Patent Publication Number: US-2022226942-A1

Title: Bracket presenter for ultrasonic welder

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 63/138,102 filed on Jan. 15, 2021, and is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to a bracket presenter used for holding a sensor bracket during an ultrasonic welding process, for example, securing the sensor bracket to a bumper fascia. 
     BACKGROUND 
     Modern vehicles increasingly use sensors to detect objects around them, such as ultrasonic parking sensors. It is common for front and rear bumper facias to include numerous sensors mounted to the bumper fascia  2  by a sensor bracket  4 , which holds the sensor ( FIG. 1A ). As shown in  FIG. 1B , one type of typical sensor bracket  4  includes a face  6  from which a sensor holder  8  extends. The sensor holder  8  receives a generally cylindrically shaped sensor in a snap fit relationship. The face  6  of the sensor bracket  4  has a contour matching an inner face or B-side of the bumper fascia  2 . This face  6  is commonly ultrasonically welded to the bumper fascia  2 . 
     Referring to  FIG. 2 , an example ultrasonic welder is shown. The welder  10  is used in the example to join the face  6  of the sensor bracket  4  to a substrate  14 , such as a bumper fascia. A workpiece  14  is typically supported in a fixture or jig  12  during the ultrasonic welding process. The sensor holder  8  typically includes a passage should line up with a hole  90  in the workpiece  14  to center and expose a face of the sensor once fully assembled. 
     During installation of the sensor bracket  4  onto the bumper facia  2 , a sonotrode  20  selectively engages the face  6  to impart a vibration on the face sufficient to generate heat and melt the face  6  to the substrate  14 . In the example, the sonotrode  20  has one or more “points” 48 terminating in a geometry such as a PIP  50 . The sonotrode  20  is operatively secured to an ultrasonic converter  16 , which includes piezoelectric or other elements that vibrate (e.g., add up to 50 kHZ, for example) in response to a signal from a generator  22  that is commanded by a controller  24 . The sonotrode  20  may be designed to be used at other frequencies, if desired. A booster may be mounted between the converter  16  and the sonotrode to tune the frequency provided by the converter  16  to the sonotrode  20 . 
     During operation, a motion device advances the sonotrode  20  to engage the face  6  with the PIP  50  and maintaining contact pressure during the welding process. The motion device, for example, a pneumatic cylinder  26 , may be regulated by a valve  30  that selectively controls the flow of compressed air from an air source  28  to the cylinder  26  in response to a command from the controller  24 . Cooling air can be provided to the sonotrode  20  via an air line  29 . 
     The welder  10  can be configured in a different manner than described, for example, the motion device may be provided by a servomotor and/or robot. The sensor bracket  4  must be held in a desired orientation with respect to the substrate during the ultrasonic welding process. In one example, a sensor bracket  4  is loaded onto a bracket presenter  32 , for example of the type illustrated in  FIG. 3A-3C . The bracket presenter  32  has a first plate  34  that is mounted to a motion device, such as a pair of cylinders  33 . These cylinders  33  may be used to advance and retract the bracket presenter  32 , and thus the sensor bracket  4 , during the ultrasonic welding process. 
     It is desirable to allow slight movement between the sensor bracket  4  and the substrates  14  as the sensor bracket  4  mates with the substrate  14  to accommodate slight variations in tolerances between the parts. To this end, the bracket presenter  32  includes a second plate  36  that floats with respect to the first plate  34 . In one example, fasteners, pins, and/or springs may be used to loosely locate the first and second brackets  34 ,  36  with respect to one another while preventing significant rotation or displacement between the first and second plates  34 ,  36 . For example, as shown in  FIG. 3A  (broken view) and  FIG. 3B  (in phantom), a shoulder bolt  38  fixed relative to the first plate is received within a clearance hole  44  provided in the second plate  36 . This arrangement accommodates horizontal float during engagement of the sensor bracket and the workpiece  14 . But, undesirably, the plates are also permitted to floated when fully separated. A spring-loaded “pogo stick”  46  is provided between the first and second plates  34 ,  36  to enable the first plate, and thus the sensor bracket, to self-center with respect to the hole  90  in the workpiece. 
     A main body  40  extends from the second plate  36  in a direction opposite the first plate  34 . The main body includes mounts  42 , which engage locating features  52 , such as apertures and/or slots in the sensor bracket  4 . The various components illustrated in  FIGS. 3A-3C  are provided by numerous discrete parts that must be machined to size and assembled with respect to one another, adding great cost and complexity to the bracket presenter  32 . 
     SUMMARY 
     In one exemplary embodiment, a bracket presenter for an ultrasonic welder, the bracket presenter includes a one-piece first bracket portion and a one-piece second bracket portion that is mounted relative to one another. First and second tapered features are respectively provided by the first and second bracket portions. The first and second tapered features are nested relative to one another and engage in an extended position and are spaced from one another in a compressed position to provide a clearance that enables the first and second bracket portions to float lateral relative to one another. The first and second brackets are closer to one another in the compressed position than when in the extended position. 
     In a further embodiment of the above, the second bracket portion has a central body with mounts that are configured to support a sensor bracket in a desired orientation. The first and second bracket portions respectively include first and second plates. The bracket presenter further includes a set of first posts that extend from one of the first and second plates. Each of the first posts have a generally first conical shape and increase in diameter from the one of the first and second plates. A set of first tapered walls extend from another of the first and second plates. Each of the first tapered walls provide a first generally conical pocket that receives a corresponding one of the first posts. The bracket presenter further includes at least one spring that is arranged between the first and second plates. The first and second plates define a first height in an extended position. The first and second plates define a second height that is less than the first height in a compressed position in which the at least one spring is compressed. The first posts and their respective first tapered walls have a clearance between them in the compressed position and are in engagement with one another in the extended position. The first posts and first tapered walls provide the first and second tapered features. 
     In a further embodiment of the above, the one-piece first and second bracket portions and their respective first and second tapered features are each formed of 3D-printed layers. 
     In a further embodiment of the above, the second bracket portion has a central body that extends from the second plate on a side opposite the set of the first post or the set of first tapered walls. The central body is configured to receive a sensor bracket. 
     In a further embodiment of the above, the bracket presenter includes a second post that extends from the other one of the first and second plates. The second post has a second conical shape that increases in diameter from the other of the first and second plates. A second tapered wall extends from the one of the first and second plates to provide a second generally conical pocket that receives the second post. 
     In a further embodiment of the above, the set of first posts are provided on the first plate, and the second post is provided on the second plate. 
     In a further embodiment of the above, the at least one spring includes a pair of springs. One of the pair of springs circumscribes a corresponding one of the first posts. 
     In a further embodiment of the above, at least one of the first and second plates includes the springs integral with the corresponding one of the one-piece first and second bracket portions. 
     In a further embodiment of the above, a spacer is provided between at least several coils of the at least one spring to generate a preload that ensures engagement between the first posts and their respective first pockets in the extended position. 
     In another exemplary embodiment, a method of securing a sensor bracket to a substrate, the method includes mounting a sensor bracket to a bracket presenter that has first and second bracket portions that are movable relative to one another and with a spring that is arranged between the first and second bracket portions. The method further includes advancing the sensor bracket toward a substrate and engaging a hole in a substrate with an end of the second bracket. The method further includes moving the first and second bracket portions toward one another and compressing the spring to allow the second bracket portion to float relative to the first bracket portion. The moving step includes decoupling first and second tapered surfaces that are respectively provided by the first and second bracket portions. The method further includes locating the sensor bracket relative to the hole with the end. The method further includes seating the sensor bracket against the substrate, ultrasonically welding the sensor bracket to the substrate, and retracting and separating the bracket presenter from the sensor bracket. 
     In another exemplary embodiment, a method of manufacturing a bracket presenter, the method includes printing a first bracket portion with a first tapered feature, printing a second bracket portion with second tapered feature that is configured to selectively cooperate with the first tapered feature between extended and compressed bracket presenter positions, and providing a spring between the first and second bracket portions. 
     In a further embodiment of the above, the spring provides the step which includes printing the spring between the first and second bracket portions. 
     In a further embodiment of the above, the spring circumscribes the first and second tapered features. 
     In a further embodiment of the above, the spring printing step is performed during at least one of the first and second bracket portions printing steps such that the spring is integrally formed with the at least one of the first and second bracket portions. 
     In a further embodiment of the above, the method includes the step of inserting a space into the spring subsequent to the printing steps. 
     The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1A  illustrates an example prior art bumper fascia having a sensor with a sensor bracket. 
         FIG. 1B  illustrates an example prior art sensor bracket. 
         FIG. 2  schematically illustrates a common ultrasonic welder. 
         FIGS. 3A-3C  illustrate a prior art bracket presenter used to hold a sensor bracket during an ultrasonic welding process. 
         FIG. 4  is a side view of the disclosed bracket presenter with a sensor bracket mounted thereon. 
         FIG. 5  is a cross-sectional view of the bracket presenter shown in  FIG. 4  without the sensor bracket. 
         FIG. 6  is a cross-sectional view of the sensor bracket shown in  FIG. 5  without springs for clarity. 
         FIG. 7  schematically illustrates a spring spacer. 
     
    
    
     The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
     DETAILED DESCRIPTION 
     Referring to  FIGS. 4-7 , an example bracket presenter  54  includes first and second bracket portions  56 ,  58  and/or one or more springs  64  that are formed simultaneously during a 3D-printing process using, for example, a polymer such as a fiber reinforced nylon. The bracket presenter  54  may also be formed from other materials, if desired. Multiple 3D-printed layers are laid down to form the first and second bracket portions  56 ,  58  to provide one-piece, integral structures that are unitary and are able to move relative to one another, but also include capture features that limit their travel relative to one another during the ultrasonic welding process described above. By “unity” it is meant that the first and second bracket portions are retained with respect to one another without the need for further assembly. This structural relationship avoids the many separately machined and secured parts of the prior art, while providing additional advantages not found in traditional bracket presenters. 
     The bracket presenter  54  is manufactured by printing the first bracket portion  56  with a first tapered feature (e.g., first posts  66 ). At the same time, the second bracket portion  58  is printed with a second tapered feature (e.g., tapered walls  72 ) that are configured to selectively cooperate with the first tapered feature between extended and compressed bracket presenter positions (H 1 , H 2 ). It should be understood that the tapered features need not be provided by conical surfaces, rather that the points of engagement and disengagement between the first and second tapered features be of different sizes to permit coupling and decoupling of the first and second bracket portions  56 ,  58  from one another. The first bracket portion  56  may be the fixed part and the second bracket portion  58  may be the floating part, or vice versa. 
     In one example, a spring  64  is printed about, or circumscribing, each of the first and second tapered features to provide a compact design. The spring(s)  64  can be printed while the first and second bracket portions  56 ,  58  are printed such that the spring(s)  64  is integrally formed with the at least one of the first and second bracket portions  56 ,  58 . It is desirable for the first and second tapered features to engage one another when the first and second bracket portions  56 ,  58  are in the extended position (H 1 ). This enables the bracket presenter  54  to be positively positioned for automated loading of the sensor bracket  4  onto the presenter. If the spring  64  is printed between the first and second bracket portions  56 ,  58 , then then there will be no preload on the spring  64  and the first and second tapered features will not be in full engagement. So, a spacer  96  ( FIGS. 5 and 7 ) is inserted between coils in the spring  64  subsequent to printing. 
     The bracket presenter  54  has the one-piece first bracket portion  54  and a one-piece second bracket portion  56  mounted relative to one another in one disclosed example. The second bracket portion  58 , which is the floating part in the example, has a central body  60  with mounts  62  configured to support the sensor bracket  4  in a desired orientation, as best shown in  FIG. 4 . The first and second bracket portions  56 ,  58  respectively including first and second plates, with the first plate secured to the sonic welder, and second plate supports the central body  60 . 
     The central body  60  has a tapered end  92  that enables the second bracket portion  58 , and thus the carried sensor bracket  4 , with respect to the substrate  2  as the tapered end  92  is inserted into the hole, the bracket presenter  5  is compressed and the second bracket portion  58  begins to float, as explained in more detail below. 
     A set of first posts  66  extend from one of the first and second plates, in the example, the second plate, to provide the first tapered features. Each of the first posts  66  has a generally first conical shape and increasing in diameter from the second plate in the example. A set of first tapered walls  72  extend from the other of the first and second plates, here, the first plate, to provide the second tapered features. Each of the first tapered walls  72  provide a first generally conical pocket that receives a corresponding one of the first posts  66  in a nested relationship. These complementary tapered surfaces provide a positive location when engaged with one another in the extended position H 1 . The first posts  66  and their respective first tapered walls  72  have a clearance  84  ( FIG. 6 ) between them in the compressed position H 2 , which enables floating of the second bracket portion  58  in all directions in plane perpendicular to the direction of compression as well as some wobble of the second bracket portion  58 . 
     At least one spring  64  is arranged between the first and second plates. In the example, the spring  64  is printed along with the first and second bracket portions  54 ,  56 . One or both ends may be integrally formed with (i.e., joined do as part of the printing process) the first and second bracket portions  54 ,  56 . Alternatively, the spring  64  may be printed uncoupled to either of the first and second bracket portions  54 ,  56 . In the example, a spring  64  circumscribes each first post  66 /first tapered wall  72  pairing. The spacer  96  can be located with respect to a recess  98  in one of the plates, as shown in  FIG. 5 . In this example, the spacer  96  is U- or C-shaped to accommodate the first post  66  during insertion of the spacer  96  into the recess  98 . 
     A second post  68  extending from the other one of the first and second plates, in the example, to provide further stability and robustness. The second post has a second conical shape increasing in diameter from the first plate in the example. A second tapered wall  74  is provided on the opposite plate to provide a second generally conical pocket that receives the second post. 
     Some or all of the first and second posts  66 ,  68  may have an end that acts as a stop to limit the relative travel between the first and second bracket portions  56 ,  58  from the extended position H 1  to the compressed position H 2 . The tapered features act as stops when engaged to limit travel when fully extended. Although three pairs of complementary structures are shown (one pair first post  66  and wall  72 , another first post  66  and wall  72 , and a second post  68  and wall  74 ) that provide the mating first and second tapered features, a bracket presenter may be used that only has one pair. Such a simplified configuration may be used where the sensor bracket  4  does not need to be positively located at the extended position. That is, one, two, three or more pairs of complementary structures may be used depending upon the application. 
     In operation, the sensor bracket  4  is secured to a substrate  2  with the sensor bracket  4  mounted to the bracket presenter  54 . The first and second bracket portions  56 ,  58  are movable relative to one another with the springs  64  arranged therebetween. The sensor bracket  4  is advanced toward the substrate  2 , and the hole  90  in the substrate  2  is engaged with the tapered end  92 . The first and second bracket portions  56 ,  58  move toward one another and compress the springs  64 , which creates clearances  84 , to allow the second bracket portion  58  to float relative to the first bracket portion  56 . This movement decouples the tapered surfaces between the first and second bracket portions, i.e., the first and second posts  66 ,  68  with respect to their first and second tapered walls  72 ,  74 . 
     As a result, the sensor bracket  4  is located relative to the hole  90  with the tapered end  92  so that the sensor bracket  4  can be seated against the substrate  2 . At this point, the sensor bracket  4  can be ultrasonically welded to the substrate  2  in the desired position, and the bracket presenter subsequently retracted. 
     The disclosed bracket presented provides a unique configuration that enables lateral floating of the first and second bracket portions  56 ,  58  during sensor bracket positioning, but also positive locating of the bracket presenter for automated loading of the sensor bracket onto the presenter. The design of the bracket presenter no only permits one-piece construction of each of the first and second bracket portions  56 ,  58 , but in such a manner that the portions and even the springs can be formed simultaneously further reducing presenter manufacturing time. 
     It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention. 
     Although the different examples have specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.