阅读说明：本技术 用于窄型同步激光塑料焊接的波导 (Waveguide for narrow synchronous laser plastic welding ) 是由 斯科特·考德威尔 于 2019-01-18 设计创作，主要内容包括：窄的波导(306)使从激光器模块的激光源行进穿过包括至少一个光纤束腿部(304)的多个激光输送束的激光均匀化,从而沿比光纤束腿部(304)的宽度(322)窄的焊接线(314)对多个工件(308,310)进行焊接。该窄的波导(306)具有与每个光纤束腿部(304)相关联的部分(316),该部分比与波导(306)的该部分相关联的光纤束腿部(304)窄。反射性反弹平面(312)使光纤束腿部(304)的不会行进通过窄的波导(306)的激光转向。(The narrow waveguide (306) homogenizes laser light traveling from a laser source of the laser module through a plurality of laser delivery beams including at least one fiber bundle leg (304) to weld a plurality of workpieces (308, 310) along a weld line (314) that is narrower than a width (322) of the fiber bundle leg (304). The narrow waveguide (306) has a portion (316) associated with each fiber bundle leg (304) that is narrower than the fiber bundle leg (304) associated with the portion of the waveguide (306). The reflective bounce plane (312) diverts laser light of the fiber bundle leg (304) that does not travel through the narrow waveguide (306).)

1. A method for welding a plurality of workpieces together along a weld path in a synchronous laser welding system having a plurality of laser delivery beams, wherein each laser delivery beam includes at least one fiber optic beam leg, and a waveguide disposed between the fiber optic beam leg and the plurality of workpieces, the method comprising:

directing laser light from at least one laser source through each fiber bundle leg to a portion of the waveguide associated with that fiber bundle leg;

setting a width of each portion of the waveguide to be narrower than a width of a fiber bundle leg associated with the portion of the waveguide; and

providing a reflective bounce plane for each bundle leg at an exit of the bundle leg, and reflecting a first portion of laser light from each bundle leg with the reflective bounce plane for the bundle leg and causing a second portion of the laser light from the bundle leg to travel through the portion of the waveguide associated with the bundle leg to the weld path to provide a weld where the second portion of the laser light impinges the weld path with a width narrower than a width of the bundle leg.

2. The method of claim 1, wherein advancing the second portion of the laser light from each fiber bundle leg through the portion of the waveguide associated with that fiber bundle leg comprises: homogenizing laser light traveling through the waveguide by the associated portion of the waveguide.

3. The method of claim 1, comprising positioning the fiber optic bundle leg and waveguide to weld the plurality of workpieces together along the weld path with the weld seam, the weld seam being continuous along a weld line.

4. The method of claim 1, comprising positioning the fiber optic bundle leg and waveguide to weld the plurality of workpieces together along the weld path with the weld having a linear weld line.

5. The method of claim 1, comprising positioning the fiber optic bundle leg and waveguide to weld the plurality of workpieces together along the weld path with the weld having a curvilinear weld line.

6. The method of claim 1, comprising positioning the fiber optic bundle leg and waveguide to weld the plurality of workpieces together along the weld path with the weld, the weld being discontinuous along a weld line.

7. The method of claim 1, wherein reflecting the first portion of the laser light through each reflective bounce plane comprises reflecting the first portion of the laser light away from the laser source.

8. A synchronous laser welding system for welding a plurality of workpieces together along a weld path, the synchronous laser welding system comprising:

a laser module having a laser source;

a plurality of laser delivery bundles, wherein each laser delivery bundle comprises at least one fiber bundle leg;

a waveguide having a portion associated with each fiber bundle leg, wherein a width of each portion of the waveguide is narrower than a width of the fiber bundle leg associated with the portion of the waveguide, the waveguide disposed between the plurality of workpieces and the fiber bundle leg;

the fiber-optic-bundle leg extending between the laser module and the waveguide, wherein laser light from the laser source of the laser module is directed through the fiber-optic-bundle leg to the waveguide;

a reflective bounce plane associated with each fiber bundle leg and disposed at an exit of the fiber bundle leg, each reflective bounce plane configured to reflect a first portion of laser light from the fiber bundle leg associated with the reflective bounce plane;

each portion of the waveguide is configured to provide a path through which laser light from a fiber optic bundle leg associated with that portion travels and to direct the laser light to the weld path, wherein a width of a weld at a location where a second portion of the laser light impinges the weld path is narrower than a width of the fiber optic bundle leg.

9. The synchronous laser welding system of claim 8 wherein each section of the waveguide homogenizes laser light traveling through the section.

10. The synchronous laser welding system of claim 8, wherein the weld along the weld path is a continuous weld line.

11. The synchronous laser welding system of claim 8, wherein the weld along the weld path is a linear weld line.

12. The synchronous laser welding system of claim 8 wherein the weld along the weld path is a curvilinear weld line.

13. The synchronous laser welding system of claim 8, wherein the weld along the weld path is a discontinuous weld line.

14. The synchronous laser welding system of claim 8, wherein each reflective bounce plane reflects the laser light away from the laser source.

Technical Field

The present invention relates to plastic welding, and more particularly to providing a narrow weld width along a weld line in plastic welding applications.

Background

This section provides background information related to the present disclosure that is not necessarily prior art.

Laser welding is commonly used to join plastic or resin parts, such as thermoplastic parts, at a weld area.

As is well known, lasers provide a semi-focused beam of electromagnetic radiation (i.e., coherent monochromatic radiation) at a particular frequency. There are many types of radiation sources available. One example of laser welding is infrared transmission (TTIr) welding, which is a preferred technique for welding plastic or resin parts. TTIr welding employs infrared light that passes through a first plastic part and into a second plastic part. In many aspects, tools for TTIr assemblies include a waveguide and fiber optic bundle for directing infrared light from a light source to the plastic parts to be welded. The use of waveguides is common in many cases with TTIr welding methods and other laser welding methods. As is well known, waveguides homogenize infrared light. The width of the weld depends on, among other things, the diameter of the end of the fiber bundle and the internal characteristics of the waveguide, such as the angular slope of the waveguide, the angular spread of the laser light from the fiber, and the thickness of the transmissive part to be welded.

One type of TTIr is synchronous infrared transmission welding, referred to herein as STTIr. In STTIr, the entire welding path or area (referred to herein as the welding path) is simultaneously exposed to laser radiation, such as by coordinated alignment of multiple laser sources, such as laser diodes. An example of STTIr is described in US 6,528,755 "Laser Light Guide for Laser Welding", the entire disclosure of which is incorporated herein by reference. In STTIr, laser radiation is typically transmitted from one or more laser sources to the components being welded through one or more optical waveguides that conform to the contours of the component surfaces being joined along the weld path.

Fig. 1 shows an example of a prior art STTIr laser welding system 100. The STTIr laser welding system 100 includes a laser support unit 102, the laser support unit 102 including one or more controllers 104, an interface 110, one or more power supplies 106, and one or more coolers 108. The STTIr laser welding system 100 may also include an actuator, one or more laser modules (laser banks) 112, and an upper tool/waveguide assembly 35 and a lower tool 20 secured to a support table. Each laser module 112 includes one or more laser channels 113, wherein each laser channel 113 has a laser source 122. The laser support unit 102 is coupled to the actuator and each laser module 112 and provides energy and cooling to the laser module 112 via the power supply(s) 106 and the cooler(s) 108 and controls the actuator and laser module(s) 112 via the controller 104. The actuators are coupled to the upper tool/waveguide assembly 35 and move it to and from the lower tool 20 under the control of the controller 104. In operation, the laser module 112 directs laser energy generated via the laser radiation source through the plurality of laser delivery beams 10. Each laser delivery bundle 10 may be further split into legs, and each leg includes at least one laser delivery fiber. Each laser delivery bundle 10 includes at least one laser delivery fiber if the laser delivery bundle 10 is not split into legs. Each laser delivery fiber delivers laser energy from the laser radiation source of the laser module 112 through the waveguide 30 to a plurality of workpieces 60 to be welded together. The waveguide 30 homogenizes the laser energy delivered to the workpiece 60 by each laser delivery fiber.

In some laser welding applications, the waveguide may be shaped in a linear fashion to receive the dispersed laser light from a series of fiber optic bundles in a row. In some laser welding applications, it is desirable that the width of the waveguide be slender, for example to accommodate workpieces whose shape will block a wider waveguide, or to provide a narrower weld. There is a practical lower limit to the diameter of the fiber bundle. Further, the waveguide has a practical minimum size; that is, the dimensions of the waveguide should be sized to be greater than or equal to the width of the path of the laser light emitted by the fiber optic bundle to prevent the laser light emitted by the fiber optic bundle from spilling over the edges of the waveguide. Furthermore, since the width of the weld is also dependent on the angular spread of the optical fibers, tapering the waveguide does not narrow the final width of the weld in all cases.

In contrast, there is a practical lower limit to how narrow the waveguide can be tapered before the angular spread of the laser increases the effective width of the weld. According to the principle of etendue, the larger the waveguide taper, the larger the angular spread of the laser light. Therefore, there is a practical lower limit to the width of the weld (e.g., the width of the weld, or the width of the length of the weld defined by the path to be welded for multiple workpieces). Reference is made to fig. 2 as an example. On the left side, a weld 202 is shown, where the laser light travels through a fiber bundle leg 204, through a tapered waveguide 206, and through a transmissive plastic part 208 to be welded to an absorptive part 210 to be welded. On the right side, a weld 202 ' is shown, where the laser light travels through the fiber bundle leg 204 ', through the more tapered waveguide 206 ', and through the transmissive plastic part to be welded 208 ' to the absorptive part to be welded 210 '. It should be noted that even though a more tapered waveguide 206 'is used instead of a tapered waveguide 206 as shown in the right drawing, the dimensions of the solder joint 202 and the solder joint 202' are approximately equal. This is because there is a practical lower limit to the width of the weld due to the nature of etendue. In other words, there is a practical lower limit to the weld width that can be achieved by tapering the waveguide. However, in certain applications, it is desirable to provide welds with even narrower weld widths than can be achieved using conventional fiber optic bundles and tapered waveguides.

Disclosure of Invention

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

The present technique provides a method for welding a plurality of workpieces together along a weld path in a synchronous laser welding system having a plurality of laser delivery beams, wherein each laser delivery beam includes at least one fiber optic beam leg, and a waveguide disposed between the fiber optic beam leg and the plurality of workpieces. The method comprises the following steps: laser light from at least one laser source is directed through each fiber bundle leg to a portion of the waveguide associated with the fiber bundle leg, and the width of each portion of the waveguide is set narrower than the width of the fiber bundle leg associated with the portion of the waveguide. The method further comprises the following steps: a reflective bounce plane is provided for each fiber bundle leg at an exit of the fiber bundle leg and a first portion of the laser light from each fiber bundle leg is reflected with the reflective bounce plane for the fiber bundle leg and a second portion of the laser light from the fiber bundle leg is caused to travel through a portion of the waveguide associated with the fiber bundle leg to the weld path to provide a weld where the second portion of the laser light impinges the weld path with a width that is narrower than a width of the fiber bundle leg.

In one aspect, a second portion of the laser light from each fiber bundle leg that passes through the portion of the waveguide associated with that fiber bundle leg is homogenized.

In one aspect, positioning the fiber bundle legs and the waveguides provides a continuous weld line.

In one aspect, positioning the fiber bundle legs and the waveguides provides linear weld lines.

In one aspect, positioning the fiber bundle legs and the waveguides provides a curved weld line.

In one aspect, positioning the fiber bundle legs and the waveguide provides a discontinuous weld line.

In an aspect, reflecting the first portion of the laser light through each reflective bounce plane includes reflecting the first portion of the laser light away from the laser source.

The present technology also provides a synchronized laser welding system for welding a plurality of workpieces together along a welding path. This synchronous laser welding system includes: a laser module having a light source; a plurality of laser delivery bundles, wherein each laser delivery bundle comprises at least one fiber bundle leg; and a waveguide disposed between the fiber bundle leg and the plurality of workpieces. The waveguide has a portion associated with each fiber bundle leg, and the width of each portion of the waveguide is narrower than the width of the fiber bundle leg associated with that portion of the waveguide. A fiber bundle leg extends between the laser module and the waveguide, and laser light from a laser source of the laser module is directed through the fiber bundle leg to the waveguide. A reflective bounce plane is associated with each fiber bundle leg and is arranged at an exit of the fiber bundle leg and is configured to reflect a first portion of the laser light from the fiber bundle leg associated with the reflective bounce plane. Each section of the waveguide is configured to provide a path through which laser light from a fiber optic bundle leg associated with the section travels and to direct the laser light to a weld path, wherein a width of a weld at a location where a second portion of the laser light impinges the weld path is narrower than a width of the fiber optic bundle leg.

In one aspect, each section of the waveguide homogenizes the laser light traveling through that section.

In one aspect, the weld along the weld path is a continuous weld line.

In one aspect, the weld along the weld path is a linear weld line.

In one aspect, the weld seam along the weld path is a curvilinear weld line.

In one aspect, the weld along the weld path is a discontinuous weld line.

In one aspect, each reflective bounce plane reflects laser light away from the laser source.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Drawings

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a schematic diagram illustrating a prior art laser welding system;

FIG. 2 is an enlarged schematic view showing the practical lower limit of the width of the weld that can be achieved by tapering the waveguide;

FIG. 3 is a schematic diagram illustrating an embodiment according to the present disclosure; and

fig. 4 is an enlarged isometric view illustrating an embodiment according to the present disclosure.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Detailed Description

Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that: the exemplary embodiments may be embodied in many different forms without the use of specific details and should not be construed as limiting the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known techniques are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It should also be understood that additional or alternative steps may be employed unless otherwise indicated.

When a component, element, or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another component or layer, it can be directly on and engaged, connected, or coupled to the other component, element, or layer, or intervening components or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to" or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other terms used to describe the relationship between elements (e.g., "between … …" and "directly between … …", "adjacent" and "directly adjacent", etc.) should be interpreted in a similar manner. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and/or sections, these steps, elements, components, regions, layers and/or sections should not be limited by these terms unless otherwise specified. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as "first," "second," and other numerical terms used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.

Spatially or temporally related terms, such as "before", "after", "inside", "outside", "below", "lower", "above", "upper", and the like, may be used herein to facilitate the description of one element or feature's relationship to another element or feature as illustrated in the figures. Spatially and temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.

It will be understood that any recitation of a method, composition, device, or system "comprising" certain steps, ingredients, or features, is also contemplated to, in certain alternative variations, such a method, composition, device, or system may also "substantially comprise" the recited steps, ingredients, or features, to the exclusion of any other steps, ingredients, or features therefrom that may materially alter the basic and novel characteristics of the invention.

Techniques according to the present disclosure provide methods and apparatus for use in simultaneous laser welding applications.

In many aspects, embodiments described according to the present disclosure may be used as part of an STTIr laser welding system, such as the STTIr laser welding system 100 described according to fig. 1.

Turning now to fig. 3, an embodiment in accordance with the present disclosure is shown. In this embodiment, each fiber bundle leg 304 directs laser light from a laser source (such as laser source 122) through a waveguide 306 through a transmissive plastic part 308 to be welded, where the laser light is absorbed by an absorptive plastic part 310 to be welded to form a weld spot 302 at a point along a welding path where the plastic parts are welded together. It should be understood that the weld 302 is formed at each of the following points along the weld path: at these points, laser light from a single fiber bundle leg 304 strikes the weld path after traveling through the waveguide. The welds 302 collectively define a weld line 314 (shown in phantom in FIG. 4) of the weld. As used herein, the term "width" or "weld width" when referring to a weld refers to the width of the weld at any suitable point along a weld line, i.e., the width of the weld across the weld line at any suitable point.

As used herein, the term "fiber bundle leg" means a plurality of laser delivery fibers, and may include a leg having a plurality of laser delivery fibers (such as a leg of a laser delivery bundle) and/or a laser delivery bundle having a plurality of legs and/or having a plurality of laser delivery fibers. It should be understood that in this context, there is a portion 316 of the waveguide 306 associated with each fiber-optic bundle leg 304 (although the portion 316 is illustrated directly in dashed lines in fig. 4, it should be noted that this portion may appear circular, elliptical, or other shape depending on the shape of the waveguide), which is where the laser light from that fiber-optic bundle leg 304 travels through the waveguide 306. When the following discussion refers to the waveguide 306 and associated laser delivery fiber 304, this refers to the portion 316 of the waveguide 306 where laser light from the laser delivery fiber 304 travels through the waveguide 306. It should also be understood that the portion 316 of the waveguide 306 may alternatively be provided by a separate waveguide.

It should be noted that the width of each weld spot 302 is significantly less than the width of the leg portion 304 of the fiber optic bundle that provided the laser light that formed that weld spot 302. This substantially narrowed solder joint 302 is achieved by a portion 316 of the waveguide 306 having a width 320, the width 320 being substantially narrower than a width 322 of the associated fiber-bundle leg 304, such as the diameter of the fiber-bundle leg 304 when the fiber-bundle leg 304 has a circular cross-section such as in the examples of fig. 3 and 4. Since the fiber-optic-bundle leg 304 is wider than the associated portion 316 of the waveguide 306, only a first portion of the laser light exiting the fiber-optic-bundle leg will enter the associated portion 316 of the waveguide 306, and the remaining second portion will overflow the outer edge of the associated portion 316 of the waveguide 306 and not enter the associated portion 316. A reflective bounce plane 312 associated with each fiber bundle leg 304 reflects a first portion of the laser light and a second portion of the laser light travels through an associated portion 316 of the waveguide 306 to a point on a weld path along which the components 308, 310 are welded together and form the weld spot 302. In one aspect, at least one reflective bounce plane is disposed at the exit 318 of each fiber bundle leg 304. In one aspect, reflective bounce planes 312 are disposed at opposite sides 324 of each portion 316 of waveguide 306 such that these reflective bounce planes 312 reflect laser light on opposite sides of weld line 314. In one aspect, the reflective bounce plane 312 is part of the waveguide 306. Opposing sides 324 oppose one another across the width 320 of the portion 316.

The reflective bounce plane 312 preferably comprises a material that reflects, but not absorbs, the laser light used in STTIr applications. Thus, the reflective bounce plane includes a laser mirror, a polished metal surface, and a total internal reflection surface. The reflective bounce plane 312 redirects the laser light away from the parts 308, 312 to be welded to prevent unnecessary welding thereof, and away from the laser source 122 or the fiber-optic bundle leg 304 to avoid damaging the laser system. Generally, a reflective bounce plane 312 is disposed at the end of each fiber bundle leg 304 (e.g., exit 318) and at the entrance of each section 316 of the waveguide 306.

Suitable waveguides according to the present disclosure share two main attributes. First, the width of each portion 316 of the waveguide 306 is narrower than the width of the associated fiber optic bundle leg 304. Second, each section 316 of waveguide 306 must be long enough to homogenize the laser light traveling through section 316 of waveguide 306, thereby allowing for uniform welding. In an example, each portion 316 of the waveguide 306 has a uniform width along its length.

Referring to fig. 4, an alternative view of the embodiment disclosed in fig. 3 is shown. It will be appreciated that in STTIr applications, the plurality of fiber-optic bundle legs 304 simultaneously transmit laser light from the laser source through the associated portion 316 of the waveguide 306 to the components 308, 310 to be welded, which results in a weld zone generally defined by the exit side of the waveguide 306, where the exit side is defined by the side closest to the components 308, 312 facing the components to be welded. Each portion 316 of the waveguide 306 must extend in a vertical direction sufficiently to homogenize the laser light passing through to the parts 308, 310 to be welded.

Further, in STTIr applications, the waveguide may be formed to provide a weld length of any desired or predetermined shape. Thus, although the waveguide 306 is shown as being linear along its length in FIG. 4, it should be understood that the waveguide 306 may be curvilinear. Similarly, although the waveguide 306 is shown as being planar in fig. 4, it should be understood that the waveguide 306 may have any orientation, three-dimensionality, or other twist along the reference plane. It is also contemplated that the waveguide 306 need not have a fixed width throughout the entire waveguide, wherein one or more portions 316 of the waveguide 306 have a different width than one or more of the other portions 316. It is therefore contemplated that the resulting weld line need not have a uniform width, and that the width at a given point along the weld line may depend on the width of the portion 316 of the waveguide 306 adjacent to the given point along the weld line, any resulting angular spread, and the width of the fiber bundle leg 304 at that particular point that is not redirected by the reflective bounce plane 312. Furthermore, the waveguide output shape may be formed as required by welding parameters or preferred conditions, such as a triangle, dot, or blob.

The waveguides may be positive or negative waveguides or any combination of the two. Positive waveguides use a solid medium that can transmit laser light and guide the light by total internal reflection. The negative waveguide guides the laser light by vacuum, gas, liquid or solid transmission but by means of reflective walls.

As described above, the above-described techniques are suitable for use as part of an STTIr laser welding system, such as the STTIr laser welding system 100 shown in fig. 1. In such a modified STTIr system, it is contemplated that fiber optic bundle leg 304 will replace the leg of laser delivery bundle 10, and waveguide 306 and reflective bounce plane 312 will replace waveguide 30. Such an improved STTIr system would provide a significantly narrower weld width than is possible with conventional STTIr systems using similarly sized fiber bundle legs. It is also contemplated that in such a system, the laser applied to the parts to be welded will result in a weld length having a weld width that is significantly less than would be possible with a conventional STTIr system. And as described above, depending on the parameters of the waveguide 306, the resulting weld line may be produced in a variety of forms including linear, curvilinear, continuous, discontinuous, with a twist, and exhibiting a three-dimensional weld length. According to another aspect, such a weld line may be manufactured using a waveguide shaped to produce a desired shape, such as a triangle, dot, or blob. According to yet another aspect, the width of the weld line may vary along the path of the weld line to the extent that the width of the waveguide and/or the corresponding reflective bounce plane vary along the waveguide.

The foregoing description of embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The particular embodiments may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.