Method for detecting appearance defects of curved surface parts and device for implementing the method

Abstract

The present invention relates to the field of visual inspection of parts appearance, and in particular to a method for detecting appearance defects of curved parts and a device for implementing the method. The method for detecting appearance defects of curved parts is to project light onto the curved surface of the curved part, so that the projected light forms a line of light on the curved surface of the curved part along the circumference of the curved surface, and collect the deformation state of the line of light on at least one side of the line of light. If the line of light is deformed, it is determined that the appearance of the curved part has defects. If the line of light is not deformed, it is determined that the appearance of the curved part has no defects. The deformation state refers to a bending state or a discontinuous state. When projected onto a surface defect (such as a groove, crack or protrusion) of a curved part, it will be seen from one side of the line of light that the line of light appears to be deformed by a broken line or discontinuity, thereby quickly and accurately judging whether the curved part has appearance defects, thereby improving the efficiency of detecting appearance missing parts of the curved part.

Description

Technical Field

[0001] The invention relates to the field of visual inspection of parts appearance, and in particular to a method for inspecting appearance defects of curved surface parts and a device for implementing the method. Background Art

[0002] In recent years, machine vision inspection technology has been widely used in the inspection of product surface quality. This technology obtains images of the surface of the inspected object for analysis and identification, and evaluates the surface quality of the product based on this. It has the advantages of high efficiency and high accuracy.

[0003] In actual production, it is often necessary to perform appearance defect inspection on the outer walls of some curved parts (rods, pipes, etc.). If the machine vision inspection technology can be applied to the appearance defect inspection of curved parts, it will inevitably greatly improve the inspection efficiency of curved parts. It is of great significance in some occasions of mass production of curved parts and when curved parts (such as pipes) need to be inspected over long distances. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting appearance defects of curved surface parts to solve the problem of low efficiency in detecting appearance defects of curved surface parts. At the same time, the purpose of the present invention is also to provide a device for implementing the above method.

[0005] The method for detecting appearance defects of curved surface parts of the present invention adopts the following technical scheme: a method for detecting appearance defects of curved surface parts, which method projects light onto the curved surface of the curved surface part so that the projected light forms a line of light on the curved surface of the curved surface part along the circumference of the curved surface, and collects the deformation state of the line of light on at least one side of the line of light. If the line of light is deformed, it is determined that there is a defect in the appearance of the curved surface part; if the line of light is not deformed, it is determined that there is no defect in the appearance of the curved surface part; the deformation state refers to a bending state or a discontinuous state.

[0006] Beneficial effect: The present invention forms the straight line light by projecting light onto the curved surface of the curved part. When the straight line light is projected on a smooth surface, its presented state will remain in a straight line. When it is projected on the surface defects of the curved part (such as grooves, cracks or protrusions, etc.), when observed from one side of the straight line light, it will be seen that the straight line light appears to be deformed by broken lines or discontinuities, thereby quickly and accurately judging whether the curved part has appearance defects. During detection, it is only necessary to make the curved part move relative to the straight line light along the axial direction, so that the appearance defects of the curved part can be found in the process, thereby improving the efficiency of detecting appearance missing parts of the curved part.

[0007] Furthermore, the said straight line light is provided with at least two, and the adjacent straight line light is arranged at intervals and parallel to each other. At the defect, by comparing the spacing between the straight line light and the defect, the size of the defect in the direction perpendicular to the straight line light is calculated. By setting at least two straight line light and presetting the distance between the straight line light, during the detection process, only the number of straight line light across the defect needs to be compared to know the size of the defect in the direction perpendicular to the straight line light, which can not only find the defect, but also measure the size of the defect, and provide a reference for the subsequent processing of the curved surface parts (processing as qualified, scrapping, repairing, etc.).

[0008] Furthermore, multiple optical markers are projected onto the surface of the curved part. The multiple optical markers are evenly distributed in the axial direction of the object being measured. The size of the defect in the object being measured can be calculated by combining the number of evenly distributed points and the circumference of the circle. The optical marker can be used as a scale to mark the size of the defect in the axial direction of the curved part. Combined with the circumference of the curved part, the size of the defect can be measured while the defect is discovered, providing a reference for the subsequent processing of the curved part (qualified processing, scrapping, repairing, etc.).

[0009] Furthermore, the deformation state of the line of light is collected by an image acquisition device, which is more efficient, more accurate, and has a recording function, which facilitates the realization of unmanned automatic detection on site.

[0010] The curved surface part appearance defect detection device of the present invention adopts the following technical scheme:

[0011] The device for detecting appearance defects of curved surface parts comprises:

[0012] matrix;

[0013] The light projection device is installed on the base body and is used for projecting a line of light onto the curved surface of the curved surface part to be inspected, and the line of light extends along the circumference of the curved surface of the curved surface part.

[0014] Beneficial effect: The curved surface part appearance defect detection device of the present invention includes the substrate and the light projection device, and the light projection device can project a straight line of light onto the curved surface of the detected curved surface part. Therefore, when in use, the relative position with the detected curved surface part is fixed, so that the detection of specific points of the curved surface part can be realized, and the relative movement with the detected curved surface part along the axial direction of the detected curved surface part can realize the full axial detection of the curved surface part.

[0015] Furthermore, the light projection device projects more than two straight-line light beams, and two adjacent straight-line light beams are arranged in a spaced relationship and are parallel to each other; or there are more than two light projection devices corresponding to the same position on the circumference of the curved surface of the curved part, and the straight-line light beams projected by each light projection device are arranged in a spaced relationship and are parallel to each other.

[0016] Furthermore, it also includes a light marking device, which is used to project multiple light markers onto the curved surface of the curved part. The multiple light markers are evenly distributed in the axial direction of the object to be measured. Combined with the number of evenly distributed points and the circumference of the circle, the size of the defect of the object to be measured can be calculated.

[0017] Furthermore, it also includes an image acquisition device, which is used to capture the image at the projection position of the one-word light and the light marker, and there is a set angle between the image acquisition device and the axis of the curved surface part to be inspected.

[0018] Furthermore, it also includes an image acquisition device, which is used to capture the image at the projection position of the straight light ray, and there is a set angle between the image acquisition device and the axis of the curved surface part to be inspected.

[0019] Furthermore, the base is a split, openable and closable annular base, and there are more than two light projection devices distributed along the base. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a schematic diagram of the structure of a device for detecting appearance defects of curved surface parts according to an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 The usage status diagram of the curved surface parts appearance defect detection device in;

[0022] Figure 3 yes Figure 2 A local enlarged view at point A;

[0023] Figure 4 1 is a schematic diagram showing the principle of obtaining the size of the surface defect of a curved surface part in Embodiment 1 of the curved surface part appearance defect detection device of the present invention;

[0024] Figure 5 2 is a schematic diagram of the principle of a second embodiment of a device for detecting appearance defects of curved surface parts according to the present invention;

[0025] Figure 6 It is a structural schematic diagram of Example 3 of the curved surface part appearance defect detection device of the present invention.

[0026] In the figure: 11-base, 111-semicircular ring, 12-light projection device, 13-light marking device, 14-image acquisition device, 15-curved surface part, 16-line light, 17-projection bracket, 18-light marker, 19-marking bracket, 20-camera bracket. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0029] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0030] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0031] Embodiment 1 of the method for detecting appearance defects of curved surface parts:

[0032] This method is designed based on the principle that a straight line (i.e. a straight line formed by light hitting an object) appears as a smooth and complete line on a smooth surface, but will deform (such as forming a broken line, discontinuity, etc.) when passing through defects such as grooves, cracks or protrusions on the smooth surface (such as Figure 4). Specifically, a light projection device is used to project a straight line of light, which is vertically projected onto the curved surface of the inspected curved surface part to form a line of light, which is referred to as a straight line of light 16. The straight line of light 16 can be a solid line or a dotted line. The state of the straight line of light is used to determine whether the curved surface part has appearance defects.

[0033] When inspecting curved parts, the projected light can be visible light. In this case, the image can be captured by human eye observation to determine whether the curved parts have appearance defects. Of course, in addition to visible light, the projected light can also be invisible light. In this case, the image can be captured by corresponding equipment, such as infrared cameras, to determine whether the curved parts have appearance defects. In this embodiment, the light projection device specifically uses a laser transmitter, and the projected light is visible light. The image at the line of light is captured by a camera, thereby providing a basis for determining whether the curved parts have appearance defects. In other embodiments, the line of light can also be formed by a grating projector.

[0034] In order to realize all-round detection of curved surface parts, when implementing the detection process, it is necessary to project the straight line light to the curved surface parts at multiple locations in the circumferential direction of the curved surface parts.

[0035] In order to find the appearance defects of curved parts and also know the size of the appearance defects, in this embodiment, at least two straight light rays are provided, and the adjacent two straight light rays are arranged at intervals and parallel to each other. Here, multiple straight light rays are formed by providing a diffraction plate at the laser emitter. Of course, in other embodiments, multiple straight light rays can also be formed by setting multiple laser emitters. At the defect, by comparing the spacing between the straight light rays and the defect, the size of the defect in the direction perpendicular to the straight light rays is calculated. For example, the distance between two adjacent straight light rays is 1mm. If the two edges of the defect along the direction perpendicular to the straight light rays are respectively located on the adjacent two straight light rays, it can be inferred that the size of the defect in this direction is 1mm. If the defect spans three straight light rays, the corresponding size of the defect can be inferred to be 2mm. When the defect is concave / convex, the depth / height of the defect can also be obtained by stereo geometry conversion.

[0036] According to this method, when only a certain position on the axial direction of the curved part needs to be inspected, the laser emitter and the camera are fixed relative to the curved part, and the straight line of light cast by the laser emitter is projected to the position to be inspected, and then the judgment can be made based on the shape of the straight line of light. When a certain section or all of the axial direction of the curved part needs to be inspected, the laser emitter and the camera are moved relative to the curved part along the axial direction of the curved part (such as by installing the laser emitter and the camera on a pole climbing robot, and the walking of the pole climbing robot drives the two to move relative to the curved part), the camera captures and records the image during the movement, and finally judges whether the curved part has appearance defects based on the image. If there are appearance defects, the specific location of the defect can be judged based on the time when the camera records the image and the relative position before and after.

[0037] Embodiment 2 of the method for detecting appearance defects of curved parts:

[0038] The difference between this embodiment and embodiment 1 of the method for detecting appearance defects of curved parts is that, in this embodiment, in order to be able to find the appearance defects of curved parts and also to know the size of the appearance defects, a light marker is set (it can coexist with multiple straight-line light rays, or only one straight-line light ray can be set, and the light marker replaces the function of setting the straight-line light rays as multiple light rays), the light marker is emitted by a light marking device (specifically, a laser transmitter or a projector can also be used), and there are multiple light markers and they are distributed in a straight line in a direction perpendicular to the straight-line light ray. The distance between the light markers can be preset and the light marker can be compared with the edge of the defect to obtain the size of the defect in the axial direction of the curved part. At the same time, combined with the circumference of the curved part, the size of the defect in the circumferential direction of the curved part can be calculated.

[0039] Embodiment 1 of the device for detecting appearance defects of curved parts:

[0040] like Figure 1 As shown, the curved surface part appearance defect detection device includes a base 11, a light projection device 12, a light marking device 13 and an image acquisition device 14.

[0041] The base 11 is a circular ring base. When the detection device is working, it can be put on the curved surface part 15, with the axis of the curved surface part 15 as the axis. If necessary, the base 11 can be driven by a climbing robot and other devices to move along the axial direction of the curved surface part. In order to facilitate installation during use, the base 11 is set as a split structure. In this embodiment, it is specifically composed of two semicircular rings 111, and the cross-section of each semicircular ring 111 is rectangular. Of course, in other embodiments, the base 11 can also be an integrated structure, in which case it can be suitable for curved surface parts of shorter lengths. When the base 11 adopts a split structure, in addition to the structure composed of the above-mentioned two semicircular rings 111, it can also be composed of more arc rings to facilitate assembly around the curved surface part 15.

[0042] The light projection device 12 is mounted on the base 11, and is used to project a line of light 16 on the curved surface of the curved surface part 15 to be inspected, and the line of light 16 extends along the circumference of the curved surface of the curved surface part 15. In this embodiment, the light projection device 12 specifically adopts a laser emitter, and the line of light 16 is obtained by setting a filter on the laser emitter. There are two light projection devices 12 corresponding to the same position (in other embodiments, only one or more than two can be used according to actual conditions), and the two laser emitters are fixedly mounted on the base 11 through a projection bracket 17. The projection bracket 17 is fixed to one side of the axial direction of the base 11, and the overall outer contour is a rectangular parallelepiped. A gap is split at the upper end, and mounting holes are set up and down at the position where the gap passes. The mounting holes are used to install the light projection device 12. When installing, the light projection device 12 is forced into the corresponding mounting hole, and then it can be automatically positioned under the clamping action of the projection bracket 17. The projection directions of the two positioned light projection devices 12 are both toward and perpendicular to the axis of the base 11. The two light projection devices 12 project a line of light beams spaced apart and parallel to each other, wherein the distance between the two line of light beams 16 is preset. When in use, the size of the defect in the corresponding direction can be calculated by comparing the defect range with the distance between the two line of light beams 16. Figure 2 , 3 As shown, two straight lines with a certain distance (such as 10mm) are formed on the surface of the object. By comparing the distance between the straight lines and the defects, the size of the defects can be calculated.

[0043] The optical marking device 13 is used to project a plurality of optical marking symbols 18 onto the curved surface of the curved part 15. The plurality of optical marking symbols 18 are distributed in a direction perpendicular to the straight line light 16. By comparing the spacing between the optical marking symbols 18 and the defect, the size of the defect in the direction perpendicular to the straight line light 16 can be calculated. At the same time, combined with the circumference of the curved part, the size of the defect in the circumferential direction of the curved part can be calculated (e.g. Figure 4). In the present embodiment, the optical marking device 13 also uses a laser emitter, and the optical marker 18 is specifically a light spot, which is formed by configuring a filter on the laser emitter. The optical marking device 13 is installed on the base 11 through a marking bracket 19, and is located on the same side of the base 11 as the light projection device 12. The structure of the marking bracket 19 is similar to the projection bracket 17. The difference is that only one mounting hole is provided on the marking bracket 19 for installing the optical marking device 13. The projection direction of the optical marking device 13 is toward the axis of the base 11. In the present embodiment, there are multiple optical marking devices 13, which are arranged to match the light projection device 12. Specifically, corresponding optical marking devices 13 are configured on both sides of each light projection device 12. As shown Figure 2-3 As shown in the figure, it is assumed that the optical marking device projects 11 optical markers (light spots) on the curved surface part. Through distance control, the spacing between the 11 optical markers after being projected onto the curved surface part is 1 mm. By reading the optical markers projected outside the defect area, the upper and lower sizes of the defect can be obtained, as shown in Figure 2-3 , it can be obtained that the upper and lower distances of the defect are 8mm.

[0044] The image acquisition device 14 is used to capture the image at the projection position of the one-word light 16 and the light marker 18. In this embodiment, the image acquisition device 14 specifically adopts a camera. The camera is installed on the base 11 through a camera bracket 20, corresponding to the light projection device 12 one by one, and is located directly below the light projection device 12, on the side opposite to it. The shooting angle of the camera forms a set angle with the axis of the curved surface part to be inspected. In this embodiment, the structure is manifested as the camera is oriented obliquely upward. In other embodiments, the camera can also be set above the projection point of the light projection device, obliquely downward, or cameras can be set above and below the projection point of the light projection device to better capture the image. Of course, when the light projected by the light projection device is visible light, the image acquisition device can be omitted, and the defects can be observed by human eyes.

[0045] The curved surface part appearance defect detection device includes the substrate, the light projection device, the light marking device and the image acquisition device, and the light projection device can project a line of light on the curved surface of the detected curved surface part, the light marking device can measure the size of the defect area using the principle of a scale, and the image acquisition device can capture and store the detection image. When in use, the relative position with the detected curved surface part is fixed, so that the detection of specific points of the curved surface part can be realized, and the relative movement with the detected curved surface part along the axial direction of the detected curved surface part can realize the full detection of the curved surface part in the axial direction.

[0046] Embodiment 2 of the device for detecting appearance defects of curved parts:

[0047] like Figure 5As shown, the difference between this embodiment and embodiment 1 is that, in this embodiment, the optical marking device is omitted. In this case, the size of the defect can be estimated only by a line of light 16.

[0048] Embodiment 3 of the device for detecting appearance defects of curved parts:

[0049] like Figure 6 As shown, the difference between this embodiment and embodiment 1 is that, in this embodiment, the image acquisition device 14 is arranged above the line of light and is located on one side of the corresponding light projection device.

[0050] In the embodiment 1 of the device for detecting appearance defects of curved surface parts, only one light projection device can be provided at each position, and the size of the defect can be estimated only by the light marking device; or when the light marking device is omitted, only one light projection device can be provided. In this case, the device is only used to detect whether the curved surface parts have defects, and the size of the defect is not measured. The formation of multiple straight-line light rays can also be achieved by a grating projector, or by configuring a filter for a light projection device and utilizing light diffraction.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.

Claims

1. A method for detecting appearance defects of curved surface parts, the method using a curved surface part appearance defect detection device installed on a climbing robot, characterized in that: The device comprises: The base body is a split, openable and closable annular base body; the pole climbing robot drives the base body to move along the axial direction of the curved surface part; A light projection device, wherein there are two or more light projection devices, which are installed on the substrate and distributed along the substrate, and are used to project a line of light onto the curved surface of the curved surface part to be inspected, and the line of light extends along the circumference of the curved surface of the curved surface part; The light projection device projects more than two straight lines of light, and two adjacent straight lines of light are arranged at intervals and parallel to each other; or there are more than two light projection devices corresponding to the same position of the curved surface circumference of the curved surface part, and the straight lines of light projected by each light projection device are arranged at intervals and parallel to each other; a light marking device is used to project multiple light marking symbols onto the curved surface of the curved surface part, and the multiple light marking symbols are evenly distributed in the axial direction of the object to be measured, and the size of the defect of the object to be measured is calculated by combining the number of evenly distributed points and the circumference of the circle; the light marking device is installed on the substrate and is located on the same side of the substrate as the light projection device, and the projection direction of the light marking device is toward the axis of the substrate. There are multiple light marking devices, which are arranged to match the light projection device, and corresponding light marking devices are configured on both sides of each light projection device; An image acquisition device is used to capture the image at the projection position of the line light and the image at the projection position of the light marker. The image acquisition device is installed on the base, corresponds to the light projection device one by one, and is located directly below the light projection device. The method is to project light on the curved surface of the curved part, so that the projected light forms a line light on the curved surface of the curved part along the circumference of the curved surface, and collect the deformation state of the line light on at least one side of the line light. If the line light is deformed, it is determined that there is a defect in the appearance of the curved part. If the line light is not deformed, it is determined that there is no defect in the appearance of the curved part. The deformation state refers to a bending state or a discontinuous state. There are at least two straight-line light beams, and two adjacent straight-line light beams are arranged at intervals and parallel to each other. At the defect, by comparing the spacing between the straight-line light beams and the defect, the size of the defect in the direction perpendicular to the straight-line light beams can be inferred; Multiple light markers are projected onto the curved surface of the curved part. The multiple light markers are distributed in a straight line in a direction perpendicular to the straight line. The multiple light markers are evenly distributed in the axial direction of the object being measured. By comparing the spacing between the light markers and the defects, the size of the defects in the direction perpendicular to the straight line is calculated. At the same time, combined with the circumference of the curved part, the size of the defects in the circumferential direction of the curved part is calculated.

2. A method for detecting appearance defects of curved surface parts according to claim 1, characterized in that: There is a set angle between the image acquisition device and the axis of the curved surface part to be inspected.

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