Transparent workpiece laser welding device and method

Abstract

The invention provides a laser welding device and method for a transparent workpiece, and the method comprises the steps: adjusting a laser spot to be flat-topped light and shortening the laser focal depth when the transparent workpiece with two layers of transparent materials is welded by laser, so that the two layers of transparent materials absorb laser energy. The transparent workpiece can be welded without adding an absorbent.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding of transparent workpieces, and particularly relates to a laser welding device and method for transparent workpieces. Background Art

[0002] Plastic is a kind of high molecular organic compound, with excellent properties such as light weight, high specific strength, and corrosion resistance. After nearly a century of development, plastic has become one of the important basic materials equivalent to steel, cement, and wood. Plastic plays an increasingly important role in the fields of optics, medical devices, food, aerospace, agriculture, and packaging. To meet diverse needs, more and more plastic parts cannot be produced by injection molding, and the secondary connection process has become a key technology for plastic part production.

[0003] At present, the secondary connection processes of plastic parts mainly include mechanical connection, adhesive connection, and welding. Although mechanical connection methods (such as bolts and rivets) can obtain relatively high connection strength, mechanical parts will increase the weight of plastic parts. The adhesive connection has problems such as low efficiency, low connection strength, and easy aging. The welding methods of plastic parts mainly include hot melt welding, friction welding, ultrasonic welding, and laser welding. The hot melt and ultrasonic welding of plastics are not environmentally friendly. More specifically, toxic or pungent gases will be generated during the hot melt welding process, and ultrasonic welding and friction welding will generate sharp noises and relatively large welding stresses. In addition, hot melt welding, friction welding, and ultrasonic welding are not suitable for complex or precision plastic parts. Laser welding is a plastic part welding technology that has developed rapidly in recent years, with characteristics such as high welding strength, fast welding speed, high precision, low welding stress, and strong adaptability to space curves.

[0004] Traditional laser plastic welding requires the upper layer material to be light-transmissive and the lower layer material to be light-absorbing. Only by melting the upper and lower layer materials through heat absorption conduction of the lower layer can they be welded together. With the development of technology and the breakthrough of microfluidic technology, there are higher requirements for the light transmittance and cleanliness of materials. Therefore, materials are increasingly inclined to transparent materials. However, limited by the traditional laser process, if two pieces of the same transparent material need to be welded, an absorbent material needs to be added for welding. However, the addition of the absorbent will affect the light transmittance, cleanliness, and welding efficiency, which has an adverse effect on the subsequent detection of microfluidics. Therefore, it is necessary to develop a laser welding device and method for transparent workpieces that can weld transparent workpieces without adding absorbents. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser welding device and method for transparent workpieces to solve the problem of low efficiency of the existing laser welding devices and methods for transparent workpieces.

[0006] To solve the above technical problems, the present invention provides a method for laser welding of transparent workpieces, comprising: when welding a transparent workpiece having two layers of transparent materials by using a laser, adjusting the laser spot to a flat-top beam and shortening the laser focal depth so that both layers of transparent materials absorb laser energy.

[0007] Optionally, place the transparent workpiece having two layers of transparent materials on a carrier plate, and place the carrier plate in the welding area, and use a constant-temperature heating device to perform constant-temperature heating on the welding area.

[0008] Optionally, control the temperature of the welding area at 45 - 55 °C.

[0009] Optionally, set the area of the carrier plate corresponding to the welding track of the transparent workpiece as a reflective mirror surface.

[0010] Optionally, place the carrier plate with the transparent workpiece in the welding area, and the welding area vacuum-adsorbs the transparent workpiece through the carrier plate, and the vacuum adsorption points of the transparent workpiece are located within the circle of the welding track.

[0011] Optionally, the wavelength of the laser is 1720 nm to 1940 nm.

[0012] Optionally, shape the laser through a spot shaping component and an adjustable collimation component to obtain a flat-top beam, and the focal depth can weld the upper transparent material and the lower transparent material of the transparent workpiece.

[0013] Optionally, the welding speed of the laser is 25 - 30 mm / s.

[0014] The present invention also provides a laser welding device for transparent workpieces, comprising a laser welder, the laser welder includes a galvanometer, an adjustable collimation component, a spot shaping component and a lens component, the laser sequentially passes through the galvanometer, the spot shaping component, the adjustable collimation component and the lens component, the spot shaping component and the adjustable collimation component are used to adjust the Gaussian beam to a flat-top beam, and the adjustable collimation component is also used to adjust the focal depth of the laser.

[0015] Optionally, it further includes a stage, the stage includes a heating base and a carrier plate for welding the transparent workpiece, a constant-temperature heating device is arranged in the heating base, and the carrier plate is fitted and installed on the welding area of the heating base.

[0016] The laser welding device and method for transparent workpieces provided by the present invention have the following beneficial effects:

[0017] First of all, by adjusting the laser spot shaping and the focal depth, the upper and lower layers of transparent workpieces can absorb the laser simultaneously, so as to realize the welding of the transparent workpiece.

[0018] Secondly, when placing a transparent workpiece with two layers of transparent materials on a carrier plate and positioning the carrier plate in the welding area, the constant-temperature heating device can perform constant-temperature heating on the welding area. The welding area can radiate a certain amount of infrared light to the transparent workpiece, and the infrared light can facilitate the transparent workpiece to absorb the laser, thereby accelerating the welding speed of the transparent workpiece. Since a relatively high temperature is not adopted and the power of the laser is not increased, deformation of the transparent workpiece caused by too high laser power or deformation caused by too high temperature can be avoided. Therefore, the welding efficiency of the transparent workpiece can be improved without causing deformation of the transparent workpiece. The welding speed can be increased from less than 10 mm / s originally to 25 - 30 mm / s currently, showing a significant improvement. Additionally, due to the increased welding efficiency, the thermal accumulation on the transparent workpiece becomes less, resulting in less deformation of the transparent workpiece.

[0019] Thirdly, the laser can be reflected by a reflecting mirror surface, which facilitates the absorption of the laser by the transparent workpiece and improves the welding efficiency of the transparent workpiece. Additionally, due to the increased welding efficiency, the thermal accumulation on the transparent workpiece becomes less, resulting in less deformation of the transparent workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a laser welding device for a transparent workpiece in Embodiment 1 of the present invention;

[0021] Figure 2 is a schematic structural diagram of a laser welder in the laser welding device for a transparent workpiece in Embodiment 1 of the present invention;

[0022] Figure 3 is a schematic structural diagram of a jig in Embodiment 1 of the present invention;

[0023] Figure 4 is a partial exploded schematic diagram of the jig in Embodiment 1 of the present invention;

[0024] Figure 5 is a schematic structural diagram of a heating element of the jig in Embodiment 1 of the present invention;

[0025] Figure 6 is a schematic structural diagram of a transparent workpiece of the jig in Embodiment 1 of the present invention.

[0026] DESCRIPTION OF THE REFERENCE NUMERALS:

[0027] 100 - laser welder; 110 - galvanometer scanner; 140 - lens assembly;

[0028] 200 - jig; 210 - stage; 211 - welding area; 212 - base; 213 - heating base; 214 - bottom plate; 215 - air channel; 220 - carrier plate; 221 - air hole; 230 - pressing seat; 240 - limiting block;

[0029] 300 - transparent workpiece. Detailed implementation manners

[0030] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0032] It should be noted that: like reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0033] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0034] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0035] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "arranged", "installed", "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] Example 1

[0037] This example provides a method for laser welding of transparent workpieces, including:

[0038] When using a laser to weld a transparent workpiece with two layers of transparent materials, adjust the laser spot to a flat-top beam and shorten the laser focal depth so that both layers of transparent materials can absorb laser energy.

[0039] By shaping the Gaussian beam into a flat-top beam and adjusting the focal depth, the upper and lower layers of transparent workpieces can simultaneously absorb the laser, thus realizing the welding of transparent workpieces. After shaping the Gaussian beam into a flat-top beam, generally the welding effect is best near the focus, usually the best within a focal depth of 0 - 3 mm. When the defocus is large, the spot will become a quasi-flat-top and quasi-Gaussian beam, affecting the welding effect.

[0040] Due to the excessive energy at the focus, plastic welding is generally carried out within a certain positive defocus range. The focal depth in the infrared band can be about 0 - 30 mm for welding, and the focal depth for transparent plastic welding is generally only about 0 - 6 mm. However, products with different thicknesses require different focal depths. Therefore, an adjustable focal depth device is made on the external optical path to better accommodate the welding of more products.

[0041] Place the transparent workpiece with two layers of transparent materials on the carrier plate, and place the carrier plate in the welding area. Use a constant temperature heating device to heat the welding area at a constant temperature. In this example, the constant temperature heating device heats the welding area, so that the carrier plate placed on the welding area is within the magnetic field radiated by the welding area. And the welding process is completed in a very short time after placing the carrier plate on the welding area, so that the heat in the welding area has no time to be transferred to the transparent workpiece through the carrier plate. By heating the welding area, the absorption rate of the transparent workpiece to the laser can be effectively increased, and it overcomes the technical prejudice in the prior art that due to the heat accumulation in laser welding, the transparent workpiece 300 needs to be cooled urgently due to deformation, rather than being heated to improve the laser welding efficiency, thereby reducing heat accumulation and reducing the deformation of the transparent workpiece 300.

[0042] Control the temperature of the welding area at 45 - 55 °C. Through experimental tests, it is found that the effect is best when the temperature is between 45 - 55 °C. If the temperature is too low, it cannot accelerate the welding effect, and if the temperature is too high, it will increase the welding deformation and affect the product size.

[0043] Set the corresponding welding track of the carrier plate for the transparent workpiece as a reflective mirror surface. The reflective mirror surface is preferably a sub-mirror smooth surface. Among them, the closer the transparent workpiece is to the welding area, the stronger the reflected laser intensity and the easier it is to weld.

[0044] Place the carrier with the transparent workpiece on the welding area, and the welding area vacuum-absorbs the transparent workpiece through the carrier. The vacuum absorption points of the transparent workpiece are located within the welding track circle. In this way, the transparent workpiece can be better fixed. At the same time, when the vacuum is released, after cold air is filled, the cold air can absorb part of the heat during welding, further avoiding deformation.

[0045] In this embodiment, the wavelength of the laser is 1720nm to 1940nm.

[0046] The laser is shaped by a spot shaping component and an adjustable collimation component to obtain a flat-top light, and the depth of focus can weld the upper transparent material and the lower transparent material of the transparent workpiece.

[0047] The welding speed of the laser is 25 - 30mm / s.

[0048] The method for laser welding of transparent workpieces further includes: pressing the transparent workpiece tightly on the carrier when laser welding the transparent workpiece.

[0049] The method for laser welding of transparent workpieces further includes: continuing to press the transparent workpiece tightly on the carrier for a predetermined time after the transparent workpiece is welded. Preferably, the predetermined time is 1 - 3 seconds. Generally, after welding is completed, keep the pressure for 1 - 3 seconds to allow the plastic to solidify and increase the strength. At the same time, the constant temperature heating device ensures that the product does not cool down too quickly, resulting in excessive stress and cracks.

[0050] Embodiment 2

[0051] Reference Figure 1 And Figure 2 , Figure 1 is a schematic structural diagram of the laser welding device for transparent workpieces in Embodiment 1 of the present invention. Figure 2 is a schematic structural diagram of the laser welder 100 in the laser welding device for transparent workpieces in Embodiment 1 of the present invention. This embodiment provides a laser welding device for transparent workpieces, including a laser welder 100. The laser welder 100 includes a galvanometer 110, an adjustable collimation component, a spot shaping component, and a lens component 140. The laser sequentially passes through the galvanometer 110, the spot shaping component, the adjustable collimation component, and the lens component 140. The spot shaping component and the adjustable collimation component are used to adjust the Gaussian light into a flat-top light, and the adjustable collimation component is also used to adjust the depth of focus of the laser. By adjusting the laser spot shaping and the depth of focus, the upper and lower layers of the transparent workpiece can absorb the laser simultaneously, thereby realizing the welding of the transparent workpiece.

[0052] Reference Figure 3 , Figure 4 , Figure 5 And Figure 6 , Figure 3 is a schematic structural diagram of the fixture 200 in Embodiment 1 of the present invention. Figure 4It is a partial exploded view of the jig 200 in the first embodiment of the present invention. Figure 5 It is a schematic structural view of the heating element of the jig 200 in the first embodiment of the present invention. Figure 6 It is a schematic structural view of the transparent workpiece 300 of the jig 200 in the first embodiment of the present invention. The transparent workpiece and laser welding device further includes a jig 200, and the jig 200 includes a stage 210. The stage 210 includes a heating base 213 and a carrier plate 220 for welding the transparent workpiece. A constant temperature heating device is provided in the heating base 213, and the carrier plate 220 is fitted and installed on the welding area 211 of the heating base 213.

[0053] When placing a transparent workpiece with two layers of transparent materials on the carrier plate 220 and placing the carrier plate 220 in the welding area 211, the constant temperature heating device can perform constant temperature heating on the welding area 211. The welding area 211 can radiate a certain amount of infrared light to the transparent workpiece, and the infrared light can facilitate the transparent workpiece 300 to absorb the laser, thereby accelerating the welding speed of the transparent workpiece 300. Since a relatively high temperature is not adopted and the power of the laser is not increased, deformation of the transparent workpiece 300 caused by too high laser power or deformation caused by too high temperature can be avoided. Therefore, the welding efficiency of the transparent workpiece 300 can be improved without causing deformation of the transparent workpiece 300. The welding speed can be increased from less than 10 mm / s originally to 25 - 30 mm / s now, showing a significant improvement. In addition, due to the improvement of the welding efficiency, the heat accumulation on the transparent workpiece 300 becomes less, resulting in less deformation of the transparent workpiece 300. The deformation amount can be changed from the original 100 microns to about 5 microns now.

[0054] In this embodiment, the temperature of the welding area is controlled at 45 - 55 °C. Through experimental tests, it is found that the effect is the best when the temperature is between 45 - 55 degrees. If the temperature is too low, the welding acceleration effect cannot be achieved, and if the temperature is too high, the welding deformation amount will increase, affecting the product size.

[0055] A reflecting mirror surface is provided at the welding track of the carrier plate 220 corresponding to the transparent workpiece 300. In this way, the laser can be reflected by the reflecting mirror surface, so as to facilitate the absorption of the laser by the transparent workpiece and improve the welding efficiency of the transparent workpiece. In addition, due to the improvement of the welding efficiency, the heat accumulation on the transparent workpiece becomes less, resulting in less deformation of the transparent workpiece.

[0056] Preferably, the reflecting mirror surface is a sub-mirror smooth surface, which is processed by sub-mirror polishing technology.

[0057] Air holes 221 are formed on the carrier plate 220. So as to fix the transparent workpiece 300 on the carrier plate 220 by adsorption during welding.

[0058] Reference Figure 4 and Figure 5, the heating base 213 further includes a bottom plate 214, the constant temperature heating device is arranged in the bottom plate 214, and the bearing surface 211 is located on the bottom plate 214.

[0059] The heating base 213 further includes an air duct 215, the air duct 215 is opened on the bottom plate 214, one end of the air duct 215 penetrates through the bearing surface 211, and the air hole 221 is communicated with the air duct 215. By arranging the air duct 215 to adsorb the transparent workpiece 300 on the carrier plate 220, the deformation of the transparent workpiece 300 during the welding process can be avoided, so as to achieve the purpose of reducing deformation.

[0060] In this embodiment, the number of the air ducts 215 is multiple, the constant temperature heating device includes multiple heating elements, and the multiple heating elements and the air ducts 215 are arranged at intervals.

[0061] Reference Figure 5 , preferably, the number of the air ducts 215 is three, the number of the heating elements is preferably two, the three air ducts 215 are arranged side by side, and the two heating elements are arranged side by side.

[0062] Preferably, the carrier stage 210 further includes a base 212, and the heating base 213 can slide horizontally relative to the base 212. In this way, it is convenient to load and unload the carrier plate 220.

[0063] The transparent workpiece laser welding jig 200 further includes a pressing base 230, the pressing base 230 can lift vertically relative to the base 212, and the base 212 is located on the lifting path of the pressing base 230. By lifting the pressing base 230, the distance between the carrier stage 210 and the pressing base 230 can be changed. When the distance between the carrier stage 210 and the pressing base 230 is the smallest, the pressing base 230 presses the transparent workpiece 300 on the carrier plate 220 on the carrier stage 210. In this way, the deformation of the transparent workpiece 300 during the welding process can be avoided.

[0064] The pressing base 230 and the base 212 are connected by a slide rail.

[0065] The pressing base 230 is provided with a limit stop 240, and the limit stop 240 cooperates with the base 212 to prevent the distance between the pressing base 230 and the heating base 213 from being too small and damaging the transparent workpiece 300.

[0066] The pressing base 230 includes a pressing frame and a pressing plate. The pressing frame is connected to the base 212 by a slide rail. The pressing frame is in a door shape, and the pressing plate is arranged at the top of the pressing frame and inside the pressing frame. The pressing plate cooperates with the carrier plate to press the transparent workpiece tightly.

[0067] A buffer structure is provided between the pressing plate and the pressing frame, thus avoiding damage to the transparent workpiece during the pressing process.

[0068] Welding windows through which the laser can pass are provided at the top of the pressing frame and the pressing plate.

[0069] The transparent workpiece laser welding device further includes a temperature control meter for measuring the temperature of the heating base 213. The transparent workpiece laser welding device further includes a vacuum gauge for detecting the vacuum degree of the vacuum adsorption.

[0070] The working process of the transparent workpiece laser welding device is as follows:

[0071] First step, the constant temperature heating device performs constant temperature heating on the heating base.

[0072] Second step, place the transparent workpiece on the carrier plate 220.

[0073] Third step, place the carrier plate 220 on the heating base 213.

[0074] Fourth step, vacuum-adsorb the workpiece on the carrier plate 220.

[0075] Fifth step, the heating base 213 slides horizontally relative to the base 212 to directly below the pressing seat 230.

[0076] Sixth step, the pressing seat 230 presses down.

[0077] Seventh step, the laser welder 100 welds the workpiece.

[0078] Eighth step, the pressing seat 230 maintains pressure for a predetermined time.

[0079] Ninth step, the pressing seat 230 rises, the heating base 213 slides horizontally relative to the base 212 to one side of the pressing seat 230, and the vacuum adsorption stops.

[0080] Tenth step, remove the carrier plate 220 from the heating base 213.

[0081] Eleventh step, remove the transparent workpiece from the carrier plate 220.

[0082] The transparent workpiece in the present invention can be transparent plastic. Since the laser welding jig and device in the present invention can reduce the deformation of the upper transparent plastic and the lower transparent plastic during the welding process, the welded transparent plastic has the characteristics of high welding accuracy and no pollution, and thus can meet the requirements of high precision and high cleanliness of medical devices.

[0083] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure fall within the scope of protection of the claims.

Claims

1. A method for laser welding of transparent workpieces, characterized in that, Including: When using a laser to weld and process a transparent workpiece with two layers of transparent materials, adjust the laser spot to a flat-top beam and shorten the laser focal depth so that both layers of transparent materials absorb laser energy.

2. The laser welding method for a transparent workpiece according to claim 1, wherein, Place the transparent workpiece with two layers of transparent materials on a carrier plate, and place the carrier plate in the welding area. Use a constant-temperature heating device to heat the welding area at a constant temperature.

3. The laser welding method for a transparent workpiece according to claim 2, characterized in that, Control the temperature of the welding area at 45 - 55 °C.

4. The laser welding method for a transparent workpiece according to claim 2, characterized in that, Set the area corresponding to the welding track of the transparent workpiece on the carrier plate as a reflective mirror surface.

5. The method for laser welding of transparent workpieces according to claim 2, characterized in that, Place the carrier plate with the transparent workpiece in the welding area, and the welding area vacuum-sucks the transparent workpiece through the carrier plate. The vacuum suction points of the transparent workpiece are located within the circle of the welding track.

6. The laser welding method for a transparent workpiece according to claim 1, characterized in that, The wavelength of the laser is 1720 nm to 1940 nm.

7. The laser welding method for a transparent workpiece according to claim 6, wherein Shape the laser through a spot shaping component and an adjustable collimation component to obtain a flat-top beam, and the focal depth can weld the upper transparent material and the lower transparent material of the transparent workpiece.

8. The laser welding method for a transparent workpiece according to claim 1, characterized in that, The welding speed of the laser is 25 - 30 mm / s.

9. A laser welding device for a transparent workpiece, comprising a laser welder, characterized in that, The laser welder includes a galvanometer, an adjustable collimation component, a spot shaping component, and a lens component. The laser passes through the galvanometer, the spot shaping component, the adjustable collimation component, and the lens component in sequence. The spot shaping component and the adjustable collimation component are used to adjust the Gaussian beam to a flat-top beam, and the adjustable collimation component is also used to adjust the focal depth of the laser.

10. The laser welding device according to claim 9, characterized in that, It further includes a stage. The stage includes a heating base and a carrier plate for welding the transparent workpiece. A constant-temperature heating device is provided in the heating base, and the carrier plate is fitted and installed on the welding area of the heating base.

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