WO2018217922A1

WO2018217922A1 - Simultaneous laser welding with control by profiling

Info

Publication number: WO2018217922A1
Application number: PCT/US2018/034179
Authority: WO
Inventors: Eugene D. POLLASTRO; Scott Caldwell; Adam MACIASZEK; Alex Greenberg
Original assignee: Branson Ultrasonics Corporation
Priority date: 2017-05-26
Filing date: 2018-05-23
Publication date: 2018-11-29

Abstract

Laser channels of a simultaneous laser welding system are controlled using profiling where there is a profile associated with each laser channel for each active weld step of the laser channel and the laser channels are controlled using the respective profiles for each active weld step of each laser channel. In an aspect, the actuator of the simultaneous laser welding system is controlled using one or more of laser light intensity amplitude profiling, force profiling, distance profiling and laser energy profiling. In an aspect, one or more conditions are used to determine when to transition from a step of a cycle of the simultaneous laser welding system. The conditions can be any of time, accumulation of laser energy, actuator position, and actuator force.

Description

SIMULTANEOUS LASER WELDING WITH CONTROL BY PROFILING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/51 1 ,460 filed on May 26, 2017. The entire disclosure of the above application is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to simultaneous laser welding.

BACKGROUND

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

[0004] Laser welding is commonly used to weld plastic parts together. One type of laser welding is through transmissive laser welding such as through transmissive infrared laser welding, commonly referred to as TTIr. During 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. Laser radiation of a suitable wavelength is passed 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.

[0005] One type of TTIr available from Branson Ultrasonics Corporation is simultaneous through transmissive infrared welding referred to herein as STTIr. In STTIr, the full weld path or area (referred to herein as the weld path) is simultaneously exposed to laser radiation, such as through a coordinated alignment of a plurality of laser light sources, such as laser diodes. 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. [0006] In STTIr, the laser radiation is typically transmitted from one or more laser sources to the parts being welded through one or more optical waveguides which conform to the contours of the parts' surfaces being joined along the weld path. Fig. 1 shows an example of a STTIr laser welding system 100. STTIr 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. STTIr laser welding system 100 also includes an actuator 1 10, one or more laser banks 112, 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.

[0007] As best shown in Fig. 2, each laser bank 112 includes one or more channels 122 with each channel 122 having a source 124 of laser radiation, which may illustratively be a laser diode. Each channel 122 is coupled by a fiber bundle 126 to an optical waveguide 128 of upper tool/waveguide assembly 1 14. Waveguide 128 is fixtured in an upper tool 130 of upper tool/waveguide 114. 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. 2 for clarity of Fig. 2, it should be understood that there are sufficient laser banks 1 12 with associated channels 122, fiber bundles 126 and legs 132 terminating in ferrules 134 so that there are 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 around 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 light by these several fibers of the associated fiber bundle 126 from the source 124 of laser radiation of the laser channel 122 to which the leg is coupled via the associated fiber bundle 126.

[0008] In simultaneous laser plastic welding, the weld cycle typically has a series of distinct steps. These steps can include, but are not limited to, any combination of two or more of: a clamp step with no preheat, a preheat step, a weld heat build-up step, a melt step, a hold step, and a post heat step. Typically, in the prior art, during those steps where laser light is being applied to the parts, the laser channels provide laser light at a constant intensity regardless of the step and during those steps where the parts are clamped together, they are clamped together with a constant force regardless of the step. SUMMARY

[0009] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0010] A simultaneous laser welding system for welding plastic parts has one or more laser channels. Each laser channel is controlled using profiling where there is a profile associated with each laser channel for each active weld step of the laser channel and each laser channel is controlled using the respective profile for each active weld step of that laser channel. In an aspect, the actuator of the simultaneous laser welding system is controlled using one or more of laser light intensity amplitude profiling, force profiling, distance profiling and laser energy profiling. In an aspect, one or more conditions are used to determine when to transition from a step of a cycle of the simultaneous laser welding system. The conditions can be any of time, accumulation of laser energy, actuator position, and actuator force.

[0011] In an aspect, a simultaneous laser welding system for laser welding plastic parts has at least one laser bank having a plurality of laser channels. Each laser channel has a laser source that provides laser light. Each laser channel is coupled to an optical waveguide by an associated fiber bundle. The optical waveguide is configured to direct laser light from the laser channels to different areas of the plastic parts. Each laser channel has an active weld cycle during which the laser channel provides laser light. The active weld cycle includes a plurality of active weld steps during which light from that laser channel is provided through the fiber bundle

associated with that laser channel and the waveguide to the plastic parts. A controller is configured to control each laser channel by controlling an amplitude of an intensity of the laser light during each active weld step of the weld cycle of that laser channel in accordance with a predetermined laser light intensity amplitude profile associated with that laser channel for that active weld step that is stored in memory of the controller.

[0012] In an aspect, each laser light intensity amplitude profile is defined as absolute or relative and each relative laser light intensity amplitude profile is assigned to a global intensity group having a global intensity profile, the controller configured to modify each laser light intensity amplitude profile assigned to a particular global intensity group by the global intensity profile of that global intensity group when controlling the laser channel.

[0013] In an aspect, the simultaneous laser welding system includes an actuator coupled to a tool in which the optical waveguide is received that moves the tool against the parts. In an aspect, the controller is configured to control the actuator by controlling a force at which the actuator forces the tool against the parts during each clamp step of a clamp cycle in accordance with a predetermined force profile associated with each clamp step that is stored in memory of the controller. In an aspect, the controller is configured to control the actuator by controlling a distance that the actuator moves during each distance step of a distance cycle in accordance with a predetermined distance profile associated with each distance step that stored in memory of the controller.

[0014] In an aspect, the controller is configured to control the simultaneous laser welding system by transitioning from a current step of an applicable cycle to a next step of the applicable cycle when a condition associated with the current step is met. In an aspect, the condition is a time. In an aspect, the condition is one of a time, a distance that an actuator of the simultaneous laser welding system has moved during the current step, and an amount of laser energy directed to the plastic parts during the current step.

[0015] In an aspect, the controller is configured to determine to transition from a current active weld step of the active weld cycle of each laser channel to a next active weld step of the weld cycle of that laser channel when an amount of laser energy that has been delivered by that laser channel reaches a threshold and upon determining to transition to the next active weld step controlling that laser channel with the controller to transition to the next active weld step.

[0016] 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

[0017] 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. [0018] Fig. 1 is a diagrammatic view of a prior art simultaneous laser welding system;

[0019] Fig. 2 is a diagrammatic view of a laser bank of the simultaneous laser welding system of Fig. 1 ;

[0020] Fig. 3 is a graph of laser light intensity amplitude profiles for control of a laser channel during active weld steps of the laser channel and that are associated with the laser channel in accordance with an aspect of the present disclosure;

[0021] Fig. 4 is another graph of laser light intensity amplitude profiles for control of a laser channel during active weld steps of the laser channel and that are associated with the laser channel in accordance with an aspect of the present disclosure;

[0022] Fig. 5 is a flow chart of control logic for a control routine for control of a laser channel using the laser light intensity amplitude profiles of Fig. 3 or Fig. 4 in accordance with an aspect of the present disclosure;

[0023] Fig. 6 is another graph of laser light intensity amplitude profiles for control of a laser channel during active weld steps of the laser channel and that are associated with the laser channel in accordance with an aspect of the present disclosure showing some of the profiles assigned to global intensity groups;

[0024] Fig. 7 is a flow chart of control logic for a control routine for control of a laser channel using the laser light intensity amplitude profiles of Fig. 6;

[0025] Fig. 8 is a graph of force level profiles for control of an actuator of a simultaneous laser welding system in accordance with an aspect of the present disclosure;

[0026] Fig. 9 is a flow chart of control logic for a control routine for control of an actuator of a simultaneous laser welding system using the force level profiles of Fig. 9 in accordance with an aspect of the present disclosure; and

[0027] Fig. 10 is a graph of distance profiles for control of an actuator of a simultaneous laser welding system in accordance with an aspect of the present disclosure;

[0028] Fig. 1 1 is a graph of a laser energy profile for control of a laser channel during active weld steps of the laser channel and that are associated with the laser channel in accordance with an aspect of the present disclosure; and

[0029] Fig. 12 is a flow chart of control logic for a control routine for control of a laser channel using the laser energy profile of Fig. 1 1. [0030] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0031] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] In simultaneous laser welding, it may be desirable to control each laser channel to provide laser light at different amplitudes of laser intensities during different active weld steps of an active weld cycle of the laser channel (that is, in accordance with a laser light intensity amplitude profile for that active weld step that is associated with that laser channel), which may include different constant amplitudes of laser light intensities during different active weld steps of the laser channel, varying the amplitude of intensity of laser light differently during different active weld steps, or a combination thereof. It may also be desirable to define the laser light intensity amplitude profiles as absolute or relative and assign each relative laser light intensity amplitude profile to a particular global intensity group and modify each laser light intensity profile assigned to a particular global intensity group by a global intensity profile of that global intensity group. It may also be desirable to control the actuator of the simultaneous laser welding system to clamp the parts together at different force intensities during clamp steps of a clamp cycle. It may also be desirable to control the distance the actuator of the simultaneous laser welding system moves in accordance with a distance profile or profiles.

[0038] It may also be desirable to control each laser channel so that the transitions from an active weld step to the next active weld step are determined by the amount of laser energy that the laser channel has delivered to the parts being welded. In this regard, it may be desirable to control each laser channel to deliver different predetermined amounts of laser energy during different steps of the weld cycle.

[0039] While these control methodologies are described in more detail below with reference to prior art simultaneous laser welding system 100 of Fig. 1 , it should be understood that these control methodologies are not in the prior art. It should also be understood that while these control methodologies are described with reference to STTIr system 100, which may sometimes be referred to herein as simultaneous laser welding system 100, it should be understood that they are not limited in applicability to only simultaneous laser welding that is STTIr welding.

[0040] Fig. 3 shows in graphical form example laser light intensity amplitude profiles of laser light to which controller 104 controls one of laser channels 122 during active weld steps of an active weld cycle of that laser channel 122. As used herein, the active weld cycle is that portion of a weld cycle during which laser light is being provided to the plastic parts being welded by that laser channel 122 and the active weld steps are the steps of the active weld cycle, that is, the steps during which laser light is being provided to the plastic parts being welded by that laser channel 122. Each laser channel 122 illustratively has a laser light intensity amplitude profile for each active weld step with the laser light intensity amplitude profiles stored in memory of controller 104. Controller 104 controls the amplitude of intensity of the laser light output by the laser channel 122 during each active weld step of that laser channel 122 in accordance with the laser light intensity amplitude profile for that active weld step. The laser light intensity amplitude profiles are illustratively determined heuristically for the particular parts being welded.

[0041] As used herein, the reference LLIP_X will be used to refer to individual laser light intensity energy amplitude profiles and the reference S_x will be used to refer to individual active weld steps. [0042] In the example of Fig. 3, the active weld steps begin at time to and end at time f₇. There are thus seven active weld steps Si, S₂, S3, S₄, S5, Se, S7 in the active weld cycle during which laser light is provided to the plastic parts being welded by the particular laser channel 122 with each active weld step of these active weld steps beginning when a begin time for that active weld step is reached and ending when an end time for that active weld step is reached. That is, weld steps Si, S₂, S3, S4, S5, Se, S₇ begin respectively at times to, , t₂, t_3: t₄, t_5: t₆. and end respectively at , t₂, t₃, t₄, t₅, f_6, t_7. Each active weld step S_1: S₂, S3, S₄, S₅, S₆, S₇ has one of laser light intensity amplitude profiles LLIP₁ - LLIP₇, respectively, associated with it. It should be understood that the weld cycle has steps both before and after the active weld cycle, that is, before and after active weld steps S₁ - S₇, such as when actuator 1 10 is moving upper tool/waveguide assembly 1 14 toward the parts to be welded before the active weld cycle of that laser channel 122 begins and away from the welded parts after the active weld cycle of that laser channel 122. It should also be understood that a condition other than time can be used to determine when the weld cycle transitions to the next weld step, as discussed in more detail below. In the example of Fig. 3, the amplitude of the intensity of the laser light during each active weld step Si - S7 is constant. In the example of Fig. 3, the amplitudes in the laser light intensity amplitude profiles of adjacent active weld steps are different, but it should be understood that they could be the same or different. It should be understood that in the example of Fig. 3, the vertical lines demarking the different active weld steps are included for clarity and do not mean that the amplitude of intensity of laser light at the beginning and end of each active weld step returns to zero before changing to the next value in the applicable laser light intensity amplitude profile.

[0043] Fig. 4 shows in graphical form another example of laser light intensity amplitude profiles of laser light to which controller 104 controls one of laser channels 122 during the active weld steps of the active weld cycle of the laser channel 122. In the example of Fig. 4, there are four active weld steps Si, S₂, S3, S₄ having associated laser light intensity amplitude profiles LLIP - LLIP₄, respectively. In the example of Fig. 4, the amplitude of intensity of laser light is varied during active weld steps S1 , S3 and S4 in accordance with LLIP-i , LLIP₃ and LLIP₄, respectively. In active weld step S<_\ , the amplitude of intensity of laser light is increased in a linear ramp up in accordance with LLIP-i . In active weld step S₂, the amplitude of intensity of laser light is constant in accordance with LLIP₂. In active weld step S³, the amplitude of intensity of laser light is varied according to a varying curve in accordance with LLIP₃. In active weld step S₄, the amplitude of intensity of laser light is decreased in a linear ramp down in

accordance with LLIP₄.

[0044] It should be understood that the laser light intensity amplitude profiles for the laser channels 122 can be different from each other or the laser light intensity amplitude profiles for a plurality of the laser channels 122 can be the same. It should also be understood that the active weld steps for each laser channel 122 need not be the same and can be different. For example, one of laser channels 122 in one of laser banks 1 12 can have the laser light intensity amplitude profiles shown in Fig. 3 and another of laser channels 122 in the same laser bank 1 12 can have the laser light intensity amplitude profiles shown in Fig. 4.

[0045] Fig. 5 is a flow chart of control logic for an example control routine implemented in controller 104 for controlling each laser channel 122 using amplitude profiling to control amplitude of intensity of laser light provided by that laser channel 122 during the active weld steps of that laser channel 122. It should be understood that controller 104 controls the laser channels 122 in parallel using the control routine of Fig. 5 for each laser channel 122. The control routine starts at 500 and proceeds to 502 where it checks whether the first active weld step has been reached for the laser channel 122. If not, the control routine branches back to 502. If so, the control routine proceeds to 504 where it reads the laser light intensity amplitude profile associated with the laser channel 122 for the current active weld step of that laser channel 122 and proceeds to 506. At 506, the controller 104 controls that laser channel 122 by controlling it to provide laser light at an intensity in accordance with the laser light intensity amplitude profile associated with that laser channel 122 for the current active weld step of that laser channel 122. The control routine then proceeds to 508 where it determines whether to transition to the next weld step. If not, the control routine branches back to 508. If so, the control routine proceeds to 510 where it determines whether the active weld cycle of that that laser channel 122 is over. If so, the control routine proceeds to 512 where it ends. If not, the control routine branches back to 504.

[0046] Fig. 6 shows in graphical form an example of active weld cycles for a plurality of laser channels 122 identified in Fig. 6 as laser channels 1211 - 122_n. Active weld cycle of laser channel 122i includes seven active weld steps Si - S₇, active weld cycle of laser channel 122₂ includes three active weld steps Si - S₃, and active weld cycle of laser channel 122_n includes four active weld steps Si - S₄. Each active weld step S_x has an associated laser light intensity amplitude profile identified by LLIP_X where x is the subscript that identifies the particular weld step. That is, active weld steps Si - S₇ of laser channel 122i have respective laser light intensity amplitude profiles LLIP1 - LLIP₇, active weld steps S2 - S3 of laser channel 122₂ have respective laser light intensity amplitude profiles LLIP! - LLIP₃, and active weld steps Si - S₄ of laser channel 122_n have respective light intensity amplitude profiles LLIP1 - LLIP₄. Each amplitude profile LLIP_X is defined in controller 104 as absolute (identified by A in Fig. 6) or relative. Each amplitude profile P_x defined as relative is assigned in controller 104 to a global intensity group, such as global intensity groups identified by Gi and G₂ in the example of Fig. 6. Illustratively, a user enters into controller 104 the definition of each amplitude profile P_x as absolute or relative and the assignment of each relative amplitude profile P_x to a particular global intensity group. Each global intensity group has a global intensity profile, which can be a constant value or can have varying values such as defined by a linear ramp or a curve.

[0047] Controller 104 controls each of laser channels 122i - 122_n during each active weld step of that laser channel 122_x to provide laser light having a laser light intensity amplitude in accordance with the laser light intensity amplitude profile LLIP_x for the particular active weld step S_x of that laser channel 122_x. For the laser light amplitude profiles defined as absolute, the control is as described above. For the laser light intensity amplitude profiles defined as relative, controller 104 modifies the laser light intensity amplitude profiles by the global intensity value of the global intensity group to which the laser light intensity amplitude profile is assigned. For example, if the global intensity profile is a constant value, controller 104 determ ines the amplitude of the laser light intensity to control the respective laser channel to provide during the respective active weld step by multiplying the laser light intensity amplitude profile LLIP_X by the constant value. In the example of Fig. 6, the global intensity value of global intensity group Gi is 150% and the global intensity value of global intensity group G₂ is 50%. The dashed lines in Fig. 6 show the laser light intensity amplitude profiles defined as relative as modified by the global intensity value of the global intensity group to which the laser light intensity amplitude profiles are assigned.

[0048] Fig. 7 is a flow chart of control logic for an example control routine that is a variation of the control routine of Fig. 5 and which includes modifying the laser light intensity amplitude profiles assigned to global intensity groups by the global intensity profile of the global intensity group to which the amplitude profile is assigned. The control routine of Fig. 7 is the same as the control routine of Fig. 5 with the exception of additional control blocks 700, 702. In the control routine of Fig. 7, after the laser light intensity amplitude profile LLIP_X associated with a particular laser channel 122 for the current active weld step of that laser channel 122 is retrieved, the control routine proceeds to 700 where it checks whether the retrieved laser light intensity amplitude profile LLIP_X is assigned to a global intensity group. If the retrieved laser light intensity amplitude profile LLIP_X is not assigned to a global intensity group, the control routine proceeds to 506. If the retrieved laser light intensity amplitude profile LLIP_X is assigned to a global intensity group, the control the control routine proceeds to 702 where it controls that laser channel 122 by controlling it to provide laser light at an intensity in accordance with the retrieved laser light intensity amplitude profile LLIP_X associated with that laser channel 122 for the current active weld step S_x of that laser channel 122 modified by the global intensity profile of the global intensity group to which that retrieved laser light intensity amplitude profile LLIP_X is assigned.

[0049] In an aspect, controller 104 also controls actuator 110 to control a level of force at which upper tool/waveguide assembly 1 14 is urged against the parts being welded during clamp steps of a clamp cycle of the weld cycle during which upper tool/waveguide is urged against the parts being welded. It should be understood that these clamp steps may differ from the active weld steps described above. For example, upper tool/waveguide assembly 1 14 may be urged against the parts being welded with a force prior to active welding beginning. The steps during which upper tool/waveguide assembly 1 14 is urged against the parts being welded with a force will be referred to herein as clamp steps in that upper tool/waveguide assembly 1 14 is being clamped against the parts being welded during these clamp steps. Individual clamp steps may be referred to herein as C_x.

[0050] Fig. 8 shows in graphical form an example of clamp steps of a clamp cycle for laser welding system 100. The clamp cycle includes three clamp steps Ci - C3 with these clamp steps having associated force level profiles FPi - FP3,

respectively. During each clamp step C_x, controller 104 controls actuator 1 10 to urge upper tool/waveguide assembly 1 14 against the parts being weld at a force level in accordance with the force level profile FP_X for that clamp step C_x.

[0051] Fig. 9 is a flow chart of control logic for an example control routine implemented in controller 104 for controlling actuator 1 10 using force profiling to control actuator 110 to control the level of force at which upper tool/waveguide assembly 1 14 is urged against the parts being welded during the clamp steps of the clamp cycle. It should be understood that controller 104 controls actuator 1 10 in parallel with the above described control of laser channels 122. The control routine starts at 900 and proceeds to 902 where it checks whether the first clamp step has been reached for laser welding system 100. If not, the control routine branches back to 702. If so, the control routine proceeds to 704 where it reads the force level profile for the current clamp step 706. At 706, the controller 104 controls actuator 1 10 by controlling it to urge upper

tool/waveguide assembly 1 14 against the parts being welded at a force level in accordance with the force level profile for the current clamp step. The control routine then proceeds to 908 where it determ ines whether to transition to the next clamp step. If not, the control routine branches back to 908. If so, the control routine proceeds to 910 where it determines whether the clamp cycle is over. If so, the control routine proceeds to 912 where it ends. If not, the control routine branches back to 904.

[0052] Fig. 10 shows in graphical form an example of distance steps of a distance cycle for laser welding system 100. The distance cycle includes five distance steps Di - D5 with these distance steps having associated distance profiles DPi - DP5 , respectively. During each distance step D_x, controller 104 controls actuator 1 10 to move toward or away from the parts being welded in accordance with the distance profile DP_X for that distance step D_x. The control routine implemented in controller 104 for controlling actuator 110 using distance profiling to control actuator 1 10 to control the distances that actuator 1 10 is moving is the same as the control routine of Fig. 9 except that the profile used is the distance profile and not the force profile.

[0053] Fig. 1 1 shows in graphical form an example of a laser energy profile to which controller 104 controls one of laser channels 122 during active weld steps of an active weld cycle of that laser channel 122. In the example of Fig. 1 1 , the active weld cycle of laser channel 122 has three active weld steps Si - S₃. Controller 104 transitions laser channel 122 to the next weld step when the laser energy that has been delivered by laser channel 122 to the parts being welded reaches a threshold amount for each transition. That is, controller 104 transitions laser channel 122 from Si to S₂ when the amount of laser energy that has been delivered by laser channel 122 reaches LE-i, transitions laser channel 122 from S2 to S3 when the amount of laser energy that has been delivered by laser channel 122 reaches LE₂, and ends active welding when the amount of laser energy that has been delivered by laser channel 122 reaches LE₃. While Fig. 1 1 shows the amount of laser energy being delivered by laser channel 122 increasing at a constant rate through active weld steps S1 - S3, it should be

understood that the rate at which the amount of laser energy increases during each active weld step can differ. It should also be understood that the threshold amount for each transition could be a total amount of laser energy that the laser channel has delivered during the active weld cycle or the total amount of laser energy that the laser channel has delivered during that particular active weld step.

[0054] Fig. 12 is a flow chart showing of control logic for an example control routine implemented in controller 104 for controlling a laser channel 122 during the active weld steps of that laser channel 122 using a laser energy profile, such as the laser energy profile of Fig. 1 1. The control routine starts at 1200 and proceeds to 1202 where it checks whether the first active weld step has been reached for the laser channel 122. If not, the control routine loops back to 1202. If so, the control routine proceeds to 1204 where it reads the laser energy profile for that laser channel 122 and controls laser channel 122 for the first active weld step Si. The control routine then proceeds to 1206 where it checks whether the next laser energy transition has been reached. If not, the control routine branches back to 1206. If so, the control routine proceeds to 1208 where it transitions laser channel 122 to the next active weld step and controls laser channel 122 for the next active weld step unless it determines at 1210 that the active weld cycle of that laser channel 122. If at 1210 the control routine determines that the active weld cycle of that laser channel 122 is not over, the control routine branches back to 1208. If at 1210 the control routine determines that the active weld cycle of that laser channel 122, the control routine proceeds to 1212 where it ends.

[0055] Simultaneous laser welding system 100 can include various cycles, such as the aforementioned active weld cycles for each laser channel and the

aforementioned clamp and distance cycles for the actuator with each cycle having a plurality of steps. Controller 104 uses one or more conditions to determine when to transition from an individual step. For example, with reference to Figs. 3, 4, 6, 8 and 10, time is the condition that controller 104 uses to determine when to transition from the current active weld step (Figs. 3, 4 and 6), current clamp step (Fig. 8), or current distance step (Fig. 10). Other conditions can also be used such as when an amount of laser energy directed to the transmissive part reaches a certain level, when a position of actuator 1 10 reaches a certain position, when a force that the actuator 1 10 is exerting reaches a certain level, such as but not limited to a level of force that occurs when the parts being welded begin to melt. In this regard, more than one condition can be used to determine when to transition from the current step to the next step. The condition or conditions used to determine when to transition from any particular step can vary from step to step and need not be the same.

[0056] Controller 104 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), such as control logic shown in the flow charts of Figs. 5, 7 and 9. 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.

[0057] 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 simultaneous laser welding plastic parts using a simultaneous laser welding system having at least one laser bank having a plurality of laser channels, each laser channel having a laser source that provides laser light, each laser channel coupled to an optical waveguide by an associated fiber bundle, the optical waveguide configured to direct laser light from the laser channels to different areas of the plastic parts, each laser channel controlled by a controller of the simultaneous laser welding system, each laser channel having an active weld cycle during which the laser channel provides laser light, the active weld cycle including a plurality of active weld steps, the method comprising:

during each active weld step of an active weld cycle of each laser channel, providing laser light from that laser channel through the fiber bundle associated with that laser channel and the waveguide to the plastic parts; and

controlling that laser channel with the controller by controlling an amplitude of an intensity of the laser light during each active weld step of the weld cycle of that laser channel in accordance with a predetermined laser light intensity amplitude profile associated with that laser channel for that active weld step that is stored in memory of the controller.

2. The method of claim 1 wherein each laser light intensity amplitude profile is defined as absolute or relative and each relative laser light intensity amplitude profile is assigned to a global intensity group having a global intensity profile, the method further including modifying each laser light intensity amplitude profile assigned to a particular global intensity group by the global intensity profile of that global intensity group when controlling the laser channel.

3. The method of claim 1 wherein the simultaneous laser welding system includes an actuator coupled to a tool in which the optical waveguide is received that moves the tool against the parts, the method including controlling the actuator with the controller by controlling a force at which the actuator forces the tool against the parts during each clamp step of a clamp cycle in accordance with a predetermined force profile associated with each clamp step that is stored in memory of the controller.

4. The method of claim 1 wherein the simultaneous laser welding system includes an actuator coupled to a tool in which the optical waveguide is received that moves the tool against the parts, the method including controlling the actuator with the controller by controlling a distance that the actuator moves during each distance step of a distance cycle in accordance with a predetermined distance profile associated with each distance step that stored in memory of the controller.

5. The method of claim 1 including controlling the simultaneous laser welding system with the controller by transitioning from a current step of an applicable cycle to a next step of the applicable cycle when a condition associated with the current step is met.

6. The method of claim 5 wherein the condition is a time.

7. The method of claim 5 wherein the condition is one of a time, a distance that an actuator of the simultaneous laser welding system has moved during the current step, and an amount of laser energy directed to the plastic parts during the current step.

8. A method of simultaneous laser welding plastic parts using a simultaneous laser welding system having at least one laser bank having a plurality of laser channels, each laser channel having a laser source that provides laser light, each laser channel coupled to an optical waveguide by an associated fiber bundle, the optical waveguide configured to direct laser light from the laser channels to different areas of the plastic parts, each laser channel controlled by a controller of the simultaneous laser welding system, each laser channel having an active weld cycle during which the laser channel provides laser light, the active weld cycle including a plurality of active weld steps, the method comprising:

determining with the controller to transition from a current active weld step to a next active weld step when an amount of laser energy that has been delivered by the laser channel reaches a threshold and upon determining to transition to the next active weld step controlling that laser channel with the controller to transition to the next active weld step.

9. A simultaneous laser welding system for laser welding plastic parts; comprising:

at least one laser bank having a plurality of laser channels, each laser channel having a laser source that provides laser light, each laser channel coupled to an optical waveguide by an associated fiber bundle, the optical waveguide configured to direct laser light transmitted from the laser sources of the laser channels through the fiber bundles to the optical waveguide to different areas of the plastic parts;

each laser channel having an active weld cycle during which the laser channel provides laser light, the active weld cycle including a plurality of active weld steps during which light from that laser channel is provided through the fiber bundle associated with that laser channel and the waveguide to the plastic parts; and

a controller configured to control each laser channel by controlling an amplitude of an intensity of the laser light during each active weld step of the weld cycle of that laser channel in accordance with a predetermined laser light intensity amplitude profile associated with that laser channel for that active weld step that is stored in memory of the controller.

10. The simultaneous laser welding system of claim 9 wherein each laser light intensity amplitude profile is defined as absolute or relative and each relative laser light intensity amplitude profile is assigned to a global intensity group having a global intensity profile, the controller configured to modify each laser light intensity amplitude profile assigned to a particular global intensity group by the global intensity profile of that global intensity group when controlling the laser channel.

1 1. The simultaneous laser welding system of claim 9 further including an actuator coupled to a tool in which the optical waveguide is received that moves the tool against the parts, the controller configured to control the actuator by controlling a force at which the actuator forces the tool against the parts during each clamp step of a clamp cycle in accordance with a predetermined force profile associated with each clamp step that is stored in memory of the controller.

12. The simultaneous laser welding system of claim 9 further including an actuator coupled to a tool in which the optical waveguide is received that moves the tool against the parts, the controller configured to control the actuator by controlling a distance that the actuator moves during each distance step of a distance cycle in accordance with a predetermined distance profile associated with each distance step that stored in memory of the controller.

13. The simultaneous laser welding system of claim 9 wherein the controller is configured to control the simultaneous laser welding system by transitioning from a current step of an applicable cycle to a next step of the applicable cycle when a condition associated with the current step is met.

14. The simultaneous laser welding system of claim 13 wherein the condition is a time.

15. The simultaneous laser welding system of claim 13 wherein the condition is one of a time, a distance that an actuator of the simultaneous laser welding system has moved during the current step, and an amount of laser energy directed to the plastic parts during the current step.

16. A simultaneous laser welding system for laser welding plastic parts; comprising:

at least one laser bank having a plurality of laser channels, each laser channel having a laser source that provides laser light, each laser channel coupled to an optical waveguide by an associated fiber bundle, the optical waveguide is configured to direct laser light from the laser channels to a different areas of the plastic parts;

each laser channel having an active weld cycle during which the laser channel provides laser light, the active weld cycle including a plurality of active weld steps during which laser light from that laser channel is provided through the fiber bundle associated with that laser channel and the waveguide to the plastic parts; and

a controller configured to control each laser channel, the controller configured to determine to transition from a current active weld step of the active weld cycle of each laser channel to a next active weld step of the weld cycle of that laser channel when an amount of laser energy that has been delivered by that laser channel reaches a threshold and upon determining to transition to the next active weld step controlling that laser channel with the controller to transition to the next active weld step.