A device for laser welding of plastics using mechanical cavity homogenization of the laser application

Abstract

The application discloses a device for plastic welding by using a mechanical cavity homogenization laser, which comprises a laser for emitting a laser beam and transmitting the emitted laser beam into a mechanical homogenization cavity through a plurality of optical fibers; the mechanical homogenization cavity is used for reflecting the laser beams output by the plurality of optical fibers in the cavity, so that the laser beams which do not intersect with each other are superimposed, and energy distribution homogenization is realized; a clamping jig assembly is used for fixing the mechanical homogenization cavity and a plastic welding product; and a driving assembly is used for driving the clamping jig assembly to open and close. The application solves the problems of uneven multi-beam splicing or high machining complexity and machining requirement in the current laser synchronous welding application.

Description

TECHNICAL FIELD

[0001] The present application relates to laser plastic welding applications, especially for mass production, plastic welding products with high production efficiency requirements, and specifically to a device for plastic welding using a mechanical cavity homogenization laser. BACKGROUND

[0002] There are generally three different processes for laser plastic welding applications, namely contour welding, scanning welding and synchronous welding.

[0003] Contour welding: the laser moves along the contour line of the plastic welding layer and melts it, gradually bonding the plastic layers together; or the sandwiched layer is moved along the fixed laser beam to achieve the purpose of welding. Now commonly used is composite contour welding, that is, high-intensity laser light source combined with halogen light source to heat and weld together. This contour welding method allows transparent face shields to have no welding ribs, so the welding appearance is beautiful.

[0004] Scanning welding: scanning welding technology uses a mirror to generate a high-speed laser beam at a speed of 10 meters per second, which moves along the part to be welded, causing the entire welded part to gradually heat up and fuse together. The contour and shape of the welding have more stringent requirements, and are more suitable for welding products with relatively flat contours and small sizes, or for welding local areas of parts.

[0005] Synchronous welding: multiple optical fibers are used to guide the laser to the contour line along the welding surface, generating heat at the weld seam, so that the entire contour line melts and bonds together at the same time.

[0006] Compared with the above two methods, the most widely used method for plastic welding is still the first two methods. However, as the trend of product design is becoming more and more complex and three-dimensional, flat products are no longer common. Therefore, the application range of contour welding and scanning welding is becoming narrower and narrower, and the synchronous welding method is being used more and more. However, the current synchronous welding has the problems of uneven multi-beam splicing and complex and high processing requirements of narrow waveguide optical parts, making it difficult to realize.

[0007] After searching, a synchronous laser plastic welding machine disclosed in Chinese patent CN112721190A includes an upper mold provided with a plurality of laser emitting components, a lower mold for placing a workpiece to be welded, a limiting guide column for limiting the upper and lower molds, and a lower mold lifting mechanism for closing the upper and lower molds. The light output by the laser irradiates the welding part of the workpiece. The energy distribution of the patent application is similar to that shown in FIG. 1, and the energy distribution is uneven, and the plastic welding track is also uneven. Figure 2 SUMMARY

[0008] ​In order to overcome the above-mentioned deficiencies of the prior art, the present application provides a device for plastic welding by using mechanical cavity homogenization laser, which is used to solve the problems of uneven multi-beam splicing or high processing requirement of complex narrow waveguide optical devices in the current laser synchronous welding application.

[0009] The present application is realized by the following technical solutions:

[0010] The device for plastic welding by using mechanical cavity homogenization laser comprises a laser for emitting a laser beam and transmitting the emitted laser beam into a mechanical homogenization cavity through a plurality of optical fibers; a mechanical homogenization cavity for reflecting the laser beams output by the plurality of optical fibers in the cavity to make the laser beams that do not intersect with each other superimposed and realize energy distribution homogenization; a clamping fixture assembly for fixing the mechanical homogenization cavity and a plastic welding product; and a driving assembly for driving the clamping fixture assembly to open and close.

[0011] The above technical solution adopts a method of setting a mechanical cavity to homogenize laser, effectively solves the problem of uneven multi-beam splicing, and the mechanical cavity which is not complex to process can achieve the homogenization effect that can only be realized by high-difficulty optical devices, greatly reducing the implementation difficulty and cost of synchronous welding.

[0012] As a further technical solution, the reflectivity of the reflective inner wall of the mechanical homogenization cavity is required to be greater than or equal to 85%, the roughness is less than or equal to 3.2um, and the surface is plated with inert metal.

[0013] When the laser beams emitted by the plurality of optical fibers enter the inner surface of the cavity, the divergent beams output by a single optical fiber enter the inner surface of the cavity for multiple reflections, and the beams of the plurality of optical fibers are superimposed on the reflective surface to realize homogenization, thereby realizing homogenization of incident light energy distribution. Moreover, the homogenization by parallel reflection can produce an infinite long spatial 3D homogenized laser result, which can achieve better homogenization effect.

[0014] As a further technical solution, the light inlet surface of the mechanical homogenization cavity is provided with a plurality of light inlet openings for respectively connecting the plurality of optical fibers, and the light outlet surface is provided with a light outlet opening for making the homogenized light beams incident on the surface of the plastic welding product to be processed.

[0015] Optionally, a light inlet path is preset on the light inlet surface of the mechanical homogenization cavity, and a plurality of light inlet openings are formed on the light inlet path. The laser beams transmitted by the plurality of optical fibers enter the inside of the mechanical homogenization cavity through the light inlet openings on the light inlet path.

[0016] Optionally, the size of the light inlet opening is matched with the size of the end surface of the optical fiber.

[0017] As a further technical solution, the plurality of light inlet openings are uniformly arranged and arranged along the preset light inlet path on the light inlet surface.

[0018] Optionally, the preset light inlet path is rectangular, square, circular or other irregular shape.

[0019] As a further technical solution, the distance between the light outlet surface of the mechanical homogenization cavity and the fiber exit end surface is less than the cavity depth * numerical aperture.

[0020] The cavity depth refers to the distance in the depth direction of the parallel plane. The parallel plane refers to the plane parallel to the cavity wall and passing through the optical axis of the fiber.

[0021] Specifically, the numerical aperture (NA) is a dimensionless number of an optical system, which measures the angular range of light that the system can collect. In the field of optical fibers, the numerical aperture describes the size of the cone angle when light enters and exits the optical fiber.

[0022] As a further technical solution, a dust extraction assembly is arranged in the mechanical homogenization cavity. Compared with the prior art, the interior of the mechanical homogenization cavity is an empty cavity without narrow waveguide optical devices, so that the dust extraction device can be arranged in the internal empty cavity to process the smoke and dust in the welding process, thereby effectively improving the service life of the device and reducing the maintenance cost.

[0023] As a further technical solution, the distance between the optical fibers is less than the cavity depth * numerical aperture of the mechanical homogenization cavity.

[0024] As a further technical solution, the clamp assembly includes an upper cover, a lower cover and a middle plate, the upper cover is used to fix the mechanical homogenization cavity, the middle plate is used to fix the clamp, the clamp is used to fix the plastic welding product, and the mechanical homogenization cavity and the clamp are parallel to each other.

[0025] Optionally, the light outlet surface of the mechanical homogenization cavity is parallel to the upper surface of the clamp. In this way, the light outlet surface of the mechanical homogenization cavity can better contact the surface of the product to be welded, so as to ensure the welding effect.

[0026] Optionally, the mechanical homogenization cavity is arranged in the middle part of the upper cover, and the clamp is arranged in the middle part of the middle plate. The positions of the mechanical homogenization cavity and the clamp are matched.

[0027] As a further technical solution, a guide rod is arranged between the upper cover and the lower cover, and the middle plate is arranged on the guide rod and can move along the guide rod under the driving of the driving assembly.

[0028] Optionally, a plurality of guide rods are arranged between the upper cover and the lower cover, which are used to support the middle plate and provide a moving track for the middle plate.

[0029] Optionally, the driving assembly is realized by a pneumatic cylinder.

[0030] Before processing, the clamping fixture assembly is driven upward by the driving assembly, and the plastic welding sample to be welded is placed on the clamping fixture; then the clamping fixture assembly is driven downward by the driving assembly, so that the light emitting surface of the mechanical homogenization cavity moves downward and is pressed to the surface of the product to be welded.

[0031] As a further technical solution, the driving assembly is arranged outside the lower cover, and the driving shaft thereof abuts against the middle plate through the lower cover.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] (1) The present application adopts a mechanical homogenization cavity, so that the laser energy is uniformly distributed, the welding penetration consistency is good during plastic welding, and the sealing effect is good. Since the mechanical cavity is used to realize laser homogenization, compared with the narrow waveguide mode, the narrow waveguide optical device is omitted, and the cost and processing difficulty are greatly reduced.

[0034] (2) The inside of the mechanical homogenization cavity is an empty cavity without narrow waveguide optical devices, so that a dust extraction device can be arranged in the empty cavity, so that the smoke and dust in the welding process can be conveniently treated in actual application, thereby effectively improving the service life of the device and reducing the maintenance cost.

[0035] (3) Compared with the original track welding and scanning welding, the processing efficiency is greatly improved, and the inconsistency caused by the focal plane and motion control in complex space track processing is avoided.

[0036] (4) The present application is suitable for large-scale production of plastic welding products with high production efficiency requirements. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 (a)-(b) are schematic diagrams of the device according to an embodiment of the present application.

[0038] Figure 2 is a schematic diagram of energy distribution on the welding track.

[0039] Figure 3 is a schematic diagram of energy distribution on the welding track according to an embodiment of the present application.

[0040] Fig. 4(a)-(c) is a cross-sectional view of the mechanical homogenization cavity according to an embodiment of the present application.

[0041] Figure 5 is an axial view of the light emitting surface of the mechanical homogenization cavity according to an embodiment of the present application.

[0042] Figure 6 is an axial view of the light emitting surface of the mechanical homogenization cavity according to an embodiment of the present application.

[0043] Figure 7 is a schematic diagram of laser energy distribution of a fiber exit according to an embodiment of the present application.

[0044] Figure 8 is a simulation diagram of a homogenization shaft of a plurality of fibers entering a mechanical homogenization cavity according to an embodiment of the present application.

[0045] Figure 9 is a schematic diagram of a homogenization longitudinal section of a single fiber entering a mechanical homogenization cavity according to an embodiment of the present application.

[0046] Figure 10 is a simulation diagram of energy partial distribution of a mechanical homogenization cavity after homogenization according to an embodiment of the present application.

[0047] In the figure: 1 - laser; 2 - mechanical homogenization cavity; 3 - guide rod; 4 - clamp fixture; 5 - air cylinder. DETAILED DESCRIPTION

[0048] The technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0049] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features referred to. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0052] like Figure 1 As shown in (a)-(b), the present invention provides an apparatus for applying laser homogenization using a mechanical cavity to plastic welding, comprising a laser, a mechanical homogenization cavity, a jig assembly, and a drive assembly. The laser emitted is connected to the mechanical homogenization cavity via multiple optical fibers. The jig assembly includes a jig and components for supporting the jig. The drive assembly is connected to the jig assembly and is used to drive the jig assembly to open and close.

[0053] Specifically, the laser emits a laser beam and transmits the emitted laser beam to the mechanical homogenization cavity through multiple optical fibers; the mechanical homogenization cavity reflects the laser beams output from the multiple optical fibers within the cavity, so that the non-intersecting laser beams are superimposed to achieve homogenization of energy distribution; the clamping fixture assembly fixes the mechanical homogenization cavity and the plastic welding product; the drive assembly drives the clamping fixture assembly to open and close.

[0054] Optionally, the reflectivity of the inner wall of the mechanical homogenizing cavity is required to be ≥85%, the roughness ≤3.2µm, and the surface is plated with an inert metal such as gold or iridium. Through the mechanical homogenizing cavity, the reflectivity of the inner wall is... Figure 2 The non-uniform energy distribution state of multiple optical fibers is homogenized into Figure 3 state.

[0055] When laser beams emitted from multiple optical fibers enter the inner surface of the cavity, the divergent beams from a single fiber undergo multiple reflections within the cavity surface. Simultaneously, the beams from multiple fibers superimpose parallel to the reflecting surface, homogenizing the energy distribution of the incident light. Furthermore, using parallel reflecting surfaces for homogenization can produce infinitely long spatial 3D homogenized laser results, achieving even better homogenization effects.

[0056] As shown in Figures 4(a)-(c), the light-inlet surface of the mechanical homogenizing cavity is provided with several light-inlet ports for connecting multiple optical fibers respectively; the light-outlet surface is provided with light-outlet ports for incidenting the homogenized light beam onto the surface of the plastic welding product to be processed.

[0057] Optionally, such as Figure 5 and 6 As shown, a light-inlet path is preset on the light-inlet surface of the mechanical homogenizing cavity, and several light-inlet ports are opened on the light-inlet path. Laser beams transmitted by multiple optical fibers enter the interior of the mechanical homogenizing cavity through the light-inlet ports on the light-inlet path.

[0058] Optionally, the size of the light inlet is adapted to the end face size of the optical fiber.

[0059] Optionally, a plurality of the light inlets are evenly distributed and arranged along a preset light inlet path on the light inlet surface.

[0060] Optionally, the preset light-entry path can be rectangular, square, circular, or other irregular shapes. As long as it allows the light beams transmitted through multiple optical fibers to enter the cavity and be homogenized, the present invention does not limit the specific shape of the light-entry path. Similarly, the present invention does not limit the shape of the mechanical homogenization cavity, only requiring that it has a cavity and that the light-emitting surface is parallel to the upper surface of the fixture.

[0061] Optionally, the distance between the light-emitting surface of the mechanical homogenizing cavity and the light-emitting end face of the optical fiber is less than the cavity depth multiplied by the numerical aperture.

[0062] Specifically, numerical aperture (NA) is a dimensionless number for an optical system, used to measure the angular range of light that the system can collect. In the field of optical fibers, numerical aperture describes the cone angle of light entering and exiting the optical fiber.

[0063] like Figure 8 and 9 As shown, after the laser beams emitted from multiple optical fibers enter the mechanical homogenization cavity, the divergent beams output from a single optical fiber enter the inner surface of the cavity and undergo multiple reflections. At the same time, the beams from multiple optical fibers are parallel to the reflecting surface and superimposed on each other to homogenize, thereby achieving homogenization of the incident light energy distribution.

[0064] Figure 7For the mechanical homogenization cavity of the present application, the energy output from the optical fiber cannot form the uniform energy of the required track shape on the plastic welding track. Figure 10 For the mechanical homogenization cavity, the partial segment energy has formed the uniform energy of the track shape, Figure 10 For Figure 3 the partial segment.

[0065] Optionally, a dust extraction assembly is arranged in the mechanical homogenization cavity. Compared with the prior art, the interior of the mechanical homogenization cavity is an empty cavity without narrow waveguide optical devices, and therefore, the dust extraction device can be arranged in the empty cavity to treat the smoke and dust in the welding process, thereby effectively improving the service life of the device and reducing the maintenance cost.

[0066] Optionally, the distance between the optical fibers is less than the cavity depth * numerical aperture of the mechanical homogenization cavity.

[0067] Optionally, the clamp assembly comprises an upper cover, a lower cover and a middle plate, the upper cover is used to fix the mechanical homogenization cavity, the middle plate is used to fix the clamp, the clamp is used to fix the plastic welding product, and the mechanical homogenization cavity and the clamp are parallel to each other.

[0068] Optionally, the light output surface of the mechanical homogenization cavity is parallel to the upper surface of the clamp. In this way, the light output surface of the mechanical homogenization cavity can better contact the surface of the product to be welded, so as to ensure the welding effect.

[0069] Optionally, the mechanical homogenization cavity is arranged in the middle part of the upper cover, and the clamp is arranged in the middle part of the middle plate, and the positions of the mechanical homogenization cavity and the clamp are matched.

[0070] Optionally, guide rods are arranged between the upper cover and the lower cover, and the middle plate is arranged to penetrate the guide rods and can move along the guide rods under the driving of the driving assembly.

[0071] Optionally, a plurality of guide rods are arranged between the upper cover and the lower cover to support the middle plate and provide a moving track for the middle plate. For example, four guide rods are symmetrically arranged around the upper cover and the lower cover to support the middle plate and move the middle plate along the guide rods.

[0072] Optionally, the driving assembly is realized by a pneumatic cylinder.

[0073] Before processing, the clamp assembly is opened upward by the driving of the driving assembly, and the plastic welding sample to be welded is placed on the clamp; then the clamp assembly is closed downward by the driving of the driving assembly, so that the light output surface of the mechanical homogenization cavity moves downward and is pressed to the surface of the product to be welded.

[0074] Optionally, the driving assembly is arranged outside the lower cover, and the driving shaft of the driving assembly penetrates the lower cover and abuts against the middle plate.

[0075] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some or all of the technical features thereof can be replaced by equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present application.

Claims

1. A device for laser application for plastic welding using mechanical cavity homogenization, characterized in that, The application relates to a laser homogenization device, which comprises a laser for emitting a laser beam and transmitting the emitted laser beam into a mechanical homogenization cavity through a plurality of optical fibers; the mechanical homogenization cavity is used for reflecting the laser beams output by the plurality of optical fibers in the cavity, so that the laser beams are superimposed and the energy distribution is homogenized; after the laser beams output by the plurality of optical fibers enter the mechanical homogenization cavity, the divergent beams output by the single optical fiber enter the inner surface of the cavity and are reflected multiple times, and the beams output by the plurality of optical fibers are superimposed and homogenized parallel to the reflecting surface, so that the energy distribution of the incident light is homogenized; a clamp assembly is used for fixing the mechanical homogenization cavity and a plastic welding product; a driving assembly is used for driving the clamp assembly to open and close; the reflectivity of the reflecting inner wall of the mechanical homogenization cavity is required to be greater than or equal to 85%, the roughness is less than or equal to 3.2 um, and the surface is plated with inert metal; the distance between the light-emitting surface of the mechanical homogenization cavity and the fiber exit end surface is less than the cavity depth * numerical aperture; the distance between the optical fibers is less than the cavity depth * numerical aperture of the mechanical homogenization cavity, and the numerical aperture describes the size of the cone angle when the light enters and exits the optical fiber.

2. The apparatus for plastic welding using mechanical cavity homogenization of laser application according to claim 1, characterized in that, The light inlet surface of the mechanical homogenization cavity is provided with a plurality of light inlet openings for connecting the plurality of optical fibers respectively; and the light-emitting surface is provided with a light outlet opening for making the homogenized light beams enter the surface of the plastic welding product to be processed.

3. The apparatus for plastic welding using mechanical cavity homogenization of laser application according to claim 2, characterized in that, The plurality of light inlet openings are uniformly arranged and arranged along the preset light inlet path on the light inlet surface.

4. The device for plastic welding using mechanical cavity homogenization of laser application according to any of claims 1 - 3, characterized in that, A dust extraction assembly is arranged in the mechanical homogenization cavity.

5. The apparatus for plastic welding using mechanical cavity homogenization of laser application according to claim 1, wherein, The clamp assembly comprises an upper cover, a lower cover and a middle plate; the upper cover is used for fixing the mechanical homogenization cavity; the middle plate is used for fixing the clamp; the clamp is used for fixing the plastic welding product; and the mechanical homogenization cavity and the clamp are parallel to each other.

6. The apparatus for plastic welding using a mechanical cavity homogenizing laser application according to claim 5, wherein, A guide rod is arranged between the upper cover and the lower cover; the middle plate is arranged on the guide rod and can move along the guide rod under the driving of the driving assembly.

7. The apparatus for plastic welding using a mechanical cavity homogenizing laser application according to claim 6, wherein, The driving assembly is arranged outside the lower cover, and the driving shaft of the driving assembly abuts against the middle plate through the lower cover.

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