On-line laser detection of coating thickness on coated paper

Abstract

The application discloses a device and method for on-line laser detection of coating thickness of a coated paper, and relates to the technical field of detection of coated paper production. The device comprises a detection assembly, laser probes are arranged at equal intervals on the circumferential side of a roller, a servo motor drives the rotation of the roller, the linear speed of the roller is the same as the transmission speed of the coated paper, the position of the probe is monitored through a position encoding module, and thickness detection is realized by combining a calculation formula. The method comprises the following steps: conveying after coating, preparing a visual area, rotating detection of the probe, matching the speed, calculating the angle, and repeatedly detecting without interruption. The application overcomes the technical defects of traditional vertical detection, such as single detection angle and complicated configuration, can realize multi-angle and uninterrupted detection of the coated paper, improves the detection precision and comprehensiveness, and provides protection for high-quality coated paper production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of production detection of coated paper, and particularly to a coated paper coating thickness online laser detection device and method. BACKGROUND

[0002] In the field of coated paper production, high-quality coated paper has very high requirements for the uniformity and precision of coating thickness, so accurate detection of coating thickness is required. In the prior art, a laser probe is usually used to detect the coating thickness, but a flat array type vertical downward detection method is usually used.

[0003] Although the above detection method can detect the same position of the coated paper multiple times, the detection angle is fixed, the coating effect at the same position cannot be evaluated from multiple angles, abnormal thickness problems caused by differences in coating angles are easily missed, the coating quality cannot be fully and accurately reflected, there are detection limitations, and the high precision and comprehensiveness requirements of coating thickness detection for high-quality coated paper production cannot be met.

[0004] If multiple laser probes with different angles are arranged to detect the coated paper, the detection angle configuration is not only cumbersome, but also the detection method is not continuous, and there are detection defects.

[0005] In summary, how to more comprehensively and accurately detect the coating condition of the coated paper and control the coating quality of the coated paper has become a technical problem to be solved. SUMMARY

[0006] To solve the above technical problems, the present application is realized by the following technical scheme:

[0007] The present application provides a coated paper coating thickness online laser detection device, which comprises a detection assembly, a group of horizontal rollers located downstream of the coating roller below the detection assembly, and a group of horizontal transmission coated papers above the horizontal rollers. The detection assembly is provided with a transversely horizontal roller cylinder, and a plurality of laser probes are arranged at equal intervals on the periphery of the roller cylinder.

[0008] A first shaft box for rotating and supporting the roller cylinder is arranged on one side of the roller cylinder, a second shaft box for rotating and supporting the roller cylinder is arranged on the other side of the roller cylinder, and a servo motor for driving the rotation of the roller cylinder is arranged on the other side of the first shaft box. The rotation direction of the lowest point of the roller cylinder is the same as the horizontal transmission direction of the coated paper above the horizontal rollers, and the linear speed of the rotation of the laser probes driven by the roller cylinder is the same as the linear speed of the transmission of the coated paper.

[0009] The first shaft box is provided with a brush module, and the brush module is electrically connected with a control box. The first shaft box is also provided with a position encoding module for monitoring the rotation position of the laser probes on the periphery of the roller cylinder.

[0010] As a preferred technical scheme of the laser detection device: the roller is located above the middle position of the horizontal transmission section of the laminated paper supported by a group of horizontal rollers. The length of the roller driving the laser probe to rotate one round is less than the length of the horizontal transmission of the laminated paper.

[0011] As a preferred technical scheme of the laser detection device: the position encoding module adopts a grating encoding module, and the number of grating encodings of the position encoding module is the same as the number of laser probes in the same cross section of the roller.

[0012] As a preferred technical scheme of the laser detection device: the roller shaft is fixedly arranged with an inner shaft body cooperating with the brush module to rotate, and the control box is fixedly installed on the inner shaft body. The first shaft box and the second shaft box are provided with bearing mechanisms cooperating with the inner shaft body.

[0013] As a preferred technical scheme of the laser detection device: the control box is provided with a lithium battery unit and a charging module for supplementing the lithium battery unit with electric energy, and the charging module is electrically connected with the brush module through an ADC module.

[0014] As a preferred technical scheme of the laser detection device: the control box is provided with an information transmission module for transmitting detection information, and the information transmission module adopts a 5G signal transmission module.

[0015] The present application provides a laminated paper coating thickness online laser detection method, comprising the following contents:

[0016] Link one, the laminated paper is completed by the coating machine and the coating roller, and then is transmitted to the first horizontal roller and rotated to the horizontal section.

[0017] Link two, the start and end points of the horizontal section transmission of the laminated paper and the shaft center of the roller form a visual area of the laser probe, which is ready for detection.

[0018] Link three, the servo motor drives the roller to rotate, and the roller drives the laser probes arranged at equal intervals on the circumference to rotate synchronously.

[0019] Link four, the servo motor controls the linear speed of the roller driving the laser probe to rotate, which is the same as the linear speed of the laminated paper transmission, so as to improve the accuracy of the detection result of the laser probe.

[0020] Link five, when any one of the laser probes rotates into the visual area range, real-time distance detection of the coating surface of the horizontal section laminated paper is started.

[0021] Link six, the position encoding module cooperates with the monitoring of the rotating position of the laser probe on the circumference of the roller, and determines the relative central angle β of the laser probe entering the visual range based on the vertical center line of the cross section of the roller.

[0022] Step seven, according to the detection standard distance formula Lx= (H / cosβ)-R, judge whether the coating thickness of the corresponding detection point is normal. Wherein, H is the height difference between the roll shaft and the horizontal section of the coated paper, R is the distance from the laser probe to the roll shaft.

[0023] Step eight, under the condition of ensuring that the arc length distance La between adjacent laser probes is less than the multi-detection length Lc, realize the uninterrupted detection of the laser probe to the coated paper and the multi-angle repeated detection of the same point, and comprehensively evaluate the coating effect.

[0024] Wherein, the multi-detection length Lc=Ls-Lm, Ls is the length of the horizontal section of the coated paper, and Lm is the total arc length of any laser probe in the visualization area, Lm=2R·arctan[Ls / (2H)].

[0025] Wherein, the number of times that any point of the coated paper is repeatedly detected is:

[0026] .

[0027] In addition, the on-off control of the laser probe: the roll side laser probe is powered off after completely leaving the visualization area, and the roll side laser probe is powered on and starts working before entering the visualization area.

[0028] Compared with the existing technology, the beneficial effects of the present application are:

[0029] The roll drives the laser probe to rotate, so that the same detection point can be detected by laser probes at different angles multiple times, overcoming the technical defects of single vertical detection angle and complicated angle installation configuration, and the coating effect can be more comprehensively evaluated to avoid missed detection; and the servo motor drives the roll rotation speed to be the same as the transmission speed of the coated paper, reducing the relative speed difference between the laser probe and the detection point, and ensuring the detection accuracy.

[0030] The present application ensures uninterrupted detection by reasonably designing the laser probe spacing and motion parameters, and can repeatedly detect the same position multiple times, combines the precise positioning of the probe position by the position encoding module, realizes rapid and accurate judgment of the coating thickness based on formula calculation, improves the detection efficiency and reliability, and provides a powerful guarantee for high-quality coated paper production. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is the overall layout schematic diagram of the laser detection device of the present application.

[0032] Figure 2 It is Figure 1 The schematic diagram of the local enlargement in A of the figure.

[0033] Figure 3The schematic view of the laser probe for the distance detection of any point of the horizontal transmission coated paper in the application.

[0034] Figure 4 The schematic view of the relative movement between the laser probe and the horizontal transmission coated paper in the application.

[0035] Figure 5 The schematic view of the rotation matching structure between the servo motor and the roller in the application.

[0036] 1-coated paper; 2-coating roller; 3-coating machine; 4-horizontal roller; 5-detection assembly, 501-roller, 502-laser probe (502x-arbitrary laser probe), 503-inner shaft body, 504-control box; 6-first shaft box, 601-brush module, 602-position coding module; 7-second shaft box; 8-servo motor. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and do not limit the application.

[0038] Example one, the application designs a coated paper coating thickness online laser detection device, as shown in Figure 1 , Figure 5 , a set of horizontal rollers 4, a detection assembly 5, the detection assembly 5 includes a roller 501, a plurality of laser probes 502, a control box 504, a servo motor 8 and other components, the specific structure configuration is as follows:

[0039] As shown in Figure 1 , the roller 501 is located above the middle position of the horizontal transmission coated paper 1 section supported by the set of horizontal rollers 4, above the middle position of the horizontal transmission coated paper 1 section supported by the set of horizontal rollers 4, and the horizontal rollers 4 are arranged on the downstream side of the coating roller 2, used to support the horizontal transmission coated paper 1, forming a detection working interval.

[0040] As shown in Figure 2 , Figure 5 , the roller 501 structure: transverse horizontal arrangement, a plurality of laser probes 502 are distributed at equal intervals on the circumference, the roller 501 drives the laser probe 502 to rotate one circle, and the length of the laser probe 502 is less than the length of the horizontal transmission coated paper 1. The shaft center is fixed with an inner shaft body 503, the inner shaft body 503 is matched with the brush module 601 to rotate, and is used to install the control box 504 at the same time.

[0041] As shown in Figure 2 , the laser probe 502 is arranged on the roller 501, and the laser probe 502 is arranged on the roller 501., the rotating direction of the roller 501 lowest point is consistent with the horizontal transmission direction of the laminated paper 1 above the horizontal roller 4, ensuring that the relative speed difference between the laser probe 502 and the detection point of the laminated paper 1 is minimized, and the detection accuracy is improved. In addition, the linear speed of the laser probe 502 driven by the roller 501 is consistent with the transmission linear speed of the laminated paper 1, realizing synchronous motion detection.

[0042] As Figure 5 , the first shaft box 6: one side rotates to support the roller 501, and the other side is provided with a servo motor 8 for driving the roller 501 to rotate; a brush module 601 is configured and electrically connected with a control box 504 to realize power and signal transmission; a position encoding module 602 (using grating encoding, the number of laser probes 502 in the same cross section is the same as the number of grating encodings of the position encoding module 602, ensuring that the position of each probe can be accurately monitored) is integrated to monitor the rotating position of the laser probe 502. The second shaft box 7 is only used to rotate to support the roller 501, and forms a stable support structure with the first shaft box 6. The first shaft box 6 and the second shaft box 7 are connected with the inner shaft body 503 through a bearing mechanism, ensuring the stability and flexibility of the roller 501 rotation.

[0043] As Figure 2 , Figure 5 , the servo motor 8: directly drives the roller 501 to rotate, and matches the linear speed of the laser probe 502 rotation with the transmission linear speed of the laminated paper 1 by accurately controlling the rotating speed.

[0044] As Figure 5 , the control box 504 is fixedly installed on the inner shaft body 503, and the following modules are integrated inside:

[0045] Lithium battery cell, providing device working power. Charging module, connected with the brush module 601 through the ADC module, realizing lithium battery power supplement, of course, the control box can also be powered directly through the ADC. Information transmission module, using 5G signal transmission module, real-time transmission of detection data.

[0046] Example two, the present application designs a laminated paper coating thickness online laser detection method, the main method content is as follows:

[0047] The laminated paper is completed by the coating machine 3 and the coating roller 2, and then is conveyed to the first horizontal roller 4 and rotated to the horizontal section.

[0048] The visual area of the laser probe is formed between the starting and ending points of the horizontal section of the coated paper transmission and the axis of the roller 501, and the area is prepared for detection. When any one of the laser probes 502 reaches the visual area, it starts to detect the real-time distance of the coated paper transmission in the horizontal section. The laser probes 502 on the side of the roller 501 are powered off after completely leaving the visual area, and the laser probes 502 on the side of the roller 501 are powered on and start to work before entering the visual area.

[0049] The servo motor 8 drives the rotation of the roller 501, and the roller 501 drives the synchronous rotation of the laser probes 502 arranged at equal intervals on the side. The servo motor 8 drives the roller 501 to rotate at the same linear speed as the coated paper transmission, which improves the accuracy of the detection results of the laser probes 502.

[0050] Detection working conditions:

[0051] The linear speed of the coated paper transmission and the laser probes 502 is V (the same speed is adopted in the present application, and in the following calculation and analysis, the speed factor is eliminated in some calculations, but when the linear speed of the coated paper transmission and the laser probes 502 is different, the corresponding speed factor cannot be eliminated and needs to be considered additionally).

[0052] The arc length interval between adjacent laser probes 502 is La, the distance of the horizontal section of the coated paper is Ls, Ls>La, and the total time of the travel of any point Xs of the coated paper in the horizontal section is t1=Ls / V.

[0053] The height difference between the axis of the roller 501 and the horizontal section of the coated paper is H, and the visual central angle range of the laser probes 502 on the side of the roller 501 is θ=2arctan[Ls / (2H)].

[0054] The radius of the roller 501 is R (the distance from the laser probe 502 to the axis of the roller 501), and the arc length travel in the visual area is Lm=R·θ.

[0055] The total time of the travel of any laser probe 502 in the visual area is t2=Lm / V=R·θ / V=2R·arctan[Ls / (2H)] / V.

[0056] The length of the multiple detection of any laser probe 502 towards the horizontal section of the coated paper:

[0057] Lc=(t1-t2)·V=Ls-2R·arctan[Ls / (2H)].

[0058] Under the condition of ensuring the arc length interval La between adjacent laser probes 502 is less than the length Lc, the laser probe 502 can continuously detect the coated paper, and can also complete multiple detections of any point of the coated paper, and the angle position of the any point of the coated paper detected is also different (more comprehensive detection of the coated paper coating).

[0059] The number of times of repeated detection of the any point of the coated paper is:

[0060] .

[0061] By the position coding module, the rotating position of any one laser probe 502 is judged, for example, Figure 3 With the vertical center line of the cross section of the roller 501 as a reference, the relative angle of the laser probe 502 entering the visual range to the center of the circle is β, and the reference standard distance Lx of the detected coated paper is (H / cosβ)-R. When the detection standard is met, it is determined that the thickness of the corresponding detected coated paper coating position point is normal. Otherwise, it is not normal.

[0062] In the present application, the roller 501 is designed to rotate in the same direction as the conduction direction of the coated paper, so as to reduce the relative speed difference between the laser probe 502 and the detection point of the coated paper. The greater the relative speed difference, the shorter the detection time of the laser probe 502 (aperture) to the detection point. The smaller the relative speed difference, the longer the detection time of the laser probe 502 (aperture) to the detection point, which is beneficial to more accurate detection. Therefore, although the roller 501 rotates in the opposite direction of the conduction direction of the coated paper, it can greatly increase the number of times of repeated detection of any point of the coated paper and the different detection angles, but it greatly reduces the detection accuracy, and therefore, the reverse motion cooperation mode is not suitable.

[0063] The following specific parameter reference examples are used to deduce the detection process of the dynamically rotating laser probe 502 to the horizontally transmitted coated paper:

[0064] It is assumed that Ls=1m (the length of the horizontal section of the coated paper), R=0.1m (the distance from the laser probe 502 to the axis of the roller 501), H=0.15m (the height difference between the axis of the roller 501 and the horizontal section of the coated paper), and the number of laser probes 502 in the same cross section is 20.

[0065] (I) Calculate the arc length interval La between adjacent laser probes 502: La=2πR / 20=0.01πm≈0.0314m.

[0066] (II) Calculate the visual central angle: θ=2arctan[Ls / (2H)]=2arctan[1 / (2*0.15)]=2arctan (1 / 0.3)≈2*1.249 rad=2.498 rad.

[0067] (III) Calculate the visual arc length travel Lm=R·θ=0.1*2.4980=0.2498m.

[0068] (iv) Calculate the length of the multi-detector Lc=Ls-Lm=1-0.2498=0.7502m.

[0069] (v) Calculate the number of times the probe is repeated. The number of times any point on the coated paper was repeatedly probed by different laser probes 502 from different angles was 23.

[0070] like Figure 3 , Figure 4 When any point Xs of the coated paper reaches the horizontal section, the laser probe at position 502x detects the position information of that point on the coated paper. As the roller 501 rotates and the coated paper is horizontally driven, when the laser probe at position 502x leaves the position point Xs of the coated paper and continuously scans and detects the downstream area of ​​the position Xs of the coated paper, the laser probe originally located behind position 502x also begins to detect the position point Xs of the coated paper, and the detection angle is different from that of the laser probe at position 502x. In this way, the position point Xs of the coated paper will be detected by more laser probes 502 around the roller 501 at different angles during the horizontal transmission process, and the position point Xs of the coated paper will be detected more comprehensively and accurately.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An online laser detection device for coating thickness of coated paper, characterized in that: a detection assembly (5) is provided below a group of horizontal rollers (4) located on the downstream side of a coating roller (2), and a horizontal transmission coated paper (1) is arranged above the group of horizontal rollers (4); the detection assembly (5) is provided with a transverse horizontal roller cylinder (501), and a plurality of laser probes (502) are arranged at equal intervals on the circumferential side of the roller cylinder (501); one side of the roller cylinder (501) is provided with a first shaft box (6) for rotating to support the roller cylinder (501), and the other side is provided with a second shaft box (7) for rotating to support the roller cylinder (501); the other side of the first shaft box (6) is provided with a servo motor (8) for driving the roller cylinder (501) to rotate; wherein the rotation direction of the lowest point of the roller cylinder (501) is the same as the horizontal transmission direction of the coated paper (1) above the horizontal roller (4); wherein the linear speed of the roller cylinder (501) driving the laser probe (502) to rotate is the same as the linear speed of the coated paper (1) transmission; the first shaft box (6) is provided with a brush module (601), and the brush module (601) is electrically connected with a control box (504); the first shaft box (6) is further provided with a position encoding module (602) for monitoring the rotating position of the laser probe (502) on the circumferential side of the roller cylinder (501).

2. The online laser detection device for coating thickness of coated paper according to claim 1, characterized in that: the roller cylinder (501) is located directly above the middle position of the horizontal transmission coated paper (1) section supported by the group of horizontal rollers (4) above; the circumference of the roller cylinder (501) driving the laser probe (502) to rotate one round is smaller than the length of the horizontal transmission of the coated paper (1).

3. The online laser detection device for coating thickness of coated paper according to claim 1, characterized in that: the position encoding module (602) adopts a grating encoding module, and the number of grating encodings of the position encoding module (602) is the same as the number of laser probes (502) in the same cross section of the roller cylinder (501).

4. The online laser detection device for coating thickness of coated paper according to claim 1, characterized in that: the roller cylinder (501) is fixedly provided with an inner shaft body (503) for rotating with the brush module (601), and the control box (504) is fixedly installed on the inner shaft body (503); the first shaft box (6) and the second shaft box (7) are provided with a bearing mechanism for cooperating with the inner shaft body (503).

5. The online laser detection device for coating thickness of coated paper according to claim 1, characterized in that: the control box (504) is provided with a lithium battery unit and a charging module for supplementing electric energy to the lithium battery unit, and the charging module is electrically connected with the brush module (601) through an ADC module.

6. The online laser detection device for coating thickness of coated paper according to claim 1, characterized in that: the control box (504) is provided with an information transmission module for transmitting detection information, and the information transmission module adopts a 5G signal transmission module. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7. A method for on-line laser detection of the coating thickness of a coated paper, characterized in that The online laser detection device for coated paper thickness according to any one of claims 1 to 6 includes the following: In the first step, the coated paper (1) is coated by the coating machine and coating roller (2), and then conveyed to the first horizontal roller (4) and rotated to the horizontal section; In the second step, the starting and ending points of the horizontal section of the coated paper (1) and the axis of the roller (501) form a visualization area for the laser probe (502), which is prepared for the detection. In the third step, the servo motor (8) drives the roller (501) to rotate, and the roller (501) drives the laser probes (502) arranged at equal intervals on the periphery to rotate synchronously; In step four, the linear speed at which the servo motor (8) drives the roller (501) to rotate the laser probe (502) is the same as the linear speed at which the coated paper (1) is driven, thereby improving the accuracy of the detection results of the laser probe (502). Step 5: When any laser probe (502) rotates into the visualization area, it begins to perform real-time distance detection on the coating surface of the horizontal section of coated paper (1). Step 6: The position coding module (602) works in conjunction with the rotation position of the laser probe (502) on the periphery of the monitoring roller (501) to determine the relative angle β between the laser probe (502) and the center of the circle that enters the visualization range, with the vertical center line of the roller (501) as the reference. Step 7: Based on the standard detection distance formula Lx=(H / cosβ)−R, determine whether the coating thickness at the corresponding detection point is normal; Where H is the height difference between the axis of the roller (501) and the horizontal section of the coated paper (1), and R is the distance from the laser probe (502) to the axis of the roller (501); Step 8: Under the condition that the arc length spacing La between adjacent laser probes (502) is less than the multi-detection length Lc, the laser probe (502) can perform uninterrupted detection of the coated paper (1) and repeated detection at the same point from multiple angles to comprehensively evaluate the coating effect. Among them, the multi-detection length Lc=Ls-Lm, Ls is the horizontal segment length of the coated paper (1), Lm is the total arc length of any laser probe in the visualization area, Lm=2R·arctan[Ls / (2H)]; The number of times any point on the coated paper (1) is repeatedly probed is: 。 8. The online laser detection method for coating thickness of coated paper according to claim 7, characterized in that: The power is turned off after the laser probe (502) on the periphery of the roller (501) is completely removed from the visualization area, and the power is turned on to start working before the laser probe (502) on the periphery of the roller (501) enters the visualization area.

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