Patent Application
20200189204
The present disclosure relates to laser welding.
This section provides background information related to the present disclosure which is not necessarily prior art.
Trace laser welding and scanning laser welding are commonly used to weld clear plastic parts together. A spot laser tracks a weld path by movement of the laser device and/or laser beam, work piece, or a combination thereof. Trace laser welding systems use a movable frame to which the laser light source is mounted, such as a gantry, to move the laser beam and scan laser welding systems use a Galvo mirror to move the laser beam. However, the term “trace laser welding” in the context of laser welding systems is sometimes broadly used for both types of laser welding system and as used herein has this broader meaning.
Because the clear plastic part absorbs the two micron laser beam volumetrically, when radiating a spot along the weld path with a single laser beam if the intensity of the laser beam is high enough to melt the clear plastic part, the intensity is too high for the laser beam to penetrate through any substantial volume of material of the clear plastic part. Thus, the weld will be a surface weld. Further the clear plastic part through which the laser light travels therefore has to be fairly thin. Thus, true 3D welds inside a volume are not practically feasible with the aforementioned trace laser welding. It is thus an object of the present disclosure to provide laser welding that can weld clear plastic parts together with true 3D volumetric welds.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Plastic parts are welded in a laser welding system in accordance with one or of the below described aspects. At least one of the plastic parts is a partially absorptive plastic part that is partially absorptive to laser light at an absorption wavelength.
In an aspect, the plastic parts are welded in an intersecting multi-beam laser welding system having at least two trace laser welding subsystems. Each trace laser welding system includes a laser that generates a laser beam having the absorption wavelength. The trace laser welding subsystems are configured to direct their laser beams to the plastic parts so that they intersect each other at a point along a weld path within the partially absorptive plastic part at an angle in an intersection angle range between ten degrees and ninety degrees. Each trace laser welding subsystem is configured so that its laser generates its laser beam at an intensity that is lower than an intensity that will cause a material of which the partially absorptive plastic part is made to reach a melting temperature and an intensity high enough so that an intensity of laser energy at the intersection of laser beams is high enough to cause the material of which the partially absorptive plastic part is made to reach a melting temperature and melt.
In an aspect, the trace laser welding subsystems are configured to trace their respective laser beams so that the intersection of the laser beams traces around the weld path.
In an aspect, each trace laser welding subsystem includes a galvanometer mirror that traces the laser beam.
In an aspect, each trace laser welding subsystem includes a movable frame to which a laser light source that generates the laser beam is affixed that is moved to trace the laser beam.
In an aspect, one of the trace laser welding subsystems includes a galvanometer mirror that traces the laser beam and another one of the trace laser welding system includes a movable frame to which a laser light source that generates the laser beam is affixed that is moved to trace the laser beam.
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.
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.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example 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 who are skilled in the art. Numerous specific details are set forth such as examples of specific 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 specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies 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” may be 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 is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements 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 words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). 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 elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In accordance with an aspect of the present disclosure, plastic parts are welded with a true 3D volumetric weld using intersecting multi-beam trace laser welding in which a plurality of spot laser beams having the same wavelength are directed to the parts so that the laser beams intersect each other at a point along a weld path within one of the plastic parts at an angle in an intersection angle range between ten degrees and ninety degrees. The plurality of laser beams are traced so that the intersection of the plurality of laser beams traces along the weld path to form a weld pattern that is linear, curvilinear, planar or three dimensional along a joint that is inside a volume of plastic.
The plastic part in which the laser beams intersect is partially absorptive to laser light at a wavelength and the laser beams have this wavelength. This plastic part in which the laser beams intersect may be referred to herein as the partially absorptive plastic part. The wavelength at which the partially absorptive material of the partially absorptive plastic part is partially absorptive to laser light may sometimes be referred to herein as the absorption wavelength. It should be understood that the partially absorptive part is only partially absorptive to the laser light and not fully absorptive. Illustratively, the partially absorptive plastic part has an absorptivity in the range of fifteen percent to eighty percent. Illustratively, this absorption wavelength is two microns as polymers generally are partially absorptive to laser light at a wavelength around two microns. It should be understood that this absorption wavelength can be other than two microns and is dependent on the material of which the partially absorptive plastic part in which the laser beams intersect is made. It should be understood that the other part can also be partially absorptive to laser light at the absorption wavelength, but also can be transmissive or opaque to laser light at the absorption wavelength. It should be understood that the plastic parts may be clear to the eye, tinted, opaque the eye, but at least one of the parts is partially absorptive to laser light at the absorption wavelength.
The intensity of each laser beam is below an intensity that causes the polymer of the partially absorptive plastic part to melt. At the point where the laser beams intersect, the intensity is at or above the intensity that causes the polymer of the partially absorptive plastic part to melt. The laser beams intersect at an angle in an intersection angle range between ten degrees and ninety degrees. This angle at which they intersect each other is for example determined heuristically to melt a desired portion of the partially absorptive clear plastic part where the laser beams intersect. It should be understood that more than two intersecting laser beams can be used and the angle between any two intersecting laser beams determined as described above. In an aspect, the parts are clear plastic parts meaning that they are clear to the eye (that is, clear in the visible spectrum).
It should be understood that partially absorptive plastic part 202 can be made of material that is partially absorptive to laser light at an absorption wavelength other than two microns. In which case, laser beams 212 will have this absorption wavelength.
Controller 210 can be or includes any of a digital processor (DSP), microprocessor, microcontroller, or other programmable device which are programmed with software implementing the above described logic. It should be understood that alternatively it is or includes other logic devices, such as a Field Programmable Gate Array (FPGA), a complex programmable logic device (CPLD), or application specific integrated circuit (ASIC). When it is stated that controller 210 performs a function or is configured to perform a function, it should be understood that controller 210 is configured to do so with appropriate logic (such as in software, logic devices, or a combination thereof). When it is stated that controller 210 has logic for a function, it should be understood that such logic can include hardware, software, or a combination thereof.
The foregoing description of the embodiments has been provided 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 same 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.
This application claims the benefit of U.S. Provisional Application No. 62/507,268 filed on May 17, 2017. The entire disclosure of the above application is incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/029286 | 4/25/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62507268 | May 2017 | US |
