A machine vision-based surface defect detection system for die castings

Abstract

The application relates to the technical field of defect detection devices, in particular to a die casting surface defect detection system based on machine vision, which comprises a support, a rotating seat, a lifting block, a vision module and a light source, a depth detection mechanism is further arranged on the lifting block, the depth detection mechanism is inserted into the defect on the surface of the die casting through a probe, the probe is adhered with a chromogenic solution, then the length of the chromogenic solution adhered to the tip of the probe is detected through the vision module, and the defect depth on the surface of the die casting is detected; the probe and a rotating block are arranged on the lifting block, the probe is first inserted into the defect on the surface of the die casting, the probe is adhered with the chromogenic solution in the defect, then the probe is pulled out and rotated by 90 degrees, the part of the probe front end adhered with the chromogenic solution is displayed in front of the vision module, so that the vision module detects the distance of the chromogenic solution adhered to the probe front end, and the defect depth on the surface of the die casting is detected.

Description

Technical Field

[0001] This invention relates to the field of defect detection device technology, and in particular to a machine vision-based surface defect detection system for die-cast parts. Background Technology

[0002] Die casting, as an efficient and precise parts forming process, is widely used in the automotive, aerospace, and electronic communications industries. During the production process, die castings are prone to various defects on their surface, such as cold shuts, cracks, porosity, shrinkage cavities, undercasting, and scoring, due to fluctuations in process parameters, mold wear, or insufficient flow of liquid metal. These surface defects not only affect the appearance quality of the product but also seriously impair its mechanical properties and service life. Therefore, comprehensive surface quality inspection of die castings is necessary. Currently, more advanced enterprises use automated inspection technology based on machine vision. However, the surface of castings often has high reflectivity, which causes light spots or shadows in the image. Therefore, colorants are used to penetrate and press into the defects on the surface of the castings, and the colorants are used to enhance the color and highlight the defects, thereby improving the inspection effect of machine vision. Colorants are used to highlight defects on the surface of die-cast parts. Machine vision can only detect the location, size, and shape of defects on the surface of die-cast parts, but cannot detect the depth of defects, thus causing limitations.

[0003] To address this, we propose a machine vision-based surface defect detection system for die-cast parts. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a machine vision-based surface defect detection system for die-cast parts, which overcomes the deficiencies of existing technologies and aims to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a machine vision-based surface defect detection system for die-cast parts, comprising: The system comprises a bracket, a rotating base, a lifting block, a vision module, and a light source. The rotating base is rotatably connected to the bracket, and the lifting block is slidably connected to the rotating base. The vision module and the light source are both mounted on the lifting block. A ring gear is mounted on the bracket. A rotary motor is mounted on the rotating base, and a gear that meshes with the ring gear is mounted on the output end of the rotary motor. A lifting motor is mounted on the rotating base, and a lead screw that is threaded into the lifting block is mounted on the output end of the lifting motor. The lifting block is also equipped with a depth detection mechanism. The depth detection mechanism inserts a probe into the defect on the surface of the die-casting part, allows the probe to adhere to the color developer, and then uses the vision module to detect the length of the color developer adhering to the probe tip to detect the depth of the defect on the surface of the die-casting part.

[0006] Preferably, the depth detection mechanism includes a telescopic block, a rotating block, and a probe. The telescopic block is slidably connected to the lifting block, and a telescopic electric push rod is connected between the telescopic block and the lifting block. The rotating block is rotatably connected to the telescopic block, and a rotating gear ring is installed on the rotating block. A rotating motor is installed on the telescopic block, and a gear that meshes with the rotating gear ring is installed at the output end of the rotating motor. A mounting block is installed on the rotating block, and the probe is mounted on the mounting block.

[0007] Preferably, a piezoelectric ceramic actuator is installed inside the rotating block, the mounting block is slidably engaged with the rotating block, and the piezoelectric ceramic actuator is in contact with the mounting block.

[0008] Preferably, a sliding block is slidably connected to the lifting block, and a sliding electric push rod is connected between the sliding block and the lifting block. A cleaning cylinder is installed on the sliding block, and cleaning ports are evenly arranged inside the cleaning cylinder. A cleaning interface is provided on the cleaning cylinder, and the cleaning interface is connected to a water pipe and an air pipe. An adsorption ring is fixedly connected to the cleaning cylinder, and a magnet is installed inside the adsorption ring. A discharge port is provided on the cleaning cylinder for discharging the cleaned water.

[0009] By setting a probe and a rotating block on the mounting block, the probe is first inserted into the defect on the surface of the die casting, and the probe is coated with the coloring liquid inside the defect. Then the probe is pulled out and rotated 90 degrees to display the part of the probe tip with the coloring liquid in front of the vision module. The vision module can then detect the distance of the coloring liquid adhering to the probe tip, thereby detecting the depth of the defect on the surface of the die casting.

[0010] Preferably, the probe tip is bent and the probe tip is stepped.

[0011] Preferably, the probe has a liquid replenishment channel, a communication interface connected to the liquid replenishment channel, a connecting ring fixedly connected to the probe, a sliding ring slidably fitted on the probe, a capacitor electrode mounted on the sliding ring, and the capacitor electrode surrounding the probe.

[0012] Preferably, a sliding rod is slidably connected to the connecting ring, the sliding ring and the sliding rod are fixedly connected, the connecting ring and the sliding rod are fixed by friction, and the end of the sliding rod away from the sliding ring is T-shaped to prevent the sliding rod from detaching from the connecting ring.

[0013] Preferably, the mounting block is also provided with an exhaust needle, which has the same structure as the probe. The exhaust needle is also provided with a communication interface, which is connected to a negative pressure air source to generate negative pressure.

[0014] By setting a sliding ring and a capacitive electrode on the probe, the probe is used to fill the defects on the surface of the die casting with coloring liquid. This ensures that the coloring liquid inside the defect does not dry out, preventing the distance of the coloring liquid adhering to the probe surface from being shorter than the actual depth of the defect. At the same time, the capacitive electrode detects that the liquid level of the coloring liquid is flush with the surface of the die casting, ensuring that the depth of the coloring liquid is the same as the depth of the defect on the surface of the die casting.

[0015] The beneficial effects of this invention are: 1. The present invention sets a probe and a rotating block on the lifting block. First, the probe is inserted into the defect on the surface of the die casting and the probe is coated with the coloring liquid in the defect. Then the probe is pulled out and rotated 90 degrees to display the part of the probe tip coated with the coloring liquid in front of the vision module. The vision module detects the distance of the coloring liquid adhering to the probe tip, thereby detecting the depth of the defect on the surface of the die casting.

[0016] 2. This invention uses a sliding ring and a capacitive electrode on a probe to fill the defects on the surface of the die-casting with a color-developing liquid. This ensures that the color-developing liquid inside the defect does not dry out, preventing the distance of the color-developing liquid adhering to the probe surface from being shorter than the actual depth of the defect. At the same time, the capacitive electrode detects that the liquid level of the color-developing liquid is flush with the surface of the die-casting, ensuring that the depth of the color-developing liquid is the same as the depth of the defect on the surface of the die-casting. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 for Figure 1 Enlarged view of point A in the middle; Figure 3 for Figure 1 Enlarged view of point B in the middle; Figure 4 for Figure 2 Enlarged view of point C in the middle; Figure 5 This is a partial cross-sectional view of the cleaning cylinder and adsorption ring of the present invention; Figure 6 This is a schematic diagram showing the positional relationship of the rotating block, mounting block, and piezoelectric ceramic actuator in cross-section in this invention.

[0018] In the diagram: 1. Bracket; 11. Rotating seat; 12. Lifting block; 13. Vision module; 14. Light source; 15. Ring gear ring; 16. Rotary motor; 17. Lifting motor; 21. Telescopic block; 22. Rotating block; 23. Probe; 24. Mounting block; 25. Piezoelectric ceramic actuator; 3. Liquid replenishment channel; 31. Connecting ring; 32. Sliding ring; 33. Capacitor electrode; 34. Sliding rod; 4. Exhaust needle; 41. Connecting interface; 5. Sliding block; 51. Cleaning cylinder; 52. Cleaning port; 53. Cleaning interface; 6. Telescopic electric push rod; 61. Rotary motor; 62. Rotating gear ring; 7. Adsorption ring; 71. Magnet block; 8. Sliding electric push rod; 9. Discharge port. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Refer to the appendix of the instruction manual. Figures 1 to 6 A machine vision-based surface defect detection system for die-cast parts includes: The system includes a bracket 1, a rotating seat 11, a lifting block 12, a vision module 13, and a light source 14. The rotating seat 11 is rotatably connected to the bracket 1, and the lifting block 12 is slidably connected to the rotating seat 11. The vision module 13 and the light source 14 are both mounted on the lifting block 12. A ring gear 15 is mounted on the bracket 1. A rotary motor 16 is mounted on the rotating seat 11. A gear that meshes with the ring gear 15 is mounted on the output end of the rotary motor 16. A lifting motor 17 is mounted on the rotating seat 11. A lead screw that is threadedly engaged with the lifting block 12 is mounted on the output end of the lifting motor 17. The lifting block 12 is also equipped with a depth detection mechanism. The depth detection mechanism inserts a probe 23 into the defect on the surface of the die casting, allows the probe 23 to adhere to the color developer, and then uses the vision module 13 to detect the length of the color developer adhering to the tip of the probe 23, thereby detecting the depth of the defect on the surface of the die casting.

[0021] In this invention, the depth detection mechanism includes a telescopic block 21, a rotating block 22, and a probe 23. The telescopic block 21 is slidably connected to the lifting block 12, and a telescopic electric push rod 6 is connected between the telescopic block 21 and the lifting block 12. The rotating block 22 is rotatably connected to the telescopic block 21, and a rotating gear ring 62 is installed on the rotating block 22. A rotating motor 61 is installed on the telescopic block 21, and a gear that meshes with the rotating gear ring 62 is installed at the output end of the rotating motor 61. An mounting block 24 is installed on the rotating block 22, and the probe 23 is installed on the mounting block 24.

[0022] In this invention, a piezoelectric ceramic actuator 25 is installed inside the rotating block 22, the mounting block 24 is slidably engaged with the rotating block 22, and the piezoelectric ceramic actuator 25 is in contact with the mounting block 24.

[0023] In this invention, a sliding block 5 is slidably connected to the lifting block 12, and a sliding electric push rod 8 is connected between the sliding block 5 and the lifting block 12. A cleaning cylinder 51 is installed on the sliding block 5, and cleaning ports 52 are evenly arranged inside the cleaning cylinder 51. A cleaning interface 53 is provided on the cleaning cylinder 51, and the cleaning interface 53 is connected to a water pipe and an air pipe. The water pipe and the air pipe are controlled separately by valves. An adsorption ring 7 is fixedly connected to the cleaning cylinder 51, and a magnet block 71 is installed inside the adsorption ring 7. A discharge port 9 is provided on the cleaning cylinder 51, and the discharge port 9 is used to discharge the water after cleaning.

[0024] In this invention, after the die-casting part is immersed in the color developing solution, it is taken out. When there are defects such as cracks or pits on the surface of the die-casting part, the color developing solution will enter the cracks or pits and fill them under the action of liquid surface tension. Then, the die-casting part is transported by a conveyor belt and other conveying equipment to the area below the support 1. The rotary motor 16 drives the corresponding gear to rotate, so that the rotating seat 11 rotates along the support 1. Thus, the rotating seat 11, the vision module 13, and the light source 14 rotate around the die-casting part. The lifting motor 17 drives the corresponding lead screw to rotate, so that the lifting block 12 moves up and down with the vision module 13 and the light source 14. Thus, the vision module 13 and the light source 14 of this invention rotate around the die-casting part to scan the surface image of the die-casting part and detect whether there are obvious traces of color developing solution. When traces of developing liquid are detected on the surface of the die-casting, the telescopic electric push rod 6 pushes the telescopic block 21, and at the same time the lifting block 12 moves to adjust the position of the probe 23 on the telescopic block 21 until the probe 23 coincides with the defect area on the surface of the die-casting. The probe 23 extends into the crack or pit under the drive of the telescopic block 21. The developing liquid in the crack or pit adheres to the front end of the probe 23. After the probe 23 contacts the die-casting, the piezoelectric ceramic actuator 25 is subjected to pressure and generates current, thereby detecting the contact between the probe 23 and the die-casting. Then the probe 23 is pulled out of the crack or pit, and the rotating motor 61 drives the corresponding gear to rotate, so that the rotating block 22 carries the probe 23 to rotate laterally. The part of the probe 23 with developing liquid adhering to its front end appears in front of the vision module 13. The vision module 13 detects the distance of the developing liquid adhering to the probe 23, thereby detecting the depth of the crack or pit on the surface of the die-casting. In this invention, the probe 23 is made of elastic material and is a small needle shape. Most of the defects on the surface of the die casting are cracks or pores perpendicular to the surface of the die casting. Therefore, the small probe 23 can be inserted vertically into the cracks or pores on the surface of the die casting to detect the depth of the defects on the surface of the die casting. In this invention, after the vision module 13 completes the detection, the sliding electric push rod 8 drives the sliding block 5 and the cleaning cylinder 51 to move towards the probe 23, so that the cleaning cylinder 51 is fitted over the probe 23. Then, water is sprayed out from the cleaning port 52 through the cleaning interface 53 to wash away the color developing liquid adhering to the surface of the probe 23. The water in the cleaning cylinder 51 that washes the probe 23 is discharged from the outlet 9. Then, high-pressure air enters the cleaning port 52 from the cleaning interface 53, and the air sprayed out from the cleaning port 52 blows away the water stains remaining on the surface of the probe 23, thereby completing the cleaning of the probe 23. In this invention, by setting a probe 23 and a rotating block 22 on the lifting block 12, the probe 23 first extends into the defect on the surface of the die-casting part, and the probe 23 adheres to the coloring liquid in the defect. Then, the probe 23 is pulled out and rotated 90 degrees, so that the part of the probe 23 with the coloring liquid adhering to the front end is displayed in front of the vision module 13. Thus, the vision module 13 detects the distance of the coloring liquid adhering to the front end of the probe 23, thereby detecting the depth of the defect on the surface of the die-casting part.

[0025] Example 2: Based on Example 1, refer to the appendix of the instruction manual. Figures 1 to 6 In this invention, the front end of the probe 23 is bent and the front end of the probe 23 is stepped.

[0026] In this invention, a liquid replenishment channel 3 is provided on the probe 23, and a communication interface 41 is provided on the probe 23 to communicate with the liquid replenishment channel 3. A connecting ring 31 is fixedly connected to the probe 23, and a sliding ring 32 is slidably fitted on the probe 23. A capacitor electrode 33 is installed on the sliding ring 32 and is arranged around the probe 23.

[0027] In this invention, a sliding rod 34 is slidably connected to the connecting ring 31, and the sliding ring 32 is fixedly connected to the sliding rod 34. The connecting ring 31 and the sliding rod 34 are fixed by friction. The end of the sliding rod 34 away from the sliding ring 32 is set in a T-shape to prevent the sliding rod 34 from detaching from the connecting ring 31.

[0028] In this invention, the mounting block 24 is also provided with an exhaust needle 4. The exhaust needle 4 has the same structure as the probe 23. The exhaust needle 4 is also provided with a communication interface 41. The communication interface 41 on the exhaust needle 4 is connected to a negative pressure air source, and negative pressure is generated through the negative pressure air source.

[0029] In this invention, the front end of the probe 23 is bent into a stepped shape, so that the front end of the probe 23 remains horizontal and exposed to the mounting block 24. In this way, the vision module 13 observes the horizontal part of the front end of the probe 23 as a point. The vision module 13 locates the horizontal and vertical positions of the front end of the probe 23 based on the position of this point, so that the control of the movement position of the probe 23 is more accurate. In this invention, the probe 23 is configured as a tubular structure, and its other end can be connected to a pipe. The pipe fills the replenishment channel 3 with color-developing liquid, thus replenishing the color-developing liquid within the defects on the surface of the die-casting after the probe 23 is inserted. A sliding ring 32 is slidably connected to the probe 23. When the probe 23 is inserted into the defects on the surface of the die-casting, the sliding ring 32 contacts the surface of the die-casting. When the level of the color-developing liquid within the defects rises to be flush with the surface of the die-casting, the capacitive electrode 33 on the sliding ring 32 contacts the color-developing liquid. When touched, they are interconnected and can conduct current through the color developing solution. This method is used to detect whether the liquid level of the color developing solution is flush with the surface of the die casting, thereby ensuring that the depth of the color developing solution is the same as the depth of the defects on the surface of the die casting after adding the color developing solution. When cleaning the probe 23, the magnet 71 in the adsorption ring 7 on the cleaning cylinder 51 will attract the sliding ring 32 made of metal. When the probe 23 is pulled away from the cleaning cylinder 51, the sliding ring 32 can move to the front end of the probe 23 under the action of the magnet 71, and finally detach from the magnet 71 under the pull of the sliding rod 34. In this invention, an exhaust pin 4 is provided on the mounting block 24. The exhaust pin 4 is located below the probe 23 and is inserted into the defect on the surface of the die casting along with the probe 23. It is connected to the negative pressure source through the connecting interface 41 to generate a small negative pressure, thus drawing a certain amount of color developing liquid into the exhaust pin 4. If the color developing liquid contains air bubbles, the air bubbles are drawn into the exhaust pin 4 along with the color developing liquid. The liquid replenishment channel 3 continuously fills the defect on the surface of the die casting with color developing liquid until the liquid level is flush with the surface of the die casting. This invention provides a sliding ring 32 and a capacitor electrode 33 on a probe 23. The probe 23 is used to fill the defects on the surface of the die-casting with a color-developing liquid, ensuring that the color-developing liquid inside the defects does not dry out and preventing the distance of the color-developing liquid adhering to the surface of the probe 23 from being shorter than the actual depth of the defects. At the same time, the capacitor electrode 33 detects that the liquid level of the color-developing liquid is flush with the surface of the die-casting, ensuring that the depth of the color-developing liquid is the same as the depth of the defects on the surface of the die-casting.

[0030] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A machine vision-based surface defect detection system for die-cast parts, characterized in that: The device includes a bracket (1), a rotating seat (11), a lifting block (12), a vision module (13), and a light source (14). The rotating seat (11) is rotatably connected to the bracket (1), and the lifting block (12) is slidably connected to the rotating seat (11). The vision module (13) and the light source (14) are both mounted on the lifting block (12). A ring gear (15) is mounted on the bracket (1). A rotary motor (16) is provided on the rotating seat (11). A gear that meshes with the ring gear (15) is installed at the output end of the rotary motor (16). A lifting motor (17) is mounted on the rotating seat (11). A lead screw that is threadedly engaged with the lifting block (12) is installed at the output end of the lifting motor (17). The lifting block (12) is also equipped with a depth detection mechanism. The depth detection mechanism inserts a probe (23) into the defect on the surface of the die casting, allows the probe (23) to adhere to the color developer, and then uses the vision module (13) to detect the length of the color developer adhering to the tip of the probe (23) to detect the depth of the defect on the surface of the die casting. The depth detection mechanism includes a telescopic block (21), a rotating block (22), and a probe (23). The telescopic block (21) is slidably connected to the lifting block (12). A telescopic electric push rod (6) is connected between the telescopic block (21) and the lifting block (12). The rotating block (22) is rotatably connected to the telescopic block (21). A rotating gear ring (62) is installed on the rotating block (22). A rotating motor (61) is installed on the telescopic block (21). A gear that meshes with the rotating gear ring (62) is installed at the output end of the rotating motor (61). A mounting block (24) is installed on the rotating block (22). The probe (23) is installed on the mounting block (24). A piezoelectric ceramic actuator (25) is installed inside the rotating block (22), the mounting block (24) is slidably engaged with the rotating block (22), and the piezoelectric ceramic actuator (25) is in contact with the mounting block (24); A sliding block (5) is slidably connected to the lifting block (12). A sliding electric push rod (8) is connected between the sliding block (5) and the lifting block (12). A cleaning cylinder (51) is installed on the sliding block (5). Cleaning ports (52) are evenly arranged inside the cleaning cylinder (51). A cleaning interface (53) is provided on the cleaning cylinder (51). The cleaning interface (53) is connected to a water pipe and an air pipe. An adsorption ring (7) is fixedly connected to the cleaning cylinder (51). A magnet block (71) is installed inside the adsorption ring (7). A discharge port (9) is provided on the cleaning cylinder (51). The discharge port (9) is used to discharge the water after cleaning.

2. The machine vision-based surface defect detection system for die-cast parts according to claim 1, characterized in that: The probe (23) has a bent front end, and the front end of the probe (23) is stepped.

3. The machine vision-based surface defect detection system for die-cast parts according to claim 2, characterized in that: The probe (23) has a liquid replenishment channel (3), and the probe (23) has a communication interface (41) connected to the liquid replenishment channel (3). A connecting ring (31) is fixedly connected to the probe (23), and a sliding ring (32) is slidably fitted on the probe (23). A capacitor electrode (33) is installed on the sliding ring (32), and the capacitor electrode (33) is arranged around the probe (23).

4. The machine vision-based surface defect detection system for die-cast parts according to claim 3, characterized in that: A sliding rod (34) is slidably connected to the connecting ring (31). The sliding ring (32) is fixedly connected to the sliding rod (34). The connecting ring (31) and the sliding rod (34) are fixed by friction. The end of the sliding rod (34) away from the sliding ring (32) is set in a T-shape to prevent the sliding rod (34) from detaching from the connecting ring (31).

5. The machine vision-based surface defect detection system for die-cast parts according to claim 4, characterized in that: The mounting block (24) is also provided with an exhaust pin (4), which has the same structure as the probe (23). The exhaust pin (4) is also provided with a communication interface (41), which is connected to a negative pressure air source. The negative pressure is generated by the negative pressure air source to prevent air bubbles from being contained in the surface defects of the die-casting part, thus affecting the actual detection depth.

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