A method for laser cutting a surface film of a glass finished product

Abstract

The application discloses a kind of glass finished product surface film material laser cutting method, belong to laser cutting technical field.This scheme according to the transmittance of film material, glass, coating to laser selects laser;Select short focus focusing lens to determine laser frequency and cutting speed, measure the cutting penetration threshold of film material under various defocusing modes, the damage threshold of glass, according to edge cutting effect to determine minimum standard spot diameter;Then according to each threshold and the transmittance of film material to laser determines cutting frequency and the cutting power of each time;Again according to power interval, debugging difficulty, minimum standard spot diameter and other parameters select the focusing lens of appropriate focal length and defocusing mode.The scheme of the application can ensure that glass and coating are not damaged under the premise, the film material on the surface of glass finished product is cut once or multiple times, greatly enhances the feasibility of using laser to cut excess film material after film material is attached to the surface of glass finished product by heat bonding method, makes it more suitable for large-scale production application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser cutting, in particular to a glass finished product surface film material laser cutting method. BACKGROUND

[0002] The laser cutting film material is mainly divided into two ways of ablation cutting and melting cutting. Both methods use laser directly on the material, but the influence of laser on the lower layer of the film material may cause process damage. For the film product, two cutting methods are usually used in the market: semi-transparent cutting and full-transparent cutting. Semi-transparent cutting is mainly applied to label paper and other products, and obvious cutting marks are formed on the bottom film through laser cutting, and the film itself is not completely cut. Full-transparent cutting is often used for mobile phone film and other products, and the film material is completely cut by laser, and then attached to the target surface, such as mobile phone screen.

[0003] However, the above-mentioned traditional method of cutting first and then pasting film has some limitations, mainly reflected in the insufficient position accuracy of the film after pasting and the problem of easy air bubble, which usually cannot meet the requirements of high-quality products. Especially for 3D glass products, which have very high requirements on quality, these problems are particularly prominent. Therefore, a new film pasting method appears, that is, a film material slightly larger than the size of the glass product is first pasted to the surface of the glass product by heat bonding, and the air bubbles between the film material and the glass product are removed by vacuumizing during the pasting process, and then the excess film material on the edge of the glass product is removed by laser. However, the film material is usually a multi-layer composite structure as shown in Figure 1 According to the product quality requirements, the size of the film material needs to be slightly smaller than that of the glass product, and the edge cutting effect of the film material also has very high requirements. Some glass products also have functional coatings on the bottom surface, which requires the laser to cut through the film material exactly, but not to damage the glass and the coating, and the edge cutting effect of the film material needs to meet the requirements. How to select appropriate laser cutting parameters according to the characteristics of the film material, glass and coating to achieve the above cutting effect is a problem that needs to be solved at present. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a glass finished product surface film material laser cutting method for cutting the film material attached to the surface of the glass finished product by laser.

[0005] To achieve the above-mentioned purpose, the present application provides a glass finished product surface film material laser cutting method, the upper surface of the glass finished product is attached with a film material, and the lower surface is attached with a functional coating, the method comprising the following steps:

[0006] Step S1, selecting a laser with the least 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 optimal cutting speed based on the laser power threshold, and set the optimal laser frequency and optimal cutting speed for subsequent steps;

[0008] Step S3, measure the cutting-through power threshold P1 of the film material and the corresponding spot diameter under various defocusing modes, and determine the minimum standard spot diameter Dmin that meets the edge cutting effect standard;

[0009] Step S4, measure the damage power threshold P2 of the glass without the film material on the upper surface under various defocusing modes;

[0010] Step S5, measure the laser power fluctuation percentage M;

[0011] Step S6, measure the on-focus spot diameter Da of the focusing lens with different focal lengths;

[0012] Step S7, determine the cutting mode and cutting power according to the cutting-through 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 modes:

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

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

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

[0016] The determination method of Pc1 is:

[0017] Determine the number of times of cutting before the last time 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 corresponding to the power, and 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 Draw a laser power and cutting depth gradient curve with Pc as the upper limit, and 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 mode, and use the determined cutting mode and cutting power to cut the film material:

[0020] If only one cutting is needed, the power interval Pa of laser cutting power under various defocusing modes is calculated, and the focusing lens with appropriate focal length and defocusing mode is selected according to the size of the power interval Pa under various defocusing modes, the difficulty of adjusting various defocusing modes, the minimum standard spot diameter Dmin, and the on-focus spot diameter Da.

[0021] If multiple cutting is needed, the minimum standard spot diameter Dmin corresponding to the maximum cutting power is re-measured, and then the focusing lens with appropriate focal length and defocusing mode is selected according to the size of the power interval Pa corresponding to the maximum cutting power, the difficulty of adjusting various defocusing modes, the minimum standard spot diameter Dmin, and the on-focus spot diameter Da.

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

[0023] The expansion mirror multiple is changed to fine-tune the spot diameter, and the laser cutting power is adjusted according to the cutting effect.

[0024] Preferably, the specific method of changing the expansion mirror multiple to fine-tune the spot diameter and adjusting the laser cutting power according to the cutting effect is: increasing the expansion multiple of the expansion mirror, using the film glass product to do gradient verification for different expansion multiples, recording the cutting-through power threshold P1 of the film material, the damage power threshold P2 of the glass, the spot diameter, and the cutting effect under different expansion mirror multiples, selecting the expansion mirror multiple with the expected cutting effect, and determining the laser cutting power according to the cutting-through power threshold P1 of the film material and the damage power threshold P2 of the glass corresponding to the expansion mirror multiple.

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

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

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

[0028] Preferably, in step S8, the method of selecting the focusing lens with appropriate focal length and defocusing mode comprises: if the power interval Pa under various defocusing modes is not much different, selecting the focusing lens with focal length smaller than and closest to the minimum standard spot diameter Dmin.

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

[0030] determine the damage power threshold P3 of the coating, if multiple lasers are determined in the step S1, select a suitable laser in combination with the damage power threshold P2 of the glass without the film material, the damage power threshold P3 of the coating and the transmittance τ2 of the glass to the laser of the laser.

[0031] The present application has the following advantages: the scheme of the present application selects the laser with the minimum damage to the coating according to the transmittance of the film material, the glass and the coating to the laser; selects the short-focus focusing lens to determine the optimal laser frequency and the optimal cutting speed, measures the cutting penetration threshold of the film material, the damage threshold of the glass and the corresponding spot diameter in various defocusing modes, determines the minimum standard spot diameter according to the edge cutting effect; then determines the cutting times and the cutting power of each time according to the cutting penetration threshold of the film material, the damage threshold of the glass and the transmittance of the film material to the laser; further considers the power interval, the adjustment difficulty, the minimum standard spot diameter and the paraxial spot diameter of different focal lengths to select the focusing lens with a suitable focal length and the defocusing mode; finally cuts the film material using the determined cutting mode and cutting power. The scheme of the present application can cut the film material on the surface of the glass product for single or multiple times without damaging the glass and the coating. This scheme greatly enhances the feasibility of cutting the excess film material using laser after the film material is attached to the surface of the glass product by the thermal attachment method, and makes it more suitable for large-scale production application. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0033] Figure 1 It is a schematic diagram of the composite film material structure.

[0034] Figure 2 It is a schematic diagram of the glass product with film material and coating provided by the embodiment of the present application.

[0035] Figure 3 It is a schematic diagram of the glass product surface film material laser cutting method provided by the embodiment of the present application.

[0036] Figure 4 It is a schematic diagram of the laser defocusing principle provided by the embodiment of the present application.

[0037] Figure 5 It is a schematic diagram of the laser spot diameter measurement provided by the embodiment of the present application.

[0038] Figure 6 It is a schematic diagram of the laser damage threshold verification provided by the embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0040] The embodiments of the present application will be further described below with reference to the drawings of the specification. It should be understood that the described embodiments are only used for illustrating and explaining the present application, and are not used for limiting the present application.

[0041] The present application is suitable for removing the excess film material on the surface of a glass product. The upper surface of the glass product is attached with a film material, and the lower surface is adhered with a functional coating. Figure 2 As shown in the structural schematic diagram of the glass product with a film material and a coating provided by the embodiments of the present application. In some embodiments of the present application, the functional coating is an ink layer printed by silk screen.

[0042] As shown in the structural schematic diagram of the glass product with a film material and a coating provided by the embodiments of the present application. In some embodiments of the present application, the functional coating is an ink layer printed by silk screen. Figure 3 As shown in the structural schematic diagram of the glass product with a film material and a coating provided by the embodiments of the present application. In some embodiments of the present application, the functional coating is an ink layer printed by silk screen.

[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 transmittance of the coating to the laser of each waveband is low, the laser is easily absorbed to cause damage. In order to protect the coating from being damaged, a CO2 laser with low transmittance to glass can be selected.

[0045] If the transmittance of the coating to the laser of some wavebands is high, such as being able to withstand ultraviolet laser, green laser or other waveband laser, the corresponding waveband laser can be selected.

[0046] Step S2: Selecting a short-focus focusing lens and an adjustable beam expander to cut the film material, 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. The optimal laser frequency and the optimal cutting speed are set for all subsequent steps.

[0047] The purpose of the 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 focused spot, the smaller the focal depth, and the faster the spot changes when defocusing, which is beneficial to speed up the verification process. In some embodiments of the present application, in the step S2, the focal length of the focusing lens is 50 mm, and the expansion multiple of the beam expander is set to 2 times.

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

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

[0050] As shown in Figure 4 As shown in Figure 5 As shown in

[0051] In the embodiment of the present application, the edge cutting effect is evaluated according to whether it cuts through, smoothness, and the size of the heat-affected area, and the standard for meeting the standard is: no residue on the edge, no jaggedness under naked eye, heat-affected area < 0.05 mm, no edge lifting, and bright edge < 0.02 mm under strong light.

[0052] In the embodiment of the present application, the method for determining the minimum standard spot diameter D for the edge cutting effect to meet the standard is: judging whether the edge cutting effect meets the standard when the laser power is the cutting-through power threshold P1 of the film material in each defocusing mode, and selecting the minimum one of the laser spot diameters corresponding to the cutting-through power threshold P1 values of all the film materials that meet the standard as the minimum standard spot diameter D.

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

[0054] In the embodiment of the present application, the specific method for measuring the damage power threshold P2 of the glass without the film material attached to the upper surface is: directly cutting the glass without the film material attached to the upper surface with high power, and then making a power gradient until the laser power threshold for cutting the glass is found. As shown in Figure 6 As shown in

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

[0056] In the step S6, the laser power fluctuation percentage is calculated as (maximum power value-minimum power value) / average power value.

[0057] In some embodiments of the present application, the laser power fluctuation percentage is measured at the film cutting threshold P1. In some embodiments of the present application, the laser power fluctuation percentage is measured by setting the laser power to the film cutting threshold P1, cutting the film-coated glass, recording the power value every 10 seconds for 15 minutes, finding the maximum and minimum power values, calculating the average power value, and calculating the power fluctuation percentage according to the formula (maximum power value-minimum power value) / average power value.

[0058] In some embodiments of the present application, the step S5 is followed by:

[0059] In the step S1, if multiple lasers are determined, the damage threshold P3 of the coating layer is determined, and a suitable laser is selected according to the damage threshold P2 of the uncoated glass, the damage threshold P3 of the coating layer, and the transmittance τ2 of the glass to the laser light.

[0060] In some embodiments of the present application, each power value is the average of multiple measurements, for example, the power value is recorded every 10 seconds for 1 minute, and the average of all power values is taken.

[0061] In the step S6, the on-focus spot diameter Da of the focusing lens with different focal lengths is measured.

[0062] The on-focus shape of the focusing lens is similar to a funnel, with a small height in the middle focal depth, making it easy to find the focal point. When defocused, the focal depth is small, making it difficult to find the focal point. The on-focus adjustment is much easier than the defocus. In the step S5, the on-focus spot diameter Da of the focusing lens with different focal lengths is measured to select a suitable lens with a suitable focal length.

[0063] In the step S7, the cutting method and the cutting power are determined according to the film cutting threshold P1, the glass damage threshold P2, and the laser power fluctuation percentage M under various defocusing methods.

[0064] If P1

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

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

[0067] The determination method of Pc1 is:

[0068] Determination of the cutting times before the last time 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 Pc1, τ1 is the transmittance of the film material to the laser in the laser.

[0069] Determination of the cutting depth Hn of the previous n times, and determination of the cutting power Pc1 of the previous n times according to the cutting depth Hn of the previous n times: the cutting depth Hn of the previous n times Draw a laser power and cutting depth gradient curve with Pc as the upper limit to find the laser power value Pc1 corresponding to the cutting depth Hn.

[0070] When P1 < P2, the film material is usually thin, and the cutting power is between the upper limit of the film material's cutting-through power and the lower limit of the glass's damage power. The laser power reaching the glass = P*τ1 is usually much smaller than P2*(1-M), and even if all the power is absorbed by the glass, there is no damage to the glass.

[0071] When P1 ≥ P2, the film material is usually thick, and multiple cutting is needed to avoid damaging the glass. The cutting power Pz of the last time is less than the damage threshold of the glass, and the maximum cutting power of the film material Determine the cutting depth Hz and Hc corresponding to the power Pz and Pc respectively through testing, calculate the cutting times n before the last time, and round up n. Then calculate the cutting depth Hn of each time in the previous n times according to the calculated n value. Then draw a power gradient from Pc to find the laser power value Pc1 corresponding to the cutting depth Hn. Through the above method, the cutting power of each time can ensure cutting through the film material and not damaging the glass.

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

[0073] If only one cutting is needed, calculate the power interval Pa of the laser cutting power under various defocusing modes, combine the size of the power interval Pa under each defocusing mode, the debugging difficulty of various defocusing modes, the minimum standard spot diameter Dmin, and the on-focus spot diameter Da, and select a focusing lens with a suitable focal length and a defocusing mode;

[0074] If multiple cutting is needed, remeasure the minimum standard spot diameter Dmin corresponding to the maximum cutting power, and then select a focusing lens with a suitable focal length and a defocusing mode according to the size of the power interval Pa corresponding to the maximum cutting power, the debugging difficulty of various defocusing modes, the minimum standard spot diameter Dmin, and the on-focus spot diameter Da.

[0075] If the power intervals Pa in each defocus mode are not significantly different, the focusing lens with a focal length of the focus spot diameter Da smaller than and closest to the minimum standard focus spot diameter D is selected.

[0076] In some embodiments of the present application, the step S8 further comprises, before cutting the film material using the determined cutting mode and cutting power:

[0077] The expansion mirror magnification is changed to fine-tune the spot diameter, and the laser cutting power is adjusted according to the cutting effect. The specific method is: increasing the expansion magnification of the expansion mirror, using the film glass product to do gradient verification for different expansion magnifications, recording the cutting-through power threshold P1 of the film material, the damage power threshold P2 of the glass, the spot diameter and the cutting effect under different expansion mirror magnifications, selecting the expansion mirror magnification with the expected cutting effect, and determining the laser cutting power according to the cutting-through power threshold P1 of the film material and the damage power threshold P2 of the glass corresponding to the expansion mirror magnification.

[0078] The above scheme will be described in detail below with a specific embodiment. In this embodiment, the film material structure is as shown in Figure 1 The glass finished product structure attached with the film layer and the coating layer is as shown in Figure 2 The film material from top to bottom includes a protective film, a PC layer, an adhesive layer, and a bottom film, wherein the protective film, the PC layer, and the adhesive layer are attached to the upper surface of the glass finished product, the total thickness is 240 um, the thickness of the glass finished product is 1.2 mm, and the coating layer is a silk screen ink layer with a thickness of 0.14 um. The above-mentioned film material except the bottom film is attached to the upper surface of the glass finished product by machine hot sticking, and the laser and the laser parameters are selected and determined according to the following steps to cut off the excess film material:

[0079] Step S1: selecting the laser with the smallest damage to the coating layer according to the transmittance of the film material, glass, and coating layer to laser.

[0080] The transmittance of the film material, glass, and coating layer to different waveband lasers is tested and verified. The film material, glass, and coating layer used for verification are referred to as verification film material, verification glass, and verification coating layer, respectively, and the test results are as follows: the transmittance of the verification film material to each waveband laser changes little, about 16%; the transmittance of the verification glass to 355 nm ultraviolet laser is 87%, to 532 nm green light is 89%, to 1064 nm fiber is 90%, and to 10.6 um CO2 laser is 0; and the transmittance of the verification coating layer to each waveband laser is 0. Because the coating layer is thin and has a transmittance of 0 to each waveband laser, it is easy to absorb laser and cause damage. In order to protect the coating layer from being damaged, a CO2 laser can be selected to block the CO2 laser with the glass. The transmittance of the film material to the CO2 laser is τ1≈16%, and the transmittance of the glass to the CO2 laser 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 optimal cutting speed based on the laser power threshold. The optimal laser frequency and optimal cutting speed are set for all subsequent steps.

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

[0083] Step S3, measure the cutting-through power threshold P1 of the film material and the corresponding spot diameter under various defocusing modes, and determine the minimum qualified spot diameter Dmin that meets the edge cutting effect standard.

[0084] Based on the positive focus, gradient verification is performed in the range of -2, -1.5, -1.0, -0.5, 0, 0.5, 1.0, 1.5, and 2, and the edge effect requirements are: no residue on the edge, no sawtooth under the naked eye, heat affected zone <0.05 mm, no edge lifting, and bright edge <0.02 mm under strong light. The verification results are as follows: the cutting-through power threshold of the film material with a 50 mm focusing lens is 0.25 W, and the spot diameter is 78 um; the cutting-through power threshold of the film material with a negative defocus of -1.5 is 0.31 W, and the spot diameter is 140 um; the cutting-through power threshold of the film material with a negative defocus of -2 is 0.35 W, and the spot diameter is 190 um; the cutting-through power threshold of the film material with a positive defocus of 2 is 0.37 W, and the spot diameter is 206 um. Through naked eye and electron microscope measurement and analysis of the cutting edge, the smaller the spot diameter, the better the cutting edge effect; the spot diameter is largest at positive focus 2, and the verification of the film material cutting effect is barely qualified, so it can be determined that the laser spot diameter ≤200 um can achieve the effect standard, and Dmin=200 um.

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

[0086] The laser is directly used on the uncoated glass at the positions of -2, -1.5, -1.0, -0.5, 0, 0.5, 1.0, 1.5, and 2 of the laser focal point, and the laser power is changed to 0.55 W, 0.54 W,..., and 0.25 W. The power threshold of the laser cutting glass at different focal point positions is recorded, and the spot diameter is measured. The laser cutting trace is observed by the Keen Eis electronic magnifying glass with 20 times of coaxial light to assist in determining the laser damage. The measurement results are as follows: the damage threshold of the verification glass is 0.35 W at the positive focal point of the 50 mm focusing lens, the spot diameter is 82 um, the damage threshold is 0.44 W at the negative focal point of -1.5, the spot diameter is 148 um, the damage threshold is 0.5 W at the negative focal point of -2, the spot diameter is 201 um, and the damage threshold is 0.51 W at the positive focal point of 2, and the spot diameter is 212 um.

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

[0088] The laser is directly used on the coating, and the laser power is changed to 0.8 W, 0.75 W,..., and 0.1 W to cut a straight line on the coating. Then, the light penetration condition of the laser cutting straight line on the back coating of the glass is observed under strong light. The measurement results are as follows: the coating is basically not transparent to light when the laser power is less than 0.55 W, and the light penetration condition cannot be observed. The damage power threshold of the verification coating used in the present 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 under the condition that the glass is not damaged.

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

[0090] Because the cutting penetration threshold of the film material is lower than the damage threshold of the glass under the same conditions, the cutting penetration power threshold of the film material is selected as the measurement standard. Specifically, the cutting parameters of the two extreme power thresholds at the positive focal point and the positive focal point of 2 are selected, and the power fluctuation value of the laser at the two powers is tested. The power value is recorded every 10 seconds for 15 minutes, and is represented by P1, P2,..., and Pn. The recorded data is sorted out to find the maximum and minimum power values, and the average power value PN is calculated: PN=(P1+P2+...+Pn) / n. The power fluctuation percentage M is calculated: M=(maximum power value-minimum power value) / average power value PN. M=8% at the positive focal point, and M=7.5% at the positive focal point; it is determined that the power fluctuation of the used laser is ≤8%.

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

[0092] Replace the focusing lens with different focal lengths, measure the spot size at the focal length, and 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, determine the cutting mode and cutting power according to the cutting-through 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 modes.

[0094] In this embodiment, under the same conditions, the cutting-through 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 the CO2 laser is low, so only one cutting is needed. The actual cutting power P should be between the upper limit of the cutting-through threshold and the lower limit of the glass damage threshold.

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

[0096] Calculate the power interval under various defocusing modes, for example, when the focal point position is -2, the cutting-through 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 interval is 0.08W; when the focal point position is -1.5, the power interval is 0.06W; and when the focal point is at the focal length, the power interval is 0.05W.

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

[0098] At this point, the laser parameters that have been determined include: 200mm focal length, focal length, optimal cutting frequency, optimal cutting speed, and cutting power.

[0099] Step S10, verify the cutting effect of the focusing lens and defocusing mode selected in step S9, change the expansion mirror multiple to fine-tune the spot diameter, and determine the laser cutting power according to the cutting effect. The film material is cut using the determined laser cutting power.

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

[0101] In steps S2-S9, the beam expansion magnification is always set to 2, and the spot diameter at 200mm positive focus is 195um, which is very close to the minimum spot diameter of 200um determined in step S3. Therefore, the spot diameter can be reduced and the edge cutting effect can be optimized by adjusting the beam expansion magnification. Specifically, the beam expansion magnification is changed, starting from 3.0 times, and a gradient verification is performed with a gradient of 0.2 times. The film material cutting threshold, glass damage threshold, spot size and cutting effect are collected, and the data is recorded. Through the above data analysis, when the beam expander is 2.2 times, the cutting effect just meets the standard. In order to better ensure the cutting effect, avoid the upper and lower limits, select a slightly larger beam expansion magnification, and determine the cutting parameters. Finally, a beam expander magnification of 2.3 times is selected. At this time, the spot diameter is 180 μm, the film damage threshold is P1 = 0.34 W, the glass damage threshold is P2 = 0.45 W, the power fluctuation percentage M = 8%, the lower limit of the glass damage threshold is 0.45 * (1-8%) = 0.41 W, and the upper limit of the film cutting threshold is 0.34 * (1 + 8%) = 0.37 W. The optional cutting power range is 0.37 W. <P<0.41W。选择该范围内的功率值,对多余的膜材进行全透切割。切割过程中,玻璃吸收的最大功率:0.41-0.37=0.04W,不足以损伤玻璃及涂层。

[0102] The present invention has the following beneficial effects: the solution of the present invention selects a laser that causes minimal damage to the coating based on 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 optimal cutting speed, measures the film material's cutting-through threshold, the glass's damage threshold, and the corresponding spot diameter under various defocusing methods, and determines the minimum qualified spot diameter based on the edge cutting effect; then determines the number of cuts and the cutting power for each cut based on the film material's cutting-through 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 qualified spot diameter, and the positive focus spot diameter at different focal lengths, selects a focusing lens with a suitable focal length and defocusing method; finally, uses the determined cutting method and cutting power to cut the film material. The solution of the present invention can perform single or multiple cuts on the film material on the surface of the finished glass product, while ensuring that the glass and coating are not damaged. This solution 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.

[0103] It should be noted that the present application is also applicable to the cutting of film materials on the surface of other transparent materials other than 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 merely provides the specific implementation of the present application, and cannot be used to limit the scope of the present application. The equivalent changes made by those skilled in the art based on the present application, and the changes well known to those skilled in the art, should still fall within the scope of the present application.

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 modes, 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 for which the edge cutting effect meets the standard. Step S4: Under various defocusing modes, 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 laser power fluctuation. Step S6: Measure the on-axis 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 laser power fluctuation under various defocusing modes: 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 material, 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: 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 an appropriate focal length and a defocusing mode, 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 modes, and combine the sizes of the power intervals Pa under various defocusing modes, the debugging difficulties of various defocusing modes, the minimum qualified spot diameter Dmin, and the on-axis spot diameter Da to select a focusing lens with an appropriate focal length and a defocusing mode; 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 a defocusing mode based on the size of the power interval Pa corresponding to the maximum cutting power, the debugging difficulties of various defocusing modes, the minimum qualified spot diameter Dmin, and the on-axis spot diameter Da.

2. The method for laser cutting a finished glass surface film 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 laser cutting method for the surface film of a finished glass product 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: Increase the beam expander magnification, use the film-coated glass product to perform gradient verification for different beam expander magnifications, record 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, select the beam expander magnification with the cutting effect meeting the expectations, and determine the laser cutting power according to the penetration power threshold P1 of the film material and the damage power threshold P2 corresponding to the beam expander magnification.

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

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

7. The method for laser cutting a film material on the surface of a finished glass product according to claim 1, characterized in that: In step S8, the method of 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 a film material on the surface of a finished glass product 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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