Components made using laser transmission bonding technology, bonding equipment, and first and second plastic components bonded by laser transmission bonding.

Abstract

This invention discloses a connection method for connecting a first plastic part and a second plastic part using laser transmission bonding technology. The first plastic part absorbs laser light, and the second plastic part is made of transparent plastic, preferably a plastic film. The connection method includes the following steps: S1, positioning the first plastic part in a first tool; S2, positioning the second plastic part in a second tool, such that the first plastic part held by the first tool and the second plastic part held by the second tool are spaced apart from each other, thereby preventing heat exchange between the first and second plastic parts; S3, guiding the laser through the second plastic part to the connection area of ​​the first plastic part, thereby heating the first plastic part at least within the connection area, preferably melting the material of the first plastic part in the connection area; S4, after heating the first plastic part, moving the second plastic part to engage with the first plastic part, preferably pushing the second plastic part towards the first plastic part, so that the second plastic part and the first plastic part are firmly bonded.

Description

Technical Field

[0001] This invention relates to a method for joining first and second plastic components using laser transmission bonding technology. Furthermore, this invention relates to an apparatus for joining a first plastic component and a second plastic component using laser transmission bonding technology, and a laser transmission bonding component made from the first and second plastic components to be joined. Background Technology

[0002] Transmission welding, or laser transmission welding, is a common technique for joining two plastic parts. While the concept of joining two plastic parts is the same, it is also referred to as laser plastic welding, through-transmission welding, or polymer welding. The basic principle of this joining method is to allow laser radiation to pass through or transmit through a piece of plastic to create a weld. Unlike standard welding, which applies energy to the surface of the material, transmission welding aims to apply energy at the interface between two plastic parts. For this purpose, the upper plastic part needs to be transparent to the laser. The lower plastic part is usually designated as the absorber. After the laser transmits through the transparent or upper first plastic part, the incident light is absorbed by the lower plastic part and converted into heat within its material. Once the laser is absorbed and converted into heat by the plastic part, the heat energy is transferred to the transparent plastic part, allowing it to soften and melt. By ensuring a tight fit between the two parts, the heat energy can be conducted to the transparent part. Typically, the parts fit well, but clamping forces are generally used to ensure a good, consistent joint.

[0003] In laser transmission welding of thin films, the bonding materials are typically pressed against each other to induce a substantial flow of molten polymer under heat, thus creating a weld. A problem arises in laser transmission welding of flexible materials (such as plastic films) where the bonding materials themselves lack sufficient rigidity, and the bonding pressure cannot be transmitted through the bonding materials to the weld area. Therefore, for laser transmission welding, the film must be covered by a pressure-applying tool that generates sufficient bonding pressure in the weld area. Direct laser radiation is not feasible if the pressure-applying tool is not designed to be transparent to the laser.

[0004] Furthermore, welding devices are known that transmit laser light to the joint object via a transparent glass sphere. This transparent glass sphere is housed and can roll. The entire device is positioned on the joint object via the glass sphere, such that the joining pressure is applied directly to the welding area through the glass sphere. The device can be moved / displaced by rolling on the glass sphere, allowing it to traverse and weld predetermined contours. A disadvantage of existing systems is that they are relatively sluggish due to their high weight and are unsuitable for welding relatively lightweight components, such as films and injection-molded parts.

[0005] EP1405713 describes a known apparatus for welding using a rollably housed glass ball. The glass ball is housed in a shaft that is mechanically separated from the rest of the apparatus by means of a spring. In this system, the separating component with the glass ball is too sluggish to perform contour welding on a cassette module. Due to the sluggish construction, the glass ball inevitably bounces slightly due to inconsistencies in the joining object following the contour shape.

[0006] EP1440784 describes a device having a transparent glass sphere housed within a shaft component. A hot gas flow guided through the side of the glass sphere preheats the component. Because the glass sphere is housed within a larger device, the device exhibits high inertia. It is known that the large mass and high inertia of the processing head in welding equipment, along with the fiber-optic coupling input of the laser used, result in a welding process characterized by relatively high bonding pressure (which cannot be adjusted as needed), low dynamics, and slow response.

[0007] According to US 6,444,946, only one or two mating surfaces are fully preheated to an intermediate temperature slightly below the working or melting temperature. Thereafter, the mating surfaces are brought into contact and the entire preheated mating surface is heated to the final melting temperature. Then, the molten material, or material in molten state, is simultaneously heated to the other mating surface along the entire length of the joint until it reaches the melting temperature. This ensures that the molten material in both mating zones is homogeneously mixed and solidifies into a solid weld upon cooling. This prevents the molten material from solidifying in some joint areas before both mating zones in all other joint areas reach their melting temperature, i.e., before fusing together. All joint areas melt almost simultaneously, or each joint area remains soft enough in all remaining joint areas to allow the parts to move relative to each other, allowing the softened material to yield or displace. The joint molten material solidifies simultaneously or virtually simultaneously along the entire length and width of the joint, thus also preventing strain increase.

[0008] The process described above requires expensive optical structures to guide, focus, and adjust the laser's penetration and preheat the plastic parts to be joined, bringing them to an intermediate temperature slightly below the operating or melting temperature. Furthermore, the combination of preheating the plastic material and subsequent melting requires several related steps and corresponding execution times.

[0009] Therefore, the object of the present invention is to provide an alternative method for connecting at least two plastic parts, which is less extensive than known methods, particularly a method for connecting plastic parts and a plastic film. Summary of the Invention

[0010] The aforementioned objective is achieved by a connection method for joining a first plastic component and a second plastic component to each other using laser transmission bonding technology according to independent claim 1, an apparatus for joining a first plastic component and at least one second plastic component using laser transmission bonding technology according to independent claim 7, and a component made of a first plastic component and at least one second plastic component according to claim 9. Further developments, advantages, and modifications of the invention are described in the following description, drawings, and claims.

[0011] This invention discloses a connection method for joining a first plastic component and at least one second plastic component to each other using laser transmission bonding technology. The first plastic component absorbs laser light, and the second plastic component is made of transparent plastic, preferably a plastic film. The connection method includes the following steps: S1, positioning the first plastic component in a first tool; S2, positioning the second plastic component in a second tool such that the first plastic component held by the first tool and the second plastic component held by the second tool are spaced apart from each other, thereby preventing heat exchange between the first and second plastic components; S3, guiding the laser light through the second plastic component to the connection area of ​​the first plastic component, whereby the first plastic component is heated at least in the connection area, preferably the material of the first plastic component is melted in the connection area; and S4, after heating the first plastic component, moving the second plastic component to engage with the first plastic component, preferably pushing the second plastic component against the first plastic component, so that the second plastic component is firmly bonded to the first plastic component.

[0012] This laser transmission bonding technology is based on a known laser transmission welding process. In contrast to known processes, the plastic parts to be joined are spaced apart from each other, while the laser heats the first plastic part for absorption. For this purpose, the laser is preferably directed to a subsequent joining area that does not cover the entire first plastic part. Preferably, only the joining area is made of the plastic material for absorption, so as to convert the incident light into heat. Based on this preferred embodiment, if the joining area is also made of a light-absorbing and heat-generating material, the first plastic part can be made of any choice of plastic or non-plastic material.

[0013] According to the process of the invention, only the first plastic component is heated by the incident laser. Preferably, the heat melts the plastic material within the connection area, thereby storing heat within the connection area. This heat is then used to establish a connection between the first absorbing plastic component and at least one second plastic component. While the first plastic component is heated, the first and second plastic components are held within corresponding first and second tools. These tools are movable relative to each other. Therefore, the first and second plastic components can engage with each other to create a connection between them.

[0014] After heating the first plastic component and preferably melting the material within the joining region, thermal energy is stored within the joining region. After the second plastic component is pushed against the first plastic component, the stored thermal energy is partially transferred to the second plastic component to join the two plastic components. The amount of thermal energy is high enough to create a connection between the two components.

[0015] Preferably, the first and second plastic components are firmly bonded to each other. If the heat energy stored in the bonding area of ​​the absorbing plastic components is high enough, the bond between the first and second plastic components is similar to a transmission welding connection.

[0016] More preferably, the heat energy stored in the connection area of ​​the first plastic component also enables the material of the second plastic component that joins the connection area of ​​the first plastic component to melt.

[0017] When the first plastic component and the second plastic component are pushed against each other, the molten plastic material of the first plastic component and / or the second plastic component solidifies and bonds the two components together.

[0018] According to a preferred embodiment of the method of the present invention, the connection method includes the further steps of: turning off the laser after heating the first plastic component, and pushing the second plastic component against the first plastic component without laser light entering the first plastic component.

[0019] According to different preferred embodiments of this bonding method, the first plastic component is exposed to the laser only when the first and second components are spaced apart from each other. This gap is large enough to reduce or prevent heat transfer between the two plastic components. Based on this, the absorbing plastic component is heated individually. This bonding method is preferably used to join the absorbing first plastic component and a transparent or opaque plastic film.

[0020] After the laser source is turned off, the first and second plastic components are pushed against each other, and the molten material of the first component solidifies. When the first and second plastic components are joined, no laser is exposed on the connection area.

[0021] According to an optional preferred embodiment of the invention, the connection method includes the further step of: pushing a second plastic component against a first plastic component while simultaneously guiding a laser through the second plastic component to the connection area.

[0022] According to this preferred embodiment of the invention, the laser penetrates the second plastic component. The first plastic component absorbs the laser energy and transfers it to the second component, film, or membrane via thermal conduction. Simultaneously, the two components press against each other. Thus, additional heat is generated in the connection area by means of the light-absorbing material properties of the first plastic component.

[0023] In another preferred embodiment of the connection method according to the invention, in step S3, the laser is guided to the connection area in at least two stages, wherein (a) the first stage has a laser intensity such that the first plastic component is heated and / or plasticized to support the shape adaptation of the first plastic component for tolerance compensation, and / or (b) the laser intensity is adjusted in the second stage such that the material of the first plastic component melts in the connection area of ​​the first plastic component.

[0024] Depending on the preferred bonding strategy, the laser intensity incident on the bonding area varies. In the first step, the laser intensity generates a certain amount of heat energy in the first plastic component, which allows the shape adaptation of the first component to be used for tolerance compensation. Therefore, the provided heat energy softens or plasticizes the plastic material.

[0025] Based on the second preferred step, a higher amount of heat energy is generated in the connection area of ​​the first absorbing plastic component according to laser exposure. The heat energy generated by light absorption at least partially melts the material within the connection area. This promotes bonding with the second plastic component and corresponding heat transfer. The molten material of the first plastic component wets the surface of the second plastic component, thereby preferably expanding the liquid interface.

[0026] As another preferred alternative to the present invention, the first plastic component is made of any kind of thermoplastic material.

[0027] Furthermore, it is also preferable that the second plastic component is a plastic film made of thermoplastic material.

[0028] The present invention also discloses an apparatus for joining a first plastic component and at least one second plastic component by laser transmission bonding technology, the apparatus having the following features: a first tool adapted to hold the first plastic component made of a light-absorbing material; a second tool adapted to hold the second plastic component, the second plastic component being a plastic film; a laser source adapted to guide a laser through the second plastic component to the first plastic component, such that the first plastic component is heated by the laser; and a moving structure adapted to move the first tool and the second tool relative to each other to push the second plastic component against the heated first plastic component.

[0029] Tools for laser welding or laser bonding are known. They have first and second tools for holding and moving first and second plastic parts, respectively. A second tool is adapted to hold a plastic film. Furthermore, the first and second tools are adapted to perform a bonding motion by which the first and second plastic parts are pushed against each other. The device maintains the pushing engagement between the two plastic parts until the bonding between the first and second plastic parts is complete.

[0030] Preferably, the laser-transmissive film or component is fixed in the laser tool by a mechanical device or vacuum. The plastic film or component can be positioned on top of the absorbing component and transferred to another tool, or it can be manually loaded into the upper tool or inserted via a transfer system. The tool for fixing or positioning the absorbing component is fixed to the machine axis worktable.

[0031] According to a preferred embodiment of the device, the laser source can be turned on and off in a defined manner, such that the first plastic component and the second plastic component abut against each other when both are simultaneously exposed to laser light or when neither is exposed to laser light.

[0032] Furthermore, the present invention discloses an adhesive component made of a first plastic component and at least one second plastic component, wherein the second plastic component is a plastic film with a thickness in the range of 10 μm to 10 mm, and the first plastic component and at least one second plastic component are connected by laser transmission bonding technology. Attached Figure Description

[0033] Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. They show:

[0034] Figure 1 A preferred embodiment of an apparatus for laser transmission bonding of first and second plastic components is shown, wherein the first end and the second plastic component are spaced apart from each other.

[0035] Figure 2 It shows Figure 1 The device wherein a first plastic component and a second plastic component are bonded together by pushing the first plastic component and the second plastic component against each other.

[0036] Figure 3 A preferred embodiment of an apparatus for laser transmission bonding of first and second plastic components is shown, wherein the lower tool supporting the absorbing component is preferably laterally movable between a heated position and a connection position with the transparent second component.

[0037] Figure 4 A flowchart illustrating a preferred embodiment of a joining method for bonding first and second plastic components together by laser transmission is shown. Detailed Implementation

[0038] Figure 1 A preferred embodiment of a device 1 for connecting a first plastic component A and at least one second plastic component B is shown. The first plastic component A is adapted to absorb light, particularly laser light. The absorbed laser light is converted into heat energy within the plastic material of the first plastic component A. Therefore, the first plastic component A is also referred to as an absorbing part.

[0039] Typical examples of plastic laser light-absorbing materials include thermoplastic materials suitable for laser transmission welding.

[0040] The second plastic component B is preferably made of a transparent plastic material. The transparency of the second plastic component is used to guide the laser through the second plastic component B to the first absorbing plastic component A.

[0041] According to a preferred embodiment of the second plastic component B, it is made of a plastic film. The preferred thickness of the plastic film is in the range of 10 μm to 10 mm.

[0042] According to another preferred embodiment of the material selection for the second plastic component B, it is made of an opaque plastic film. The preferred thickness of this opaque plastic film B is in the range of 10 μm to 10 mm.

[0043] Furthermore, the aforementioned transparent films preferably possess different physical properties. According to a preferred alternative, the film constitutes a membrane. A membrane allows material and / or energy transfer through the membrane or through its various portions. Furthermore, the membrane is used to separate certain components or substances from each other. According to another preferred embodiment of the film, the membrane is adapted to convert, absorb, or transmit energy or forces acting on the film or membrane.

[0044] If an opaque plastic film B is used as the second plastic component, the first plastic component A will be exposed to the laser, and the second opaque plastic component will not be positioned on top of the first plastic component A or within the laser beam guided to the absorber A. Therefore, thermal energy will be stored in the first plastic component A in a manner similar to that in a laser transmission welding process. After the laser has heated the first plastic component A in the preferred connection area 50, the opaque film, preferably used as the second plastic component B, will be pushed against the first plastic component A. Preferably, the molten plastic material in the connection area 50 of the first plastic component A will adhere to the opaque plastic film to form a connection between the first plastic component A and the second plastic component B. For this purpose, the molten material in the connection area 50 of the first plastic component A is solidified in close contact with the second plastic component B.

[0045] like Figure 1 and 2 As shown, the first plastic component A is held by the first tool 10. Within the first tool 10, the first plastic component A is clamped, mounted, vacuum-held, or releasably secured according to known techniques.

[0046] The second plastic component B is held by the second tool 20. According to a preferred embodiment of the second tool 20, a vacuum holder is provided for holding the second plastic component B. For this purpose, the second tool 20 preferably has a plurality of suction heads 22. The plurality of suction heads 22 create a vacuum at a corresponding opening 24. The second plastic component B is placed on the opening 24 and the opening 24 is blocked. Thus, the second plastic component B is releasably held by the second tool 20.

[0047] Furthermore, a laser source 30 is mounted on the second tool 20. The laser source 30 refers to any suitable light source configuration that guides light to the second tool 20. Therefore, the laser source 30 may include an optical fiber bundle, a laser bank (not shown), at least one brick laser diode (not shown), a separate light guide, etc.

[0048] A preferred laser source 30 provides a laser 32, which is guided to the first plastic component A via a waveguide 40. The laser 32 is preferably focused via the waveguide 40 onto the connection region 50 of the first plastic component A or the absorber A.

[0049] After the first plastic component A is positioned in and held by the first tool 10 and the second plastic component B is positioned in and held by the second tool 20 (see...) Figure 3 In steps S1 and S2), the first component A and the second component B are positioned at a distance d from each other (see...). Figure 1 The preferred distance d is large enough to prevent heat transfer between the two plastic components A and B. Regardless of the distance d, the plastic components A and B are oriented relative to each other in such a way that the laser 32 emitted from the preferred waveguide 40 encounters the connection region 50 of the first plastic component A. Since the laser 32 is absorbed by the plastic material within the connection region 50, the material of the connection region 50 is heated or melted depending on the intensity of the laser 32. It should be noted that the second plastic component B is a transparent plastic component B or a transparent or non-transparent plastic film B.

[0050] The heated material within the connection region 50 is melted or softened, thus enabling it to be used for shape adaptation of the first plastic component A. This shape adaptation or tolerance compensation is used when the first plastic component A and the second plastic component B move to engage with each other. Preferably, the first plastic component A and the second plastic component B are pushed against each other until the material within the connection region 50 solidifies (step S4).

[0051] According to a preferred embodiment of the invention, when the first plastic component A and the second plastic component B are arranged at a distance d from each other, the material of the first plastic component A within the connection region 50 is heated. The laser 32 used for heating the material in the connection region 50 is turned off before the distance d is reduced and the first plastic component A and the second plastic component B are pushed together. The plastic components A and B are pushed together and remain tightly joined, such that the first plastic component A is adhered to the second plastic component B within the connection region 50.

[0052] According to another preferred embodiment of the invention, laser exposure of the bonding region 50 continues as the first plastic component A and the second plastic component B are pushed against each other. After a certain period of bonding between components A and B, the laser 32 is turned off and the plastic material within the bonding region 50 is cured. In this bonding alternative, the second plastic component B is transparent.

[0053] To achieve movement of the first tool 10 and the second tool 20 relative to each other, an electric, pneumatic, or hydraulic moving device is provided. Such a construction is known in the art.

[0054] According to such Figure 3 Another preferred embodiment of the invention is illustrated in the figure.

[0055] The material within the connection region 50 of the first plastic component A is heated by the laser 32, and the first plastic component A is positioned below the laser source (e.g., the exit end of the waveguide 40). The second plastic component B, to be connected to the heated plastic component A, is positioned at a distance from the laser source (see [reference]). Figure 3 a) This arrangement allows for the separate preparation of components to be connected. This is particularly helpful when components A and B require different environmental conditions, such as temperature, humidity, and radiation. Furthermore, while component A is being heated, component B is preferably protected from environmental or corrosive influences.

[0056] After component A is sufficiently heated within its connection area 50, the heated component A moves relative to component B. The relative movement of components A and B is determined by… Figure 3 The motion arrow in B indicates the movement of component A (as shown in the figure), or components A and B, or only component B. Movement is performed using known drive technologies, such as electric, pneumatic, or hydraulic drives. Furthermore, the movement of components A and B is achieved through linear or curved paths, or a combination thereof.

[0057] After the above-mentioned parts movement is completed, parts A and B are arranged as follows: Figure 3The connection position is shown in C. In this preferred arrangement, the second component B is held at the upper tool 60 by a vacuum source or the like. To connect components A and B together, components A and B move relative to each other to engage in the connection area 50. This movement is preferably performed by the upper tool 60. During the engagement of components A and B within the connection area 50, components A and B are bonded or adhered to each other.

[0058] According to the present invention, the heat energy stored in the connection region 50 is sufficient to produce a reliable connection or adhesion between the first plastic component A and the second plastic component B.

[0059] According to a preferred embodiment of the present invention, the second plastic component B is a plastic film. The preferred thickness of the plastic film is in the range of 10 μm to 10 mm.

[0060] Furthermore, the plastic film is preferably made of thermoplastic material.

[0061] Depending on the light intensity used to expose the connection area 50, the plastic material of the first plastic component A is heated or plasticized, or it melts within the connection area 50. Based on the laser processing, the thermal energy stored within the material of the connection area 50 is sufficient to bond the plastic film B to the first plastic component A. Preferably, the laser 32 is cut off before the first plastic component A and the plastic film B come into contact and bond.

[0062] Based on the above bonding method, the bonding component is manufactured from the first plastic component A and the second plastic component B, preferably a plastic film as defined above.

[0063] List of reference numerals

[0064] 1. Connecting device

[0065] 10 First Tool

[0066] 20 Second Tool

[0067] 22 suction heads

[0068] 24 Opening

[0069] 30 laser sources

[0070] 32 lasers

[0071] 40 waveguide

[0072] 50 Connection area on the first plastic component

[0073] 60 Upper Tools

[0074] A absorbent plastic component, first plastic component

[0075] B. Transparent plastic component, second plastic component

[0076] d. Distance between the first and second plastic components

Claims

1. A joining method for joining a first plastic part and a second plastic part to each other by a laser transmission bonding technique, wherein, The first plastic component absorbs laser light and the second plastic component is made of a transparent plastic, wherein the second plastic component is a plastic film having a thickness in the range of 10 μm to 10 mm, and the joining method comprises the following steps: S1 positioning the first plastic component in a first tool, S2 positioning the second plastic component in a second tool such that the first plastic component held by the first tool and the second plastic component held by the second tool are spaced apart from each other, thereby preventing mutual heat exchange between the first plastic component and the second plastic component, S3 directing laser light through the second plastic component onto a joining region of the first plastic component, whereby the first plastic component is heated at least in the joining region, the material of the first plastic component being melted in the joining region, S4 after heating the first plastic component, moving the second plastic component into engagement with the first plastic component, pushing the second plastic component against the first plastic component such that the second plastic component is firmly bonded to the first plastic component; wherein the method comprises the further step of switching off the laser light after heating the first plastic component and pushing the second plastic component against the first plastic component without laser light entering the first plastic component, such that the first plastic component is exposed to laser light only when the first and second components are spaced apart from each other.

2. The joining method according to claim 1, wherein in step S3 the laser light is directed onto the joining region in at least two phases, wherein (a) in a first phase a laser intensity is included which is able to heat and / or plasticize the first plastic component to support a shape adaptation of the first plastic component for tolerance compensation, and (b) in a second phase the laser intensity is adjusted such that the material of the first plastic component is melted in the joining region of the first plastic component.

3. The joining method according to claim 1 or 2, wherein the first plastic component is made of a thermoplastic material.

4. An apparatus for joining a first plastic component and at least one second plastic component by the joining method according to one of claims 1 to 3, having the following features: a first tool, which is adapted to hold the first plastic component made of a light-absorbing material, a second tool, which is adapted to hold a second plastic component, which is a plastic film and has a thickness in the range of 10 μm to 10 mm, a laser light source, which is adapted to direct laser light through the second plastic component onto the first plastic component such that the first plastic component is heated by the laser light, and a movement arrangement, which is adapted to move the first tool and the second tool relative to each other to push the second plastic component against the heated first plastic component.

5. The apparatus of claim 4, wherein the laser source is capable of switching on and off in a defined manner such that the first plastic part and the second plastic part push against each other without laser entering the second plastic part at the same time.

6. A component made of a first plastic part and at least one second plastic part, wherein the second plastic part is a plastic film having a thickness in the range of 10 μιη to 10 mm, and the first plastic part and the at least one second plastic part are connected by a laser transmission bonding technique using a joining method according to one of claims 1 to 3.

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