A method for edge coating and coinciding head and tail adhesive lines

Abstract

A method for aligning the beginning and end adhesive lines in edge coating, relating to the field of edge coating technology, involves gradually increasing the adhesive output in the initial segment to form a starting adhesive line that transitions from thin to wide; and gradually decreasing the adhesive output in the final segment to form a converging final adhesive line that narrows from wide to thin. The method ensures that the starting and ending adhesive lines coincide at the same coating trajectory position, forming a continuous, closed edge adhesive line. In the initial segment, the adhesive output is gradually increased through acceleration control and needle gap adjustment; in the final segment, the movement speed is gradually reduced and the needle-to-coating surface gap is simultaneously increased through multi-segment idle-walking control, while performing back-wiping and back-suction processes. This achieves seamless overlap of the beginning and end of the edge coating, avoiding adhesive buildup at the starting point and stringing at the ending point, ensuring that the width and height of the adhesive line at the overlap are consistent with the straight edge segment, meeting the subsequent bonding accuracy requirements.

Description

Technical Field

[0001] This application relates to the field of border coating technology, and in particular to a method for aligning the first and last adhesive lines of border coating. Background Technology

[0002] In the bezel coating process, adhesive is typically applied continuously along rectangular or other closed-shaped tracks to form a sealing or bonding line; this process is often referred to as "creating a dam." After pressing, the applied adhesive line forms a sealed structure, and its final adhesive width and height are key indicators of coating accuracy. If the adhesive line width or height does not meet design requirements, it will directly affect the reliability of subsequent bonding processes, leading to issues such as poor bonding, adhesive overflow and contamination, adhesive being squeezed out of the display area, seal failure, uneven adhesive line height causing differences in bonding thickness, resulting in uneven display optics, and residual air bubbles.

[0003] Because the coating start and end points need to converge at the same location, improper control of the amount of adhesive at the start and end points can easily lead to adhesive buildup at the overlap, resulting in excessive local height, adhesive overflow or insufficient adhesive after pressing, and obvious seams. This causes the width and height of the adhesive line at the overlap point to deviate from the standard value of the straight edge section, disrupting the consistency of the entire dam. In existing technologies, a common practice is to set an overlap zone between the start and end points, reducing the amount of adhesive at the end point by simply slowing down or closing the adhesive application early. However, due to the rheological properties of the adhesive and the inertia of the needle movement, the starting adhesive tip is often too thick, and the end point is prone to stringing. After overlap, a "big head" or depression is formed, making it difficult to ensure that the overlap point has the same width and height as the straight edge section.

[0004] Furthermore, the difficulty in simultaneously observing the independent shapes of the starting and ending points during the debugging phase increases the challenge of process optimization. Therefore, there is an urgent need for a method to seamlessly overlap the beginning and end of the border coating, ensuring that the starting adhesive line gradually widens and the ending adhesive line gradually narrows, and that they smoothly connect at the same trajectory position. This guarantees that the width and height of the entire closed border adhesive line are uniform, meeting the requirements of subsequent bonding processes. Summary of the Invention

[0005] This invention provides a method for overlapping the beginning and end adhesive lines in border coating, aiming to solve the problem of poor adhesive form at the overlap of the starting and ending points in the existing coating process, resulting in uneven width and height, and to achieve continuous, uniform, and seamless closed border adhesive lines, thus ensuring the quality of subsequent bonding.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows: This invention provides a method for aligning the first and last adhesive lines of a border coating, used for continuous coating along a closed coating trajectory, comprising: S1. Gradually increase the amount of adhesive in the initial segment of the coating trajectory to form an initial adhesive line that transitions from thin to wide. S2. Gradually reduce the amount of adhesive in the second segment of the coating trajectory to form a tapering termination line that tapers from wide to narrow. S3. Control the starting glue line and the ending glue line to coincide at the same coating trajectory position to form a continuous and closed border glue line.

[0007] Furthermore, in the initial stage, the amount of adhesive is gradually increased by controlling the coating acceleration and adjusting the gap between the dispensing end of the needle and the coating surface.

[0008] Furthermore, the acceleration control of the initial segment includes a first initial acceleration, a second initial acceleration, and a normal coating acceleration; the first initial acceleration is greater than the normal coating acceleration, and the second initial acceleration is less than the first initial acceleration and approaches the normal coating acceleration.

[0009] Furthermore, the gap adjustment in the starting section includes the step of setting the gap drop amount when the glue is opened at the starting point and the continuous distance of the gap drop amount, so as to reduce the gap between the glue outlet end of the needle and the coating surface.

[0010] Furthermore, the termination section includes a step of gradually reducing the movement speed and simultaneously raising the needle tip through multi-segment idle movement segment control to increase the gap between the dispensing end of the needle tip and the coating surface.

[0011] Furthermore, the multi-segment idle travel segment control includes setting the idle travel distance after the coating endpoint, dividing the idle travel distance into multiple continuous segments, and independently setting the needle movement speed ratio, needle lifting amount, and the gap between the needle dispensing end and the coating surface for each segment.

[0012] Furthermore, the sum of the idle travel distances of the segments is 1, and the movement speed of each segment gradually decreases from the normal coating speed to the glue breaking speed.

[0013] Furthermore, after the termination segment ends, the steps of back-wiping and back-suction are performed.

[0014] Furthermore, the back-wiping process includes moving in the opposite direction along the coating trajectory at a preset back-wiping distance after the adhesive is closed, and scraping off the residual adhesive at the endpoint.

[0015] Furthermore, the back-suction process includes performing a vacuum back-suction of the valve body after the adhesive is cut off, sucking back the remaining adhesive on the surface of the needle until it is flush with the adhesive outlet surface of the needle.

[0016] Furthermore, the program also includes the debugging steps, which include setting the offset of the dispensing surface of the needle relative to the vertical coating direction so that the starting glue line and the ending glue line are misaligned in the vertical direction; after debugging, the offset is set to zero so that the starting glue line and the ending glue line completely coincide at the same trajectory position. Beneficial effects

[0017] The beneficial technical effects of this invention are as follows: During the adhesive coating process, the adhesive output is gradually increased at the beginning to form a thin initial adhesive line, avoiding adhesive buildup at the starting point and ensuring that the width and height of the initial adhesive line gradually transition to normal values; the adhesive output is gradually decreased at the end, combined with multi-segment idle deceleration and needle lifting, to achieve smooth adhesive breakage, with no stringing or large ends at the end, and the width and height of the end adhesive line gradually converge; the starting and ending adhesive lines coincide at the same trajectory position, and the width and height of the overlapping adhesive line are consistent with the straight edge section, resulting in a uniform and seamless dam after pressing, meeting the accuracy requirements of subsequent bonding, and avoiding poor bonding, adhesive overflow pollution (i.e., adhesive being squeezed out and spilled into the display area), sealing failure, or uneven adhesive line height causing differences in bonding thickness and resulting in air bubble residue, etc.; during the debugging stage, an offset can be set to separate the starting and ending points, facilitating separate optimization of the shape, and returning to zero after debugging ensures the overlap accuracy, reducing the difficulty of process debugging. Attached Figure Description

[0018] To more clearly illustrate the technical solution proposed by the present invention, a detailed description is provided below in conjunction with the embodiments and accompanying drawings. It should be understood that the accompanying drawings described below are merely some embodiments of the present invention, and those skilled in the art can make changes to these drawings under the concept of the present invention.

[0019] Figure 1 A schematic diagram of the coating trajectory provided by the present invention; Figure 2 This is a schematic diagram of the start and end segments of the debugging phase in an embodiment of the present invention.

[0020] 1. Starting point; 2. Starting segment; 3. Ending segment. Detailed Implementation

[0021] This invention provides a method for overlapping the first and last adhesive lines of a border coating. The following detailed description of the invention is based on specific implementation processes.

[0022] When implementing this invention, the workpiece to be coated is first fixed on the worktable of the coating equipment. The motion control system, dispensing valve and needle of the equipment have been pre-calibrated. A closed rectangular coating trajectory is set, with the coating direction being clockwise. The starting point (1) and the ending point are set at the midpoint of the long side of the rectangle.

[0023] The initial stage (2) is gradually controlled. At the same time as the adhesive is released at the starting point (1) of the coating, the movement speed of the needle is rapidly increased from zero and then gradually transitioned through acceleration control. Specifically, two initial accelerations are set. The first initial acceleration is greater than the acceleration of the normal coating stage, so that the needle starts quickly to overcome the initial viscous resistance of the adhesive. The second initial acceleration is less than the first initial acceleration and approaches the normal coating speed to avoid the impact of adhesive volume caused by sudden speed changes. At the same time, the needle gap is adjusted: the gap drop amount and the continuous distance of the drop amount are set when the adhesive is released at the starting point (1). In the first part of the initial stage (2), the gap between the needle and the coating surface is made smaller than the normal coating gap, thereby reducing the initial amount of adhesive. As the needle continues to move, the gap gradually returns to the normal value, and the amount of adhesive is increased from less to more, forming an initial adhesive line that transitions from thin to wide. For example, the normal coating speed is 30 mm / s and the normal coating acceleration is 1000 mm / s². The initial acceleration for the first segment is set to 2000 mm / s², and the initial acceleration for the second segment is set to 800 mm / s². The gap descent is set to 0.1 mm, and the duration is set to 0.5 mm. Under these parameters, the initial glue line is thin and without glue buildup, gradually transitioning to normal width and height.

[0024] Then it enters the stable coating section, where the needle moves at a constant speed along the rectangular coating trajectory with normal coating speed and normal coating gap, and the width and height of the adhesive line remain constant.

[0025] When the coating is close to the end point, the termination segment (3) is gradually reduced. The movement speed is gradually reduced and the gap between the needle and the coating surface is increased simultaneously through multi-segment idle travel segment control. The specific implementation method is as follows: the total idle travel distance after the coating end point is set, and the idle travel distance is divided into multiple continuous segments. Each segment is independently configured with distance ratio, movement speed ratio, needle lifting amount and gap value between the needle and the coating surface. The sum of the distance ratios of each segment is 100%, and the speed of each segment gradually decreases from the normal coating speed to the glue cutting speed. During this process, the needle gradually rises, the glue discharge gradually decreases, and the gap between the needle and the coating surface gradually increases, forming a termination glue line that converges from wide to narrow.

[0026] For example, setting the total distance traveled without moving the needle to 5mm, it is divided into four consecutive segments. The first segment accounts for 20% of the distance (actual distance 1mm), with a movement speed of 80% (24mm / s), a needle lift of 0.2mm, and a gap increase of 0.2mm. The second segment accounts for 20% of the distance (actual distance 1mm), with a speed of 50% (15mm / s), a needle lift of 0.3mm, and a gap increase of 0.3mm. The third segment accounts for 20% of the distance (actual distance 1mm), with a speed of 30% (9mm / s), a needle lift of 0.4mm, and a gap increase of 0.4mm. The fourth segment accounts for 40% of the distance (actual distance 2mm), with a speed of 10% (3mm / s), a needle lift of 0.5mm, and a gap increase of 0.5mm. The speed of each segment gradually decreases from 30mm / s to 3mm / s, and the width and height of the termination adhesive line gradually converge to a thinner point.

[0027] Close the glue valve upon reaching the endpoint. Subsequent back-wiping involves moving the nozzle a distance in the opposite direction of the coating path, scraping away any remaining glue at the endpoint to prevent glue nodules. For example, the back-wiping distance is set to 1.5mm. Back-suction involves activating the valve's vacuum back-suction function to draw back any remaining glue from the needle tip until it is flush with the needle tip, preventing dripping or stringing due to gravity or surface tension after the glue is closed. After completing the above coating and post-treatment, the starting and ending glue lines naturally overlap at the same trajectory position. Because the starting glue line is tapered at the beginning and the ending glue line is tapered at the end, the two lines merge to form a smooth transition, without glue buildup, depressions, or visible seams. After subsequent pressing, the width and height of the overlapping glue line remain consistent with the straight edge section.

[0028] During the debugging phase before formal production, the offset separation method can be used to optimize the shape of the beginning and end of the coating. The specific implementation method is as follows: set an offset perpendicular to the coating direction, for example, 0.3mm, so that the trajectory of the starting glue line and the ending glue line are staggered in the vertical direction, thereby observing and adjusting the gradual increase shape of the starting glue line and the gradual decrease shape of the ending glue line respectively. The debugging personnel can independently adjust the acceleration value, gap descent amount and continuous distance of the starting segment (2), as well as the number of idle segments, distance ratio and speed ratio of each segment, back-wiping distance and back-suction intensity of the ending segment (3). After the starting glue line and the ending glue line have reached the ideal shape, the offset is set to zero. At this time, the starting glue line and the ending glue line precisely coincide on the same trajectory position, and mass production can be started.

[0029] Through the above implementation methods, the present invention achieves seamless overlap of the beginning and end of the rectangular border coating, effectively avoiding glue buildup at the starting point and stringing at the end point, ensuring that the width and height of the entire dam are uniform and consistent, and meeting the precision requirements of the subsequent bonding process.

[0030] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of frame coating and head-tail adhesive line overlap for continuous coating on a closed coating trajectory, characterized in that, Including the following steps: S1. Gradually increase the amount of adhesive in the initial segment (2) of the coating trajectory to form an initial adhesive line that transitions from thin to wide. S2. The amount of the second adhesive in the termination segment (3) of the coating trajectory is gradually reduced to form a termination adhesive line that converges from wide to narrow. S3. Control the starting adhesive line and the ending adhesive line to coincide at the same coating trajectory position to form a continuous and closed border adhesive line.

2. The method for aligning the first and last adhesive lines of the border coating according to claim 1, characterized in that, In the initial section (2), the amount of the first adhesive is gradually increased by controlling the coating acceleration and adjusting the gap between the dispensing end of the needle and the coating surface.

3. The method for aligning the first and last adhesive lines of the border coating according to claim 2, characterized in that, The acceleration control of the initial segment (2) includes a first initial acceleration, a second initial acceleration, and a normal coating acceleration; the first initial acceleration is greater than the normal coating acceleration, and the second initial acceleration is less than the first initial acceleration and approaches the normal coating acceleration.

4. The method for aligning the first and last adhesive lines of the border coating according to claim 3, characterized in that, The gap adjustment in the starting section (2) includes setting the gap drop amount when the glue is opened at the starting point (1) and the continuous distance of the gap drop amount, so as to reduce the gap between the glue outlet end of the needle and the coating surface.

5. The method for aligning the first and last adhesive lines of the border coating according to claim 1, characterized in that, The termination section (3) includes a step of gradually reducing the movement speed and simultaneously raising the needle tip by multi-segment idle movement segment control, so as to increase the gap between the dispensing end of the needle tip and the coating surface.

6. The method for aligning the first and last adhesive lines of the border coating according to claim 5, characterized in that, The multi-segment idle travel segment control includes setting an idle travel distance after the coating endpoint, dividing the idle travel distance into multiple continuous segments, and independently setting the percentage of the needle's movement speed, the amount of the needle's lift, and the gap between the needle's dispensing end and the coating surface for each segment.

7. The method for aligning the first and last adhesive lines of the border coating according to claim 6, characterized in that, The sum of the idle travel distances of the segments is 1, and the movement speed of each segment gradually decreases from the normal coating speed to the glue breakage speed.

8. The method for aligning the first and last adhesive lines of the border coating according to any one of claims 1-7, characterized in that, This includes the steps of performing back-wiping and back-absorption after the termination segment (3) ends.

9. The method for aligning the first and last adhesive lines of the border coating according to claim 8, characterized in that, The back-wiping process includes moving in the opposite direction along the coating trajectory at a preset back-wiping distance after the adhesive is closed, and scraping off the residual adhesive at the endpoint.

10. The method for aligning the first and last adhesive lines of the border coating according to claim 8, characterized in that, The back-suction process includes performing a vacuum back-suction of the valve body after the adhesive is cut off, sucking back the remaining adhesive on the surface of the needle until it is flush with the adhesive outlet surface of the needle.

11. The method for aligning the first and last adhesive lines of the border coating according to claim 8, characterized in that, It also includes a debugging step, which includes setting the offset of the dispensing surface of the needle from the vertical coating direction so that the starting glue line and the ending glue line are misaligned in the vertical direction; after debugging, the offset is set to zero so that the starting glue line and the ending glue line completely coincide at the same trajectory position.

Images