Abstract:
A method and apparatus for assembling a first thermoformed workpiece, such as a tab closure, to a second thermoformed workpiece, such as a lid.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. patent application Ser. No. 10/605,263, filed Sep. 18, 2003, and U.S. Provisional Patent Application Nos. 60/319,560, filed Sep. 18, 2002 and 60/319,655, filed Oct. 29, 2002, all of which are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The invention relates to a disposable, reclosable lid having a closure tab for selectively closing a drink opening of the reclosable lid. More specifically, the invention relates to an apparatus and method for automatically assembling the closure tab to the lid. 
   DESCRIPTION OF THE RELATED ART 
   Disposable lids have long been used for closing the top of a beverage container, especially for beverages that are purchased “to go,” such as from a fast-food restaurant, for example. The disposable lids used with containers for heated drinks such as coffees and the like are often provided with a closure tab that the user can manipulate to selectively close a drink opening in the lid, thus permitting the user to drink the heated beverage when desired while otherwise keeping the drink opening closed to reduce the convective cooling of the beverage and reducing the spilling of the beverage as it moves in response to the user moving the cup. 
   Disposable lids of this nature are typically made by thermoforming a suitable plastic, such as High Impact Polystyrene (HIPS). The thermoforming process has the advantage of being able to produce high-quality, low-cost lids at high volumes as compared to other manufacturing techniques such as injection molding, which can make more complex shapes than thermoforming but generally has lower production rates and higher tooling costs. 
   For most thermoformed, reclosable lids, the tab closure is integrally formed as part of the cover, thus requiring the user to tear back the tab closure from the cover when initially opening the reclosable lid. Tear guides of some sort are normally formed on the lid to aid the user in tearing back the tab closure. After the tab closure is torn along the tear guides a discontinuity remains between the lid and the tab closure at the tear guides even when the tab closure is closed. The beverage can seep out through the discontinuity as the beverage is sloshed while the container is moved by the user, resulting in a suitable but imperfect seal. 
   Therefore, there is a desire to have a disposable, reclosable lid with the cost and production benefits of the thermoforming process while providing a better seal between the tab closure and the lid than is currently obtainable with thermoformed lids having an integral tab closure. 
   SUMMARY OF THE INVENTION 
   The invention addresses the disadvantages of the prior art by providing a method and apparatus for assembling a first thermoformed workpiece, such as a tab closure, to a second thermoformed workpiece, such as a lid, without the need to temporarily store either workpiece. In the context of a tab and lid operation, the apparatus and method for assembling the tab closure to the lid are automated and integrated into the traditional thermoforming lid manufacturing process thereby maintaining the cost benefit and production volume attributable to thermoformed lids. 
   In one aspect, the invention relates to an automated manufacturing line for making a composite thermoformed article from first and second thermoformed workpieces by automatically assembling the first thermoformed workpiece to the second thermoformed workpiece. The automated manufacturing line comprises a thermoforming station for thermoforming the first and second thermoformed workpieces in a plastic sheet, a trim station for trimming at least the first thermoformed workpiece from the plastic sheet; and an assembly station for assembling the first thermoformed workpiece onto the second thermoformed workpiece to form the composite article. 
   The assembly station can assemble the first thermoformed workpiece to the second thermoformed workpiece in a number of methods, including: press-fitting, snap-fitting, bonding, or ultrasonically welding. 
   The assembly station can comprise a carrier that moves between a first position, where it picks the first thermoformed workpiece, and a second position, where it assembles the first thermoformed workpiece to the second thermoformed workpiece. A suction device can be added to the carrier to pick the first thermoformed workpiece as it is trimmed from the sheet and hold the first thermoformed workpiece as it is carried to the second thermoformed workpiece. Additionally, a force reliever can be added to the carrier to control the amount of force applied by the carrier to the first and second thermoformed workpieces as they are assembled. 
   The carrier can comprise a reciprocating arm on an end of which the suction device is mounted. The force reliever can be used to mount the suction device to the end of the arm. The reciprocating arm reciprocates between a pick-up position that corresponds to the first position, and an assembly position that corresponds to the second position. The direction of reciprocation is preferably either parallel or transverse to the machine direction as defined by the movement of the plastic sheet through the assembly station. 
   Multiple carriers, whether in the form of reciprocating arms or not, can be arranged in at least two sets, wherein when one of the at least two sets is in the first position, the other of the at least two sets is in the second position providing for the contemporaneous pick-up of a first thermoformed workpiece while a previously picked-up first thermoformed workpiece is being assembled to the second thermoformed workpiece. 
   The trim station can comprise a first punch and die set for trimming the first thermoformed workpiece from the plastic sheet. In this configuration, the die comprises an inlet opening in which the punch is received to trim the first thermoformed workpiece from the plastic sheet when the plastic sheet is positioned between the punch and die, and an outlet opening into which the reciprocating arm extends to pick up the first thermoformed workpiece when the reciprocating arm is in the pick-up position. 
   A moveable platform can be provided for carrying the reciprocating arm and which is moveable between a first position where the reciprocating arm is positioned within the die outlet, and a second position where the reciprocating arm is positioned outside of the die outlet. 
   In another aspect, the invention relates to an apparatus for automatically forming a composite article by assembling first and second workpieces thermoformed in a common plastic sheet comprising a plurality of the first and second work pieces, where the assembly station comprises: a trimmer for trimming at least one of the first workpieces from the plastic sheet; and a carrier moveable between a first position, where the carrier picks up one of the first workpieces, and a second position, where the carrier assembles the first workpiece to one of the second workpieces in the plastic sheet. 
   The carrier preferably moves directly between the first and second positions, eliminating the need to temporarily store the first workpiece prior to assembly to the one of the second workpieces. The carrier preferably assembles the first workpiece to the one of the second workpieces by press-fitting the first and second thermoformed work pieces. 
   The invention also relates to a method for automatically assembling a first thermoformed workpiece to a second thermoformed workpiece from a plastic sheet comprising a plurality of the first thermoformed workpieces and a plurality of the second thermoformed workpieces to form a composite thermoformed article. The method comprises: trimming at least one of the first thermoformed workpieces from the plastic sheet to form at least one trimmed first thermoformed workpiece; immediately after trimming, carrying the trimmed first thermoformed workpiece to a corresponding second thermoformed workpiece; and assembling the trimmed first thermoformed workpiece to the corresponding second thermoformed workpiece to form a composite thermoformed article. 
   The assembling of the trimmed first thermoformed workpiece to the corresponding second thermoformed workpiece can comprise one of press-fitting, snap-fitting, bonding, or ultrasonically welding. 
   The carrying of the trimmed first thermoformed workpiece can comprise picking up the trimmed thermoformed workpiece by suction. The carrying of the trimmed first thermoformed workpiece further can also comprise stopping the suction or overpowering the suction with pressure, at the completion of the assembly of the trimmed first thermoformed workpiece to the corresponding second thermoformed workpiece. The method can additionally comprise limiting the force applied to the trimmed first thermoformed workpiece and the corresponding second thermoformed workpiece as the trimmed first thermoformed workpiece is assembled to the corresponding second thermoformed workpiece. 
   The trimming step can comprise the trimming of multiple first thermoformed workpieces to form multiple trimmed first thermoformed workpieces, and the assembling step can comprise assembling each of the multiple first thermoformed workpieces to a corresponding second thermoformed workpiece to form multiple composite thermoformed articles. 
   The trimming can be done by trimming multiple first thermoformed workpieces. The trimming of multiple first thermoformed workpieces can comprise trimming a subset of the total number of first thermoformed workpieces from the plastic sheet. The first thermoformed workpieces forming the subset can be trimmed simultaneously from the plastic sheet. Similarly, the first thermoformed workpieces forming the subset can be simultaneously assembled to corresponding second thermoformed workpieces. 
   The method can further comprise thermoforming the first and second thermoformed workpieces in a repeating pattern of a predetermined unit. Preferably, the subset is an integer multiple of the predetermined unit. The predetermined unit is one of a row or a column. 
   The first and second workpieces can be arranged in alternating rows or columns on the plastic sheet. In such a configuration, a preferred sequence of assembly comprises the first thermoformed workpiece being trimmed from one of the alternating rows or columns and assembled onto the second thermoformed workpieces in the adjacent row or column. 
   The thermoforming can also include the first workpiece being a thermoformed closure tab having first and second projections connected by a flexible strap, the second workpiece being a thermoformed lid having a body recess and a drink opening, wherein the snap-fitting comprises inserting the first projection into the body recess and inserting the second projection into the drink opening. 
   However the first thermoformed workpieces are assembled to the second thermoformed workpieces, one additional step can include the trimming of the composite thermoformed articles from the plastic sheet. 
   In a variation, the method for automatically assembling a first thermoformed workpiece to a second thermoformed workpiece from a plastic sheet comprising a plurality of the first thermoformed workpieces and a plurality of the second thermoformed workpieces to form a composite thermoformed article, comprising: trimming at least one of the first thermoformed workpieces from the plastic sheet to form at least one trimmed first thermoformed workpiece; carrying the trimmed first thermoformed workpiece to a corresponding second thermoformed workpiece; and press-fitting the trimmed first thermoformed workpiece to the corresponding second thermoformed workpiece to form a composite thermoformed article. 
   The method can also comprise the thermoforming of the first and second thermoformed workpieces in the plastic sheet such that one of the first and second workpieces has a projection and the other has a recess, and the press-fitting comprising inserting the projection into the recess. With this configuration, the press-fitting can comprise snap-fitting the projection into the recess. The projection has a portion of greater size than a portion of the recess to effect the snap fit. The first and second thermoformed workpieces can have multiple corresponding pairs of projections and recesses. The method can further comprise thermoforming the sheet from a web of plastic. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a schematic illustration of a first embodiment of a manufacturing line for thermoforming and assembling lids in accordance with the invention and which comprises a thermoforming station, an opening forming station, an assembly station, and a trimming station. 
       FIG. 2  is a plan view of a portion of a web of thermoformed material containing lids and corresponding tab closures suitable for use in the first embodiment. 
       FIG. 3  is a top perspective view of a suitable lid and tab for use in the invention after they have been removed from the web. 
       FIG. 4  is a bottom view of the lid and tab of  FIG. 3 . 
       FIG. 5  is a top view of a forming tool for the first embodiment and which is used in the thermoforming station to form the lid and tab closure in the web. 
       FIG. 6  is a partial perspective view of the forming tool for the lid and tab closure as is shown in  FIG. 5 . 
       FIG. 7  is a front view of a punch tool assembly for the assembly station of the first embodiment and which is used to punch the tab closure from the thermoformed web and to support the lid as the tab closure is assembled thereto. 
       FIG. 8  is a partial perspective view of the punch tool assembly used in the first embodiment and illustrating a punch for punching the tab closure from the thermoformed sheet and a support element for supporting the lid on the thermoformed sheet when the tab is assembled thereto. 
       FIG. 9  is a front view of a die assembly for the assembly station of the first embodiment that cooperates with the punch tool assembly of  FIGS. 7 and 8  for punching the tab closure from the thermoformed sheet and comprises a row of access openings corresponding to the row of support elements and a row of die openings corresponding to the row of punches. 
       FIG. 10  is a sectional view taken along line  10 - 10  of  FIG. 9  and illustrating a cross section of the access opening and the die opening. 
       FIG. 11  is a partial perspective view of a tab assembly mechanism for the first embodiment including multiple tab assembly devices, each having reciprocating arms for carrying the tab closure from the web into alignment with the lid. 
       FIG. 12  is a side view of one of the tab assembly devices of  FIG. 11  and illustrating the reciprocating arms, each having tab receiver assemblies connected to each end thereof by a force relief device and for selecting a punched tab closure from the thermoformed sheet and assembling the punched tab to the lid. 
       FIG. 13  is a top-front perspective view of one of the reciprocating arms and illustrating in greater detail the connection of the tab receiver assemblies to the arm by the force relief device. 
       FIG. 14  is a top-rear perspective view of the reciprocating arm of  FIG. 13 . 
       FIG. 15  is a partially sectioned, enlarged perspective view of the tab receiver assemblies and the force relief device of  FIGS. 13 and 14 . 
       FIG. 16  is a schematic illustrating one possible control scheme for controlling the timing and indexing for the various components of the lid manufacturing line. 
       FIG. 17  is a partial sectional view of the first embodiment assembly station wherein the punch tool assembly is nearing a back stroke limit, the lower arm is prepared for picking up a tab closure, and the upper arm is carrying a tab for assembly to the lid. 
       FIG. 18  is a partial sectional view identical to  FIG. 17  except the tab assembly device is now advanced to an over-stroke position for cleaning out any tab closures that may not have been picked up during the last cycle. 
       FIG. 19  is a partial sectional view identical to  FIGS. 17 and 18  except that the punch tool assembly is shown in a forward stroke limit position where the punch has trimmed a tab closure from the web, and the tab assembly device is shown in an assembly position where the upper arm mounts a tab closure to a lid and the lower arm picks up the trimmed tab closure. 
       FIG. 20  is an alternative configuration of the manufacturing line shown in  FIG. 1 , with the opening forming station, the assembly station, and the trimming station all combined into a single station. 
       FIG. 21  is a plan view of a portion of a web of thermoformed material containing lids and the corresponding tab closures suitable for use in a second embodiment of the invention. 
       FIG. 22  is a partial front view of the punch tool assembly for the second embodiment having a tab punch used to punch the tab closure from the thermoformed web, a lid support assembly to support the lid as the tab closure is assembled thereto, and a lid punch assembly for punching an assembled lid and tab from the thermoformed sheet. 
       FIG. 23  is a partial perspective view of the punch tool assembly of  FIG. 22 . 
       FIG. 24  is a front view of a die shoe for the second embodiment that cooperates with the punch tool assembly of  FIGS. 22 and 23  for punching the closure tab and assembled lid from the thermoformed sheet and comprising a first row of alternating access openings corresponding to the row of lid support assemblies and die openings corresponding to the row of tab punches, and a second row of die openings corresponding to the row of lid punch assemblies. 
       FIG. 25  is a sectional view taken along line  25 - 25  of  FIG. 24  and illustrating a cross section of the die openings. 
       FIG. 26  is a partial perspective view of the tab assembly mechanism for the second embodiment including multiple tab assembly devices, each having reciprocating arms for laterally carrying a tab closure from the web into alignment with a lid. 
       FIG. 27  is an exploded view of one of the tab assembly devices of  FIG. 26  showing the reciprocating receiver arms and a drive assembly for moving the arms between the tab die openings and the access openings. 
       FIG. 28  is a front elevational view of one of the tab assembly devices of  FIG. 26  showing the relative operable positions of the reciprocating arms. 
       FIG. 29  is a partial sectional view of the second embodiment assembly station shown when the punch tool assembly is nearing a back stroke limit and the tab assembly device is in a back stroke limit. 
       FIG. 29A  is a partial sectional view illustrating the relative positions of the punch tool assembly, web, die shoe, and tab assembly device when viewed from above the section shown in  FIG. 29 . 
       FIG. 30  is a partial sectional view identical to  FIG. 29  except the tab assembly device is now advanced to an over-stroke position for cleaning out any tab closures that may not have been picked up during the last cycle. 
       FIG. 30A  is a partial sectional view illustrating the relative positions of the punch tool assembly, web, die shoe, and tab assembly device when viewed from above the section shown in  FIG. 30 . 
       FIG. 31  is a partial sectional view identical to  FIGS. 29 and 30  except that the punch tool assembly is shown in a forward-stroke limit position where the tab closure punch has trimmed a tab closure from the web, the tab assembly device is shown in an assembly position where a first reciprocating arm mounts a tab closure to a lid and a second reciprocating arm picks up the trimmed tab closure, and the lid punch has trimmed the assembled lid from the web. 
       FIG. 31A  is a partial sectional view illustrating the relative positions of the punch tool assembly, web, die shoe, and tab assembly device when viewed from above the section shown in  FIG. 30 . 
       FIG. 32  is a perspective view of an alternative lid support assembly having a reduced area to ease the removal of the lid while still supporting the lid during the assembly of the tab closure. 
   

   DETAILED DESCRIPTION 
     FIG. 1  schematically represents a first embodiment automated lid manufacturing line  10  according to the invention. The lid manufacturing line  10  comprises a thermoforming station  12 , an opening forming station  14 , an assembly station  16 , and a lid trimming station  18  through which a plastic web  20  passes. An overview of the general operation of the lid manufacturing line  10  will be useful in understanding the details of the invention. The thermoforming station  12  forms a tab and lid in the plastic web  20 . As the plastic web  20  continues through the various stations of the manufacturing line  10 , openings, such as drink openings and vent openings, for example, are punched in the tab closure and lid at the opening forming station  14 . The tab is removed from the plastic web  20  and assembled to the lid at the assembly station  16 . The lid with the assembled tab is then transferred from the assembly station  16  to the lid trimming station  18 , where the assembled lid is trimmed from the web to complete the manufacture of the reclosable lid. 
     FIG. 2  illustrates an example of a portion of a suitable plastic web  20  that has passed through the thermoforming station  12  resulting in lids  30  and tab closures  32  being formed in the plastic web  20  and arranged in alternating and aligned rows comprising five lids and five tab closures. The web is preferably made from a suitable plastic, an example of which is HIPS. 
   An illustrative lid  30  and tab closure  32  are shown in greater detail in  FIGS. 3 and 4 . The lid  30  comprises a cup mounting ring  34  from which extends a peripheral wall  36 , which terminates in an upper surface  38  in which is formed a drink opening recess  41  in the form of a punched-out hole in the bottom of a recessed well. The upper surface  38  of the peripheral wall  36  transitions into a top surface  40 , which is generally parallel to the mounting ring  34 . A D-shaped well forming a reservoir  42  is formed in the top surface  40  along with a channel  44 . A locking recess  46  extends from the top surface  40  and into the peripheral wall  36 , where it terminates in opposing inwardly extending fingers  48 . 
   The tab closure  32  comprises a mounting portion  49  including a D-shaped mounting plug  50  and a tab portion  51  including a sealing plug  52 . A hinge in the form of a channel  54  is formed adjacent the mounting plug  50  and permits the sealing plug  52  to be pivoted relative to the mounting plug  50 . The mounting plug  50  is preferably sized to be pressed into the reservoir  42  of the lid  30 . Similarly, the sealing plug  52  is sized to be pressed into the drink opening recess  41 . 
   The affixing of the mounting plug  50  and the sealing plug  52  is preferably accomplished by providing the mounting plug  50 , sealing plug  52 , reservoir  42 , and drink opening recess  41  with a slight draft or taper to their sidewalls. The reservoir  42  and drink opening recess  41  preferably have a negative draft such that the sidewall extends back under the top surface  40  and upper surface  38 , respectively. The mounting plug  50  and sealing plug  52  also have a negative draft. It is also preferred that the lower peripheral edge of the mounting plug  50  and sealing plug  52  have a slightly greater periphery than the upper edges of the reservoir  42  and the drink opening recess  41 , which in combination with the negative draft, permit the mounting plug  50  and sealing plug  52  to be pressed into the reservoir  42  and drink opening recess  41  to mount the tab closure  32  to the top surface  40  of the lid  30  by snap-fitting a portion of the tab closure  32  into the lid  30 . 
   It should be noted that for purposes of this application the term “press-fit” refers to any type of connection where two parts are connected by at least a portion of one of the parts being received within the other and the resulting interaction between the parts, whether it be frictional, mechanical or another coupling type, results in their coupling, whether it be permanent or temporary. The term “snap-fit” is used to denote a subset of press-fit where there is at least a mechanical coupling. 
   When the tab closure  32  is mounted to the lid  30 , the drink opening recess  41  is selectively opened and closed by the user selectively pulling or pressing on the tab portion  51  to unsnap or snap-fit the sealing plug  52  within the drink opening recess  41 . If it is desirable to fix the tab closure  32  in an opened position, the user merely needs to pivot the tab portion  51  about the hinge  54  into the locking recess  46  until the edges of the tab portion  51  pass by the locking fingers  48 . The inherent resiliency of the tab closure  32  permits the side edges of the tab portion  51  to deflect beneath the locking fingers  48 , which will hold the tab portion  51  in the opened position until unlatched by the user. 
   It is important to note that the lid  30  and tab closure  32  illustrated in the patent application are only one of any type of lid and tab closure structures that can be assembled according to the invention. The lid  30  and tab closure  32  are therefore merely illustrative and aid in explaining the invention and are not in any manner limiting to the invention. 
   While the connecting of the tab closure  32  to the lid  30  is described as pressing a portion of the tab closure  32  into a portion of the lid  30 , the lid  30  could just as easily be pressed onto the tab closure  32 . As a matter of convenience and simplicity, the connection of the tab closure  32  to the lid  30  is described herein as the tab closure  32  being pressed into the lid  30 , with it being understood the description just as easily applies to the pressing of the lid  30  onto the tab closure  32 . 
   It should also be noted that the illustrative lid  30  and tab closure  32  are shaped to result in a snap-fit connection. However, the invention is not limited to such a snap-fit connection. Any suitable connection can be used with the invention, for example: press-fit, friction-fit, ultrasonic welding, or adhesion. 
   The invention is also not limited to assembling tabs to lids. The invention is equally applicable to the assembly of other components and is most suitable for assembling an article comprising multiple pieces formed in a web, at least one of which is removed from the web and assembled to one of the other pieces. 
     FIG. 5  illustrates a top view of the thermoforming station  12  and multiple lid and tab closure forms  62 ,  64  about which the web  20  is shaped to form the lids  30  and tab closures  32 . The forms  62 ,  64  are arranged in the same alternating rows as the web  20  of  FIG. 2 . To form the lids  30  and tab closures  32  in the web  20 , the web  20  is heated and laid on top of the forms  62 ,  64 . A vacuum is applied to the lower surface of the web  20  to draw the web  20  against the forms  62 ,  64 , while pressurized air is then imparted to the top of the web  20  to force the web  20  to take the shape of the forms  62 ,  64 . Subsequently, the web  20  is lifted up off the forms  62 ,  64  and advanced. 
   The structure and operation of the thermoforming station  12  are generally well known in the art and further description is not necessary. An example of a suitable forming station is an IRAD Model 44 sold by Irwin Research and Development, Yakima, Wash. 
   It should be noted that the number of forms per row is not limiting on the invention. For purposes of this description five forms are shown for each row. However, any desired number of forms can be used for each row. 
   Referring now to  FIG. 6 , a corresponding pair of lid and tab closure forms  62 ,  64  are shown in greater detail. The forms  62 ,  64  conform to the shape of the lid  30  and tab closure  32  as previously described. Therefore, they will only be briefly described. 
   The lid form  62  comprises multiple surfaces against which the web  20  is formed. The surfaces include a mounting ring surface  74 , a peripheral wall surface  76 , a lid form upper surface  78 , a top surface  80 , a drink opening surface  81 , a reservoir surface  82 , a channel surface  84 , and a locking recess surface  86 . Similarly, the tab closure form  64  comprises a raised upper surface  88  in which is formed a mounting plug surface  90 , a sealing plug surface  92 , and a hinge surface  94 . The sealing plug surface  92  is formed in a raised portion  93  whose upper surface will form the tab portion  51 . Similarly, the raised upper surface  88  will form the mounting portion  49  once the tab closure  32  is trimmed from the web  20 . 
   Once the lids  30  and tab closures  32  are formed in the web  20 , the web  20  is ultimately advanced to the opening forming station  14  where the drink and vent openings are created in the lids  30  and tab closures  32 . The opening forming station  14  is well known to one of ordinary skill in the art and will not be described in detail. For purposes of the invention, it is only necessary to understand that the opening forming station  14  removes the material in the drink opening recess  41  to form a drink opening therethrough. Similarly, the opening forming station  14  also creates a vent opening in the bottom of the reservoir  42  and another vent opening in the bottom of the mounting plug  50  to create a vent opening extending through the lid  30  and the tab closure  32  when the tab closure  32  is mounted to the lid  30 . 
   A suitable opening forming station  14  is an IRAD Model 44 sold by Irwin Research and Development, Yakima, Wash., and uses a punch and die structure to create the openings. It is also within the scope of the invention for the openings to be formed by the thermoforming station  12 . 
     FIGS. 7-13  illustrate the details of the assembly station  16  where the tab closures  32  are removed from the web  20  and snap-fitted to the lids  30 . Beginning with  FIG. 7 , the assembly station  16  comprises an assembly to trim the tab closures  32  from the web  20 . The trim assembly is in the form of a punch tool assembly  100  from which extends a row of tab punch assemblies  102  for separating the tab closures  32  from the web  20  and a row of lid support assemblies  104  for supporting the lid  30  when the tab closure  32  is mounted to the lid  30 . 
   Referring to  FIGS. 7 and 8 , each tab punch assembly  102  comprises a base  106  on which is mounted a tab punch  108 . The tab punch  108  has a punch upper surface  110  that conforms to and corresponds to the surface of the tab closure  32  that faces the lid  30 . The punch upper surface  110  includes a mounting portion surface  112  and a tab portion surface  114  on which are supported the mounting portion  49  and the tab portion  51 , respectively. A mounting plug recess  116 , a sealing plug recess  118 , and a hinge recess  120  are formed in the punch upper surface  110  and are sized and located to receive the mounting plug  50 , sealing plug  52 , and hinge  54 , respectively, when the punch  108  contacts the web  20  to assure that the mounting plug  50 , sealing plug  52 , and hinge  54  are not deformed by the punching process. 
   The lid support assemblies  104  comprise a base  126  on which is mounted a support element  128  having an exterior surface  130  that generally conforms to the inner surface of the lid  30 . The exterior surface  130  comprises a peripheral wall support  132 , an upper surface support  134 , a top surface support  136 , a reservoir support  138 , and a drink opening support  140 . With this structure, the peripheral wall  36 , the upper surface  38 , and the top surface  40  of the lid  30  are supported along with the reservoir  42  and the drink opening  41  while the mounting plug  50  and sealing plug  52  are snap-fitted within the reservoir  42  and drink opening  41 , respectively. 
     FIG. 9  illustrates a die assembly  150  that cooperates with the punch tool assembly  100  to trim the tab closures  32  from the web  20  while permitting subsequent mounting of the trimmed tab closures  32  to the lids  30 . The die assembly  150  comprises a die shoe  152  in which are formed two rows of access openings  154 . The number of access openings  154  in each row corresponds to the number of lids  30  and tab closures  32  in the web  20 . A tab die  156  is mounted to the die shoe  152  at each of the openings  154  of the lower row. Each tab die  156  includes a die opening  158  that is sized to receive the tab punch  108  and which is partially surrounded by a support element  160 , which functions similar to the support element  128  of the punch tool assembly  100  in that the support element  160  supports the portion of the web  20  surrounding the area from which the tab closure  32  is to be punched. 
   Although the preferred form of the invention is described in the context of punching one tab closure  32  while affixing an already punched tab closure  32  to a lid  30 , additional punch tool assemblies  100 , die assemblies  150 , and tab assembly mechanisms  190 , which will be discussed in detail hereinafter, can be added to provide for the simultaneous punching and assembly of multiple tab closures  32  to multiple lids  30 . For example, additional punch tool assemblies  100 , die assemblies  150 , and tab assembly mechanisms  190  could be added to permit the simultaneous punching and assembly of tab closures  32  for a portion of the web  20  that corresponds to the number of rows of tab closures  32  and lids  30  formed by the thermoforming station  12  in a single forming operation. With such a configuration, the web  20  would be advanced or indexed in sequence with the thermoforming station  12 . 
   Referring to  FIG. 10 , the interior shape of the access opening  154  and the die opening  158  are shown. Initially, the die opening  158  has a reduced height as it extends through the support element  160 . When the die opening  158  reaches the main portion of the tab die  156 , there is a slight increase in the height of the die opening. The die opening  158  then opens into the lower access opening  154  extending through the die shoe  152 . 
   The punch tool assembly  100  is mounted for relative movement to the die assembly  150 . When the web  20  is disposed between the punch tool assembly  100  and the die assembly  150 , the punches  102  and support elements  104  are aligned to be received within the die opening  158  and the upper row of access openings  154 , respectively. Upon movement of the punch tool assembly  100  toward the die assembly  150 , the tab punch  108  is received within the die opening  158  to trim the tab closures  32  from the web  20  and the support elements  128  support the back of the lid  30  for assembly of a tab closure  32  onto the lid  30 . 
   The particular manner in which the punch tool assembly  100  is moved relative to the die assembly  150  is not germane to the invention and will not be described in detail. One of ordinary skill in the art will understand that there are many ways in which the movement of the punch tool assembly  100  can be accomplished. 
     FIG. 11  illustrates the tab assembly mechanism  190  that functions as a carrier to pick up the punched tab closure  32  and assemble it to the lid  30 . The tab assembly mechanism  190  comprises multiple tab assembly devices  192 . Although FIG.  11  only illustrates three tab assembly devices  192 , a tab assembly device  192  is provided for each column of alternating lids  30  and tab closures  32  on the web  20 . Thus, for the web  20 , as illustrated, five tab assembly devices  192  would be used. 
   Referring to  FIGS. 11 and 12 , each tab assembly device  192  comprises a central beam  196  that is fixedly mounted to a base  198 , which is movably mounted on parallel rails  200  for permitting the tab assembly devices  192  to reciprocate relative to the die assembly  150 . A pair of receiver arms  204  are connected to common shafts  206 , which are journaled in the central beam  196 , by crank arms  208 . One end of the crank arms  208  is fixedly mounted to the shafts  206  and the other end of the crank arms  208  is pivotally mounted to the receiver arms  204 . 
   A spur gear  210  is mounted to one of the shafts  206  and is used instead of a crank arm  208  to connect one end of one of the receiver arms  204  to the shaft  206 . The spur gear  210  is meshed with a drive gear  212  that is mounted to a drive shaft  214  journaled in the end of the central beam  196 . 
   Rotation of the drive shaft  214  thereby simultaneously rotates the drive gears  212  for all of the tab assembly devices  192  and results in the simultaneous rotation of the spur gears  210  to effect the reciprocal movement of the receiver arms  204 . Since the receiver arms  204  are connected to the central beam  196  by crank arms  208 , the rotation of the spur gear  210  effectively reciprocates the receiver arms  204  between a lower position that is aligned with the die openings  158  and an upper position that is aligned with the upper row of access openings  154 . It is preferred that a servomotor  216  (shown in phantom in  FIG. 11 ) is connected to the drive shaft  214  to reciprocally rotate the drive shaft  214  to effect the reciprocation of the receiver arms  204  between the lower and upper positions. 
   Referring to  FIGS. 13-15  specifically, and  FIGS. 11 and 12  generally, a tab receiver  220  is mounted at the very tip of the receiver arm  204  by a force reliever  260 , which permits the tab receiver  220  to move relative to the receiver arm  204  if the tab receiver  220  is impacted by a large enough force. Each tab receiver  220  comprises a main body  222  having a lower surface  224  in which is provided a fluid port  240  to which an air line  254  ( FIG. 16 ) is connected. The body  222  also has an upper surface  226  that conforms to the upper surface of the tab closure  32 . The upper surface  226  comprises a tab portion  228  that corresponds to the tab portion  51  of the tab closure  32  and a mounting plug portion  230  that corresponds to the mounting portion  49  of the tab closure  32 . 
   A tab suction inlet  232  is located in the tab portion  228  and is shaped to be received within the sealing plug  52  of the tab closure  32 . Similarly, a mounting plug suction inlet  234  is located in the mounting portion  230  and is shaped to be received within the mounting plug  50  of the tab closure  32 . Each suction inlet  232  and mounting plug inlet  234  comprise air passages  236 ,  238 , respectively, which are piped to the suction port  240  to thereby fluidly couple the air line  254  to the suction inlets  232 ,  234  for drawing a suction against the mounting plug  50  and sealing plug  52  when the sealing plug  52  and mounting plug  50  are picked up to hold the tab closure  32  against the tab receiver  220 . Additionally, air can be injected into the air line  254  and exhausted through the suction ports  232 ,  234 . 
   The force reliever  260  comprises a platform  261  that is fixedly connected to the receiver arm  204  by screws  262  extending through the arm and into a side edge of the platform  261 . The platform  261  comprises spaced guide pin openings  264 , between which is provided an air line passage  266  through which the air line  254  passes when it is mounted to the suction port  240 . The guide pin openings  264  comprise a frustoconical countersink portion  268  and a constant diameter portion  270 . 
   Mounting pins  272  comprising a frustoconical mounting pin head  274  and a constant diameter shaft  276  are sized to be received within the guide pin openings  264 , such that the guide mounting pin heads  274  nest with the countersink portion  268  of the guide pin opening  264  and the ends of the mounting pin shaft  276  extend through the constant diameter portion  270  of the guide pin opening  264  and contact the tab receiver  220 . A coil spring  278  is mounted over each shaft  276  and extends between the tab receiver  220  and the platform  261 , such that one end of the spring abuts the lower surface  224  of the tab receiver and the other end abuts the platform  261 . A screw  280  is received through the mounting pins  272  and threaded into the tab receiver  220  to fix the mounting pins  272  to the tab receiver  220 . 
   The function of the force reliever  260  is to relieve any force imparted to the tab receiver  220  by contact with the tab punch  108  during the punching of the tab closure  32  from the web  20  and the picking up of the punched tab closure  32  by the tab receiver  220 . If contact occurs between the tab punch  108  and the tab receiver  220 , the springs  278  will compress, and the tab receiver  220  will slide toward the platform  261 , thus resulting in the corresponding movement of the shafts  276  within the guide pin openings  264  to relieve the force and prevent damage to the tab receiver  220  and other components of the tab assembly mechanism  190 . As the shafts  276  slide relative to the platform  261 , the mounting pin heads  274  are unseated from the countersink portion  268  of the guide pin openings  264 . 
   Upon the relative separation between the tab receiver  220  and the tab punch  108 , the springs  278  bias the tab receiver  220  away from the platform  261  and return the mounting pins  272  to their prior position. Upon their return, the mounting pin heads  274  nest within the countersink portion  268 , which functions to center and align the mounting pins  272  relative to the guide pin openings  264 . Additionally, the counter sink portion  268  reduces the likelihood that the shaft  276  will bind as it slides within the constant diameter portion  270 . 
     FIG. 16  is a schematic representation of one possible method for controlling and synchronizing the various operations of the punch tool assembly  100  and tab assembly mechanism  190  (not shown in  FIG. 16 ), with the rest of the lid manufacturing line  10 . It is preferred that two controllers, a tab assembly controller  250  and a tab punch tool controller  251 , are provided to operably control the operation and synchronization of the tab assembly mechanism  190  and the punch tool assembly  100 , respectively. The tab assembly controller  250  and tab punch tool controller  251  are connected by a data link  253 , which permits the transfer of data, such as timing or position data, as need be between the controllers  250 ,  251 . 
   The tab assembly controller  250  is operably connected to a vacuum source  252  that is connected by air lines  254  to the suction port  240  of each of the tab receivers  220  on the end of the arms  204 . The air lines  254  preferably comprise a fitting portion that connects to the tab receiver  220  and a flexible hose portion that connects the fitting portion to the vacuum source  252 . The tab assembly controller  250  also connects the air lines  254  to a compressed air supply  255 . 
   Thus, the tab assembly controller  250  is able to control the application of the vacuum or pressurized air to the tab receivers  220  to hold the tab closures  32  after they are trimmed from the web  20  or to blow out any tab closure  32  left in the die assembly  150 . The tab assembly controller  250  is also operably coupled to a base actuator  256  for reciprocating the base  198  of the tab assembly mechanism  190  relative to the die shoe  152  of the die assembly  150 . The tab assembly controller  250  is further connected to the servomotor  216  to effect the reciprocation of the drive shaft  214  and thereby reciprocate the receiver arms  204  between the lower and upper positions. Thus, the tab assembly controller  250  controls the operation of the various components of the tab assembly mechanism  190  to effect the picking up of a punched tab closure  32 , moving the picked up tab closure  32  into alignment with a lid  30 , and mounting the tab closure  32  to the lid  30 . 
   The tab punch tool controller  251  is operably coupled to an actuator  258  to reciprocate the punch tool assembly  100  relative to the die shoe  152  of the die assembly  150 . The tab punch tool controller  251  also controls the indexing and advancement of the web  20  through the assembly station  16 . Thus, the tab punch tool controller  251  controls the advancement of the web  20  to an indexed position where the punch tool assembly  100  is advanced to punch the tab closure  32  from the web  20 , where it can then be picked up by the tab assembly mechanism  190 . 
   The type of actuator  256 ,  258  can be any suitable actuator, such as, for example, hydraulic cylinders, pneumatic cylinders, mechanical drives, and electrical motors. Also, it is within the scope of the invention for the tab assembly mechanism  190  to be mechanically operated, instead of using the servo  216 , actuator  256 , and even controller  250 . Under such an implementation, suitable mechanical connections or linkages can couple the tab assembly mechanism  190  to the punch tool assembly  100 , wherein the movement of the punch tool assembly  100  generates the desired synchronized movement of the tab assembly mechanism  190 , including both the reciprocation of the base  198  and the arms  204 . The vacuum source  252  could be operated by the tab punch tool controller  251  or directly by a position sensor, such as a limit switch. 
   It is also within the scope of the invention for the multiple controllers  250 ,  251  to be replaced by a single controller that controls the operation and timing of the various elements of the tab assembly station  10  as need be relative to the plastic web  20  to effect the punching of the tab closure  32  from the plastic web  20 , the pickup of the punched tab  32 , and the assembly of the punched tab  32  to the lid  30 . 
   Referring to  FIGS. 16-19 , the operation of the assembly station  16  is generally described. For purposes of the description, it is presumed that the operation is begun when the punch tool assembly  100  is near its back stroke, the upper and lower receiver arms are in the upper and lower positions, respectively, lower receiver arm  204  is not carrying a tab closure  32 , and upper receiver arm  204  is currently carrying a tab closure  32  that was picked up in the prior cycle. From this position, the tab punch tool controller  251  continues the steady-state reciprocation of the punch tool assembly  100  and advances the plastic web  20  to index the next rows of lids  30  and tab closures  32  into alignment with the access openings  154 . The tab assembly controller  250  then initiates the base actuator  256  to advance the tab assembly mechanism  190  toward the die assembly  150 . The rate of advancement of the tab assembly mechanism  190  is greater than the substantially constant stroke rate of the punch tool assembly  100 , which is beginning to move forward from its back stroke position toward the die assembly  150 . 
   Referring to  FIG. 18 , the faster speed of the base  198  as it moves on the rails  200  results in the tab receivers  220  extending into and through the die opening  158  beyond the support element  160  into a position that is referred to as an over-stroke position. At this point in the cycle, the tab assembly controller  250  turns on the vacuum source  252 . The purpose of the over-stroke position is to ensure that no tab closures  32  were left in the die opening  158  from the prior cycles. If desired, the tab assembly controller  250  can cause a burst of pressurized air to be exhausted from the tab suction inlet  232  and mounting plug inlet  234  to blow out any tab closures  32 . 
   The tab assembly controller  250  then reverses the direction of movement for the base  198  of the tab assembly mechanism  190  to withdraw the tab receivers  220  from the die opening  158  into a standby position. In the standby position, the base  198  of the tab assembly mechanism  190  is preferably stopped on the rails  200  at a position where the tab receivers  220  are located at the furthest insertion depth reached by the tab punch assembly  102  to permit abutting contact between the tab receiver  220  and the tab punch  108  to improve the likelihood of a successful pickup of the tab closure  32  by the tab receiver  220 . If, for any reason, the tab receivers  220  are located beyond the forward stroke limit of the tab punch  108 , the force reliever  260  will permit the tab receiver  220  to move in response to contact with the tab punch  108  without damage while still permitting the tab receiver  220  to pick up the tab closure  32 . 
   Referring to  FIG. 19 , with the tab receivers  220  in the standby position, the controller  251  continues the steady advance of the punch tool assembly  100  until the punch tool assembly  100  reaches its forward stroke limit. As the punch tool assembly  100  moves towards the forward stroke limit, the lid support  104  is received within the lid  30 , which by now is aligned relative to the upper access opening  154 . Similarly, the tab punch assembly  102  initiates contact with the web  20 . The continued advancement of the punch tool assembly  100  to its forward stroke limit results in the tab punch assembly  102  extending into the die opening  158  thereby trimming the tab closure  32  from the web  20  while the area surrounding the now-punched tab closure  32  is supported by the support element  160 . 
   As the punch tool assembly  100  reaches its forward stroke limit, the tab receiver  220 , with the vacuum on, is awaiting the arrival of the tab closure  32  punched from the web  20 . As the tab punch  108  reaches the forward stroke limit, the tab closure  32  is pulled by the vacuum against the tab receiver  220 . In addition to the picking up and retaining of the tab closure  32 , the advancement of the base  198  of the tab assembly mechanism  190  as the punch tool assembly  100  reaches its forward stroke limit also causes the tab receiver  220  of the receiver arm  204  in the upper position to press the tab closure  32  that it is currently carrying against the lid  30  currently supported by the lid support  104 . Since the tab receiver  220  is holding the tab closure  32  such that the mounting plug  50  and sealing plug  52  are aligned with the reservoir  42  and drink opening  41 , respectively, the pressing of the tab closure  32  against the lids  30  results in the mounting plug  50  and sealing plug  52  being snap-fit within the reservoir  42  and drink opening  41 , respectively, to mount the tab closure  32  to the lid  30 , with the tab closure  32  being in the closed position. 
   An additional benefit of the force reliever  260  is that the tab assembly pressing force can be controlled by selecting the spring force of the springs  278 . In other words, the tab receiver  220  carrying the tab closure  32  for mounting to the lid, presses the tab closure  32  against the lid  30 . The force used to press the tab closure  32  against the lid  30  can be controlled by selecting the spring force of the springs  278 . 
   Once the punch tool assembly  100  begins moving from the forward stroke limit toward the back stroke limit, the base  198  of the tab assembly mechanism  190  is moved to its back stroke position. As the base  198  is being moved to its back-stroke position, the tab assembly controller  250  initiates the actuation of the servomotor  216  to move the receiver arms  204  from their current position to their opposite position. In other words, the receiver arm  204  currently in the lower position is moved to the upper position and the receiver arm  204  currently in the upper position is moved to the lower position. To avoid any potential contact between the receiver arms  204  and the die shoe  152  of the die assembly  150 , the actuation of the servomotor  216  preferably does not occur until the tab receivers  220  are completely withdrawn from the access openings  154  in the die shoe  152 . 
   The punch tool controller  251  preferably continues the steady-state reciprocation of the punch tool assembly  100  while the tab assembly controller  250  continues the syncopated movement of the tab assembly mechanism  190 . Thus, the pickup of the tab closure  32  by the tab receiver  220  in the lower position and the snap-fitting of the tab closure  32  to the lids  30  by the tab receiver  220  in the upper position are performed on a continuous basis. This series of steps is continuously repeated as need be as long as the plastic web  20  is supplied to the assembly station  16 . 
   After the tab closures  32  are assembled to the lids  30 , the plastic web  20  is advanced to the lid trimming station  18  where the now assembled lid  30  and tab closure  32  combinations are trimmed from the plastic web  20  by a punch and die in a well-known manner, which is similar to the trimming of the tab closure  32  from the plastic web  20 . Therefore, the lid trimming station  18  will not be described in detail. A suitable trimming station  18  is an IRAD Model 44 sold by Irwin Research and Development, Yakima, Wash., and uses a punch and die structure to trim the assembled lids  30  from the web  20 . 
   In general, operation of the assembly station  16  can be thought of as a machine-direction assembly process where, as the plastic web  20  is advanced by indexing the web  20  relative to the various stations  12 - 18 , the tab closures  32  are trimmed from one row of a pair of rows comprising a row of tab closures  32  and an adjacent row of lids  30 . The trimmed tab closures  32  are mounted to the lids  30  in the next paired rows of tab closures  32  and lids  30 . In other words, the trimmed tab closures  32  are not mounted to the lids  30  in the first immediately adjacent row, but are mounted to the lids  30  in the second immediately adjacent row. 
   While this particular assembly sequence is preferred, it should not be considered limiting on the invention. Other sequences are possible. For example, the tab closures  32  could be mounted to the immediately adjacent row of lids  30  by the tab punch tool controller  251  holding the punch tool assembly  100  at the forward stroke limit while the receiver arm  204  is moved from the lower position to the upper position to mount the tab closures  32  to the lid  30 . In such a configuration, the tab assembly device  192  would only need one receiver arm  204 . The disadvantage of such an assembly is that it would run slower than the preferred embodiment. 
   Another possible variation is that many of the individual stations  12 - 18  of the manufacturing line  10  can be combined into a single station. For example,  FIG. 20  illustrates a configuration where the opening forming station  14 , the assembly station  16 , and the lid trimming station  18  are combined into a single station. Since all three of these stations  14 - 18  typically use a punch and die structure to perform the opening forming, tab closure punching, and lid trimming functions, combining them will not present any insurmountable technical hurdles. 
   An additional variation worth mentioning is that the tab assembly mechanism  190  could also incorporate an ultrasonic welder that would be used to affix the tab closure  32  to the lid  30 . In such a configuration, the tab receiver  220  could still be used to hold and position the tab closure  32  relative to the lid  30  for the ultrasonic welder. In fact, the ultrasonic welder could be incorporated into a portion of the tab receiver  220 . Similarly, the tab assembly mechanism  190  could incorporate an adhesive application for gluing the tab closure  32  to the lid  30 . 
   It is also within the scope of the invention for the tab closures  32  to be assembled to the lids  30  in a direction transverse to the machine direction. In such a configuration, the lids  30  and tab closures  32  would be arranged in columns instead of rows as illustrated in  FIG. 2 . The tab assembly devices  192  would need to be rotated approximately ninety degrees such that their movement between the lower and upper positions would now become a movement between a left and a right position. With this configuration, the tab closure  32  from one column is assembled to the lid  30  in an adjacent column. The disadvantage of this configuration as compared to the first embodiment is that fewer lids  30  can be assembled for a given web  20  width. For most lid manufacturing lines  10 , there is a practical limit on the width of the web  20 . Therefore, from a production output standpoint, it is more beneficial to assemble as many lids  30  for a given web  20  width as possible. 
   The stroke sequence and distances are also not limiting. For example, if clogging of the tab closures  32  within the die opening  158  is not an issue, then the tab receivers  220  need not be moved into the over-stroke position. Instead, they can be immediately moved to the standby position. 
     FIGS. 21-31  illustrate a second embodiment tab assembly line in accordance with the combined assembly station  16  and final trim station  18  shown in  FIG. 20  and where the tabs are laterally or horizontally assembled to the lids. Since the substantive differences between the first and second embodiments are found in the assembly station, only the new assembly station will be described in detail, with it being understood that the description of the other stations for the first embodiment are applicable to the second embodiment. 
     FIG. 21  illustrates a portion of a plastic web  320  suitable for use with the second embodiment. Lids  330  and tab closures  332  are formed in the plastic web  320  and arranged in alternating and aligned columns comprising four tab columns and four lid columns. The lids  330  are identical to the lids  30  and the tab closures  332  are identical to the tab closures  32  except that they are rotated ninety degrees and arranged into columns instead of rows, which is a function of the horizontal assembly. 
   As with the first embodiment, the plastic web  320  is preferably made from a suitable plastic, an example of which is HIPS. The lids  330  and the tab closures  332  are formed in a thermoforming station  12  having lid forms and tab closure forms identical to the lid forms  62  and the tab closure forms  64  of the first embodiment, except that the forms  62 ,  64  are organized into rows and columns in order to form the plastic web  320  shown in  FIG. 21 . 
     FIGS. 22 and 23  illustrate the details of the second embodiment assembly station wherein the tab closures  332  are removed from the plastic web  320  and mounted to the lids  330 . Referring to  FIG. 22 , the assembly station comprises a trim assembly in the form of a punch tool assembly  300  comprising an upper row formed from alternating tab punch assemblies  102  for separating the tab closures  332  from the plastic web  320 , and lid support assemblies  104  for supporting a lid  330  when the tab closure  332  is mounted to the lid  330 . The punch tool assembly  300  further comprises a lower row formed from lid punch assemblies  302  for separating a lid  330  with an assembled tab  332  from the plastic web  320 . A lid punch assembly  302  is located beneath each of the support assemblies  104 . 
   The punch assemblies  102  and lid support assemblies  104  were described in detail for the first embodiment. The only distinction between the punch assemblies  102  and the lid support assemblies  104  between the first and second embodiments is their rotational orientation and arrangement on the punch tool  300  as preferred to implement the horizontal assembly. 
   The lid punch assembly  302  is used to trim the lid  330  from the plastic web  320 . In the first embodiment, the lid punch assembly  302  would have been located on the first embodiment trimming station  18 . The lid punch assembly  302  comprises a generally columnar base  304  on which is mounted a circular lid punch  306 . The lid punch  306  comprises an annular mounting ring  308 , a neck  310  that supports an annular trim ring  312 , and a pilot  314  extending from the trim ring  312 . 
   The lid punch assemblies  302  are vertically aligned with the lid support assemblies  104 . The mounting ring  308  abuts the base  304 . The pilot  314  is shaped for insertion into the lid  330  and aligns and supports the lid  330  during the trimming process. The trim ring  312  is used to physically trim the lid  330  from the plastic web  320 . 
     FIGS. 24 and 25  illustrate a die assembly  350  that cooperates with the punch tool assembly  300  to trim the tab closures  332  from the web  320 , mounts the tab closures  332  to the lids  330 , and trims the assembled lids  330  from the plastic web  320 . The die assembly  350  comprises a die shoe  352  in which are formed a top row of access openings  154  and a bottom row of access openings  154 . The number of access openings  154  in the top row at least corresponds to the number of lids  330  and tab closures  332  in each row of the web  320 . The number of access openings  154  in the bottom row at least corresponds to the number of assembled lids  330  in each row of the plastic web  320 . 
   A tab die  156  is mounted to the die shoe  352  at alternating access openings  154  of the top row. Thus, the top row comprises a row of alternating access openings  154  without dies  156  and with dies  156 . A lid die  340  is mounted to the die shoe  352  at each of the openings  154  of the lower row, which alternates with the tab dies  156  on the top row. Each lid die  340  comprises a main body  346  from which extends a support element  344 , which supports the portion of the web  320  surrounding the area from which the assembled lid  330  is to be punched. The lid die  340  includes a die opening  342  that transitions from a first diameter to a larger second diameter at the junction of the support element  344  and body  346 . The first diameter is sized to receive the trim ring  312  of punch assembly  302 . The larger second diameter aids in removing the trimmed lid  330  from the lid die  340  since the trimmed lid  330  is less likely to get caught in the opening. 
   The punch tool assembly  300  is mounted for relative movement to the die assembly  350 . When the plastic web  320  is disposed between the punch tool assembly  300  and the die assembly  350 , the tab punch assemblies  102  and the lid support assembly  104  are aligned to be received within the die openings  158  and the access openings  154 , respectively, in the top row of the die assembly  350 , and the lid punches  306  are aligned to be received within the die openings  342  in the bottom row of the die assembly  350 . Upon movement of the punch tool assembly  300  toward the die assembly  350 , the tab punch  108  is received within the die opening  158  to trim the tab closures  332  from the plastic web  320 , the lid support assembly  104  supports the back of the lid  330  for assembly of a tab closure  332  onto the lid  330 , and the lid punch  306  is received within the die opening  342  to trim the assembled lid  330  from the plastic web  320 . 
     FIG. 26  illustrates the tab assembly mechanism  354  for the second embodiment used to pick up the separated tab closures  332  and assemble them to the horizontally adjacent lid  330 . The tab assembly mechanism  354  comprises two tab assembly devices  356 , with each tab assembly device  356  corresponding to two pairs of tab closure  332  and lid  330  columns comprising the plastic web  320 . That is, each tab assembly device  356  is designed to pick up two tabs  332  and place each of the tabs  332  on a separate lid  330  in one stroke. 
   Referring now to  FIGS. 26-28 , each tab assembly device  356  comprises a base frame  376  that is slidably mounted to rails  200  fixedly mounted in the assembly station  16  to permit the tab assembly devices  356  to reciprocate relative to the die assembly  350 . The base frame  376  is shown as a generally plate-like structure to which is fixedly mounted a servomotor  372 . 
   A pair of upper plate drive wheels in the form of timing pulleys  364 ,  365  are attached to axles  370 , which are journaled to and extend through the base frame  376 , preferably along the longitudinal axis of the base frame  376  in line with the servomotor  372 . Lower plate drive wheels in the form of a wheel  377  and a driven gear  378  are fixedly mounted to the axles  370  on the opposite side of the base  376  and secured on the axle  370  with a suitable fastener, shown in  FIG. 27  as axle locking collars  382 . The wheel  377  is mounted to the axle  370  on which the timing pulley  365  is mounted. The driven gear  378  is mounted to the axle  370  to which the timing pulley  364  is mounted. As so assembled, the upper and lower plate drive wheels  364 ,  365 ,  377 ,  378  rotate in unison with their corresponding axle  370 . 
   A toothed drive gear  380  is fixedly attached to the output shaft  373  of the servomotor  372  by a suitable connector, such as a drive gear locking collar  381 , for rotation of the drive gear  380  with rotation of the servomotor  372 . The drive gear  380  engages the lower plate driven gear  378  for rotation of the lower plate driven gear  378  in response to the actuation of the servomotor output shaft  373 . The rotation of the lower plate driven gear  378  also rotates the upper plate timing pulley  364 . A toothed belt  366  connects the upper plate timing pulleys  364 ,  365  so that rotation of the timing pulley  364  also rotates the timing pulley  365 . Since the timing pulley  365  is coupled to the wheel  377 , the wheel  377  rotates along with the timing pulley  365 . Thus, the rotation of the output shaft  373  rotates all of the upper and lower plate drive wheels  364 ,  365 ,  377 ,  378 . 
   The tab assembly device  356  is also provided with a belt tensioner wheel  374  which is adjustable for maintaining proper tension of the belt  366  around the upper plate timing pulleys  364 ,  365 . 
   A receiver arm frame  362  is mounted to each pair of the upper and lower plate drive wheels for horizontally reciprocating in a U-shaped path in response to the rotation of the drive wheels  364 ,  365 ,  377 ,  378 . The receiver arm frame  362  is a generally plate-like structure having a pair of bearings  368 , which receive one end of a pin  369 . Each of the upper plate timing pulleys  364 ,  365  is provided with an upper drive wheel pivot pin hole  384  that fixedly receives the other end of the pin  369 . Similarly, a receiver arm frame  362  is also mounted to the lower plate wheel  377  and driven gear  378  with bearings  368  and pins  369 . The receiver arm frames  362  are mounted to the upper plate timing pulleys  364 ,  365  and the lower plate wheel  377  and driven gear  378  at diametrically-opposed juxtaposition so that the upper and lower receiver arm frames  362  have an opposed reciprocal movement. 
   Attached to the receiver arm frames  362  are a pair of receiver arms  360  having attached tab receivers  220 , force relievers  260 , and air lines  254  (air lines are not shown in  FIG. 27  for clarity) having the same structure and configuration as for the first embodiment. The receiver arms  360  are spaced on the receiver arm frame  362  such that each arm  360  is aligned with an opening  154  in the upper row of the die shoe  352 . 
   It should be noted that while each receiver arm frame  362  is sized to mount two receiver arms  360  to effect the simultaneous pick-up and assembly of two tabs  332 , it is within the scope of the invention for each receiver arm frame  362  to mount only one receiver arm  360  or more than two receiver arms  360 . It is also within the scope of the invention for multiple receiver arm frames  362  to be mounted to a single base plate  376 . Also, the invention can have one, two, or more tab assembly devices  356 . The number of receiver arms  360  and tab assembly devices  356  can be adjusted as needed for a given assembly configuration depending on the type and size of product being assembled. 
   The second embodiment of the tab assembly mechanism  354  operates in a similar manner to the first embodiment, except that as the plastic web  320  moves vertically through the assembly station  16 , and the tab closures  332  are picked up from the tab punch assembly  102  and moved horizontally to the lid support assembly  104 . Additionally, an assembled lid  330  occupying a lower row in the plastic web  320  is trimmed from the plastic web  320  at the same time that a tab closure  332  in the row above is assembled to a lid  330  and a second tab closure  332  is picked up from the plastic web  320 . 
     FIGS. 29-31  illustrate the same significant steps in the operation of the second embodiment as disclosed in the first embodiment.  FIGS. 29-31  are arranged in pairs  29 - 29 A,  30 - 30 A, and  31 - 31 A. The first drawing of each pair illustrates the operation from the section line  25 - 25  or side view and shows the operation of the tab punch  108  and lid punch assembly  302  with their corresponding dies. The second drawing of each pair, the “A” drawing, illustrates the operation from a top view and shows the operation of the tab punch  108  and the lid support assembly  104 . 
   In  FIGS. 29 and 29A , as with the first embodiment shown in  FIG. 17 , the operation is assumed to begin when the punch tool assembly  300  is near its backstroke. The tab punch assembly  102  and lid punch assembly  302  are in operable juxtaposition to the tab die  156  for punching out the tab closures  332  in the upper row and the assembled lid  330  in the lower row. The receiver arms  360  on the upper receiver frame  362  are aligned with the tab dies  156  to pick up the punched tab closures  332 . The receiver arms  360  on the lower receiver arm frame  362  are already carrying a previously punched tab closure  332  and are aligned with the openings  154  for the subsequent assembly of the tab closures  332  to the corresponding lids  330 . In general, the separation of the tab closures  332  from the plastic web  320 , the retention of the tab closures  332  on the tab receivers  220  by an applied vacuum, and the mounting of the tab closures  332  to the lids  330  are identical to these operations performed with the first embodiment. 
   The plastic web  320  is advanced to an indexed position in which a row of tab closures  332  and lids  330  is aligned with the tab dies  156  and the access openings  154 , respectively, comprising the top row of the die assembly  350 . At the same time, a row of lids  330  with assembled tab closures  332  is aligned with the lid die  340  comprising the bottom row of the die assembly  350 . 
   Referring to  FIGS. 30 and 30A , the tab assembly mechanism  354  is then advanced toward the die assembly  350  to extend the tab receivers  220  into and through the die openings  158  to clear the die openings  158  of any tab closures  332  that might remain from a previous operation. The tab assembly mechanism  354  is then withdrawn to move the tab receivers  220  into the standby position, and the punch tool assembly  300  is advanced toward the die assembly  350 . 
   Referring to  FIGS. 31-31A , as the punch tool assembly  300  moves toward the forward stroke limit, the lid support assembly  104  is received within the lids  330 , the tab punch assembly  102  initiates contact with the plastic web  320  for removal of a tab closure  332 , and the lid punch assembly  302  initiates contact with the plastic web  320  for removal of the assembled lid  330 . The tab closures  332  are removed from the plastic web  320  and are picked up by the tab receivers  220  mounted to the receiver arms  360  attached to the upper receiver arm frame  362 . In the same operation, the tab closures  332  attached to the receiver arms  360  on the lower receiver arm frame  362  are assembled to the lids  330 . In the same operation, the assembled lids  330  are separated from the plastic web  320  and pushed through the lid die opening. 
   After the tab closures  332  are picked up by the upper receiver arms  360  and the tab closures  332  carried by the lower receiver arms  360  are mounted to the lids  330 , the tab assembly devices  356  are moved on the rails away from the die shoe  352  a sufficient distance such that the receiver arms  360  can be reciprocated without contacting the die shoe  352 , the punch assembly  300  is moved toward its backstroke position, and the plastic web  320  is indexed one row. The tab closures  332  held by the upper receiver arms  360  are moved horizontally into position by the reciprocating movement of the receiver arm frames  362  for assembly to the lids  330  in response to the servomotors  372 . At the same time, the lower receiver arms  360 , having assembled their tab closures  332  to the lids  330 , are moved horizontally into position for receiving a new set of tab closures  332  as they are separated from the plastic web  320 . This process is repeated continuously so long as the plastic web  320  is supplied to the assembly station  16 . 
     FIG. 32  illustrates an alternative lid support assembly  404 , which can be used in place of any of the previously described lid support assemblies  104 . The lid support assembly  404  has the same general structure as the previously described lid support assemblies  104  in that it has a base  426  and a support element  428  having an exterior surface  430 . The main difference in the lid support assembly  404  is that the exterior surface  430  is does not conform to the shape of the lid. For example, the exterior surface  430  comprises a peripheral wall, which has a diameter less than the inner diameter of the lid. While the exterior surface  430  does include a top surface support  436 , a reservoir support  438 , and a drink opening support  440 , it does not have the upper support surface  134  as found in the previously described lid support assemblies  104 . The structure of the lid support assembly  404  is such that it generally supports only those areas of the lid against which the tab closure will contact during assembly. This structure reduces the surface area of the lid support assembly  404  that will contact the lid and thereby reduces the likelihood that the lid will become stuck on the lid support assembly  404  and ease the removal of the lid from the lid support assembly  404 . 
   While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.