WO2018212947A1

WO2018212947A1 - Simultaneous laser welding using two-micron laser light

Info

Publication number: WO2018212947A1
Application number: PCT/US2018/029264
Authority: WO
Inventors: Scott Caldwell
Original assignee: Branson Ultrasonics Corp
Current assignee: Branson Ultrasonics Corp
Priority date: 2017-05-17
Filing date: 2018-04-25
Publication date: 2018-11-22
Anticipated expiration: 2019-11-17

Abstract

Plastic parts are welded in a laser welding system. 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 a range of 1.6 microns to 2.4 microns. In an aspect, the plastic parts are welded in a two-micron simultaneous laser welding system in which the plastic parts are received. In an aspect, the plastic parts are welded in an intersecting multi-beam laser welding that includes a two-micron simultaneous laser welding subsystem and a second laser welding subsystem. In an aspect, the second laser welding subsystem is a two-micron simultaneous laser welding subsystem. In an aspect, the second laser welding subsystem includes one or more trace laser welding subsystems.

Description

SIMULTANEOUS LASER WELDING USING TWO-MICRON LASER LIGHT

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/507,264 filed on May 17, 2017. The entire disclosure of the above application is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to laser welding.

BACKGROUND

[0003] This section provides background information related to the present disclosure which is not necessarily prior art.

[0004] Two-micron scan or trace laser welding systems for welding clear to clear plastic are known in the art. As used herein, clear means that the plastic is clear to the eye - transmissive in the visible spectrum. However, the plastic is substantially absorptive to laser light at a wavelength of around 2 microns. Because the plastic is a substantive volumetric absorber of the laser light at this wavelength, the laser light cannot penetrate far into the plastic if the laser light has an intensity sufficient to melt the plastic. Therefore, the weld interface cannot be far from an input surface of the first part that the laser light impacts, which requires that this first part be thin. Such scan or trace laser welding systems typically use a two-micron fiber laser as the source of the laser light that provides a good columnar beam that is well suited for scanning or tracing.

[0005] Through transmission infrared welding (TTIr) systems for welding plastic parts together are also known in the art. In TTIr welding, a transmissive plastic part and an absorptive plastic part are held together with a force with abutting surfaces at a weld interface in good contact with each other. Infrared laser light at a suitable infrared wavelength (980 nano-meters or 808 nano-meters for example) is directed to the parts being welded. This laser light passes through the transmissive part and impacts the absorptive plastic part at the weld interface and gets converted to heat by absorption by the absorptive part. This heats the absorptive plastic part at the weld interface which is heated above a melting temperature. As the absorptive plastic part melts, the heat is transferred across the weld interface to the transmissive part melting the transmissive part at the weld interface forming a molten weld at the weld interface. Once the laser is turned off, the molten weld solidifies welding the parts together at the weld interface.

[0006] In order for clear-to-clear plastic parts to be welded with TTIr laser welding, an absorptive compound that is clear to the eye and absorptive to the laser light has to be either placed at the weld interface, or has to be blended into the absorptive plastic part.

[0007] There are five general types of known TTIR laser welding systems. One such system uses a scanning laser. Another such system uses a tracing laser. A third such system uses a diffraction pattern to deliver a simultaneous laser weld pattern. A fourth such system simultaneously delivers laser light through waveguides, lightpipes and/or fiber optics to simultaneously illuminate the entire weld pattern and is known as simultaneous through transmission infrared (STTIr) laser welding. Such a SSTIr system is available from Branson Ultrasonics Corporation and an example of STTIr is described in US 6,528,755 for "Laser Light Guide for Laser Welding," the entire disclosure of which is incorporated herein by reference. The fifth type of TTIr laser welding system simultaneously illuminates the entire weld pattern directly from multiple laser diodes.

[0008] It should be understood that while 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 scanning laser welding systems use a Galvo mirror to move the laser beam, the term "trace laser welding" in the context of a laser welding system is sometimes broadly used to refer to both types of laser welding systems and as used herein has this broader meaning. Fig. 1A shows an example of a prior art STTIr laser welding system 100. STTIr laser welding system 100 includes a laser support unit 102 including one or more controllers 104, an interface 109, one or more power supplies 106, and one or more chillers 108. SSTIr laser welding system 100 also includes an actuator 1 10, one or more laser banks 1 12, an upper tool/waveguide assembly 1 14 and a lower tool 1 16 fixtured on a support table 1 18. Laser support unit 102 is coupled to actuator 1 10 and each laser bank 1 12 and provides power and cooling via power supply (or supplies) 106 and chiller (or chillers) to 108 to laser banks 1 12 and controls actuator 1 10 and laser banks 1 12 via controller 104. Actuator 1 10 is coupled to upper tool/waveguide assembly 1 14 and moves it to and from lower tool 1 16 under control of controller 104.

[0009] As best shown in Fig. 1 B, each laser bank 1 12 includes one or more channels 122 with each channel 122 having a laser 124, which may illustratively include a laser diode that emits laser light at the infrared wavelength discussed above. Each channel 122 is coupled by a fiber bundle 126 to a waveguide 128 of upper tool/waveguide assembly 1 14. Waveguide 128 is fixtured in an upper tool 130 of upper tool/waveguide assembly 1 14. Each fiber bundle 126 splits into one or more legs 132 with each leg terminating in a ferrule 134 at waveguide 128. (For clarity of Fig. 2, only two ferrules 134 are identified by reference number 134 in Fig. 2.) While not shown in Fig. 2B for clarity of Fig. 2B, it should be understood that there would be sufficient laser banks 1 12 with associated channels 122, fiber bundles 126 and legs 132 terminating in ferrules 134 so that there would ferrules 134 around the entire weld path defined by waveguide 128, such as around the entire periphery of waveguide 128, sufficient to radiate the entire weld path of parts 138, 140 being welded with laser light. Each laser channel 122 is controlled by controller 104. It should be understood that each leg 132 typically has several fibers that are part of one of the fiber bundles 126 so that each ferrule is fed laser energy by these several fibers of the associated fiber bundle 126 from the laser 124 of the laser channel 122 to which the leg is coupled via the associated fiber bundle 126.

[0010] In contrast to scan or trace laser welding in which two-micron laser light has been used to weld clear to clear plastic, two-micron laser light has not been used in simultaneous laser welding to weld plastic parts together including clear to clear plastic parts. One reason is that two-micron fiber lasers that are used as the source of two- micron laser light in scan or trace laser welding to weld clear to clear plastic are quite expensive and simultaneous laser welding typically requires many laser light sources.

SUMMARY

[0011] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0012] Plastic parts are welded in a laser welding system in accordance with one or more 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 a range of 1 .6 microns to 2.4 microns.

[0013] In an aspect, the plastic parts are welded in a two-micron simultaneous laser welding system in which the plastic parts are received. The simultaneous laser welding system includes a plurality laser light sources wherein each laser light source generates a laser beam having the absorption wavelength. A fiber bundle is associated with each laser light source wherein the fiber bundles are disposed to direct the laser beams from the laser light sources to a weld path at a weld interface at which the parts are welded together to simultaneously illuminate the entire weld path with laser light having the absorption wavelength.

[0014] In an aspect, the plastic parts are welded in an intersecting multi-beam laser welding system in which the plastic parts are received. The intersecting multi- beam laser welding system includes a first laser welding subsystem and a second laser welding subsystem. The first laser welding subsystem is a two-micron simultaneous laser welding subsystem that includes a first set of first laser light sources wherein each laser light source generates a first laser beam having the absorption wavelength. The first laser welding subsystem also includes a plurality of first fiber bundles wherein each of the first fiber bundles is associated with a different one of each of the first laser light sources wherein the first fiber bundles are disposed to direct the first laser beams from the first laser light sources to a weld path within the partially absorptive plastic part to simultaneously illuminate the entire weld path with laser light from the first laser light sources having the absorption wavelength. The second laser welding subsystem has at least one second laser light source that generates at least one second laser beam having the absorption wavelength and directs the second laser beam to the weld path so that it intersects at the weld path at least one of the first laser beams at an angle in an intersection angle range between ten degrees and ninety degrees. The first and second laser welding subsystems are configured so that their respective first and second laser light sources generate their respective laser beams 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 the second laser beam with each first laser beam at the weld path is high enough to cause the material of which the partially absorptive plastic part is made to reach a melting temperature and melt. [0015] In an aspect, the second laser welding subsystem is also a two-micron simultaneous laser welding subsystem having a second set of the second laser light sources that generate a plurality of the second laser beams. It also has a plurality of second fiber bundles wherein each of the second fiber bundles is associated with a different one of each of the second laser light sources wherein the second fiber bundles are disposed to direct the second laser beams from the second laser light sources to the weld path at the weld interface to simultaneously illuminate the entire weld path with laser light from the second laser sources having the absorption wavelength. The first and second fiber bundles are disposed so that corresponding ones of the first and second laser beams intersect each other at the weld path at an angle in the intersection angle range.

[0016] In an aspect, the second laser welding subsystem of the intersecting multi-beam laser welding system is a trace laser welding subsystem configured to generate the second laser beam with the second laser light source and direct the second laser beam to the weld path by tracing the second laser beam around the weld path so that it intersects each of the first laser beams at an angle in the intersection angle range as it is traced around the weld path.

[0017] In an aspect, the second laser welding subsystem of the intersecting multi-beam laser welding system includes a plurality of trace laser welding subsystems that generate a plurality of the second laser beams with each trace laser welding subsystem configured to generate one of the plurality of second laser beams,. The plurality of second trace laser welding subsystems are configured to direct their respective second laser beam to the weld path so that it intersects each of the first laser beams at an angle in the intersection angle range as it is traced around the weld path.

[0018] In an aspect, the trace laser welding subsystems are configured to trace their respective second laser beams around the weld path so that they also intersect each other at an angle in the intersection angle range as they are traced around the weld path.

[0019] 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

[0020] 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.

[0021] Fig. 1A is a diagrammatic view of an example of a prior art simultaneous through transmissive infrared laser welding system;

[0022] Fig. 1 B is a diagrammatic view of a laser bank of the laser welding system of Fig. 1A;

[0023] Fig. 2A is a diagrammatic view of a two-micron simultaneous laser welding system in accordance with an aspect of the present disclosure;

[0024] Fig. 2B is a diagrammatic view of a laser bank of the laser welding system of Fig. 2A;

[0025] Fig. 3 is a diagrammatic view of a multi-beam two-micron simultaneous laser welding system in accordance with an aspect of the present disclosure; and

[0026] Figs. 4A - 4C are diagrammatic views of a multi-beam two-micron laser welding system having a two-micron simultaneous laser welding system and a two- micron trace laser welding system in accordance with an aspect of the present disclosure.

[0027] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0028] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0029] 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. [0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] In accordance with an aspect of the present disclosure, plastic parts are welded by two-micron simultaneous laser welding in which a weld pattern around a weld interface between the parts being welded together is simultaneously radiated with a plurality of two-micron laser beams. As used herein a "two-micron" laser beam is a beam of laser light having a wavelength in the range of 1 .6 microns to 2.4 microns. The specific wavelength is selected based on the absorptivity of the fully or partially absorptive plastic part. That is, the specific wavelength is selected so that the fully or partially absorptive plastic part has a requisite degree of absorptivity at the specific wavelength. In this regard, the wavelength of the laser beam is selected so that the full or partially absorptive plastic part will have an absorptivity in the range of 30% to 100% at the specific wavelength of the laser light being used. In an aspect, the laser light of the two-micron laser beams is delivered through waveguides, lightpipes and/or fiber optics to simultaneously illuminate the entire weld pattern.

[0035] In an aspect, plastic parts are welded with a true 3D volumetric weld using multi-beam two-micron simultaneous laser welding. In this aspect, the partially absorptive plastic part can have a lower absorptivity to laser light and the wavelength of the laser beam is selected so that the partially absorptive plastic part will have an absorptivity in the range of 15% to 80% at the specific wavelength of the laser light being used. As used herein, in multi-beam two-micron simultaneous laser welding, at least one other two-micron laser beam is directed to the parts being welded from a direction different than directions at which laser beams of the two-micron simultaneous laser welding are directed at the parts so that it intersects each laser beam of the two- micron simultaneous laser welding at a point on a weld path within one of the plastic parts. In an aspect, this one other two-micron laser beam is scanned or traced so that it intersects the laser beams of the two-micron simultaneous laser welding as it moves 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. In an aspect, the at least one other two-micron laser beam is a plurality of two-micron laser beams.

[0036] The plastic part in which the one other two-micron laser beam intersects the two-micron laser beams of the two-micron simultaneous laser welding is partially absorptive to laser light at the two-micron wavelength and the laser beams of the two- micron simultaneous laser welding and the at least one other two-micron laser beam have this wavelength. The wavelength at which the partially absorptive material is partially absorptive to laser light may sometimes be referred to herein as the absorption wavelength. 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 of the two-micron simultaneous laser welding and of the at least one other two-micron laser beam is below an intensity that causes the polymer of the partially absorptive clear plastic part to melt. At the points where the at least one other two-micron laser beam intersects the two-micron laser beams of the two-micron simultaneous laser welding, the intensity is at or above the intensity that causes the polymer of the partially absorptive clear plastic part to melt. The at least one other two-micron laser beam intersects each of the two-micron laser beams of the two-micron simultaneous laser welding at an angle greater than zero degrees and less than one-hundred eighty degrees. This angle is for example determined heuristically to melt a desired portion of the partially absorptive clear plastic part where the at least one other two-micron laser beam intersects each of the two-micron laser beams of the two-micron simultaneous laser welding It should be understood that a plurality of other two-micron laser beams can be used. In an aspect, the plurality of other two-micron laser beams are traced to intersect the two-micron laser beams of the two-micron simultaneous laser welding.

[0037] Fig. 2A shows a two-micron simultaneous laser welding system 200 in accordance with an aspect of the present disclosure and Fig. 2B shows a laser bank 212 of two-micron simultaneous laser welding system 200. Two-micron simultaneous laser welding system 200 is essentially the same as SSTIr laser welding system 100 with the exception of each laser channel 222 that has a two-micron laser diode 224. That is, laser diode 224 generates a two-micron laser beam instead of a laser beam having the wavelength of the laser beam generated by laser 124 of laser bank 1 12, which is less than one micron, typically 980 nm or 808 nm, as discussed above.

[0038] In operation, parts 238, 240 are received in two-micron simultaneous laser welding system 200, such as in upper tool/waveguide assembly 1 14 and lower tool 1 16. The parts 238, 240 are brought together and held against each other with a force, such as by actuator 1 10 controlled by controller 104 of laser support unit 102 moving upper tool/waveguide to lower tool 1 16. Laser diodes 224 are energized, such as by controller 104 controlling laser channels 222 to energize laser diodes 224. The laser beams generated by the laser diodes 224 are directed to parts 238, 240, such as through fiber bundles 126 and waveguide 128 and simultaneously illuminate the entire weld path 228 along weld interface 229 with two-micron laser light. The controller 104 controls laser channels 222 to maintain the laser diodes 224 energized until active welding is completed at which time the controller 104 controls the laser channels 222 to de-energize the laser diodes 224. After a period of time, the controller 104 controls actuator 1 10 to move upper tool/waveguide assembly 1 14 away from lower tool 1 16 and parts 138, 140 that have been welded together can be removed from two-micron simultaneous laser welding system 200.

[0039] As discussed above, two-micron laser light as used herein is laser light having a wavelength in the range of 1 .6 microns to 2.4 microns. The specific wavelength of the laser light is selected so that the partially absorptive plastic part, such as plastic part 240, has a requisite degree of absorptivity to the laser light that it is irradiated with. In this regard, it should be understood that this is dependent on the material(s) of which the partially absorptive plastic part is made.

[0040] Fig. 3 is a simplified diagrammatic view of an intersecting multi-beam two- micron simultaneous laser welding system 300 in accordance with an aspect of the present disclosure for welding clear plastic parts 302, 304. As used herein, intersecting multi-beam means that at least two laser beams intersect each other at a weld path 314 along weld path 315 within a partially absorptive plastic part 302 of plastic parts being welded together at an angle in an intersection angle range between ten degrees and ninety degrees. [0041] Intersecting multi-beam two-micron simultaneous laser welding system 300 includes a plurality of two-micron simultaneous laser welding subsystems with each illustratively being a two-micron simultaneous laser welding system 200 and referred to in this context as two-micron simultaneous laser welding subsystems 200. Two-micron simultaneous laser welding subystems 200 have respective laser banks 306, 308 which may each illustratively be a laser bank 212 (Fig. 2B). Each laser bank 306, 308 includes a plurality of laser channels (not shown in Fig. 3) which may each illustratively be a laser channel 222 (Fig. 2) with each laser channel 222 having a two-micron laser diode 224. It should be understood that each laser bank 306, 308 may be a plurality of laser banks 212 depending on how many laser beams are needed to simultaneously expose all of weld path 314 to laser light from each laser bank 306, 308. A fiber bundle 126 is associated with each laser channel 222. Laser bank 306 generates a plurality of two-micron laser beams 310 and laser bank 308 generates a plurality of two-micron laser beams 312 with each two-micron laser beam 310 and a corresponding one of two-micron laser beams 312 intersecting the partially absorptive plastic part 302 from different directions so that they intersect each other at the angle in the intersection angle range at a desired point of the weld path within the partially absorptive plastic part where. In this regard, the fiber bundles 126 are disposed so that they direct the respective two-micron laser beams 310, 312 to intersect in this manner. The intersection of the plurality of two-micron laser beams 310 with the plurality of two- micron laser beams 312 along weld path 314 within partially absorptive plastic part 302 forms a true 3D volumetric weld 316 - a weld in which the weld melt originates in a volume of the partially absorptive plastic part 302 inside partially absorptive plastic part 302 and propagates to the other plastic part 304 to melt a portion of the other plastic part 304 together with the melted portion of partially absorptive plastic part 302.

[0042] Each controller 104 controls the laser channels in the laser bank 306, 308 that it controls so that each two-micron laser beam 310, 312 has an intensity that is less than an intensity that will cause the material of which partially absorptive plastic part 302 is made to reach a melting temperature. The intensity of laser energy where the two-micron laser beams 310, 312 intersect along weld path 314 is at or above an intensity that causes the material of which partially absorptive plastic part 302 is made to reach a melting temperature and melt. [0043] In a variation, an intersecting multi-beam two-micron laser welding system has a two-micron simultaneous laser welding and trace laser welding that weld plastic parts 302, 304 together with a true 3D volumetric weld. That is, the two-micron simultaneous laser welding provides at least one set of multiple laser beams that simultaneously expose the entire weld path to two laser light. The trace laser welding provides at least one two-micron laser beam that intersects each of the two-micron laser beams of the two-micron simultaneous laser welding as that two-micron laser beam of the trace laser welding system traces around the weld path. The two-micron laser beam of the trace laser welding intersects each two-micron laser beam of the simultaneous laser welding as the two-micron laser beam of the trace laser welding traces around the weld path at the angle in the intersection angle range at a desired point on the weld path within the partially absorptive plastic part. It should be understood that the intersecting angles at which the two-micron laser beam of the trace laser welding intersects each of the two-micron laser beams of the simultaneous laser welding can be the same, can be different from each other, or some can be the same and others be different. In an aspect, the laser beam provided by trace laser welding is moved by a Galvo mirror. In an aspect, the laser beam provided by trace laser welding is moved by a movable frame to which the laser that generates the laser beam is attached.

[0044] Figs. 4A - 4C are simplified diagrammatic views of intersecting multi- beam two-micron laser welding systems 400, 400,' 400" that are hybrid intersecting multi-beam two-micron laser welding systems having two-micron simultaneous laser welding and trace laser welding. Referring first to Fig. 4A, hybrid intersecting multi- beam two-micron laser welding system 400 has at least one two-micron-simultaneous laser welding subsystem 200 and at least one two-micron trace laser welding subsystem 402. Two-micron simultaneous laser welding subsystem system 200 includes a laser bank 306 that may illustratively be a laser bank 212 that includes a plurality of laser channels (not shown in Fig. 4A) which may each illustratively be a laser channel 222 (Fig. 2) with each laser channel 222 having a two-micron laser diode 224. Laser bank 306 may be a plurality of laser banks 212 depending on how many laser beams are needed to simultaneously expose all of weld path 314 to laser light from laser bank 306. Laser bank 306 generates a plurality of two-micron laser beams 310 that contact weld path 314 to simultaneously expose all of weld path 314 to laser light from laser bank 306. Laser welding system 400 also includes at one two-micron trace laser welding subsystem system 402 that includes at least one two-micron trace laser 404 that generates a two-micron laser beam 406, illustratively with a two-micron laser diode. Two-micron trace laser welding subsystem system 402 includes a laser support unit 102' configured to support and control trace laser welding subsystem system 402 and two-micron simultaneous laser welding subsystem system 200 includes laser support unit 102 configured to support and control two-micron simultaneous laser welding subsystem 402. It should be understood that laser support unit 102' is essentially the same as laser support unit 102 but configured for control of two-micron trace laser welding subsystem 402 instead of two-micron simultaneous laser welding subsystem 200.

[0045] Two-micron trace laser welding subsystem 402 includes a Galvo mirror 408 associated with laser 404. The controller (not shown in Fig. 4A) of laser support unit 102' that controls two-micron trace laser welding subsystem 402 is configured to control Galvo mirror 408 to move the laser beam 406 generated by the laser 404 with which Galvo mirror 408 is associated so that laser beam 406 traces along weld path 314 and intersects the individual laser beams 310 from laser bank 306 as it does so. In laser welding system 400' shown in Fig. 4B, laser 404 is affixed to a movable frame 410 and the controller of laser support unit 102" that controls two-micron trace laser welding subsystem 402" is configured to control the movement of movable frame 410 so that the laser beam 406 generated by laser 404 traces along weld path 314 and intersects the individual laser beams 310 from laser bank 306 as it does so. It should be understood that laser support unit 102" is essentially the same as laser support unit 102' but configured to control two-micron trace laser welding subsystem 402" and movable frame 410 thereof instead of two-micron trace laser welding subsystem 402' and Galvo mirror 408 thereof.

[0046] With reference to Fig. 4C, at least two crossing two-micron laser beams 406 are provided by two-micron trace laser welding subsystems 402, 402' and at least one set of multiple two-micron laser beams provided by two-micron simultaneous laser welding subsystem 200. The two-micron simultaneous laser welding subsystem 200 provides at least one set of multiple laser beams 310 that simultaneously expose the entire weld path 314 to laser light from laser bank 306. The two crossing laser beams 406 intersect the weld path 314 from directions that are different from each other and also different from directions that the multiple laser beams 310 intersect weld path 314. Intersecting multi-beam two-micron laser welding system 400" has at least at least one crossing two-micron laser beam 406 that is moved by a Galvo mirror 408 associated with a laser 404, another crossing two-micron laser beam 406 is moved by movement of movable frame 410 to which the Iaser404 that generates that laser beam 406 is affixed, and the at least one laser bank 306 generates a plurality of laser beams 310 that simultaneously expose all of weld path 314 to laser light from laser bank 306.

[0047] Controller 104 of each laser support unit 102 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 104 performs a function or is configured to perform a function, it should be understood that controller 104 is configured to do so with appropriate logic (such as in software, logic devices, or a combination thereof). When it is stated that controller 104 has logic for a function, it should be understood that such logic can include hardware, software, or a combination thereof.

[0048] 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.

Claims

CLAIMS What is claimed is:

1 . A method of laser welding a plurality of plastic parts together; comprising: providing as at least one of the plastic parts a plastic part that is a partially absorptive plastic part that is partially absorptive to laser light at an absorption wavelength in a range of 1 .6 microns to 2.4 microns, comprising:

holding the plastic parts together in a simultaneous laser welding system; and generating a first set of a plurality of laser beams having the absorption wavelength with a first set of a plurality of laser light sources of the simultaneous laser welding system; and

directing the plurality of laser beams to a weld path at a weld interface at which the parts are welded together to simultaneously illuminate the entire weld path with laser light having the absorption wavelength.

2. A method of laser welding a plurality of plastic parts together; comprising: providing as at least one of the plastic parts a plastic part that is a partially absorptive plastic part that is partially absorptive to laser light at an absorption wavelength in a range of 1 .6 microns to 2.4 microns, comprising:

holding the plastic parts together in a laser welding system; and

generating a first set of a plurality of first laser beams having the absorption wavelength with a first set of a plurality of first laser light sources of the laser welding system and directing the plurality of first laser beams to a weld path within the partially absorptive plastic part to simultaneously illuminate the entire weld path with laser light of the first laser beams having the absorption wavelength;

generating at least one second laser beam having the absorption wavelength with a second laser light source of the laser welding system;

directing the second laser beam to the weld path so that at the weld path the second laser beam intersects at least one of the first laser beams at an angle in an intersection angle range between ten degrees and ninety degrees; and

wherein generating the laser beams includes generating them to have 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 at the weld path is high enough to cause the material of which the partially absorptive plastic part is made to reach a melting temperature and melt.

3. The method of claim 2 wherein generating the at least one second laser beam includes generating a second set of a plurality of the second laser beams with a plurality of second laser light sources with each second laser beam having the absorption wavelength and directing the plurality of second to the weld path within the partially absorptive plastic part to simultaneously illuminate the entire weld path with laser light of the second laser beams having the absorption wavelength; and directing the first and second laser beams to the weld path so that corresponding ones of the first and second laser beams intersect each other at the weld path at the angle in the intersection angle range.

4. The method of claim 2 wherein generating the second laser beam includes generating the second laser beam as a trace laser beam and directing the second laser beam to the weld path includes tracing the second laser beam around the weld path so that the second laser beam intersects each of the first laser beams at the angle in the intersection angle range as the second laser beam is traced around the weld path.

5. The method of claim 2 wherein generating the second laser beam includes generating a plurality of second laser beams as trace laser beams and directing the second laser beams to the weld path includes tracing the second laser beams around the weld path so that the second laser beams intersect each of the first laser beams at the angle in the intersection angle range as the second laser beams are traced around the weld path.

6. The method of claim 5 wherein tracing the second laser beams around the weld path includes tracing them around the weld path so that the second laser beams also intersect each other at the angle in the intersection angle range as they are traced around the weld path.

7. A simultaneous laser welding system for welding together a plurality of plastic parts received in the simultaneous laser welding system wherein 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 a range of 1 .6 microns to 2.4 microns, comprising: a plurality of laser light sources wherein each laser light source generates a laser beam having the absorption wavelength; and

a fiber bundle associated with each laser light source wherein the fiber bundles are disposed to direct the laser beams from the laser light sources to a weld path at a weld interface at which the parts are welded together to simultaneously illuminate the entire weld path with laser light having the absorption wavelength.

8. An intersecting multi-beam laser welding system for welding together a plurality of plastic parts received in the laser welding system wherein 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 a range of 1 .6 microns to 2.4 microns, comprising:

a first laser welding subsystem that is a two-micron simultaneous laser welding subsystem, the two-micron simultaneous laser welding subsystem including:

a first set of first laser light sources wherein each laser light source generates a first laser beam having the absorption wavelength;

a plurality of first fiber bundles wherein each of the first fiber bundles is associated with a different one of each of the first laser light sources wherein the first fiber bundles are disposed to direct the first laser beams from the first laser light sources to a weld path within the partially absorptive plastic part to simultaneously illuminate the entire weld path with laser light from the first laser light sources having the absorption wavelength; and

a second laser welding subsystem having at least one second laser light source that generates at least one second laser beam having the absorption wavelength and directs the second laser beam to the weld path so that the second laser beam intersects at the weld path at least one of the first laser beams at an angle in an intersection angle range between ten degrees and ninety degrees; and the first and second laser welding subsystems configured so that their respective first and second laser light sources generate their respective laser beams 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 the second laser beam with each first laser beam at the weld path is high enough to cause the material of which the partially absorptive plastic part is made to reach a melting temperature and melt.

9. The laser welding system of claim 8 wherein the second laser welding subsystem is also a two-micron simultaneous laser welding subsystem having:

a second set of the second laser light sources that generate a plurality of the second laser beams;

a plurality of second fiber bundles wherein each of the second fiber bundles is associated with a different one of each of the second laser light sources wherein the second fiber bundles are disposed to direct the second laser beams from the second laser light sources to the weld path at the weld interface to simultaneously illuminate the entire weld path with laser light from the second laser sources having the absorption wavelength; and

the first and second fiber bundles are disposed so that corresponding ones of the first and second laser beams intersect each other at the weld path at the angle in the intersection angle range.

10. The laser welding system of claim 8 wherein the second laser welding subsystem is a trace laser welding subsystem configured to generate the second laser beam with the second laser light source and direct the second laser beam to the weld path by tracing the second laser beam around the weld path so that the second laser beam intersects each of the first laser beams at the angle in the intersection angle range as it is traced around the weld path.

1 1 . The laser welding system of claim 10 wherein the second laser subsystem includes a plurality of trace laser welding subsystems that generate a plurality of the second laser beams with each trace laser welding subsystem configured to generate one of the plurality of second laser beams, the plurality of second trace laser welding subsystems configured to direct their respective second laser beam to the weld path so that the respective second laser beam intersects each of the first laser beams at the angle in the intersection angle range as that second laser beam is traced around the weld path.

12. The laser welding system of claim 1 1 wherein the trace laser welding subsystems are configured to trace their respective second laser beams around the weld path so that the second laser beams also intersect each other at an angle in the intersection angle range as they are traced around the weld path.