Abstract:
A method, for repairing a discrepant weld in a workpiece arrangement including at least two workpieces, comprising positioning a mechanical intermediary adjacent the discrepant weld and inserting the intermediary through the discrepant weld and into at least a distal workpiece of the two workpieces, wherein upon insertion, a proximate surface of the intermediary is exposed at a proximate side of the workpiece arrangement. The method further includes delivering weld energy to the intermediary. The intermediary is configured, and the weld energy provided, so that energy passes through the intermediary in a pre-determined manner. Energy passing through the intermediary in the pre-determined manner generates heat in material of the workpieces causing the material to melt at an arrangement interface. The method further comprises allowing or causing the material melted to cool, wherein the melted material, when cooled, forms and/or strengthens a robust joint connecting the workpieces.

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to joining workpieces robustly and, more particularly, to apparatus and methods for repairing, using a specially-configured mechanical intermediary, flawed or discrepant welds in workpiece arrangements including at least two workpieces, wherein at least one each set of workpieces includes a polymeric composite. 
     BACKGROUND 
     In automotive manufacturing, polymeric composites are being used increasingly due to favorable characteristics including being lightweight, highly-conformable or shapeable, strong, and durable. Some composites are further colorable and can be finished to have most any desired texture or finish. 
     Increased use in automobiles includes, for instance, in instrument and door panels, lamps, air ducts, steering wheels, upholstery, truck beds or other vehicle storage compartments, upholstery, external parts, and even engine components. Regarding engine components, and other under-the-hood (or, UTH) applications, for instance, polymers are configured, and being developed continuously, that can withstand environments being hot and/or chemically-aggressive. 
     Regarding external parts, such as fenders, polymers are being developed to have online paintability and high heat and chemical resistance over longer periods of time. 
     Many other potential uses for polymers and, particularly polymeric composites, in automotive applications continue to be developed. 
     With this trend, finding ways to efficiently and effectively join polymer components is becoming progressively important. Compression molding and post-mold joining techniques—e.g., ultrasonic welding—are being used more commonly, for instance. 
     In ultrasonic welding, two workpieces are joined, wherein one or both includes a polymeric composite or other polymer. With reference to the figures, and more particularly the first figure,  FIG. 1  shows schematically a conventional ultrasonic welding arrangement for joining two workpieces  102 ,  104  using a welding tool  106 . 
     The tool  106  includes multiple parts, such as an arm  108  and an ultrasonic vibration applicator, or horn  110 . The arm  108  is connected to other components, such as a pneumatic or servo actuator (not shown in detail) for controlling vertical displacement of the horn  110 . 
     For welding, components of the tooling  106  are moved to a proximate workpiece  102  of the two workpieces as indicated by arrow  112 . 
     For the ultrasound technique, the workpieces  102 ,  104  are held together between the horn  110  and an under structure  114 , such as an anvil. The pieces  102 ,  104  are maintained under pressure while ultrasonic vibrations are applied to pieces for the welding. 
     The vibrations create frictional heat, initially at faying interfaces (i.e., tool-to-workpiece, workpiece-to-workpiece), and then intermocular friction in the composite material, causing the material to melt. When the melting occurs at the interface  116 , the workpieces are joined there by molecular bonds (e.g., fusion or covalent bonds) of the molten material. 
     Sometimes, flawed, or discrepant welds are formed. A discrepant weld, generally, is any weld differing undesirably from a target weld configuration. A common flaw is that a weld is undersized, or otherwise less robust than desired. In one scenario, a discrepant weld can, for instance, not reach the inter-piece interface  116  as needed for joining the workpieces  102 ,  104  together robustly. 
     In another scenario, a discrepant weld reaches the inter-part interface  116 , but does not bridge the interface  116  as needed for joining the  102 ,  104  workpieces together robustly. 
     In the example of  FIG. 3 , the weld  202  barely reaches the interface  116 , and does not connect robustly to the distal workpiece  104 . 
       FIG. 2  shows a subsequent stage  200  of the arrangement wherein the horn  110  provides welding energy  202 —e.g., high-frequency (HF) acoustic vibrations—to the workpieces  102 ,  104 . As with the downward force  112  indicated in  FIG. 1 , a downward force  206  may be applied in connection with the operation of  FIG. 2 . A molten workpiece material nugget  204  begins to form, in response to the heating adjacent the horn  110 , as the vibration is transmitted from the horn into the workpiece  102 . 
       FIG. 3  shows the arrangement, after the erred welding in which the insufficient, or discrepant, weld  300  is formed. There are many factors that can contribute to the weld  300  being insufficient. For instance, workpiece material may be contaminated, one or both of the workpieces may be overly-thick, one or both workpieces may be improperly positioned or not held robustly and so moving (due, e.g., to improper or malfunctioning fixture), improper process variables [e.g., frequency, amplitude, clamping force, or time (e.g., insufficient time)], and/or other conditions may be present. 
       FIG. 3  shows the weld horn  106  being withdrawn from the newly completed, but insufficient, weld  300 . 
       FIG. 4  shows an example sufficient, desired, weld  400 . The weld  400  bridges the inter-piece gap  116  significantly, joining the pieces  102 ,  104  robustly. 
     With continued reference to the discrepant weld  300  ( FIG. 3 ), an attempt to simply re-weld the weld  300 , using the same tooling and process, would be ineffective at least because sufficient frictional heat will likely not be able to be generated again at the same faying interfaces of the workpiece, as modified, for re-welding. More particularly, the workpiece structure, especially at a surface or perimeter of the previously-welded zone, would have become too constraint to generate sufficient welding heat again. 
     Attempting to repair a weld  300  by adding additional welds around it is also usually not practical due to limited space, material, time, and energy, as well as for cosmetic considerations. 
     A surely undesirable alternative is to scrap the workpieces  102 ,  104  in which the discrepant weld  300  is formed. 
     Hypothetically, some workpieces improperly joined could be recycled, somehow, but resources would need to be dedicated to determining whether parts can be recycled, recycling the parts that can be, and handling the parts that cannot. 
     Yet another alternative is conventional mechanical fastening of the workpieces  102 ,  104  together instead of welding, or after a partial weld has been identified. The workpieces can be screwed together, or connected by nuts and bolts, for instance. These connections have shortcomings including possible lack of durability and mechanical strength. The connection may not be robust due to the fastener connecting to already insufficient joint material. Another shortcoming is that the fastener may need to be threaded in order to maintain connection to the workpiece material over time, and the threading may be insufficient for connecting to some materials, such as metal or polymeric composites. 
     SUMMARY 
     The present technology relates to apparatus and methods for repairing flawed or discrepant welds created in a workpiece arrangement including two workpieces. The workpieces can include, e.g., a polymeric composite. Other example materials are described below. 
     In a primary implementation, the repairing technique increases a size and/or robustness (e.g., strength) of an existing insufficient weld. 
     The repair process includes positioning a specially-designed mechanical intermediary component to extend between the workpieces  102 ,  104 , for receiving subsequent welding energy in a repair welding repair routine. 
     The repair routine may be based on resistance-heating (e.g., Joule heating) generated by electrical current as the welding energy. The electrical current is applied via two or more electrodes, as described further below. 
     Benefits of the present technology include saving energy and cost associated with conventional efforts such as scrapping flawed products or adding new welds. Average cycle time, over repeated iterations of welding, such as in a manufacturing plant environment, is also reduced by avoiding such efforts. 
     The resulting product is more robust, having a stronger joint connecting the workpieces. 
     Other aspects of the present invention will be in part apparent and in part pointed out hereinafter. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates schematically aspects of a conventional ultrasonic welding arrangement including a welding horn and two workpieces prior to ultrasonic welding. 
         FIG. 2  shows the arrangement of  FIG. 1  as welding is commenced to join the workpieces together. 
         FIG. 3  shows the arrangement as welding is completed, yielding a discrepant weld—e.g., undersized and/or shaped in a non-robust manner. 
         FIG. 4  shows the arrangement of  FIG. 1  after an example preferred welding, resulting in a complete weld. 
         FIG. 5  illustrates schematically a cross-sectional view of a novel weld-repair tool, including a specially-configured mechanical intermediary, for guiding welding energy (e.g., electrical current) in a secondary welding routine. 
         FIG. 6  shows a top plan view of the specially-configured mechanical intermediary of  FIG. 5 . 
         FIG. 7  shows the arrangement of  FIG. 3 , including the discrepant weld, and the specially-configured mechanical intermediary being moved toward a final, secondary-welding, position with respect to the discrepant weld and the workpieces. 
         FIG. 8  shows the arrangement after the specially-configured mechanical intermediary has been placed in its secondary-welding position. 
         FIG. 9  shows introduction of resistance-welding electrodes so that each electrode contacts a portion of the specially-configured mechanical intermediary. 
         FIG. 10  shows the arrangement following the positioning of  FIG. 9 . 
         FIG. 11  shows initial activity in the arrangement as welding energy in the form of electrical current is passed between the electrodes, through conductive parts of the specially-configured mechanical intermediary, creating new molten material by resistive (e.g., Joule) heating, initially at interfaces between the specially-configured mechanical intermediary and the workpieces. 
         FIG. 12  shows the arrangement of  FIG. 11  following further application of the electrical current in completing the repairing resistive welding routine. 
         FIG. 13  shows the electrodes being withdrawn from the repaired product, including the robust repaired weld. 
     
    
    
     DETAILED DESCRIPTION 
     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 expansively to embodiments that serve as an illustration, specimen, model or pattern. 
     The figures are not necessarily to scale and some features may be exaggerated or minimized, such as to show details of particular components. In some instances, well-known components, systems, materials or methods have not been described in detail in order to avoid obscuring the present disclosure. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure. 
     While the description includes a general context of computer-executable instructions, the present disclosure can also be implemented in combination with other program modules and/or as a combination of hardware and software. The term application, or variants thereof, is used expansively herein to include routines, program modules, programs, components, data structures, algorithms, and the like. 
     Applications can be implemented on various system configurations, including single-processor or multiprocessor systems, microprocessor-based electronics, combinations thereof, and the like. In certain embodiments, some or all operations (e.g., controlling horn application) are performed by, or at least initiated by a computing device, such as a processor executing computer-executable instructions stored or included at a computer-readable medium. And any one or more steps of the process can be performed, initiated, or otherwise facilitated by automated machinery, such as robotics. 
     I. General Overview of the Disclosure 
     An apparatus and methods for repairing flawed or discrepant welds, such an insufficient ultrasonic weld, created between workpieces are described. In one embodiment, at least one of the workpieces, e.g., a top, proximate, one of the workpieces, includes a polymer, such as a polymeric composite. Below, other example polymer-based materials, and other possible workpiece materials are described. 
     In situations in which a discrepant (e.g., insufficient) weld is formed, the repairing technique operates to, using a specially-designed and configured mechanical intermediary, increase the size, fusion, and/or robustness of the discrepant weld, and provide a peel-stop back-up connection. 
     In operation, the specially-configured mechanical intermediary is positioned in the part having the discrepant weld so that the intermediary extends between both workpieces and is exposed at opposing locations to a surface of the workpiece arrangement. Resistive-welding electrodes are positioned subsequently so that each electrode contacts one of the exposed portions of the specially-configured mechanical intermediary. 
     Welding energy in the form of electrical current is passed between the electrodes, through conductive parts of the specially-configured mechanical intermediary, creating new molten material by resistive (e.g., Joule) heating, initially at interfaces between the specially-configured mechanical intermediary and the workpieces. In one embodiment, the intermediary includes insulative material surrounded by the conductive material, causing the current to focus at exterior portions of the intermediary for promoting the resistive heating efficiently adjacent the surfaces of the exterior portions. 
     After the secondary welding, the specially-configured mechanical intermediary is locked robustly in place by hardening new molten workpiece material formed by the resistance welding. The hardening new material also creates a robust weld with, and distinct from, the intermediary. 
     As also provided, specially-configured mechanical intermediary also acts as a peel stopper after the joining process, during use of the resulting product. The intermediary, in this function, provides an extra layer of protection against either of the workpieces moving (e.g., peeling) away from the other of the workpieces. 
     The resulting product, including the new weld material, and specially-configured mechanical intermediary, creates a connection between the workpieces that is much more robust than the original, discrepant weld. 
     By the present technology, material is saved and cost reduced. Material and cost are reduced by, e.g., obviating conventional efforts such as scrapping or recycling flawed products, or adding new welds. 
     The system components, algorithm, and operations are described further below with reference to the figures. 
     II. Process, Tooling, and Workpieces—FIGS.  5 - 13   
     The present technology is now described with reference to example systems, tooling, and workpieces. The figures are referenced to facilitate understanding of the technology and not to limit scope thereof. 
     Reference to directions herein, such as upper, lower, up, down, and lateral, are provided to facilitate description of the present technology but does not limit scope of the technology. A description in which the horn is described as descending down upon a proximate workpiece is not limited, for example, to the horn moving vertically downward in the earth, or environment, frame. The horn in this case can be moving from left to right, for example, in the environment frame. 
     Turning again to the figures, and more particularly, to the fifth figure,  FIG. 5  shows a custom weld-repair tool  500  according to the present technology. 
     The repair tool  500  is a specially-configured mechanical intermediary. The intermediary  500  is used in response to determining that a discrepant weld is present. The determination can be made in any appropriate manner. In one embodiment, the determination is made using teachings of one or both of U.S. Pat. No. 8,439,247 and U.S. Pat. Appl. Publ. No. 2011/0108181, which are incorporated herein by reference. 
     Because determining existence of a discrepant weld can be made during and/or immediately following discrepant-weld formation, the repair process can be commenced immediately thereafter, without need to relocate the workpieces  102 ,  104 . 
     The arrangement is in one embodiment configured so that the specially-configured mechanical intermediary  500  is positioned and/or inserted into a final position manually, such as by assembly-plant personnel. In one embodiment, one or both acts are positioned by automated machinery—e.g., robotics. In one embodiment one or both acts are performed by both, person and machinery, and in one embodiment by either, selectively. 
     With continued reference to  FIG. 5 , the specially-configured mechanical intermediary  500  includes an upper, head portion, or head  502  and a lower, protruding, portion  504 . 
     The head  502  has a first, top, or proximate contact surface  506 . In the resistive-welding routine referenced above, an electrode will contact this surface  506 . 
     The head  502  can have any of a wide variety of shapes and sizes. In the example shown, the head  502  has a generally round, or circular, top profile, as can be seen in the top plan view of the intermediary  500  in  FIG. 6 . Other example profile shapes include oval, elliptical, square, or other rectangle, or other shapes having one or more straight sides. 
     It is contemplated that various specially-configured mechanical intermediaries can be sized and shaped to match shapes of various common types of discrepant welds. Personnel or machinery can select from amongst the options, accordingly. For instance, when an exposed orifice to a discrepant weld is generally round, then a generally circular specially-configured mechanical intermediary  500 , such as that in  FIG. 6 , is selected for the case. When an exposed orifice to a discrepant weld is generally oval, then a generally oval specially-configured mechanical intermediary  500  is selected for the case. And so on. As noted, the selection could be made manually, e.g., by assembly-plant personnel, and/or by automated machinery—e.g., robotics. 
     In the illustrated embodiment, the head  502  includes an angled side  508  extending to an edge  510  of the head  502 . With the angled side being as shown, a width of the head  502  increases from a top (e.g., at the first contact surface  506 ) of the head  502  toward a bottom of the head  502  (e.g., adjacent the edge  510 ). In one embodiment, the side  508  is angled in an opposite direction than that shown—i.e., the head width decreases from the top of the head toward the bottom of the head. 
     In one embodiment, the head  502  is a composite, such a by having a conductive shell  512 , or coating (e.g., an electrically-conductive shell) surrounding a generally insulative interior  514  (e.g., electrically-insulative interior), as shown in  FIG. 5 . Example electrically-conductive materials include any of various metals (aluminum, steel, brass, copper, etc.). Example electrically-insulative materials include rubber and plastic. In some embodiments, the head  502  is a solid or homogonous conductor. 
     The protrusion  504  also includes conductive material  512 . The protrusion  504  includes a conductor (e.g., electric and/or thermal conductor). Generally, the material of the protrusion  504  should be strong enough to pierce through the material of the workpieces  102 ,  104  in their hardened states (e.g., never melted, or melted and cooled and hardened). 
     In a contemplated embodiment (not shown in detail), the protrusion  504  is a composite, including external conductive material (or, ‘shell’ or ‘coating’) surrounding internal insulative material (e.g., an electrically-conductive shell or coating). Again, directing the electricity to the areas needed, the composite format, here regarding the protrusion  504 , may save time and energy in the repair process. 
     The composite format, i.e., conductive-insulative configuration, is designed to direct transmission of weld energy—e.g., electric current—through the intermediary  500  as desired. Generally, the transmission is directed to portions of the specially-configured mechanical intermediary  500  adjacent intermediary external surfaces so that the weld energy—e.g., electric current—effects heat generation (from, e.g., Joule heating) in the material of the workpieces  102 ,  104  adjacent the intermediary  500 , for curing the discrepant weld  300 . These characteristics and operations are described further below in connection with the resistance-welding routine. 
     By directing the electricity to the areas needed, the composite form may save time and energy in the repair process. The solid, or homogenous, forms may be less expensive. 
     The lower, protruding portion  504  of the specially-configured mechanical intermediary  500  can also have various sizes and shapes within the scope of the present technology, and, like the head  502 , is not limited to the size and shape illustrated. In one embodiment, the specially-configured mechanical intermediary  500  is sized and shaped so that, when the intermediary is inserted fully into a discrepant weld  300 , the top surface  506  is exposed at a proximate side of the workpieces  102 ,  104 , and a tip  516  of the protrusion  504  is exposed at a distal side of the workpieces. 
     A sufficient height of the portion  504  is needed in this implementation. A width, as with all aspects of the tool  500 , need be appropriate to transmit the welding energy—e.g., electrical current—as needed during a secondary welding routine. 
     In one embodiment, the protrusion  504  is sized and shaped to facilitate insertion of the tool  500  through the discrepant weld  300  and into the distal workpiece  104 , and to handle the secondary welding energy as desired. The handling can include, e.g., transferring electrical current received from the head  502  to the distal electrode  104  via the tip  516 , or transferring electrical current received from the distal electrode via the tip  516  to the head  502 , and therein causing workpiece material adjacent the protrusion  504  to heat (e.g., by Joule heating) and melt. 
     As shown in the figures, the protrusion  504  can include a tapered portion—i.e., a portion having width that tapers from, e.g., wider closer to the head  502  to thinner toward the tip  516 . In one embodiment, the tip  516  is pointed. In a contemplate embodiment, the tool  500  includes more than one protrusion for extending through the discrepant weld  300  and into at least the distal workpiece  104 . 
     An example shaping, sizing, and positioning for the tool  500  is shown in  FIG. 8 , for instance. 
       FIG. 7  shows schematically the custom weld-repair tool  500  being lowered, as indicated by arrow  700 , toward the proximate workpiece  102  of the workpieces  102 ,  104  joined by the discrepant weld  300 . 
     The workpieces  102 ,  104  welded together can be similar or dissimilar. One or both pieces include a polymer, such as in the form of a polymeric composite, for instance. Example workpiece materials are described in greater detail further below. 
     As described above, the tool  500  in one embodiments is sized and shaped to match, generally (exact shape match not required), a shape of the discrepant weld  300 . For instance, if the discrepant weld is generally round, then the generally circular intermediary  500  shown in  FIG. 2  is selected. 
     Positioning the specially-configured mechanical intermediary  500  as needed for subsequent welding (e.g., resistive welding) includes positioning the intermediary  500  so that it extends from top to bottom of the workpieces. A portion should be exposed at a top, and a portion should be exposed at a bottom, of the arrangement. The top surface  506  of the tool will be exposed at the proximate (e.g., top) side of the arrangement and a tip  516  of the protrusion  504  of the tool  500  will be exposed at the distal side of the arrangement. The tool  500 , including the protrusion and the head, are sized and shaped to accomplish this. 
     In a contemplated embodiment, assuming that sufficient energy (e.g., electrical current) is used in the secondary welding (e.g., resistive welding) welding routine, and depending on the distal workpiece  104  material, the tip  516  need not extend fully to the lower surface of the distal workpiece  104 —i.e., the tip  516  in this case need not be physically, or visibly, exposed—so long as the electrical current can still pass to, or from, the corresponding electrode  904 . 
     Positioning the specially-configured mechanical intermediary  500  includes forcing the protruding portion  504  of the intermediary to pierce at least the discrepant weld  300  and the distal workpiece  104 . If the discrepant weld  300  does not reach from a top, exposed surface all the way to the interface  116  in a robust manner, positioning the intermediary  500  may include pushing the intermediary past material of the proximate workpiece  102 . 
     As mentioned, the force for pushing the intermediary  500  into the workpiece arrangement can be provided by personnel or by automated machinery, such as using a hard rubber mallet. 
       FIG. 8  shows a positioning of the intermediary  500  in the workpiece arrangement. 
     With the specially-configured mechanical intermediary  500  positioned in the workpiece arrangement as provided, a secondary welding-energy applicator or device  900  is introduced, as shown by way of example in  FIG. 9 . The secondary welding-energy device  900  in some embodiments includes two electrodes  902 ,  904 . While the secondary welding-energy device  900  includes two components, in some embodiments, the secondary welding-energy device  900  includes one, or more than two components. 
     The electrodes  902 ,  904  are configured and arranged (e.g., connected to a source and a ground) to provide electrical current between them  902 ,  904  (the current is not visualized in the figures). The electrical current is provided for secondary welding—e.g., resistive welding—together of the workpieces  102 ,  104  using the intermediary  500 . 
     While resistive welding is described primarily herein as the secondary welding technique, it is contemplated as provided that other techniques (e.g., heating via introduced conductor tool) can be used for the secondary welding without departing from the scope of the present technology. 
       FIG. 10  shows the electrodes  902 ,  904  positioned for the secondary welding. As provided, the specially-configured mechanical intermediary  500  is positioned in the part having the discrepant weld so that the intermediary  500  extends between both workpieces and is exposed at opposing locations to a surface of the workpiece arrangement. 
     As also shown in  FIG. 10 , the resistive-welding electrodes  902   904  are positioned so that each electrode contacts one of the exposed portions of the specially-configured mechanical intermediary  500 —i.e., proximate surface  506  and distal tip  516 . 
     More particularly, the proximate electrode  902  of the secondary-welding device  900  is positioned adjacent and in contact with the proximate surface  506  of the mechanical intermediary  500 , as shown in  FIG. 10 . The distal electrode  904  of the secondary-welding device  900  is positioned adjacent and in contact with a distal portion, e.g., tip  516 , of the mechanical intermediary  500 , as also shown in  FIG. 10 . 
     With the secondary-welding device  900  in position, the secondary welding is commenced. In the primary example context, in which the secondary technique involves resistive welding, the operation involves beginning to deliver electrical current between the electrodes  902 ,  904 . 
     The system can be arranged so that the electrical current is passed from the first, or proximate, electrode  902  and through the mechanical intermediary tool  500  piercing the discrepant weld and workpieces  102 ,  104 , on its way to the second, or distal, electrode  904 . Or the system can be arranged so that the electrical current is passed to the first, or proximate, electrode  902 , via the mechanical intermediary  500  piercing the discrepant weld and workpieces  102 ,  104 , from the second, or distal, electrode  904 . 
     The electrical current passing between the electrodes  902 ,  904 , through conductive parts of the specially-configured mechanical intermediary  500 , causes, by resistive heating, melting of workpiece material adjacent the intermediary  500 . The resistive heating, and so the melting, generally occurs first at interfaces between the conductive portions  512 ,  504  and material of one or both workpieces. 
     While the secondary, repair, welding routine may include melting of the workpiece material that was previously melted, in the original welding (e.g., initial, ultrasonic welding of  FIG. 2 ), and subsequently cooled to some extent, it is expected that usually resistive heating and melting in the repair welding routine will occur predominantly in workpiece material that was not properly melted in the initial welding. Newly-melted workpiece material can also marry with any initially-melted material that is still at least partially molten or that is re-melted in the secondary welding routine. 
       FIG. 11  shows an example early stage of the secondary welding. As can be seen comparing  FIG. 11  against  FIGS. 7-10 , new molten material  1100 ,  1102  is being formed in this stage. The new molten material  1100 ,  1102  is formed, e.g., in part or completely, adjacent the shaft  504  and about the head  502 . Importantly, some of the new molten material  1102  is being formed at the interface  116 , and so joining, or further joining, the workpieces  102 ,  104 . 
       FIG. 12  shows an example subsequent stage of the secondary, repair, welding routine. As can be seen comparing  FIG. 12  with  FIG. 1 , more molten material  1200  has been formed. The melting continues to be focused adjacent the shaft  504  and about the head  502 . Melted material continues to form at the interface  116 , and so joining, or further joining, the workpieces  102 ,  104 . 
     When sufficient melting is accomplished, the secondary, repair, welding routine is complete. The secondary-welding device  900  is withdrawn from the repaired part  1300  as shown by arrows in  FIG. 13 . 
     In one embodiment, a set amount of energy, or time, corresponding to sufficient secondary welding is pre-determined, such as in laboratory testing. In this case, the secondary, repair, welding can be performed until the target energy level or time is reached. For instance, it may be determined that one second of secondary welding by electrical current is generally sufficient to repair the weld  300 , and so the secondary welding is performed for this amount of time. 
     With the secondary, repair, welding complete, the specially-configured mechanical intermediary  500  is secured, or locked, robustly in place by the hardening new molten workpiece material (e.g.,  1100 ,  1102 ,  1200 ) formed by the secondary welding. The hardening new material creates a robust weld with the intermediary  500 . 
     As noted, the specially-configured mechanical intermediary  500  can act as a peel stopper after the joining process. The tool  500  in this function, being secured in the workpiece arranged by the secondary welding process (as shown in, e.g.,  FIGS. 7-13 ), provides an extra layer of protection against either of the workpieces  102 ,  104  moving (e.g., peeling) away from the other of the workpieces  104 ,  102 . 
     The resulting part  1300 , including the new joint  1302  (robust weld material  1304  and specially-configured mechanical intermediary  500 ), creates a connection between workpieces that is much more robust than the original, discrepant weld. 
     The nature of the workpieces, referenced above, is described now in further detail. 
     The workpieces  102 ,  104  being welded together can be similar or dissimilar, as mentioned. Regarding dissimilar workpiece materials, one workpiece can be a plastic or other polymer, for instance, and the other can be steel, aluminum, an alloy, or other metal, etc. Thus, the teachings of the present disclosure can be used to join a polymer (e.g., polymeric composite) to another polymer, or to join a polymer to a metal, for instance. 
     In one embodiment, the material of the pieces  102 ,  104  includes polyethylene. In one embodiment, the material includes polyethylene terephthalate (PET), high density polyethylene (HDPE) and/or ethylene vinyl alcohol (EVOH). 
     In one embodiment, at least one of the workpieces  102 ,  104  being joined includes a polymer. At least one of the workpieces  102 ,  104  can include synthetic, or inorganic, molecules. While use of so-called biopolymers (or, green polymers) is increasing, petroleum based polymers are still much more common. 
     Material of one or both workpieces  102 ,  104  may also include recycled material, such as a polybutylene terephthalate (PBT) polymer, which is about eighty-five percent post-consumer polyethylene terephthalate (PET). 
     In one embodiment one or both of the workpieces  102 ,  104  includes some sort of plastic. In one embodiment, the material includes a thermo-plastic. 
     In one embodiment one or both of the workpieces  102 ,  104  includes a composite. For example, in one embodiment one or both of the workpieces includes a fiber-reinforced polymer (FRP) composite, such as a carbon-fiber-reinforced polymer (CFRP), or a glass-fiber-reinforced polymer (GFRP). The composite may be a fiberglass composite, for instance. In one embodiment, the FRP composite is a hybrid plastic-metal composite. 
     The material  102 ,  104  in some implementations includes a polyamide-grade polymer, which can be referred to generally as a polyamide. 
     Material of one or both workpieces  102 ,  104  may also include includes polyvinyl chloride (PVC). 
     In one embodiment, the material  102 ,  104  includes acrylonitrile-butadiene-styrene (ABS). 
     In one embodiment, the material  102 ,  104  includes a polycarbonate (PC). 
     Material of one or both workpieces  102 ,  104  may also comprise a type of resin. Example resins include a fiberglass polypropylene (PP) resin, a PC/PBT resin, and a PC/ABS resin. 
     The workpieces  102 ,  104  may be pre-processed, such as heated and compression molded prior to the welding. 
     As mentioned, and any of the operations can be performed, initiated, or otherwise facilitated by automated machinery, such as robotics. A robot (not shown in detail) can be configured and arranged (e.g., connected to the custom weld-repair tool  500 ) to control the lowering and/or insertion of the weld-repair  500 . The robot can be automated or controlled by automation embodied in, e.g., a computer or other electronic controller (not shown). 
     The controller, in one embodiment, includes a tangible computer readable storage device, or memory. The memory is programmed with (i.e., stores) computer-executable instructions, or code, that, when executed by a processor, such as a processor of the controller, causes the processor to initiate and control motion of the weld-repair tool  500 . 
     The controller can control a downward movement of the tool  500 , a total distance, or displacement, of the movement, and a velocity, or rate of displacement and direction (e.g., down or up). 
       FIG. 13  shows the resulting repaired product  1300 , including a repaired weld  1302 , and the custom weld-repair tool  500  being withdrawn therefrom. As this is happening, and once application of the electrical current applied in connection with  FIGS. 10-12 , the product  1300 , and especially the new, repaired, weld begins to cool and harden, solidifying the repaired weld  1302 . 
     The resulting weld  1302  ( FIG. 13 ), being a repaired version of the discrepant weld  300  ( FIG. 3 ), matches the example initially-robust weld  400  ( FIG. 4 ) better than does the discrepant weld  300  ( FIG. 3 ). 
     The repaired weld  1302  can have even better characteristics than the example initially-robust weld  400 . 
     The mechanical intermediary  500 , now a part of the repaired joint  1302 , also acts as a peel stopper after the joining process, as mentioned. More particularly, the intermediary  500  provides, during use of the resulting product, an extra layer of protection against either of the workpieces  102 ,  104  moving (e.g., peeling) away from the other of the workpieces. 
     III. Various Technology Features 
     Many but not all of the advantage of the present technology are outlined above. Some but not all are described in this summary. 
     Benefits of the present technology include saving material and cost associated with other conventional efforts to address situations in which a faulty weld is formed. 
     Cycle time and processing cost (electricity, robotic operations, etc.) are reduced, for instance, as time is not needed to determine how many new welds to create, and where, and to create such welds. 
     Cycle time and processing cost (electricity, robotic operations, etc.) can also be improved by avoiding scrapping of flawed products. 
     Recycling some workpieces is possible, but, resources would need to be dedicated to determining whether parts can be recycled, recycling the parts that can be, and handling the parts that cannot. 
     As another benefit, the resulting product is more robust, having a stronger joint between the workpieces. 
     The new joint, including the mechanical intermediary, also has the improved peel-stopping functions referenced above. 
     The benefits make welding in an assembling environment much more cost effective and results in lightweight, durable (e.g., corrosion-resistant), products—e.g., vehicle components and entire vehicle—having strong, robust, joints. 
     IV. Conclusion 
     Various 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 expansively to embodiments that serve as an illustration, specimen, model or pattern. 
     The figures are not necessarily to scale and some features may be exaggerated or minimized, such as to show details of particular components. In some instances, well-known components, systems, materials or methods have not been described in detail in order to avoid obscuring the present disclosure. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art. 
     The above-described embodiments are merely exemplary illustrations of implementations set forth for a clear understanding of the principles of the disclosure. Variations, modifications, and combinations may be made to the above-described embodiments without departing from the scope of the claims. All such variations, modifications, and combinations are included herein by the scope of this disclosure and the following claims.