A method and device for detecting defects in electrolytic capacitors

Abstract

The present invention provides an electrolytic capacitor defect detection method and a detection device thereof, which relate to the technical field of capacitor appearance detection, and include the following steps: a 3D camera line scans a rotating electrolytic capacitor to obtain a surface depth map of the electrolytic capacitor; a Fourier series is used, with the number of image rows as a period, to periodically extend the grayscale value of each column of pixels in the surface depth map; the Fourier coefficient is calculated, and the grayscale value curve of each column of pixels in the surface depth map is fitted to obtain an ideal depth map of the surface; the ideal grayscale value obtained by fitting is compared with the actual grayscale value, and the deviation is calculated; the defect position is determined according to the deviation position coordinates, and the defect type is determined according to the deviation size. The present invention can solve the problem that in the process of the rotating table rotating in the prior art, the capacitor placed on the rotating table is deviated from the original position due to the centrifugal force brought by the rotation, thereby making the image information obtained by the industrial camera inaccurate and easily ignoring the defects on the side of the capacitor, and realizes accurate identification of defects on the surface of the capacitor.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitor appearance detection, and in particular to an electrolytic capacitor defect detection method and a detection device thereof. Background Art

[0002] During the production process, electrolytic capacitors are prone to many defects, such as scratches and swelling. Manual inspection of the capacitor's appearance is required to ensure the quality of the capacitor. However, manual inspection requires a lot of manpower and is prone to missed inspections and false inspections.

[0003] In this regard, Chinese patent application No. 201410064017.3 discloses a capacitor detection system and method based on machine vision. The capacitor detection system includes a device size determination subsystem, a capacity measurement subsystem, a capacitor capacitance testing system, a capacitor appearance defect detection system, a qualified capacitor automatic packaging system, an unqualified capacitor classification and rejection system, a pin correction device subsystem, a side defect detection subsystem, a bottom defect detection subsystem, a pin defect detection subsystem, and a top defect detection subsystem. One or more of the following; the side defect detection subsystem provided by the above patent uses an industrial camera, a light source, a laser measurement system, and a rotating table to identify defects on the side of the capacitor.

[0004] When using the side defect detection subsystem provided by the above patent, it is necessary to place the capacitor on a rotating table and rotate the rotating table so that the industrial camera can obtain images of the surrounding side of the capacitor, and then process and judge the defects on the side of the capacitor through an algorithm; however, during the rotation of the rotating table, the capacitor placed on the rotating table will deviate from its original position due to the centrifugal force caused by the rotation, thereby making the image information obtained by the industrial camera inaccurate, and the depth image taken will be displayed as different light and dark areas, which can easily overlook the defects on the side of the capacitor. Summary of the invention

[0005] In response to the above-mentioned problems, the present invention provides an electrolytic capacitor defect detection method, which can solve the problem that during the rotation of the rotating table, the capacitor placed on the rotating table will deviate from its original position due to the centrifugal force caused by the rotation, thereby making the image information obtained by the industrial camera inaccurate and easily ignoring the defects on the side of the capacitor, thereby achieving accurate identification of defects on the surface of the capacitor.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The present invention provides a method for detecting defects in electrolytic capacitors, comprising the following steps:

[0008] S101: The 3D camera scans the rotating electrolytic capacitor to obtain a surface depth map of the electrolytic capacitor;

[0009] S102: taking the grayscale value of each column of pixels in the surface depth map as a reference object, using the Fourier series of the trigonometric function system, taking the number of image rows as a period, periodically extending the grayscale value of each column of pixels in the surface depth map; using trapezoidal area integral to approximate the Fourier coefficient, fitting the grayscale value curve of each column of pixels in the surface depth map, thereby obtaining the ideal grayscale value of each column of pixels in the surface depth map, and then obtaining the ideal depth map of the surface;

[0010] S103: Taking a column of pixels of the ideal depth map of the surface as a reference object, starting from the first column of pixels of the ideal depth map of the surface and ending at the last column of pixels of the ideal depth map of the surface, the ideal grayscale value obtained by fitting is compared with the actual grayscale value, and a deviation value is calculated; a single-channel image with equal grayscale values ​​is regenerated, which is the same size as the surface depth map; according to the position where the deviation value is generated on the surface depth map, the deviation value is added to the grayscale value at the same position of the regenerated single-channel image to obtain the flattened depth map of the surface; the defect position is determined according to the position of the grayscale value change on the flattened depth map of the surface, and the defect type is determined according to the deviation size.

[0011] The electrolytic capacitor defect detection method provided by the present invention, preferably, in step S102, the method of periodically extending the grayscale value of each column of pixel points in the surface depth map comprises the following steps:

[0012] S201: using a row of the surface depth map as an x-coordinate and a grayscale value of the x-th row corresponding to a column in the surface depth map as a y-coordinate, thereby obtaining a continuous curve consisting of (x, y) with a limited range of x values;

[0013] S202: Taking the number of rows of the surface depth map as a period, the period is recorded as T, and periodically extending the topology curve to make it a periodic function curve with an infinite range of x values ​​and a period of T; the periodic function is expressed as:

[0014] Where f(t) is the function being fitted, and t refers to the value of x; a0、a n and b n are the Fourier coefficients.

[0015] The electrolytic capacitor defect detection method provided by the present invention preferably comprises:

[0016]

[0017] The value of t0 is 0, which refers to the beginning of the cycle; t0+T refers to any cycle.

[0018] In the electrolytic capacitor defect detection method provided by the present invention, preferably, in step S103, the grayscale value of the single-channel image is 125.

[0019] The present invention provides an electrolytic capacitor defect detection device using the electrolytic capacitor defect detection method, comprising a 3D camera, a driving mechanism and a negative suction component; the negative suction component comprises a negative suction pump and a connecting piece; the connecting piece is vertically arranged; the bottom of the connecting piece is rotatably fixed to the suction port of the negative suction pump; the driving mechanism drives the connecting piece to rotate;

[0020] The interior of the connecting piece is hollow; an opening is provided at the bottom of the connecting piece; the opening is connected to the air inlet of the negative suction pump; the top of the connecting piece is planar; a plurality of openings are provided at the top of the connecting piece; the openings are connected to the openings;

[0021] The 3D camera and the connecting member are located on the same straight line.

[0022] The electrolytic capacitor defect detection device provided by the present invention preferably comprises a driving mechanism comprising a motor, a first pulley, a second pulley and a belt; the first pulley is fixed to the connecting member; the axis of the first pulley coincides with the axis of the connecting member; the output shaft of the motor is arranged upward; the second pulley is fixed to the output shaft of the motor; the axis of the second pulley coincides with the axis of the output shaft of the motor; the first pulley and the second pulley are at the same height; the first pulley and the second pulley are connected in transmission via the belt.

[0023] The electrolytic capacitor defect detection device provided by the present invention preferably further comprises an XY adjustment platform for adjusting the horizontal position of the 3D camera; the 3D camera is fixed to the upper surface of the XY adjustment platform.

[0024] The electrolytic capacitor defect detection device provided by the present invention preferably also includes a diffuse reflection plate; the plate surface of the diffuse reflection plate faces the 3D camera; the 3D camera, the connecting member and the diffuse reflection plate are in the same straight line; the connecting member is located between the 3D camera and the diffuse reflection plate.

[0025] In the electrolytic capacitor defect detection device provided by the present invention, preferably, the negative suction component also includes a single-channel rotary joint; the connecting piece is connected to the suction port of the negative suction pump through the single-channel rotary joint.

[0026] The electrolytic capacitor defect detection device provided by the present invention preferably also includes a clamping jaw assembly for clamping the electrolytic capacitor; the clamping jaw assembly is arranged above the connecting piece; the clamping jaw assembly includes a clamping jaw and a clamping jaw arm; the clamping jaw is fixed to the clamping jaw arm; and the clamping jaw is arranged horizontally.

[0027] The above technical solution has the following advantages or beneficial effects:

[0028] The electrolytic capacitor defect detection method provided by the present invention comprises: in step S101, a 3D camera is used to perform line scanning on the curved side wall of the electrolytic capacitor, and a curved depth map of the electrolytic capacitor is obtained by splicing;

[0029] In step S102, the grayscale values ​​of each column of pixels in the surface depth map are taken as the operation objects, and the grayscale values ​​of each column of pixels are formed into a curve. By adopting the Fourier series and taking the number of image rows as the period, the grayscale values ​​of each column of pixels in the surface depth map are extended, thereby extending the curve formed by the grayscale values ​​of each column of pixels; further, the trapezoidal area integral is used to approximate the Fourier coefficient, and the grayscale value curve of each column in the surface depth map is fitted, so as to obtain the grayscale value of each column of pixels in the surface depth map after fitting, and then obtain the ideal depth map of the surface, which is the ideal image of the defect-free electrolytic capacitor at this eccentric position;

[0030] In step S103, the grayscale value of each column of pixels in the ideal depth map of the surface is compared with the grayscale value of each column of pixels in the surface depth map to obtain the deviation value of the grayscale value; a single-channel image with equal grayscale values ​​is regenerated, which is the same size as the surface depth map; because when calculating the deviation value, the grayscale value of each column of pixels in the ideal depth map of the surface is compared with the grayscale value of each column of pixels in the surface depth map, and the deviation value is obtained by comparing the grayscale values ​​of two pixels at the same position, the position of the deviation value is the same as the position of the surface depth map, and according to the position where the deviation value is generated on the surface depth map, the grayscale value at the same position of the regenerated single-channel image is added with the deviation value. The deviation is positive or negative. Under the same gray value, the deviation value is added to clearly reflect the position where the gray value changes. The position of the defect is directly obtained by obtaining the deviation value between the ideal depth map of the surface and the depth map of the surface, thereby avoiding the influence of the light and dark relationship of the surface on the defect information, thereby reducing the influence of the electrolytic capacitor deviating from the original position due to the centrifugal force. The flattened depth map of the surface is obtained. The flattened depth map of the surface maps the defect information of the curved surface onto the plane, and the position of the defect is determined according to the position of the gray value change on the flattened depth map of the surface, and the type of the defect is determined according to the numerical value of the deviation. Furthermore, the capacitor concave and convex defect area is extracted in the flattened depth map of the surface through threshold processing;

[0031] The electrolytic capacitor defect detection method provided by the present invention obtains a surface depth map and fits the surface depth map to obtain an ideal surface depth map of a defect-free capacitor at this eccentric position, calculates the deviation value between the surface depth map and the ideal surface depth map, and directly obtains the position information of the defect, thereby avoiding the light and dark interference of the image information caused by the centrifugal force when the capacitor rotates, and realizing accurate identification of defects on the surface of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention and its features, configurations and advantages will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings. The same reference numerals indicate the same parts throughout the drawings. The drawings are not drawn to scale, but rather to illustrate the subject matter of the present invention.

[0033] Figure 1 This is a flow chart of an electrolytic capacitor defect detection method provided in Example 1 of the present invention.

[0034] Figure 2 This is a flow chart of a method for periodically extending the grayscale value of each column of pixels in a surface depth map provided in Example 1 of the present invention.

[0035] Figure 3 It is a schematic diagram of the three-dimensional structure of an electrolytic capacitor defect detection device provided in Example 2 of the present invention.

[0036] Figure 4 It is a schematic diagram of the internal structure of an electrolytic capacitor defect detection device provided in Example 2 of the present invention.

[0037] Figure 5 yes Figure 4 The structural diagram of the belt is omitted. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0039] Embodiment 1:

[0040] like Figure 1 As shown, a method for detecting electrolytic capacitor defects provided by Embodiment 1 of the present invention includes the following steps:

[0041] S101: The 3D camera scans the rotating electrolytic capacitor to obtain a surface depth map of the electrolytic capacitor;

[0042] S102: taking the grayscale value of each column of pixels in the surface depth map as a reference object, using the Fourier series of the trigonometric function system, taking the number of image rows as a period, periodically extending the grayscale value of each column of pixels in the surface depth map; using trapezoidal area integral to approximate the Fourier coefficient, fitting the grayscale value curve of each column of pixels in the surface depth map, thereby obtaining the ideal grayscale value of each column of pixels in the surface depth map, and then obtaining the ideal depth map of the surface;

[0043] S103: Taking a column of pixels of the ideal depth map of the surface as a reference object, starting from the first column of pixels of the ideal depth map of the surface and ending at the last column of pixels of the ideal depth map of the surface, the ideal grayscale value obtained by fitting is compared with the actual grayscale value, and a deviation value is calculated; a single-channel image with equal grayscale values ​​is regenerated, which is the same size as the surface depth map; according to the position where the deviation value is generated on the surface depth map, the deviation value is added to the grayscale value at the same position of the regenerated single-channel image to obtain the flattened depth map of the surface; the defect position is determined according to the grayscale change position on the flattened depth map of the surface, and the defect type is determined according to the deviation size.

[0044] In the electrolytic capacitor defect detection method provided in Embodiment 1 of the present invention, in step S101, a 3D camera is used to perform line scanning on the curved side wall of the electrolytic capacitor, and a curved depth map of the electrolytic capacitor is obtained by stitching;

[0045] In step S102, the grayscale values ​​of each column of pixels in the surface depth map are taken as the operation objects, and the grayscale values ​​of each column of pixels are formed into a curve. By adopting the Fourier series and taking the number of image rows as the period, the grayscale values ​​of each column of pixels in the surface depth map are extended, thereby extending the curve formed by the grayscale values ​​of each column of pixels; further, the trapezoidal area integral is used to approximate the Fourier coefficient, and the grayscale value curve of each column in the surface depth map is fitted, so as to obtain the grayscale value of each column of pixels in the surface depth map after fitting, and then obtain the ideal depth map of the surface, which is the ideal image of the defect-free electrolytic capacitor at this eccentric position;

[0046] In step S103, the grayscale value of each column of pixels in the ideal depth map of the surface is compared with the grayscale value of each column of pixels in the surface depth map to obtain the deviation value of the grayscale value; a single-channel image with equal grayscale values ​​is regenerated, which is the same size as the surface depth map; because when calculating the deviation value, the grayscale value of each column of pixels in the ideal depth map of the surface is compared with the grayscale value of each column of pixels in the surface depth map, and the deviation value is obtained by comparing the grayscale values ​​of two pixels at the same position, the position of the deviation value is the same as the position of the surface depth map, and according to the position where the deviation value is generated on the surface depth map, the grayscale value at the same position of the regenerated single-channel image is added with the deviation value. The deviation is positive or negative. Under the same gray value, the deviation value is added to clearly reflect the position where the gray value changes. The position of the defect is directly obtained by obtaining the deviation value between the ideal depth map of the surface and the depth map of the surface, thereby avoiding the influence of the light and dark relationship of the surface on the defect information, thereby reducing the influence of the electrolytic capacitor deviating from the original position due to the centrifugal force. The flattened depth map of the surface is obtained. The flattened depth map of the surface maps the defect information of the curved surface onto the plane, and the position of the defect is determined according to the position of the gray value change on the flattened depth map of the surface, and the type of the defect is determined according to the numerical value of the deviation. Furthermore, the capacitor concave and convex defect area is extracted in the flattened depth map of the surface through threshold processing;

[0047] The electrolytic capacitor defect detection method provided by the present invention obtains a surface depth map and fits the surface depth map to obtain an ideal surface depth map of a defect-free capacitor at this eccentric position, calculates the deviation value between the surface depth map and the ideal surface depth map, and directly obtains the position information of the defect, thereby avoiding the light and dark interference of the image information caused by the centrifugal force when the capacitor rotates, and realizing accurate identification of defects on the surface of the capacitor.

[0048] like Figure 2 As shown, the electrolytic capacitor defect detection method provided by Embodiment 1 of the present invention, preferably, in step S102, the method of periodically extending the grayscale value of each column of pixel points in the surface depth map includes the following steps:

[0049] S201: using a row of the surface depth map as an x-coordinate and a grayscale value of the x-th row corresponding to a column in the surface depth map as a y-coordinate, thereby obtaining a continuous curve consisting of (x, y) with a limited range of x values;

[0050] S202: Taking the number of rows of the surface depth map as a period, the period is recorded as T, and periodically extending the topology curve to make it a periodic function curve with an infinite range of x values ​​and a period of T; the periodic function is expressed as:

[0051] Where f(t) is the fitted function, and t refers to the value of x; a0、an and b n are the Fourier coefficients.

[0052] In the electrolytic capacitor defect detection method provided in Example 1 of the present invention, in step S201, a column of pixel points in the surface depth map is selected, and the row index of the column of pixel points in the surface depth map is used as the x coordinate, the row index starts from 0 to row-1, and row is the row number of the surface depth map; the gray value of the pixel point in the xth row of the column is used as the y coordinate, the value range of y is 0 to 255, x and y constitute a group of (x, y) points, and the group of (x, y) points forms a continuous curve with a limited range of x values;

[0053] In step S202, the number of rows of the surface depth map is taken as a period, and the period is denoted as T. The topological curve is periodically extended to make it a periodic function curve with an infinite range of x values ​​and a period of T, thereby satisfying the use conditions of the Fourier series. By solving the Fourier coefficients, the fitting function of the gray value curve of each column of pixels in the surface depth map is obtained, and then the ideal gray value of the pixel column in the surface depth map is obtained, and finally a complete ideal depth map of the surface is obtained.

[0054] The electrolytic capacitor defect detection method provided in Embodiment 1 of the present invention is preferably:

[0055]

[0056] The value of t0 is 0, which refers to the beginning of the cycle; t0+T refers to any cycle.

[0057] The electrolytic capacitor defect detection method provided in embodiment 1 of the present invention is based on a n Take b as an example, n The process of obtaining is similar;

[0058] Right now

[0059] By expanding the summation formula, it is calculated as follows:

[0060]

[0061] Where f(0) is the grayscale value of the first pixel in the selected column in the surface depth map, and so on, f(T-1) is the grayscale value of the Tth pixel in the selected column in the surface depth map, so as to calculate a n and b n The general solution of n and b n Substitute f(t) into the fitting function to obtain the grayscale value of each column of pixels in the ideal depth map of the surface, and obtain the complete ideal depth map of the surface.

[0062] In the electrolytic capacitor defect detection method provided in Example 1 of the present invention, preferably, in step S103, the grayscale value of the single-channel image is 125, and when the deviation value is added to the grayscale value of the pixel point in the single-channel image, the added grayscale value needs to be greater than or equal to 0 and less than or equal to 255; when the grayscale value is 125, the grayscale value is kept within a reasonable value range.

[0063] Embodiment 2:

[0064] On the basis of Example 1, in order to further provide a technical effect of effectively identifying defects on the surface of a capacitor, Example 2 of the present invention provides an electrolytic capacitor defect detection device that uses the electrolytic capacitor defect detection method in Example 1, such as Figure 3-Figure 4 As shown, it includes a 3D camera 1, a driving mechanism 2 and a negative suction component 3; the negative suction component 3 includes a negative suction pump and a connecting member 31; the connecting member 31 is vertically arranged; the bottom of the connecting member 31 is rotatably fixed to the suction port of the negative suction pump; the driving mechanism 2 drives the connecting member 31 to rotate;

[0065] The interior of the connecting member 31 is hollow; an opening 311 is provided at the bottom of the connecting member 31; the opening 311 is connected to the air inlet of the negative suction pump; the top of the connecting member 31 is planar; a plurality of openings 312 are provided at the top of the connecting member 31; the openings 311 are connected to the openings 312;

[0066] The 3D camera 1 and the connecting member 31 are located on the same straight line.

[0067] When using the electrolytic capacitor defect detection device provided by Example 2 of the present invention, the electrolytic capacitor is placed on the top plane of the connector 31; the negative suction pump is started, and the negative suction pump draws air from the air inlet to form a negative pressure, and the opening 311 is connected to the negative suction pump, so that a negative pressure is formed at the opening 312; when the electrolytic capacitor is placed on the top plane of the connector 31, the negative pressure formed at the opening 312 adsorbs the bottom of the electrolytic capacitor; the driving mechanism 2 controls the connector 31 to rotate, and the electrolytic capacitor adsorbed on the top plane of the connector 31 rotates with the connector 31; the 3D camera 1 scans the side of the electrolytic capacitor during rotation to obtain a surface depth map of the electrolytic capacitor.

[0068] The electrolytic capacitor defect detection device provided in Example 2 of the present invention, because in the prior art, during the rotation of the rotating table, the capacitor placed on the rotating table will be deviated from the original position due to the centrifugal force caused by the rotation, thereby making the image information obtained by the industrial camera inaccurate and easily ignoring the defects on the side of the capacitor. Therefore, it is necessary to reduce the influence of the centrifugal force on the capacitor; for this reason, the electrolytic capacitor defect detection device also includes a negative suction component 3; the negative suction component 3 includes a negative suction pump and a connecting piece 31, and the negative suction pump is not shown in the accompanying drawings; the bottom of the connecting piece 31 is rotatably fixed to the air suction port of the negative suction pump, and the inside of the connecting piece 31 is hollow, and the bottom of the connecting piece 31 is provided with an opening 311, and the opening 311 is connected to the air suction port of the negative suction pump , so that the negative pressure of the negative suction pump can act on the connecting member 31; a plurality of openings 312 are provided on the top of the connecting member 31, so that the opening 311 is connected with the openings 312, so that the negative pressure generated by the negative suction pump acts on the top of the connecting member 31 through the openings 312; further, in order to place the electrolytic capacitor stably on the top of the connecting member 31, the top of the connecting member 31 is made to be planar; when the electrolytic capacitor is placed on the top plane of the connecting member 31, the bottom of the electrolytic capacitor is adsorbed on the top of the connecting member 31 by the negative pressure generated by the openings 312, thereby reducing the influence of the centrifugal force generated by the driving mechanism 2 driving the connecting member 31 to rotate, thereby enabling the 3D camera to more accurately obtain the image information of the electrolytic capacitor.

[0069] like Figure 4-Figure 5 As shown, the electrolytic capacitor defect detection device provided by Example 2 of the present invention preferably comprises a motor 21, a first pulley 22, a second pulley 23 and a belt 24 in order to drive the connecting member 31 to rotate; the first pulley 22 is fixed to the connecting member 31 so that the axis of the first pulley 22 coincides with the axis of the connecting member 31, and when the first pulley 22 rotates, the connecting member 31 is driven to rotate; the output shaft of the motor 21 is arranged upward so that the second pulley 23 is fixed to the output shaft of the motor 21, and the axis of the second pulley 23 coincides with the axis of the output shaft of the motor 21, and when the output shaft of the motor 21 rotates, the second pulley 23 follows The output shaft of the motor 21 rotates; in order to make the belt 24 encircle the first pulley 22 and the second pulley 23 at the same height, when the wheel surface of the first pulley 22 contacts the inner ring of the belt, and the wheel surface of the second pulley 23 contacts the inner ring of the belt 24, the belt is in a taut state. At this time, the first pulley 22 and the second pulley 23 are connected by the belt 24, and the second pulley 23 is driven by the rotating shaft of the motor 21 to rotate, and the second pulley 23 drives the belt 24 to rotate, and the belt 24 drives the first pulley 22 to rotate, thereby driving the connecting member 31 to rotate, and then driving the electrolytic capacitor to rotate.

[0070] like Figure 3As shown, the electrolytic capacitor defect detection device provided in Example 2 of the present invention preferably also includes an XY adjustment platform 4 for adjusting the horizontal position of the 3D camera 1; here, the XY adjustment platform 4 is the XY adjustment platform provided in the Chinese patent No. 202221480935.0; the 3D camera 1 is fixed on the upper surface of the XY adjustment platform 4; when the 3D camera 1 is fixed on the XY adjustment platform 4, the shooting direction of the 3D camera 1 on the horizontal plane is effectively adjusted through the XY adjustment platform 4, so that the 3D camera 1 can more accurately obtain the image information of the electrolytic capacitor.

[0071] like Figure 3 As shown, the electrolytic capacitor defect detection device provided by Example 2 of the present invention preferably emits a laser for scanning when the 3D camera 1 shoots the product. In order to prevent light pollution from affecting the shooting of other cameras, the electrolytic capacitor defect detection device also includes a diffuse reflection plate 5. The plate surface of the diffuse reflection plate 5 faces the 3D camera 1, and the 3D camera 1, the connecting member 31 and the diffuse reflection plate 5 are on the same straight line. The connecting member 31 is located between the 3D camera 1 and the diffuse reflection plate 5. When the 3D camera 1 shoots the electrolytic capacitor placed on the top of the connecting member 31, the diffuse reflection plate 5 blocks the excessive laser emitted by the 3D camera 1. When multiple groups of electrolytic capacitor defect detection devices are running at the same time, the laser emitted by the 3D camera 1 is prevented from interfering with the detection of electrolytic capacitors by 3D cameras 1 of other groups.

[0072] like Figure 4-Figure 5 As shown, in the electrolytic capacitor defect detection device provided by Example 2 of the present invention, preferably, the negative suction component 3 also includes a single-channel rotary joint 32; the connecting member 31 is connected to the suction port of the negative suction pump through the single-channel rotary joint 32, and the negative suction pump is not shown in the accompanying drawings. At this time, the connecting member 31 rotates relative to the single-channel rotary joint 32, and the connecting part of the single-channel rotary joint 32 and the suction port of the negative suction pump does not rotate, and air enters from the opening 312 at the top of the connecting member 31, enters the single-channel rotary joint 32 from the opening 311 at the bottom of the connecting member 31, and enters the suction port of the negative suction pump from the single-channel rotary joint 32, thereby forming a negative pressure at the opening 312 at the top of the connecting member 31, and generating suction.

[0073] like Figure 3-Figure 5As shown, the electrolytic capacitor defect detection device provided in Example 2 of the present invention preferably also includes a clamping jaw assembly 6 for clamping the electrolytic capacitor in order to automatically clamp the electrolytic capacitor onto the top plane of the connector 31; the clamping jaw assembly 6 is arranged above the connector 31, so as to avoid the clamping jaw assembly 6 colliding with the connector 31 when clamping the electrolytic capacitor; the clamping jaw assembly 6 includes a clamping jaw 61 and a clamping jaw arm 62, the clamping jaw 61 is fixed to the clamping jaw arm 62, and the clamping jaw 61 is controlled to open or close by the clamping jaw arm 62; further, the clamping jaw 61 is arranged horizontally, and when the clamping jaw 61 clamps the electrolytic capacitor, the clamping jaw 61 clamps the curved side wall of the electrolytic capacitor to avoid the clamping jaw 61 touching the lead of the electrolytic capacitor, thereby avoiding wear of the electrolytic capacitor.

[0074] In summary, the electrolytic capacitor defect detection method provided by the present invention can solve the problem in the prior art that during the rotation of the rotating table, the capacitor placed on the rotating table will deviate from its original position due to the centrifugal force caused by the rotation, thereby making the image information obtained by the industrial camera inaccurate and easily ignoring the defects on the side of the capacitor, thereby achieving accurate identification of defects on the surface of the capacitor.

[0075] Those skilled in the art should understand that those skilled in the art can implement the above-mentioned variations by combining the prior art and the above-mentioned embodiments, which will not be described in detail here. Such variations do not affect the essential content of the present invention, and will not be described in detail here.

[0076] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above-mentioned specific embodiments, and the devices and structures that are not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art can make many possible changes and modifications without departing from the technical solution of the present invention, or modify them into equivalent embodiments with equivalent changes, which does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A method for detecting defects in electrolytic capacitors, characterized in that: The following steps are involved: S101: The 3D camera scans the rotating electrolytic capacitor to obtain a surface depth map of the electrolytic capacitor; S102: taking the grayscale value of each column of pixels in the surface depth map as a reference object, using the Fourier series of the trigonometric function system, taking the number of image rows as a period, periodically extending the grayscale value of each column of pixels in the surface depth map; using trapezoidal area integral to approximate the Fourier coefficient, fitting the grayscale value curve of each column of pixels in the surface depth map, thereby obtaining the ideal grayscale value of each column of pixels in the surface depth map, and then obtaining the ideal depth map of the surface; S103: taking a column of pixels in the ideal depth map of the surface as a reference object, starting from the first column of pixels in the ideal depth map of the surface and ending at the last column of pixels in the ideal depth map of the surface, comparing the ideal grayscale value obtained by fitting with the actual grayscale value, and calculating the deviation value; regenerating a single-channel image with equal grayscale values, which is equal in size to the surface depth map; adding the deviation value to the grayscale value at the same position of the regenerated single-channel image according to the position where the deviation value is generated on the surface depth map, so as to obtain the flattened depth map of the surface; judging the defect position according to the grayscale value change position on the flattened depth map of the surface, and judging the defect type according to the deviation size; The method for periodically extending the grayscale value of each column of pixels in the surface depth map in step S102 comprises the following steps: S201: using a row of the surface depth map as an x-coordinate and a grayscale value of the x-th row corresponding to a column in the surface depth map as a y-coordinate, thereby obtaining a continuous curve consisting of (x, y) with a limited range of x values; S202: Taking the number of rows of the surface depth map as a period, the period is recorded as T, and periodically extending the topology curve to make it a periodic function curve with an infinite range of x values ​​and a period of T; the periodic function is expressed as: Where f(t) is the function being fitted, and t refers to the value of x; a0、a n and b n are the Fourier coefficients.

2. The electrolytic capacitor defect detection method according to claim 1, characterized in that: The value of t0 is 0, which refers to the beginning of the cycle; t0+T refers to any cycle.

3. The electrolytic capacitor defect detection method according to claim 1, characterized in that: In step S103, the grayscale value of the single-channel image is 125.

4. An electrolytic capacitor defect detection device using the electrolytic capacitor defect detection method according to any one of claims 1 to 3, characterized in that: It includes a 3D camera, a driving mechanism and a negative suction component; the negative suction component includes a negative suction pump and a connecting piece; the connecting piece is vertically arranged; the bottom of the connecting piece is rotatably fixed to the suction port of the negative suction pump; the driving mechanism drives the connecting piece to rotate; The interior of the connecting piece is hollow; an opening is provided at the bottom of the connecting piece; the opening is connected to the air inlet of the negative suction pump; the top of the connecting piece is planar; a plurality of openings are provided at the top of the connecting piece; the openings are connected to the openings; The 3D camera and the connecting member are located on the same straight line.

5. The electrolytic capacitor defect detection device according to claim 4, characterized in that: The driving mechanism includes a motor, a first pulley, a second pulley and a belt; the first pulley is fixed to the connecting member; the axis of the first pulley coincides with the axis of the connecting member; the output shaft of the motor is arranged upward; the second pulley is fixed to the output shaft of the motor; the axis of the second pulley coincides with the axis of the output shaft of the motor; the first pulley and the second pulley are at the same height; the first pulley and the second pulley are connected in transmission through the belt.

6. The electrolytic capacitor defect detection device according to claim 4, characterized in that: It also includes an XY adjustment platform for adjusting the horizontal position of the 3D camera; the 3D camera is fixed on the upper surface of the XY adjustment platform.

7. The electrolytic capacitor defect detection device according to claim 4, characterized in that: It also includes a diffuse reflection plate; the plate surface of the diffuse reflection plate faces the 3D camera; the 3D camera, the connecting member and the diffuse reflection plate are on the same straight line; the connecting member is located between the 3D camera and the diffuse reflection plate.

8. The electrolytic capacitor defect detection device according to claim 4, characterized in that: The negative suction component also includes a single-channel rotating joint; the connecting piece is connected to the suction port of the negative suction pump through the single-channel rotating joint.

9. The electrolytic capacitor defect detection device according to claim 4, characterized in that: It also includes a clamping jaw assembly for clamping the electrolytic capacitor; the clamping jaw assembly is arranged above the connecting piece; the clamping jaw assembly includes a clamping jaw and a clamping jaw arm; the clamping jaw is fixed to the clamping jaw arm; and the clamping jaw is arranged horizontally.

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