Method for locating a welding energy director

Abstract

Method for locating a welding energy director (200) for welding together a plurality of workpieces (101 1 , 101 2 ) in a region of the energy director (200), comprising: Positioning a workpiece assembly in preparation for making one or more approaches to locate the energy director (200), the workpiece assembly including a proximal workpiece (101 1 ) of the several workpieces, a distal workpiece (101 2 ) containing a plurality of workpieces and the welding energy director (200) located therebetween; and Executing a localization subroutine by a computing device as a controller, said localization subroutine comprising: Moving a welding sonotrode (106) from a first lateral position above the proximal workpiece (101 1) which is closest to the welding sonotrode (106), in a lowering movement towards the proximal workpiece (101 1 ); Determine in a location determination whether a through the proximal workpiece (101 1 ) applied to the welding sonotrode (106) and received by the welding sonotrode (106) indicates that the welding sonotrode (106) has been lowered to a local endpoint, wherein the location determination further comprises the controller determining a displacement value reached by the welding sonotrode (106) when the resistance force exerted by the proximal workpiece (101 1 ) the resistance force exerted on the welding sonotrode (106) has reached a threshold value; and Lateral repositioning of the welding sonotrode (106) for a further, laterally offset approach movement towards the proximal workpiece (101 1) and repeating the subroutine method steps of lowering movement and location determination until, upon reaching the threshold value of the resistance force, the displacement value achieved by the welding sonotrode (106) is smaller than the threshold displacement, whereupon it is determined that the energy director (200) is located directly below an area in which the welding sonotrode (106) was positioned.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to an improved technique for welding multiple workpieces together and, more particularly, to a method for locating a weld energy director. BACKGROUND

[0002] Polymer composites are increasingly being used in automotive manufacturing due to their advantageous properties, such as being lightweight, highly conformable or moldable, strong, and durable. Some composites are also colorable and can be surface-treated to achieve virtually any desired texture.

[0003] Increased automotive applications include instrument panels and door panel elements, lamps, air ducts, steering wheels, upholstery, truck beds or other vehicle storage compartments, upholstery, exterior parts, and even engine components. For engine components and other under-the-hood (UTH) applications, for example, polymers are being designed and continually developed that can withstand hot and / or chemically aggressive environments. For exterior parts such as bumpers, polymers are being developed that are paintable on the production line and exhibit very high heat and chemical resistance over extended periods. In addition, many other potential uses in automotive applications are constantly being considered.

[0004] With the increasing use of polymers and other low-mass materials, compression molding and post-molding joining techniques—such as ultrasonic welding—are also becoming more common.

[0005] Because some materials in increasing use, including polymer composites, have relatively low melting points, efforts to melt parts at an interface joining the parts quickly and with minimal melting of other portions of the workpieces pose a challenge.

[0006] Occasionally, energy directors are used to accelerate and control welding, as is known, for example, from the documents DE 43 21 874 A1, US 4 631 685 A or US 2009 / 0 188 966 A1.

[0007] Several challenges arise. One is that it's difficult for the welder to try to focus the welding on the energy director to determine exactly where it is, since the energy directors are typically not visible at the time of welding. Currently, the directors cannot be placed precisely, or they require a lot of extra work and time—that is, manually by eye and hand.

[0008] The increased time and energy requirements are prohibitive, especially when multiplied by repeated iterative processing in a manufacturing environment—e.g., an automobile assembly plant.

[0009] Although EP 0 076 135 A2 describes the detection of objects using tactile pressure sensors, since the objects are randomly oriented, the position of one object cannot be used to determine the position of another. The invention is therefore based on the object of providing a solution to the previously described problem of detecting energy direction sensors. SUMMARY

[0010] This object is achieved by a method having the features of claim 1.

[0011] The present technology relates to systems and methods for enhanced ultrasonic welding using an algorithm for automatic localization of energy directing devices during welding.

[0012] The algorithm outlines a subprocess by which locations of energy steering devices or energy directors are identified. The locations are determined based on a displacement undergone by the sonotrode, which is controlled to move in a predetermined manner toward the workpieces between which the device sits, to a point where the sonotrode counteracts a threshold restoring force from the proximal workpiece.

[0013] Other aspects of the present invention will be in part obvious and in part shown hereinafter. DESCRIPTION OF THE DRAWINGS Fig. Figure 1 illustrates a two-sided ultrasound system. Fig. 2 illustrates an exemplary multi-altitude energy director in accordance with an embodiment of the present technology. Fig. 3 illustrates a leg or projection of the multi-altitude energy director of Fig. 2. Fig. Figure 4 illustrates a method for locating an energy director such as the multi-altitude energy director of Fig. 2, which is positioned between workpieces to be welded together, and carrying out the welding to join the pieces. Fig. Figure 5 illustrates a side view of the multi-altitude energy director of Fig. 2, which is positioned between the workpieces. Fig. Figure 6 illustrates welding tool positions caused when locating the workpiece in accordance with example scenarios. Fig. Figure 7 shows a graph comparing welding tool displacement in an application direction (e.g., vertical) and in an orthogonal tool position (e.g., a lateral location above the tool). Fig. 8 illustrates the multi-altitude energy director from Fig. 2 in an intermediate phase of welding, before the second plane of the directional sensor touches the second workpiece. Fig. 9 illustrates the multi-altitude energy director from Fig. 2 in a subsequent intermediate phase of welding in which the second plane of the directional sensor first touches the second workpiece. Fig. Figure 10 illustrates an exemplary weld made using the energy director of Fig. 2 has been formed. Fig. 11 illustrates an exemplary control unit for use in carrying out the operations of the method of Fig. 4. DETAILED DESCRIPTION

[0014] As required, detailed embodiments of the present disclosure are disclosed herein. The disclosed embodiments are merely examples that may be embodied in various and alternative forms and combinations thereof. As used herein, for example, exemplary, and similar terms refer broadly to embodiments that serve as an illustration, example, model, or pattern.

[0015] The figures are not necessarily to scale, and some features may be exaggerated or reduced, such as to show details of particular components. To avoid obscuring the present disclosure, in some cases, well-known components, systems, materials, or methods have not been described in detail. Thus, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the following recited technology focuses (e.g., claims) and as a representative basis for teaching those skilled in the art to variously utilize the present disclosure.

[0016] Although the description includes a general context of computer-executable instructions, the present disclosure may also be implemented together with other program modules and / or as a combination of hardware and software. The term application or variants thereof is used broadly herein to include routines, program modules, programs, components, data structures, algorithms, and the like. Applications may be implemented in various system configurations, including single-processor or multi-processor systems, microprocessor-based electronics, combinations thereof, and the like. I. General Overview of Revelation

[0017] The present disclosure describes an ultrasonic welding technique for joining workpieces such as polymer composites.

[0018] One aspect of the disclosure relates to systems and methods for enhanced ultrasonic welding. The system includes an algorithm (e.g., computer-readable code) configured to control device elements to locate the multi-height energy directing device for welding at the identified location. The location is determined based on a displacement traversed by a weld head, a weld tip, or a horn, such as an ultrasonic servo horn, controlled to move in a predetermined manner toward the workpieces between which the device is seated, to a point at which the horn counteracts a threshold restoring force from the proximal workpiece.

[0019] More precisely, the welding tool is lowered onto a proximal workpiece of the two workpieces to be joined and between which the energy director is located.

[0020] As the horn is controlled to descend onto the workpiece, a controller receives feedback indicating a force or resistance that opposes the downward movement. According to the algorithm, e.g., computer-executable instructions, the controller determines the distance traveled by the horn before the horn counteracts a predetermined threshold force.

[0021] If the distance traveled indicates that a horn is not directly above the location of the workpiece immediately below which the energy directory is located, the controller will command the horn, based on the last measured values, to move to another location, preferably closer to the center of the director, and repeat the descent and measurement at the new position.

[0022] If the distance traveled indicates that the sonotrode is directly above a location on the workpiece where the energy director is located, welding is performed. For many reasons, welding is advantageously performed with the multi-height director configuration of the present technology.

[0023] In the following, the system components, the algorithm and the workflows are described using Fig. 1-9 further described. II. Process, system tooling and workpieces - Fig. 1-11

[0024] The present technology will now be described with reference to exemplary systems, exemplary tooling, and exemplary workpieces. Reference is made to the figures to facilitate understanding of the technology.

[0025] Reference to directions such as upper, lower, upward, downward, and lateral is provided here to facilitate the description of the present technology. For example, a description in which a servo horn is described as descending toward a proximal workpiece is not limited to the horn moving vertically downward in the Earth or ambient frame. For example, the horn may move from left to right in the ambient frame. II.A. General welding system - Fig. 1

[0026] Now moving on to the figures and especially to the first figure, Fig. 1 shows an exemplary welding system, generally designated by reference numeral 100. The system 100 is used to weld two workpieces 101 1 , 101 2 to weld together.

[0027] The system 100 includes a support structure or substructure 102. The system also includes a welding arm 104 terminating in a welding energy application tip or horn 106. The horn may include, for example, an ultrasonic servo horn configured to apply energy in the form of high-frequency vibrations to the workpieces to weld them together.

[0028] The welding arm 104 extends from a second or application-side structure or mass 108.

[0029] During operation, an application direction force 110 can be applied by and / or at the mass 108. The force 110 pushes the arm 104 and the sonotrode 106 toward the workpieces 101 being welded together. A counterforce 112 pushes the support structure 102 toward the workpieces. With the mass and the force in the application direction, which push from a first application direction toward the workpieces 101, and with the counterforce 112, which pushes from an opposite direction toward the pieces 101, the workpieces 101 are held under a desired pressure during welding. II.B. Multi-height energy steering device - Fig. 2 and 3

[0030] Fig. 2 shows an energy steering device or energy director 200.

[0031] The energy director 200 may include any material described herein, including in conjunction with the workpieces.

[0032] In one embodiment, the energy director 200 is generally annular—e.g., having a generally annular or ring-like plan view profile (e.g., profile from above). In the figure, an upper portion of the annular configuration is designated by reference numeral 202.

[0033] Importantly, it has been established that an annular weld can be as strong as continuous welds (i.e., welds without a central void)—in one present result, this is particularly true when a ratio of an inner diameter to an outer diameter is less than about 0.6. More specifically, under an applied tensile load, a predominant amount of the holding force generated by a continuous or continuous weld is supplied by an outer annular portion of the weld, while a central portion of the weld contributes comparatively little holding force. Thus, a weld lacking the central portion can be formed with less energy than a continuous weld (one lacking a central void), and perhaps in less time, without sacrificing joint strength.

[0034] Although the energy director 200, whether annular or otherwise shaped, may have different widths 208, in one embodiment, each director has a width 208 (e.g., a diameter or maximum width) between about 3 mm and about 20 mm. In one embodiment, the width 208 may be between about 1 mm and about 20 mm.

[0035] The upper portion 202 defines a central hole or cavity 204. Although the cavity 204, whether circular, oval, rectangular, or other, may have other internal widths 210, in one embodiment, each director 200 has one or more internal widths 210 between about 1.5 mm and about 12 mm. In one embodiment, the internal width 208 may be between about 0.6 mm and about 12 mm.

[0036] Although the illustrated direction finder 200 has a generally annular plan view profile shape, the direction finder may have other general plan view profile shapes. Other example shapes include oval, square, or other rectangular shapes with a central cavity.

[0037] The energy director 200 includes a plurality of energy director (ED) elements 206. The elements may be referred to by other terms such as an elevation control ED element, an elevation control ED protrusion, or an elevation control ED web, or as a level control element, a level control protrusion, or a level control web.

[0038] As in Fig. 2, the ED elements 206 extend from or protrude from the upper portion 202 of the director 200 (e.g., protrude downward). In one embodiment, the ED 200 is formed during the compression molding of one of the workpieces (e.g., the proximal workpiece 101 1 ) and is thus a coherent part of this workpiece.

[0039] Although the ED element 206 may have other shapes, in the illustrated embodiment, each directional indicator has a generally triangular side profile. Other exemplary shapes include square, otherwise rectangular, or rounded—e.g., semicircular or oval.

[0040] In the illustrated embodiment, each ED element 200 includes a top or first side or base that is connected to the upper portion 202 of the element 206. In the embodiment in which the ED 200 is used during compression molding of one of the workpieces (e.g., the proximal workpiece 101 1 ) and thus is a continuous part of this workpiece, the upper portion 202 of the element 206 contains the workpiece 101 1 . The sides extend from the base to a point opposite the upper portion 202.

[0041] It is important that the ED elements 206 do not all have the same properties. In one embodiment, at least one property that differs between at least some of the ED elements 206 is a height 212 of the elements. Advantages of this feature are discussed below in connection with the welding process of method 400 of Fig. 4 further described.

[0042] In general, the advantages relate to a favorable channeling of the welding energy - e.g. the ultrasonic vibrations - initially through primary ED elements, while in an early phase of welding less or not all of it passes through the secondary ED elements and through the secondary elements, while in a subsequent phase of welding less or not all of it passes through the primary ED elements.

[0043] Fig. 3 shows a side view of any of the ED elements 206 of Fig. 2. Together with the Fig. 2 indicated height 212 shows Fig. 3 that the ED elements 206 may be defined by other features such as the width 302.

[0044] Although the ED elements 206 may have different widths 302, in one embodiment, each ED element 206 has a width 302 between about 1.0 mm and about 4.0 mm. In one embodiment, the width 302 may be between about 0.2 mm and about 4.0 mm.

[0045] Continue with the triangular design from Fig. 2 and Fig. 3 shows Fig. 3 a vertical side length 304 as another size property of the ED direction sensor.

[0046] In one embodiment, a ratio of the height 212 to the width 302 (H / W) is between about 0.3 and about 1.0.

[0047] In one embodiment, each primary element 206 1 of the elements 206 has a height between about 0.5 mm and about 6.0 mm and each secondary element 206 2 a height between about 0.4 mm and about 4.0 mm.

[0048] The ED elements 206 may have any suitable thickness and, in connection therewith, any desired three-dimensional shape, and each element may have any desired size—e.g., any desired thickness or thicknesses. The elements 206 may have a general pyramidal shape. For ED elements that have rounded sides, the three-dimensional shape may be prismatic (e.g., that of a rectangular or triangular prism), cylindrical, conical, frustoconical, pyramidal (e.g., that of a triangular pyramid or tetrahedron), semi-spherical (e.g., hemispherical, half-sphere, or hemispherical), etc. The ED elements 206 may have straight and / or curved sides.

[0049] As mentioned, the ED elements 206 do not all have the same properties. In a contemplated embodiment, not every ED element 206 on a single energy director 200 has the same shape, along with or instead of varying heights. As with varying heights, the benefits of varying the shape between the ED elements 206 are again discussed below in connection with the welding sub-process of method 400 of Fig. 4. In general, the advantages also relate to an advantageous channeling of the welding energy - e.g., the ultrasonic vibrations - initially through primary ED elements, while in an early phase of welding less or not all of it passes through the secondary ED elements, and through the secondary elements, while less or not all of it passes through the primary ED elements in a subsequent phase of welding. II.C. Algorithm and operating procedure - Fig. 4-11

[0050] Now moving on to the fourth figure shows Fig. 4 illustrates an exemplary algorithm by means of a flowchart 400 that defines a method for (a) determining an energy director such as the energy director 200 of Fig. 2 and (b) weld workpieces together by applying welding energy to a proximal workpiece at the identified location such that it is channeled through and melts the novel energy director as desired. The result is an effective and efficient weld, and a more accurate and robust weld joint is formed with less overall cycle time, energy, and energy director material compared to conventional techniques.

[0051] In some embodiments, the algorithm controls only some aspects of the method, such as the sub-process that Fig. 4 is assigned the reference number 406. In another, it controls, for example, the workflows 406 and 408, and in others, the workflows 404, 406, 408, and 410. The workflows are again described further below.

[0052] Although joining two workpieces is primarily described herein, the number is presented as an example and more than two pieces may be joined in accordance with the teachings of the present disclosure.

[0053] It should be appreciated that the steps of method 400 are not necessarily presented in any particular order, and that performing some or all of the steps in an alternative order is contemplated. The steps have been presented in the illustrated order for ease of description and illustration. Steps may be added, omitted, and / or performed concurrently. It should also be appreciated that the illustrated method 400 may be terminated at any time.

[0054] In certain embodiments, some or all of the steps of this process and / or substantially equivalent steps are performed or at least initiated by a computing device, such as a processor executing computer-executable instructions stored or embodied in a computer-readable medium. Furthermore, any one or more steps of the process may be performed, initiated, or otherwise enabled by automated machinery, such as robotics.

[0055] The schedule from Fig. 4 outlined procedure 400 is now additionally based on the tools and components from Fig. 5-10. Properties of the elements shown, such as shape, size, and number, are presented to facilitate this description.

[0056] The method 400 begins 401 and the flow proceeds to block 402 in which an energy director such as the one shown in Fig. 2 shown direction sensor 206 is positioned between the workpieces. Fig. 5 shows an example positioning of the energy director between adjacent workpieces.

[0057] In one contemplated embodiment, the energy director is formed in a sub-process of molding at least one of the workpieces. For example, a mold in which the first workpiece is compression-molded may include recesses and / or protrusions configured (e.g., sized and shaped) to form the energy director at a desired location on the vehicle.

[0058] The workpieces to be welded together, as provided, may be similar or dissimilar. Regarding dissimilar workpiece materials, one workpiece may be, for example, a plastic or other polymer, and the other may be steel, aluminum, an alloy, or another metal, etc. Thus, the teachings of the present disclosure may be used, for example, to join a polymer (e.g., a polymer composite) to another polymer or to join a polymer to a metal.

[0059] In one embodiment, the material contains polyethylene. In one embodiment, the material contains polyethylene terephthalate (PET), high-density polyethylene (HDPE), and / or ethylene vinyl alcohol (EVOH).

[0060] In one embodiment, at least one of the workpieces being joined contains a polymer. At least one of the workpieces may contain synthetic or inorganic molecules. Although the use of so-called biopolymers (or green polymers) is increasing, petroleum-based polymers are still much more common.

[0061] The material of one or both workpieces may also contain a recycled material such as a polybutylene terephthalate (PBT) polymer, which is approximately eighty-five percent post-consumer polyethylene terephthalate (PET).

[0062] In one embodiment, one or both of the workpieces contain a type of plastic. In one embodiment, the material contains a thermoplastic.

[0063] In one embodiment, one or both of the workpieces contain a composite material. For example, in one embodiment, one or both of the workpieces contain a fiber-reinforced polymer (FRP) composite, such as a carbon fiber reinforced polymer (CFRP) or a glass fiber reinforced polymer (GFRP). The composite material may, for example, be a glass fiber composite. In one embodiment, the FRP composite is a plastic / metal hybrid composite.

[0064] In some implementations, the material contains a polyamide grade polymer, which may be generically referred to as a polyamide.

[0065] In addition, the material of one or both workpieces may contain polyvinyl chloride (PVC).

[0066] In one embodiment, the material contains acrylonitrile butadiene styrene (ABS).

[0067] In one embodiment, the material contains a polycarbonate (PC).

[0068] Additionally, the material of one or both workpieces may contain some type of resin. Examples of resins include a glass fiber polypropylene resin (PP resin), a PC / PBT resin, and a PC / ABS resin.

[0069] The workpieces can be preheated and compression-molded before welding.

[0070] In most manufacturing processes, more than one weld is created to join two adjacent workpieces. Thus, the positioning in step 402 may include positioning multiple energy devices between the workpieces.

[0071] Continue with Fig. 4, with the energy director(s) positioned between the workpieces, the process proceeds to step 404, where the assembly is positioned adjacent to the welding system. This process may include moving the workpiece / ED assembly toward the welding system and / or moving aspects of or the entire welding system toward the location.

[0072] The initial rough positioning of step 404 may include positioning an ultrasonic horn of the system near an estimated or assumed location of the energy director to be used in the first weld.

[0073] The flow proceeds to the energy director fine placement subprocess or routine 406. As in Fig. 4, the localization routine 406 contains several substeps identified by superscript indices - ie 406 1-5- are distinguished. From step 404, the method proceeds in particular to the first routine step 406 1 in which the welding head or the sonotrode (e.g. the ultrasonic servo sonotrode such as the sonotrode tip of the example from Fig. 1) is lowered. The sonotrode is moved towards the next workpiece - ie the workpiece that is closest to the sonotrode, such as in Fig. 1 and Fig. 5 - lowered.

[0074] The lowering is in Fig. 6. The coarse positioning of step 404 typically does not position the sonotrode directly over the energy director. Instead, the sonotrode typically initially lands only partially positioned over the energy director, as indicated by path 604 in Fig. 6, or not at all above the direction indicator, as indicated by the path 602 in Fig. 2. The target path is the third 606, which, as further described below, is determined by one or more iterations of the routine 406 1-5 is achieved.

[0075] The sinking operation 406 1 is carried out according to the operation of a controller that is directly or indirectly connected to the welding sonotrode. Features of an exemplary controller are shown in Fig. 11 and described further below. For example, the controller controls a rate at which the sonotrode is lowered toward the proximal workpiece. The controller may, for example, control or be part of a robotic device or robot that controls the movement of the welding sonotrode.

[0076] In the next step 406 2In routine 406, the controller determines whether a resistive force received from the workpiece at the welding horn indicates that the horn has been lowered to a local endpoint. The controller determines this based on feedback (e.g., from a force sensing element) indicating a force applied by the workpiece 101. 1 The controller receives the force information from a sensor (not shown in detail), which may be part of or connected to the welding system, or part of or connected to the automatic robotic device that controls the movement of the welding sonotrode.

[0077] If in step 406 2 If it is determined that the sonotrode has not reached its local end point, the algorithm flow returns as shown in Fig. 4, to the first routine step 406 1This occurs, for example, while the sonotrode is being lowered and has not yet touched the workpiece. It also occurs when the sonotrode has touched the workpiece but has not yet been lowered enough to receive a sufficient amount of resistance force from the workpiece.

[0078] If in step 406 2 If it is determined that the sonotrode has reached its local end point, the algorithm flow goes to step 406 3in which the controller determines a displacement the horn has undergone to reach the point or otherwise determines a location of the endpoint—e.g., a vertical distance from some reference system. The displacement may be determined, for example, by a transducer directly or indirectly connected to the horn. In one embodiment, the system is configured to take displacement measurements continuously at short time intervals or otherwise rapidly while the horn is descending. Further, the system is configured to compare the determined regular displacement values to a target displacement value that is continuously determined or at short regular intervals or otherwise rapidly while the horn is descending.

[0079] In step 406 4the controller determines whether the displacement or the vertical position of the sonotrode corresponding to the local endpoint indicates that the sonotrode has been lowered to a target location of the workpiece location - ie, the location of the location with the energy director between the workpieces and directly completely below the welding sonotrode.

[0080] The controller is programmed or calibrated with data that identifies values or ranges of horn displacements or positions that correspond to expected or probable positions of the horn relative to the target location of the workpiece. For example, the data indicates that the horn is in a given vertical position within an error window or error range when the horn has touched the target position because the horn's threshold force has been more likely to oppose it.

[0081] This is because the workpiece location is thicker where the energy director is located, or at least the upper workpiece doesn't yield as much to the horn when the energy director is there. If the horn pushes at a location on the workpiece that is not above the energy director, the horn can push further down the workpiece before the horn finally experiences the threshold resistance force. The data indicates where the horn is based on the horn displacement relative to the threshold force—e.g., in laboratory tests, it can be generated above or not above the energy director. Furthermore, the data can provide an indication of how far the horn is from the energy director based on the horn displacement relative to the threshold force.

[0082] This concept is illustrated by Fig. 6 and Fig. 7 further described.

[0083] As mentioned, Fig. 6 three exemplary paths 602, 604, 606. In a first lateral position above the proximal workpiece 101 1 the sonotrode descends along the first exemplary path 602. Since the energy director 200 is nowhere near a line of the path 602 when the sonotrode touches the workpiece 101 1 touches, the workpiece, which is not restricted by any energy director, yields or shifts more than if the director were present. Thus, the sonotrode can move further downwards before the predetermined threshold force is absorbed by the workpiece 101 1 counteracts the downward movement of the sonotrode.

[0084] Fig. Figure 7 is a graphical representation of the three Fig. 6 shown paths. More precisely, Fig. 7 shows a graph 700 with a y-axis 702 representing the welding sonotrode displacement and an x-axis 704 indicating the lateral or orthogonal position of the sonotrode. The first column 706 corresponds to the first path 602 of Fig. 6. Accordingly, the displacement is very high, since the path 602 is not above and not relatively close to the energy director 200 in Fig. 6 is.

[0085] The second column 708 in Fig. 7 corresponds to the second path 604 from Fig. 6. Accordingly, the displacement is lower, but still not as low as it should be, since path 606 is still not directly and completely over the energy director 200. In some embodiments, the energy director is not rigid and rather has a certain degree of flexibility. Thus, the sonotrode counteracts less counterforce when it (e.g., on the second path 604) impacts a portion of the workpiece 101. 1is lowered that is not completely above the energy director, because less of the director acts to resist the downward movement of the horn. When the horn is lowered (e.g., along the third path 606) directly above the director, more (i.e., all) of the energy director is below the workpiece where the horn is lowered, so more of the director opposes the downward movement of the horn, and the workpiece thus displaces less before experiencing the threshold reaction force.

[0086] The third pillar 710 in Fig. 7 corresponds to the third path 606 from Fig. 6. Accordingly, the displacement is relatively low since the path 606 is directly above the energy director 200, which limits further sinking of the sonotrode.

[0087] Continue with Fig. 4, assuming that the welding sonotrode is at a first lateral position corresponding to the first path 602 in a first iteration of the routine 406, the controller would then in step 406 3 determine that the sonotrode has moved by a relatively large amount - e.g. the first relatively large displacement 706 - to reach the end point.

[0088] In the next step 406 4 The controller determines whether the displacement (e.g., displacement 706 corresponding to the first path 602) indicates that the sonotrode is directly over the energy director. Since the displacement in this first iteration is relatively high (e.g., displacement 706), the controller concludes, based on the preprogrammed data (e.g., from previous laboratory tests), that the sonotrode is not directly over the director. Thus, the algorithm proceeds from decision 406. 4 to step 4065 where the controller determines a next lateral location to move the sonotrode to for a next descent and measurement.

[0089] In one embodiment, the determination in step 406 includes 5 where the sonotrode should be moved for the next drop of the sonotrode, the consideration of the last step 406 4 specific displacement. If the last displacement (e.g., displacement 706) is very high, for example, the lateral distance to move the horn for the next drop would be higher. If the last displacement is low—e.g., very close to that if the horn were directly over the energy director—the subsequent distance to move the horn for the net drop would be much smaller.

[0090] After repositioning the sonotrode in step 406 5 the steps 406 1 up to 406 5 repeated.

[0091] If the iteration in step 406 4 results in a sonotrode displacement at or below a threshold or to the target displacement, the controller concludes that the sonotrode has been lowered directly over the energy director. For example, the sonotrode is running based on Fig. 6 and Fig. 7, when the sonotrode along the third path 606 from Fig. 6 is lowered, over a minimal displacement 710, which is also in Fig. 7 specified sleeper displacement 712. The displacement values at or below the sleeper displacement 712 may be referred to as a displacement tolerance range.

[0092] In response to the provision at 406 4 that the sonotrode has only moved by a desired displacement (e.g. 710) to reach the threshold resistance force, and the sonotrode directly above the workpiece thus onto the workpiece 101 1has been lowered, the algorithm flow then proceeds from the energy director location routine 406 to the welding step 408.

[0093] In step 408, welding energy is applied to the proximal workpiece 101 at the specific location directly above the energy director. 1 For ultrasonic welding, the energy contains high-frequency ultrasonic vibrations that are excited and emanate from the welding sonotrode.

[0094] As described above, the energy director is designed so that the welding energy initially passes through some energy director elements (ED elements) (206) more or completely than through others. For example, in the multi-height embodiments, the energy would initially pass through the longer ED elements 206. 1 and not by the shorter elements 206 2 go, since the longer elements the distal workpiece 101 2touch, which creates a path between the workpieces 101 1 , 101 2 generated. Since the shorter elements form the distal piece 101 2 do not touch and since there is therefore no way for the energy to travel through the shorter elements to the distal piece 101 2 the energy would not flow freely through the shorter ED elements at this point.

[0095] If the welding energy is increased by the longer ED elements 101 1 the longer elements and the workpieces adjacent to the longer elements are melted first. This phase is Fig. 8 shown.

[0096] In welding operations, and especially in ultrasonic welding, heat is generated from intermolecular friction at and between the energy directors and the workpieces where the welding energy (e.g., RF vibrations) passes. This heat causes the director and the workpieces to melt, creating the joining weld.

[0097] At least because of the weight of the proximal workpiece 101 1 and due to the downward force of the sonotrode, the assembly is subjected to a certain amount of pressure. In some embodiments, the sonotrode is configured (e.g., spring-loaded) and / or controlled to exert a downward force on the proximal workpiece 101 during welding. 1 Thus, the upper workpiece 101 1 lowered while the ED elements melt.

[0098] After the longer elements have melted further, a Fig. 9 shown subsequent phase, in which the longer ED elements 206 1 are sufficiently melted so that the shorter ED elements 206 2 the distal workpiece 101 2 touch.

[0099] Since the longer ED elements 206 1 are at least partially melted and the shorter ED elements 206 2 are not yet melted and the lower workpiece 101 2 not yet touched, the shorter ED elements offer 206 2 at this point a path with less resistance for the welding energy (e.g. HF oscillations) than the longer ED elements 206 1 .

[0100] This channels the welding energy from the Fig. 9 shown phase of the welding process 408 essentially or at least more by the shorter elements, which they and the workpieces 101 adjacent to the shorter elements 1 , 101 2 melts.

[0101] During solidification, the molten sections between the workpieces form weld nuggets, with these welds connecting the workpieces 101 1 , 101 2 For embodiments in which a generally ring-shaped energy director (e.g., the director 206 of Fig. 2) is used, the resulting weld can generally also be annular. An example weld is shown in Fig. 10 (where the welding point without the workpieces 101 1 , 101 2 , which holds the weld together).

[0102] As stated, it has been found that an annular weld can be as strong as continuous welds (i.e., welds without a central void). Specifically, a predominant amount of the holding force generated by a continuous or continuous weld is provided by an outer ring portion of the weld, with a central portion of the weld contributing comparatively little holding force. Thus, a weld without the central portion can be formed with less energy and perhaps less time than a continuous weld (one without a central void) without sacrificing joint strength.

[0103] After a predetermined period of time, the application of welding energy is stopped and the sonotrode is removed from the proximal workpiece 101 1The system is preprogrammed with the time for applying the welding energy. The timing can be determined, for example, in laboratory tests.

[0104] Finally, based on Fig. 4, the controller determines in step 410 whether any other welds need to be made. If so, flow returns to step 404, where the horn is repositioned to locate a next energy director in the location routine 406. Once the next energy director has been located, flow returns to the welding operation 408, and so on.

[0105] Although two ED element heights are disclosed, in a contemplated embodiment, the energy director includes more than two heights, so that a corresponding number of welding phases is greater than two.

[0106] As mentioned above, instead of, or in conjunction with, the height difference between the ED elements 206, the elements may have a shape difference that controls where and when the welding energy is channeled, thereby controlling which parts of the energy director melt in a first phase and which in a second phase. Although two ED shapes are provided as a primary example, more than two ED shapes, and thus a corresponding number of welding phases, are possible.

[0107] Although two primary welding phases - e.g. a first phase during which the longer ED elements 206 1 channel and melt the welding energy, and a second phase during which the shorter ED elements 206 2channeling and melting the welding energy - have been described, as mentioned, although the energy is transferred more strongly through the shorter element in the second phase, the energy can be transferred further to a lesser extent through the longer elements, since it is still between the workpieces 101 1 , 101 2 are intact.

[0108] The present welding technique 408 results in the ED elements melting progressively, high and then short, in a desired time interval.

[0109] In addition, technique 408 enables the use of less energy to perform the weld than would be required if the weld director were devoid of any ED elements or if each ED element were the same height and shape. For example, if the energy director included ten (10) identical ED elements, sufficient energy would be required to channel the energy through all ten elements simultaneously over a long, single phase. Conversely, if the energy director included five longer ED elements and five shorter ED elements, only sufficient energy would be required to channel the energy through the five longer elements in the first phase, and this energy would be less than the energy level of the previous example in which the energy was channeled through all ten identical ED elements.In the second phase, generally only the energy required to channel the energy through the five shorter elements is required, and this energy level is also lower than the energy level of the previous example, in which the energy had to be channeled through all ten identical ED elements. Furthermore, theoretically, the sum of the energy applied in the first phase and the second phase is less than the total energy required for the arrangement that would have the ten identical ED elements. II.D. Example Controller - Fig. 11

[0110] Fig. Figure 11 schematically illustrates features of an exemplary controller, such as a computing device. The controller is shown in Fig. 11 by reference numeral 1100. As indicated, the controller 1100 may control or be part of a robotic device 1102.

[0111] As shown, the controller 1100 includes a storage or computer-readable medium 1104, such as a volatile medium, a non-volatile medium, a removable medium, and a fixed medium. The term computer-readable media and variations thereof, as used in the specification and claims, refers to tangible, non-transitory storage media.

[0112] In some embodiments, storage media includes volatile and / or non-volatile media, removable media, and / or fixed media such as, for example, random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), solid-state memory or other storage technology, CD-ROM, DVD, BLU-RAY or other optical disk storage, magnetic tape, a magnetic disk storage, or other magnetic storage devices.

[0113] The controller 1100 also includes a computer processor 1106 that is or can be connected to the computer-readable medium 1104 via a communication link 1108, such as a computer bus.

[0114] The computer-readable medium 1104 contains computer-executable instructions 1110. The computer-executable instructions 1110 may be executed by the processor 1106 to cause the processor, and thus the controller 1100, to perform any combination of the functions described in the present disclosure. These functions are described in part above in connection with Fig. 4 and in the supporting illustrations from Fig. 1-3 and 5-10.

[0115] In one contemplated embodiment, the controller is in communication with one or more remote devices 1112. For example, a central computer or service in the manufacturing plant may communicate with the controller 1100, such as to provide instructions to the controller 1100 and / or receive feedback (e.g., operational reports) from it.

[0116] In addition, the computer processor 1106 is connected or to be connected to at least one interface 1112 to enable communications between the controller 1100 and any other local components 1114, such as, for example, sensor devices such as the force sensors mentioned above.

[0117] Additionally, the interface 1112 is configured to enable communications with any remote device 1116.

[0118] The interface 1112 may include wired connections and / or wireless connections—e.g., transceivers, transmitters, and / or receivers—to communicate with the local components 1114.

[0119] To communicate with the remote components 1116, the interface 1112 includes a short-range transceiver (or transmitter and / or receiver) and / or a long-range transceiver (or transmitter and / or receiver).

[0120] The remote components 1116 may be databases, servers, other processors, other storage media, and / or other computing devices, such as other systems in a manufacturing plant that transmit instructions to and / or receive data (e.g., performance reports) from the controller 1100.

[0121] Although the interface 1112 is shown as being entirely part of the controller 1100, it or any one or more aspects thereof may be partially or entirely a part of the controller 1100. The interface 1112 or any one or more aspects thereof may be partially or entirely external to the controller 1100 and connected or connectable thereto. III. Benefits of implementation

[0122] One advantage of this technology is energy savings, as less energy is required to locate the energy directors.

[0123] It also saves time because less time is spent locating the energy directors.

[0124] Such efficient, effective, and robust welding processes support the increased use of polymer components that must be joined with similar materials (e.g., polymer composite / polymer composite joint) or with dissimilar materials (e.g., a polymer / metal joint, etc.). Related benefits of using such materials include weight reduction, performance improvements, and corrosion resistance.

Claims

[1] Method for locating a welding energy director (200) for welding together a plurality of workpieces (101 1 , 101 2 ) in a region of the energy director (200), comprising: Positioning a workpiece assembly in preparation for making one or more approaches to locate the energy director (200), the workpiece assembly including a proximal workpiece (101 1 ) of the several workpieces, a distal workpiece (101 2 ) containing a plurality of workpieces and the welding energy director (200) located therebetween; and Executing a localization subroutine by a computing device as a controller, said localization subroutine comprising: Moving a welding sonotrode (106) from a first lateral position above the proximal workpiece (101 1) which is closest to the welding sonotrode (106), in a lowering movement towards the proximal workpiece (101 1 ); Determine in a location determination whether a through the proximal workpiece (101 1 ) applied to the welding sonotrode (106) and received by the welding sonotrode (106) indicates that the welding sonotrode (106) has been lowered to a local endpoint, wherein the location determination further comprises the controller determining a displacement value reached by the welding sonotrode (106) when the resistance force exerted by the proximal workpiece (101 1 ) the resistance force exerted on the welding sonotrode (106) has reached a threshold value; and Lateral repositioning of the welding sonotrode (106) for a further, laterally offset approach movement towards the proximal workpiece (101 1) and repeating the subroutine method steps of lowering movement and location determination until, upon reaching the threshold value of the resistance force, the displacement value achieved by the welding sonotrode (106) is smaller than the threshold displacement, whereupon it is determined that the energy director (200) is located directly below an area in which the welding sonotrode (106) was positioned. [2] The method of claim 1, wherein positioning the energy director (200) comprises forming the energy director (200) with the proximal workpiece (101 1 ) in a compression molding process for the first workpiece. [3] The method of claim 1, wherein moving includes moving the welding sonotrode (106) and / or the workpiece assembly taking into account an estimated or known location of the energy director (200) such that the welding sonotrode (106) is relatively close to the energy director (200). [4] The method of claim 1, wherein the energy director (200) is a multi-altitude director comprising first energy directing elements (206 1 ) having a first height (212), and second energy-directing elements (206 2 ) having a second height different from the first height (212). [5] Method according to claim 4, wherein the energy directing elements (206 1 , 206 2 ) are configured to channel welding energy through the device in a predetermined manner, wherein the predetermined manner comprises channeling the energy through the first energy directing elements (206 1 ) in an initial phase of the welding process, while in the initial phase no energy is generated by the second energy directing elements (206 2 ) contains. [6] The method of claim 5, wherein the predetermined manner comprises channeling the energy through the second energy directing elements (206 2) in a subsequent phase of the welding process.

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