic member 7 extends in the left-right direction over the entire width of the lower end edges of the radial facing portions 10d and 10e. In this case, in the use state, it is possible to more sufficiently suppress the intrusion of external light into the case portion 10, so that the photographing conditions can be improved.

Further, the elastic member 7 may also be provided at the lower end portions (lower end surfaces) of the pair of axially facing portions 10b and 10c (not shown). That is, all or part of the contact portion 51 may be realized by the elastic member 7. In this case, even when the cylindrical surface 91a of the relatively small-diameter cylindrical product 90 is to be photographed, the contact area by the contact portion 51 becomes large, so that the photographing conditions can be further improved.

In this embodiment, an example in which the cylindrical light shielding member 6 has a prismatic shape has been described, but the present invention is not limited to such an example. The cylindrical light shielding member 6 may have a cylindrical shape, for example.

Furthermore, in the present embodiment, the cylindrical light shielding member 6 is realized by the rigid case portion 10, but as shown in FIG. When configured differently, the cylindrical light shielding member 6 does not need to have rigidity. For example, the cylindrical light shielding member 6 may be realized by a flexible cloth suspended from the frame portion 4.

In addition, although an example has been described in which the cylindrical product 90 is a cast iron pipe 100 manufactured by a die centrifugal casting method, cast iron pipes manufactured by other methods and other types of pipe products may also be used for cylindrical surface imaging. The device 1 can be suitably used. Note that when other types of pipe products are targeted, the number and installation positions of the light sources 2 that illuminate the cylindrical surface 91 are not limited to the above example.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

Reference Signs List 1 cylindrical surface photographing device, 2 light source, 3 camera, 4 frame portion, 5 interval holding portion, 6 cylindrical light shielding member, 7 elastic member, 8 elevating means, 10 case portion, 10b, 10c axial facing portion, 10d, 10e radial facing portion, 30 imaging target space, 51 contact portion, 90 cylindrical product, 91, 91a, 91b cylindrical surface, 100 cast iron pipe, 102 uneven pattern, O axis, PU imaging unit.

Claims (6)

A photographing device for photographing the cylindrical surface of a cylindrical product,
irradiation means for irradiating light onto a region to be photographed on the cylindrical surface;
a frame portion that supports a photographing means at a position above the irradiation means and facing the photographing target area, and is arranged parallel to the axis of the cylindrical product in a state of use;
integrally comprising a pair of distance maintaining portions extending from both axial ends of the frame portion to a position abutting the cylindrical surface and maintaining a constant distance between the photographing means and the cylindrical surface; Cylindrical surface imaging device. The cylindrical surface photographing device according to claim 1, wherein the tip portions of the pair of spacing holding portions are constituted by arcuate contact portions having a radius of curvature larger than the radius of curvature of the cylindrical surface. further comprising a cylindrical light shielding member that surrounds the space to be photographed by the photographing means and blocks external light;
The cylindrical surface photographing device according to claim 1 or 2, wherein the pair of spacing holding parts are constituted by a pair of axially facing parts of the cylindrical light shielding member that face each other along the axial direction. The cylindrical surface photographing device according to claim 3, wherein at least a part of the lower end of the cylindrical light shielding member is provided with an elastic member having elasticity. The cylindrical surface photographing device according to any one of claims 1 to 4, wherein the irradiation means includes a pair of light sources fixed to each of the pair of spacing parts. The cylindrical surface photographing device according to any one of claims 1 to 5, wherein the cylindrical product is a cast iron pipe manufactured by a mold centrifugal casting method.