Visual inspection system for soft magnetic core

Abstract

The invention discloses a visual detection system for a soft magnetic core, and mainly relates to the field of visual detection. The method comprises the following detection steps: heating a magnetic core to be detected, synchronously increasing the temperature inside and outside the magnetic core by 50-160 DEG C, carrying out visible light image data acquisition and thermal imaging temperature image data acquisition on the magnetic core to be detected, and cooling the surface of the magnetic core to be detected based on air cooling before the thermal imaging temperature image data acquisition; the surface defects of the magnetic core are identified based on visible light image data, and the defects of cracks, depths of the cracks, internal pores and uneven materials are identified based on thermal imaging temperature image data. The method has the beneficial effects that not only can surface defects be identified, but also internal defects can be identified, so that efficient and accurate detection is realized.

Description

Technical Field

[0001] The invention relates to the technical field of visual inspection, in particular to a soft magnetic core visual inspection system. Background Art

[0002] Soft ferrite cores need to be inspected for defects during production. The quality of the core affects the core's magnetic permeability, high-frequency magnetic loss and other properties. Therefore, in order to ensure the overall quality of electronic components, core quality inspection is an indispensable part.

[0003] The more critical quality issues of the magnetic core usually include cracks, bubbles, and uneven density. The formation is related to the processing technology. Bubbles and cracks mainly occur during sintering or heat treatment. If the sintering atmosphere is not properly controlled (such as too high oxygen content or insufficient reducing atmosphere), the gas inside the material may not be discharged, forming bubbles. During high-temperature heat treatment, if the heating rate is too fast or the insulation time is insufficient, the gas inside the material may expand to form bubbles. If the heating or cooling rate is too fast during the sintering process, the thermal stress inside the material will increase, resulting in cracks. In addition, cracks may also be introduced on the surface of the magnetic core during machining stages such as cutting. Uneven density mainly occurs during the sintering stage. If the powder is not pressed evenly or the sintering temperature is not uniform, it may lead to uneven density distribution inside the magnetic core.

[0004] The above defects can be reflected on the surface. Usually, high-resolution CCD industrial cameras can be used to collect images of the surface of the magnetic core, and surface defects can be identified through image processing algorithms (such as grayscale processing, filtering, binarization, etc.). This visual inspection method has been followed up with the development of technologies such as convolutional neural networks, and the ability to identify surface defects has become higher and higher. However, due to the limitations of the image itself, image acquisition based on industrial cameras can only identify surface defects, that is, bubbles and cracks on the surface. The depth and impact of the cracks cannot be obtained, and defects that are not reflected on the surface cannot be obtained either. Other non-destructive testing methods can only be relied on, resulting in complex inspection links, time-consuming and labor-intensive, and the various inspections cannot be verified and coordinated with each other, resulting in a high rate of missed inspections. Summary of the invention

[0005] The object of the present invention is to provide a soft magnetic core visual inspection system, which can not only identify surface defects but also internal defects, thereby achieving efficient and accurate inspection.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A soft magnetic core visual inspection system performs the following inspection steps:

[0008] Heat the magnetic core to be tested, so that the temperature inside and outside the magnetic core rises synchronously by 50℃-160℃.

[0009] The visible light imaging data and thermal imaging temperature imaging data are collected on the magnetic core to be tested, and the surface of the magnetic core to be tested is cooled by air cooling before the thermal imaging temperature imaging data is collected;

[0010] The surface defects of the magnetic core are identified based on visible light imaging data, and the cracks and their depth, internal pores and material unevenness defects are identified based on thermal imaging temperature imaging data.

[0011] Including heating module and detection module,

[0012] The heating module is configured to heat the magnetic core to be tested, and includes a coil and a grabbing mechanism. The grabbing mechanism grabs the magnetic core and penetrates the coil, so that the temperature inside and outside the magnetic core is synchronously raised by 50°C-160°C;

[0013] The detection module includes a cold air cylinder and a turntable with an intermittent rotation stroke. The turntable is evenly provided with trays for supporting magnetic cores along its circumference. The turntable is sequentially provided with a loading position, a visible light imaging position, and a thermal imaging position along its rotation direction. The magnetic core is placed on the tray at the loading position. A CCD industrial camera is provided at the visible light imaging position, and an infrared thermal imager is provided at the thermal imaging position. The detection module also includes a cold air cylinder. An air outlet is provided on the cold air cylinder. The air outlet blows cold air to the magnetic core before it reaches the thermal imaging position.

[0014] The heating module also includes a column base, an arm is provided on the top of the column base, the arm has a swing stroke, the swing stroke has a material taking stroke position and a material discharging stroke position, a lifting arm with a lifting stroke is provided at the outer end of the arm, and the grabbing mechanism is arranged at the bottom end of the lifting arm.

[0015] When the arm is in the discharge stroke position, the magnetic core grasped by the grasping mechanism corresponds coaxially to the coil;

[0016] When the lifting arm is at the top of its lifting stroke, the grabbing mechanism is located above the coil.

[0017] When the lifting arm is at the bottom of its lifting stroke, the grabbing mechanism is located below the coil.

[0018] The tray located on the upper material level of the turntable is coaxially located below the coil.

[0019] The lifting arm includes an upright tubular member, the top end of the tubular member is provided with a top frame fixed relative to it, the circumferential side of the tubular member is provided with at least two vertically extending optical rods, the outer end of the arm is provided with a sliding sleeve that slides up and down with the optical rod, the arm is provided with a mounting seat near the column base, an oil cylinder is fixedly installed below the mounting seat, the top end of the oil cylinder is telescopically matched with a cylinder rod, the top end of the cylinder rod is fixed with a connecting frame, and the top frame is fixed to the connecting frame.

[0020] The lifting arm includes an upright tubular member, the top of the tubular member is coaxially rotatably connected to a central axis driven by a motor, a central gear is fixed to the bottom end of the central axis, and a side gear is provided on the circumference of the central gear and is rotatably mounted on the top of the tubular member, the side gear and the central gear are meshed, the grabbing mechanism includes a shaft and an angle plate at its bottom end, the shaft is at least two and extends upright, the shaft is located in the tubular member and is rotatably connected relative to the tubular member, the top of the shaft is coaxially fixed to the side gear, one end of the angle plate is fixed to the bottom end of the shaft, the top surface of the other end of the angle plate is provided with a slope, and an upwardly protruding limit column is fixed to the middle of the angle plate, the limit column is used to contact the annular inner wall of the annular magnetic core.

[0021] The turntable is provided with a plurality of rotating seats distributed in a ring near the edge thereof, a rotating cylinder is coaxially penetrated through the rotating seat and rotatably connected thereto, a bottom wheel coaxial therewith is fixed to the bottom end of the rotating cylinder, the bottom wheel is located below the turntable, the tray is coaxially fixed to the top end of the rotating cylinder, the distance from the top surface of the tray to the bottom end of the coil is greater than the height of the magnetic core, and a through hole penetrating the rotating cylinder is provided in the center of the tray.

[0022] A mounting frame is provided below the turntable, and the turntable is rotatably mounted on the mounting frame and can realize intermittent rotation based on motor drive. Two vertical shafts driven by a motor can also be rotatably mounted on the mounting frame, and a friction wheel located below the turntable is fixed on the top of the vertical shaft. The two friction wheels are respectively in contact with the bottom wheels located at the visible light imaging position and the thermal imaging position. When the turntable is in an intermittent stop state, the friction wheel pushes the rotating cylinder to rotate at least one circle.

[0023] The cold air tube is centrally located in the middle of the turntable and is cylindrical. The exterior of the cold air tube is a single color. The air outlets of the cold air tube are arranged corresponding to the visible light imaging position, and the overall range of the air outlets does not exceed the horizontal projection range of the magnetic core located on the visible light imaging position tray.

[0024] A material unloading position is also provided between the material loading position and the thermal imaging position of the turntable, and the turntable is provided with a material unloading paddle and a material dropping chute at the material unloading position, the bottom side of the material unloading paddle is higher than the top surface of the tray and lower than the top surface of the magnetic core, the inner end of the material unloading paddle is close to the inner side of the tray, the outer end of the material unloading paddle protrudes out of the edge of the turntable and is inclined in the rotation direction of the turntable, the top side of the material dropping chute is located below the tray, the inner end of the material unloading chute is arranged close to the rotating drum, and a vertical plate is provided on the side of the material unloading chute away from the material unloading paddle, the bottom of the material unloading chute is an inclined slope, and the side close to the vertical plate is the lowest side.

[0025] A reject position is also provided between the thermal imaging position and the unloading position of the turntable, and the turntable is provided with a reject paddle and a reject chute at the reject position, the inner end of the reject paddle is close to the inner side of the tray, the outer end of the reject paddle protrudes from the edge of the turntable and is inclined in the rotation direction of the turntable, the outer end of the reject paddle is fixed on the lifting rod, when the lifting rod is raised, the bottom side of the reject paddle is higher than the top surface of the magnetic core, when the lifting rod falls, the bottom side of the reject paddle is close to the top surface of the tray, the top side of the reject chute is located below the tray, the inner end of the reject chute is arranged close to the rotating drum, and a vertical plate is provided on the side of the reject chute away from the unloading paddle, the bottom of the reject chute is an inclined slope and the side close to the vertical plate is the lowest side.

[0026] It also includes a material preparation module, which has a material preparation trough, one end of which is provided with a chute connected thereto, the chute is a straight trough and the end away from the material preparation trough is provided with a flat trough, the trough width of the chute and the trough width of the flat trough are both adapted to the outer diameter of the magnetic core, the trough bottom of the chute and the trough bottom of the material preparation trough are coplanar and are both inclined toward one end of the flat trough, an arc-shaped baffle is provided at the end of the flat trough away from the chute, the arc-shaped baffle is semicircular, the inner diameter of the arc-shaped baffle corresponds to the outer diameter of the magnetic core, the bottom of the flat trough is provided with a strip opening, the width of the strip opening is greater than the inner diameter of the magnetic core.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] By heating the magnetic core, the internal and external temperatures of the magnetic core are kept consistent at a higher temperature, and by cooling the surface based on air cooling, the surface is cooled quickly. Due to the difference between the defects of cracks, pores, and uneven materials and the heat conduction of the surrounding materials, an obvious temperature gradient is presented during the temperature loss process, which can be presented in the temperature image data, thus providing a basis for identifying internal defects and crack depths. The temperature image data can also be integrated with the visible light image data to further accurately detect the conclusion and achieve data coordination. After the detection based on our system, other subsequent non-destructive detection methods for the corresponding defects can be omitted, thereby greatly reducing the detection links, improving production efficiency, and streamlining costs and configurations. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is an overall schematic diagram of the present invention.

[0030] Figure 2 It is a top view of the present invention.

[0031] Figure 3 yes Figure 2 A partial schematic diagram of the loading tray and the mechanism above it under the AA section.

[0032] Figure 4 It is a schematic diagram of component disassembly of the grabbing mechanism of the present invention.

[0033] Figure 5 It is a schematic diagram of the inner wall structure of the grabbing mechanism and the lifting arm of the present invention.

[0034] Figure 6 It is a schematic diagram of the detection module of the present invention.

[0035] Figure 7 It is a bottom schematic diagram of the detection module of the present invention.

[0036] Figure 8 yes Figure 2 Schematic diagram of the structure under CC section.

[0037] Fig. 9 It is a schematic diagram of embodiment 2 of the present invention.

[0038] Fig.10 It is a schematic diagram of the material preparation module of the present invention.

[0039] Fig.11 It is a schematic diagram of the cooperation between the grabbing mechanism of the present invention and the magnetic core from the bottom surface perspective.

[0040] Numbers shown in the accompanying drawings:

[0041] 1. Material preparation trough; 2. Chute; 3. Flat trough; 4. Arc baffle; 5. Strip mouth; 6. Column base; 7. Arm; 8. Coil; 9. Tube; 10. Top frame; 11. Lower support; 12. Bare rod; 13. Sliding sleeve; 14. Cylinder; 15. Connecting frame; 16. Side gear; 17. Central gear; 18. Angle plate; 19. Limiting column; 20. Slope; 21. Axle; 22. Turntable; 23. Rotating seat; 24. Rotating cylinder; 25. Bottom wheel; 26. Tray; 27. Through hole; 28. CCD industrial camera; 29. ​​Infrared thermal imager; 30. Cold air cylinder; 31. Air outlet; 32. Mounting frame; 33. Rotating shaft; 34. Vertical shaft; 35. Friction wheel; 36. Unloading paddle; 37. Support rod; 38. Unloading chute; 39. Vertical plate; 40. Rejection paddle; 41. Lifting rod; 42. Lifting cylinder seat; 43. Rejection chute. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0043] Embodiment 1:

[0044] This soft magnetic core visual inspection system is mainly used to reconstruct the visual inspection process of magnetic cores and achieve a breakthrough in the limitation of visual inspection to surface defects. This design mainly detects annular magnetic cores. From the perspective of system configuration, it mainly includes the following links:

[0045] Material preparation module, temperature rise module and detection module.

[0046] Material preparation module

[0047] It is mainly used to provide material loading preparation for this system and realize the automatic coordination of material loading in the previous link. The structure includes a material preparation trough 1, which adopts a receiving trough structure with an open top, which can be conveniently coordinated with other automated equipment or manual loading. During specific production, materials can be poured into the material preparation trough 1 manually, or a conveyor belt can be used to achieve automatic conveying in series with the upstream process. A silo can also be set above the material preparation trough 1, and a material discharge channel close to the notch of the material preparation trough 1 is provided at the bottom of the silo, so that the workpieces in the material preparation trough 1 can be replenished by controlling the discharge.

[0048] One end of the material preparation trough 1 is provided with a chute 2 connected thereto, the chute 2 is a straight trough and an end thereof away from the material preparation trough 1 is provided with a flat trough 3.

[0049] The bottom of the material preparation trough 1 is provided with an inclined bottom plate, and the side of the bottom plate close to the chute 2 is inclined downward, so that the magnetic core products automatically gather from the higher side of the bottom plate to the lower side, and then automatically enter the chute 2.

[0050] One end of the material preparation chute 1 connected to the chute 2 is provided with a V-shaped bell-mouth structure to guide the workpiece to the chute 2.

[0051] The bottom of the material preparation trough 1 and the top surface of the bottom of the chute 2 are coplanar, that is, the bottom of the chute 2 is also an inclined structure in the same direction, and the magnetic core workpiece automatically moves to the bottom end of the chute 2 based on gravity.

[0052] The width of the chute 2 is adapted to the outer diameter of an annular magnetic core and can accommodate a magnetic core to pass through, so that the magnetic cores are arranged in a row on the chute 2 and pushed toward the flat chute 3 in an orderly manner.

[0053] The width of the flat groove 3 corresponds to that of the chute 2. An arc-shaped baffle 4 is provided at one end of the flat groove 3 away from the chute 2. The arc-shaped baffle 4 is semicircular, and the inner diameter of the arc-shaped baffle 4 corresponds to the groove width (the outer diameter of the magnetic core), so that the frontmost magnetic core is positioned by the arc-shaped baffle 4. The bottom of the flat groove 3 is horizontal. The magnetic core on the flat groove 3 is squeezed and pushed forward by the inclination of the chute 2 and the magnetic cores arranged on the chute 2, so that the frontmost magnetic core can be close to the inner wall of the arc-shaped baffle 4, providing positioning for grabbing. The bottom of the flat groove 3 is provided with a strip-shaped opening 5, which runs through the bottom of the flat groove 3. The width of the strip-shaped opening 5 is greater than the inner diameter of the magnetic core, which can support the bottom surface of the magnetic core and facilitate grabbing.

[0054] Heating module

[0055] It includes a column base 6, which is used for fixed installation and supports the entire module. The column base 6 extends upright and an arm 7 is installed on the top of the column base 6. One end of the arm 7 is rotatably installed on the top of the column base 6. The rotation of the arm 7 is based on motor drive, and the specific structure is not limited to any rotation drive structure and control system.

[0056] The arm 7 has a swing stroke, and the swing stroke has a material taking stroke position and a material discharging stroke position, and the arm 7 reciprocates between the two stroke positions based on its swing stroke. The material taking stroke position corresponds to the front end of the flat slot 3, and a coil 8 is provided at the material discharging stroke position.

[0057] The end of the arm rod 7 is provided with a lifting arm with a lifting stroke relative to the arm rod 7, and the bottom end of the lifting arm is provided with a grabbing mechanism for grabbing the magnetic core.

[0058] The lifting arm includes an upright tubular member 9, which is a straight columnar tube with a circular tube cavity in the middle. The top of the tubular member 9 is provided with a top frame 10 fixed relative to it, and the tubular member 9 is provided with a lower support 11 near the bottom end. An upright extending optical rod 12 is fixedly installed between the top of the top frame 10 and the lower support 11. There are three optical rods 12 and they are evenly distributed circumferentially relative to the tubular member 9. The circumferential side of the tubular member 9 is provided with a V-shaped make way groove corresponding to the optical rod 12, so as to make the entire lifting support structure more compact and not protrude the outer diameter of the workpiece. The outer end of the arm 7 is provided with a mounting hole for the lifting arm to pass through, the mounting hole is circular and has three sliding sleeves 13 fixed on the circumference, the light rod 12 passes through the sliding sleeve 13 and slides up and down with the sliding sleeve 13 to realize the lifting stroke guide of the lifting arm, the arm 7 is provided with a mounting seat near the column base 6, and an oil cylinder 14 is fixedly installed below the mounting seat, and the top end of the oil cylinder 14 is telescopically matched with a cylinder rod, and the top end of the cylinder rod is fixed with a connecting frame 15, and the top end of the top frame 10 is also fixed on the connecting frame 15, so that the lifting control of the lifting arm is based on the oil rod drive and positioning.

[0059] The top of the tubular member 9 is coaxially and centrally connected to a central shaft, and the bottom end of the central shaft is provided with a central gear 17 located inside the tubular member 9. The peripheral side of the central gear 17 is provided with a side gear 16 rotatably mounted on the top of the tubular member 9, and the side gear 16 is meshed with the central gear 17.

[0060] The gripping mechanism comprises a shaft rod 21 and an angle plate 18 .

[0061] The shaft rods 21 are three vertically arranged and located in a circumferential array in the lumen. The shaft rods 21 are staggered and rationally arranged with the give way grooves. The top and bottom ends of the shaft rods 21 are rotatably mounted on the tubular member 9 respectively. The top end of the shaft rod 21 is coaxially fixed with the side gear 16. Based on the rotation of the central gear 17, the three shaft rods 21 can be driven to rotate at the same time.

[0062] The space between the bottom of the top frame 10 and the top of the tubular member 9 is used to install the first stepper motor, and the bottom end of the first stepper motor is provided with a first motor shaft connected to the central shaft, so as to realize the driving control of the central gear 17 and enable the arm 7 to complete its swing stroke.

[0063] The bottom end of the tubular member 9 is penetrated by the bottom end of the shaft 21, and a corner plate 18 located below the tubular member 9 is fixed to the bottom end of the shaft 21. One end of the corner plate 18 is fixed to the bottom end of the shaft 21, and the top surface of the other end of the corner plate 18 is provided with a slope 20, which is beneficial to the contact and guidance with the bottom surface of the magnetic core when swinging outward. A limiting column 19 protruding upward is fixed to the middle part of the corner plate 18, and the limiting column 19 is a cylindrical member that contacts smoothly with the inner wall of the magnetic core. When the shaft 21 rotates, the angle plate 18 is fixed eccentrically relative to the shaft 21, and swings outward to expand, or swings inward to retract (retracted within the projection range of the tubular member 9, so that it can easily penetrate the inner ring of the magnetic core) as the shaft 21 rotates. When expanding outward, the limit column 19 can protrude beyond the projection range of the tubular member 9 and abut against the inner wall of the inner ring of the magnetic core, thereby completing axial positioning, and the slope 20 is supported on the bottom annular end face of the magnetic core as it swings outward to lift the magnetic core. The two cooperate to achieve high-precision grasping of the magnetic core.

[0064] Based on the above structure, the device has the following limitations in terms of spatial position and travel coordination:

[0065] When the arm 7 is located at the material taking stroke position, the central axis and the tubular member 9 are coaxial with the arc baffle 4 (of the flat groove 3 at the front end of the material preparation module), and thus coaxial with the magnetic core located at the front end of the flat groove 3; and when the lifting arm falls, the angle plate 18 can pass through the strip opening 5 and be located below the strip opening 5, and the magnetic core located at the front end of the flat groove 3 can be grabbed upward by swinging the angle plate 18 outward;

[0066] When the arm 7 is located in the discharge stroke position, the central axis and the tubular member 9 are coaxial with the coil 8, and when the lifting arm is located at the upper end of its stroke, the bottom end of the lifting arm is located above the coil 8, and when the lifting arm is located at the lower end of its stroke, the magnetic core clamped by the bottom end of the lifting arm is completely located below the coil 8, thereby achieving penetration of the coil 8.

[0067] By combining the lifting stroke and the swing stroke, the magnetic core is lifted from the arc baffle 4 of the flat groove 3, and the lower part of the magnetic core is heated through the coil 8 by rotating.

[0068] Based on the heating condition of the coil 8 , the tubular member 9 , the shaft rod 21 , the light rod member 12 , the angle plate 18 , etc. are made of ceramics and are not affected by the coil 8 .

[0069] Based on the coil 8 using electric current to generate an alternating magnetic field, when the magnetic core passes through the coil 8, it is converted into heat energy to achieve heating. This heating method can quickly heat up, and the internal and external temperatures remain uniform, providing a basis for the temperature difference in the next step of cooling. The coil 8 is spirally wound, and the inner diameter of the coil 8 is larger than the outer diameter of the magnetic core. Based on the positioning of the lifting arm in the swing stroke, and the axial positioning of the magnetic core by the limit column 19 when the magnetic core is grabbed, the magnetic core can pass through the coil 8 in the center (for clear display in the figure, the gap between the magnetic core and the coil 8 is large, and the gap can be reduced in actual application).

[0070] Detection module

[0071] A turntable 22 with an intermittent rotation stroke is included, and the turntable 22 is arranged at a height below the coil 8 .

[0072] The turntable 22 has 8 installation positions distributed in a ring near the edge. Since the turntable 22 rotates intermittently, the turntable 22 pauses for several seconds (may be 10s-30s) every time it rotates 1 / 8 of a circle, and then repeats this process.

[0073] A rotating seat 23 is fixed on the installation position, and a rotating cylinder 24 is coaxially penetrated and rotatably connected in the rotating seat 23. A bottom wheel 25 coaxial with the rotating cylinder 24 is fixed at the bottom end of the rotating cylinder 24, and the bottom wheel 25 is located below the turntable 22. A tray 26 integrally formed with the rotating cylinder 24 is provided at the top of the rotating cylinder 24, and the distance from the top surface of the tray 26 to the bottom end of the coil 8 is greater than the height of the magnetic core. A through hole 27 penetrating the rotating cylinder 24 is provided in the center of the tray 26, and the through hole 27 provides a space for the angle plate 18 at the bottom end of the lifting arm, so as to facilitate the placement of the magnetic core on the tray 26.

[0074] Specifically, the mounting position is a circular groove with screw holes, and a circular hole is provided in the center of the circular groove for making room for the component. A flange is provided at the bottom of the rotating seat 23, which is fixed in the circular groove by screws. The rotating seat 23 is a cylindrical structure, and the inner cylinder part provides a rotating mounting support for the rotating cylinder 24.

[0075] The wheelbase from the coil 8 to the center of the turntable 22 corresponds to the wheelbase from the rotating cylinder 24 to the center of the turntable 22 , so that the coil 8 can be coaxial with any rotating cylinder 24 based on the rotation of the turntable 22 .

[0076] A loading position, 1 to 3 visible light imaging positions, 1 to 3 thermal imaging positions, and a unloading position are arranged on the side of the turntable 22 .

[0077] The loading position is used to place the magnetic core on the tray 26. The coil 8 is coaxially corresponding to the rotating cylinder 24 located at the loading position. When the lifting arm falls, the heated magnetic core can be placed in the center on the tray 26 located at the loading position.

[0078] The loading position, visible light imaging position, thermal imaging position, and unloading position are sequentially arranged along the rotation stroke of the turntable 22 .

[0079] In this example, only one visible light imaging position and one thermal imaging position are set, and a CCD industrial camera 28CCD and an infrared thermal imager 29 are also installed on the surrounding side of the turntable 22. The CCD industrial camera 28CCD is set corresponding to the visible light imaging position, and the shooting direction corresponds to the tray 26 of the visible light imaging position. The infrared thermal imager 29 is set corresponding to the thermal imaging position, and the shooting direction corresponds to the tray 26 of the thermal imaging position.

[0080] The infrared thermal imager 29 may be a highly sensitive infrared thermal imager 29, such as the MLX90640 infrared array sensor of Melexis, which has high resolution (32×24 pixels) and a wide temperature detection range (-40° C. to 300° C.), and is suitable for temperature distribution detection of the magnetic core.

[0081] A cold air cylinder 30 is provided in the center of the turntable 22. A cold air source is connected to the top of the cold air cylinder 30. The cold air cylinder 30 is a straight cylindrical cavity structure with a circular cross-section. The outer surface of the cold air cylinder 30 is coated with white paint, thereby providing a pure background color for visible light shooting and facilitating the removal of impurities in the later image processing. The cold air cylinder 30 is provided with an air outlet 31 corresponding to the visible light imaging position. The air outlet 31 can adopt a grid structure or a mesh structure. The overall range of the air outlet 31 does not exceed the horizontal projection range of the magnetic core located on the tray 26, so it will not be displayed in the collected visible light image.

[0082] At the same time, the cold air cylinder 30 can also provide a balanced background with a temperature significantly lower than that of the magnetic core for the thermal imaging image, thereby avoiding interference with the thermal imaging of the magnetic core and obtaining "clean" thermal imaging image data.

[0083] A rotating shaft 33 is fixed in the center of the turntable 22, and a mounting frame 32 is provided below the turntable 22. The lower part of the rotating shaft 33 is rotatably mounted on the mounting frame 32 through a bearing. The mounting frame 32 is made of plate cutting and bending to provide a mounting position for the components. In actual equipment, a casing is also provided below the turntable 22, and the mounting frame 32 is fixed in the casing by bolts, thereby supporting and fixing the equipment. However, in order to express the internal structure, the casing is deleted in the figure to facilitate observation of the internal components.

[0084] The mounting frame 32 is fixed with a second stepper motor and a third stepper motor. The second stepper motor is connected to the rotating shaft 33 via a reducer to drive the rotating shaft 33 .

[0085] Two vertical shafts 34 are rotatably mounted on the mounting frame 32. The bottom end of the vertical shaft 34 is rotatably connected to the third stepping motor through a reducer to achieve driven rotation. A friction wheel 35 located below the turntable 22 is fixed to the top end of the vertical shaft 34. The friction wheel 35 can be a rubber wheel. The two friction wheels 35 are respectively arranged close to the visible light imaging position and the thermal imaging position, and are respectively in contact with the bottom wheel 25 at the bottom end of the rotating cylinder 24 located at the visible light imaging position and the thermal imaging position, thereby driving the tray 26 to rotate. The diameter of the friction wheel 35 is (3-6) times smaller than the diameter of the bottom wheel 25, and the slow rotation of the tray 26 can be achieved by reducing the speed. When the turntable 22 rotates the magnetic core to the visible light imaging position based on its intermittent rotation stroke, the corresponding rotating cylinder 24 below it is driven to rotate by the friction wheel 35, so that the magnetic core (while the turntable 22 is stopped) rotates slowly with the tray 26 to obtain at least one cycle of visible light image data, and during the rotation, the surface can be quickly cooled evenly through the air outlet 31. When the turntable 22 rotates the magnetic core to the thermal imaging position based on its intermittent rotation stroke, the magnetic core can be rotated slowly with the tray 26 (while the turntable 22 is stopped) to obtain at least one cycle of thermal imaging temperature image data.

[0086] The unloading position of the turntable 22 is provided with an unloading paddle 36 fixedly arranged relative to its mounting frame 32, and the unloading paddle 36 is vertically arranged, and the distance between the inner end of the unloading paddle 36 and the center of the turntable 22 is smaller than the minimum distance between the tray 26 and the center of the turntable 22, and the outer end of the unloading paddle 36 is inclined in the rotation direction of the turntable 22 to more gently guide the magnetic core to fall; the bottom side of the unloading paddle 36 is higher than the top surface of the tray 26, and the top side of the unloading paddle 36 is higher than the top surface of the magnetic core, so that when the tray 26 passes by the unloading paddle 36, the magnetic core above is blocked by the unloading paddle 36 and falls. The outer end of the material discharge paddle 36 is provided with a support rod 37 located on the outside of the turntable 22, and the top of the support rod 37 is provided with a slot, and the slot is used to insert the material discharge paddle 36. The top or middle of the slot is provided with a fixing screw that cooperates with it and penetrates through it. The fixing screw can be a double-headed screw, and the clamping of the material discharge paddle 36 is achieved by means of nuts at both ends. The bottom end of the support rod 37 can be fixed to the outside of the casing for easy adjustment and fixation.

[0087] A material dropping chute 38 is also provided on one side of the material dropping paddle 36, and the top side of the material dropping chute 38 is located below the bottom surface of the tray 26, and the inner end of the material dropping chute 38 is arranged close to the circumference of the drum for receiving the magnetic cores pushed down by the material dropping paddle 36. A vertical plate 39 is provided on the side of the material dropping chute 38 away from the material dropping paddle 36, and the bottom of the material dropping chute 38 is an inclined slope and the side close to the vertical plate 39 is the lowest side. A conveying device or a accommodating device can be arranged below the material dropping chute 38 for receiving the magnetic cores that have been inspected. It is recommended to use a conveying device so that the magnetic cores are conveyed in sequence to facilitate picking up when defects are found.

[0088] Based on the above description of the system hardware, the corresponding timing action steps are:

[0089] First, load the material (ring-shaped magnetic core) into the material preparation trough 1, place the magnetic core upright in the material preparation trough 1, and arrange the magnetic core in a row in the chute 2 and the flat trough 3 based on gravity and the inclined surface, so that there is always a magnetic core workpiece at the arc baffle 4.

[0090] S1, the arm 7 rotates to the material taking stroke position, the lifting arm descends until the angle plate 18 is located below the bottom surface of the magnetic core, the angle plate 18 swings outward, so that the limit column 19 abuts against the inner circle of the magnetic core, the top surface of the angle plate 18 supports the bottom surface of the magnetic core, and the lifting arm rises to lift the magnetic core;

[0091] S2, the arm 7 rotates from the material taking stroke position to the material discharging stroke position;

[0092] S3, the lifting arm descends until the magnetic core passes through the coil 8;

[0093] S4, the lifting arm descends to the bottom of the magnetic core and falls on the tray 26 at the loading position, the angle plate 18 rotates inward and closes, and after releasing the grip on the magnetic core, the lifting arm rises to the top of its travel.

[0094] S5, the heating module repeats the actions of s1-s4, while the turntable 22 maintains its intermittent rotation stroke. When the turntable 22 stops rotating, the magnetic core is loaded at the loading position, and the CCD industrial camera 28CCD and the infrared thermal imager 29 collect image data. At the same time, the surface of the magnetic core that has passed the visible light imaging position is quickly cooled by cold air; the magnetic core on the tray 26 that has passed the unloading position is pushed off the turntable 22, leaving the tray 26 empty;

[0095] Based on the configuration and control method of the above system, we can achieve a breakthrough improvement in the visualization detection of magnetic cores. The new method adopted is:

[0096] Equipment inspection: Check all the testing instruments used to ensure the normal operation of the equipment, and conduct pre-operation tests on the coil 8, turntable 22, arm 7, lifting arm and grabbing mechanism to check that they are operating well and positioning accurately;

[0097] Start detection:

[0098] Based on the heating module, the arm 7, the lifting arm and the grabbing mechanism are used to grab the magnetic cores one by one, so that the magnetic cores pass through the coil 8, thereby achieving a temperature increase of 90-120 degrees for the magnetic cores. Since the coil 8 is used for heating, the temperature can be increased quickly and evenly, so that the internal and external temperatures are consistent;

[0099] The magnetic core passing through the coil 8 is placed on the tray 26. Based on the intermittent rotation of the turntable 22, the magnetic core is driven to rotate to the CCD position of the CCD industrial camera 28 first, and rotate at this position to complete the visible light image data collection of the magnetic core for at least one week. During the rotating shooting process, the surface of the magnetic core is cooled by cold air synchronously; then the magnetic core is rotated to the infrared thermal imager 29 position, and rotates at this position to complete the temperature image data collection of the magnetic core for at least one week;

[0100] The magnetic cores that have been tested on the turntable 22 are unloaded, leaving the tray 26 empty to prepare for the loading of continuous magnetic cores.

[0101] Data processing:

[0102] Based on the collected visible light image data, the magnetic core workpiece with surface defects is identified. The surface defects that can be identified are mainly pits and cracks that can be clearly seen on the surface, which lead to defects such as uneven surface.

[0103] Based on the collected temperature image data, the crack depth, internal pores, and material unevenness of the magnetic core workpiece are identified.

[0104] After heating, the internal and external temperatures of the magnetic core workpiece are balanced to exceed 100°C. During the process of blowing cold air to cool the surface, the cooling rate in the deep gaps and internal pores is different from that in the surrounding solidified magnetic core material. The cooling rate of the uneven parts of the material is also different, resulting in a corresponding temperature distribution presented in the image data.

[0105] Characteristics of crack detection images: Since cracks affect heat conduction, heat accumulates or dissipates at the cracks, forming an obvious temperature gradient, which appears as a temperature gradient in the shape of a gap on the image; and based on different depths, the resulting temperature gradient is different, so the depth of the crack can be detected. The deeper the crack, the more obvious the temperature difference.

[0106] Porosity detection image features: The pore area will show a different temperature change rate than the surrounding material during the cooling process. The thermal conductivity of the air inside the pore is low, resulting in a slower temperature drop in the pore area, which is manifested as high-temperature spots in the local area.

[0107] Material inhomogeneity detection image characteristics: Uneven material composition or structure will lead to different thermal conductivity characteristics, and irregular temperature distribution will appear in the thermal image.

[0108] Therefore, the following data processing is used for temperature image data:

[0109] The collected temperature distribution image is converted into pseudo color to enhance the visual effect of the image.

[0110] Analyze the temperature abnormality area in the image and compare it with the thermal image of the standard sample to identify the defect location. The thermal image of the standard sample can be a defect-free standard magnetic core, using this system, and after the same heating and cooling steps as above, obtain at least one week of temperature image data.

[0111] The collected temperature distribution image is fused and analyzed with the visible light image data, and the defect location obtained by identification is comprehensively judged. The characteristics of the two image data are combined to improve the detection accuracy and reliability.

[0112] Through this system, the improved detection method adopted can not only detect the surface defects of the magnetic core, but also reflect the depth of the cracks, and quickly identify the internal pores and uneven materials based on visual detection, thereby simplifying the detection means and greatly improving the detection accuracy. And through the combination of two types of image data, the location and type of defects can be further identified, improving the reliability of the detection conclusion.

[0113] Embodiment 2:

[0114] On the basis of Example 1, this example adds a reject position on the working position of the turntable 22 of the detection module; the reject position is located between the thermal imaging position and the unloading position, and a reject mechanism is provided on the outer side of the reject position of the turntable 22, and the reject mechanism includes a lifting cylinder seat 42, and the lifting cylinder seat 42 is located outside the turntable 22 and is fixed relative to the casing or the mounting frame 32, and the upper part of the lifting cylinder seat 42 is provided with a lifting rod 41 which is lifted up and down relative to it, and a reject paddle 40 is fixed to the top of the lifting rod 41, and the fixing method of the reject paddle 40 and the top of the lifting rod 41 can adopt the installation structure of the unloading paddle 36 and the support rod 37, when the reject paddle 40 rises to the top, the bottom side of the reject paddle 40 is higher than the top surface of the magnetic core, so that the magnetic core can pass smoothly, and when the reject paddle 40 descends, the reject paddle 40 is at the same height as the unloading paddle 36, thereby pushing the passing magnetic core off.

[0115] A rejection chute 43 is also provided on the outer side of the rejection position, and its structure and shape are the same as those of the blanking chute 38 , and is used to receive the magnetic core pushed down by the rejection paddle 40 .

[0116] The lifting and lowering of the lifting rod 41 can be driven by an electric push rod. The electric push rod can be installed in the lifting cylinder, or the electric push rod can be directly used as the lifting cylinder to complete the lifting and lowering control of the rejection paddle 40, and the lifting and lowering of the rejection paddle 40 is based on the recognition conclusion of the temperature image data and the visible light image data. When it is recognized that the passing magnetic core has defects, the rejection paddle 40 falls and pushes the defective magnetic core down. When the data is normal, the rejection paddle 40 rises, which does not affect the passing of the magnetic core and is uniformly collected at the discharge position.

Claims

1. A soft magnetic core visual inspection system, characterized in that: Perform the following detection steps: Heat the magnetic core to be tested, so that the temperature inside and outside the magnetic core rises synchronously by 50℃-160℃. The visible light imaging data and thermal imaging temperature imaging data are collected on the magnetic core to be tested, and the surface of the magnetic core to be tested is cooled by air cooling before the thermal imaging temperature imaging data is collected; The surface defects of the magnetic core are identified based on visible light imaging data, and the cracks and their depth, internal pores and material unevenness defects are identified based on thermal imaging temperature imaging data.

2. A soft magnetic core visual inspection system according to claim 1, characterized in that: Including heating module and detection module, The heating module is configured to heat the magnetic core to be tested, and includes a coil and a grabbing mechanism. The grabbing mechanism grabs the magnetic core and penetrates the coil, so that the temperature inside and outside the magnetic core is synchronously raised by 50°C-160°C; The detection module includes a cold air cylinder and a turntable with an intermittent rotation stroke. The turntable is evenly provided with trays for supporting magnetic cores along its circumference. The turntable is sequentially provided with a loading position, a visible light imaging position, and a thermal imaging position along its rotation direction. The magnetic core is placed on the tray at the loading position. A CCD industrial camera is provided at the visible light imaging position, and an infrared thermal imager is provided at the thermal imaging position. The detection module also includes a cold air cylinder. An air outlet is provided on the cold air cylinder. The air outlet blows cold air to the magnetic core before it reaches the thermal imaging position.

3. A soft magnetic core visual inspection system according to claim 2, characterized in that: The heating module also includes a column base, an arm is provided on the top of the column base, the arm has a swing stroke, the swing stroke has a material taking stroke position and a material discharging stroke position, a lifting arm with a lifting stroke is provided at the outer end of the arm, and the grabbing mechanism is arranged at the bottom end of the lifting arm. When the arm is in the discharge stroke position, the magnetic core grasped by the grasping mechanism corresponds coaxially to the coil; When the lifting arm is at the top of its lifting stroke, the grabbing mechanism is located above the coil. When the lifting arm is at the bottom of its lifting stroke, the grabbing mechanism is located below the coil. The tray located on the upper material level of the turntable is coaxially located below the coil.

4. A soft magnetic core visual inspection system according to claim 3, characterized in that: The lifting arm comprises a vertically arranged tubular member, the top of which is provided with a top frame fixed relatively thereto, the peripheral side of the tubular member is provided with at least two vertically extending light rods, the outer end of the arm is provided with a sliding sleeve that slides up and down with the light rod, the arm is provided with a mounting seat near the column base, an oil cylinder is fixedly installed below the mounting seat, the top of the oil cylinder is telescopically matched with a cylinder rod, the top of the cylinder rod is fixed with a connecting frame, and the top frame is fixed on the connecting frame; and / or The lifting arm includes an upright tubular member, the top of the tubular member is coaxially rotatably connected to a central axis driven by a motor, a central gear is fixed to the bottom end of the central axis, and a side gear is provided on the circumference of the central gear and is rotatably mounted on the top of the tubular member, the side gear and the central gear are meshed, the grabbing mechanism includes a shaft and an angle plate at its bottom end, the shaft is at least two and extends upright, the shaft is located in the tubular member and is rotatably connected relative to the tubular member, the top of the shaft is coaxially fixed to the side gear, one end of the angle plate is fixed to the bottom end of the shaft, the top surface of the other end of the angle plate is provided with a slope, and an upwardly protruding limit column is fixed to the middle of the angle plate, the limit column is used to contact the annular inner wall of the annular magnetic core.

5. A soft magnetic core visual inspection system according to claim 2, characterized in that: The turntable is provided with a plurality of rotating seats distributed in a ring near the edge thereof, a rotating cylinder is coaxially penetrated through the rotating seat and rotatably connected thereto, a bottom wheel coaxial therewith is fixed to the bottom end of the rotating cylinder, the bottom wheel is located below the turntable, the tray is coaxially fixed to the top end of the rotating cylinder, the distance from the top surface of the tray to the bottom end of the coil is greater than the height of the magnetic core, and a through hole penetrating the rotating cylinder is provided in the center of the tray.

6. A soft magnetic core visual inspection system according to claim 5, characterized in that: A mounting frame is provided below the turntable, and the turntable is rotatably mounted on the mounting frame and can realize intermittent rotation based on motor drive. Two vertical shafts driven by a motor can also be rotatably mounted on the mounting frame, and a friction wheel located below the turntable is fixed on the top of the vertical shaft. The two friction wheels are respectively in contact with the bottom wheels located at the visible light imaging position and the thermal imaging position. When the turntable is in an intermittent stop state, the friction wheel pushes the rotating cylinder to rotate at least one circle.

7. A soft magnetic core visual inspection system according to claim 6, characterized in that: The cold air tube is centrally located in the middle of the turntable and is cylindrical. The exterior of the cold air tube is a single color. The air outlets of the cold air tube are arranged corresponding to the visible light imaging position, and the overall range of the air outlets does not exceed the horizontal projection range of the magnetic core located on the visible light imaging position tray.

8. A soft magnetic core visual inspection system according to claim 2, characterized in that: A material unloading position is also provided between the material loading position and the thermal imaging position of the turntable, and the turntable is provided with a material unloading paddle and a material dropping chute at the material unloading position, the bottom side of the material unloading paddle is higher than the top surface of the tray and lower than the top surface of the magnetic core, the inner end of the material unloading paddle is close to the inner side of the tray, the outer end of the material unloading paddle protrudes out of the edge of the turntable and is inclined in the rotation direction of the turntable, the top side of the material dropping chute is located below the tray, the inner end of the material unloading chute is arranged close to the rotating drum, and a vertical plate is provided on the side of the material unloading chute away from the material unloading paddle, the bottom of the material unloading chute is an inclined slope, and the side close to the vertical plate is the lowest side.

9. A soft magnetic core visual inspection system according to claim 8, characterized in that: A reject position is also provided between the thermal imaging position and the unloading position of the turntable, and the turntable is provided with a reject paddle and a reject chute at the reject position, the inner end of the reject paddle is close to the inner side of the tray, the outer end of the reject paddle protrudes from the edge of the turntable and is inclined in the rotation direction of the turntable, the outer end of the reject paddle is fixed on the lifting rod, when the lifting rod is raised, the bottom side of the reject paddle is higher than the top surface of the magnetic core, when the lifting rod falls, the bottom side of the reject paddle is close to the top surface of the tray, the top side of the reject chute is located below the tray, the inner end of the reject chute is arranged close to the rotating drum, and a vertical plate is provided on the side of the reject chute away from the unloading paddle, the bottom of the reject chute is an inclined slope and the side close to the vertical plate is the lowest side.

10. A soft magnetic core visual inspection system according to claim 2, characterized in that: It also includes a material preparation module, which has a material preparation trough, one end of which is provided with a chute connected thereto, the chute is a straight trough and the end away from the material preparation trough is provided with a flat trough, the trough width of the chute and the trough width of the flat trough are both adapted to the outer diameter of the magnetic core, the trough bottom of the chute and the trough bottom of the material preparation trough are coplanar and are both inclined toward one end of the flat trough, an arc-shaped baffle is provided at the end of the flat trough away from the chute, the arc-shaped baffle is semicircular, the inner diameter of the arc-shaped baffle corresponds to the outer diameter of the magnetic core, the bottom of the flat trough is provided with a strip opening, the width of the strip opening is greater than the inner diameter of the magnetic core.

Images