Automatic optical detection machine for bottle preform detection

Abstract

The invention belongs to the technical field of optical detection technology and automatic manufacturing equipment, and discloses an automatic optical detection machine for bottle preform detection, which comprises a frame as a shell of the automatic optical detection machine; the conveying belt is fixedly mounted in the frame and is used for conveying bottle blanks; the shooting assembly is installed on the frame, distributed around the conveying belt and used for shooting bottle preforms on the conveying belt; the press-fit type stable structure comprises a mounting frame, a positioning plate, a pressing plate, a perforated plate, a transparent plate, a negative pressure adsorption structure and a magnetic attraction driving structure; the mechanical press-fit acts first, so that the six-degree-of-freedom shaking of the bottle preform is quickly eliminated, and an absolutely static shooting target is provided for a camera; the negative pressure adsorption is then enhanced, vibration and impact are resisted by increasing the friction force between the bottle preform and the conveying belt, the problems of image blurring and smear caused by shaking are thoroughly solved through combination of the negative pressure adsorption and the conveying belt, and the detection precision is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of optical inspection technology and automated manufacturing equipment technology, and particularly relates to an automatic optical inspection machine for preform inspection. Background Technology

[0002] As an intermediate product in the blown beverage bottle manufacturing process, the quality of ET preforms directly determines the quality of the final product. During production, preforms may exhibit dimensional defects (such as incorrect inner diameter, height, and wall thickness), appearance defects (such as cracks, bubbles, black spots, and stains), and structural defects (such as broken mouths, missing threads, and bottom misalignment). Therefore, conducting 100% inspection of preforms before shipment is a crucial step in ensuring product quality. Automated Optical Inspection (AOI) machines have become standard equipment on preform production lines due to their high efficiency, high precision and non-contact characteristics. Their working principle is as follows: preforms are sent to the inspection area by a vibratory feeder or conveyor belt, an industrial camera acquires images of the preforms under the illumination of a specific light source, the image processing system analyzes the images through algorithms and compares them with preset standards to determine whether the products are qualified or not, and finally the defective products are removed by the rejection device. However, existing preform AOI equipment still suffers from a long-standing technical challenge in practical applications: the stability of the preform during the inspection process, specifically manifested as follows: Dynamic shaking causes image blurring: To ensure production efficiency, preforms are usually inspected on a continuously running conveyor belt. The vibration of the conveyor belt, the cumulative error of the chain pitch, and the tiny gap between the preform and the conveyor belt can all cause the preform to have a tiny displacement or shaking at the moment of imaging. For area scan cameras with extremely high shooting frequency or line scan cameras that perform continuous scanning, this shaking will cause image blurring, ghosting, or geometric distortion, which will seriously affect the judgment accuracy of the detection algorithm and cause false detection or missed detection. Summary of the Invention

[0003] This invention addresses the problem that in existing technologies, bottle preforms are typically inspected on a continuously running conveyor belt. Conveyor belt vibration, cumulative chain pitch errors, and minute gaps between the preform and the conveyor belt all cause slight displacement or shaking of the preform during imaging. For high-frequency area scan cameras or continuous scanning line scan cameras, this shaking leads to image blurring, ghosting, or geometric distortion, severely affecting the accuracy of the detection algorithm and causing false positives or false negatives. The invention proposes the following technical solution: An automated optical inspection machine for preform inspection includes: a frame, which serves as the housing of the automated optical inspection machine; A conveyor belt, fixedly installed inside the frame, transports bottle preforms; A camera assembly, mounted on the frame and distributed around the conveyor belt, is used to photograph preforms on the conveyor belt. The press-fit stabilizing structure includes a mounting bracket, positioning plate, pressure plate, perforated plate, transparent plate, negative pressure adsorption structure, and magnetic drive structure; Mounting bracket, fixedly installed above the conveyor belt; The positioning plate is fixedly installed on one end face of the mounting bracket; A magnetic drive structure is disposed between the positioning plate and the pressure plate, for driving the pressure plate to move closer to or away from the conveyor belt relative to the mounting frame; The pressure plate is fixedly connected to the magnetic drive structure; The perforated plate is fixedly connected below the pressure plate and located above the conveyor belt, for contacting the preform. A transparent plate is placed on the end face of the pressure plate near the shooting component and located below the shooting component; A negative pressure adsorption structure is disposed inside the positioning plate and the mounting frame and is connected to the perforated plate. It is used to drive the gas to flow along the outside of the preform and to adsorb the preform using negative pressure.

[0004] As a preferred embodiment of the above technical solution, the positioning plate has four integrally formed support feet at its bottom corners, and sleeves are fitted onto the outer sides of the support feet. The sleeves are fixedly installed above the pressure plate, and sealing rings are snapped onto the outer sides of the support feet.

[0005] As a preferred embodiment of the above technical solution, the magnetic drive structure includes an electromagnetic adsorption structure, which is snapped into the inside of the support foot. A return spring is fixedly connected to the bottom of the electromagnetic adsorption structure, and a magnetic adsorption structure is fixedly installed at the bottom of the return spring. The end of the magnetic adsorption structure away from the return spring is fixedly installed inside the pressure plate. Multiple support columns are embedded in the top of the pressure plate at the middle position of the magnetic adsorption structure, and the tops of the multiple support columns are snapped together with the same piston.

[0006] As a preferred embodiment of the above technical solution, the pressure plate has a cavity inside, an air inlet is provided at the top of the pressure plate, a circular hole is provided inside the support foot, a connecting hole is provided at the bottom of the circular hole corresponding to the top of the pressure plate, the piston is conical in shape, and the maximum diameter of the piston is greater than the outer diameter of the circular hole.

[0007] As a preferred embodiment of the above technical solution, a cylinder is fixedly installed on the top of the positioning plate. The cylinder is connected to the circular hole inside the support foot through a pipe. A negative pressure fan is installed on the top of the cylinder by screws. A filter structure is installed on the top of the negative pressure fan by screws. A flow guide hood is installed on the top of the filter structure by screws. Three flow guide pipes are embedded in the top of the flow guide hood. The air inlet end of the flow guide pipe is located inside the flow guide hood. The three flow guide pipes are connected by the same air outlet plate.

[0008] As a preferred embodiment of the above technical solution, the outer side of the cylinder is symmetrically provided with rectangular holes, the top of the pressure plate is symmetrically embedded with baffles, the inner wall of the baffles and the outer side of the cylinder are in close contact with each other, and one end face of the baffles is provided with a guide hole.

[0009] As a preferred embodiment of the above technical solution, the perforated plate is specifically an open-cell silicone foam board, and the transparent plate is specifically an acrylic board.

[0010] As a preferred embodiment of the above technical solution, the vent plate has an exhaust hole inside, the exhaust hole is conical in shape, and the end of the exhaust hole inside the vent plate that is closer to the transparent plate is smaller than the other end.

[0011] As a preferred embodiment of the above technical solution, the electromagnetic adsorption structure specifically belongs to an electromagnet, and the magnetic adsorption structure specifically belongs to a permanent magnet.

[0012] The beneficial effects of this invention are as follows: (1) Mechanical pressing takes the lead in quickly eliminating the six degrees of freedom of the preform and providing the camera with an absolutely stationary shooting target; negative pressure adsorption is then enhanced, which resists vibration and impact by increasing the friction between the preform and the conveyor belt. The combination of the two completely solves the problem of image blurring and ghosting caused by shaking, and greatly improves the detection accuracy. (2) The negative pressure adsorption airflow can effectively remove dust from the surface of the preform while stabilizing the preform, avoiding misjudgment. The unique air path design can automatically switch to cleaning mode after the pressure plate is reset, and use pressurized airflow to blow the transparent plate and the bottom of the pressure plate to keep the optical window clean and reduce the frequency of manual maintenance. Attached Figure Description

[0013] Figure 1 The diagram shown is a schematic of an automated optical inspection machine for preform inspection in Example 1; Figure 2 The diagram shown is a schematic of the installation structure of the conveyor belt in Embodiment 1; Figure 3 The diagram shown is a schematic of the installation structure of the pressure plate in Embodiment 1; Figure 4 The diagram shown is a cross-sectional view of the baffle in Embodiment 1; Figure 5 The diagram shown is a cross-sectional view of the sleeve in Embodiment 1; Figure 6 The diagram shown is a schematic of the installation structure of the perforated plate in Embodiment 1; Figure 7 The diagram shown is a schematic of the installation structure of the return spring in Embodiment 1; Figure 8The image shown is a physical diagram of an automated optical inspection machine for preform inspection according to Example 1.

[0014] In the diagram: 1. Frame; 2. Conveyor belt; 3. Camera assembly; 41. Mounting bracket; 42. Positioning plate; 43. Sleeve; 44. Pressure plate; 45. Perforated plate; 46. Transparent plate; 47. Cylinder; 48. Negative pressure fan; 49. Filter structure; 410. Drainage hood; 411. Drainage pipe; 412. Air outlet plate; 413. Electromagnetic adsorption structure; 414. Return spring; 415. Magnetic adsorption structure; 416. Support column; 417. Piston; 418. Baffle; 419. Support foot. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0016] Example 1 This invention provides an automated optical inspection machine for preform inspection, such as... Figures 1 to 8 As shown, the system includes: a frame 1, a conveyor belt 2, a camera assembly 3, and a pressing-type stabilizing structure, serving as the housing of an automatic optical inspection machine. The conveyor belt 2 is fixedly installed inside the frame 1 and transports preforms. The camera assembly 3 is installed on the frame 1 and distributed around the conveyor belt 2 for photographing the preforms on the conveyor belt 2. It includes four sets of industrial cameras and a ring LED light source, all installed on the frame 1 and distributed around the conveyor belt 2. Two sets of cameras are horizontally symmetrically arranged on both sides of the conveyor belt 2 (corresponding to preform sidewall detection), one set of cameras is vertically arranged directly above the conveyor belt 2 (corresponding to preform top detection), and one set of cameras is tilted at the feed end of the conveyor belt 2 (corresponding to preform bottom detection). The ring LED light source corresponds to each camera, with a wavelength of 550-650nm, and the light intensity can be dynamically adjusted according to the preform transparency. The pressing-type stabilizing structure includes a mounting frame 41, a positioning plate 42, and a pressure plate 44. The system comprises: a perforated plate 45, a transparent plate 46, a negative pressure adsorption structure, and a magnetic drive structure; a mounting frame 41, fixedly mounted above the conveyor belt 2; a positioning plate 42, fixedly mounted on one end face of the mounting frame 41; a magnetic drive structure, located between the positioning plate 42 and the pressure plate 44, used to drive the pressure plate 44 to move closer to or further away from the conveyor belt 2 relative to the mounting frame 41; the pressure plate 44, fixedly connected to the magnetic drive structure; a perforated plate 45, fixedly connected below the pressure plate 44 and located above the conveyor belt 2, used to contact the preform; a transparent plate 46, located on one end face of the pressure plate 44 near the imaging component 3 and located below the imaging component 3; and a negative pressure adsorption structure, located inside the positioning plate 42 and the mounting frame 41, and connected to the perforated plate 45, used to drive gas to flow along the outside of the preform and to adsorb the preform using negative pressure. The perforated plate 45 is specifically an open-cell silicone foam board, and the transparent plate 46 is specifically an acrylic plate.

[0017] In the existing technology, the preform is detected on a continuously running conveyor belt 2. The vibration of the conveyor belt 2, the cumulative error of the chain pitch, and the tiny gap between the preform and the conveyor belt 2 will cause the preform to have a tiny displacement or shaking at the moment of imaging. For area scan cameras with extremely high shooting frequency or line scan cameras that perform continuous scanning, this shaking will cause image blurring, ghosting or geometric distortion, which will seriously affect the judgment accuracy of the detection algorithm and cause false detection or missed detection. This invention first overcomes the main shaking of the preform through a mechanical pressing mechanism, making it instantly stable; then, it provides a continuous stabilizing force through negative pressure adsorption to resist minor vibrations during the conveying process. This "active and passive combination" method achieves extremely high imaging stability without affecting the continuous operation of the production line. At the same time, the entire system uses the same negative pressure air source to achieve both adsorption stabilization and online cleaning functions.

[0018] During use, the conveyor belt 2 transports the preforms. At this time, the inspection station drives the pressure plate 44 downward through the magnetic drive structure, so that the perforated plate 45 contacts the mouth of the preform and applies gentle pressure. This action firstly eliminates the gap and relative movement between the preform and the conveyor belt 2 through mechanical pressing, fundamentally suppressing the six degrees of freedom sway of the preform at the moment of imaging (including movement and rotation in the forward, backward, left, right, up and down directions). This provides the industrial cameras above and to the side with a nearly absolutely stationary shooting target, thereby completely avoiding image blur, ghosting and geometric distortion. It provides high-quality and highly consistent original images for the back-end image processing algorithm, and greatly reduces the false detection and false detection rates. Next, the negative pressure adsorption structure operates. At this time, the airflow generates adsorption force through the porous structure of the perforated plate 45. This adsorption force further adsorbs the preform, increasing the positive pressure between the preform and the conveyor belt 2, thereby greatly increasing the static friction between them. This increased friction can effectively resist the vibration and minor impact generated during the operation of the conveyor belt 2. Since the adsorption force is vertical, it does not interfere with the normal flow of the preform along the conveyor belt 2 in the horizontal direction. Therefore, while obtaining super stability, the preform can still move smoothly along the direction set by the conveyor belt 2, achieving the ideal effect of "stable without stopping". It perfectly balances detection accuracy and production efficiency. Furthermore, under the action of the transparent plate 46, this structure does not affect the imaging component 3 above from taking pictures of the preform.

[0019] To achieve the goal of ensuring smooth movement of the pressure plate 44 and preventing deflection during its movement, as described in the above example, the following solution is provided: Figure 5 and Figure 7As shown, the four corners of the bottom of the positioning plate 42 are integrally formed with support feet 419. A sleeve 43 is sleeved on the outside of the support feet 419. The sleeve 43 is fixedly installed above the pressure plate 44. A sealing ring is snapped on the outside of the support feet 419. When in use, the pressure plate 44 moves along the outside of the support foot 419 through the sleeve 43. At this time, the pressure plate 44 moves smoothly downward under the combined action of the support foot 419 and the sleeve 43. At the same time, under the action of the sealing ring, the gas leakage is prevented from occurring at the connection between the sleeve 43 and the support foot 419, ensuring that the negative pressure adsorption structure can form a stable pressure field and provide airtightness guarantee for dual stability. To achieve the goal of moving the pressure plate 44 as described above, and then resetting it after movement, the following solution is provided: Figure 4 , Figure 5 and Figure 7 As shown, the magnetic drive structure includes an electromagnetic adsorption structure 413, which is snapped into the support foot 419. A return spring 414 is fixedly connected to the bottom of the electromagnetic adsorption structure 413. A magnetic adsorption structure 415 is fixedly installed at the bottom of the return spring 414. The end of the magnetic adsorption structure 415 away from the return spring 414 is fixedly installed inside the pressure plate 44. Multiple support columns 416 are embedded in the top of the pressure plate 44 at the middle position of the magnetic adsorption structure 415. There are three support columns 416 in total, arranged in a triangular array. The tops of the multiple support columns 416 are snapped together with the same piston 417. The electromagnetic adsorption structure 413 is specifically an electromagnet, and the magnetic adsorption structure 415 is specifically a permanent magnet.

[0020] When in use, the electromagnetic adsorption structure 413 is energized, generating a magnetic field. The magnetic field generated by the electromagnetic adsorption structure 413 during operation is opposite to the magnetic poles of the opposite side of the magnetic adsorption structure 415, thereby driving the magnetic adsorption structure 415 to move. When the magnetic adsorption structure 415 moves, it drives the sleeve 43 to move. When the sleeve 43 moves, it drives the pressure plate 44 to descend. At the same time, the piston 417 is driven to descend by the support column 416, and the return spring 414 is stretched. At this time, the piston 417 descends and disengages from the round hole of the support leg 419, providing conditions for the air passage to be opened for negative pressure adsorption, realizing the linkage of "mechanical pressing in place and air passage opening", ensuring dual stable timing coordination. Furthermore, in order to allow the gas to flow, a cavity is provided inside the pressure plate 44, an air inlet is provided at the top of the pressure plate 44, a round hole is provided inside the support foot 419, a connecting hole is provided at the bottom of the round hole corresponding to the top of the pressure plate 44, and the piston 417 is conical in shape, with the maximum diameter of the piston 417 being greater than the outer diameter of the round hole. In use, gas enters the cavity of pressure plate 44 along the perforated plate 45, and then enters the sleeve 43 along the cavity of pressure plate 44. Finally, it enters the support foot 419 along the sleeve 43. Since the piston 417 is conical, it is easy to block the round hole inside the support foot 419. When the pressure plate 44 descends, it drives the piston 417 to descend, which prevents the piston 417 from blocking the round hole of the support foot 419, allowing gas to enter the round hole of the support foot 419. To achieve the goal of moving the pressure plate 44 as described above, and then resetting it after movement, the following solution is provided: Figures 2 to 6 As shown, a cylinder 47 is fixedly installed on the top of the positioning plate 42. The cylinder 47 is connected to the round hole inside the support foot 419 through a pipe. A negative pressure fan 48 is installed on the top of the cylinder 47 by screws. A filter structure 49 is installed on the top of the negative pressure fan 48 by screws. The filter structure 49 is composed of a fixed frame and a filter screen. A flow guide hood 410 is installed on the top of the filter structure 49 by screws. Three flow guide pipes 411 are embedded in the top of the flow guide hood 410. The air inlet end of the flow guide pipe 411 is located inside the flow guide hood 410. The three flow guide pipes 411 are connected by the same air outlet plate 412.

[0021] During use, the negative pressure fan 48 adsorbs gas during operation. At this time, the gas enters the cylinder 47 through the perforated plate 45, pressure plate 44, sleeve 43 and support foot 419, and then enters the negative pressure fan 48 through the cylinder 47 and then enters the flow hood 410 through the negative pressure fan 48. At this time, the dirt on the surface of the preform can be adsorbed simultaneously. Finally, it enters the air outlet plate 412 through the flow pipe 411, and then blows along the air outlet plate 412 to the surface of the transparent plate 46. At this time, the area above the transparent plate 46 is cleaned (when the pressure plate 44 descends). During this process, the negative pressure adsorption force continuously acts on the preform, forming a double stability with mechanical pressing. At the same time, the cleaning effect of the airflow avoids dirt from interfering with the detection, realizing the integration of "stability + cleaning". When the pressure plate 44 is reset, the gas blown out by the air outlet plate 412 flows through the gap between the pressure plate 44 and the conveyor belt 2 at the bottom of the pressure plate 44, thereby cleaning the bottom of the pressure plate 44 and ensuring the cleanliness of the bottom of the pressure plate 44. Furthermore, in order to prevent the negative pressure fan 48 from being unable to guide the outside gas when cleaning the bottom of the pressure plate 44, thus causing the device to malfunction, rectangular holes are symmetrically opened on the outer side of the cylinder 47, and baffles 418 are symmetrically embedded in the top of the pressure plate 44. The inner wall of the baffle 418 and the outer side of the cylinder 47 fit together. A guide hole is opened on one end face of the baffle 418, and the position corresponds to the rectangular hole. When the pressure plate 44 rises, the guide hole of the baffle 418 and the rectangular hole of the cylinder 47 coincide. This causes the gas adsorbed by the negative pressure fan 48 to enter the cylinder 47 along the guide hole and the rectangular hole when the negative pressure fan 48 is running. Meanwhile, the support foot 419 is blocked by the piston 417. At this time, the dual stabilization state is released, and the air path switches to the cleaning mode to avoid the negative pressure residue affecting the reset of the pressure plate 44. At the same time, it ensures that the cleaning function does not interfere with the normal switching of the stabilization function. Furthermore, in order to increase the intensity of the exhaust, an exhaust hole is provided inside the exhaust plate 412. The exhaust hole is conical in shape, and the end of the exhaust hole inside the exhaust plate 412 that is closer to the transparent plate 46 is smaller than the other end. The diameter of the outlet end is smaller than that of the other end, which causes the flowing gas to be pressurized. The pressurized gas cleans the top and bottom of the pressure plate 44 and the transparent plate 46.

[0022] Working principle: The preform enters the conveyor belt 2 through the front feeding mechanism and is embedded between the two conveyor belts 2. It flows continuously in the horizontal direction with the conveyor belt 2. When the preform reaches the entrance of the detection area, the electromagnetic adsorption structure 413 of the magnetic drive structure is energized. The electromagnetic adsorption structure 413 (electromagnet) generates a magnetic field, which forms an opposite polarity adsorption force with the magnetic adsorption structure 415 (permanent magnet) below. This force overcomes the preload force of the reset spring 414 (reset spring 414 is stretched) and drives the magnetic adsorption structure 415 to drive the pressure plate 44 downward. The pressure plate 44 moves vertically along the support foot 419 at the bottom of the positioning plate 42 via the top sleeve 43 until the lower perforated plate 45 (flexible silicone foam board) is in complete contact with the preform opening. At this time, the electromagnetic adsorption structure 413 maintains the current and locks the position of the pressure plate 44, eliminating the gap and relative movement between the preform and the conveyor belt 2 through mechanical pressing. Next, once the pressure is in place, the control system synchronously starts the negative pressure fan 48, forming a negative pressure loop in the air path. The external gas passes sequentially through the porous structure of the perforated plate 45 (gradient porosity ensures uniform adsorption), the internal cavity of the pressure plate 44, the connecting hole of the pressure plate 44, the internal round hole of the support foot 419, the pipe, the cylinder 47, and the negative pressure fan 48. The negative pressure adsorption force is transmitted to the surface of the preform through the perforated plate 45, increasing the positive pressure between the preform and the conveyor belt 2, thereby increasing the static friction force to resist the shaking and impact of the conveyor belt 2. At this time, the piston 417 moves down with the pressure plate 44 without blocking the round hole of the support leg 419, ensuring smooth airflow. At the same time, the gas is filtered along the filter structure 49 to avoid gas path blockage or preform contamination. At this time, the shooting component 3 is running, and the four cameras are exposed according to the preset time sequence. The horizontal cameras on both sides shoot the side wall of the preform, the vertical camera at the top shoots the top of the preform through the transparent plate 46, and the tilting camera at the feed end shoots the bottom of the preform. At this time, the conveyor belt 2 still drives the preform to move. After imaging is completed, the electromagnetic adsorption structure 413 is de-energized, the magnetic field disappears, the reset spring 414 is released and retracted, which drives the magnetic adsorption structure 415 and the pressure plate 44 to move upward along the support foot 419 to reset. During the upward movement of the pressure plate 44, the piston 417 rises with the support column 416, and the conical structure gradually blocks the round hole of the support foot 419. At the same time, the guide hole of the baffle 418 at the top of the pressure plate 44 coincides with the rectangular hole on the outside of the cylinder 47. External gas enters the cylinder 47 through the guide hole, avoiding negative pressure residue that could cause the pressure plate 44 to reset and get stuck.

[0023] At this time, the negative pressure fan 48 continues to run, and the air path is switched to "cleaning mode". The gas is discharged through the rectangular hole of the cylinder 47, the guide hole of the baffle 418, the negative pressure fan 48, the diversion hood 410, the diversion pipe 411 and the air outlet plate 412. The conical exhaust hole of the air outlet plate 412 is pressurized, and after pressurization, air is blown onto the surface of the transparent plate 46 and the bottom of the pressure plate 44 to clean the residual dust. At this time, the dual stabilization process ends and the cleaning process is completed simultaneously. The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. An automatic optical inspection machine for preform inspection, characterized in that, include: The frame (1) serves as the outer shell of the automatic optical inspection machine; The conveyor belt (2) is fixedly installed inside the frame (1) to transport the preforms; A shooting component (3) is mounted on the frame (1) and distributed around the conveyor belt (2) for shooting preforms on the conveyor belt (2); The press-fit stabilizing structure includes a mounting bracket (41), a positioning plate (42), a pressure plate (44), an open plate (45), a transparent plate (46), a negative pressure adsorption structure, and a magnetic drive structure; Mounting bracket (41) is fixedly installed above the conveyor belt (2); The positioning plate (42) is fixedly installed on one end face of the mounting bracket (41); A magnetic drive structure is disposed between the positioning plate (42) and the pressure plate (44) for driving the pressure plate (44) to move closer to or away from the conveyor belt (2) relative to the mounting frame (41). The pressure plate (44) is fixedly connected to the magnetic drive structure; The perforated plate (45) is fixedly connected below the pressure plate (44) and located above the conveyor belt (2) for contacting the preform; A transparent plate (46) is disposed on one end face of the pressure plate (44) near the shooting component (3) and located below the shooting component (3); The negative pressure adsorption structure is disposed inside the positioning plate (42) and the mounting bracket (41) and is connected to the perforated plate (45) to drive the gas to flow along the outside of the preform and to adsorb the preform by negative pressure.

2. The automatic optical inspection machine for preform inspection according to claim 1, characterized in that, The positioning plate (42) has four corners at the bottom integrally formed with support feet (419). A sleeve (43) is sleeved on the outside of the support feet (419). The sleeve (43) is fixedly installed above the pressure plate (44). A sealing ring is snapped on the outside of the support feet (419).

3. An automatic optical inspection machine for preform inspection according to claim 2, characterized in that, The magnetic drive structure includes an electromagnetic adsorption structure (413), which is snapped into the inside of the support foot (419). A reset spring (414) is fixedly connected to the bottom of the electromagnetic adsorption structure (413). A magnetic adsorption structure (415) is fixedly installed at the bottom of the reset spring (414). The end of the magnetic adsorption structure (415) away from the reset spring (414) is fixedly installed inside the pressure plate (44). Multiple support columns (416) are embedded in the top of the pressure plate (44) at the middle position of the magnetic adsorption structure (415). The tops of the multiple support columns (416) are snapped together with the same piston (417).

4. An automatic optical inspection machine for preform inspection according to claim 3, characterized in that, The pressure plate (44) has a cavity inside, an air inlet is provided at the top of the pressure plate (44), a round hole is provided inside the support foot (419), a connecting hole is provided at the bottom of the round hole corresponding to the top of the pressure plate (44), the piston (417) is conical in shape, and the maximum diameter of the piston (417) is greater than the outer diameter of the round hole.

5. An automatic optical inspection machine for preform inspection according to claim 4, characterized in that, A cylinder (47) is fixedly installed on the top of the positioning plate (42). The cylinder (47) is connected to the round hole inside the support foot (419) through a pipe. A negative pressure fan (48) is installed on the top of the cylinder (47) by screws. A filter structure (49) is installed on the top of the negative pressure fan (48) by screws. A flow hood (410) is installed on the top of the filter structure (49) by screws. Three flow pipes (411) are embedded on the top of the flow hood (410). The air inlet end of the flow pipe (411) is located inside the flow hood (410). The three flow pipes (411) are connected by the same air outlet plate (412).

6. An automatic optical inspection machine for preform inspection according to claim 5, characterized in that, The outer side of the cylinder (47) is symmetrically provided with rectangular holes, and the top of the pressure plate (44) is symmetrically embedded with baffles (418). The inner wall of the baffles (418) and the outer side of the cylinder (47) are in close contact with each other, and a guide hole is provided on one end face of the baffles (418).

7. An automatic optical inspection machine for preform inspection according to claim 4, characterized in that, The perforated plate (45) is specifically an open-cell silicone foam board, and the transparent plate (46) is specifically an acrylic plate.

8. An automatic optical inspection machine for preform inspection according to claim 5, characterized in that, The vent plate (412) has an exhaust hole inside, and the exhaust hole is conical in shape. The end of the exhaust hole inside the vent plate (412) that is closer to the transparent plate (46) is smaller than the other end.

9. An automatic optical inspection machine for preform inspection according to claim 3, characterized in that, The electromagnetic adsorption structure (413) specifically belongs to an electromagnet, and the magnetic adsorption structure (415) specifically belongs to a permanent magnet.

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