A method for visual inspection of the quality of a film roll

Abstract

The application discloses a film winding quality visual detection method, and relates to the technical field of film winding process. The method determines different winding core circumferential positions uniformly distributed on the winding core according to a required total shooting frequency, and then combines winding attribute parameters to calculate each shooting moment reaching the corresponding winding core circumferential position and satisfying a minimum time interval. The film winding image at the corresponding winding core circumferential position can be obtained by triggering the camera shooting based on the shooting moment, so that uniform shooting can be realized in the winding process, the phenomenon of periodic overlapping of shooting positions is avoided, and the film winding quality at different circumferential positions can be evaluated, thereby improving the reliability and robustness of the film winding quality visual detection.

Description

Technical Field

[0001] This application relates to the field of membrane winding technology, and in particular to a visual inspection method for membrane winding quality. Background Technology

[0002] In film manufacturing and subsequent processing industries such as plastic film, metal coating, lithium battery separator, and adhesive tape (such as printing, coating, and slitting), winding is a key process that determines the appearance and quality of the final product. When the winding motor drives the winding shaft to rotate the core, the winding shaft winds the film onto the core to form a roll. However, due to various factors such as unwinding tension fluctuations, guide roller parallelism deviations, uneven film thickness, or changes in material properties, the film is very prone to lateral position deviation on the travel path, i.e., "deviation" or "skewness". Even with a correction system, instantaneous or local skewness can still occur during the winding process.

[0003] Such winding skew can lead to uneven winding, potentially causing problems such as material jamming, breakage, and waste in subsequent processes, and even damaging expensive production equipment. It can also affect the appearance quality and market competitiveness of the product. Therefore, it is necessary to monitor and record the winding skew during the winding process. On the one hand, this can be used to judge and grade the quality of the roll material; on the other hand, it can also provide feedback and closed-loop control during the winding process to adaptively correct skew and improve winding quality.

[0004] Currently, the most common method for detecting film winding quality is through visual inspection. An industrial camera is fixed at the winding station, and it captures end-face images at fixed time intervals or synchronously with the winding encoder. The deviation of the current layer is then calculated using image processing algorithms. However, this approach only captures the instantaneous state of a tiny angle on the winding circumference, which is highly unpredictable and provides a one-sided assessment, failing to accurately evaluate the overall winding quality of the entire loop or even the entire winding section. Summary of the Invention

[0005] This application addresses the aforementioned problems and technical requirements by proposing a visual inspection method for film winding quality. The technical solution of this application is as follows: A visual inspection method for film winding quality, the method comprising: Initialization start time And determine the total number of shots. ; Determine that the components are evenly distributed along the circumference of the roll core on the cross section of the roll core where the camera is positioned. The circumferential position of each core; Initialization parameters During the winding process, the timing relative to the previous shooting time is determined based on the winding attribute parameters. Reaching the minimum time interval After that, the first rotation to the 1st The moment when the circumferential position of the roll core reaches the camera's shooting position is taken as the first... Each shooting moment , The previous shooting moment The starting time ; According to the Each shooting moment Trigger camera to acquire the first The film winding image is captured and visual inspection of the film winding quality is performed. And reaffirm the first The shooting moment until .

[0006] A further technical solution is that the visual inspection method for film winding quality also includes: On the cross section of the roll core where the camera is positioned, using the line connecting the center of the cross section and the camera position at time 0 as a baseline, determine the point from the baseline by rotating counterclockwise around the center of the cross section to the point where the camera position is at time 0. The included angle between the lines connecting the circumferential positions of each core is obtained. The basic phase angle of each core circumferential position and based on the first The basic phase angle of each core circumferential position Determine the first Several shooting moments; among them It is the initial phase angle.

[0007] Its further technical solution is based on the first The basic phase angle of each core circumferential position Determine the first Each shooting moment include: Based on the winding attribute parameters and the first The basic phase angle of each core circumferential position Determine the first rotation to the th from time 0. The equivalent winding radius when the circumferential position of the roll core reaches the camera's shooting position. ; Based on satisfying the minimum time interval Minimum time required The minimum time is determined by combining the winding attribute parameters. The target equivalent winding radius at time ; Determine the first rotation to the [number]th time starting from time 0. Complete the circumferential position of each core before finishing. The coil winding operation allows for winding from the equivalent winding radius. Increase to the first time the target equivalent winding radius is reached The moment as the first Each shooting moment Integer parameters .

[0008] A further technical solution is that the winding attribute parameters include at least the core radius. membrane thickness winding speed Length of winding at time 0 Determine the equivalent winding radius Equivalent winding radius to target include: Based on the core radius membrane thickness as well as The length of the coil at that time Determine the equivalent winding radius at time 0. ; Based on the equivalent winding radius at time 0 Combined with the first The basic phase angle of each core circumferential position Determine the equivalent winding radius ; Based on the equivalent winding radius at time 0 Combining the minimum time and winding speed Determine the target equivalent winding radius .

[0009] Its further technical solution is to determine the equivalent winding radius. .

[0010] Its further technical solution is to determine the target equivalent winding radius. for: Based on winding speed Determine the time from time 0 to the minimum time. Total winding length And determine the target equivalent winding radius. .

[0011] Its further technical solution is to determine the first Each shooting moment include: Calculate from equivalent winding radius Increase to the target equivalent winding radius Required number of laps And calculate the first rotation from time 0 to the [missing value]. Complete the circumferential position of each core before finishing. Total winding length during winding Combined with winding speed Determine the total winding length has been reached. The time taken to obtain the first Each shooting moment .

[0012] Its further technical solution is to determine the first Each shooting moment include: calculate ; when Time to determine Otherwise confirm , Indicates rounding up. It is a threshold; Based on the calculated number of laps Perform cyclic verification to determine the first Each shooting moment .

[0013] Its further technical solution is based on the calculated number of full laps. Perform cyclic verification to determine the first Each shooting moment include: When based on the currently determined number of laps The calculation of the first Each shooting moment season And based on the updated number of laps Recalculate the first Each shooting moment ,until At that time, the first Each shooting moment .

[0014] Its further technical solution is, according to the first Each shooting moment Trigger camera to acquire the first Images of the film rewinding include: Calculate the first Triggering time When the first Triggering time Re-determine the first time step when it is less than the current time step. Each shooting moment Otherwise, adjust the exposure window to cover the first... Each shooting moment and in the Triggering time Trigger camera to acquire the first Images of the film being wound up, in which, It's a trigger delay.

[0015] The beneficial technical effects of this application are: This application discloses a visual inspection method for film winding quality, which determines the uniform distribution of film core circumferentially according to the required total number of shots. By identifying different circumferential positions of the roll core and combining them with winding attribute parameters, the shooting time at the corresponding circumferential position of the roll core can be calculated. This triggers the camera to capture an image of the membrane at the corresponding circumferential position of the roll core for visual inspection of membrane winding quality. This allows for uniform shooting during the winding process, avoiding the phenomenon of periodic overlap of shooting positions. Consequently, it is beneficial to evaluate the membrane winding quality at different circumferential positions, thereby improving the reliability and robustness of visual inspection of membrane winding quality. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the cross section of the film core where the camera shooting position is located in one embodiment of this application.

[0017] Figure 2 This is a flowchart of a visual inspection method for film winding quality according to one embodiment of this application.

[0018] Figure 3 This is a flowchart of a visual inspection method for film winding quality according to another embodiment of this application. Detailed Implementation

[0019] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0020] This application discloses a visual inspection method for film winding quality. This method is applied to a film winding quality visual inspection system. In this type of system, a winding motor drives a winding shaft to rotate the core, thereby winding the film onto the core. Please refer to [reference needed]. Figure 1 Camera 1 is positioned facing the roll core 2, with the roll core 2 located within the field of view of camera 1. To ensure stable shooting during the winding process, the optical axis of camera 1 is radially aligned with the cross-section of the cylindrical roll core 2. After fixing the relative positions of camera 1 and roll core 2, the camera shooting position of camera 1 on roll core 2 can be determined. This camera shooting position is the intersection of the optical axis of camera 1 and roll core 2. In practical applications, camera 1 can be a single-point camera, or it can include multiple cameras arranged sequentially along the axial direction of roll core 2, or a line scan camera with scanning points arranged sequentially along the axial direction of roll core 2. In this case, it actually includes multiple camera shooting positions arranged sequentially along the axial direction of roll core 2. The method of this application is also applicable. The visual inspection method for film winding quality of this application includes the following steps, please refer to... Figure 2 The flowchart shown: Step S1, Initialize the start time And determine the total number of shots. .

[0021] Step S2, determine the uniformly distributed circumferential distribution of the core along the core's cross-section at the camera's shooting position. The circumferential position of the core.

[0022] In order to accurately assess the quality of film winding, the core idea of ​​this application is to base it on the total number of shots. Shoot evenly, avoiding overlap between shooting positions, to ensure optimal results. Images from different circumferential positions are beneficial for improving the reliability and robustness of visual inspection of film winding quality. Based on this idea, this application first determines the image according to the principle of uniform imaging. Each core has an independent circumferential position. Based on the relative arrangement of camera 1 and core 2 in the film winding quality visual inspection system, during the winding process, the camera shooting position of camera 1 on core 2 is always located on a cross-section of the core, as shown in the image. Figure 2 As shown, this application divides the cross section of the core evenly along the circumferential direction into... This allows us to locate [the position / situation]. The angle between the lines connecting two adjacent circumferential positions of the core and the center O of the core cross-section. .

[0023] Introducing parameters Any point on the cross section of the roll core where the camera is positioned. The circumferential position of the core can be denoted as For ease of description and definition, this application first determines the camera position at time 0 on the cross-section of the roll core. Then, the camera position at time 0 was used for shooting. Begin by defining the circumferential position of the 0th core sequentially in a counter-clockwise direction. ~No. Circumferential position of each core Those skilled in the art will understand that a clockwise direction is also acceptable.

[0024] To facilitate locating the position of each circumferential position of the roll core on the roll core cross section, a basic phase angle is introduced for each circumferential position: on the roll core cross section where the camera shooting position is located, the center O of the roll core cross section is used as the reference point for the camera shooting position at time 0. The line connecting the two points is the baseline. For any given point... Circumferential position of each core Determine the center O of the circle at which the core cross section is rotated counterclockwise from the baseline. Circumferential position of each core The angle between the lines connecting them is denoted as the first angle. The basic phase angle of each core circumferential position is Therefore, it can be determined that the first The basic phase angle of each core circumferential position for:

[0025] in, It is the starting phase angle, and also the circumferential position of the 0th core. The basic phase angle. This angle can be customized, but usually the starting phase angle can be directly taken. The camera position at 0:00. Directly used as the circumferential position of the 0th core .

[0026] Step S3, initialization in During the film winding process, the winding attribute parameters are used to determine the time relative to the previous shooting moment. Reaching the minimum time interval After that, the first rotation to the 1st The moment when the circumferential position of the roll core reaches the camera's shooting position is taken as the first... Each shooting moment .

[0027] The previous shooting moment That is, the starting time. minimum time interval It's a customizable value. Based on this, it can be determined according to the first shooting time. The requirements are to reasonably initialize the start time. When the first shooting moment is required At that time, only the start time needs to be initialized. That's all. Set it according to your needs. For example, when you need the first shooting moment. At that time, initialize the start time. That's all.

[0028] Although the angle between the line connecting two adjacent circumferential positions of the core on the cross section and the center O of the core cross section. It is fixed, but as the winding process proceeds, more and more film is wound onto the core, and the thickness of the core and film increases, causing the rotation angle to change. The length of the film used for winding varies. Furthermore, in actual winding, after the previous shot is taken, the film is usually not immediately turned around the angle. This will satisfy the minimum time interval. The requirements are often met, and multiple turns of winding are often required, especially when the winding speed is high, such as the winding speed in actual applications, which may reach 120m / s.

[0029] In one embodiment, based on the first The basic phase angle of each core circumferential position Determine the first Each shooting moment includes the following steps, please refer to... Figure 3 The flowchart shown: (1) First, based on the roll-up attribute parameters and the first The basic phase angle of each core circumferential position Determine the first rotation to the th from time 0. The equivalent winding radius when the circumferential position of the roll core reaches the camera's shooting position. .

[0030] The winding attribute parameters used in this application include the core radius. membrane thickness winding speed Length of winding at time 0 In practice, the winding process usually doesn't start directly from the camera's shooting position at time 0. Instead, a section of film is pre-wound and fixed, such as... Figure 1 The shaded area represents the film that was wound up at time 0. With the film cores arranged counterclockwise, and the film being wound clockwise, the length of the film between the starting position of the winding on the film core and the camera's shooting position at time 0 is the length already wound at time 0. .

[0031] Using the core radius membrane thickness as well as The length of the coil at that time The equivalent winding radius at time 0 can be determined. :

[0032] The equivalent winding radius The calculation idea is: the membrane's torus has a rectangular structure, and the membrane thickness... The length of the wound is The cumulative toroidal area of ​​the wound film is then... .radius The cross-sectional area of ​​the core is Then add the cumulative annular area of ​​the wound film. This will allow you to obtain the core at a winding length of [length missing]. The total area behind the membrane is During the winding process, the radius of the outer film of the core increases spirally rather than changing uniformly. This application adopts the concept of equivalence, using a uniformly changing equivalent radius to represent it, which allows us to determine the equivalent winding radius of the equivalent cross-section reaching the total area. satisfy Therefore, the equivalent winding radius can be obtained. The calculation formula.

[0033] Then, based on the equivalent winding radius at time 0... Combined with the first The basic phase angle of each core circumferential position This allows us to determine the first rotation from time 0 to the [missing information]. The equivalent winding radius when the circumferential position of the roll core reaches the camera's shooting position. Please combine Figure 1 Starting from time 0, rotate the first... The basic phase angle corresponding to each circumferential position of the core Then you can rotate to the first position. The equivalent take-up radius can be calculated from the circumferential position of each core when it reaches the camera's shooting position. , is represented as:

[0034] The idea behind the above calculation formula is: for each rotation This allows the film to be completely rolled up, increasing the radius and thickness of the film. Therefore, the fundamental phase angle of rotation When, the corresponding radius increment is .

[0035] (2) Based on satisfying the minimum time interval Minimum time required The minimum time is determined by combining the winding attribute parameters. The target equivalent winding radius at time .

[0036] Similarly, it is necessary to use the equivalent take-up radius at time 0, calculated based on the take-up attribute parameters. Then, based on the equivalent winding radius at time 0... Combining the minimum time and winding speed Determine the target equivalent winding radius ,include: First, based on the winding speed Determine the time from time 0 to the minimum time. Total winding length When the winding speed When it is a constant value, And when the winding speed When it changes over time, the winding speed can be calculated. The curve changes with time from time 0 to the minimum time. The total winding length is obtained by measuring the area between the two points. .

[0037] Determine the time from 0 to the minimum time. Total winding length Then, the target equivalent winding radius can be calculated based on the principle of equal area. :

[0038] The calculation idea behind this formula is the same as the equivalent winding radius mentioned above. The same applies, so I will not repeat it here.

[0039] (3) Determine the first rotation from time 0 to the [missing value]. Complete the circumferential position of each core before finishing. The coil winding operation allows for winding from the equivalent winding radius. Increase to the first time the target equivalent winding radius is reached The moment as the first Each shooting moment The obtained integer parameters Specifically: First, calculate the equivalent winding radius. Increase to the target equivalent winding radius Required number of laps , including calculation Then calculate , This indicates rounding up to the nearest integer.

[0040] Then calculate the rotation from the first rotation starting at time 0 to the [missing value]. Complete the circumferential position of each core before finishing. Total winding length during winding :

[0041] This calculation formula is also based on the membrane ring area, starting from time 0 and rotating to the [missing information - likely a time period]. The equivalent winding radius at each circumferential position of the core is Based on this, the film thickness will increase as a result of winding the film one turn. The radius increment, therefore continue to complete After the winding operation, the radius increases. Therefore, starting from time 0, the first rotation continues until the [missing value]. Complete the circumferential position of each core before finishing. The equivalent radius after the coil winding operation is The area of ​​the equivalent circle is The equivalent winding radius at time 0. The area of ​​the equivalent circle below is Therefore, the area increment generated from time 0 is Since this area is generated by the film winding, the total winding length can be determined. .

[0042] Then combine the winding speed It can be determined that the total winding length has been reached. The time taken to obtain the first Each shooting moment When the winding speed When it is a constant value, And when the winding speed When it changes over time, it depends on the winding speed. The curve that changes over time can also be used to infer the first... Each shooting moment .

[0043] In addition, When the value is close to an integer, a threshold is used to account for floating-point errors. To determine: when Time to determine Otherwise, determine according to the above formula. The threshold here You can customize the value, for example, the typical value is Therefore, the number of full laps can be calculated. After that, it is also necessary to base the calculated number of laps on... Perform cyclic verification to determine the first Each shooting moment This includes: when based on the currently determined number of laps The calculation of the first Each shooting moment season And based on the updated number of laps Recalculate the first Each shooting moment ,until At that time, the first Each shooting moment This ensures robustness.

[0044] In addition, in practical applications, the number of full revolutions is given. To set a maximum value and avoid infinite loops, you could set it to something like this: Furthermore, in actual implementation, due to the thickness of the membrane... The smallest values ​​are typically in the µm range, so double is needed for calculations to avoid using float.

[0045] Step S4, according to the first Each shooting moment Trigger camera to acquire the first Images of the film rewinding process and visual inspection of the film rewinding quality, including: Calculate the first Triggering time When the first Triggering time Re-determine the first time step when it is less than the current time step. Each shooting moment Otherwise, adjust the exposure window to cover the first... Each shooting moment and in the Triggering time Trigger camera to acquire the first Image of the film being wound up. Among them, This is the trigger delay. Additionally, if milliseconds or higher precision are required, the system's high-precision clock and lead time can be fine-tuned, taking into account trigger link jitter.

[0046] In practical applications, a shooting time window can also be set. Each shooting moment An error will be reported if the shooting time window is exceeded.

[0047] Additionally, the actual trigger time and the captured angle can be recorded for later error analysis. If the error occurs due to network latency, device latency, or other reasons, it can be used to prevent such errors from occurring. Triggering time If shooting is triggered, return to the repositioning point. Each shooting moment .

[0048] Step S5, let And repeat steps S3 and S4 to determine the first step again. Each shooting moment is recorded and filming continues until... .

[0049] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A visual inspection method for film winding quality, characterized in that, The visual inspection method for film winding quality includes: Initialization start time And determine the total number of shots. ; Determine that the components are evenly distributed along the circumference of the roll core on the cross section of the roll core where the camera is positioned. The circumferential position of each core; Initialization parameters During the winding process, the timing relative to the previous shooting time is determined based on the winding attribute parameters. Reaching the minimum time interval After that, the first rotation to the 1st The moment when the circumferential position of the roll core reaches the camera's shooting position is taken as the first... Each shooting moment , The previous shooting moment The starting time ; According to the Each shooting moment Trigger camera to acquire the first The film winding image is captured and visual inspection of the film winding quality is performed. And reaffirm the first The shooting moment until ; The visual inspection method for film winding quality further includes: on the cross-section of the roll core where the camera shooting position is located, using the line connecting the center of the cross-section of the roll core and the camera shooting position at time 0 as a reference line, determining the distance from the reference line to the center of the cross-section of the roll core and the position at time 0 by rotating counterclockwise around the reference line. The included angle between the lines connecting the circumferential positions of each core is obtained. The basic phase angle of each core circumferential position According to the roll-up attribute parameters and the first The basic phase angle of each core circumferential position Determine the first rotation to the th from time 0. The equivalent winding radius when the circumferential position of the roll core reaches the camera's shooting position. Based on satisfying the minimum time interval Minimum time required The minimum time is determined by combining the winding attribute parameters. The target equivalent winding radius at time ; Determine the first rotation from time 0 to the th Complete the circumferential position of each core before finishing. The coil winding operation allows for winding from the equivalent winding radius. Increase to the first time the target equivalent winding radius is reached The moment as the first Each shooting moment Integer parameters ;in, It is the initial phase angle; The winding attribute parameters should include at least the core radius. membrane thickness winding speed Length of winding at time 0 Determine the equivalent winding radius Equivalent winding radius to target Includes: based on core radius membrane thickness as well as The length of the coil at that time Determine the equivalent winding radius at time 0. Based on the equivalent winding radius at time 0 Combined with the first The basic phase angle of each core circumferential position Determine the equivalent winding radius According to the winding speed Determine the time from time 0 to the minimum time. Total winding length And determine the target equivalent winding radius. .

2. The visual inspection method for film winding quality according to claim 1, characterized in that, Determine the first Each shooting moment include: Calculate from equivalent winding radius Increase to the target equivalent winding radius Required number of laps And calculate the first rotation from time 0 to the [missing value]. Complete the circumferential position of each core before finishing. Total winding length during winding Combined with winding speed Determine the total winding length has been reached. The time taken to obtain the first Each shooting moment .

3. The visual inspection method for film winding quality according to claim 2, characterized in that, Determine the first Each shooting moment include: calculate ; when Time to determine Otherwise confirm , Indicates rounding up. It is a threshold; Based on the calculated number of laps Perform cyclic verification to determine the first Each shooting moment .

4. The visual inspection method for film winding quality according to claim 3, characterized in that, Based on the calculated number of laps Perform cyclic verification to determine the first Each shooting moment include: When based on the currently determined number of laps The calculation of the first Each shooting moment season And based on the updated number of laps Recalculate the first Each shooting moment ,until At that time, the first Each shooting moment .

5. The visual inspection method for film winding quality according to claim 1, characterized in that, According to the Each shooting moment Trigger camera to acquire the first Images of the film rewinding include: Calculate the first Triggering time When the first Triggering time Re-determine the first time when it is less than the current time. Each shooting moment Otherwise, adjust the exposure window to cover the first... Each shooting moment and in the Triggering time Trigger camera to acquire the first Images of the film being wound up, in which, It's a trigger delay.

Images