Abstract:
A rim rolling apparatus is provided having a plurality of rim rolling screws, a motor and a pneumatic cooling circuit. Each screw has a hot section and a cool section provided downstream of the hot section. The motor is configured to drive the screws in rotation to feed thermoformed articles between the screws to roll lips of the articles. The pneumatic cooling circuit extends within the screw from an exit end towards an entrance end. The cooling circuit is provided in thermally conductive relation with the cool section and insulated from the hot section.

Description:
RELATED PATENT DATA 
       [0001]    This application claims priority to U.S. Provisional Patent Application Ser. No. 61/218,972 which was filed Jun. 21, 2009, entitled “Rim Rolling Screw Having Pneumatic Cooling”, the entirety of which is incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention pertains to lip and rim rolling machines. More particularly, the present invention relates to rim rolling machines for forming a curled lip on a thermoformed plastic container. 
       BACKGROUND OF THE INVENTION 
       [0003]    Arrays of rim rolling screws are known. Hot sections are used to heat up a lip edge of a thermoformed article before conveying the lip edge between the array of screws to curl and form a rolled lip edge. Cool sections of screws are used to then capture the curled and formed rolled lip edge. Techniques have been used to provide separate hot sections and cold sections. Techniques have also been used to cool the cool section using a liquid cooling system. 
       SUMMARY OF THE INVENTION 
       [0004]    A rim rolling machine having rim rolling screws with heated hot and cool sections is provided. The hot section is connected to the cool section with a connector that reduces any heat transfer from the hot section to the cool section. Furthermore, a flow of air is delivered through both the cool and hot sections, opposite the direction that cups are delivered along the screws, where air flows along an inner surface of the cool section, but travels through an isolation tube inside the hot section to prevent cooling of this section. The flow of air also serves to cool bearings that support each screw at each end. Furthermore, the rim rolling machine has a mounting mechanism for quickly and easily mounting and removing tubes of a rim roller screw. Finally, the rim rolling machine has a spring, or pneumatic cylinder for applying constant pressure when mounting a tube of a rim roller screw, thereby accommodating changes in length of the tube resulting from oven heating without imparting additional undue lateral compressive loads on a bearing race. 
         [0005]    According to one aspect, a rim rolling apparatus is provided having a plurality of rim rolling screws, a motor and a pneumatic cooling circuit. Each screw has a hot section and a cool section provided downstream of the hot section. The motor is configured to drive the screws in rotation to feed thermoformed articles between the screws to roll lips of the articles. The pneumatic cooling circuit extends within the screw from an exit end towards an entrance end. The cooling circuit is provided in thermally conductive relation with the cool section and insulated from the hot section. 
         [0006]    While the invention was motivated in addressing rim rolling screws and machines by providing improved and simplified constructions for a rim rolling screw having both hot and cold sections in one screw, it is in no way so limited. The invention is only limited by the accompanying claims as literally worded, without interpretative or other limiting reference to the specification, and in accordance with the doctrine of equivalents. Other aspects and implementations are contemplated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Preferred embodiments of the invention are described below with reference to the following accompanying drawings. 
           [0008]      FIG. 1  is an exit end perspective view of a rim rolling machine. 
           [0009]      FIG. 2  is a vertical sectional perspective view of an exit end of one rim roller screw from the rim rolling machine of  FIG. 1 . 
           [0010]      FIG. 3  is a vertical sectional perspective view of an entrance end of the rim roller screw of  FIG. 2 . 
           [0011]      FIG. 3A  is a perspective view of the rim roller screw of  FIGS. 2-3 . 
           [0012]      FIG. 4  is a vertical side view of the rim roller screw of  FIGS. 2-3 . 
           [0013]      FIG. 5A  is an enlarged partial breakaway side view of the downstream, entrance end of the rim roller screw of  FIG. 4 . 
           [0014]      FIG. 5B  is an enlarged partial breakaway side view of the upstream, exit end of the rim roller screw of  FIG. 4 . 
           [0015]      FIG. 6  is centerline sectional view taken along arrow  6  of  FIG. 5A . 
           [0016]      FIG. 6A  is an enlarged view taken from encircled region  6 A of  FIG. 6 . 
           [0017]      FIG. 7  is a centerline sectional view taken along arrow  7  of  FIG. 5B . 
           [0018]      FIG. 7A  is an enlarged view taken from encircled region  7 A of  FIG. 7 . 
           [0019]      FIG. 8  is a vertical sectional perspective view of the rim rolling machine of  FIG. 1  illustrating a top-most rim roller screw in vertical centerline sectional view. 
           [0020]      FIG. 9  is a frontal vertical sectional view of the rim rolling machine of  FIG. 8 . 
           [0021]      FIG. 10  is a component perspective view of a screw exit pulley assembly. 
           [0022]      FIG. 11  is a screw drive assembly for driving three screw exit pulley assemblies of  FIG. 10 . 
           [0023]      FIG. 12  is an exit end perspective view, taken from the front, corresponding with that depicted in  FIG. 1 , with portions removed, showing a radial adjustment mechanism for radially adjusting position of the three rim roller screws. 
           [0024]      FIG. 12A  is an enlarged partial perspective view of the radial adjustment mechanism of  FIG. 12 . 
           [0025]      FIG. 13  is an exit end perspective view, taken from the rear, with portions removed, showing the radial adjustment mechanism of  FIGS. 12-12A . 
           [0026]      FIG. 13A  is an enlarged partial perspective view of the radial adjustment mechanism of  FIG. 13 . 
           [0027]      FIG. 14  is an entrance end perspective view, taken from the rear of the rim rolling machine of  FIGS. 1-14 . 
           [0028]      FIG. 15  is a perspective view corresponding with that shown in  FIG. 14  showing details of the frame and oven cover opening mechanism shown in a closed position. 
           [0029]      FIG. 16  is a perspective view of the rim rolling machine of  FIG. 15  showing details of the frame and oven cover opening mechanism shown in an open position. 
           [0030]      FIG. 17  is an enlarged partial perspective view along an exit end from the rear of the rim rolling machine of  FIGS. 1-16  showing portions of the oven cover opening mechanism. 
           [0031]      FIG. 18  is an exit end perspective view, taken from the rear, with cover portions removed, showing a mechanism for inserting and removing rim roller screws from the rim rolling machine. 
           [0032]      FIG. 19  is an exit end view of a selected tube assembly for a rim roller screw. 
           [0033]      FIG. 20  is an entrance end view of a selected tube assembly for a rim roller screw. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
         [0035]    A rim rolling machine  10  is provided for heat forming rolled lip edges on thermoformed articles, such as cups, according to one aspect of the present invention. As shown in  FIG. 1 , rim rolling machine  10  includes a structural frame  12  comprising an array of side plates and cross members. A plurality of rim roller screws  14 - 16  are supported by frame  12  so as to be driven in rotation to deliver thermoformed articles through the machine. Additionally or optionally, further rollers can be provided to guide and support articles as they are conveyed between the screws  14 - 16 . An upstream portion of each screw  14 - 16  is supported within an oven  18  that heats up screws  14 - 16  so as to provide heat that is used to curl and roll a lip edge on cups that are conveyed between screws  14 - 16 . 
         [0036]    A cooling system  19  is provided on machine  10  in order to cool a downstream end of each screw  14 - 16  in order to provide a mechanism to cool and capture a curled lip edge on individual cups after they have been formed along a heated upstream section of each screw  14 - 16 . More particularly, a pneumatic source of air  20  is provided by a high pressure motor-driven fan  22  to deliver a flow of air via individual tubes  24 - 26  to an inlet on each rim roller screw  14 - 16 , respectively. 
         [0037]    A control system box  28  is supported by frame  12  for containing electrical and pneumatic controls  30 . An electrical screw drive motor  32  is also supported by frame  12  to drive rim roller screws  14 - 16  in rotation using the drive belt system described below with reference to  FIG. 11 . 
         [0038]      FIGS. 2 and 3  illustrate construction of rim roller screw  14 . Screws  15  and  16  are similarly constructed. More particularly, rim roller screw  14  includes an entrance end cylindrical tube  38 , an exit end cylindrical tube  40 , and a heat isolating connector  42  that joins together tubes  38  and  40 , as shown in  FIG. 3 . A helical groove  21  is provided in the outer surface of screw  14  according to known techniques to progressively form a rolled rim on a cup that is conveyed between the rotating screws  14 - 16 . According to one construction, tubes  38  and  40  are formed from aluminum tube and connector  42  is formed from steel. Other materials and constructions can be used. 
         [0039]    Connector  42  joins together tubes  38  and  40  while also thermally isolating tubes  38  and  40  from one another. More particularly, tube  38  is heated up within oven  18  (see  FIG. 1 ) via radiant oven heating elements  120  (see  FIG. 8 ). A heated outer surface on tube  38  heats up a cup lip via groove  21 , thereby softening up the lip and enabling progressive advance of the lip along the groove to shape and roll the lip. Once formed, the rolled lip is cooled by contact within groove  21  around tube  40 , as tube  40  is cooled by a flow of pneumatic fluid (air) that is delivered there through. Connector  42  is constructed in a manner that reduces heat transfer from tube  38  to tube  40 . Likewise, connector  42  reduces transmission of cold from tube  40  to tube  38 . 
         [0040]    As shown in  FIG. 2 , connector  42  includes a cylindrical central hub  70  that defines a cylindrical inner bore  72 . A pair of axially spaced-apart circumferential bulkheads  74  and  76  extend outwardly of hub  70  in a radial direction. Each bulkhead terminates in a threaded cylindrical outer surface  78  and  80 , respectively. Threaded surfaces  78  and  80  mate in assembly with complementary threaded cylindrical inner surfaces  79  and  81  in tubes  38  and  40 , respectively. Threaded portions  79  and  81  are limited in length to ensure that a circumferential gap  88  is provided between tubes  38  and  40 , thereby preventing heat transmission through any direct contact from tube  38  into tube  40 . A circumferential gap  82  is provided between bulkheads  74  and  76 . A baffle plate  44  is secured with three fasteners  45  onto connector  42  to cover bore  72  and limit how much air flows through plate  44  so that more air is directed through bores  84 . A plurality of bores, or apertures  86  allow some air to flow through bore  72 . A circumferential array of bores  84  along a radial outer portion of each bulkhead  74  and  76  provides a path for air, or pneumatic fluid to pass through connector  42 . Apertures  84  ensure a flow of cooling air along an inner surface  90  of tube  40  that is delivered from inlet member  34 . 
         [0041]    In order to prevent cooling of tube  38 , a flow isolation tube  46  is supported coaxially within tube  38  as shown in  FIG. 2 . Tube  46  is supported at an upstream end, adjacent connector  42 , within a frustoconical flange  48 . Tube  46  is supported at a downstream end via a cylindrical end plate  114  (see  FIG. 3 ). Flange  48  and end plate  114  are welded onto opposite ends of tube  46 . Optionally, they can be press fit or glued together. 
         [0042]    Flow isolation tube  46  is retained inside of tube  38  by flange  48  and end plate  114 , which fit smoothly inside of tube  38 , as shown in  FIGS. 2 and 3 . Connector  42  retains flange  48  at one end, while a C-shaped spring clip  110  traps an opposite end of tube  38  by being placed into a circumferential groove  112  on an inner surface of tube  48 . In this way, C-shaped spring clip  110  can be removed using a tool in order to insert and remove tube  46  within tube  38 . According to one construction, tube  46 , flange  48  and end plate  114  are made from stainless steel. Optionally, they can be made from steel, aluminum, copper, or any other suitable structural material. Further optionally, an insulating material can be used or added to an inner or outer surface. 
         [0043]    An exit end plate  58  is provided at an exit of screw  14  as shown in  FIG. 2 . End plate  58  is secured to a belt drive pulley  56  with a plurality of threaded fasteners  60 . A drive assembly  50  is provided by end plate  58 , pulley  56 , and inlet member  34 . A cylindrical bearing  62  supports pulley  56  and end plate  58  for rotation about inlet member  34 . A flange  52  on member  34  is secured to a support bracket, or frame member with a plurality of threaded fasteners (not shown) that pass through hole  54  to support an end of screw  14 . Such bracket is adjustable in radial position in order to adjust for different sized thermoformed articles, as is already understood according to numerous techniques in the art. Further details of one construction are shown in  FIGS. 12-13 . 
         [0044]    A nut (or a snap ring)  68  is used to trap an inner race of bearing  62  onto member  34 . An outer race of bearing  62  is trapped between pulley  56  and end plate  58  using a circumferential array of threaded fasteners. 
         [0045]    An end plate  100  is provided at the entrance of screw  14  (see  FIG. 3 ), or downstream end of the pneumatic cooling fluid, for cooling a cylindrical bearing  98 . Cylindrical bearing  62  (see  FIG. 2 ) is provided at the opposite end of screw  14  and is cooled by inlet member  34  as air flows through member  34 . A cylindrical array of bores  106  are provided along an outer cylindrical periphery of end plate  100  in order to enable the flow of cooling air that leaves tube  46  to exit tube  14 . The flow of air through bores  106  of plate  100  cools plate  100 , thereby cooling bearing  98 . 
         [0046]    A pneumatic cylinder  92  is provided at the entrance end of each screw, such as screw  14  of  FIG. 3 . Cylinder  92  facilitates quick mounting and demounting of screws  14  from a machine. More particularly, entrance end of screw  14  provides a tapering circumferential bevel  118  on tube  38  and a complementary tapering circumferential bevel  119  on end plate  100  (see  FIG. 3 ). In addition, exit end of screw  14  provides a tapering circumferential bevel  64  on tube  40  and a complementary tapering circumferential bevel  66  on a drive lug, or end plate  58  (see  FIG. 2 ). By retracting cylinder  92  (of  FIG. 3 ), screw  14  can be removed (with the oven open) as the pairs of mating bevels separate, allowing withdrawal of tubes  38 ,  40  and connector  42 . By extending cylinder  92  after inserting a new screw  14 , the screw  14  is trapped or mated between end plates  58  and  100  (see  FIGS. 2 and 3 ). A boss  96  is seated on piston  94  and traps an inner race of bearing  98  in cooperation with washer plate  102 . Washer plate  102  is mounted with three threaded fasteners  104  onto boss  96 . 
         [0047]      FIG. 4  is a vertical side view of the rim roller screw  14  of  FIGS. 2-3 . The pneumatic cylinder, or piston  52 , drive assembly  50 , bearing assembly  51 , tubes  38  and  40 , and connector  42  are illustrated in assembly. 
         [0048]      FIG. 5A  is an enlarged partial breakaway side view of the downstream, entrance end of the rim roller screw of  FIG. 4 . The arrangement of pneumatic cylinder  92 , bearing assembly  51  and tube  38  are shown. 
         [0049]      FIG. 5B  is an enlarged partial breakaway side view of the upstream, exit end of the rim roller screw of  FIG. 4 . The arrangement of connector  42  and drive assembly  50  are shown in relation to tube  40 . 
         [0050]      FIG. 6  is a centerline sectional view taken along arrow  6  of  FIG. 5A . Connection of pneumatic cylinder  92  with tube  38  is shown. 
         [0051]      FIG. 6A  is an enlarged view taken from encircled region  6 A of  FIG. 6 . C-shaped spring clip  110  is shown positioned within groove  112 . 
         [0052]      FIG. 7  is a centerline sectional view taken along arrow  7  of  FIG. 5B . Arrangement of connector  42  is shown. 
         [0053]      FIG. 7A  is an enlarged view taken from encircled region  7 A of  FIG. 7 . Positioning of cylindrical bearing  62  is shown. 
         [0054]      FIG. 8  is a vertical sectional perspective view of the rim rolling machine of  FIG. 1  illustrating a top-most rim rolling screw in vertical centerline sectional view. Resistive heating element assemblies  120  are shown within oven  18  in relation to screws  14  and  16 . 
         [0055]      FIG. 9  is a frontal vertical sectional of the rim rolling machine of  FIG. 8 . Arrangement of resistive heating elements  120  are shown in relation to screws  14  and  16 . 
         [0056]      FIG. 10  is a component perspective view of a screw exit pulley drive assembly  50 . Drive assembly  50  includes belt drive pulley  56  and end plate  58 . End plate  58  has an enlarged frustoconical bump  59 . A complementary surface is formed in the beveled end of tube  40  in order to align the screw against end plate  58 . 
         [0057]      FIG. 11  is a screw drive assembly for driving three screw exit pulley assemblies of  FIG. 10 . The drive assemblies  50  for each of the three screws are shown being driven via a serpentine belt  57  that is driven by motor  32 . Idler wheels,  61 ,  63 ,  65  cooperate with turning wheel  67  and  69  to drive assemblies  50  all in the same rotational direction (thereby driving the respective screws). A tensioning arm  71  is tensioned by a stretched coil spring  73 . 
         [0058]      FIG. 12  is an exit end perspective view, taken from the front, corresponding with that depicted in  FIG. 1 , with portions removed, showing a radial adjustment mechanism for radially adjusting position of the three rim rolling screws. A radial adjustment linkage  122  is shown for radially adjusting in and out one end of the screws. 
         [0059]      FIG. 12A  is an enlarged partial perspective view of the radial adjustment mechanism of  FIG. 12 . Further details are shown for the radial adjustment linkage assembly  122 . More particularly, linkage assembly  122  comprises a plurality of individual linkages  126 - 135 , each joined together for pivotal motion with a rotary bearing assembly. Linkages  126 - 128  each comprise an L-shaped screw toggle bracket that has a bearing housing  158  that seats with a pair of cylindrical bearings for pivotal movement about a stationary post, or stump shaft  159  that is affixed to a frame member, or side plate of machine  10 . An upper motion toggle bracket  130  and a lower motion toggle bracket  133  couple together linkages  126 - 128  via connecting linkages  129 , A  131 ,  132  and  134 . Toggle bracket  130  has a central pivot connection that mates with a cylindrical bearing to a frame of machine  10 . Toggle bracket  133  has four pivotal connections and has a U-shaped configuration with a second pivotal connection coupled for pivotal motion to a frame of machine  10 . A fourth connection of linkage  133  is pivotally coupled with a bearing to a common shaft linkage  135  that is affixed at an opposite end to a longitudinal shaft (not shown) that extends to an opposite end of machine  10  and pivotally couples with an adjustable common shaft linkage  155  (see  FIG. 13A ) of a similar linkage  122 ′ that radially adjust an opposite end of each screw  14 - 16 . 
         [0060]      FIG. 13  is an exit end perspective view, taken from the rear, with portions removed, showing the radial adjustment mechanism of  FIGS. 12-12A . A radial adjustment linkage assembly  122 ′ is shown at an opposite end of the rim rolling apparatus  10  for radially adjusting in sequence an opposite end of each screw. 
         [0061]      FIG. 13A  is an enlarged partial perspective view of the radial adjustment mechanism of  FIG. 13 . The radial adjustment linkage  122 ′ is shown in enlarged greater detail for radial adjusting screws  14 - 16  to accommodate different sized articles during a lip rolling operation. More particularly, linkage assembly  122 ′ comprises a plurality of individual linkages  146 - 148 , each joined together for pivotal motion with a rotary bearing assembly. Linkages  146 - 148  each comprise an L-shaped screw toggle bracket that has a bearing housing  158  that seats with a pair of cylindrical bearings for pivotal movement about a stationary post, or stump shaft  159  that is affixed to a frame member, or side plate of machine  10 . An upper motion toggle bracket  150  and a lower motion toggle bracket  153  couple together linkages  146 - 148  via connecting linkages  149 ,  151 ,  152  and  154 . Toggle bracket  150  has a central pivot connection that mates with a cylindrical bearing to a frame of machine  10 . Toggle bracket  153  has four pivotal connections and has a U-shaped configuration with a second pivotal connection coupled for pivotal motion to a frame of machine  10 . A fourth connection of linkage  153  is pivotally coupled with a bearing to an adjustable length common shaft linkage  155  that is affixed at an opposite end to a longitudinal shaft (not shown) that extends to an opposite end of machine  10  and pivotally couples with adjustable common shaft linkage  135  (see  FIG. 12A ) of a similar linkage  122  that radially adjust an opposite end of each screw  14 - 16 . A rotary hand crank  157  and gearbox (not shown) rotate the longitudinal shaft that pivots linkages  135  (see  FIG. 12A) and 155  (see  FIG. 13A ). 
         [0062]    A clamp collar  160  is affixed onto one arm of linkage  146  (as well as on linkages  147  and  148 ) using threaded fasteners (or alternatively by welding). Clamp collar  160  has a cylindrical bore that receives a respective pneumatic cylinder  92  for mounting and removing tubes of each screw  14 - 16  by extending and retracting cylinder  92  by controlling delivery of a pneumatic source, such as an air supply line. Pneumatic cylinder  92  provides a set pressure when trapping tubes of each screw  14 - 16  and acts like a spring, enabling for thermal expansion and contraction of each tube caused by heating during operation in an oven. If a hydraulic cylinder was used, undue axial loads are placed on each bearing of screws  14 - 16 , leading to premature bearing failure. According to one construction, pneumatic cylinder  92  is an SMC double rod pneumatic cylinder, Model No. NCGWBN63-0200-DUM01488, sold by SMC  10100  SMC Blvd., Noblesville, Ind.  46060 . 
         [0063]      FIG. 14  is an entrance end perspective view, taken from the rear of the rim rolling machine of  FIGS. 1-14 . Rim rolling apparatus  10  is shown with components omitted for clarity. 
         [0064]      FIG. 15  is a perspective view corresponding with that shown in  FIG. 14  showing details of the frame and oven cover opening mechanism shown in a closed position. A cover lift mechanism  124  is depicted on rim rolling apparatus  10 . 
         [0065]      FIG. 16  is a perspective view of the rim rolling machine of  FIG. 15  showing details of the frame and oven cover opening mechanism shown in an open position. Details of the cover lift mechanism (with other portions omitted) are shown in a lifted configuration for lifting a cover on the oven to access internal components, such as the screws contained therein. 
         [0066]      FIG. 17  is an enlarged partial perspective view along an exit end from the rear of the rim rolling machine of  FIGS. 1-16  showing portions of the oven cover opening mechanism. Further details are shown for the cover lift mechanism  124 . 
         [0067]      FIG. 18  is an exit end perspective view of rim rolling machine  10  opened up to show screw tubes  38 ,  40  of screw assembly  16  being removed during maintenance and/or when changing the screw roll. As shown in  FIG. 18 , pneumatic piston  16  has been retracted so as to move apart bearing assembly  51  from drive assembly  50 , thereby freeing tubes  38  and  40  (as a single assembly) for removal from machine  10 . Screw assemblies  14  and  15  operate in a similar manner to enable insertion and removal of the respective tube assemblies of each screw. 
         [0068]      FIG. 19  shows the manner in which pneumatic cylinder  92  connects to bearing assembly  51 . More particularly, a distal end of piston  94  is threaded into a complementary bore within bearing assembly  51 . Bearing assembly  51  includes a sealed deep groove steel ball bearing  98  that is received in an entrance end plate  100 . A circumferential outer bevel on plate  100  mates with a complementary bevel within tube  38  as pneumatic pressure is applied in assembly using piston  92 , thereby positively seating tube  38 . This pressure also seats tube  40  (of  FIG. 20 ) with complementary bevels on an exit end plate  58  during assembly. Piston  92  and drive assembly  50  are fixed on to a frame at spaced apart locations (namely, between respective brackets  126 ,  146 ;  128 ,  148 ; and  127 ,  147 ). Piston  92  provides a pneumatic spring that applies a steady pressure, even when tubes  38  and  40  lengthen as a result of thermal expansion in an oven. In contrast, if a hydraulic actuator or mechanically-fixed actuator or mount is used, undue stress is applied axially to the inner bearing races, which would lead to premature failure of bearings  62  and  98 . 
         [0069]    In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.