Fixture for holding a preform during a heating process

Abstract

A restraint fixture ( 12 ) is disclosed that includes a preform retention region configured to limit contracting forces applied against a preform ( 10 ) in the preform retention region when the restraint fixture ( 12 ) thermally contracts. In one embodiment, the restraint fixture ( 12 ) comprises a band ( 12 ) having a first surface defining the preform retention region and a first expansion portion ( 26, 28, 29 ) adapted to deform upon application of a force to the band ( 12 ).

1 . A restraint fixture comprising: 
 a band having a central portion having first and second ends, a first finger extending from said first end at a first angle and a second finger extending from said second end at a second angle, said center portion being curved such that said first end lies adjacent to said second end, and said first finger being connected to said second finger.    
   
   
       2 . The restraint fixture of  claim 1  wherein said first angle is equal to said second angle.  
   
   
       3 . The restraint fixture of  claim 1  wherein said first and second angles are selected such that said first finger contacts said second finger when said first end lies adjacent to said second end.  
   
   
       4 . The restraint fixture of  claim 1  including a connector connecting said first finger to said second finger at a location spaced from said central portion first and second ends.  
   
   
       5 . The restraint fixture of  claim 1  wherein said first finger and said second finger comprise integral portions of said band.  
   
   
       6 . The restraint fixture of  claim 1  wherein said first angle is approximately 90 degrees.  
   
   
       7 . The restraint fixture of  claim 1  wherein said central portion defines a substantially circular preform retention region.  
   
   
       8 . The restraint fixture of  claim 1  wherein said first finger is substantially parallel to said second finger.  
   
   
       9 . A restraint fixture comprising: 
 a band having a central portion having first and second ends, a first finger extending from said first end and a second finger extending from said second end, said center portion being curved such that said first end lies adjacent to said second end, said first finger being connected to said second finger;    said band having a first configuration wherein said first finger extends from said first end at a first angle and said second finger extends from said second end at a second angle and a second configuration wherein said first finger extends from said first end at a third angle different than said first angle and said second finger extends from said second end at a fourth angle different from said second angle.    
   
   
       10 . The restraint fixture of  claim 9  wherein said third angle is greater than said first angle and said fourth angle is greater than said second angle.  
   
   
       11 . The restraint fixture of  claim 9  wherein said first finger is connected to said second finger by a fastener spaced from said first end and said second end.  
   
   
       12 . The restraint fixture of  claim 9  wherein said band is shiftable from said first configuration to said second application by an application of radial force against said central portion.  
   
   
       13 . A restraint fixture comprising: 
 a band having a first surface defining a preform retention region, and    a first expansion portion adapted to deform upon application of a force to said band first surface.    
   
   
       14 . The restraint fixture of  claim 13  including a wall having a second surface defining with the band a preform retention region.  
   
   
       15 . The restraint fixture of  claim 14  wherein said preform retention region is ring shaped.  
   
   
       16 . The restraint fixture of  claim 15  wherein said band surrounds said second surface.  
   
   
       17 . The restraint fixture of  claim 13  wherein said band is continuous.  
   
   
       18 . The restraint fixture of  claim 17  wherein said first expansion portion comprises a crimp in said band.  
   
   
       19 . The restraint fixture of  claim 13  wherein said band includes a first end and a second end and a central portion between first end and said second end, said first and second ends comprising said expansion region.  
   
   
       20 . The restraint fixture of  claim 19  wherein said first end includes a projection and said second end includes a recess receiving said projection.  
   
   
       21 . The restraint fixture of  claim 20  wherein said first end comprises a first finger bent at an angle to said central portion.  
   
   
       22 . The restraint fixture of  claim 20  wherein said first end is parallel to said second end.  
   
   
       23 . The restraint fixture of  claim 19  wherein said first surface comprises an inner surface, said band further comprising an outer surface and said first end inner surface overlies said second end outer surface.  
   
   
       24 . The restraint fixture of  claim 23  wherein said first end inner surface slidingly engages said second end outer surface.  
   
   
       25 . The restraint fixture of  claim 23  wherein said first end inner surface comprises a toothed surface, said second end outer surface comprises a toothed surface, and said first toothed surface and second toothed surface are configured to allow said first end inner surface to slide relative to said second end outer surface in a single direction.  
   
   
       26 . The restraint fixture of  claim 22  wherein said first end is connected to said second end at a point spaced from said central portion.  
   
   
       27 . The restraint fixture of  claim 19  including means for securing said first end to said second end.  
   
   
       28 . The restraint fixture of  claim 27  wherein said means for securing said first end to said second end comprise a loop encircling said band.  
   
   
       29 . The restraint fixture of  claim 22  including a connector connecting said first end to said second end.  
   
   
       30 . The restraint fixture of  claim 29  wherein said connector comprises a screw.  
   
   
       31 . The restraint fixture of  claim 29  wherein said connector comprises a loop encircling said first end and said second end.  
   
   
       32 . The restraint fixture of  claim 13  including a second expansion portion adapted to deform upon application of a force to said band.  
   
   
       33 . The restraint fixture of  claim 13  including a separator plate in said preform retention region adapted to separate a first preform in said preform retention region from a second preform in said preform retention region.  
   
   
       34 . The restraint fixture of  claim 14  including a separator plate in said preform retention region adapted to separate a first preform in said preform retention region from a second preform in said preform retention region, wherein said first surface defines a preform outer diameter, said second surface defines a preform inner diameter, and said separation plate including a larger outer diameter than said preform outer diameter and a smaller inner diameter than said preform inner diameter.  
   
   
       35 . A restraint fixture comprising: 
 a band having a first surface defining a preform retention region, and    means for limiting a force exerted by said band on a preform in said preform retention region during a thermal contraction of said band.    
   
   
       36 . The restraint fixture of  claim 35  wherein said band comprises a first end and a second end connected to said first end.  
   
   
       37 . A restraint fixture comprising: 
 a band having first edge and a second edge and an inner surface defining a preform retention region, said band having a first inner diameter at said first edge greater than a second inner diameter at said second edge.    
   
   
       38 . The restraint fixture of  claim 37  wherein said band comprises a first end and a second end connected to said first end.