A method of laser welding glass

Abstract

This invention discloses a method for laser welding glass, comprising the following steps: S100: wiping a first glass and a second glass with a lint-free cloth; S200: stacking the first glass and the second glass vertically; S300: adding purified water between the first glass and the second glass, wherein the amount of purified water added is determined according to the surface area of ​​the glass, and is 0.5 μl / cm². 2 ~1μl / cm 2 S400: Apply constant vertical pressure to the first and second glass sheets using a clamp to reduce the gap between them to less than 200 nm; S500: Remove the clamp and take out the first and second glass sheets, then weld them together using a laser. This invention allows for higher welding quality on ordinary commercial float glass sheets with greater efficiency, lower cost, and fewer limitations.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of laser welding, and relates to a method for laser welding glass. TECHNICAL BACKGROUND

[0002] Glass has good insulating properties, high transparency, strong chemical stability and good biocompatibility, and has a wide application prospect. In the fields of micro-electro-mechanical system (MEMS), aerospace, optical devices, biomedicine and the like, a single piece of glass often cannot meet the actual application requirements, and two or more pieces of glass need to be connected. With the rapid development of laser processing technology, the method for connecting multiple pieces of glass by using laser welding has gradually replaced traditional glass connection methods such as anodic bonding, brazing and adhesion. When two pieces of glass are welded by using a laser, the size of the gap between the two pieces of glass will have a significant impact on the welding quality. When the welding gap is too large, the welding quality will be poor or even the welding will fail. If the gap is to be reduced, the surface roughness and flatness of the glass have very high requirements, and sometimes custom-made instruments are needed, which has a great limitation on the shape and size of the welding area. Therefore, a method for achieving high welding quality on ordinary commercial glass sheets with higher efficiency, lower cost and fewer limitations is needed. SUMMARY

[0003] The present application provides a method for laser welding glass, and solves the technical problem of how to achieve high welding quality on ordinary commercial float glass sheets with higher efficiency, lower cost and fewer limitations.

[0004] The object of the present application can be achieved by the following technical solutions:

[0005] A method for laser welding glass, characterized in that it comprises the following steps:

[0006] S100: wiping the first glass 1 and the second glass 2 with a dust-free cloth;

[0007] S200: stacking the first glass 1 and the second glass 2;

[0008] S300: dropping pure water 3 between the first glass 1 and the second glass 3;

[0009] The amount of the dropped pure water is determined according to the surface area of the glass, and is 0.5 μl / cm 2 ~ 1 μl / cm 2 .

[0010] S400: applying a constant vertical pressure to the first glass 1 and the second glass 2 using a clamp,

[0011] narrowing the gap between the first glass 1 and the second glass 2 to less than 200nm;

[0012] S500: removing the clamp and taking out the first glass 1 and the second glass 2, and welding the first glass 1 and the second glass 2 using laser.

[0013] Preferably, in the above method of laser welding glass, the vertical pressure in step S400 ranges from 150N to 200N.

[0014] Preferably, in the above method of laser welding glass, the gap between the first glass 1 and the second glass 2 in step S400 includes pure water 3 and forms a liquid bridge, and the pressure difference Δp between the inside and outside of the liquid bridge, Δp≥0.32MPa.

[0015] Preferably, in the above method of laser welding glass, the vertical pressure in step S300 ranges from 150N to 200N.

[0016] Preferably, in the above method of laser welding glass, the duration of applying constant vertical pressure to the first glass 1 and the second glass 2 using the clamp in step S4300 is 4-5 minutes.

[0017] Preferably, in the above method of laser welding glass, the clamp body in step S400 is a pair of T-shaped metal blocks 4, and the contact surface of the first glass 1 and the second glass 2 is covered with a 5mm thick rubber layer 5.

[0018] Preferably, a layer of lint-free cloth 6 is attached to the rubber layer 5.

[0019] Preferably, in the above method of laser welding glass, the thickness of the first glass 1 and the second glass 2 ranges from 0.5mm to 5mm.

[0020] Preferably, in the above method of laser welding glass, the lint-free cloth in step 1 is alcohol cloth or acetone cloth.

[0021] Compared with the prior art, the method of the present application has the following beneficial effects: when there is a certain amount of water between the two glass sheets with a small gap, the water forms a liquid bridge, and after the external vertical pressure is removed, the pressure on the glass sheets generated by the liquid bridge can continue to maintain the gap between the two glass sheets in an optical contact state. Since the gap between the glasses in the optical contact area is extremely small, the water content in this area is also extremely small, which does not affect the final quality of laser welding. Therefore, it is possible to achieve higher welding quality on ordinary commercial float glass sheets with higher efficiency, lower cost and fewer limitations. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the pressure applied between the glasses in the embodiment of the present application;

[0023] Figure 2 is a schematic diagram of the curvature radius geometry of the liquid at the glass-liquid bridge interface in the embodiment of the present application;

[0024] Figure 3 is a schematic diagram of the change of the optical contact area with time in the embodiment of the present application;

[0025] Figure 4 is a schematic diagram of the structure of the clamp in the embodiment of the present application;

[0026] Figure 5 is a schematic diagram of the relationship between the optical contact state and the vertical pressure size and the holding time in the embodiment of the present application; DETAILED DESCRIPTION

[0027] In order to make the technical problems solved by the present application, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] In the description of the present application, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0029] The method for laser welding glass in the embodiment of the present application mainly includes the following steps S100 to S500.

[0030] Step S100: wiping the first glass 1 and the second glass 2 with a dust-free cloth.

[0031] In the step S100, the thickness of the first glass 1 and the second glass 2 is within 0.5-5mm, and the dust-free cloth can be alcohol cloth or acetone cloth.

[0032] Step S200: stacking the first glass 1 and the second glass 2.

[0033] Step S300: dropping pure water 3 between the first glass 1 and the second glass 2; a small amount of pure water is first dropped between the two glasses, and the water needs to fill the gap between the glasses as much as possible while being as little as possible to avoid interference of the excess water. Preferably, the amount of the dropped pure water is determined according to the surface area of the glass, which is 0.5μl / cm 2 ~1μl / cm 2 .

[0034] For two pieces of commercial float glass in natural stacked state, the gap between the glass sheets is generally about 3-5 μm.

[0035] When there is a certain amount of water between the two glass sheets with small gap, the water will form a liquid bridge. Due to the presence of surface tension, a pressure difference will be formed inside and outside the liquid bridge, which will form a certain pressure on the two glass sheets, as shown in the attached Figure 1 The size of the pressure difference Δp can be calculated as:

[0036]

[0037] Where γ is the surface tension coefficient of water, and r1 and r2 are the curvature radii of the liquid at the solid-liquid and gas-liquid interfaces, respectively. Since the glass sheets are flat, r1 is infinite. r2 is the curvature radius of the liquid at the interface between the liquid and gas on the side boundary of the liquid bridge, which can be converted by the geometric relationship as shown in the attached Figure 2 , as shown in the attached Figure 2 , the gap between the two glass sheets is 2d, and the contact angle between water and glass sheet is θ, then From which we can further calculate

[0038] Step S400: using a clamp to apply a constant vertical pressure to the first glass and the second glass, so that the gap between the first glass 1 and the second glass 2 is reduced to less than 200 nm.

[0039] When the gap between the two glass sheets is small, interference fringes will be produced due to the interference of light. The interference fringes will spread outward from the area with the smallest gap. In the visible light state, the innermost fringe of the interference fringes is produced by the purple light with the shortest wavelength in the visible light, and the shortest wavelength of the purple light is 400 nm. Therefore, the gap of the glass at the innermost purple fringe is 200 nm. When the gap is less than 200 nm, it has exceeded the minimum gap for the production of interference fringes by visible light, so it can be said that the area on the two glass sheets with a gap less than 200 nm has reached an optical contact state. In this optical contact area, using laser to weld the two glass sheets can obtain good welding quality. As described in step S300, the gap between the two pieces of commercial float glass in natural stacked state is generally about 3-5 μm. By applying vertical pressure, the gap can be reduced to 200 nm, but it is difficult to perform laser welding while maintaining the pressure, and there are great limitations on the shape and size of the glass and the welding area. Therefore, the patent uses a liquid bridge as a method to achieve and maintain large-area optical contact between the glass.

[0040] With the average gap of the optical contact area being 200 nm, the surface tension coefficient of pure water at 25°C is γ = 7.2 x 10-2 N / m, and the contact angle with the glass is θ = 25°, then Δp = 0.32 MPa. Therefore, in order to form optical contact, preferably, Δp ≥ 0.32 MPa, at this time, after the external vertical pressure is removed, the pressure on the glass sheet generated by the liquid bridge can continue to maintain the gap between the two glass sheets in the state of optical contact, and a large area of optical contact is achieved on the glass sheet, and there are obvious interference fringes in the non-optical contact area. This optical contact can be maintained for a long time, and the specific test results are shown in the attached Figure 3 At the moment when the external pressure is just removed, the proportion of the optical contact area is 65%, and after the external pressure is removed for 2 hours, the proportion of the optical contact area is still 50%.

[0041] In order to ensure that the external pressure can be uniformly applied to the glass surface, a clamp is used to apply a constant vertical pressure to the first glass 1 and the second glass 2. The clamp body is a pair of T-shaped metal blocks 4, the size of which is close to the size of the glass sheet. The vertical part of the T-shaped clamp is clamped by a press, and the horizontal part is in contact with the glass sheet to apply pressure to the glass sheet. In order to avoid damage caused by direct contact between the metal and the glass under a large pressure, a 5mm thick rubber layer 5 is covered on the surface of the T-shaped clamp in contact with the glass, and a layer of dust-free cloth 6 is attached on the rubber layer to avoid adhesion between the rubber and the glass under a large pressure. The schematic diagram of the clamp structure is shown in the attached Figure 4 .

[0042] The duration of applying a constant vertical pressure to the first glass 1 and the second glass 2 by the clamp is 4-5 minutes, and the size of the vertical pressure is 150-200N. Then the pressure is removed and the first glass 1 and the second glass 2 are taken out, and the optical contact is achieved. The specific experimental results are shown in the attached Figure 5 .

[0043] Step S500: removing the clamp and taking out the first glass 1 and the second glass 2, and using laser to weld the first glass 1 and the second glass 2.

[0044] By the method of the present application, a liquid bridge is formed between two glass sheets, the pressure is removed and the glass sheets are taken out, and the optical contact can be achieved. The method can achieve optical contact on ordinary commercial float glass sheets with higher efficiency, lower cost and fewer limitations. Since the gap between the glasses in the optical contact area is extremely small, the water content in this area is also extremely small, which will not affect the final quality of laser welding.

Claims

1. A method of laser welding glass, characterized by, The method comprises the following steps: S100: wiping the first glass (1) and the second glass (2) with a duster; S200: vertically stacking the first glass (1) and the second glass (2); S300: dripping pure water between the first glass (1) and the second glass (2), wherein the amount of pure water added is determined according to the surface area of the glass, being 0.5 ~1 ; S400: applying a constant vertical pressure to the first glass (1) and the second glass (2) by using a clamp, the vertical pressure in the step S400 ranges from 150N to 200N, reducing the gap between the first glass (1) and the second glass (2) to less than 200nm ; when the gap is less than 200nm, the minimum gap for visible light to generate interference fringes has been exceeded, thus the area on the two pieces of glass where the gap is less than 200nm reaches an optically contacting state, and the two pieces of glass are welded using a laser in this optically contacting area; in the step S400, the gap between the first glass (1) and the second glass (2) includes pure water (3) and forms a liquid bridge, and the pressure difference between the inside and outside of the liquid bridge , ; S500: removing the clamp and taking out the first glass (1) and the second glass (2), the pressure on the glass sheet generated by the liquid bridge continues to maintain the gap between the first glass (1) and the second glass (2) in an optical contact state, and the first glass (1) and the second glass (2) are welded by using a laser.

2. The method of laser welding glass of claim 1, wherein, The duration of applying the constant vertical pressure to the first glass (1) and the second glass (2) by using the clamp in the step S400 ranges from 4 minutes to 5 minutes.

3. The method of laser welding glass of claim 1, wherein, The clamp in the step S400 is a pair of T-shaped metal blocks (4), and a 5mm-thick rubber layer (5) is covered on the contact surface of the first glass and the second glass.

4. The method of laser welding glass of claim 3, wherein, A layer of duster (6) is pasted on the rubber layer (5).

5. The method of laser welding glass of claim 1, wherein, The thickness of the first glass (1) and the second glass (2) ranges from 0.5mm to 5mm.

6. The method of laser welding glass of claim 1, wherein, The duster in the step S100 is alcohol duster or acetone duster.

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