A sensor for detecting surface defects of a die casting
By using a combination of multicolor light source and color camera in the surface defect detection sensor of die castings, the problems of accuracy and high cycle time in die casting defect detection have been solved, achieving efficient and clear defect imaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- EASY THINKING HANGZHOU TECH CO LTD
- Filing Date
- 2025-05-16
- Publication Date
- 2026-07-24
AI Technical Summary
Existing defect detection methods for die castings rely on manual visual inspection, which has poor accuracy and consistency and cannot meet the high-speed requirements during operation. Furthermore, traditional visual inspection methods are easily affected by differences in surface texture and reflectivity, resulting in a high false detection rate.
The test object is illuminated by at least three different monochromatic light sources (red, green, and blue light), and images are acquired by a color camera. A secondary camera is used to image from multiple angles, enabling the simultaneous acquisition of multiple defect features, reducing image interference and improving image clarity.
It achieves efficient and accurate defect detection during movement, reduces the false detection rate, improves the richness and speed of imaging information, and meets the requirements of high-frequency detection.
Smart Images
Figure CN224553153U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of visual inspection technology, specifically to a sensor for detecting surface defects in die-cast parts. Background Technology
[0002] With the rapid development of the automotive industry, the demand for lightweight vehicles is constantly increasing. Die casting technology has obvious advantages in processing lightweight materials such as aluminum alloys and is therefore widely used. However, die castings may have defects such as cracks, cold shuts, missing material, and drag marks after die casting. Therefore, in order to ensure the quality of die castings, it is necessary to detect various potential defects in the die castings to provide assurance for subsequent production.
[0003] Currently, defect detection in die-cast parts relies entirely on manual visual inspection. Limited by the experience and subjective judgment of the inspectors, this makes it difficult to guarantee accuracy and consistency, and data traceability is impossible. Furthermore, to save time, surface defect detection of die-cast parts must be performed during movement, and traditional visual inspection methods cannot simultaneously meet the requirements of low-exposure photography and high-speed imaging during movement. In addition, the following problems exist during testing: ① Complex surface textures and background interference; ② Uneven brightness in the captured images due to localized differences in reflectivity. Conventional visual inspection imaging methods have poor performance and are prone to false positives, therefore they are not suitable for surface defect detection in die-cast parts. Summary of the Invention
[0004] To address the aforementioned technical problems, this utility model provides a surface defect detection sensor for die-cast parts, which can resolve the conflict between blurred motion images and the demands of high-speed production, and offers advantages such as reduced interference in captured images and clearer defect presentation.
[0005] Therefore, the present invention adopts the following technical solution:
[0006] A surface defect detection sensor for die-cast parts is used to detect surface defects in die-cast parts, including a main camera and a light source group; the light source group includes at least three monochromatic light sources; the same test position of the test part is located within the illumination area of at least three different monochromatic light sources, and the three different monochromatic light sources project red light, green light and blue light respectively;
[0007] The main camera is a color camera, capable of acquiring individual images of the object under test against each monochromatic light source background and / or capable of acquiring mixed images of the object under test against at least three monochromatic light source backgrounds.
[0008] Furthermore, the monochromatic light source in the light source group is a surface light source or a strip light source with a power of not less than 200 watts.
[0009] Furthermore, it also includes a housing, with the main camera and light source assembly embedded on one side of the housing;
[0010] Alternatively, the main camera is embedded in the housing; the light source groups are fixedly connected to the outside of the housing via rigid connecting tubes.
[0011] Furthermore, when the main camera and the light source group are embedded on one side of the housing, each monochromatic light source in the light source group is evenly distributed around the main camera as the center.
[0012] When the main camera is embedded in the housing and the light source group is fixedly connected to the outside of the housing through rigid connecting tubes, each monochromatic light source in the light source group is evenly distributed around the optical axis of the main camera.
[0013] Furthermore, when the main camera is embedded in the housing and the light source group is fixedly connected to the outside of the housing through rigid connecting tubes, each monochromatic light source in the light source group is evenly distributed around the optical axis of the main camera. The optical axis of the main camera has the same angle with the plane where each light source is located, and the center of each light source is located on the same plane.
[0014] Furthermore, it also includes a secondary camera, which is fixedly connected to the outside of the housing via a rigid connecting tube I; the optical axes of each secondary camera and the main camera converge at a point on the surface of the object to be measured.
[0015] Furthermore, there are at least two secondary cameras. When there are two secondary cameras, they are equidistantly positioned on either side of the main camera. When there are multiple secondary cameras, they are positioned around the main camera.
[0016] Furthermore, protective covers are provided in front of the main camera and secondary camera lenses, with transparent glass at the front end of the protective covers to protect the camera lenses.
[0017] Furthermore, a cooling fan is also provided on the housing; a filter screen is provided on the side of the cooling fan facing the inner cavity of the housing.
[0018] Furthermore, the rigid connecting tube and the rigid connecting tube I are equipped with a flexible wire fixing structure for fixing the cables of each monochrome light source or secondary camera.
[0019] The beneficial effects of this invention are as follows: By arranging at least three monochromatic light sources of different colors, the same position of the object under test can be simultaneously illuminated by red, green, and blue light, thereby enabling the sensor to acquire multiple different defect feature information in a single imaging process. This reduces image interference, makes defects more obvious, and results in richer imaging information, clearer images, and faster detection speed. In addition, the cooperation of the main camera, light source group, and secondary camera meets the requirements for long working distance, large field of view, and multi-angle imaging. It enables low-exposure photography to avoid motion blur, and the large field of view reduces the number of shooting positions. It can simultaneously obtain multiple images of the object under test from different angles from a single detection viewpoint, reducing the number of shooting points required for a single camera and greatly saving time. Attached Figure Description
[0020] Figure 1 A schematic diagram of the structure of a surface defect detection sensor for die-cast parts provided by this utility model;
[0021] Figure 2 A schematic diagram of another surface defect detection sensor for die castings provided by this utility model;
[0022] Figure 3 A schematic diagram of a surface defect detection sensor for die-cast parts equipped with three auxiliary cameras provided by this utility model;
[0023] Figure 4 A schematic diagram showing the arrangement of multiple secondary cameras around the main camera;
[0024] Figure 5 A schematic diagram showing the arrangement when there are two secondary cameras;
[0025] Figure 6 This is a cross-sectional view of a rigid connecting pipe. Detailed Implementation
[0026] The technical solution of this utility model will be described in detail below with reference to the accompanying drawings and embodiments.
[0027] This utility model provides a surface defect detection sensor for die castings, used to detect surface defects in die-cast objects, including a main camera 2 and a light source group 3;
[0028] The light source group 3 includes at least three monochromatic light sources; the same test position of the object to be tested is located within the illumination area of at least three different monochromatic light sources, and the three different monochromatic light sources project red light, green light and blue light respectively;
[0029] The main camera 2 is a color camera, capable of acquiring individual images of the object under test against each monochromatic light source background and / or capable of acquiring mixed images of the object under test against at least three monochromatic light source backgrounds.
[0030] In some embodiments, since the object under test has just completed the die-casting process and still has a lot of residual heat, when conducting the test, it is necessary to maintain a certain safe distance between the testing device and the object under test. Therefore, the main camera 2 needs to be a color camera with a long working distance and a large field of view. For this reason, the monochromatic light source in the light source group 3 needs to be a high-power surface light source or a strip light source. Preferably, the power of the high-power surface light source or strip light source is not less than 200 watts.
[0031] In some embodiments, such as Figure 1As shown, the surface defect detection sensor for die-cast parts also includes a housing 1, with a main camera 2 and a light source group 3 embedded on one side of the housing 1. The image acquisition end of the main camera 2 and the light source emission end of the light source group 3 are exposed on the outside of the housing. Each monochromatic light source in the light source group 3 can be evenly distributed around the main camera 2 as the center.
[0032] Or, such as Figure 2 As shown, the main camera 2 is embedded in the housing 1, with its image acquisition end exposed on the outside of the housing 1; the light source group 3 is fixedly connected to the outside of the housing 1 through rigid connecting pipes 4. Each monochromatic light source in the light source group 3 can be evenly distributed around the optical axis of the main camera 2; preferably, the angle between the optical axis of the main camera 2 and the plane where each light source is located is the same, and the center of each light source is located on the same plane.
[0033] In some embodiments, such as Figure 3 As shown, the surface defect detection sensor for die-cast parts also includes a secondary camera 5, which is fixedly connected to the outside of the housing 1 via a rigid connecting pipe I 7; the optical axes of each secondary camera 5 and the optical axis of the main camera 2 converge at a point on the surface of the object to be measured.
[0034] In specific implementation, such as Figure 4 , Figure 5 As shown, there are at least two secondary cameras 5. When there are two secondary cameras 5, they are set at equal intervals on both sides of the main camera 2. The main camera captures the front image of the object to be tested, and the secondary camera captures the side image of the object to be tested from the side. This can realize the simultaneous acquisition of multiple images of the object to be tested from different angles at one shooting point, which greatly reduces the workload of detection and improves the cycle time.
[0035] When there are multiple secondary cameras 5, they are arranged around the main camera 2. The main camera captures the front image of the object under test, and the multiple secondary cameras 5 capture images of the part from multiple sides. At this time, the field of view of each secondary camera 5 can cover the entire object under test, so that the sensor can obtain multiple different defect feature information in one imaging.
[0036] In some embodiments, a protective cover 6 is provided in front of the lenses of the main camera 2 and the secondary camera 5, and a transparent glass is provided at the front end of the protective cover 6 to protect the camera lenses; preferably, the light transmittance of the transparent glass is greater than 90%.
[0037] In some embodiments, the housing 1 is further provided with a cooling fan 8 for dissipating heat from the entire device; the side of the cooling fan 8 facing the inner cavity of the housing is provided with a filter screen for blocking oil mist in the environment from entering the sensor through the cooling fan, thereby keeping the inside of the sensor clean.
[0038] In some embodiments, such as Figure 6As shown, the rigid connecting tube 4 and the rigid connecting tube I 7 are provided with a flexible wire fixing structure 9, which is used to fix the monochromatic light source or auxiliary camera cable passing through the rigid connecting tube 4 and the rigid connecting tube I 7.
[0039] This utility model discloses a surface defect detection sensor for die-cast parts, applicable to the following three motion detection states: 1. During detection, the object to be tested is fixed, and the surface defect detection sensor is fixed on a moving robotic arm or slide rail for detection; 2. During detection, the surface defect detection sensor is fixed, and the object to be tested is placed on a moving conveyor belt or robotic arm for detection; 3. During detection, the object to be tested is placed on a moving conveyor belt or robotic arm, and the surface defect detection sensor is fixed on a moving robotic arm or slide rail, both moving simultaneously for detection; When the surface defect detection sensor and the object to be tested move simultaneously for detection, they can be in a relatively stationary state or in a state of relative displacement.
[0040] This invention utilizes at least three monochromatic light sources of different colors to simultaneously illuminate the same location of the object under test with red, green, and blue light. This allows the sensor to acquire multiple different defect feature information in a single imaging process, reducing image interference, making defects more apparent, providing richer imaging information, clearer images, and faster detection speed. Furthermore, the cooperation of the main camera, light source group, and secondary camera meets the requirements for long working distance, large field of view, and multi-angle imaging. It enables low-exposure photography to avoid motion blur, and the large field of view reduces the number of shooting positions, allowing multiple images of the object under test from different angles to be obtained simultaneously from a single detection viewpoint. This reduces the number of shooting points required for a single camera and significantly saves time.
[0041] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and descriptive purposes. It is not intended to be exhaustive, nor to limit the invention to the precise forms disclosed; obviously, many changes and variations are possible in accordance with the foregoing teachings. The exemplary embodiments were chosen and described to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to implement and utilize various exemplary embodiments of the invention, as well as their different alternatives and modifications. The scope of the invention is intended to be defined by the appended claims and their equivalents.
Claims
1. A surface defect detection sensor for die-cast parts, used for detecting surface defects in die-cast objects, comprising a housing (1), a main camera (2), and a light source assembly (3); characterized in that: The light source group (3) includes at least three monochromatic light sources; the same test position of the object to be tested is located within the illumination area of at least three different monochromatic light sources, and the three different monochromatic light sources project red light, green light and blue light respectively; The main camera (2) is a color camera, capable of acquiring individual images of the object under test against each monochromatic light source background and / or capable of acquiring mixed images of the object under test against at least three monochromatic light source backgrounds; The main camera (2) and the light source group (3) are embedded on one side of the housing (1); each monochromatic light source in the light source group is evenly distributed around the main camera (2) as the center; Alternatively, the main camera (2) is embedded in the housing (1); the light source group (3) is fixedly connected to the outside of the housing (1) through rigid connecting tubes (4); each monochromatic light source in the light source group is evenly distributed around the optical axis of the main camera (2).
2. The die-casting surface defect detection sensor as described in claim 1, characterized in that: The monochromatic light source in the light source group (3) is a surface light source or a strip light source with a power of not less than 200 watts.
3. The surface defect detection sensor for die-cast parts as described in claim 1, characterized in that: When the main camera (2) is embedded in the housing (1) and the light source group (3) is fixedly connected to the outside of the housing (1) through rigid connecting tubes (4), each monochromatic light source in the light source group is evenly distributed around the optical axis of the main camera (2), the optical axis of the main camera (2) has the same angle with the plane where each light source is located, and the center of each light source is located on the same plane.
4. The die-casting surface defect detection sensor as described in any one of claims 1 to 3, characterized in that: It also includes a secondary camera (5), which is fixedly connected to the outside of the housing (1) through a rigid connecting tube I (7); the optical axis of each secondary camera (5) and the optical axis of the main camera (2) converge at a point on the surface of the object to be measured.
5. The die-casting surface defect detection sensor as described in claim 4, characterized in that: There are at least two secondary cameras (5). When there are two secondary cameras (5), they are equidistantly arranged on both sides of the main camera (2). When there are multiple secondary cameras (5), they are arranged around the main camera (2).
6. The die-casting surface defect detection sensor as described in claim 4, characterized in that: The main camera (2) and the secondary camera (5) are provided with protective covers (6) in front of their lenses. The front end of the protective cover (6) is provided with transparent glass to protect the camera lenses.
7. The die-casting surface defect detection sensor as described in claim 1, characterized in that: The housing (1) is also provided with a cooling fan (8); the cooling fan (8) has a filter screen on the side facing the inner cavity of the housing.
8. The die-casting surface defect detection sensor as described in claim 4, characterized in that: The rigid connecting pipe (4) and rigid connecting pipe I (7) are provided with a flexible wire fixing structure (9) for fixing the cables of each monochrome light source or secondary camera.