Appearance defect detection device and method for PCD turning tool

Abstract

The invention relates to the technical field of appearance detection, in particular to a PCD turning tool appearance defect detection device and a PCD turning tool appearance defect detection method. The PCD turning tool appearance defect detection device comprises a detection table, a high-definition image magnifying shooting device and light supplementing equipment, and the high-definition image magnifying shooting device, a controller, the light supplementing equipment and a driving assembly are installed at the upper end of the detection table; a quick connecting unit used for fixing a PCD turning tool is installed on the inner side of the top end of the driving assembly. The quick connection unit comprises a hollow connection block with a T-shaped vertical projection, and a plurality of anti-skid grooves are annularly formed in one end of the connection block at equal intervals. According to the invention, through the arrangement of the quick connection unit, a detection piece can be quickly fixed and positioned to a central position, so that the detection efficiency and accuracy can be effectively improved; meanwhile, the problems of vibration and image shaking caused by installation eccentricity are effectively solved, compensation is conducted through a pure software algorithm, on the premise that existing hardware is not changed, the stability and the measurement precision of detected images are remarkably improved, and meanwhile the detection efficiency and the equipment universality are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of appearance inspection technology, specifically to a device and method for detecting appearance defects in PCD turning tools. Background Technology

[0002] PCD (polycrystalline diamond) turning tools, as a type of superhard tool, are widely used in high-speed precision turning of difficult-to-machine materials such as non-ferrous metals and composite materials due to their extremely high hardness, wear resistance, and excellent service life. Their appearance quality, such as whether there are defects such as chipping, micro-cracks, uneven coating, and scratches on the cutting edge, directly determines the initial performance and service life of the tool. Therefore, strict appearance defect inspection of PCD turning tools during the manufacturing process is a key link to ensure product quality.

[0003] Currently, the industry generally uses automated inspection equipment based on machine vision to complete this task. A typical inspection process is as follows: the tool holder of the PCD turning tool is magnetically attached to a rotating platform, and then the platform is driven to rotate the turning tool. At the same time, a high-resolution industrial camera above continuously acquires images, and the image processing algorithm is used to analyze and identify defects in key parts such as the cutting edge, rake face, and flank face.

[0004] However, this traditional detection method, due to the fact that the magnetic fixation only provides axial attraction force and lacks effective radial positioning constraint on the cylindrical surface of the tool holder, results in a random and non-negligible eccentricity between the actual central axis of the PCD cutting tool and the theoretical rotational central axis of the rotary platform during each clamping. This eccentricity problem will lead to a series of consequences:

[0005] Dynamic vibration problem: During high-speed rotation, the eccentric mass will generate periodic centrifugal force, causing slight vibration of the entire detection system. This vibration will not only reduce the clarity of image acquisition and cause image blurring, but may also affect the accuracy and lifespan of the equipment's mechanical structure in the long run.

[0006] Image stability problem: In the camera's field of view, eccentricity causes the image of the cutting tool to move along an eccentric trajectory instead of rotating around a fixed point. This periodic shaking ("running") of the image makes it difficult for subsequent image processing algorithms to continuously and superimposedly observe and analyze the same position of the tool under a unified coordinate reference.

[0007] Measurement error problem: Image shaking directly introduces additional measurement error. For defect detection that requires subpixel accuracy (such as the measurement of micron-level chipping), the systematic error caused by eccentricity may even be greater than the size of the defect itself, leading to misjudgment and missed detection, which seriously reduces the reliability and accuracy of the detection results. Therefore, in order to address the above problems, a PCD turning tool appearance defect detection device and method are proposed. Summary of the Invention

[0008] The purpose of this invention is to provide a device and method for detecting surface defects in PCD turning tools, so as to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A device and method for detecting surface defects in PCD turning tools includes a detection table, a high-definition magnifying image capture device, and a supplementary lighting device. The detection table has a high-definition magnifying image capture device, a controller, a supplementary lighting device, and a drive assembly mounted on its upper end. A quick-connect unit for fixing the PCD turning tool is mounted on the inner side of the top of the drive assembly. The quick-connect unit includes a hollow connecting block with a T-shaped vertical projection. One end of the connecting block has multiple anti-slip grooves spaced equidistantly in an annular pattern, and the other end has an external thread. An annular hollow groove is formed inside the threaded side of the connecting block, and multiple through holes are spaced equidistantly in an annular pattern inside the connecting block. A positioning assembly is installed inside each through hole. A semi-external piston assembly is installed inside one end of the annular hollow groove. The positioning assembly includes a positioning shell, and a positioning post is slidably connected to the positioning shell through a sealing plate. A return spring is fixedly connected to one end of the positioning post in the annular hollow groove.

[0011] As a further optimization of the present invention, the external piston assembly includes a piston plate, one end of which is fixedly connected to an annular plate via multiple connecting posts. The piston plate is annularly arranged and disposed inside an annular hollow groove. The connecting posts and connecting blocks are slidably connected, and the cross-section of one side of the annular plate is semi-circular.

[0012] As a further optimization of the present invention, the other end of the reset spring is fixedly connected to the inner wall of the annular hollow groove, the positioning shell and the through hole correspond one-to-one, the positioning shell is fixedly connected to the inside of the connecting block through the through hole, and the top of the positioning post exposed in the hollow position inside the connecting block is arc-shaped.

[0013] As a further optimization of the present invention, the driving component includes a stand, one end of which is fixedly connected to the housing of the stepper motor, and a positioning post is fixedly connected to the top of the stepper motor spindle. The positioning post has a threaded hole inside, and the threaded hole is a blind hole.

[0014] As a further optimization of the present invention, the positioning post is connected to the connecting block by an external thread through an internally threaded hole, and the positioning post and the connecting block are coaxially arranged.

[0015] As a further optimization of the present invention, it includes the following steps:

[0016] Calibration steps: Install the standard round bar inside the positioning column through the connecting unit, drive the stepper motor to rotate at a constant angular velocity ω for at least 360°, and use a high-definition magnified image capture device to sample the frequency. Continuously acquire M frames of calibration images { },in Let represent the rotation angle corresponding to the i-th frame, i = 1, 2, ..., M, and M ≥ 3;

[0017] Based on the calibration image, the pixel coordinates of the center of the standard rod in the image coordinate system are calculated in each frame using an image processing algorithm. ,in and These represent the horizontal and vertical coordinates of the circle's center in the image coordinate system, respectively.

[0018] Based on the obtained set of center coordinates { The coordinates of the center of the fitted circle are calculated using the least squares circle fitting algorithm. Given the radius R, calculate the initial phase angle φ;

[0019] Online compensation steps: The PCD cutting tool to be tested, in the round bar shape, is mounted at the same position inside the positioning column via a connecting unit. During rotation, the sampling frequency is used... Real-time acquisition and detection of image sequences { },in This represents the k-th sampling time.

[0020] For each frame of detected image The corresponding rotation angle is obtained through a rotary encoder. And calculate the theoretical image offset of the current frame for the detected image. Apply an affine transformation to generate the compensated image. ;

[0021] Output the compensated image Used for display or subsequent defect analysis and processing.

[0022] As a further optimization of the present invention, the image processing algorithm adopts the Hough circle detection algorithm or the edge detection combined with the least squares circle fitting algorithm.

[0023] As a further optimization of the present invention, the sampling frequency is as follows: Satisfies the Nyquist sampling theorem. ≥ 2ω / 360°.

[0024] As a further optimization of the present invention, it also includes an adaptive adjustment step: real-time monitoring of the change in the equivalent eccentricity R, when |ΔR|> When this happens, the calibration procedure is repeated, in which... This is the preset threshold for the change in eccentricity.

[0025] As a further optimization of the present invention, a computer-readable storage medium storing a computer program thereon is characterized in that, when the program is executed by a processor, it implements the steps of the method as described in any one of claims 6-9.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] In this invention, the quick-connect unit can quickly fix the test piece and position it in the center, which can effectively improve the efficiency and accuracy of the test. At the same time, it can effectively overcome the vibration and image shaking problems caused by installation eccentricity. Through pure software algorithm compensation, the stability of the test image and the measurement accuracy are significantly improved without changing the existing hardware, while ensuring the test efficiency and equipment versatility. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 This is a schematic diagram of the quick-connect unit structure of the present invention;

[0030] Figure 3 For the present invention Figure 2 Schematic diagram of the structure at point A in the middle;

[0031] Figure 4 This is a schematic diagram of the location structure of the annular hollow groove in this invention;

[0032] Figure 5 This is a schematic diagram of the semi-external piston assembly structure of the present invention;

[0033] Figure 6 This is a schematic diagram of the positioning component structure of the present invention.

[0034] In the diagram: 1. Testing platform; 2. High-definition magnifying image capture device; 3. Controller; 4. Illumination equipment;

[0035] 5. Quick-connect unit; 51. Connecting block; 52. Anti-slip groove; 53. Annular hollow groove; 54. External thread;

[0036] 55. Semi-external piston assembly; 551. Piston plate; 552. Connecting column; 553. Ring plate;

[0037] 56. Positioning assembly; 561. Positioning housing; 562. Positioning post; 563. Sealing plate; 564. Return spring;

[0038] 57. Perforation;

[0039] 6. Drive assembly; 61. Stand; 62. Stepper motor; 63. Positioning post; 64. Threaded hole. Detailed Implementation

[0040] Please see Figures 1-6 The present invention provides a technical solution:

[0041] A device and method for detecting surface defects in PCD turning tools, comprising a detection table 1, a high-definition magnifying image capture device 2, and a supplementary lighting device 4, characterized in that: the high-definition magnifying image capture device 2, a controller 3, the supplementary lighting device 4, and a drive assembly 6 are installed on the upper end of the detection table 1; a quick-connect unit 5 for fixing the PCD turning tool is installed on the inner side of the top of the drive assembly 6; the quick-connect unit 5 includes a hollow connecting block 51 with a T-shaped vertical projection, one end of the connecting block 51 having a plurality of anti-slip grooves 52 arranged in an annular shape at equal intervals, and the other end of the connecting block 51 having a hollow connecting block 51 with a hollow connecting block 51 arranged in an annular shape at equal intervals. The connecting block 51 has an external thread 54 and an annular hollow groove 53 inside the side with the external thread 54. The connecting block 51 has a plurality of annular equidistant through holes 57 inside, and a positioning component 56 is installed inside each through hole 57. A semi-external piston component 55 is installed on the inner side of one end of the annular hollow groove 53. The positioning component 56 includes a positioning shell 561. A positioning post 562 is slidably connected inside the positioning shell 561 through a sealing plate 563. A return spring 564 is fixedly connected to one end of the positioning post 562 in the annular hollow groove 53.

[0042] As a further implementation of this solution, the external piston assembly 55 includes a piston plate 551. One end of the piston plate 551 is fixedly connected to an annular plate 553 via multiple connecting posts 552. The piston plate 551 is annular and is located inside the annular hollow groove 53. The connecting posts 552 and the connecting block 51 are slidably connected. The cross-section of one side of the annular plate 553 is semi-circular. With the above arrangement, the hydraulic oil inside the annular hollow groove 53 can be squeezed as a whole to apply pressure to the multiple positioning posts 63 to fix the clamping parts and make the fixed position located on the center line.

[0043] As a further implementation of this solution, the other end of the return spring 564 is fixedly connected to the inner wall of the annular hollow groove 53. The positioning shell 561 and the through hole 57 correspond one-to-one. The positioning shell 561 is fixedly connected to the inside of the connecting block 51 through the through hole 57. The top of the positioning post 562 exposed in the hollow position inside the connecting block 51 is arc-shaped. With the above settings, the return spring 564 can be stably limited, and the positioning shell 561 can be stably installed and fixed.

[0044] As a further implementation of this solution, the drive assembly 6 includes a stand 61. One end of the stand 61 is fixedly connected to the housing of the stepper motor 62. A positioning post 63 is fixedly connected to the top of the main shaft of the stepper motor 62. A threaded hole 64 is opened inside the positioning post 63. The threaded hole 64 is a blind hole. With the above settings, the test piece can be driven to rotate stably 360°, thereby ensuring the comprehensiveness of the test.

[0045] As a further implementation of this solution, the positioning post 63 is screwed to the connecting block 51 through the internal threaded hole 64 and the external thread 54. The positioning post 63 and the connecting block 51 are coaxially arranged. Through the above arrangement, the stability of the connection between the positioning post 63 and the connecting block 51 can be further improved.

[0046] As a further implementation of this solution, the technical solution includes the following steps:

[0047] Calibration steps: Install the standard round bar inside the positioning post 63 through the connecting unit 5, drive the stepper motor 62 to rotate at a constant angular velocity ω for at least 360°, and use the high-definition magnified image capture device 2 at a sampling frequency. Continuously acquire M frames of calibration images { },in Let represent the rotation angle corresponding to the i-th frame, i = 1, 2, ..., M, and M ≥ 3;

[0048] Based on the calibration images, the pixel coordinates of the center of the standard rod in the image coordinate system are calculated in each frame using image processing algorithms. ,in and These represent the horizontal and vertical coordinates of the circle's center in the image coordinate system, respectively.

[0049] Based on the obtained set of center coordinates { The coordinates of the center of the fitted circle are calculated using the least squares circle fitting algorithm. and radius R, where:

[0050]

[0051]

[0052] ;

[0053] Calculate the initial phase angle φ:

[0054] ;

[0055] Online compensation steps: The PCD cutting tool to be tested, in the round bar shape, is installed at the same position inside the positioning post 63 via the connecting unit 5. During rotation, the sampling frequency is used. Real-time acquisition and detection of image sequences { },in This represents the k-th sampling time.

[0056] For each frame of detected image The corresponding rotation angle is obtained through a rotary encoder. And calculate the theoretical image offset of the current frame according to the following formula:

[0057]

[0058]

[0059] For the detected image Apply an affine transformation to generate the compensated image. The transformation relationship is defined by the following formula:

[0060]

[0061] Where x and y represent the image pixel coordinates;

[0062] Output compensated image Used for display or subsequent defect analysis and processing, it can compensate for image shaking caused by installation eccentricity with high precision without modifying existing hardware, significantly improving the stability and observation accuracy of the detected image, while greatly reducing the system upgrade cost;

[0063] As a further implementation of this scheme, the image processing algorithm adopts the Hough circle detection algorithm or the edge detection combined with the least squares circle fitting algorithm. By limiting the use of mature and robust image processing algorithms, the high accuracy and reliability of the circle center positioning are ensured, laying a solid foundation for subsequent accurate compensation calculations, while ensuring the feasibility and repeatability of the method.

[0064] As a further technical solution for implementing this plan, the sampling frequency... Satisfies the Nyquist sampling theorem. ≥ 2ω / 360°, limiting the sampling frequency to ensure that all dynamic details during the rotation process can be captured completely, avoiding information loss and aliasing caused by undersampling, and ensuring the integrity and accuracy of calibration and compensation data;

[0065] As a further implementation of this scheme, the technical solution also includes an adaptive adjustment step: real-time monitoring of the change in the equivalent eccentricity R, when |ΔR|> When this happens, the calibration procedure is repeated, in which... An adaptive adjustment mechanism was introduced for the preset threshold of eccentricity change, which enables the system to automatically sense changes in eccentricity caused by thermal deformation of the equipment or loosening of the fixture, and automatically recalibrate, thereby maintaining the detection accuracy and reliability of the system in the long term and reducing the need for manual intervention and maintenance.

[0066] As a further implementation of this solution, a computer-readable storage medium storing a computer program is provided. The program, when executed by a processor, implements the steps of any one of the methods described in claims 6-9, thereby materializing the above methods into a storage medium. This allows the technical solution to be conveniently deployed to existing testing equipment through software distribution, installation, and upgrades, greatly promoting the dissemination and application of the technology.

[0067] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A device for detecting surface defects in a PCD turning tool, comprising a testing table (1), a high-definition magnifying image capture device (2), and a supplementary lighting device (4), characterized in that: The upper end of the testing station (1) is equipped with a high-definition magnified image capture device (2), a controller (3), a supplementary lighting device (4) and a drive assembly (6). The inner side of the top of the drive assembly (6) is equipped with a quick-connect unit (5) for fixing the PCD cutting tool. The quick-connect unit (5) includes a hollow connecting block (51) with a T-shaped vertical projection. One end of the connecting block (51) has multiple anti-slip grooves (52) at equal intervals in an annular shape. The other end of the connecting block (51) has an external thread (54) on its outer side. The side of the connecting block (51) with the external thread (54) has an annular hollow groove (53) inside. The connecting block (51) has multiple through holes (57) at equal intervals in an annular shape inside. Each through hole (57) is equipped with a positioning component (56). A semi-external piston assembly (55) is installed on the inner side of one end of the annular hollow groove (53). The positioning component (56) includes a positioning shell (561), and a positioning post (562) is slidably connected inside the positioning shell (561) through a sealing plate (563). The positioning post (562) is fixedly connected to one end of an annular hollow groove (53) with a return spring (564).

2. The PCD turning tool appearance defect detection device according to claim 1, characterized in that: The external piston assembly (55) includes a piston plate (551), one end of which is fixedly connected to an annular plate (553) via multiple connecting posts (552). The piston plate (551) is annularly arranged and disposed inside an annular hollow groove (53). The connecting posts (552) are slidably connected to the connecting block (51). The cross-section of one side of the annular plate (553) is semi-circular.

3. The PCD turning tool appearance defect detection device according to claim 1, characterized in that: The other end of the reset spring (564) is fixedly connected to the inner wall of the annular hollow groove (53). The positioning shell (561) and the perforation (57) correspond one-to-one. The positioning shell (561) is fixedly connected to the inside of the connecting block (51) through the perforation (57). The top of the positioning post (562) exposed in the hollow position inside the connecting block (51) is arc-shaped.

4. The PCD turning tool appearance defect detection device according to claim 1, characterized in that: The drive assembly (6) includes a stand (61), one end of which is fixedly connected to the housing of a stepper motor (62). A positioning post (63) is fixedly connected to the top of the main shaft of the stepper motor (62). A threaded hole (64) is provided inside the positioning post (63), and the threaded hole (64) is a blind hole.

5. The PCD turning tool appearance defect detection device according to claim 4, characterized in that: The positioning post (63) is spirally connected to the connecting block (51) through the internal threaded hole (64) and the external thread (54). The positioning post (63) and the connecting block (51) are coaxially arranged.

6. A method for detecting surface defects in a PCD turning tool according to any one of claims 1-5, characterized in that: Includes the following steps: Calibration steps: Install the standard round bar inside the positioning column (63) through the connecting unit (5), drive the stepper motor (62) to rotate at a constant angular velocity ω for at least 360°, and use the high-definition magnified image capture device (2) at a sampling frequency Continuously acquire M frames of calibration images { },in Let represent the rotation angle corresponding to the i-th frame, i = 1, 2, ..., M, and M ≥ 3; Based on the calibration image, the pixel coordinates of the center of the standard rod in the image coordinate system are calculated in each frame using an image processing algorithm. ,in and These represent the horizontal and vertical coordinates of the circle's center in the image coordinate system, respectively. Based on the obtained set of center coordinates { The coordinates of the center of the fitted circle are calculated using the least squares circle fitting algorithm. Given the radius R, calculate the initial phase angle φ; Online compensation steps: The PCD cutting tool to be tested is installed at the same position inside the positioning column (63) through the connecting unit (5), and during the rotation, the sampling frequency is used. Real-time acquisition and detection of image sequences { },in This represents the k-th sampling time. For each frame of detected image The corresponding rotation angle is obtained through a rotary encoder. And calculate the theoretical image offset of the current frame for the detected image. Apply an affine transformation to generate the compensated image. ; Output the compensated image Used for display or subsequent defect analysis and processing.

7. The method for detecting appearance defects in a PCD turning tool according to claim 1, characterized in that: The image processing algorithm employs either the Hough circle detection algorithm or an edge detection algorithm combined with a least-squares circle fitting algorithm.

8. The method for detecting appearance defects in a PCD turning tool according to claim 1, characterized in that: The sampling frequency Satisfies the Nyquist sampling theorem. ≥ 2ω / 360°.

9. The method for detecting appearance defects in a PCD turning tool according to claim 1, characterized in that: It also includes an adaptive adjustment step: real-time monitoring of the change in the equivalent eccentricity R, when |ΔR|> When this happens, the calibration procedure is repeated, in which... This is the preset threshold for the change in eccentricity.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 6-9.

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