Abstract:
A thermoformable web chain rail assembly is provided having a chain and a chain rail. The chain has a series of alternating and interconnected roller links and pin links. The pin links include at least one pin extending through an adjacent one of the roller links and the pin links. A terminal portion of the pin extends beyond the roller link and the pin link with a roller affixed for rotation about the terminal portion of the pin for each of the at least one pins. The chain rail has an upper conveying raceway and a lower return raceway. The upper raceway includes a first linear guide surface provided beneath the first roller of each chain link and a second linear guide surface provided above the second roller of each chain link.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure pertains to chains and chain rails. More particularly, this disclosure relates to thermoforming chain rails and chains. 
       BACKGROUND OF THE INVENTION 
       [0002]    Techniques are known for conveying web and sheet materials through processing operations, such as conveyors for transporting a thermoformable web through a conveyor oven and a thermoforming machine. One conveyor uses a chain rail  11  and chain  13  shown in  FIG. 3 . More particularly, chain  13  includes elongate pins  17  that travel within slot  21  formed in an aluminum extrusion  23 . Over time, pin  17  wears out and forms a flat surface due to sliding contact with extrusion  23  along slot  21 . Roller  15  of chain  13  rides atop a flat shoulder, or raceway  19  integrally formed in extrusion  23 . Improvements are needed in order to eliminate wear of pin  21  which reduces the ability of chain  13  to counteract lateral forces on chain  13  resulting from a pierced sheet imparting lateral forces to chain  13 . Further improvements are needed because aluminum extrusion  23  also contains ports for cooling fluids, and aluminum extrusion over time can degrade and leak due to inter-granular corrosion. Further, formation of long sections of extrusion  23 , which is typically anodized, is difficult to manufacture. Extremely long extruded parts are difficult to form and anodize, for example, such as typical chain rails of lengths around thirty feet in length. Accordingly, improvements are needed in corrosion resistance of materials and manufacturability of chain rails. 
       SUMMARY OF THE INVENTION 
       [0003]    According to one aspect, a thermoforming chain rail assembly is provided having a chain and a chain rail. The chain has a series of alternating and interconnected roller links and pin links. The roller link has a first bushing and a second bushing coupling together a first roller link plate with a parallel second roller link plate, a first roller and a second roller provided about the first bushing and the second bushing between the first roller link plate and the second roller link plate. The pin link has a first elongate pin and a second elongate pin coupling together a first pin link plate and a second pin link plate while overlapping the first roller link plate and the second roller link plate. The first elongate pin passes through the second bushing of the roller link and the second elongate pin passes through a first bushing of another roller link, the first elongate pin and the second elongate pin each extending through and beyond the first pin link plate and receiving a pin roller thereabout captured on each respective pin for rotation. The spike extends upwardly from one of the second roller link plate and the second pin link plate. The chain rail has an upper conveying raceway and a lower return raceway, the upper raceway including a first linear guide surface provided beneath the first roller of each chain link and a second linear guide surface provided above the second roller of each chain link. 
         [0004]    According to another aspect, a thermoformable web chain rail assembly is provided having a chain and a chain rail. The chain has a series of alternating and interconnected roller links and pin links. The pin links include at least one pin extending through an adjacent one of the roller links and the pin links. A terminal portion of the pin extends beyond the roller link and the pin link with a roller affixed for rotation about the terminal portion of the pin for each of the at least one pins. The chain rail has an upper conveying raceway and a lower return raceway. The upper raceway includes a first linear guide surface provided beneath the first roller of each chain link and a second linear guide surface provided above the second roller of each chain link. 
         [0005]    According to yet another aspect, a thermoformable web conveyor chain is provided. The chain has a series of alternating and interconnected roller links and pin links. The roller link has a first bushing and a second bushing coupling together a first roller link plate with a parallel second roller link plate, a first roller and a second roller provided about the first bushing and the second bushing between the first roller link plate and the second roller link plate. The pin link has a first elongate pin and a second elongate pin coupling together a first pin link plate and a second pin link plate while overlapping the first roller link plate and the second roller link plate. The first elongate pin passes through the second bushing of the roller link and the second elongate pin passes through a first bushing of another roller link, the first elongate pin and the second elongate pin each extending through and beyond the first pin link plate and receiving a pin roller thereabout captured on each respective pin for rotation. The spike extends upwardly from one of the second roller link plate and the second pin link plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Preferred embodiments of the disclosure are described below with reference to the following accompanying drawings. 
           [0007]      FIG. 1  is perspective view from above of a portion of a thermoforming line including a conveyor oven and a web conveyor with a pair of chain rails and chains according to one aspect. 
           [0008]      FIG. 2  is a perspective view from above of the thermoforming line and web conveyor of  FIG. 1  with the conveyor oven removed. 
           [0009]      FIG. 3  is a prior art thermoforming chain rail and chain cross-sectional view. 
           [0010]      FIG. 4  is an exploded perspective view of one segment of a roller link and a pin link for the chain of  FIGS. 1-2 . 
           [0011]      FIG. 5  is an outside perspective view of the segment of chain of  FIG. 4 . 
           [0012]      FIG. 6  is an inside perspective view of the segment of chain of  FIGS. 4 and 5 . 
           [0013]      FIG. 7  is a vertical sectional view of one chain rail taken along line  7 - 7  of  FIG. 2 . 
           [0014]      FIG. 8  is an enlarged vertical side view of the right chain track assembly of  FIG. 2  illustrating the right chain rail, but with portions removed to facilitate viewing, the right chain tensioner assembly, and the rear support rail assembly. 
           [0015]      FIG. 9  is a left end view of the chain track assembly of  FIG. 8 . 
           [0016]      FIG. 10  is a right end view of the chain track assembly of  FIG. 8 . 
           [0017]      FIG. 11  is an upstream end view of the chain exit assembly of  FIG. 8  according to an alternative construction. 
           [0018]      FIG. 12  is an enlarged view of the alternative construction chain rail of  FIG. 11  taken from encircled region  12  of  FIG. 11 . 
           [0019]      FIG. 13  is perspective view from upstream of the chain exit assembly of  FIGS. 11 and 12 . 
           [0020]      FIG. 14  is a perspective view of the chain rail assembly with the chain removed. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    This disclosure 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). 
         [0022]    In  FIG. 1 , a representation of an illustrative thermoformable web conveyor having a thermoforming chain rail assembly for supporting and moving a sheet of thermoformable material through an oven and a thermoforming machine is shown and identified by reference numeral  12 . More particularly, conveyor  12  is shown extending through an oven  14 , a thermoforming machine  16  and an exterior guard  18  of a thermoforming line  10 . Conveyor  12  includes an end frame  20  at an upstream end, and is supported downstream by a frame  22  of thermoforming machine  16 . 
         [0023]    As shown in  FIG. 2 , oven  14  (of  FIG. 1 ) has been removed in order to see components of thermoformable web conveyor  12 . More particularly, conveyor  12  includes a pair of elongate and laterally spaced-apart chain track assemblies  24  and  26 . Each chain track assembly  24  and  26  includes a structural support rail  28  and  30  affixed with fasteners to a respective chain, or frame rail  32  and  34 . A chain drive and tension assembly  36  and  38  is provided at an upstream end of each chain rail  32  and  34 , respectively. A chain exit end assembly  40  and  42  is provided at a downstream end of each chain rail  32  and  34 , respectively. Support rails  28  and  30  are affixed at an upstream end to machine frame  22  and frame  22  of thermoforming machine  16  at a downstream end. Rails  28  and  30  serve as a structural reinforcement and support to chain rails  32  and  34 , respectively. Except for improvements to chain rails  32  and  34  (and the contained chain), conveyor  12  is constructed according to teachings of U.S. Pat. No. 5,806,745, herein incorporated by reference. Chain rails  32  and  34 , according to such teaching, can be laterally adjusted to match wide of a thermoformable web, or sheet being conveyed by conveyor  12  during a thermoforming operation. Optionally chain rails  32  and  34  can be stationary relative to one another. 
         [0024]      FIG. 4  illustrates in exploded perspective view one segment of a roller link  46  and a pin link  48  for chain  44  as used in chain rails  32  and  34  (of  FIGS. 1-2 ). Roller link  46  includes a first bushing  62  and a second bushing  64  coupling together a first roller link plate  50  with a parallel second roller link plate  52 , a first roller  58  and a second roller  60  provided about the first bushing  62  and the second bushing  64  between the first roller link plate  50  and the second roller link plate  52 . Pin link  48  includes a first elongate pin  70  and a second elongate pin  72  coupling together a first pin link plate  54  and a second pin link plate  56  while overlapping the first roller link plate  50  and the second roller link plate  52 , the first elongate pin  70  passing through the second bushing  64  of the roller link  46  and the second elongate pin  72  passing through a first bushing  62  of another, adjacent and successive roller link (not shown). The first elongate pin  70  and the second elongate pin  72  each extend through and beyond the first pin link plate  54  and receive a pin roller  66  and  68 , respectively, thereabout captured on each respective pin  70  and  72  for rotation. 
         [0025]    As shown in  FIG. 4 , each roller link plate  50  and  52  includes a pair of cylindrical apertures  47 ,  49  and  51 ,  53 , respectively, sized to receive bushing  62 ,  64  in press-fit and swaged relation therein. Each roller  58  and  60  includes a cylindrical inner bore  63  and  65  sized to receive an outer surface of each bushing  62  and  64 , respectively. Bushing  64  includes an inner bore  69  sized to receive pin  70 , whereas bushing  62  is sized to receive a pin  72  (from an adjacent pin link. Each pin link plate  54  and  56  includes a cylindrical inner bore  55 ,  57  and  59 ,  61  sized to receive an outer surface of each pin  70  and  72 , respectively, in press-fit relation. Each roller  66  and  68  includes a cylindrical inner bore  71  and  73  sized to receive an outer surface of each bushing  71  and  73 . Pin  72  also passes through a pair of adjacent roller link plates  50  and  52 , in assembly, from an adjacent and subsequent roller link (not shown) provided between pin link plates  54  and  56 . A pair of cylindrical end crimp fittings  74  and  76  are press-fit, or crimped, in assembly onto ends of each pin  70  and  72  by receiving the end of each pin  70  and  72  within a respective cylindrical bore  75  and  77  in each fitting  74  and  76 . A spike is integrally formed in pin link plate  78  configured to pierce and convey an edge of a thermoformable web, or sheet being conveyed by the conveyor and chain rails of this design. 
         [0026]      FIGS. 5 and 6  show an adjacent pair of roller link  46  and pin link  48  of chain  44  assembled together. Rollers  58  and  60  are laterally offset relative to rollers  66  and  68 , which, in assembly within a chain rail, provides resistance to torque on spike  78  when piercing and engaging a thermoformable web. By making pins  70  and  72  longer (relative to bushing  58 ) than is otherwise needed to assembly together adjacent roller links and pin links, such as roller link  46  and pin link  48 , rollers  66  and  68  are provided with a substantial lateral offset relative to rollers  58  and  60 , which provides significant lateral torque resistance when chain  44  is carried within a chain rail and conveying a thermoformable web. 
         [0027]      FIG. 7  illustrates detailed construction features of chain rail  34 . Chain rail  34  is formed from one or more of formed, or bent, and/or welded pieces of metal. According to one construction, chain rail  34  is formed from stainless steel and steel, with thickened portions formed by welding together separate pieces to form a rail return block  96  comprising an elongate flat, rectangular support surface for primary rollers  58 ,  60  of chain  44  (see  FIG. 4 ). Chain rail  24  forms part of chain track assembly  24 . Chain rail  34  comprises two portions  81  and  83  secured together with threaded fasteners  86  and  88 . Fasteners  86  and  88  also support an elongate chain rail block  80  centrally within chain rail  34 , captured between portions  81  and  83 . Grommets  87  and  89  surround the region where each fastener  86  and  88  is recessed into portions  81  and  83 , respective. In the region where the chain rails span a thermoforming machine, such fasteners are recessed, and in other regions the fasteners can have raised heads (as shown in  FIGS. 13 and 14 ). A stepped down cylindrical bushing  90  extends through an aperture in block  80 , and a complementary bushing  92  is received coaxially about a reduced diameter portion of bushing  90 . Bushings  90  and  92  serve to fix block  80  rigidly within rail  34  at a specific location. Block  80  forms an elongate, flat rectangular surface atop which rollers  62  and  64  are seated for rotation as chain  44  translates there above. Block  80  can be constructed from a steel material. 
         [0028]    In addition, bushings  90  and  92 , block  80  and fasteners  86  and  88  of  FIG. 7  trap and secure a steel L-shaped anti-rotation bracket  82  having a flange, or leg  84  that counteracts against rollers  66  and  68 , preventing a tendency for chain  44  to rotate due to lateral inward loads from a thermoformable web pulling spike  78  in an inward direction towards a center of the web. In one case, bracket  82  and chain rail  34  can comprise stainless steel, or some other suitable structural material with strength to counteract such torque on chain  44  by providing spaced-apart reaction surface  94  and bottom surface  91  of leg  84 . A piece of thin spring steel  85  is further captured between bushing  92  and plate, or portion  81  in assembly. Spring steel  85  provides a hardened surface against which pins  70  and  72  of chain  44  slide down the top delivery path  94  and the bottom return path  96 , reducing wear on the inner ends of pins  70  and  72 . Finally, fluid cooling tubes  98  and  100  are welded via periodic apertures  97  and  99  in portion  83  to hold them therein. In one case, tubes  98  and  100  are constructed from stainless steel, or some other suitable corrosion-resistance metal. 
         [0029]      FIG. 8  illustrates the mounting and travel path of chain  44  within chain rail  34 . Chain rail  32  (of  FIG. 2 ) is constructed in mirror image. More particularly, chain rail  34  supports an array of chain sprockets  101 - 106  for rotation, about which chain  44  is circuitously carried. Sprocket  102  is supported by a chain tensioning mechanism to hold chain  44  around such circuitous path. sprocket  103  is driven by a hexagonal drive shaft (and motor in synchronization with the opposite chain rain, driving chain  44  in rotation to move a thermoformable web along chain rail  34  from an entrance end near bracket  108  of chain drive and tension assembly  38  to an exit end near bracket  109  of chain exit end assembly  40 . 
         [0030]      FIG. 9  shows chain rail  34  of  FIG. 8  from a left side, including bracket  108  and chain  44 .  FIG. 10  shows chain rail  34  of  FIG. 8  from a right side, including bracket  109  and chain  44 . 
         [0031]      FIGS. 11-14  show a modified chain rail  134 , similar to chain rail  34  of  FIGS. 1-10 , but including an optional gap-reducing plate  137  that is secured along an inner lip of chain rail  134  in order to force thermoformable web  135  down over spikes  78  on chain  44  (see  FIG. 12 ) for cases where web  135  is made from a relatively thin sheet of material.  FIG. 13  shows such construction near chain exit end assembly  42 , including chain  44 .  FIG. 14  shows the same construction while omitting chain  44  for viewing purposes. Individual spaced-apart and recessed threaded fasteners  136  secure metal plate  137  within chain rail  134 . 
         [0032]    In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise 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.