Abstract:
The subject invention relates to a precision injection molding of multi-piece parts and the subsequent handling and assembly of those parts produced from the mold. In an exemplary embodiment, a surgical suture package with a top part and a bottom part is molded and assembled. In such a method and system, the top parts and bottom parts are first molded utilizing a family mold and then are transferred to a stacker. The stacker is able to stack the top part and bottom part on top of one another on a pallet. The parts are then transported to a welder in order to weld the top part and bottom part together. The completed surgical suture packages are then transferred to a magazine for storage and shippage.

Description:
RELATED APPLICATIONS 
     This patent application is a divisional of U.S. patent application Ser. No. 10/769,310, filed Jan. 30, 2004, the disclosure of which is expressly incorporated by reference herein. 
    
    
     BACKGROUND OF INVENTION 
     The subject invention relates to injection molding machines that are able to mold at least two separate distinct parts at the same time and relates, in particular, to methods and systems for retrieving and assembling the at least two molded parts into a completed product. The use of family molds have become common in the production of plastic parts. A family mold is a mold that forms at least two separate, distinct parts that are to be joined together to form a single product. However, a need still exists for an efficient and cost-effective process for removing the molded parts from mold and assembling them into a finished product. 
     A variety of mechanisms have been used to remove the molded parts from the family mold. For example, in U.S. Pat. No. 4,915,611, a receiver is used to transfer the molded parts to a container. A family mold is used to produce a number of molded articles. The receiver, having individual article receptors, mates with the molded articles in order to remove the articles from the mold and transfer the molded articles from the mold to a container. U.S. Pat. No. 4,976,603 also discloses a device for removing molded pieces from a stacked mold. A rotatable arm assembly with a suction cup is utilized to remove the molded pieces from the stacked mold. As the mold portions are moved from close to open, the at least one suction cup engages the molded pieces and rotates through a ninety degree arc. The suction cup then releases the work piece so that the molded work piece is dropped down a chute to a conveyor belt. 
     While these patents disclose methods for removing molded parts from a family mold, these patents do not disclose a method for not only molding and removing the parts from the mold stack, but also assembling the separate, distinct parts into a product and then transferring the product to a magazine and/or container for storage. By utilizing an automated process that not only molds the parts but also removes and assembles the parts, the subject invention is able to cut down on the manufacturing cost associated with molding and assembling multi-piece parts. This and further advantages will become more apparent from the following description and drawings. 
     BRIEF INVENTION SUMMARY 
     The subject invention relates to the field of injection molding. More particularly, the subject invention relates to precision and injection molding of multi-piece parts and the subsequent handling and assembly of the parts produced from the mold. One embodiment of the inventive molding and assembly process utilizes a system with at least one family mold. As used herein, a family mold is a mold that forms separate, distinct parts that are to be joined together to form a single product. The family mold in this embodiment has alternating rows of mold cavities for two separate and distinct parts. Thus, the two separate distinct parts are molded side-by-side to one another in the family mold. After a molding cycle is complete, the two different parts are removed from the mold and transferred to a stacker so that the two separate parts have the same configuration as they did in the family mold and are side-by-side on the stacker. In this embodiment, an unloader can be used to remove the two parts from the family mold and can transfer the two parts to a linear transporter. The linear transporter can then transfer the two parts to the stacker. 
     After obtaining the two distinct parts from the linear transporter, the stacker can rotate into a position that is directly above a pallet. In this position, the stacker can place the first set of parts on the pallet. After the first set of parts are placed on the pallet, the stacker can move laterally so that the second set of parts are located above the first set of parts. The stacker can then place the second set of parts on top of the first set of parts. By placing the second set of parts on top of the first set of parts, the system creates a set of loosely assembly products. 
     The loosely assembly products can then be delivered to a welder. The welder will weld the two separate parts together to form a completed product. The completed products can then be transferred to and loaded in a magazine for storage. A pick and place unit with a plurality of vacuum grip heads can be utilized to transfer the completed products to the at least one magazine. Such a system and method can be utilized for a variety of products that require multiple pieces that need to be stacked on top of one another and welded together. For example, as explained in more detail below, this system and method can be utilized to create surgical suture packages with a bottom part and a top part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows a bottom view of a top part of an exemplary product created by the inventive molding and assembly process; 
         FIG. 1B  shows a top view of a bottom part of the exemplary product manufactured by the inventive molding and assembly process; 
         FIG. 1C  shows the assembled exemplary product with the top part and bottom part joined together; 
         FIG. 2  shows a diagrammatic top view of a system with a dual injection mold and stacker used to produce the exemplary part of  FIG. 1C ; 
         FIG. 3A  shows a side perspective view of the dual injection mold of  FIG. 2 ; 
         FIG. 3B  shows a side perspective view of one of the molds that comprise the dual injection mold of  FIG. 3A ; 
         FIG. 4  shows a diagrammatic view of the system of  FIG. 2  during the injection mold cycle; 
         FIG. 5  shows a diagrammatic view of the manifold of the dual injection mold of  FIG. 3A ; 
         FIG. 6  shows a diagrammatic view of the system of  FIG. 2  during the unloading cycle; 
         FIG. 7  shows a diagrammatic view of the system of  FIG. 2  during the transfer of the top parts and bottom parts to the stacker; 
         FIG. 8  shows a front view of the stacker of  FIGS. 2 ,  4  and  7 ; 
         FIG. 9  shows the stacker of  FIG. 8  after the top parts and bottom parts have been transferred to the stacker; 
         FIG. 10  shows the stacker of  FIG. 9  being rotated so that it can interact with a pallet; 
         FIG. 11  shows the stacker of  FIG. 9  positioned directly above the pallet; 
         FIG. 12  shows a pick and place unit removing fully assembled products from the pallet; 
         FIG. 13  shows the completed products being delivered to a magazine for storage and shippage. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1C  shows an exemplary product created by the inventive molding and assembly process. As shown in  FIGS. 1A-1C , the exemplary product is a two piece riveted package  10  for surgical sutures. The product includes a top part  12  (shown in  FIG. 1A ) with a plurality of rivet pins  16  and a bottom part  14  (shown in  FIG. 1B ) with a plurality of rivet holes  18 . Top part  12  and bottom part  14  each also have at least one pilot hole  19 . When top part  12  and bottom part  14  are joined together, plurality of rivet pins  16  extend from the top part through plurality of rivet holes  18  on the bottom part. A heating device welds rivet pins  16  so that the pins melt into rivet holes  18  and heat stake top part  12  to bottom part  14 . 
       FIG. 2  shows a top diagrammatic view of an exemplary system  100  used to perform the molding and assembly process of the surgical suture packages. As shown in  FIG. 2 , system  100  comprises a dual injection mold  20 . Dual injection mold  20  is a “stacked” mold consisting of two separate sets of molds A and B. Each of the molds A and B produce top parts  12  and bottom parts  14 .  FIG. 3   a  shows a side perspective view of molds A and B and  FIG. 3   b  shows a close up perspective view of mold A. As shown in  FIGS. 3   a  and  3   b , molds A and B each contain a plurality of mold cavities  30  for top parts  12  and a plurality of mold cavities  32  for bottom parts  14 . As can be seen in  FIG. 3   b , mold cavities  30  for top parts  12  and mold cavities  32  for top parts  14  are positioned side-by-side to one another so that each of the molds A and B have alternating, parallel columns of mold cavities  30  for the tops parts and mold cavities  32  for bottom parts. 
     Referring to  FIGS. 2 and 3   a , dual injection mold  20  comprises a stationary side  22 , a moveable opposite side  24 , and a moveable center  26 . Two helical screws  28  are positioned on each side of mold  20  and connect stationary side  22 , moveable opposite side  24 , and moveable center  26  to one another.  FIG. 4  shows a diagrammatic top view of the system during a mold cycle. As shown in  FIG. 4 , an operating means (not shown), such as an electric motor or any other means well known in the art, causes helical screws  28  to advance so that opposite side  24  moves towards moveable center  26  in the direction of arrows  34  until it contacts the movable center. Movable center  26  also moves in the direction of arrows  34  until it comes into contact with stationary side  22 . Dual injection mold  20  is collapsed such that the center  26  joins to both the stationary side  22  and the opposite side  24  to form mold cavities  30  for the top parts and mold cavities  32  for the bottom parts. 
     Once molds A and B are closed, an injector  54  pumps molten plastic (shown by arrow  38 ) through a center port  36 . Center port  36  runs through both molds A and B in order to fill the mold cavities  30  for the top parts and  32  for the bottom parts. Both molds A and B are family molds because each of the molds simultaneously mold separate, distinct parts that are to be joined together to form a single product.  FIG. 5  shows the layout of each of the molds A and B. As shown in  FIG. 5 , molds A and B each comprise a manifold  46  with center port  36 . A plurality of flow channels  40  branch off of centerport  36  and a plurality of runners  44  branch off of flow channels  40 . At the end of each runner  44  is a gate  42  that connects the runner to either mold cavity  30  or mold cavity  32 . Each gate  42  is associated with a pneumatic valve that opens and closes the gate. Manifold assembly  46  allows molten plastic to pass from center port  36 , through flow channels  40 , through runners  44 , through gates  42 , and into each of mold cavities  30  and  32 . Gates  42  are electronically controlled and are selectively opened at different times during the mold cycle in order to control the timing of the molten plastic entering each mold cavity, and thus ensuring that each part has a similar density as other parts in the mold. This process of opening and closing the gates to the mold at different times is often referred to as “sequential injection” molding. Once the mold cycle is completed and top parts  12  and top parts  14  are molded, each runner  44  is pinched off at each gate  42  by the pneumatic valve associated with the gate. In this embodiment, each mold A and B produce 16 parts during a mold cycle (8 bottom parts and 8 top parts). However, it is possible to create molds with more or less mold cavities in order to produce more or less parts. 
     After a mold cycle is complete, molds A and B open and molded top parts  12  and bottom parts  14  are removed from mold cavities  30  and  32 .  FIG. 6  shows a diagrammatic top view of system  100  during the unloading process. As shown in  FIG. 6 , helical screws  28  retreat in the direction of arrows  48  so that movable center  26  and opposite side  24  move away from stationary side  22 . Helical screws  28  ensure equal spacing of molds A and B when the molds are completely open. Once molds A and B are open, an unloader  50  is inserted between stationary side  22  and movable center  26  of mold A. Unloader  50  includes a plurality of vacuum grippers  52 . Vacuum grippers  52  contact molded top parts  12  and bottom parts  14  and form a vacuum between the grippers and the top parts and bottom parts. In this manner, vacuum grippers  52  secure these molded parts to unloader  50  in the same arrangement as they were molded in mold A (i.e., top parts  12  and bottom parts  14  are placed in four alternating, parallel columns so that each of the top parts is positioned next to one of the bottom parts). While only the removal of top parts  12  and bottom parts  14  from mold A is shown, the removal of the top parts and bottom parts from mold B will be accomplished with an essentially identical process. The number and location of vacuum grippers  52  on unloader  50  corresponds to the number and location of parts produced by mold A. Thus, in this embodiment, unloader  50  can remove and unload all 16 parts from mold A at one time. 
       FIG. 7  shows a diagrammatic top view of system  100  during the transferring process of top parts  12  and bottom parts  14  from unloader  50  to a linear transporter  56  and from the linear transporter  56  to a stacker  58 . As shown in  FIG. 7 , unloader  50  is removed from mold  20  and interfaces with linear transporter  56  so that the linear transporter receives top parts  12  and bottom parts  14  from the unloader. Linear transporter  56  also has vacuum grippers  52  that correspond in number and location to the vacuum grippers located on unloader  50 . Linear transporter&#39;s  56  vacuum grippers  52  contact and form a vacuum on top parts  12  and bottom parts  14  of unloader  50 , while the vacuum is removed from unloader&#39;s  50  vacuum grippers in order to release the top parts and bottom parts. The parts are arranged on linear transporter  56  just as they were molded within molds A and B (i.e., top parts  12  and bottom parts  14  are placed in four alternating, parallel columns so that each of the top parts is positioned next to one of the bottom parts). During the time that unloader  50  places the parts on linear transporter  56 , dual mold  20  collapses and molten plastic  38  is again delivered to the molds A and B and the molding process begins again. 
     Still referring to  FIG. 7 , linear transporter  56  moves along a path  60  and delivers top parts  12  and bottom parts  14  to stacker  58 .  FIG. 8  shows a front view of stacker  58 . As shown in  FIG. 8 , stacker  58  includes a plurality of vacuum cups  62  for holding top parts  12  and bottom parts  14 . Referring back to  FIG. 7 , linear transporter  56  moves along path  60  until top parts  12  and bottom parts  14  come into contact with vacuum cups  62 . When stacker  58  receives parts from the linear transporter, it is in a vertical position. Vacuum cups  62  form a vacuum on top parts  12  and bottom parts  14  while the vacuum from the vacuum grippers  52  of linear transporter  56  is removed to release the top parts and bottom parts. Vacuum cups  62  are arranged on stacker  58  so that top parts  12  and bottom parts  14  are held on the stacker in the same pattern as the parts are held on linear transporter  56 .  FIG. 9  shows stacker  58  after top parts  12  and bottom parts  14  are transferred to stacker  58  from linear transporter  56 . As shown in  FIG. 9 , top parts  12  and bottom parts  14  are positioned in four alternating, parallel columns of top parts and bottom parts, so that each top part is positioned next to one of the bottom parts. 
     Still referring to  FIG. 9 , stacker  58  is positioned on a shaft  64  that can be rotated 360 degrees in both the clockwise and counterclockwise direction by an electrical motor or a variety of other means well known in the art. After receiving top parts  12  and bottom parts  14  from linear transporter  56 , shaft  64  and stacker  58  rotate 90 degrees, so that the stacker is in a horizontal position and interacts with pallet  66 .  FIG. 10  shows shaft  64  and stacker  58  being rotated so that the stacker can interact with pallet  66 . As shown in  FIGS. 7 and 10 , pallet  66  includes two distinct rows of assembly nests  70 . Each assembly nest  70  contains tapered pilot pins  72  that are designed for insertion into pilot holes  19  of top parts  12  and bottom parts  14 . Pilot pins  72  also contact the edges of the top parts and bottom parts. In this manner, pilot pins  72  interacts with top parts  12  and bottom parts  14  in order to align the top parts with the bottom parts.  FIG. 11  shows stacker  58  positioned directly above pallet  66 . As shown in  FIG. 11 , stacker  58  rotates until it is positioned directly above pallet  66  in a horizontal position and top parts  12  are directly over assembly nests  70 . Once stacker  58  is in this position, it releases top parts  12 , so that each top part falls from the stacker and is received in one of assembly nests  70  of pallet  66 . As top parts  12  are released, pilot pins  72  engage the edges of top part  12  and are inserted into pilot holes  19  of the top part. In this manner, pilot pins  72  ensure that the top part is accurately positioned. 
     Still referring to  FIG. 11 , stacker  58 , next, shifts in the direction of arrow  74  so that bottom parts  14  are positioned directly over assembly nests  70  and top parts  12 . Stacker  58  then releases bottom parts  14  so that each bottom part falls from stacker and is received in one of assembly nests  70  of pallet  66 . In each assembly nest  70 , pilot pins  72  engage the edges of bottom part  14  and pass through pilot hole  19  to ensure that the bottom part is accurately positioned on top of top part  12 , so that the top parts&#39; rivet pins  16  extend through the bottom part&#39;s rivet holes  18  and are exposed upwards. In this manner, top parts  12  and bottom parts  14  are loosely assembled into packages  10  of surgical sutures. 
     Referring back to  FIG. 7 , once packages  10  are loosely assembled, pallet  66  proceeds along conveyer belt  80  and passes under ultrasonic welders  82 . After pallet  66  proceeds to ultrasonic welders  82 , shaft  64  and stacker  58  rotate back to their original position so that the stacker can receive the next load of top parts  12  and bottom parts  14  and another pallet  66  is put in position. Stacker  58  then repeats the above-described process to loosely assembly packages  10  on the new pallet. 
     Still referring to  FIG. 7 , pallet  66  travels down the conveyor belt  80  until it comes to a position below ultrasonic welders  82 . Ultrasonic welders  82  descend over loosely assembled packages  10  with their horns bearing on protruding rivet pins  16 . In this manner, ultrasonic welders  82  melt rivet pins  16  down into rivet holes  18  and heat stake the bottom part  14  to the top part  12 . Pallet  66  then moves past ultrasonic welders  82  along conveyer belt  80  into a position that allows assembled packages  10  to be removed from pallet  66  and stacked in a magazine for storage and subsequent shipping. 
       FIG. 12  shows a pick and place unit  90  removing fully assembled packages  10  from pallet  66 . As shown in  FIG. 12 , pick and place unit  90  has a plurality of vacuum grip heads  92  that contact and form a vacuum on each of the packages  10 . Pick and place unit  90  then removes each package  10  from each assembly nest  70  at the same time.  FIG. 13  shows pick and place unit  90  delivering completed packages  10  to magazine  94 . As shown in  FIG. 13 , each magazine  94  has four slots  96  that are each dimensioned to receive four completed packages  10  at the same time. Also shown by  FIG. 13 , pick and place unit  90  has enough vacuum heads  92  to place four rows of four packages (total of 16) in magazine  94 . Pick and place unit  90  loads packages  10  into each of magazine&#39;s  94  slots  96  by releasing its vacuum grip on packages  10 . Pick and place unit  90  repeats this process of transferring the packages  10  from pallet  66  and depositing the completed packages on top of each other in the magazine&#39;s slots  96  (visible suture package stacks are shown in  FIG. 13 ) until the magazine  94  is filled. 
     While a particular embodiment of the subject invention has been described in considerable detail herein, such is offered by way of a non-limiting example of the invention as many other versions are possible. For example, molds A and B, unloader  50 , linear transporter  56  and stacker  58  can be constructed to mold, produce, hold and transport any number of molded parts. Further, packages of surgical sutures do not have to be the product molded and assembled using this process. Rather, any product or package that requires any number of separate molded parts to be molded, stacked and assembled to one another can be manufactured by this process. Moreover, pallet  66  and pick and place unit  90  can be constructed to hold and transport any number of assembled products. It will also be appreciated by one skilled in the art that pallet  66  could be laterally shifted instead of stacker  58  in order to loosely assembly the top part  12  and bottom part  14  into a package  10 . It is anticipated that a variety of other modifications and changes will be apparent to those having ordinary skill in the art and that such modifications and changes are intended to be encompassed within the spirit and scope of the appended claims.