Flaw detection device and flaw detection method for inner wall defects of large-diameter long hollow shaft

Abstract

The invention particularly relates to a flaw detection device and method for inner wall defects of a large-diameter long hollow shaft, and the flaw detection device comprises a detection module which is used for collecting defect information of the inner wall of the shaft; the movement mechanism is used for controlling and positioning the movement of the detection module; the centering supporting structure is used for supporting and centering the mechanism; the centering supporting structure is installed at the free end of the movement mechanism so as to improve the supporting rigidity and centering of the cantilever part. The mounting bracket is used for fixing the whole device at a mounting position, and the height of the mounting bracket is adjusted according to the actual horizontal placement height of the large-diameter long hollow shaft so as to realize alignment of the mechanism without performing adjustment, re-clamping and other operations on a measured piece; performing defect display on the to-be-detected part in a fluorescent penetration mode; the detection module and the movement mechanism are synchronized in position, collected images are marked, defect images are processed and judged on the upper computer, and high-quality and automatic collection of images of the inner wall of the horizontally-placed large-size hollow shaft is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of flaw detection, and in particular to a flaw detection device and a flaw detection method for inner wall defects of a large-diameter long hollow shaft. Background Art

[0002] Hollow shafts are important transmission parts in many types of machinery. Hollow shafts are lightweight, easy to install, and have good heat dissipation performance, and are widely used in the automotive, aerospace and other fields. The performance and service life of defective hollow shafts will be affected to a certain extent. As the service life of the parts increases, the defects of the hollow shafts will further expand, causing the mechanical equipment to malfunction and even cause serious accidents.

[0003] The outer wall detection of the hollow shaft is not limited by space, so it can be detected by certain means. Due to the limited space, the inner wall of the hollow shaft is almost impossible to detect manually, and it is even more impossible to use large mechanisms for automatic detection. At present, there are some deep hole detection methods, but they often use cantilever guide rails and chuck clamping structures for small diameter holes. When the parts are large, the overall structure requirements are too high and almost impossible to achieve; the existing detection modules basically use point measurement and line measurement acquisition methods, which are too inefficient and easily interfered; focus on geometric parameter measurement and fitting, and the detection results are not intuitive enough for flaw detection. The patent application number is CN202410311951.4, and the invention name is "A small diameter deep hole morphology measurement device". It uses a point spectrum confocal sensor for measurement. In the flaw detection scenario, ensuring the acquisition efficiency will cause missed detection due to the acquisition interval. If the entire surface is scanned, the efficiency is extremely low, and the guide rail and clamping structure are not suitable for large parts. Finally, the result is obtained by fitting, and the error is large under full-domain detection. The patent application number is CN202211422254.3, and the name of the invention is "A circular deep hole detection device and system". It uses laser diffraction photography to measure the diameter, and there are also problems of low efficiency, frequency aliasing and scene mismatch. For large-area detection scenarios such as inner surface defect detection of large-diameter long hollow shafts, the above method cannot give full play to its advantages. At the same time, the relatively smooth metal processing surface has high reflective properties. If traditional point and line light sources are used, it will cause overexposure, resulting in incomplete collected image information. Therefore, it is necessary to design a device and method to realize the efficient collection of inner wall surface information of large-diameter long hollow shafts, so as to detect defects on the inner wall of parts in a timely manner. Summary of the invention

[0004] The purpose of the present invention is to provide a device for detecting inner wall defects of a large-diameter long hollow shaft in view of the shortcomings of the prior art, comprising:

[0005] A motion mechanism, the motion mechanism comprising a rotation mechanism and a translation mechanism; the translation mechanism can drive the free end to move forward and backward; the rotation mechanism is arranged at the end of the translation mechanism;

[0006] The detection module is installed on the rotating mechanism and is used to collect the image data signal of the inner wall of the hollow shaft.

[0007] A centering support structure, which is arranged on the motion mechanism and is used to adjust the distance between the motion mechanism and the inner wall of the hollow shaft;

[0008] A mounting bracket is connected to one end of the translation mechanism and is used to support the motion mechanism and adjust the flaw detection angle of the translation mechanism.

[0009] Furthermore, the detection module includes an image sensor mounting plate, on which a lens, an image sensor and a light source mounting plate are mounted, and on which a light source is mounted.

[0010] Furthermore, at least two mounting brackets are provided and are tripods.

[0011] Furthermore, the translation mechanism is an electric push rod.

[0012] Furthermore, the centering support structure includes a central sleeve sleeved on the end of the electric push rod and a plurality of support units circumferentially arranged outside the central sleeve.

[0013] Furthermore, the support unit includes two double-threaded guide rods fixedly connected to the center sleeve, the other ends of the two double-threaded guide rods are threadedly connected to the limit nut after passing through the retaining frame, the two double-threaded guide rods are provided with threaded compression force adjustment nuts, a limit gasket is provided under the compression force adjustment nut, a spring is also sleeved on the outer side of the double-threaded guide rod and the two ends of the spring are located between the limit gasket and the retaining frame, and a roller is provided on the retaining frame.

[0014] Furthermore, the rotating mechanism includes a conductive slip ring, a stator of the conductive slip ring is fixedly connected to the end of the electric push rod, a rotor of the conductive slip ring is fixedly connected to the image sensor mounting plate, and the rotor of the conductive slip ring is meshed and driven by the output shaft of the servo motor.

[0015] A method for detecting inner wall defects of a large-diameter long hollow shaft, comprising:

[0016] Carry out conventional fluorescent penetrant testing steps on the parts to be tested to clean, penetrate and develop the inner holes;

[0017] The central angle of the translation mechanism is adjusted by adjusting the mounting bracket so that the central axis of the translation mechanism is installed in place in a direction parallel to the axis of the hole of the part to be tested. The mounting bracket is fixed, and the upper computer controls the rotation mechanism and the translation mechanism to drive the end detection module to move, establish a cylindrical surface coordinate system, and perform cylindrical surface coordinate positioning;

[0018] The single acquisition area is determined according to the detection conditions, and the interval time of rotation and horizontal movement for continuous acquisition is set. The upper computer repeatedly controls the rotation mechanism and the translation mechanism so that the detection module acquires the area passed by the acquisition to cover the entire detection surface;

[0019] The detection module collects the inner wall image of an area each time, and the host computer performs statistical marking according to the defective image and the corresponding position signal transmitted by the motion mechanism to obtain the inner wall defect information of the part to be tested.

[0020] Furthermore, the position signal transmitted by the motion mechanism includes a rotation angle data signal of the rotation mechanism and a horizontal displacement data signal of the horizontal mechanism.

[0021] Furthermore, the image background collected by the detection module is dark, the defects are displayed as relatively bright penetrant colors, and post-processing such as enhancement and binarization is used to increase the distinction between the background and the defects;

[0022] The position corresponding to each defect image is obtained according to the mark of image acquisition, and then the fluorescent display position of the defect in the single defect image is determined. The defect image position and the display position of the defect in the image are comprehensively analyzed to obtain the position of the defect, and the defects are counted to obtain the inner wall defect information of the part to be tested.

[0023] The beneficial effects of the present invention are as follows: the detection device for the inner wall of a long hollow shaft with a large diameter described in the embodiment of the present application includes a detection module, a motion mechanism, a centering support structure and a mounting bracket. The detection module includes an image sensor, a lens, and a light source, which can collect an area at a time; the image sensor can collect and output image signals to obtain inner wall surface information; the lens can gather light and focus on the target surface of the image sensor; the light source can emit light of sufficient power to the inner wall surface to be measured. The motion mechanism includes a rotating mechanism and a translation mechanism; the translation mechanism is a telescopic rod structure that can drive the structure at its end to move horizontally; the rotating mechanism can drive the structure installed thereon to realize circular motion around the axis. The centering support structure is arranged on the motion mechanism to improve the rigidity of the motion mechanism and the centering of the inner hole, and can ensure that it is in close contact with the inner wall of the shaft and bears part of the gravity of the entire device. The mounting bracket is used for fixing, so that the fixed part is stationary relative to the ground during operation. The rotating mechanism described in the embodiment of the present application is capable of point-to-point positioning of cylindrical coordinates. By adjusting the centering support structure, the end mounting structure can be ensured to be at the center of the hole. With the help of control and signal transmission, it is easy to realize automation. The defect display method of fluorescent penetration can effectively reduce the high reflection of the metal surface and increase the contrast between the defect and the background. With the help of the host computer for complex post-processing, marking and calculation, the inner wall defects can be located, which can be used for reference and program judgment by professionals, so as to detect the inner wall defects in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 It is a schematic diagram of the structure of the detection module of the present invention;

[0026] Figure 3 It is a schematic diagram of the support unit structure of the present invention;

[0027] Figure markings: 1-translational mechanism, 2-mounting bracket, 3-rotation mechanism, 4-centering support structure, 5-detection module, 6-conductive slip ring, 7-host computer, 8-image sensor mounting plate, 9-motion mechanism, 10-lens, 11-light source mounting plate, 12-image sensor, 13-light source, 14-limiting nut, 15-center sleeve, 16-limiting gasket, 17-roller, 18-retaining frame, 19-spring, 20-compression force adjusting nut, 21-double-headed threaded guide rod, 22-support unit. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Please refer to Figures 1 to 3 , a large diameter long hollow shaft inner wall defect detection device provided in this embodiment includes:

[0030] The detection module 5 includes an image sensor 12, a lens 10, and a light source 13; the image sensor 12 can collect and output image signals; the lens 10 can gather light and focus it on the target surface of the image sensor 12; the light source 13 is ultraviolet light, which can provide sufficient illumination during detection.

[0031] The motion mechanism 9 includes a rotating mechanism 3 and a translation mechanism 1; the translation mechanism 1 is a telescopic rod structure, and the rotating mechanism is not limited to a worm gear transmission rotating table structure and an existing rotating platform, and is a conductive slip ring 6 in the implementation of this application.

[0032] The centering support structure 4 is arranged on the moving mechanism 9, and is used to improve the rigidity and inner hole centering of the moving mechanism 9. It can ensure that it is in close contact with the inner wall of the shaft and bears part of the gravity of the entire device. It is used as auxiliary centering during the initial installation process. The support unit of the centering support structure can manually adjust the tightness of each spring 19 through the compression force adjustment nut 20 to adjust the initial load of the spring 19.

[0033] The mounting bracket 2 is used to fix the position of the entire device to ensure the stable operation of the device. When in use, the mounting bracket 2 is placed and installed along the axis of the part to be tested after the standard fluorescent penetration imaging treatment. The specific placement method of the part to be tested can be a part bracket, cement table and other structures, and no specific requirements are made here. Due to the large diameter and long hollow shaft, its mass is large, and no fixture or other structure is required for stable placement. It is only necessary to ensure that the part to be tested is placed horizontally and does not move. Adjust the preload of the vertical downward support unit of the centering support structure 4 to resist gravity. Adjust the height of the mounting bracket 2 so that the centering support structure 4 is horizontal with the axis of the part to be tested. It can be adjusted directly by manual visual means, and the adjustment method is not specified here. Optionally, the mounting bracket 2 can be a fixed bracket according to a specific detection scenario.

[0034] All devices of the detection module 5 are turned on, and the focal length, aperture and exposure parameters of the image sensor 12 and the lens 10 are manually adjusted according to the acquisition distance, and the brightness and illumination angle of the light source 13 are adjusted.

[0035] The host computer 7 controls the motion mechanism 9 to drive the detection module 5 at the free end to move in the hollow shaft, the translation mechanism 1 realizes horizontal drive, and the rotation mechanism 3 realizes circular rotation around the axis, so that the detection module 5 can collect wall information for detection.

[0036] The inner wall surface is divided into blocks according to the field of view of a single acquisition, and the software controls the movement of the motion mechanism 9 according to the block parameters. The detection module 5 automatically acquires all the blocks to complete the acquisition of the defect image of the entire inner wall surface.

[0037] During the entire movement process, the centering support structure 4 ensures that the rotation center of the detection module is concentric with the inner wall surface of the hollow shaft, and when the extension amount of the translation mechanism 1 is long, the centering support structure 4 can reduce the deflection of the free end, thereby enabling the hollow shaft inner wall detection device described in the embodiment of the present application to stably collect the inner wall surface information of the hollow shaft.

[0038] As can be seen from the above scheme, the present application is driven by a motion mechanism, which includes a translation mechanism 1 and a rotation mechanism 3 installed at its end. The translation mechanism 1 adopts an electric push rod structure, which can drive the detection module 5 to move horizontally within a certain stroke. The translation mechanism 1 and the rotation mechanism 3 can be connected to sensors and control chips to enable point-to-point positioning of the detection module 5 within the range of motion of the cylindrical surface, which is easy to realize automation. In actual production, manual and other forms of control can be adopted.

[0039] like Figure 1 In this embodiment, the translation mechanism 1 is supported by the mounting bracket 2 to fix the translation mechanism 1. The mounting bracket 2 may be connected by threaded connection, welding connection, adhesive connection, etc., which is not specified in this application. Figure 1 As shown, there are two mounting brackets 2, which are arranged in a horizontal direction with an interval in front and back.

[0040] In this embodiment, the centering support structure 4 is fixedly arranged at the end of the translation mechanism 1. The centering support structure 4 is used for centering and overall support of the detection module 5. The centering support structure 4 includes three evenly distributed support units 22. Figure 3 As shown, the support unit 22 is connected to the central sleeve 15, and the support unit 22 includes a roller 17, a retaining frame 18, a double-threaded guide rod 21, a support spring 19, a compression force adjustment nut 20, a limit nut 14, and a limit washer 16. The support unit 22 can not only be compressed to adapt to the space when the diameter of the inner cylindrical hole changes, but also adjust the initial load before use to offset the asymmetric compression caused by the overall gravity to achieve centering.

[0041] In this embodiment, for example Figure 1The rotating mechanism 3 may be, but is not limited to, an existing electric hollow rotating table, or may be, but is not limited to, a conductive slip ring 6. Specifically, the stator of the conductive slip ring 6 is fixedly connected to the end of the electric push rod 2, the rotor of the conductive slip ring 6 is fixedly connected to the image sensor mounting plate 8, and the rotor of the conductive slip ring 6 is provided with meshing teeth and meshed and driven with the output shaft of the servo motor. The upper computer 7 may directly control the servo motor to control the rotation of the rotor, and collect angle data signals through an encoder arranged on the servo motor.

[0042] In this embodiment, the detection module 5 is fixedly disposed at the rotatable end of the rotating mechanism 3. Figure 2 As shown, in this embodiment, the detection module 5 includes an image sensor 12, a lens 10 and a light source 13. The image sensor 12 and the lens 10 are directly connected and fixed on the image sensor mounting plate 8; the light source 13 is a black light flashlight, which is connected to the light source mounting plate 11; the image sensor mounting plate 8 and the light source mounting plate 11 are fixed by threaded connection, which is equivalent to a hinge connection when the thread is loosened, and the angle can be adjusted.

[0043] In this embodiment, the signal transmission and power supply are carried out by wired transmission, such as Figure 1 As shown, a conductive slip ring 6 is provided between the detection module 5 and the rotation mechanism 3. When working, the conductive slip ring 6 enables the cables of the detection module 5 and the translation mechanism 1 to rotate relatively without winding.

[0044] The present application also provides a method for detecting the inner wall defect detection device of the large-diameter long hollow shaft, comprising:

[0045] First, the inner wall surface of the part to be inspected is treated with fluorescent penetration, and the steps of pre-treatment cleaning, penetration, removal, drying and imaging are taken according to relevant standards to ensure the effectiveness of the fluorescent penetration results.

[0046] After the fluorescent penetration, the part to be tested is placed on a cement V-shaped table to ensure that it is placed horizontally and does not move.

[0047] Adjust the anti-gravity preload of the vertically downward supporting unit of the centering support structure 4, place the mounting bracket 2 along the axis of the part to be measured, visually adjust the height of the mounting bracket 2 so that the centering support structure 4 is level and fixed with the axis of the part to be measured. During the process, place a level on the translation mechanism 1 to ensure its levelness, and use the roller of the centering support structure 4 to assist in initial centering.

[0048] After all the device lines are installed, the upper computer 7 software control is started to realize the automation of the detection process. After starting, the motion mechanism will complete the image acquisition of the circular surface at the current horizontal position in a mode of collecting an area and rotating an angle. After the current position acquisition is completed, it moves to the next position and collects the circular surface image again until it moves to the end of the stroke or the entire surface acquisition is completed.

[0049] The collected data will be synchronously transmitted to the host computer 7 as a backup. Relying on the computing power of the host computer 7, the collected image is contrast enhanced, grayed, and edge detected by software in the background to obtain another surface defect data set relative to the original collected image data set. Both sets of data are retained at the same time for subsequent use. In this embodiment, the host computer 7 is a personal computer.

[0050] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0051] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A device for detecting inner wall defects of a large diameter long hollow shaft, comprising: A motion mechanism, the motion mechanism comprising a rotation mechanism and a translation mechanism; the translation mechanism can drive the free end to move forward and backward; the rotation mechanism is arranged at the end of the translation mechanism; The detection module is installed on the rotating mechanism and is used to collect the image data signal of the inner wall of the hollow shaft. A centering support structure, which is arranged on the motion mechanism and is used to adjust the distance between the motion mechanism and the inner wall of the hollow shaft; A mounting bracket is connected to one end of the translation mechanism and is used to support the motion mechanism and adjust the flaw detection angle of the translation mechanism.

2. A device for detecting inner wall defects of a large diameter long hollow shaft as claimed in claim 1, characterized in that: The detection module comprises an image sensor mounting plate, on which a lens, an image sensor and a light source mounting plate are mounted, and on which a light source is mounted.

3. A device for detecting inner wall defects of a large diameter long hollow shaft as claimed in claim 1, characterized in that: At least two mounting brackets are provided and are tripods.

4. A device for detecting inner wall defects of a large diameter long hollow shaft as claimed in claim 2, characterized in that: The translation mechanism is an electric push rod.

5. A device for detecting inner wall defects of a large diameter long hollow shaft as claimed in claim 4, characterized in that: The centering support structure includes a central sleeve sleeved on the end of the electric push rod and a plurality of support units circumferentially arranged outside the central sleeve.

6. A device for detecting inner wall defects of a large diameter long hollow shaft as claimed in claim 5, characterized in that: The support unit includes two double-threaded guide rods fixedly connected to the center sleeve, the other ends of the two double-threaded guide rods are threadedly connected to the limit nuts after passing through the retaining frame, the two double-threaded guide rods are provided with threaded compression force adjustment nuts, a limit gasket is provided under the compression force adjustment nut, a spring is also sleeved on the outer side of the double-threaded guide rod and the two ends of the spring are located between the limit gasket and the retaining frame, and a roller is provided on the retaining frame.

7. A device for detecting inner wall defects of a large diameter long hollow shaft as claimed in claim 4, characterized in that: The rotating mechanism comprises a conductive slip ring, a stator of the conductive slip ring is fixedly connected to the end of the electric push rod, a rotor of the conductive slip ring is fixedly connected to the image sensor mounting plate, and the rotor of the conductive slip ring is meshed and driven by the output shaft of the servo motor.

8. A method for detecting inner wall defects of a large diameter long hollow shaft applied to the flaw detection device according to any one of claims 1 to 7, characterized in that: include: Carry out conventional fluorescent penetrant testing steps on the parts to be tested to clean, penetrate and develop the inner holes; The central angle of the translation mechanism is adjusted by adjusting the mounting bracket so that the central axis of the translation mechanism is installed in place in a direction parallel to the axis of the hole of the part to be tested. The mounting bracket is fixed, and the upper computer controls the rotation mechanism and the translation mechanism to drive the end detection module to move, establish a cylindrical coordinate system, and perform cylindrical coordinate positioning; The single acquisition area is determined according to the detection conditions, and the interval time of rotation and horizontal movement for continuous acquisition is set. The upper computer repeatedly controls the rotation mechanism and the translation mechanism so that the detection module acquires the area passed by the acquisition to cover the entire detection surface; The detection module collects the inner wall image of an area each time, and the host computer performs statistical marking according to the defective image and the corresponding position signal transmitted by the motion mechanism to obtain the inner wall defect information of the part to be tested.

9. A method for detecting inner wall defects of a large diameter long hollow shaft as claimed in claim 8, characterized in that: The position signal transmitted by the motion mechanism includes a rotation angle data signal of the rotation mechanism and a horizontal displacement data signal of the horizontal mechanism.

10. A method for detecting inner wall defects of a large diameter long hollow shaft according to claim 9, characterized in that: The image collected by the detection module has a dark background, and defects are displayed as relatively bright penetrant colors, and post-processing such as enhancement and binarization is used to increase the distinction between the background and defects; The position corresponding to each defect image is obtained according to the mark of image acquisition, and then the fluorescent display position of the defect in the single defect image is determined. The defect image position and the display position of the defect in the image are comprehensively analyzed to obtain the position of the defect, and the defects are counted to obtain the inner wall defect information of the part to be tested.

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