Enhanced sealing large-spot laser welding method for plastic film part

Abstract

The invention relates to the technical field of laser processing and material connection, and discloses a plastic film plastic part reinforced sealing large-spot laser welding method which comprises the following steps: step 1, continuous bosses and grooves are correspondingly arranged on an upper frame and a lower frame of a plastic frame respectively, can be in various shapes and extend around an upper plastic frame and a lower plastic frame for one circle, and the bosses and the grooves are formed in the upper frame and the lower frame of the plastic frame respectively; the boss is divided into a welding area and a sealing area by taking the bottom of the inclined surface of the boss as a boundary; secondly, sealant is smeared on the upper plastic frame body and the lower plastic frame body respectively; and 3, placing the plastic film on the lower frame of the plastic frame, wherein the edge of the plastic film coincides with the boundary of the welding area and the sealing area. According to the invention, the two mutually welded plastic parts are divided into the sealing area and the welding area by taking the bottom of the inclined surface as the boundary, the sealing area is sealed by the sealant, and the welding area is quickly welded by adopting large-size focused spot laser, so that the problems of air tightness and firmness of the plastic film and the plastic frame are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser processing and material connection, in particular to a large-spot laser welding method for enhancing the sealing of plastic films and plastic parts. Background Art

[0002] In industrial applications, a large number of films and plastic products need to be bonded and sealed. Many of these films and plastics have significantly different product properties, making them incompatible. For example, the film may have a high melting point while the plastic has a low melting point, or the film may not be a thermoplastic while the plastic is a thermoplastic. These plastics and film materials cannot be welded or fused together. Although these plastic and film materials cannot be welded or fused together, this does not affect the weld strength during laser welding.

[0003] However, sealant can vaporize, volatilize, or carbonize under the action of lasers, reducing the strength of the seal. Therefore, the present invention proposes a large-spot laser welding method for enhanced sealing, which solves the airtightness and firmness issues between film materials and plastic products. Summary of the Invention

[0004] The purpose of the present invention is to provide a large-spot laser welding method for enhancing the sealing of plastic films and plastic parts, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: a large-spot laser welding method for enhancing the sealing of plastic film and plastic parts, comprising the following steps: Step 1: Continuous bosses and grooves are provided on the upper and lower plastic frames respectively. The bosses can be of various shapes and extend around the upper and lower plastic frames. The bottom of the bosses' slope is used as the boundary to divide the welding area and the sealing area. Step 2: Apply sealant on the upper and lower plastic frames respectively; Step 3: Place the plastic film on the lower plastic frame, with the edge of the plastic film aligning with the boundary line between the welding area and the sealing area. Then place the upper plastic frame, press the two plastic frames together, and press the four sides of the plastic film between the boss and the groove. Step 4: Use a large-focus laser to weld the welding area of ​​the two plastic frames. In order to improve welding efficiency, the welding spot diameter is usually greater than 10 mm.

[0006] Preferably, in step 2, if the degree of the boundary angle is less than 45 degrees, the sealing area and the sealant coating are 3 mm away from the boundary line between the welding area and the sealing area, that is, the sealant coating is 3 mm away from the welding area; if the degree of the boundary angle is greater than or equal to 45 degrees, the sealing area and the sealant coating are 2 mm away from the boundary line between the welding area and the sealing area, that is, the sealant coating is 2 mm away from the welding area. Further explanation: sealant is an industrial adhesive that will produce gasification, volatilization, or carbonization effects under the action of laser, reducing the strength of the seal. Applying the glue on the bevel a certain distance away from the welding area, as specified in the distance rule in step 2 above, ensures both sealing strength and welding strength.

[0007] Preferably, in step 2, the boundary angle is generally required to be greater than 30 degrees.

[0008] Preferably, during step 4, the welding range should extend 2 mm beyond the weld boundary line. Because there is an inclined surface between the welding area and the sealing area, the thermal effect of the laser during welding occurs only on the flat surface, and the inclined surface on the sealing area side is not affected by the laser. This ensures that the sealant and the plastic part are not welded, and after welding, the plastic film and the plastic frame are firmly connected.

[0009] Preferably, in step 4, a distance of 2-3 mm is left on the inclined surface 5 without being coated with sealant.

[0010] The present invention provides a large-spot laser welding method for enhancing the sealing of plastic films and plastic parts. It has the following beneficial effects: (1) The present invention divides two mutually welded plastic parts into a sealing area and a welding area with the bottom of the inclined surface as the boundary. The sealing area is sealed with sealant, and the welding area is quickly welded with a large-size focused spot laser, thereby solving the airtightness and firmness problems of the plastic film and the plastic frame.

[0011] (2) The present invention successfully solves the welding problem of high-melting-point film and low-melting-point plastic frame (or non-thermoplastic material) through laser energy field reconstruction technology. When the plastic film is a high-melting-point material, the large-spot laser directly melts the low-melting-point plastic frame to form a welding layer; when the plastic film is a low-melting-point material, it melts under heat and forms a mechanical interlocking structure with the high-melting-point plastic frame. This adaptive welding mechanism ensures that regardless of the difference in the melting points of the materials, a welding strength of ≥10N / cm can be achieved, while ensuring that the plastic film completely covers the sealing area, avoiding the problem of cold welding or leakage caused by material incompatibility in traditional welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the sealing area; Figure 2 Schematic diagram of boss and groove; Figure 3 It is a schematic diagram of the front view of the boundary between the sealing area and the welding area; Figure 4 It is a schematic side view of the boundary between the sealing area and the welding area; Figure 5 Schematic diagram of the bevel angle between the sealing area and the welding area; Figure 6 Schematic diagram of the bevel angle and the distance of the glue from the boundary; Figure 7 Schematic diagram of large laser spot welding; Figure 8 This is an example of a laser-processed part by Dinai. In the figure: plastic frame upper frame 1, plastic frame lower frame 2, sealant coating 3, plastic film 4, bevel 5, welding area 6, sealing area 7, boundary corner 8, distance between sealant and dividing line 9, welding spot 10, distance between welding spot and dividing line 11, and dividing line between welding area and sealing area 12. DETAILED DESCRIPTION

[0013] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts are within the scope of protection of the present invention.

[0014] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention.

[0015] A preferred embodiment of the large spot laser welding method for enhancing the sealing of plastic film and plastic parts provided by the present invention is as follows: Figure 1-8 As shown: A large spot laser welding method for enhancing the sealing of plastic film parts includes the following steps: Step 1: Continuous bosses and grooves are provided on the upper plastic frame 1 and the lower plastic frame 2, respectively. The bosses and grooves can be of various shapes and extend around the upper and lower plastic frames. The bottom of the boss's slope 5 is used as the boundary to divide the welding area 6 and the sealing area 7. Step 2: Apply sealant to the upper plastic frame 1 and the lower plastic frame 2 respectively. If the degree of the boundary angle 8 is less than 45 degrees, the sealing area 7 and the sealant coating 3 are 3 mm away from the boundary line 12 between the welding area and the sealing area, that is, the sealant coating 3 is 3 mm away from the welding area. If the degree of the boundary angle 8 is greater than or equal to 45 degrees, the sealing area 7 and the sealant coating 3 are 122 mm away from the boundary line 12 between the welding area and the sealing area, that is, the sealant coating 3 is 2 mm away from the welding area. The boundary angle 8 is generally required to be greater than 30 degrees. Step 3: Place the plastic film 4 on the lower plastic frame 2, with the edge of the plastic film 4 coinciding with the boundary line 12 between the welding area and the sealing area. Then place the upper plastic frame 1, and press the two plastic frames against each other so that the four sides of the plastic film 4 are pressed between the boss and the groove. Step 4: Use a large-focus laser to weld the welding area 6 of the two plastic frames. In order to improve welding efficiency, the welding spot 10 is usually larger than 10 mm in diameter. During welding, the welding range should exceed the welding boundary line by 2 mm. Since there is a bevel 5 between the welding area 6 and the sealing area 7, the thermal effect of the laser only appears on the plane during welding, and the bevel 5 on the sealing area 7 side is not affected by the laser. The bevel 5 is kept 2-3 mm away from being coated with sealant to prevent heat diffusion during laser welding from affecting the sealant.

[0016] If the plastic film 4 is made of a high melting point material and the plastic frame upper frame 1 and the plastic frame lower frame 2 are made of a low melting point material, welding will not be affected; if the plastic film 4 is made of a low melting point material and the plastic frame upper frame 1 and the plastic frame lower frame 2 are made of a high melting point material, the plastic film 4 will be affected by the thermal effect during laser welding, and a length of about 1-2 mm will melt. The melted plastic film 4 will be welded together with the subsequently melted plastic frame upper frame 1 and the plastic frame lower frame 2, without affecting the sealing effect and the welding effect, so the plastic film 4 covers the entire sealing area 7.

[0017] Ensure that there is no welding between the sealant coating 3 and the plastic frame upper frame 1 and the plastic frame lower frame 2, and after welding is completed, achieve airtightness and firmness between the plastic film 4 and the plastic frame.

[0018] Combine Figure 8 Taking this product as an example, the perfluorosulfonic acid membrane is placed between two perfluorosulfonic acid membrane frames. A concave-convex fit is provided on the two butt-welded perfluorosulfonic acid membrane frames, and sealant is applied to the sealing area. Then, the two perfluorosulfonic acid membrane frames are directly welded together. During welding, the sealant is protected from the heat of the laser. This structure overturns existing traditional practices and fundamentally solves the airtightness and robustness issues of the perfluorosulfonic acid membrane frames. The structure of the present invention can also be used in sealing between metals and thin films, similarly achieving excellent airtightness and robustness.

[0019] In summary, by physically isolating the welding area from the sealing area (bevel design + precise positioning of the sealant coating) and utilizing the planar heating characteristics of a large-spot laser, the present invention completely eliminates the negative impact of laser thermal effects on the sealant. Actual measurements show that: The carbonization rate of sealant is reduced from 45% of the traditional process to below 0.8%; The sealing interface shear strength reaches 2.5MPa (industry standard 0.8MPa); Helium leakage rate <1×10⁻ 8 Pa·m³ / s (traditional technology>5×10⁻ 6Pa·m³ / s).

[0020] This design is particularly suitable for precision scenarios that are sensitive to heat, such as perfluorosulfonic acid membranes. In application verification in the fuel cell field, the airtightness life of the membrane electrode assembly exceeded 10,000 hours, which is 4 times higher than that of traditional processes.

[0021] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0022] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A large-spot laser welding method for enhancing the sealing of plastic films and plastic parts, characterized by: The following steps are involved: Step 1: Continuous bosses and grooves are provided on the upper plastic frame (1) and the lower plastic frame (2), respectively. The bosses and grooves can be of various shapes and extend around the upper and lower plastic frames. The bottom of the boss slope (5) is used as the boundary to divide the welding area (6) and the sealing area (7). Step 2: Apply sealant to the upper plastic frame (1) and the lower plastic frame (2); Step 3: Place the plastic film (4) on the lower plastic frame (2), with the edge of the plastic film (4) coinciding with the boundary line (12) between the welding area and the sealing area, and then place the upper plastic frame (1), pressing the two plastic frames against each other so that the four sides of the plastic film (4) are pressed between the boss and the groove; Step 4: Use a large-focus laser to weld the welding area (6) of the two plastic frames. In order to improve welding efficiency, the diameter of the welding spot (10) is usually greater than 10 mm.

2. The large-spot laser welding method for reinforced sealing of plastic films and plastic parts according to claim 1, characterized in that: In step 2, if the degree of the boundary angle (8) is less than 45 degrees, the sealing area (7) and the sealant coating (3) are 3 mm away from the boundary line (12) between the welding area and the sealing area, that is, the sealant coating (3) is 3 mm away from the welding area; if the degree of the boundary angle (8) is greater than or equal to 45 degrees, the sealing area (7) and the sealant coating (3) are 2 mm away from the boundary line (12) between the welding area and the sealing area, that is, the sealant coating (3) is 2 mm away from the welding area.

3. The large-spot laser welding method for reinforced sealing of plastic films and plastic parts according to claim 1, characterized in that: In step 2, the boundary angle (8) is usually required to be greater than 30 degrees.

4. The large-spot laser welding method for enhancing the sealing of plastic films and plastic parts according to claim 1, characterized in that: In step 4, during welding, the welding range should exceed the welding boundary line by 2 mm. Since there is a bevel (5) between the welding area (6) and the sealing area (7), the thermal effect of the laser only appears on the plane during welding, and the bevel (5) on the sealing area (7) side is not affected by the laser.

5. The large-spot laser welding method for enhancing the sealing of plastic films and plastic parts according to claim 1, characterized in that: In step 4, a distance of 2-3 mm is left on the inclined surface (5) without being coated with sealant.

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