A non-rotating 360° quality inspection device and inspection method for the inner wall of a hole

Abstract

The present invention discloses a non-rotating 360° quality inspection device and inspection method for the inner wall of a hole. The inspection device includes an image acquisition head. The image acquisition head includes a camera, a liquid lens I, a lens I, a semi-reflective semi-transmissive lens, a liquid lens II, a lens II, a conical reflector, and a point light source. The camera, the liquid lens I, the lens I, the semi-reflective semi-transmissive lens, the liquid lens II, the lens II, and the conical reflector are arranged in sequence from top to bottom. The liquid lens I and the lens I form a lens group I, and the liquid lens II and the lens II form a lens group II. The point light source is arranged on the side of the semi-reflective semi-transmissive lens. The inclination angle of the conical reflector is 45°, and it has a flared shape with a smaller upper part and a larger lower part. The light emitted by the point light source is reflected downward by the semi-reflective semi-transmissive lens, and after passing through the lens group II, it is reflected by the conical reflector to achieve illumination of the inner wall of the hole. The present invention can achieve a comprehensive inspection of the entire axial 360° of the inner wall of the hole, is suitable for holes with different apertures, and is suitable for the inspection of both blind holes and through holes.

Description

Technical Field

[0001] The present invention relates to a non-rotating 360° quality inspection device and inspection method for the inner wall of a hole, belonging to the technical field of inner wall quality inspection of holes. Background Art

[0002] In aerospace equipment and nuclear equipment, the quality requirements for components have reached an almost stringent level, and it is strictly prohibited for components with quality problems to be used in equipment. Screws and screw holes are the most common and essential parts in any equipment, and are also widely used in aerospace equipment and nuclear equipment. Aerospace equipment and nuclear equipment strictly control the quality of any fastening parts such as screws and screw holes, and do not allow any defects, including cracks in materials, thread integrity, surface integrity, burrs, voids, inclusions, etc. Therefore, in order to ensure the safety and reliability of aerospace equipment and nuclear equipment, any pair of screws and screw holes installed in the equipment must be inspected for defects. A more stringent requirement is that during the installation process of aerospace equipment and nuclear equipment, it is also necessary to inspect the quality of the installed screw holes and screws online.

[0003] Currently, the quality inspection of internal threads is mostly completed through downward-looking image shooting, and the inspection range is limited. For example, the patent application with the application number CN201510428037.9 discloses a method for inspecting the quality of a threaded hole structure. Through downward-looking image shooting, it is impossible to well inspect the lower half of the thread, there is a certain angular occlusion, and 360° shooting cannot be achieved. Therefore, in combination with the fine inspection requirements put forward by customers, the present invention proposes a non-rotating 360° quality inspection device and inspection method for the inner wall of a hole that can comprehensively inspect and is suitable for different hole diameters and different hole types. Summary of the Invention

[0004] The present invention provides a non-rotating 360° quality inspection device and inspection method for the inner wall of a hole, which can achieve a comprehensive inspection of 360° of the entire axial direction of the inner wall of the hole, is suitable for holes with different diameters, and is suitable for the inspection of both blind holes and through holes.

[0005] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] A non-rotating 360° quality inspection device for the inner wall of a hole includes an image acquisition head; the image acquisition head includes a camera, a liquid lens I, a lens I, a semi-reflective semi-transmissive lens, a liquid lens II, a lens II, a conical reflector, and a point light source;

[0007] The camera, the liquid lens I, the lens I, the semi-reflective semi-transmissive lens, the liquid lens II, the lens II, and the conical reflector are arranged in sequence from top to bottom; the liquid lens I and the lens I form a lens group I, and the liquid lens II and the lens II form a lens group II;

[0008] The point light source is arranged on the side of the semi-reflective and semi-transmissive lens; the conical reflector has an inclination angle of 45° and is in the shape of a flared trumpet with a smaller upper part and a larger lower part; the light emitted from the point light source is reflected downward by the semi-reflective and semi-transmissive lens, and after passing through the second lens group, it forms approximately parallel illumination light, and then is reflected by the conical reflector with an inclination angle of 45°, forming 360° radial illumination light to achieve 360° illumination of the inner wall of the hole.

[0009] This application is suitable for the detection of the inner walls of various "holes", including through holes, blind holes and other various holes, which can be threaded holes or smooth wall holes, etc.

[0010] The "non-rotating 360° quality inspection device for the inner wall of the hole" in this application means that during detection, without rotation, the quality inspection of the inner wall of the hole along the circumferential direction of 360 degrees can be achieved. "°" is the angle unit "degree".

[0011] The conical reflector, that is, in the shape of a cone, completes the reflection through the outer conical surface.

[0012] Since a comprehensive inspection of the inner wall of the hole is required, the method of taking pictures into the hole from above cannot be used.

[0013] In the above device, with the semi-reflective and semi-transmissive lens as the dividing line, there is a first lens group above the semi-reflective and semi-transmissive lens and a second lens group below the semi-reflective and semi-transmissive lens. The point light source forms approximately parallel coaxial illumination light traveling downward through the semi-reflective and semi-transmissive lens and the second lens group. It should be noted that here, the requirement for the parallelism of the illumination light source is not strict, as long as downward illumination can be achieved. Then, through the reflection of the conical reflector with an inclination angle of 45°, 360° radial illumination light is formed to achieve 360° illumination of the inner wall of the hole.

[0014] In order to improve the applicability of the detection, for example, it is necessary to be able to perform imaging detection on the inner walls of holes with different diameters. The above device also includes a working distance adjustment column, and the length of the working distance adjustment column can be adjusted, such as by using an axially telescopic structure to achieve the adjustment. The two ends of the length of the working distance adjustment column are respectively connected to the second lens and the conical reflector; through the coarse adjustment of the working distance adjustment column and the fine adjustment of the first liquid lens and the second liquid lens, clear imaging is achieved.

[0015] A working distance adjustment column for adjusting the working distance is arranged between the second lens and the conical reflector with an inclination angle of 45° to meet the needs of detecting the inner walls of holes with different diameters. By adjusting the length (height) of different working distance adjustment columns, imaging of the inner walls of holes with different diameters is achieved. Under extreme conditions, the axial height of the working distance adjustment column can also be reduced to zero, that is, without adding or canceling the cylinder, and directly gluing the conical reflector with an inclination angle of 45° to the second lens.

[0016] For holes with a relatively large diameter (e.g., ≥1 cm), the image acquisition head can be inserted arbitrarily into the interior of the hole, and the head of the image acquisition head (the end with the conical reflector) can reach any depth inside the hole; for holes with a relatively small diameter (e.g., <1 cm), usually only the working distance adjustment column with a very small diameter and the conical reflector at its end can be inserted into the hole. Adjust the length of the working distance adjustment column until the conical reflector can reach any depth inside the hole. Therefore, the larger the diameter of the hole, the shorter the length of the required working distance adjustment column; the smaller the diameter of the hole, the longer and thinner the required working distance adjustment column.

[0017] In the present application, for the working distance adjustment column, working distance adjustment columns with different lengths can be processed respectively for holes with different diameters; it can also be designed as a screw and nut structure, with the conical reflector installed on the nut, and the effective length of the working distance adjustment column can be adjusted by rotating the nut; of course, for the axially telescopic structure of the working distance adjustment column, the telescopic structure in the prior art can also be adopted, such as a micro electric telescopic rod.

[0018] In order to more conveniently achieve clear imaging of the inner wall of holes with different diameters in the present application, a liquid lens one is provided between the camera and the lens one, and a liquid lens two is provided between the semi-transmissive semi-reflective lens and the lens two to achieve fine-tuning focusing imaging during imaging. Only when the object-image relationship is satisfied can a clear image be captured. By adjusting the axial length of the working distance adjustment column, only the corresponding relationship between a rough object distance and image distance can be adjusted approximately. To achieve clear imaging of the inner wall of the hole, it is also necessary to adjust the liquid lens one and the liquid lens two to achieve fine adjustment of the imaging, so as to obtain clear imaging.

[0019] Through the coarse adjustment of the working distance adjustment column and the fine adjustment of the liquid lens in the present application, very clear imaging can be achieved, effectively ensuring the accuracy and efficiency of detection.

[0020] For the convenience of detection, the above-mentioned camera, liquid lens one, lens one, semi-transmissive semi-reflective lens, liquid lens two, lens two, working distance adjustment column, conical reflector and point light source are all assembled on the same housing to form an integrated image acquisition head. That is, the image acquisition head of the present application has an integrated design structure, which is convenient for use.

[0021] For the convenience of detection, the above-mentioned device further includes a horizontal machine table, a Z-direction column, a Z-axis and a connecting cross beam; the Z-direction column is vertically arranged on the horizontal machine table, and the Z-axis is installed on the Z-direction column; one end of the connecting cross beam is installed on the Z-axis and can linearly move along the Z-axis, that is, the cross beam can move up and down along the Z-axis (Z direction), and the other end of the connecting cross beam is connected to the image acquisition head, with the camera on the image acquisition head on the top and the conical reflector on the bottom. The above-mentioned cross beam can move up and down along the Z-axis to achieve scanning detection of the entire axial direction of the inner wall of the hole. The present application is suitable for detecting the inner wall of holes at any depth (axial height).

[0022] As a specific implementation solution, the connecting crossbeam is installed on the Z-axis through a slider. The slider can be driven by a lead screw to move up and down, thereby driving the connecting crossbeam and the image acquisition head to move up and down. It can also be that a linear motor drives the slider to move up and down, thereby driving the connecting crossbeam and the image acquisition head to move up and down. At the same time, an existing electronically controlled automation structure can be used to achieve automatic control.

[0023] As another implementation solution, in some cases, the up and down movement of the connecting crossbeam on the Z-axis can also be manually adjusted. For example, the connecting crossbeam can be connected to the Z-axis through a clamp and bolts. When the height needs to be adjusted, only the bolts need to be loosened and reinstalled at a new position to adjust the height of the connecting crossbeam, that is, to adjust the height of the image acquisition head.

[0024] The horizontal machine table is used to place or clamp the workpiece to be inspected.

[0025] To further improve the accuracy of detection, an XY moving platform is provided on the above-mentioned horizontal machine table. A fixture for installing the workpiece to be measured is provided on the XY moving platform, and the X-direction and Y-direction positions of the fixture on the XY moving platform are adjustable. The XY movement can drive the workpiece to be measured to perform a horizontal movement within a certain range to ensure the coaxiality between the hole to be measured and the image acquisition head, and achieve clear imaging of 360°.

[0026] To improve the accuracy of Z-axis adjustment, a scale value is provided on the Z-axis.

[0027] The camera used in this application is a CCD camera or a CMOS camera.

[0028] When used for on-line detection, some fixed brackets and adjustment frames can be added to make it suitable for on-line detection at the installation site.

[0029] Using the above non-rotating 360° quality inspection device for the inner wall of the hole, the method for inspecting the quality of the inner wall of the hole is as follows:

[0030] 1) Insert the head of the image acquisition head into the hole to be measured of the workpiece to be measured. The light emitted from the point light source is reflected downward through the semi-reflective semi-transmissive lens and is collimated by the second lens group to form a downward-traveling approximately parallel coaxial illumination light.

[0031] 2) The approximately parallel illumination light emerging from the second lens group is reflected by a conical mirror with a 45° inclination angle, and further becomes light that irradiates horizontally in all directions, illuminating the inner wall of the hole from an almost perpendicular angle, providing a light field illumination with a certain brightness for subsequent imaging.

[0032] 3) The light reflected and scattered by the illuminated inner wall surface of the hole is reflected by a conical mirror with a 45° inclination angle and enters the second lens group. Then, after passing through a semi-transparent and semi-reflective lens and the first lens group in sequence, without rotation, the inner wall of the hole is imaged on the image plane where the camera image sensor is located, obtaining a 360-degree image of the inner wall of the hole. By analyzing the obtained image of the inner wall of the hole, the quality inspection of the inner wall of the hole is realized.

[0033] In step 3), the analysis of the image can be directly observed by the naked eye or analyzed by existing software. This application has no special improvement on the specific method of software analysis. Therefore, it will not be elaborated here.

[0034] The head of the image acquisition head refers to the end of the image acquisition head where the conical mirror is provided.

[0035] Before detection, the workpiece to be measured is clamped on the fixture of the XY moving platform. The head of the image acquisition head is inserted into the hole to be measured of the workpiece to be measured. The length of the working distance adjustment column shaft is adjusted to obtain a rough correspondence between the object distance and the image distance so as to obtain an image of the inner wall of the hole. Then, the first liquid lens and the second liquid lens are adjusted to make the image clear (here, since the hole to be measured and the image acquisition head are not coaxial, it is impossible to ensure clear imaging at 360°. Here, it is adjusted to be easy to observe to ensure that the coaxiality can be adjusted smoothly and accurately). Then, by adjusting the horizontal position of the fixture on the XY moving platform, the coaxiality between the hole to be measured and the image acquisition head is ensured.

[0036] The coaxiality between the hole to be measured and the image acquisition head is judged by the imaging clarity at different 360° angles of the inner wall of the hole: If it is found that it is clearer at some angles and blurrier at some angles, that is, when the imaging clarity at different angles of the image of the inner wall of the hole obtained in step 3) is inconsistent, it means that the central axis of the hole to be measured does not coincide with the central axis of the image acquisition head. At this time, the XY moving platform needs to be adjusted to adjust the position of the hole to be measured until the imaging clarity at each angle of the inner wall of the hole is consistent, indicating that the central axis of the hole to be measured coincides with the central axis of the image acquisition head, meeting the condition for further adjusting the liquid lens to achieve clear imaging at 360°.

[0037] If the central axis of the hole to be measured does not coincide with the central axis of the image acquisition head, then no matter how the axial length of the working distance adjustment column and the liquid lens are adjusted, since the distances (i.e., object distances) between each angle of the inner wall of the hole and the conical mirror are not equal at this time, it is impossible to ensure clear imaging of the inner wall of the hole at 360° no matter how the liquid lens is adjusted. Therefore, the coaxiality between the hole to be measured and the image acquisition head is a prerequisite for achieving clear imaging of the inner wall of the hole at 360°.

[0038] The above imaging clarity can be observed by the naked eye or read by computer calculation using existing technologies. This application has no special improvement on the specific method of computer reading. Therefore, it will not be elaborated here.

[0039] The axial direction (or central axis) of the test hole in this application is consistent with the Z-axis direction. The axial direction (or central axis) of the image acquisition head is also the optical axes of the conical mirror, the first lens, and the second lens (the optical axes of the three coincide).

[0040] After the test hole and the image acquisition head are coaxially aligned, the first liquid lens and the second liquid lens are adjusted again to obtain a clear image with consistent clarity of the inner wall of the hole at 360°. Then, by moving the cross beam up and down along the Z-axis, the entire axial scan and shooting detection of the inner wall of the hole are realized. Assume that an inner wall image of height h of the hole is extracted from each image, and it is controlled that an image is taken every time the cross beam moves a height h along the Z-axis.

[0041] To improve the detection efficiency, when detecting the inner wall of a hole, the inner wall image of height h extracted from each image is transformed from polar coordinates to Cartesian coordinates, so that the circular inner wall image of the hole is flattened into a planar image; then the planar images of each height h are sequentially stitched together to form a complete two-dimensional planar image (the entire axial direction of the hole), and the quality of the inner wall of the hole is detected by analyzing the complete two-dimensional planar image.

[0042] For technologies not mentioned in this invention, refer to the prior art.

[0043] The non-rotating 360° quality detection device for the inner wall of the hole in this invention integrates the illumination and imaging lenses, which facilitates use; makes full use of the entire field of view, has a wide imaging range, and uses the outer edge of the field of view for imaging, with clear images and high resolution; both illumination and imaging use the lens in the lower part of the semi-reflective and semi-transmissive lens, and a liquid lens is designed therein, which can instantaneously adjust the illumination and imaging effects; in the imaging optical path, a liquid lens is designed in the optical path of the upper part of the semi-reflective and semi-transmissive lens, which can further adjust the imaging clarity; an XY moving platform is further designed, which can adjust the coaxiality between the test hole and the image acquisition head; this invention can achieve a comprehensive 360° detection of the entire axial direction of the inner wall of the hole "without rotation", is suitable for holes with different apertures, and is suitable for the detection of both blind holes and through holes. Description of the Drawings

[0044] Figure 1 It is a cross-sectional view of the internal thread in a blind hole;

[0045] Figure 2 It is a three-dimensional view of the cross-section of the internal thread in a blind hole;

[0046] Figure 3 It is a schematic diagram of the principle of the non-rotating 360° quality detection device for the inner wall of the hole (image acquisition head);

[0047] Figure 4 It is a schematic diagram of the detection state of the non-rotating 360° quality detection device for the inner wall of the hole;

[0048] Figure 5 It is the imaging effect diagram of the internal thread taken in Example 2;

[0049] Figure 6 It is the schematic diagram of the unfolding and splicing of the internal thread image taken in Example 2.

[0050] Figure 7 It is the defective internal thread image taken in Example 2;

[0051] In the figure, 1 is the image acquisition head, 11 is the camera, 12 is the first lens group, 121 is the first liquid lens, 122 is the first lens, 13 is the semi-reflective and semi-transmissive lens, 14 is the second lens group, 141 is the second liquid lens, 142 is the second lens, 15 is the conical reflector, 16 is the point light source, 17 is the working distance adjustment column, 2 is the horizontal machine table, 3 is the Z-axis column, 4 is the connecting cross beam, 5 is the workpiece to be measured, 6 is the XY moving platform, and 7 is the Z-axis. Specific implementation manners

[0052] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments only.

[0053] For the orientation terms such as up and down, left and right, horizontal, and vertical in this application, they are all based on the relative orientation or positional relationship shown in the drawings and should not be construed as an absolute limitation to this application.

[0054] Example 1

[0055] As Figure 3 shown, a non-rotating 360° quality inspection device for the inner wall of a hole includes an image acquisition head; the image acquisition head includes a camera, a first liquid lens, a first lens, a semi-reflective and semi-transmissive lens, a second liquid lens, a second lens, a working distance adjustment column, a conical reflector, and a point light source. The first liquid lens and the second liquid lens are liquid lenses of model Optotune EL-12-30-TC from Optotune Corporation. The first lens and the second lens are imaging lenses of model HL-469 from Gaoguang Company. The interval between each optical element is about 3 mm, and it can be finely adjusted by changing the thickness of the spacer according to the specific project requirements. The spacer is a commonly used component during the assembly of optical elements; the camera is a CCD camera (CMOS camera can also be used);

[0056] The camera, the first liquid lens, the first lens, the semi-reflective and semi-transmissive lens, the second liquid lens, the second lens, the working distance adjustment column, and the conical reflector are arranged in sequence from top to bottom; the first liquid lens and the first lens form the first lens group, and the second liquid lens and the second lens form the second lens group;

[0057] The length of the working distance adjustment column is adjustable, for example, it can be adjusted through an existing axially telescopic structure so as to be able to perform imaging detection on the inner wall of holes with different diameters;

[0058] The point light source is arranged on the side of the semi-reflective and semi-transmissive lens; the inclination angle of the conical reflector is 45°, and it is in the shape of a flared trumpet with a smaller upper part and a larger lower part; during detection, the conical reflector extends into the hole. The light emitted from the point light source is reflected downward by the semi-reflective and semi-transmissive lens, and after passing through the second lens group, it forms approximately parallel illumination light, and then is reflected by the conical reflector with an inclination angle of 45° to form 360° radial illumination light, realizing 360° illumination of the inner wall of the hole;

[0059] Such as Figure 4 As shown, the image acquisition head is a complete whole, that is, the camera, the first liquid lens, the first lens, the semi-reflective and semi-transmissive lens, the second liquid lens, the second lens, the working distance adjustment column, the conical reflector and the point light source are all assembled on the same housing to form an integrated image acquisition head, which is convenient for on-site detection.

[0060] Figure 1-2 For the cross-sectional view and three-dimensional view of the internal thread in the blind hole, the method for detecting the internal thread in the blind hole by using the above device includes the following steps:

[0061] 1) Insert the head of the image acquisition head into the hole to be measured of the workpiece to be measured. The light emitted from the point light source is reflected downward by the semi-reflective and semi-transmissive lens and forms approximately parallel coaxial illumination light traveling downward after being sorted out by the second lens group;

[0062] 2) The approximately parallel illumination light coming out of the second lens group is reflected by the conical reflector with a 45° inclination angle and further becomes light that irradiates horizontally in all directions, illuminating the internal thread from an almost vertical angle and providing a light field illumination for subsequent imaging;

[0063] 3) The light reflected or scattered from the surface of the illuminated thread is reflected by the conical reflector with a 45° inclination angle into the second lens group, and then passes through the semi-reflective and semi-transmissive lens and the first lens group in sequence. Without rotation, the internal thread is imaged 360° on the image plane where the camera image sensor is located, obtaining a 360-degree image of the internal thread. According to the different inner diameters of the blind hole, adjust the length of the working distance adjustment column to roughly adjust to a corresponding relationship between the object distance and the image distance, and then adjust the first liquid lens and the second liquid lens to obtain clear imaging. By analyzing the obtained internal thread image, the quality of the internal thread is detected. The analysis of the image can be directly observed by the naked eye or analyzed by existing software. For example, 8 thread images can be extracted from each image, and it is controlled to take an image every 8 pitches along the axial direction of the internal thread until the entire axial shooting and analysis of the internal thread are completed.

[0064] Embodiment 2

[0065] On the basis of Embodiment 1, the following further improvements are made: As Figure 4 shown, the non-rotating 360° quality inspection device for the inner wall of the hole further includes a horizontal machine table, a Z-direction column, a Z-axis, and a connecting cross beam; the Z-direction column is vertically arranged on the horizontal machine table, the Z-axis is installed on the Z-direction column along the Z direction, a scale value is provided on the Z-axis, one end of the connecting cross beam is installed on the Z-axis through a slider and can linearly move along the Z-axis, and the slider is driven to move up and down through a lead screw (or linear motor), thereby driving the connecting cross beam and the image acquisition head to move up and down along the Z-axis. An existing electronically controlled automated structure can be used to achieve automatic control. The other end of the connecting cross beam is connected to the image acquisition head, with a camera on the image acquisition head and a conical reflector below; the aforementioned cross beam can move up and down along the Z-axis to achieve scanning detection of the entire axial direction of the threaded hole.

[0066] An XY moving platform is provided on the horizontal machine table, and a fixture for installing the workpiece to be measured is provided on the XY moving platform. The position of the fixture on the XY moving platform is adjustable in the X direction and the Y direction. The XY movement can drive the workpiece to be measured to make a horizontal movement within a certain range to ensure the coaxiality between the hole to be measured on the workpiece to be measured and the image acquisition head, and achieve clear imaging of 360°.

[0067] The method for detecting the internal thread in the blind hole using the above device is the same as that in Embodiment 1, except that: As Figure 4 shown, before detection, the workpiece to be measured is clamped on the fixture of the XY moving platform, the head of the image acquisition head is inserted into the hole to be measured of the workpiece to be measured, the length of the working distance adjustment column shaft is adjusted to obtain a rough corresponding relationship between the object distance and the image distance so as to obtain an image of the internal thread, and then the liquid lens 1 and the liquid lens 2 are adjusted to make the image clear. Then, by adjusting the horizontal position of the fixture on the XY moving platform, the coaxiality between the hole to be measured and the image acquisition head is ensured; through the imaging clarity at different angles of 360° of the internal thread, it is judged whether the hole to be measured and the image acquisition head are coaxial: If it is found that it is clearer at some angles and blurrier at some angles, that is, when the imaging clarity at different angles of the internal thread image obtained in step 3) is inconsistent, it means that the central axis of the hole to be measured does not coincide with the central axis of the image acquisition head. At this time, the XY moving platform needs to be adjusted to adjust the position of the workpiece to be measured until the imaging clarity at each angle of the internal thread remains consistent. At this time, the central axis of the hole to be measured coincides with the central axis of the image acquisition head, meeting the condition for further adjusting the liquid lens to achieve clear imaging of 360°; then the liquid lens 1 and the liquid lens 2 are adjusted again to obtain a clear image with consistent clarity of 360° of the inner wall of the hole.

[0068] Through the up and down movement of the connecting cross beam on the Z-axis, scanning and shooting detection of the entire axial direction of the internal thread is achieved, as Figure 5As shown, 5 thread images can be extracted from each image. Control the camera to take an image every 5 pitches moved along the Z-axis until the entire axial direction of the internal thread is photographed and analyzed.

[0069] As Figure 6 shown, transform the 5 thread images extracted from each image from polar coordinates to Cartesian coordinates, so that the circular thread images are flattened into parallel straight stripes; then splice the stripe images extracted and unfolded from each image in sequence to form a complete two-dimensional thread image (the entire axial direction of the internal thread). By analyzing the complete two-dimensional thread image, the quality inspection of the internal thread is realized.

[0070] Figure 7 The thread image with defects detected in one inspection. 7 thread images can be extracted from each image. From the photographed images, the defects of the threads can be clearly seen. Defects less than 10μm can be clearly imaged with an accuracy of 100%, meeting the installation requirements of aerospace equipment and nuclear equipment.

Claims

1. A non-rotating 360° quality inspection device for the inner wall of a hole, characterized in that: It includes an image acquisition head; the image acquisition head includes a camera, a first liquid lens, a first lens, a semi-reflective semi-transmissive lens, a second liquid lens, a second lens, a conical reflector, and a point light source; The camera, the first liquid lens, the first lens, the semi-reflective semi-transmissive lens, the second liquid lens, the second lens, and the conical reflector are arranged in sequence from top to bottom; the first liquid lens and the first lens form a first lens group, and the second liquid lens and the second lens form a second lens group; The point light source is arranged on the side of the semi-reflective semi-transmissive lens; the inclination angle of the conical reflector is 45°, and it is in the shape of a flared trumpet with a smaller upper part and a larger lower part; the light emitted from the point light source is reflected downward by the semi-reflective semi-transmissive lens, and after passing through the second lens group, it forms approximately parallel illumination light, and then is reflected by the conical reflector with an inclination angle of 45° to form 360° radial illumination light, realizing 360° illumination of the inner wall of the hole; It also includes a working distance adjustment column, the length of the working distance adjustment column is adjustable, and the two ends in the length direction of the working distance adjustment column are respectively connected to the second lens and the conical reflector; through the coarse adjustment of the working distance adjustment column, combined with the fine adjustment of the first liquid lens and the second liquid lens, clear imaging is achieved; The camera, the first liquid lens, the first lens, the semi-reflective semi-transmissive lens, the second liquid lens, the second lens, the working distance adjustment column, the conical reflector, and the point light source are all integrated on the same housing to form an integrated image acquisition head; It also includes a horizontal machine table, a Z-direction column, a Z-axis, and a connecting cross beam; the Z-direction column is vertically arranged on the horizontal machine table, and the Z-axis is installed on the Z-direction column; one end of the connecting cross beam is installed on the Z-axis and can linearly move along the Z-axis, and the other end of the connecting cross beam is connected to the image acquisition head, with the camera on the image acquisition head on the top and the conical reflector on the bottom; An XY moving platform is arranged on the horizontal machine table, a fixture for installing the workpiece to be measured is arranged on the XY moving platform, and the positions of the fixture in the X direction and the Y direction on the XY moving platform are adjustable; a scale value is arranged on the Z-axis; the camera is a CCD camera or a CMOS camera.

2. A method for detecting the quality of the inner wall of a hole, which is detected by using the non-rotating 360° quality detection device for the inner wall of a hole described in claim 1, and is characterized in that: It includes the following steps: 1) Insert the head of the image acquisition head into the hole to be measured of the workpiece to be measured. The light emitted from the point light source is reflected downward by the semi-reflective semi-transmissive lens and forms approximately parallel coaxial illumination light traveling downward after being sorted by the second lens group; 2) The approximately parallel illumination light coming out of the second lens group is reflected by the conical reflector with a 45° inclination angle and further becomes light that irradiates around in an approximately horizontal direction, illuminating the inner wall of the hole from an almost vertical angle and providing light field illumination for imaging; 3) The light reflected and scattered by the illuminated inner wall surface of the hole is reflected by the conical reflector with a 45° inclination angle and enters the second lens group, and then passes through the semi-reflective semi-transmissive lens and the first lens group in sequence. Without rotation, the 360° image of the inner wall of the hole is formed on the image plane where the image sensor of the camera is located, obtaining a 360-degree image of the inner wall of the hole. By analyzing the obtained image of the inner wall of the hole, the detection of the quality of the inner wall of the hole is realized.

3. The method for detecting the quality of the inner wall of the hole according to claim 2, characterized in that: Before detection, the workpiece to be measured is clamped on the fixture of the XY moving platform. The head of the image acquisition head is inserted into the hole to be measured of the workpiece to be measured. The length of the working distance adjustment column shaft is adjusted to obtain a rough correspondence between the object distance and the image distance so as to obtain an image of the inner wall of the hole. Then, liquid lens 1 and liquid lens 2 are adjusted to make the image clear. Next, the horizontal position of the fixture on the XY moving platform is adjusted to ensure the coaxiality between the hole to be measured on the workpiece to be measured and the image acquisition head.

4. The method for detecting the quality of the inner wall of the hole according to claim 3, characterized in that: The method for judging whether the hole to be measured is coaxial with the image acquisition head is as follows: when the imaging clarity at different angles of the inner wall image of the hole obtained in step 3) is inconsistent, it indicates that the central axis of the hole to be measured does not coincide with the central axis of the image acquisition head. At this time, the XY moving platform needs to be adjusted to adjust the position of the workpiece to be measured until the imaging clarity at each angle of the inner wall of the hole is consistent, indicating that the central axis of the hole to be measured coincides with the central axis of the image acquisition head.

5. The method for detecting the quality of the inner wall of the hole according to claim 4, characterized in that: After the hole to be measured is coaxial with the image acquisition head, liquid lens 1 and liquid lens 2 are adjusted again to obtain a clear image with consistent clarity of 360° of the inner wall of the hole. Then, by adjusting the position of the connecting beam on the Z axis, the entire axial scanning and shooting detection of the inner wall of the hole is realized. Assume that the inner wall image of the hole with a height of h is extracted from each image, and an image is taken every time the connecting beam moves h height on the Z axis.

6. The method for detecting the quality of the inner wall of the hole according to claim 5, characterized in that: The inner wall image of the hole with a height of h extracted from each image is transformed from polar coordinates to Cartesian coordinates, so that the circular inner wall image of the hole is flattened into a planar image. Then, the planar images at each height of h are spliced in sequence to form a complete two-dimensional planar image. By analyzing the complete two-dimensional planar image, the quality detection of the inner wall of the hole is realized.

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