Abstract:
A novel method and apparatus for riveting a two-piece suture tray package. A two-piece suture tray assembly is provided having a top member and a bottom member. The top member has a top and a bottom, and plurality of rivet members extending down from the bottom of the top member. The rivet members have free ends. The bottom member has a top and a flat bottom surface, and a plurality of rivet receiving openings extending therethrough. A counterbore surrounds each rivet receiving opening in the flat bottom surface. An ultrasonic riveting apparatus is provided having a clamp member with a cavity, and an ultrasonic horn member having a flat bottom moveably mounted in the cavity The assembly is mounted in the riveting apparatus and engaged by the clamp member. The flat bottom of the horn member engages the free ends of the rivet members, and when energized by an ultrasonic generator, causes the free ends of the rivet members to deform into the counterbores, such that the free ends are flat and in alignment with the bottom surface of the bottom member.

Description:
TECHNICAL FIELD  
       [0001]     The field of art to which this patent application relates is methods for assembling packages, in particular, method of assembling packages for sutures  
       BACKGROUND OF THE INVENTION  
       [0002]     Packages for surgical sutures are well known in the art. The function of the package is to contain and protect the suture strand material, and any attached surgical needles, and to provide low-force, tangle-free dispensing when used by the health care professional in a surgical procedure. One type of package that is known in this art is a tray package having a suture channel. Suture is loaded into the package by winding the suture into a suture channel, typically having an oval configuration. Suture tray packages are disclosed in U.S. Pat. Nos. 6,047,815 and 6,135,272, which are incorporated by reference. It is preferable that the package dispense the suture strand in a form that is relatively straight, retaining a minimal amount of ‘memory’ of the coiled shape of the suture packaged in the suture channel.  
         [0003]     A further function of a suture package is to secure an attached surgical needle in a holding device, or ‘needle park’, which secures the needle in a readily accessible location with sufficient strength to withstand shipping and handling forces to which the package may be exposed prior to use, while presenting access to and easy removal of the needle by the surgeon. It is desirable that the package be relatively thin, so that an efficient quantity may be stacked together within the confines of a dispenser carton. A dispenser carton is typically limited in size by a conventional hospital operating room storage rack system.  
         [0004]     The package also must provide a substrate for appropriate and required labeling. It is also important that the package be readily manufacturable. Surgical sutures are cost sensitive, high volume, disposable products. Accordingly, the packaging should present maximum function for minimal cost.  
         [0005]     Packages designs that incorporate the previously-described features typically have intricate shapes that are best provided by a tray-like base component made from a precision plastic injection molding. Still more design features can be provided if the molded package has two components, a top member and bottom member. Advantages of a two-component design are that more shapes and features can be incorporated into the resulting assembly, thereby providing a better opportunity to achieve the package objectives. A further advantage of a two-piece design is that different materials may be used for the two components, for example, a flexible plastic for the top member embodying hinged doors, and a more slippery rigid plastic (e.g., styrene polymer), for the bottom member embodying a suture track that is sensitive to sliding friction.  
         [0006]     The assembly operation for a two-component package requires an efficient and secure method of joining the components. Typical attachment methods for molded plastic parts which are adaptable to full automation include, but not limited to, conventional ultrasonic welding, solvent or adhesive welding, various snap-together designs, and use of mechanical fasteners such as screws.  
         [0007]     Although the conventional methods and processes for attaching components of tray packages together are adequate for their intended purpose, there is a continuing need in this art for improved attachment methods and processing.  
       SUMMARY OF THE INVENTION  
       [0008]     Therefore, it is an object of then present invention to provide a process for joining together a two-piece tray package for surgical sutures.  
         [0009]     Another object of the present invention is to provide an attachment method for suture package moldings that is fast to apply, thereby not slowing down, for example, a connected molding machine or other piece of process equipment.  
         [0010]     Yet another object of the present invention is to provide a novel low manufacturing cost process, not requiring added parts or materials such as fasteners.  
         [0011]     Still yet another object of the present invention is to provide a novel process that minimizes the thickness of a suture tray package and that it provides a secure bond at critical locations on the package.  
         [0012]     Another objective of the invention is to provide a novel package assembly process that is compatible with high speed automated assembly machinery.  
         [0013]     Accordingly, a novel method of joining together a two-part suture package is disclosed. The novel method is preferably directed toward a method of riveting a two-component suture tray package, but may be used to assembly or join together other types of two-component packages. In the novel method of the present invention, a top component is provided. The top component has a top, a bottom, an outer periphery and a plurality of rivet members extending down from the bottom. The rivets having bottom ends. A bottom component is provided. The bottom component has a top, a substantially flat bottom, an outer periphery, a suture channel, and a plurality of rivet receiving holes extending through the bottom component for receiving the rivet members. There is a counter bore extending into the bottom of the bottom component around each rivet receiving hole.  
         [0014]     The top component and the bottom component are assembled together to form an assembly by substantially aligning the peripheries of the top and bottom components and aligning the rivet members of the top component with corresponding rivet receiving holes of the bottom member, and then moving the top and bottom components together such that the rivet members are substantially contained in the rivet receiving holes and counterbores surrounding the rivet receiving holes. An ultrasonic riveting apparatus is provided. The apparatus has a a frame. A clamp member is movably mounted to the frame. The clamp member has a cavity, a bottom surface, a top surface and openings in the top and bottom surfaces in communication with the cavity. A base is mounted to the frame for receiving the assembled bottom component and top component. The base has a top, a bottom, and a groove in the top for receiving the suture channel of the bottom component. An ultrasonic horn member is movingly mounted to the frame. The ultrasonic horn member has a substantially flat bottom surface. The ultrasonic horn member is moveable within the cavity of the clamp member. An ultrasonic generator connected to the horn member. The assembly is placed on the base member such that the bottom component is on top of the top component and the suture channel is substantially contained within the groove. The clamp member is moved to engage the bottom of the bottom member of the assembly. The ultrasonic horn member is moved through the cavity of the clamp member such that the bottom surface of the horn member engages the free end of each rivet member. And, the horn member is energized with sufficient ultrasonic energy for a sufficient period of time to effectively heat and deform the free ends of the rivets such that the free ends of the rivets are contained within the counterbores surrounding the rivet holes, and the ends of the rivets are substantially flat and in alignment with the flat bottom surface of the bottom component.  
         [0015]     Yet another aspect of the present invention is a novel ultrasonic riveting apparatus. The ultrasonic riveting apparatus has a frame. A clamp member is movably mounted to the frame. The clamp member has a cavity, a bottom surface, a top surface and openings in the top and bottom surfaces in communication with the cavity. A base is mounted to the frame, the base has a top, a bottom and a groove in the top. An ultrasonic horn member is movingly mounted to the frame. The ultrasonic horn member has a substantially flat bottom surface. The ultrasonic horn member is moveable within the cavity of the clamp member. The apparatus also has an ultrasonic generator connected to the horn member.  
         [0016]     These and other aspects and advantages of the present invention will become more apparent from the following description and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is an illustration of the suture package of the preferred embodiment, in plan view.  
         [0018]      FIG. 2  is an illustration of the suture package of the preferred embodiment, in elevation view through Section A-A of  FIG. 1 .  
         [0019]      FIG. 3  is an enlarged view of the suture track of  FIG. 2 .  
         [0020]      FIG. 4  is a plan view illustration of the top member.  
         [0021]      FIG. 5  is a sectioned elevation view of the top member of  FIG. 4  taken through section B-B.  
         [0022]      FIG. 6  is a plan view illustration of the bottom member.  
         [0023]      FIG. 7  is a sectioned elevation view of the bottom member of  FIG. 6  taken through section C-C.  
         [0024]      FIG. 8  is an enlarged view of a rivet hole in  FIG. 7 .  
         [0025]      FIG. 9  is an underside view of the bottom member illustrating the counterbores in the rivet holes.  
         [0026]      FIG. 10  is a sectioned elevation view of the top and bottom members aligned, prior to assembly.  
         [0027]      FIG. 11  is a sectioned elevation view of the top and bottom members nested and mounted on the riveting base.  
         [0028]      FIG. 12  is a plan view of the top and bottom members nested and mounted on the riveting base, with the bottom member partially cut away to illustrate rivet details.  
         [0029]      FIG. 13  is the illustration of  FIG. 12  with the footprint of the clamp and ultrasonic horn indicated by shaded areas.  
         [0030]      FIG. 14  is a sectioned elevation view of the riveting base and top and bottom members thereon of  FIG. 11 , with the clamp and the ultrasonic system illustrated.  
         [0031]      FIG. 15  is the sectioned elevation view of  FIG. 14  with the clamp engaged.  
         [0032]      FIG. 16  is the sectioned elevation view of  FIG. 15  with the ultrasonic horn lowered and bearing on the rivet posts.  
         [0033]      FIG. 17  is an enlarged view of one rivet and hole with counterbore of  FIG. 16 .  
         [0034]      FIG. 18  is a view of the  FIG. 17  enlargement illustrating the initial heat forming of the, rivet.  
         [0035]      FIG. 19  is a view of  FIG. 18  illustrating the rivet heat forming progressing, and the shape of the deformation thereof.  
         [0036]      FIG. 20  is a view of  FIG. 19  illustrating the end of the forming stroke, and completion of the riveting operation.  
         [0037]      FIG. 21  illustrates the view of  FIG. 20  after withdrawal of the rivet forming tooling and clamp, illustrating the flat surface with no gain in package thickness resulting from the riveting process. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]      FIG. 1  illustrates a plan view of a molded plastic suture package  20 , further illustrating a suture  1  and attached needle  2  mounted therein. The needle  2  is secured in a needle park  3  molded into the floor  4  of the package  20 . The outer periphery  10  of package  20  is seen to have substantially straight parallel sides  5  connected by opposed semicircular ends  6 . Inboard of the outer periphery and parallel thereto is an internal, enclosed suture channel  7  containing the coiled suture loops  8 .  
         [0039]     Referring to  FIG. 2 , which is an elevation view of section A-A taken through  FIG. 1 , and  FIG. 3 , an enlarged view of the suture channel end portion  23  of  FIG. 2  is illustrated.  
         [0040]     The package  20  is seen to have an injection molded top and bottom members  24  and  15 , respectively. Said bottom member  15  has a suture channel vertical outer wall  16 , floor  17 , vertical inner wall  18 , and a peripheral recessed groove  19  for a label panel (not shown).  
         [0041]     The top member  24  is seen to have a plurality of flexible doors  25  that form the suture channel top cover. The top member  24  also embodies the needle park (not shown) molded to the central base area. It is seen that the outer wall  16 , floor  17 , inner wall  18 , and the top cover doors  25  define a hollow channel cavity  28  containing the suture strands  26  contained therein.  
         [0042]     The bottom member  15  and top member  24  are molded in the same machine in multiple cavities simultaneously, and are joined together in an automated operation described hereinbelow.  
         [0043]      FIG. 4  illustrates a plan view of the molded top member  24 , prior to assembly to the package. Flexible doors  25  are disposed around the periphery thereof.  
         [0044]      FIG. 5  is an elevational, side view of section B-B taken through the top member  24  of  FIG. 4 . A plurality of molded rivet pins  30  are seen projecting from the underside thereof.  
         [0045]      FIG. 6  illustrates the bottom member  15  of the package, prior to package assembly. A plurality of rivet holes  31  projects through the base material  32  of the bottom member  15 . The location of the rivet holes  31  correspond to the rivet pins  30  of the top member  24  of  FIG. 5 . It is seen that the preferred embodiment illustrated comprises twenty-three rivet holes  31  spatially positioned at locations on the package bottom member  15  where secure clamping force is most beneficial to the package  20  function.  
         [0046]      FIG. 7  is an elevation view of section C-C taken through  FIG. 6 , and  FIG. 8  is an enlarged view of the section containing one example  35  of the rivet holes  31  seen in  FIG. 6 . It is seen that a counterbore  36 , molded into the thickness  39  of the package base material  32  surrounds the rivet hole  35 . The counterbore  36  is seen to have a depth  37  and diameter  38 . Each rivet hole  31  has a similar counter bore  36 .  
         [0047]      FIG. 9  is an underside view of the bottom member  15  of  FIG. 6  illustrating the rivet holes  31 , particularly pointing out rivet hole  35 , and the counterbores  36  coaxial therewith.  
         [0048]      FIG. 10  is an elevation view of the two sectioned package components  15  and  24  illustrated in  FIGS. 5 and 7 . In the assembly process of the preferred embodiment the assembly is inverted, with the bottom member  15  positioned on top, and top member  24  on the bottom as illustrated. The bottom member  15  is illustrated aligned with the top member  24  prior to assembly thereto.  
         [0049]     Referring to  FIG. 11 , the bottom member  15  is seen nested into the top member  24 , causing the plurality of rivet pins  30  to protrude through mating holes  31 , and the suture channel doors  25  of said top member  24  to likewise nest within the outside vertical wall  16  of the bottom member  15 . The assembly is seen mounted on the riveting base tool  45 , said tool having an oval channel  46  therein to provide clearance for the molded suture channel structure  47 . The riveting base tool  45  embodies a flat surface  48  to support the plurality of rivets  30 , providing a backup force thereon during the riveting process. The base tool  45  is illustrated in a sectioned elevation view taken through the plane A-A of  FIG. 1 . Said plane A-A defining the sectioned view of  FIG. 11  centrally cuts the end rivet  30  and rivet hole  31 , enlarged below for detailed illustration.  
         [0050]      FIG. 12  is a plan view of the bottom and top moldings,  15  and  24 , and the base tool  45  of  FIG. 11 , illustrating the bottom member  15  cut away along break line  49  to view the top member  24  therebelow. An oval clearance groove  46  for the suture channel  47  ( FIG. 11 ) is seen in the base  45 . Rivet holes with rivet posts protruding up therethrough  51  are seen on the bottom member  15 . Rivet pins  52  are seen protruding up from the top member  24 .  
         [0051]      FIG. 13  is the plan view of the riveting base  45  of  FIG. 12  with two shaded footprints illustrated thereover. Shaded area  58  is the area of the package suture channel  47  ( FIG. 11 ) over which a clamping force is placed during the riveting operation. Shaded area  59  is the footprint of the flat ultrasonic welding horn positioned to heat form the rivet pins.  
         [0052]     Please refer to  FIG. 14 , which illustrates a section D-D taken through the base  45  of  FIG. 13  with sectioned views of the damping tool  60  and ultrasonic horn  61  added thereabove.  
         [0053]     The ultrasonic horn  61  is seen to be energized by the conventional electronic ultrasonic generator  63 . The clamp  60  is an oval hollow centered structure with the horizontal cross section of the shaded area  58  of  FIG. 13 . The Ultrasonic horn  61  is a flat-bottomed solid member with the rounded end shape of the shaded area  59 ,  FIG. 13 . Said damp  60  and horn  61  are independently vertically moveable as indicated by the arrow  62 , and have a clearance space  66  therebetween. The base tool  45  is horizontally slideable by an indexing transfer mechanism (not shown) and is supported by the frame of the machine  55 , and thereby enabled to withstand downward forces.  
         [0054]      FIG. 15  illustrates the initiation of the riveting cycle. The clamp  60  descends as indicated by arrow  64 , exerting downward force on the suture track  65  around the periphery of the moldings, pressing same together and against the base tool  45  to assure there is no gap therebetween. The ultrasonic horn  61  remains in a vertical parked position.  
         [0055]      FIG. 16  illustrates the next sequence in the riveting cycle. The ultrasonic horn  61  is displaced vertically downward indicated by the arrow  70  until the bottom  10  surface  74  contacts the top of the rivet posts  72  and exerts a force thereon. Simultaneously the force by the clamp  60  illustrated by the arrows  71  is continued.  
         [0056]     Please refer to  FIG. 17 , comprised of an area  73  in  FIG. 16 , enlarged to illustrate one single rivet, which can be seen in detail during the riveting process. The description relating to said single rivet pertains to the full plurality of rivets simultaneously.  
         [0057]      FIG. 17  is an enlarged part of section D-D,  FIG. 13 , said section cutting through the rivet  72  and top and bottom package members  24  and  15  respectively. In  FIG. 17  the rivet  72  is seen entered through the rivet hole  78  in the bottom member  15 , said bottom member also having a counterbore  76  coaxial therewith. The upper surface  77  of the base  45  supports the rivet  72  as force is applied thereon.  
         [0058]     The ultrasonic horn  61  descends, bringing the underside surface  74  thereof  25  to contact the top  79  of the rivet  72 .  
         [0059]     The ultrasonic horn  61  can be driven downward by a pneumatic cylinder, servo driven slide, or other motion device. The downward force, indicated by arrow  75 , sensed by suitable force transducers that send a signal to the control system (not shown), is increased to a predetermined trigger value that is sufficiently effective to produce a desired riveted connection.  
         [0060]     Said trigger signal is programmed, through the control system, to initiate the heat cycle of the ultrasonic driver  63  for the horn  61  when the downward trigger force of the ultrasonic horn  61  is reached, thereby initiating heating of the rivet plastic material at the contact point  79 .  
         [0061]      FIG. 18  illustrates an enlarged view of  FIG. 17  as heating of the rivet post  85  continues. Collapse and heat forming  86  of said rivet post is seen as heat from the horn  61  is imparted by the bottom surface  74  and force indicated by arrow  80  at the contact area  87  continues.  
         [0062]      FIG. 19  illustrates the condition of  FIG. 18 , after further heat forming of the rivet  88  and downward movement of the ultrasonic horn  61  in the direction of arrow  89 . The counterbore  76  is sized with a depth  37  and diameter  38  ( FIG. 8 ) to contain the volume of reformed rivet material, seen in  FIG. 20 . Said counterbore  76  could be a countersink, or any volumetric geometric shape coaxial with the rivet hole  78  sized to contain the formed rivet material.  
         [0063]      FIG. 20  illustrates completion of the riveting process of  FIG. 19 . The rivet  88  is seen fully plastically formed  90  into and filling the counterbore  76  and rivet hole  78 . Some melting and fusing (welding) of the rivet and the plastic material of the counterbore may take place at the interface  91  thereof. At the end of the ultrasonic horn  61  rivet forming stroke, in the direction of the arrow  89 , the underside  74  of said horn contacts the surface  92  of the bottom member  15 , thereby resulting in the surface  92  having no added thickness dimension from the rivets therein. Said flat surface  92  is seen in  FIG. 21 , illustrating the end of the riveting cycle, and the ultrasonic  61  and clamp  60  raised in the direction of arrow  94 .  
         [0064]     The riveting process illustrated in the above enlarged views of one rivet is simultaneously applied to all rivets on the package, and possibly multiple packages ganged together in multiple part tooling. Forms of heating other than ultrasonic may be used, such as heated plates or punches. It is further seen that the orientation of the products and tooling described hereinabove is arbitrary, and could have been inverted or lateral, as long as the relative motions described are achieved. The round rivet cross section of the preferred embodiment could be rectangular, ellipsoid, triangular, or any other geometric shape. Further, welding or fusing of the two plastic materials in the top and bottom members need not take place, and the two members could be of different materials. The bottom member need not be plastic, but could be made from a number of rigid materials such as metal.  
         [0065]     An example of a conventional ultrasonic generator that can be used with the riveting apparatus of the present invention is a Bronson ultrasonic generator model No. 921AES manufactured by Branson Ultrasonics, Danbury, Conn., U.S.A. The amount of ultrasonic energy transmitted to the rivet members by the bottom of the horn member will be sufficient to effectively deform the rivet members into the counterbores on the bottom of the bottom component. The energy will vary depending upon the size and number of the rivet members and the material of construction of the rivet members.  
         [0066]     The top and bottom members of the tray package assemblies that are riveted using the process of the present invention are typically manufactured from conventional polymeric materials including high density polyethylene, polypropylene, polystyrene, polycarbonate and the like and the like. The top and bottom members may be manufactured from the same materials or different materials. The top and bottom members are preferably made by conventional injection molding processes, and may be made by other conventional manufacturing processes including thermoforming, machining and the like.  
         [0067]     The ultrasonic horn used in the apparatus and process of the present invention is made from conventional materials including aluminum, stainless steel and the like.  
         [0068]     Although this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.