Production equipment and production method of high-light-transmittance PVC film

Abstract

The present application provides a production device and a production method for a high-transmittance PVC film, which belongs to the technical field of PVC film production. The production equipment includes a filtering device, which includes a bracket, a box, a filter cartridge and a driving mechanism. The box is fixed on the bracket, and the filter cartridge is rotatably arranged in the box. The driving mechanism is connected to the filter cartridge, and the box is provided with a liquid inlet and a liquid outlet. A fixed plate is provided at one end of the filter cartridge, and an opening is provided at the other end. An arc-shaped partition is provided at the end of the box with the liquid inlet facing the fixed plate. Several filtering areas are provided on the filter cartridge along its circumference, and the mesh size of the filter screen in each filtering area is different. In the present invention, by rotating the filter cartridge, different filtering areas and the liquid outlet are aligned, which can achieve a gradual improvement in the filtering effect, thereby filtering out impurities and particles in the plasticized plastic to the greatest extent, reducing the generation of crystal points, and improving the appearance quality of the PVC film.

Description

Technical Field

[0001] The present invention relates to the technical field of PVC film production, and in particular to a production device and a production method for a high-light-transmittance PVC film. Background Art

[0002] PVC film, or Polyvinylchlorid film, is primarily composed of polyvinyl chloride (PVC), with other ingredients added to enhance its heat resistance, toughness, and ductility. It is a popular and widely used synthetic material worldwide. PVC film ranks second in global usage among various synthetic materials. PVC is the most suitable material for producing three-dimensional surface films.

[0003] The production equipment for PVC film is a highly integrated system, mainly including core components such as plastic extruders, cooling and shaping tables, traction devices and film winding machines. The appearance quality of films produced by traditional PVC film equipment is poor, especially the easy formation of crystal points. The cause of this problem is the presence of particles in the plasticized plastic liquid. The cause of these particles may be insufficient processing temperature, insufficient plasticization, foreign matter impurities accidentally dropped into the plasticizer, or insufficient shear force of the internal mixer / extruder, which cannot effectively break up the resin particles. Therefore, the simplest and most effective way is to filter the plasticized plastic liquid. However, traditional filtering devices only have a fixed mesh filter, and such equipment generally cannot be shut down to replace the filter. This results in insufficient filtration of the plastic liquid, which ultimately affects the appearance quality of the PVC film. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a production device and a production method for a high-light-transmittance PVC film.

[0005] The technical solution adopted by the present invention is as follows: In the first aspect, the present application provides a production equipment for high-transmittance PVC film, including a mixer, an internal mixer, a filtering device, a discharging device, a calender, a cooling device, a slitting machine, a winder and a control system, and also includes a visual inspection device for detecting the appearance of the film, the filtering device includes a bracket, a box, a filter cartridge and a driving mechanism, the box is fixed on the bracket, the filter cartridge is rotatably arranged in the box, the driving mechanism is arranged on the bracket and includes a drive shaft extending into the box and connected to the filter cartridge, the end surface of the box away from the driving mechanism is provided with a liquid inlet, and the lower part of its circumferential side wall is provided with a liquid outlet, the filter cartridge is provided with a fixed plate at one end close to the driving mechanism and connected to the drive shaft, and an opening is provided at the other end, the end of the box provided with the liquid inlet is provided with an arc-shaped partition facing the fixed plate, and the filter cartridge is provided with a plurality of filtering areas along its circumference, and the mesh size of the filter screen of each filtering area is different. During filtration, the filter cartridge is driven to rotate by the driving mechanism so that different filtering areas are aligned with the liquid outlet.

[0006] In some embodiments, a cleaning port is provided on the filter cartridge, the cleaning port is provided through the filter cartridge, the liquid outlet is provided with a reversing valve, one outlet of the reversing valve is connected to the discharge device, and the other outlet is connected to the cleaning frame, a plurality of flushing nozzles are provided on the top of the box body facing the filter cartridge, and the liquid inlet is provided with an on-off control valve.

[0007] In some embodiments, the reversing valve includes a valve body, a valve plate, a rocker arm and a driving cylinder. The valve body includes a first connection port, a second connection port and a third connection port. The first connection port is connected to the liquid outlet. The valve plate is rotatably arranged at the intersection of the three connection ports through a bearing seat. The driving cylinder is arranged on the outer wall of the valve body. One end of the rocker arm is connected to the valve plate, and the other end is connected to the driving cylinder. The second connection port is connected to the discharge device, and the third connection port is connected to the cleaning frame. Under the drive of the driving cylinder, the reversing valve has a working state in which the first connection port and the second connection port are connected and a cleaning state in which the first connection port and the third connection port are connected.

[0008] In some embodiments, the liquid outlet pipe of the internal mixer directly extends into the filtration area near the liquid inlet and the liquid outlet.

[0009] In some embodiments, a heating device is provided on the lower end surface of the arc-shaped partition.

[0010] In some embodiments, a pressure sensor is provided on the pipeline between the internal mixer and the filtering device near the inlet end of the filtering device.

[0011] In some embodiments, the mixer includes a main barrel and several auxiliary barrels, a quantitative control valve is provided on the auxiliary barrel and between the main barrel, and lubricant is stored in one of the auxiliary barrels.

[0012] In a second aspect, the present application further provides a production method for the production equipment of the high-light-transmittance PVC film, comprising the following steps:

[0013] S1: Put the raw materials into the mixer according to the required proportion and mix them;

[0014] S2: The mixed raw materials are heated and plasticized in an internal mixer;

[0015] S3: The plasticized raw material is filtered through a filtering device;

[0016] S4: The filtered raw material is initially formed into sheets through the discharging device;

[0017] S5: The sheet is calendered into a film of desired thickness through a calender, and the film is cooled;

[0018] S6: Use a visual inspection device to detect whether there are crystal points on the film; if the crystal points on the film do not meet the standards, the drive mechanism drives the filter cartridge to rotate so that the filter area with a larger filter mesh number is aligned with the liquid outlet for filtration; if the crystal points on the film meet the standards, the liquid is transported to the downstream;

[0019] S7: The film is cut into the required width by the slitting machine;

[0020] S8: The cut film is wound up by a winder.

[0021] In some embodiments, step S6 includes the following steps:

[0022] S61: Continuous image acquisition of the moving film surface using a line array camera in conjunction with a coaxial cold light source;

[0023] S62: Preprocessing the collected raw image data, including background noise removal based on dark field correction and multi-exposure HDR image fusion processing;

[0024] S63: Using an adaptive threshold segmentation algorithm to extract suspected crystal point regions, and calculating the contour area A, aspect ratio R, and surface grayscale gradient G of each region;

[0025] S64: The morphological parameters (A, R, G) of the suspected crystal point area are input into the pre-trained lightweight convolutional neural network for classification to distinguish between real crystal points, bubbles, dust artifacts and foreign matter;

[0026] S65: Counting the number N of crystal points per unit area based on the classification result, and combining the distribution of crystal point diameters D, outputting a film quality grade signal based on a preset judgment threshold;

[0027] S66: Based on the film quality grade signal, select to replace the filter area with a larger filter mesh, and / or add a certain amount of lubricant into the main barrel through the quantitative control valve.

[0028] In some embodiments, a method for controlling a filter device is also included, comprising the following steps:

[0029] S31: When the equipment is initially running, the filter area with the smallest filter mesh size is aligned with the liquid outlet;

[0030] S32: rotating the filter cartridge so that the filter area with a larger filter mesh size is aligned with the liquid outlet according to the inspection result of the visual inspection device, and repeating this step based on the inspection result of the visual inspection device;

[0031] S33: When the pressure sensor detection value exceeds the threshold, the on-off control valve is closed, the screw speed in the internal mixer is reduced, and the reversing valve is switched to the cleaning state. Then, the filter cartridge is rotated back and forth with the cleaning port facing downward, so that the flushing nozzle flushes each filter area.

[0032] S34: After the flushing is completed, the filter area with the smallest filter mesh number is aligned with the liquid outlet, or the filter area used before the flushing is realigned with the liquid outlet, and then the heating device is started to heat the filter area.

[0033] The beneficial effects of the present invention are as follows: in the present invention, by rotating the filter cartridge, different filter areas and liquid outlets are aligned, which can achieve a gradual improvement in the filtering effect, thereby filtering out impurities and particles in the plasticized plastic to the greatest extent, reducing the generation of crystal points, and improving the appearance quality of the PVC film. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0035] Figure 1 This is a schematic diagram of a production device for a high-light-transmittance PVC film according to the present invention;

[0036] Figure 2 Schematic diagram of the filtering device in the present invention Figure 1 ;

[0037] Figure 3 Schematic diagram of the filtering device in the present invention Figure 2 ;

[0038] Figure 4is a cross-sectional view of the filter device of the present invention;

[0039] Figure 5 A partial cross-sectional view of the filter device of the present invention;

[0040] Figure 6 This is a schematic diagram of the filtering device of the present invention without the housing;

[0041] Figure 7 is a flow chart of the production method of the present invention;

[0042] Figure 8 This is a flow chart of the film inspection method using a visual inspection device according to the present invention;

[0043] Figure 9 This is a flow chart of the filter device control method of the present invention.

[0044] In the figure, 1-mixer, 2-internal mixer, 3-filtering device, 30-bracket, 31-box, 32-filter cartridge, 320-fixed plate, 321-opening, 322-filtering area, 323-cleaning port, 33-driving mechanism, 34-liquid inlet, 35-liquid outlet, 36-arc partition, 4-discharging device, 5-calender, 6-slitting machine, 7-winding machine, 8-reversing valve, 80-valve body, 81-valve plate, 82-rocker, 83-driving cylinder, 84-first connecting port, 85-second connecting port, 86-third connecting port. DETAILED DESCRIPTION

[0045] The following description provides specific application scenarios and requirements for this specification, with the goal of enabling those skilled in the art to make and use the contents of this specification. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but is intended to be accorded the broadest scope consistent with the claims.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "longitudinal", "transverse", "radial", "length", "width", "thickness", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe this application and its embodiments, and are not intended to limit the indicated devices, elements or components to a specific orientation, or to be constructed and operated in a specific orientation.

[0047] Secondly, the terms "first", "second" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different components and should not be understood as limitations on the embodiments of the present application.

[0048] Furthermore, the terms "installed," "disposed," "provided with," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral structures; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; or internal communication between two devices, elements, or components.

[0049] For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] The flowcharts used in this application illustrate operations implemented by systems according to some embodiments of this specification. It should be clearly understood that the operations of the flowcharts may not be implemented in sequence. Rather, the operations may be implemented in reverse order or simultaneously. In addition, one or more additional operations may be added to the flowcharts. One or more operations may be removed from the flowcharts.

[0051] Regarding the drawings of this application, it should be clearly understood that the drawings are for illustration and description purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not necessarily drawn to scale.

[0052] like Figures 1 to 6 As shown, this specification provides a production equipment for high-transmittance PVC film, including a mixer 1, an internal mixer 2, a filtering device 3, a discharging device 4, a calender 5, a cooling device, a slitting machine 6, a visual inspection device, a thickness gauge, a winder 7 and a control system.

[0053] The mixer 1 is used to mix raw materials in a required proportion. It includes a main barrel and several auxiliary barrels. The raw materials are stirred and mixed at a high speed in the main barrel according to the required proportion. A quantitative control valve is provided between the auxiliary barrel and the main barrel. A lubricant is stored in one of the auxiliary barrels.

[0054] The internal mixer 2 is used to heat and plasticize the mixed raw materials;

[0055] The filtering device 3 is used to filter the plasticized raw material; specifically, the filtering device 3 includes a bracket 30 , a box 31 , a filter cartridge 32 and a driving mechanism 33 .

[0056] The box body 31 is fixed on the bracket 30, the filter cartridge 32 is rotatably arranged in the box body 31, and the driving mechanism 33 is arranged on the bracket 30 and includes a driving shaft extending into the box body 31 and connected to the filter cartridge 32.

[0057] The end surface of the box body 31 away from the driving mechanism 33 is provided with a liquid inlet 34 , and the lower part of the circumferential side wall thereof is provided with a liquid outlet 35 .

[0058] The filter cartridge 32 is provided with a fixed plate 320 at one end close to the driving mechanism 33 and is connected to the driving shaft, and an opening 321 is provided at the other end. The box body 31 is provided with a liquid inlet 34 at one end thereof and an arc-shaped partition 36 is provided toward the fixed plate 320. Preferably, the arc-shaped partition 36 is a semicircular plate with a diameter smaller than that of the filter cartridge 32, and the arc-shaped partition 36 is located at the upper part of the opening 321.

[0059] The filter cartridge 32 is circumferentially provided with a plurality of filter areas 322 and a cleaning port 323. The filter screens in each filter area 322 have different mesh sizes. The cleaning port 323 extends through the filter cartridge 32. Specifically, the mesh sizes of the filter screens in the filter areas 322 gradually decrease or increase from one side of the cleaning port 323 to the other. The mesh size of the filter screen can also be understood as the mesh size of the filter screen. Generally, a larger mesh size indicates a better filtration effect.

[0060] Of course, the mesh size of the filter screens on both sides of the cleaning port 323 may gradually increase or decrease, so as to form a symmetrical body.

[0061] In addition, if the mesh size of the filter screen in each of the filter areas 322 is the same, the function of online filter screen replacement can also be achieved.

[0062] During filtration, the filter cartridge 32 is driven to rotate by the driving mechanism 33 so that different filtration areas 322 and the liquid outlet 35 are aligned, thereby obtaining different filtration effects.

[0063] Furthermore, the liquid outlet 35 is provided with a reversing valve 8, and the reversing valve 8 includes a valve body 80, a valve plate 81, a rocker rod 82 and a driving cylinder 83. The valve body 80 includes a first connecting port 84, a second connecting port 85 and a third connecting port 86. The first connecting port 84 is connected to the liquid outlet 35, and the valve plate 81 is rotatably arranged at the intersection of the three connecting ports through a bearing seat. The driving cylinder 83 is arranged on the outer wall of the valve body 80, one end of the rocker rod 82 is connected to the valve plate 81, and the other end is connected to the driving cylinder 83, the second connecting port 85 is connected to the discharging device 4, and the third connecting port 86 is connected to a cleaning frame, which is used to store cleaning waste liquid. Under the drive of the driving cylinder 83, the reversing valve 8 has a working state in which the first connecting port 84 and the second connecting port 85 are connected and a cleaning state in which the first connecting port 84 and the third connecting port 86 are connected.

[0064] A plurality of flushing nozzles are provided on the top of the box body 31 toward the filter cartridge 32 , and an on-off control valve is provided on the liquid inlet 34 .

[0065] When it is necessary to flush the filter cartridge 32, close the on-off control valve, reduce the speed of the screw in the internal mixer 2, switch the reversing valve 8 to the cleaning state, and then always keep the cleaning port 323 facing downward and rotate the filter cartridge 32 back and forth so that the flushing nozzle flushes each filter area 322, so that the particles on the filter cartridge 32 can basically fall from the cleaning port 323, thereby achieving fast and efficient online cleaning.

[0066] Furthermore, the liquid outlet pipe of the internal mixer 2 can be directly extended into the filtration area 322 near the liquid inlet 34 and the liquid outlet 35, and can be as close as possible without affecting the rotation of the filter cylinder 32, thereby reducing the temperature loss of the raw material after plasticization to ensure its fluidity.

[0067] Furthermore, a heating device is provided on the lower end surface of the arc-shaped partition 36 to quickly increase the temperature of the filter area 322 at the liquid outlet 35 and prevent it from being flushed by the flushing nozzle. The heating device includes a plurality of heating tubes provided on the lower end surface of the arc-shaped partition 36 and a heating source provided on the bracket 30.

[0068] A pressure sensor is provided on the pipeline between the internal mixer 2 and the filtering device 3 near the inlet end of the filtering device 3 .

[0069] The discharging device 4 is used to preliminarily shape the filtered raw materials into sheets, which is equivalent to an extruder. The calender 5 is used to calender the sheets into films of a desired thickness.

[0070] The visual inspection device is used to inspect the appearance of the film, with a focus on inspecting whether there are crystal points on the film.

[0071] The thickness gauge is used to detect the thickness of the film.

[0072] The cooling device is used to cool the qualified film; specifically, the cooling device can be independent, that is, a separate cooling roller is set to convey the film, or it can be combined with the calender 5, that is, the pressure roller in the calender 5 is set with a cooling function, which can be achieved only by circulating the cooling medium.

[0073] The slitting machine 6 is used to cut the cooled film into desired widths.

[0074] The winder 7 is used to wind up the cut film.

[0075] It should be understood that the mixer 1 , the internal mixer 2 , the discharging device 4 , the calender 5 , the cooling device, the slitting machine 6 , the thickness gauge and the winder 7 may refer to commonly used equipment in the technical field.

[0076] like Figures 7 to 9 As shown, this specification provides a production method based on the above production equipment, including the following steps:

[0077] S1: Put the raw materials into mixer 1 according to the required proportion and mix them;

[0078] S2: The mixed raw materials are heated and plasticized in an internal mixer 2;

[0079] S3: The plasticized raw material is filtered through the filtering device 3;

[0080] S4: The filtered raw material is initially formed into a sheet through the discharging device 4;

[0081] S5: The sheet is calendered into a film of desired thickness by a calender 5; wherein the film is cooled simultaneously during calendering;

[0082] S6: The film is inspected for crystal spots by a visual inspection device. If the crystal spots on the film do not meet the standards, the filter cartridge 32 is driven by the drive mechanism 33 to rotate so that the filter area 322 with a larger filter mesh size is aligned with the liquid outlet 35 for filtration. If the crystal spots on the film meet the standards, the liquid is transported downstream.

[0083] S7: The film is cut into the required width by the slitting machine 6;

[0084] S8: The cut film is wound up by the winder 7.

[0085] In step S6, the method for detecting whether there are crystal points on the film by the visual inspection device includes the following steps:

[0086] S61: A line scan camera, coupled with a coaxial cold light source, continuously captures images of the moving film surface. The continuous motion of film production lines (often reaching speeds of 200-500 m / min) requires the imaging system to possess high-speed acquisition capabilities. Line scan cameras achieve infinite imaging through progressive scanning, avoiding the image stitching errors common with area scan cameras.

[0087] Secondly, the coaxial cold light source is blue light with a wavelength of 450±10nm, which forms a uniform illumination field in conjunction with the diffuse reflection plate, and can cause the crystal point to produce a significant sudden change in light intensity.

[0088] S62: Preprocessing the collected raw image data, including background noise removal based on dark field correction and multi-exposure HDR image fusion processing;

[0089] Since the film is reflective or translucent, dark field correction is performed to eliminate the noise of the camera and light source itself, such as dust or lens stains, to ensure the accuracy of subsequent analysis.

[0090] HDR fusion processes images with different exposure times to capture details in highlights and shadows, avoiding overexposure or underexposure that may cause missed detection of crystal points. Multi-exposure HDR image fusion processing includes:

[0091] Three frames of images with different exposure times are continuously collected at the same film position, and the exposure times are 0.5ms, 1ms, and 2ms respectively; through the weight function Perform pixel-level fusion, where is the pixel intensity, is the local area mean, is the standard deviation.

[0092] This approach resolves the dynamic range contradiction in transparent film imaging: short exposures preserve highlight details (such as crystal edges), while long exposures capture dark structures. Weighted fusion is then used to expand the effective grayscale level.

[0093] S63: Using an adaptive threshold segmentation algorithm to extract suspected crystal point regions, and calculating the contour area A, aspect ratio R, and surface grayscale gradient G of each region; wherein the threshold calculation formula of the adaptive threshold segmentation algorithm is:

[0094] ;

[0095] in, In pixels The grayscale mean of the 15×15 neighborhood centered on the image reflects the gradient characteristics of the film background, such as the transmittance change caused by uneven thickness. The 15×15 window corresponds to a physical size of 0.45 mm, matching the minimum spacing between crystal points.

[0096] is the standard deviation of the corresponding neighborhood, Threshold: Based on the normal distribution assumption, it increases the detection probability of crystal point pixels.

[0097] This method uses the local mean plus three times the standard deviation as the threshold, dynamically adjusting the threshold based on brightness variations in different image regions. This method is more flexible than a global threshold and helps distinguish crystals from the background, especially in conditions of uneven lighting. Extracting morphological parameters (area, aspect ratio, and grayscale gradient) can help distinguish crystals from other similar defects. For example, bubbles may be more round (with an aspect ratio close to 1), while dust has a different texture.

[0098] S64: The morphological parameters of the suspected crystal point area The input is classified into a pre-trained lightweight convolutional neural network, such as MobileNetV3, to distinguish between real crystal points, bubbles, dust artifacts, and foreign objects. The area, aspect ratio, and grayscale gradient are normalized to form three-channel input data, which reduces a lot of calculations compared to the original RGB image.

[0099] S65: Count the number of crystal points N per unit area according to the classification results, and combine the distribution of crystal point diameter D with the preset judgment threshold. Output film quality grade signal.

[0100] S66: Based on the film quality grade signal, a filter area 322 with a larger filter mesh size is selected for filtration and / or a certain amount of lubricant is added into the main barrel through a quantitative control valve.

[0101] For example, the decision threshold is set as:

[0102] When there is any crystal point diameter When , trigger the level Ⅰ signal;

[0103] when And when the number of crystal points per unit area N>5 / m², the level II signal is triggered.

[0104] In step S65, if the level I signal is triggered, the filter cartridge 32 is driven to rotate by the driving mechanism 33 so that the filter area 322 with better filtering ability is aligned with the liquid outlet 35 for filtering; when the filter mesh number is increased by 30-40 meshes, the speed of the screw in the internal mixer 2 needs to be reduced by 5-8% to maintain the melt pressure.

[0105] If the level I signal continues to appear, the filter area 322 with a larger filter mesh number is aligned with the liquid outlet 35.

[0106] If the level II signal is triggered, a certain amount of lubricant is added into the main barrel through the quantitative control valve.

[0107] If the Level I signal and Level II signal are triggered at the same time, both will intervene at the same time.

[0108] In step S64, if foreign matter is detected on the film and the number of crystal points per unit area N is greater than 5 / m², a level I signal is triggered, and the filter cartridge 32 is driven to rotate by the driving mechanism 33 so that the filter area 322 with better filtering ability is aligned with the liquid outlet 35 for filtering.

[0109] The control method of the filter device 3 in this production method includes the following steps:

[0110] S31: During the initial operation of the device, the filter area 322 with the smallest filter mesh number is aligned with the liquid outlet 35; wherein, the filter area 322 with the smallest filter mesh number needs to be set based on the principle.

[0111] S32: According to the detection result of the visual detection device in step S6, if the level I signal is triggered, the filter cartridge 32 is rotated so that the filter area 322 with a larger filter mesh size is aligned with the liquid outlet 35, and this step is repeated based on the detection result of the visual detection device.

[0112] S33: When the detection value of the pressure sensor exceeds the threshold, the on-off control valve is closed, and the speed of the screw in the internal mixer 2 is reduced at the same time, and the reversing valve 8 is switched to the cleaning state. Then, the filter cartridge 32 is rotated back and forth with the cleaning port 323 always facing downward, so that the flushing nozzle flushes each filter area 322, so that the particles on the filter cartridge 32 can basically fall from the cleaning port 323, thereby achieving fast and efficient online cleaning.

[0113] S34: After the flushing is completed, the filter area 322 with the smallest filter mesh number is aligned with the liquid outlet 35 or the filter area 322 used before flushing is realigned with the liquid outlet 35, and then the heating device is started to heat the filter area 322 to avoid the temperature of the filter area 322 from decreasing after flushing, causing the plasticized plastic liquid to solidify during filtration.

[0114] It can be understood that the flushing medium and medium temperature should be controlled during flushing, and factors such as cost and flushing capacity should be comprehensively considered. For example, when water is used as the flushing medium, it is best to use high-temperature water. To save costs, boiling water at standard atmospheric pressure can be used, or high-pressure and high-temperature steam can be used for flushing, so that the medium temperature can be close to the plasticizing temperature.

[0115] In summary, after reading this detailed disclosure, those skilled in the art will appreciate that the foregoing detailed disclosure may be presented by way of example only and may not be limiting. Although not expressly stated herein, those skilled in the art will understand that the present application requires various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are intended to be proposed by the present application and are within the spirit and scope of the exemplary embodiments of the present application.

[0116] Furthermore, it should be understood that in the foregoing descriptions of the embodiments of this application, in order to facilitate understanding of a feature and to simplify this application, this application combines various features into a single embodiment, figure, or description thereof. However, this does not mean that the combination of these features is required. When reading this application, it is entirely possible for a person skilled in the art to label some of the devices as separate embodiments. In other words, the embodiments of this application can also be understood as the integration of multiple sub-embodiments. This also applies when the content of each sub-embodiment is less than all the features of a single aforementioned disclosed embodiment.

[0117] Finally, it should be understood that the embodiments of the application disclosed herein are illustrations of the principles of the embodiments of the present application. Other modified embodiments are also within the scope of the present application. Therefore, the embodiments disclosed in the present application are merely examples and not limitations. Those skilled in the art can adopt alternative configurations based on the embodiments in the present application to implement the applications in the present application. Therefore, the embodiments of the present application are not limited to the embodiments precisely described in the application.

Claims

1. A method for producing a highly light-transmitting PVC film production device, characterized in that: The invention relates to a production equipment for high-transmittance PVC film, the production equipment comprising a mixer, an internal mixer, a filtering device, a discharging device, a calender, a cooling device, a slitting machine, a winder and a control system, and also comprising a visual inspection device for detecting the appearance of the film, the filtering device comprising a bracket, a box, a filter cartridge and a driving mechanism, the box being fixed on the bracket, the filter cartridge being rotatably arranged in the box, the driving mechanism being arranged on the bracket and comprising a driving shaft extending into the box and connected to the filter cartridge, the end surface of the box away from the driving mechanism being provided with a liquid inlet, the lower part of the circumferential side wall of the box being provided with a liquid outlet, the filter cartridge being provided with a fixing plate at one end close to the driving mechanism and connected to the driving shaft, and an opening at the other end, an arc-shaped partition being provided at one end of the box provided with the liquid inlet facing the fixing plate, the filter cartridge being provided with a plurality of filtering areas along its circumference, the mesh size of the filter screen of each filtering area being different, and the filter cartridge being driven to rotate by the driving mechanism during filtration so that different filtering areas are aligned with the liquid outlet; The production method comprises the following steps: S1: putting the raw materials into a mixer according to the required proportions for mixing; S2: The mixed raw materials are heated and plasticized by an internal mixer; S3: The plasticized raw materials are filtered by a filtering device; S4: The filtered raw materials are preliminarily formed into sheets by a discharging device; S5: The sheets are calendered into films of the required thickness by a calender, and the films are cooled; S6: Whether there are crystal points on the film is detected by a visual inspection device; If the crystal points on the film do not meet the standards, the filter cylinder is driven to rotate by a driving mechanism so that the filter area with a larger filter mesh number is aligned with the liquid outlet for filtering; If the crystal points on the film meet the standards, it is transported to the downstream; In step S6, the following steps are included: S61: Continuous image acquisition of the moving film surface is performed by a linear array camera in combination with a coaxial cold light source; S62: Preprocessing the acquired raw image data, including background noise elimination based on dark field correction and multi-exposure HDR image fusion processing; S63: Using an adaptive threshold segmentation algorithm to extract suspected crystal point regions, and calculating the contour area A, aspect ratio R, and surface grayscale gradient G of each region; S64: The morphological parameters of the suspected crystal point area Input the pre-trained lightweight convolutional neural network for classification to distinguish between real crystal points, bubbles and dust artifacts; S S65: Count the number of crystal points N per unit area based on the classification results, and combine the distribution of the crystal point diameter D to output a film quality grade signal based on a preset judgment threshold; S66: Based on the film quality grade signal, select a filter area with a larger filter mesh size and / or add a certain amount of lubricant to the main barrel through the quantitative control valve; S7: The film is cut into the required width by the slitting machine; S8: The cut film is wound up by a winder.

2. The method for producing a highly light-transmittance PVC film according to claim 1, wherein: In the production equipment: a cleaning port is provided on the filter cartridge, the cleaning port is provided through the filter cartridge, a reversing valve is provided at the liquid outlet, one outlet of the reversing valve is connected to the discharge device, and the other outlet is connected to the cleaning frame, a plurality of flushing nozzles are provided at the top of the box body facing the filter cartridge, and an on-off control valve is provided at the liquid inlet.

3. The method for producing a highly light-transmittance PVC film according to claim 2, wherein: In the production equipment: the reversing valve includes a valve body, a valve plate, a rocker arm and a driving cylinder, the valve body includes a first connecting port, a second connecting port and a third connecting port, the first connecting port is connected to the liquid outlet, the valve plate is rotatably arranged at the intersection of the three connecting ports through a bearing seat, the driving cylinder is arranged on the outer wall of the valve body, one end of the rocker arm is connected to the valve plate, and the other end is connected to the driving cylinder, the second connecting port is connected to the discharging device, and the third connecting port is connected to the cleaning frame. Under the drive of the driving cylinder, the reversing valve has a working state in which the first connecting port and the second connecting port are connected and a cleaning state in which the first connecting port and the third connecting port are connected.

4. The method for producing a highly light-transmittance PVC film according to claim 2, wherein: In the production equipment: the liquid outlet pipe of the internal mixer directly extends into the filtering area near the liquid inlet and the liquid outlet.

5. The method for producing a highly light-transmittance PVC film according to claim 2, wherein: In the production equipment: a heating device is provided on the lower end surface of the arc-shaped partition.

6. The method for producing a highly light-transmittance PVC film according to claim 2, wherein: In the production equipment: a pressure sensor is provided on the pipeline between the internal mixer and the filtering device, close to the inlet end of the filtering device.

7. The method for producing a highly light-transmittance PVC film according to claim 2, wherein: In the production equipment: the mixer includes a main barrel and several auxiliary barrels, quantitative control valves are provided on the auxiliary barrels and between the main barrels, and lubricant is stored in one of the auxiliary barrels.

8. The method for producing a highly light-transmittance PVC film according to claim 1, wherein: It also includes a control method for the filtering device, including the following steps: S31: when the equipment is initially put into operation, the filter area with the smallest filter mesh number is first aligned with the liquid outlet; S32: according to the detection result of the visual detection device, the filter cartridge is rotated so that the filter area with a larger filter mesh number is aligned with the liquid outlet, and this step is repeated based on the detection result of the visual detection device; S33: when the detection value of the pressure sensor exceeds the threshold, the on-off control valve is closed, and the speed of the screw in the internal mixer is reduced, and the reversing valve is switched to the cleaning state, and then the filter cartridge is rotated back and forth with the cleaning port always kept facing down, so that the flushing nozzle flushes each filter area; S34: after the flushing is completed, the filter area with the smallest filter mesh number is aligned with the liquid outlet or the filter area used before flushing is realigned with the liquid outlet, and then the heating device is started to heat the filter area.

Images