Laser cutting method for surface film material of glass finished product

Abstract

The invention discloses a laser cutting method for a surface film material of a glass finished product, and belongs to the technical field of laser cutting. According to the scheme, the laser is selected according to the laser transmittance of the membrane material, the glass and the coating; a short-focus focusing lens is selected to determine the laser frequency and the cutting speed, the cut-through threshold value of the film material and the damage threshold value of the glass in various defocusing modes are measured, and the minimum standard light spot diameter is determined according to the edge cutting effect; then determining the cutting frequency and the cutting power of each time according to each threshold value and the laser transmittance of the film material; and a focusing lens with a proper focal length and a defocusing mode are selected according to parameters such as the power interval, the debugging difficulty and the minimum standard light spot diameter. According to the scheme, on the premise that glass and a coating are not damaged, the film material on the surface of the glass finished product can be cut for one time or multiple times, the feasibility that the film material is attached to the surface of the glass finished product in a hot attaching mode and then the redundant film material is cut through laser is greatly enhanced, and the method is more suitable for large-scale production and application.

Description

Technical Field

[0001] The invention relates to the technical field of laser cutting, and in particular to a method for laser cutting a film material on the surface of a finished glass product. Background Art

[0002] There are two main ways to cut film materials with lasers: ablation cutting and melting cutting. Both methods use lasers to act directly on the material, but the impact of the laser on the lower layer of the film may cause process damage. For film products, two cutting methods are usually used in the market: semi-transparent cutting and full-transparent cutting. Semi-transparent cutting is mainly used for products such as label paper. Laser cutting forms obvious cuts on the base film, but the film itself is not completely cut off. Full-transparent cutting is often used for products such as mobile phone film stickers. The film is completely cut into shape by laser and then attached to the target surface, such as a mobile phone screen.

[0003] However, the traditional method of cutting first and then laminating has some limitations, mainly reflected in the problems of insufficient positioning accuracy of the film material after laminating and easy generation of bubbles, which usually cannot meet the requirements of high-quality products. Especially for products such as 3D glass products that have extremely high quality requirements, these problems are particularly prominent. Therefore, a new laminating method has emerged, that is, first laminating a film material slightly larger than the size of the glass product to the surface of the glass product by heat laminating, and in the process of laminating, the bubbles between the film material and the glass product are removed by vacuuming, and then the excess film material on the edge of the glass product is removed by laser. However, the film material is usually like Figure 1 For the multi-layer composite structure shown, according to the product quality requirements, the size of the film needs to be slightly smaller than that of the glass product, and the edge cutting effect of the film is also very high. Some glass products also have functional coatings on the bottom surface, which requires the laser to just cut through the film without damaging the glass and coating, and the edge cutting effect of the film must meet the requirements. How to select appropriate laser cutting parameters according to the characteristics of the film, glass, and coating to achieve the above cutting effect is an urgent problem to be solved. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the above-mentioned defects of the prior art, a method for laser cutting of film material on the surface of a finished glass product is provided, in which the film material attached to the surface of the finished glass product is cut by laser.

[0005] To achieve the above object, the present invention provides a method for laser cutting a film material on the surface of a finished glass product, wherein a film material is attached to the upper surface of the finished glass product and a functional coating is adhered to the lower surface. The method comprises the following steps:

[0006] Step S1, selecting a laser that causes minimal damage to the coating according to the transmittance of the film material, glass, and coating to the laser;

[0007] Step S2: Select a short - focus focusing lens and an adjustable beam expander to cut the film material, determine the laser power threshold for cutting through the film material, and then determine the optimal laser frequency and the optimal cutting speed based on the laser power threshold, and set the optimal laser frequency and the optimal cutting speed for all subsequent steps;

[0008] Step S3: Under various defocusing methods, measure the penetration power threshold P1 of the film material and the spot diameter corresponding to the penetration power threshold, and determine the minimum qualified spot diameter Dmin when the edge cutting effect meets the standard;

[0009] Step S4: Under various defocusing methods, measure the damage power threshold P2 of the glass with no film material attached to its upper surface;

[0010] Step S5: Measure the laser power fluctuation percentage M;

[0011] Step S6: Measure the ortho - focus spot diameter Da of the focusing lens with different focal lengths;

[0012] Step S7: Determine the cutting method and cutting power according to the penetration power threshold P1 of the film material, the damage power threshold P2 of the glass, and the laser power fluctuation percentage M under various defocusing methods:

[0013] If P1 < P2, cut once, and the range of the cutting power P is: P1*(1 + M) < P < P2*(1 - M);

[0014] If P1 ≥ P2, cut multiple times. The cutting power of the last time is Pz, and the cutting power of the previous n times is Pc1, where:

[0015] Pz < P2*(1 - M);

[0016] The method for determining Pc1 is:

[0017] Determine the number of cuts before the last cut H is the total thickness of the film material, Hz is the cutting depth corresponding to the power Pz, Hc is the cutting depth corresponding to the power τ1 is the transmittance of the film material to the laser in the laser;

[0018] Determine the cutting depth Hn of the previous n times, and determine the cutting power Pc1 of the previous n times according to the cutting depth Hn of the previous n times: The cutting depth of the previous n times Take Pc as the upper limit and make a laser power - cutting depth gradient curve downwards to find the laser power value Pc1 corresponding to the cutting depth Hn;

[0019] Step S8: Select a focusing lens with a suitable focal length and a defocusing method, and use the determined cutting method and cutting power to cut the film material;

[0020] If only one cutting is required, calculate the power range Pa of the laser cutting power under various defocusing modes, and select the focusing lens with the appropriate focal length and defocusing mode based on the size of the power range Pa under each defocusing mode, the difficulty of debugging various defocusing modes, the minimum standard spot diameter Dmin, and the positive focus spot diameter Da;

[0021] If multiple cuttings are required, re-measure the corresponding minimum standard spot diameter Dmin according to the maximum cutting power, and then select the focusing lens and defocusing method with appropriate focal length based on the size of the power range Pa corresponding to the maximum cutting power, the debugging difficulty of various defocusing methods, the minimum standard spot diameter Dmin, and the positive focus spot diameter Da.

[0022] Preferably, in the step S8, before the film material is cut using the determined cutting method and cutting power, the step further includes:

[0023] Change the beam expander magnification to fine-tune the spot diameter and adjust the laser cutting power according to the cutting effect.

[0024] Preferably, the specific method of changing the beam expander magnification to fine-tune the spot diameter and adjust the laser cutting power according to the cutting effect is: increase the beam expander magnification of the beam expander, use a film-coated glass product to perform gradient verification on different beam expander magnifications, record the film material's cutting power threshold P1, the glass's damage power threshold P2, the spot diameter and the cutting effect under different beam expander magnifications, select the beam expander magnification whose cutting effect meets the expected one, and determine the laser cutting power according to the film material's cutting power threshold P1 and the glass's damage power threshold P2 corresponding to the beam expander magnification.

[0025] Preferably, in step S2, the focal length of the focusing lens is 50 mm, and the beam expansion factor of the beam expander is set to 2 times.

[0026] Preferably, in step S5, the laser power fluctuation percentage = (maximum power value - minimum power value) / average power value.

[0027] Preferably, in step S5, the laser power fluctuation percentage is measured at the film material cutting-through power threshold P1.

[0028] Preferably, in step S8, the method for selecting a focusing lens with a suitable focal length and a defocusing mode includes: if the power intervals Pa under each defocusing mode are not much different, selecting a focusing lens with a focal length whose positive focus spot diameter Da is smaller than and closest to the minimum qualified spot diameter Dmin.

[0029] Preferably, after step S5, the method further includes:

[0030] Determine the damage power threshold P3 of the coating. If multiple lasers are determined in step S1, select a suitable laser based on the damage power threshold P2 of the glass without the film material attached, the damage power threshold P3 of the coating, and the transmittance τ2 of the glass to the laser in the laser.

[0031] The present invention has the following beneficial effects: the scheme of the present invention selects the laser that causes the least damage to the coating according to the transmittance of the film material, glass, and coating to the laser; selects a short-focus focusing lens to determine the optimal laser frequency and the optimal cutting speed, measures the film material's cutting threshold, the glass's damage threshold, and the corresponding spot diameter under various defocusing methods, and determines the minimum standard spot diameter according to the edge cutting effect; then determines the number of cuts and the cutting power for each cut according to the film material's cutting threshold, the glass's damage threshold, and the film material's transmittance to the laser; then comprehensively considers the power range, debugging difficulty, the minimum standard spot diameter, and the positive focus spot diameter of different focal lengths, and selects a focusing lens with a suitable focal length and a defocusing method; finally, the determined cutting method and cutting power are used to cut the film material. The scheme of the present invention can cut the film material on the surface of the finished glass product once or multiple times without damaging the glass and coating. This scheme greatly enhances the feasibility of attaching the film material to the surface of the finished glass product by thermal bonding and then using a laser to cut the excess film material, making it more suitable for large-scale production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 Schematic diagram of the composite membrane structure.

[0034] Figure 2 A schematic structural diagram of a finished glass product with a film material and a coating provided in an embodiment of the present invention.

[0035] Figure 3 A schematic diagram of the steps of a method for laser cutting a film material on the surface of a finished glass product provided in an embodiment of the present invention.

[0036] Figure 4 A schematic diagram of the laser defocusing principle provided by an embodiment of the present invention.

[0037] Figure 5 A schematic diagram of measuring the laser spot diameter provided in an embodiment of the present invention.

[0038] Figure 6 A schematic diagram of laser damage threshold verification provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the specification. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0041] The present invention is suitable for removing excess film material from the surface of a finished glass product, wherein the film material is attached to the upper surface of the finished glass product and the functional coating is attached to the lower surface. Figure 2 The figure shows a schematic diagram of the structure of a finished glass product with a film material and a coating provided by an embodiment of the present invention. In some embodiments of the present invention, the functional coating is a silk-screen ink layer.

[0042] like Figure 3 As shown, an embodiment of the present invention provides a method for laser cutting a film material on the surface of a finished glass product, the method comprising the following steps:

[0043] Step S1, selecting a laser that causes the least damage to the coating according to the transmittance of the film material, glass, and coating to the laser.

[0044] If the coating has low transmittance to lasers of all wavelengths, it will easily absorb the laser and cause damage. To protect the coating from being damaged, a CO2 laser with low transmittance to glass can be selected.

[0045] If the coating has a high transmittance to lasers in certain wavelength bands, such as being able to withstand ultraviolet lasers, green lasers or lasers in other wavelength bands, lasers in the corresponding wavelength bands can be selected.

[0046] Step S2, select a short-focus focusing lens and an adjustable beam expander to cut the film material, determine the laser power threshold for cutting through the film material, and then determine the optimal laser frequency and the optimal cutting speed based on the laser power threshold, and set the optimal laser frequency and the optimal cutting speed for all subsequent steps.

[0047] The purpose of step S2 is to determine the optimal laser frequency and the optimal cutting speed. The reason for using a short-focus focusing lens is that the shorter the focal length, the smaller the spot after focusing, the smaller the focal depth, and the faster the spot changes when defocused, which is conducive to speeding up the verification process. In some embodiments of the present invention, in step S2, the focal length of the focusing lens is 50mm, and the beam expansion multiple of the beam expander is set to 2 times.

[0048] In an embodiment of the present invention, in step S2, the method of determining the laser power threshold for cutting through the film material, and then determining the optimal laser frequency and the optimal cutting speed based on the laser power threshold is: first directly cut the film material with high power, and then make a power gradient until the laser power threshold that just cuts through the film material is found; after determining the laser power threshold for cutting through the film material, set the laser power to the determined laser power threshold for cutting through the film material, and perform gradient verification of frequency and speed in turn to determine the optimal laser frequency and the optimal cutting speed.

[0049] Step S3, measuring the cutting power threshold P1 of the film material and the spot diameter corresponding to the cutting power threshold under various defocusing modes, and determining the minimum standard spot diameter Dmin for achieving the standard edge cutting effect;

[0050] like Figure 4 As shown in the figure, with positive focus as the benchmark, positive and negative defocus gradients are verified. Under various defocusing modes, the laser is directly projected onto the film material, and the power threshold of the laser cutting through the film material under the corresponding defocusing state is recorded, and the spot diameter is measured. Figure 5 As shown, in some embodiments of the present invention, the method for measuring the spot diameter is: use 3M paper as a cross line, measure the line width, and confirm the line uniformity and the spot diameter.

[0051] In the embodiment of the present invention, the edge cutting effect is evaluated based on whether it is cut through, the smoothness, and the size of the heat-affected zone. The standards for meeting the standards are: no residue on the edge, no jaggedness under the naked eye, heat-affected zone <0.05mm, no edge flipping, and bright edge <0.02mm under strong light.

[0052] In an embodiment of the present invention, a method for determining a minimum qualified spot diameter D for achieving a qualified edge cutting effect is as follows: judging whether the edge cutting effect meets the standard when the laser power is the cutting-through power threshold P1 of the film material under each defocus mode, and selecting the smallest spot diameter among the laser spot diameters corresponding to the cutting-through power threshold P1 values ​​of all qualified film materials as the minimum qualified spot diameter D.

[0053] Step S4, measuring the damage power threshold P2 of the glass without film material attached to the upper surface under various defocusing modes.

[0054] In the embodiment of the present invention, the specific method for measuring the damage power threshold P2 of the glass without film attached to the upper surface is: directly hit the glass without film attached with laser, first directly cut the glass with high power, and then make power gradient until the laser power threshold that just cuts the glass is found. Figure 6 As shown, in some embodiments of the present invention, the laser cutting marks are observed under 20 times coaxial light using a Keyence electronic magnifying glass to assist in determining the damage power threshold P2 of the glass.

[0055] Step S5, measuring the laser power fluctuation percentage M.

[0056] In the embodiment of the present invention, in step S6, the percentage of laser power fluctuation = (maximum power value - minimum power value) / average power value.

[0057] In some embodiments of the present invention, in step S6, the percentage of laser power fluctuation is measured at the penetration power threshold P1 of the film material. In some embodiments of the present invention, the specific measurement method of the percentage of laser power fluctuation is as follows: Set the laser power to the penetration power threshold P1 of the film material, cut the film-attached glass, the test time is 15 minutes, record the power value every 10 seconds, find the maximum and minimum power values, calculate the average power value, and calculate the percentage of power fluctuation according to the formula (maximum power value - minimum power value) / average power value.

[0058] In some embodiments of the present invention, after step S5, it further includes:

[0059] Determine the damage power threshold P3 of the coating. If multiple lasers are determined in step S1, select a suitable laser in combination with the damage power threshold P2 of the glass without the attached film material, the damage power threshold P3 of the coating, and the transmittance τ2 of the laser in the laser by the glass. The damage power threshold P3 of the coating is also used to confirm whether the subsequent determined cutting power is appropriate.

[0060] In the embodiment of the present invention, each power value is based on the average power value measured multiple times. For example, record the power value once every 10 seconds within 1 minute, and take the average value of all power values.

[0061] Step S6, measure the ortho-focus spot diameter Da of the focusing lens with different focal lengths.

[0062] The shape of the focusing lens after ortho-focus is similar to a funnel, and there is a small height in the middle depth of focus, which is easy to find the focal position; when defocused, the depth of focus is small and it is difficult to find the focal position. The debugging difficulty of ortho-focus is much less than that of defocus. In step S5, testing the ortho-focus spot diameter Da of the focusing lens with different focal lengths is for selecting a suitable focal length lens subsequently.

[0063] Step S7, determine the cutting method and cutting power according to the penetration power threshold P1 of the film material, the damage power threshold P2 of the glass, and the percentage of laser power fluctuation M under various defocusing methods:

[0064] If P1 < P2, cut once, and the range of the cutting power P is: P1 * (1 + M) < P < P2 * (1 - M);

[0065] If P1 ≥ P2, cut multiple times, the cutting power of the last time is Pz, and the cutting power of the previous n times is Pc1, where:

[0066] Pz < P2 * (1 - M);

[0067] The method for determining Pc1 is as follows:

[0068] Determine the number of cuts before the last one H is the total thickness of the film material, Hz is the cutting depth corresponding to the power Pz, and Hc is the cutting depth corresponding to the power, and τ1 is the transmittance of the film material to the laser in the laser

[0069] Determine the cutting depth Hn of the first n cuts, and determine the cutting power Pc1 of the first n cuts according to the cutting depth Hn of the first n cuts: the cutting depth of the first n cuts Taking Pc as the upper limit, draw a gradient curve of laser power and cutting depth downward, and find the laser power value Pc1 corresponding to the cutting depth Hn.

[0070] When P1 < P2, usually the film material is thinner, and the cutting power is between the upper limit of the penetration power of the film material and the lower limit of the damage power of the glass. The laser power reaching the glass = P * τ1 is usually much smaller than P2 * (1 - M). Even if all this power is absorbed by the glass, it will not damage the glass.

[0071] When P1 ≥ P2, usually the film material is thicker. To avoid damaging the glass, multiple cuts are required. The cutting power Pz of the last cut is less than the damage threshold of the glass, and the maximum cutting power of the film material Respectively determine the cutting depths Hz and Hc corresponding to the powers Pz and Pc through testing, calculate the number of cuts n before the last one, and round n up. Then calculate the cutting depth Hn of each cut in the first n cuts according to the calculated n value. Then draw a power gradient downward from Pc to find the laser power value Pc1 corresponding to the cutting depth Hn. With the parameters determined in the above manner, the cutting power for each time can ensure that the film material is penetrated without damaging the glass.

[0072] Step S8, select a focusing lens with an appropriate focal length and defocusing method, and use the determined cutting method and cutting power to cut the film material:

[0073] If only one cut is required, calculate the power interval Pa of the laser cutting power under various defocusing methods, and combine the size of the power interval Pa under each defocusing method, the debugging difficulty of various defocusing methods, the minimum qualified spot diameter Dmin, and the on-axis focal spot diameter Da to select a focusing lens with an appropriate focal length and defocusing method;

[0074] If multiple cuts are required, re-measure the corresponding minimum qualified spot diameter Dmin according to the maximum cutting power, and then select a focusing lens with an appropriate focal length and defocusing method based on the size of the power interval Pa corresponding to the maximum cutting power, the debugging difficulty of various defocusing methods, the minimum qualified spot diameter Dmin, and the on-axis focal spot diameter Da.

[0075] If the power range Pa under each defocus mode is not much different, select a focusing lens with a focal length whose positive focus spot diameter Da is smaller than and closest to the minimum standard spot diameter D.

[0076] In some embodiments of the present invention, in step S8, before cutting the film material using the determined cutting method and cutting power, the method further includes:

[0077] Change the beam expander magnification to fine-tune the spot diameter and adjust the laser cutting power according to the cutting effect. The specific method is: increase the beam expander magnification, use the film glass product to perform gradient verification on different beam expander magnifications, record the film material cutting power threshold P1, glass damage power threshold P2, spot diameter and cutting effect under different beam expander magnifications, select the beam expander magnification that meets the expected cutting effect, and determine the laser cutting power according to the film material cutting power threshold P1 and glass damage power threshold P2 corresponding to the beam expander magnification.

[0078] The above scheme is described in detail below using a specific embodiment. In this embodiment, the membrane material structure is as follows Figure 1 As shown, the finished glass structure with film and coating attached is as follows Figure 2 As shown. The film material includes a protective film, a PC layer, an adhesive layer, and a base film from top to bottom. The protective film, PC layer, and adhesive layer are attached to the upper surface of the finished glass. The overall thickness is 240um. The thickness of the finished glass is 1.2mm. The coating is a silk-screen ink layer with a thickness of 0.14um. The above film material except the base film is attached to the upper surface of the finished glass by machine thermal bonding. Select the laser and determine the laser parameters according to the following steps to cut off the excess film material:

[0079] Step S1, selecting a laser that causes the least damage to the coating according to the transmittance of the film material, glass, and coating to the laser.

[0080] The transmittance of the film materials, glass, and coatings used for verification to lasers of different wavelengths was tested. The following will refer to the film materials, glass, and coatings used for verification as verification film materials, verification glass, and verification coatings. The test results are as follows: the transmittance of the verification film materials to lasers of various wavelengths does not change much, about 16%; the transmittance of the verification glass to 355nm ultraviolet laser is 87%, the transmittance to 532nm green light is 89%, the transmittance to 1064nm optical fiber is 90%, and the transmittance to 10.6umCO2 laser is 0; the transmittance of the verification coating to lasers of various wavelengths is 0. Because the coating is thin and the transmittance to lasers of various wavelengths is 0, it is easy to absorb lasers and cause damage. In order to protect the coating from being damaged, a CO2 laser can be selected and the CO2 laser can be blocked by glass. The transmittance of the film material to CO2 laser is τ1≈16%, and the transmittance of the glass to CO2 is τ2≈0.

[0081] Step S2, select a short-focus focusing lens and an adjustable beam expander to cut the film material, determine the laser power threshold for cutting through the film material, and then determine the optimal laser frequency and the optimal cutting speed based on the laser power threshold, and set the optimal laser frequency and the optimal cutting speed for all subsequent steps.

[0082] In this embodiment, a focusing lens with a focal length of 50mm and a 0-5 times high-precision adjustable beam expander are used, and the beam expansion multiple is set to 2 times. The film material is first directly cut at 0.6W, and then a gradient test is performed with a power gradient of 0.05W, and the test is continued until 0.1W, and it is determined that the laser power threshold that just cuts through the film material is 0.25W. Then the power of the laser is set to 0.25W, and a frequency gradient verification is performed. Starting from 60KHz, a gradient test is performed with a frequency gradient of 5KHz, and the optimal laser frequency is determined to be 20KHz; then a cutting speed gradient test is performed, and the optimal cutting speed is determined to be 4mm / s.

[0083] Step S3, measuring the cutting power threshold P1 of the film material and the spot diameter corresponding to the cutting power threshold under various defocusing modes, and determining the minimum spot diameter Dmin for achieving the edge cutting effect.

[0084] Taking positive focus as the benchmark, positive and negative defocus gradients are verified in the range of -2, -1.5, -1.0, -0.5, 0, 0.5, 1.0, 1.5, and 2. The edge effect requirements are: no residue on the edge, no jaggedness under the naked eye, heat-affected area <0.05mm, no edge flipping, and bright edge <0.02mm under strong light. The verification results are as follows: the cutting power threshold of the positive focus film of the 50mm focusing lens is 0.25W, and the spot diameter is 78um; the cutting power threshold of the negative defocus -1.5 film is 0.31W, and the spot diameter is 140um; the cutting power threshold of the negative defocus -2 film is 0.35W, and the spot diameter is 190um; the cutting power threshold of the positive defocus 2 film is 0.37W, and the spot diameter is 206um. Through the measurement and analysis of the cutting edge with the naked eye and electron microscope, the smaller the spot diameter, the better the cutting edge effect; the spot diameter is the largest when the positive focus is 2, and the verified film cutting effect barely meets the standard. Therefore, it can be determined that the laser spot diameter ≤200um can achieve the effect, and Dmin=200um is taken.

[0085] Step S4, measuring the damage power threshold P2 of the glass without film material attached to the upper surface under various defocusing modes.

[0086] At the laser focus -2, -1.5, -1.0, -0.5, 0, 0.5, 1.0, 1.5, 2, the laser was used to directly hit the unfilmed glass, and the laser power was changed to 0.55W, 0.54W, ..., 0.25W. The power threshold of the laser damaging the glass at different focal positions was recorded, and its spot diameter was measured. The laser cutting marks were observed under the coaxial light of the Keyence electronic magnifier at 20 times to assist in determining the laser damage. The measurement results are as follows: the glass was verified to have a damage threshold of 0.35W and a spot diameter of 82um at the positive focus of the 50mm focusing lens; the damage threshold of 0.44W and a spot diameter of 148um at the negative defocus of -1.5; the damage threshold of 0.5W and a spot diameter of 201um at the negative defocus of -2; the damage threshold of 0.51W and a spot diameter of 212um at the positive defocus of 2.

[0087] Step S5, determining the damage power threshold P3 of the coating.

[0088] Use laser to directly draw straight lines on the coating, changing the laser power to 0.8W, 0.75W, ..., 0.1W, and then observe the light penetration of the laser-engraved straight lines on the back of the glass coating under strong light. The measurement results are: the verification coating is basically opaque when it is less than 0.55W, and no light penetration can be seen. The damage power threshold of the verification coating used in this example is greater than the damage threshold of the verification glass, and the transmittance of the verification glass to the laser is about 0. Therefore, when cutting, the coating under the glass will not be damaged while ensuring that the glass is not damaged.

[0089] Step S6, measuring the laser power fluctuation percentage M.

[0090] Because under the same conditions, the film material's cutting threshold is lower than the glass's damage threshold, the film material cutting power threshold is selected as the measurement standard. Specifically, the cutting parameters of the two extreme power thresholds at positive focus and positive defocus 2 are selected to test the power fluctuation value of the laser at these two powers. The power test time is 15 minutes, and the power value is recorded every 10 seconds. The measured power values ​​are represented by P1, P2,..., Pn. Arrange the recorded data, find the maximum and minimum power values, and calculate the power average value: PN = (P1 + P2 +... + Pn) / n; calculate the laser power fluctuation percentage: M = (maximum power value - minimum power value) / power average value PN. M = 8% at positive focus and M = 7.5% at positive defocus; thus, it is determined that the power fluctuation of the laser used is ≤8%.

[0091] Step S7, measuring the positive focus spot diameter Da of the focusing lenses with different focal lengths.

[0092] Replace focusing lenses with different focal lengths and measure the spot size at positive focus. The measurement results are: 50mm focal length lens spot diameter: 80um, 150mm focal length lens spot diameter: 161um, 200mm focal length lens spot diameter: 195um, 250mm focal length lens spot diameter: 242um.

[0093] Step S8, determining the cutting mode and cutting power according to the film material cutting through power threshold P1, the glass damage power threshold P2, and the laser power fluctuation percentage M under various defocusing modes.

[0094] In this embodiment, under the same conditions, the cutting power threshold P1 of the film material is smaller than the damage power threshold P2 of the glass, the damage power threshold P2 of the glass is smaller than the damage power threshold P3 of the coating, and the transmittance of the film material and the glass to CO2 laser is relatively low, so only one cutting is required, and the actually used cutting power P should be between the upper limit of the cutting power threshold and the lower limit of the glass damage threshold.

[0095] Step S9, calculate the power range Pa of the laser cutting power under various defocusing modes, and select the focusing lens with appropriate focal length and defocusing mode based on the size of the power range Pa under each defocusing mode, the debugging difficulty of various defocusing modes, the minimum standard spot diameter Dmin, and the positive focus spot diameter Da.

[0096] Calculate the power range under various defocusing modes. For example, when the focus position is -2, the cutting threshold of the film material is 0.35W, the damage threshold of the glass is 0.5W, the actual power is 0.38≤P≤0.46, and the power range is 0.08W; the power range at the focus position of -1.5 is 0.06W; the power range at the positive focus is 0.05W.

[0097] Because there are certain differences in laser equipment, in order to ensure the debugging space for mass production equipment, the larger the power range, the better; under different defocusing modes, the power range difference of this embodiment is small and can be ignored. Considering that the debugging of the focusing lens is much easier than the defocusing debugging, therefore, combined with the spot diameters of the focusing lenses of various focal lengths measured in step S7 and the minimum spot diameter of 200um determined in step S3, the focusing lens with a focal length of 200mm is selected, because its corresponding spot diameter is 195um, which is smaller than and closest to the minimum spot diameter, and the defocusing mode is selected as positive focus.

[0098] So far, the laser parameters that have been determined include: 200mm focal length, positive focus, optimal cutting frequency, optimal cutting speed, and cutting power.

[0099] Step S10, verifying the cutting effect of the focusing lens and the defocusing method selected in step S9, changing the beam expander magnification to fine-tune the spot diameter, and determining the laser cutting power according to the cutting effect, and using the determined laser cutting power to cut the film material.

[0100] In step S7, the measured spot diameter at 200 mm positive focus is 195 μm, which is between 190 μm at negative defocus of -2 and 206 μm at positive defocus of 2 in step S3. And the cutting-through threshold of the film material at positive defocus of 2 is 0.37 W. Therefore, after replacing the focusing lens with a focal length of 200 mm, the film material is cut using a power of 0.37 W, the cutting edge data is collected, and the judgment result is that the cutting effect meets the standard.

[0101] In steps S2 - S9, the beam expansion ratio is always set to 2, and the spot diameter at 200 mm positive focus is 195 μm, which is very close to the minimum spot diameter of 200 μm determined in step S3. Therefore, the spot diameter can be reduced by adjusting the beam expansion ratio to optimize the edge cutting effect. Specifically, change the beam expansion ratio, starting from 3.0 times, and perform gradient verification with a gradient of 0.2 times. Collect the cutting-through threshold of the film material, the glass damage threshold, the spot size, and the cutting effect, and record the data. Through the above data analysis, when the beam expander is 2.2 times, the cutting effect just meets the standard. To better ensure the cutting effect and avoid the upper and lower limits, select a slightly larger beam expansion ratio to determine the cutting parameters. Finally, the beam expander ratio of 2.3 times is selected. At this time, the spot diameter: 180 μm, the film material damage threshold: P1 = 0.34 W, the glass damage threshold P2 = 0.45 W, take the power fluctuation percentage M = 8%, the lower limit of the glass damage threshold = 0.45 * (1 - 8%) = 0.41 W, the upper limit of the film material cutting-through threshold = 0.34 * (1 + 8%) = 0.37 W; the selectable range of the cutting power: 0.37 W < P < 0.41 W. Select the power value within this range to perform full-penetration cutting on the excess film material. During the cutting process, the maximum power absorbed by the glass: 0.41 - 0.37 = 0.04 W, which is not enough to damage the glass and the coating.

[0102] The present invention has the following beneficial effects: The solution of the present invention selects the laser with the least damage to the coating according to the transmittance of the film material, glass, and coating to the laser; selects a short-focus focusing lens to determine the optimal laser frequency and the optimal cutting speed, measures the cutting-through threshold of the film material, the damage threshold of the glass, and the corresponding spot diameter under various defocusing methods, and determines the minimum qualified spot diameter according to the edge cutting effect; then determines the cutting times and the cutting power for each time according to the cutting-through threshold of the film material, the damage threshold of the glass, and the transmittance of the film material to the laser; then comprehensively considers the power range, the debugging difficulty, the minimum qualified spot diameter, and the positive-focus spot diameters of different focal lengths, and selects the focusing lens with a suitable focal length and the defocusing method; finally, cuts the film material using the determined cutting method and cutting power. The solution of the present invention can cut the film material on the surface of the glass finished product once or multiple times on the premise of ensuring that the glass and the coating are not damaged. This solution greatly enhances the feasibility of attaching the film material to the surface of the glass finished product by thermal lamination and then using laser to cut the excess film material, making it more suitable for large-scale production applications.

[0103] It should be noted that the solution of the present invention is also applicable to the cutting of film materials on the surface of other transparent materials except glass, and the cutting of film materials on the surface of glass or other transparent materials without coating on the lower surface.

[0104] The above are only specific implementations of the present invention, which cannot be used to limit the scope of the present invention. Equivalent changes made by ordinary technicians in this technical field based on this creation, as well as changes known to technicians in this field, should still fall within the scope of the present invention.

Claims

1. A method for laser cutting a film material on the surface of a finished glass product, wherein the finished glass product has a film material attached to its upper surface and a functional coating adhered to its lower surface, characterized in that: The method includes the following steps: Step S1: Select a laser that causes the least damage to the coating based on the transmittance of the film material, glass, and coating to the laser; Step S2: Select a short-focus focusing lens and an adjustable beam expander to cut the film material, determine the laser power threshold for cutting through the film material, and then determine the optimal laser frequency and the optimal cutting speed based on the laser power threshold. Set the optimal laser frequency and the optimal cutting speed for all subsequent steps; Step S3: Under various defocusing methods, measure the penetration power threshold P1 of the film material and the spot diameter corresponding to the penetration power threshold, and determine the minimum qualified spot diameter Dmin when the edge cutting effect meets the standard; Step S4: Under various defocusing methods, measure the damage power threshold P2 of the glass with no film material attached to its upper surface; Step S5: Measure the percentage M of the laser power fluctuation; Step S6: Measure the ortho-focus spot diameter Da of the focusing lens with different focal lengths; Step S7: Determine the cutting method and cutting power based on the penetration power threshold P1 of the film material, the damage power threshold P2 of the glass, and the percentage M of the laser power fluctuation under various defocusing methods: If P1 < P2, cut once, and the range of the cutting power P is: P1*(1 + M) < P < P2*(1 - M); If P1 ≥ P2, cut multiple times. The cutting power of the last time is Pz, and the cutting power of the previous n times is Pc1, where: Pz < P2*(1 - M); The method for determining Pc1 is: Determine the number of cuts before the last one H is the total thickness of the film, Hz is the cutting depth corresponding to the power Pz, and Hc is the power The corresponding cutting depth, τ1 is the transmittance of the film material to the laser in the laser; Determine the cutting depth Hn of the previous n times, and determine the cutting power Pc1 of the previous n times according to the cutting depth Hn of the previous n times: the cutting depth of the previous n times Draw a laser power and cutting depth gradient curve downward with Pc as the upper limit, and find the laser power value Pc1 corresponding to the cutting depth Hn; Step S8: Select a focusing lens with a suitable focal length and a defocusing method, and use the determined cutting method and cutting power to cut the film material: If only one cut is required, calculate the power interval Pa of the laser cutting power under various defocusing methods. Combine the sizes of the power intervals Pa under various defocusing methods, the debugging difficulties of various defocusing methods, the minimum qualified spot diameter Dmin, and the ortho-focus spot diameter Da, and select a focusing lens with a suitable focal length and a defocusing method; If multiple cuts are required, re-measure the corresponding minimum qualified spot diameter Dmin according to the maximum cutting power, and then select a focusing lens with a suitable focal length and a defocusing method based on the size of the power interval Pa corresponding to the maximum cutting power, the debugging difficulties of various defocusing methods, the minimum qualified spot diameter Dmin, and the ortho-focus spot diameter Da.

2. The method for laser cutting of a finished glass surface film material according to claim 1, characterized in that: In step S8, before using the determined cutting method and cutting power to cut the film material, it further includes: Changing the beam expander magnification to finely adjust the spot diameter and adjusting the laser cutting power according to the cutting effect.

3. The method for laser cutting of a finished glass surface film material according to claim 2, characterized in that: The specific method of changing the beam expander magnification to finely adjust the spot diameter and adjusting the laser cutting power according to the cutting effect is: increasing the beam expansion magnification of the beam expander, using a film-coated glass product to perform gradient verification for different beam expansion magnifications, recording the penetration power threshold P1 of the film material, the damage power threshold P2 of the glass, the spot diameter, and the cutting effect under different beam expander magnifications, selecting the beam expander magnification with the cutting effect meeting the expectations, and determining the laser cutting power according to the penetration power threshold P1 of the film material and the damage power threshold P2 of the glass corresponding to the beam expander magnification.

4. The method for laser cutting of a finished glass surface film material according to claim 1, characterized in that: In step S2, the focal length of the focusing lens is 50 mm, and the beam expansion factor of the beam expander is set to 2 times.

5. The method for laser cutting of a finished glass surface film material according to claim 1, characterized in that: In the step S5, the laser power fluctuation percentage = (maximum power value - minimum power value) / average power value.

6. The method for laser cutting of a finished glass surface film material according to claim 1, characterized in that: In the step S5, the laser power fluctuation percentage is measured at the film cutting power threshold value P1.

7. The method for laser cutting of a finished glass surface film material according to claim 1, characterized in that: In step S8, the method for selecting a focusing lens with a suitable focal length and a defocusing mode includes: if the power ranges Pa under each defocusing mode are not much different, selecting a focusing lens with a focal length whose positive focus spot diameter Da is smaller than and closest to the minimum qualified spot diameter Dmin.

8. The method for laser cutting of a finished glass surface film material according to claim 1, characterized in that: After step S5, the method further includes: Determine the damage power threshold P3 of the coating. If multiple lasers are determined in step S1, select a suitable laser based on the damage power threshold P2 of the glass without the film material attached, the damage power threshold P3 of the coating, and the transmittance τ2 of the glass to the laser in the laser.

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