Method and apparatus for precision slip-forming of complex precast shapes

Abstract

A system and method for the rapid precision forming of complex precast shapes using a slip form table comprising a slip form assembly and a lift master. The slip-form assembly has a replaceable forming face secured to a compressible backing material which is supported by a rigid slip-form. The lift master has a base master cast in the shape of the desired final cast block, with integral cast lift beams. A drive mechanism raises and lowers the base master relative to the slip-form assembly. The table has a leg and tie-down support. The slip form table may support a single block casting operation, or may support multi-stack casting. The lift master and slip-form may be precision concrete castings.

1 . A slip-form table for forming a plurality of a complex precast block, the slip-form table comprising 
 a slip form assembly, such that the slip form assembly presents a void in the shape of the desired precast block, the slip form assembly comprising 
 a replaceable forming face  220 ,  
 a compressible backing material  240 , and  
 a rigid slip-form  210 ;  
   a lift master  400  comprising 
 a base master  370  comprising 
 a top surface representing the desired cross-sectional shape of the precast block, and  
 a plurality of side surfaces that may be lifted at least partially through the slip form assembly, and  
 
 a plurality of lift beams  390 ;  
   a table support means; and    drive mechanism  3700  for the slip form table.    
   
   
       2 . The slip-form table of  claim 1  wherein 
 the drive mechanism is a mechanical drive system.    
   
   
       3 . The slip-form table of  claim 2  wherein 
 the drive mechanism comprises a plurality of threaded rods, such that the rods may be turned in a first direction to lift the slip form assembly, and turned in a second direction to lower the slip form assembly.    
   
   
       4 . The slip-form table of  claim 1  wherein 
 the rigid slip-form structure is made of cast concrete; and    the lift master is made of cast concrete.    
   
   
       5 . The slip-form table of  claim 1  further comprising 
 a plurality of sleeves provided in the lift master;    a plurality of centering studs which pass through the sleeves in the lift master;    a cast block drive mechanism, such that the cast block drive mechanism lowers a plurality of cast blocks in alignment with the centering studs.    
   
   
       6 . The slip-form table of  claim 1  further comprising 
 a temporary support means for supporting a portion of the plurality of cast blocks so that the lowermost cast block may be harvested.    
   
   
       7 . A slip-form table method for forming a plurality of a complex precast block, the method comprising 
 providing a slip form table comprising 
 a slip form assembly, such that the slip form assembly presents a void in the shape of the desired precast block, the slip form assembly comprising 
 a replaceable forming face,  
 a compressible backing material, and  
 a rigid slip-form,  
 
 a lift master, and  
 drive mechanism for the slip form table; and  
   casting a first block with the slip-form table.    
   
   
       8 . The method of  claim 7  further comprising 
 permitting the first block to partially cure;    removing the first block from the slip-form table; and    casting a second block with the slip-form table.    
   
   
       9 . The method of  claim 7  further comprising 
 permitting the first block to partially cure;    lowering the first block;    casting a second block with the slip-form table;    permitting the second block to partially cure;    lowering the second block; and    continuing to sequentially cast, to partially cure, and to lower a plurality of blocks to form a stack of blocks on top of the first block and the second block.    
   
   
       10 . The method of  claim 9  further comprising 
 removing the first block from the bottom of the stack of blocks;    lowering the stack of blocks; and    casting a block on top of the lowered stack of blocks.    
   
   
       11 . The method of  claim 9  further comprising 
 allowing the top block in the stack of blocks to partially cure; and    removing all blocks in the stack of blocks.    
   
   
       12 . The method of  claim 7  wherein providing a slip form table further comprises 
 preparing a monolithic master; and    casting the slip form with the monolithic master.    
   
   
       13 . The method of  claim 12  wherein preparing a monolithic master further comprises 
 forming a block master by 
 allocating the block master into a plurality of chord elements,  
 casting the plurality of chord elements, and  
 assembling the cast plurality of chord elements;  
   providing a slip-form assembly by 
 binding, to each casting face of the block master, a forming face with compressible backup;  
   forming an inner mold for the master block;    forming an outer mold for the master block; and    casting the monolithic master, such that the monolithic master serves as a geometric guide to which subsequent slip-form assemblies can be bound in order to create additional slip form tables.    
   
   
       14 . The method of  claim 13  wherein casting the plurality of chord elements further comprises 
 making a plurality of precision casting forms; and    concrete casting the plurality of chord elements in the plurality of precision casting forms.    
   
   
       15 . The method of  claim 14  wherein forming a master block further comprises 
 casting a plurality of pipe sleeves in the cast plurality of chord elements; and    assembling the cast plurality of chord elements with a plurality of threaded rod pipe clamps placed in the pipe sleeves.    
   
   
       16 . The method of  claim 7  further comprising 
 casting a plurality of slip forms with the monolithic master.    
   
   
       17 . The method of  claim 7  wherein providing a slip form table comprising 
 a lift master further comprises 
 providing a plurality of lift beams, each lift beam comprising 
 a plurality of upwardly facing plinths,  
 at least one exposed rebar attachment element provided in each plinth, and  
 a plurality of biaxial sleeves;  
 
 providing a casting base comprising 
 the plurality of lift beams positioned in an array of casting beams;  
 
 positioning the slip-form over the casting base,  
 filling in with a packable material all voids within the slip-form that are below the tops of the lift beam plinths;  
 tieing reinforcement to the rebar attachment elements; and  
 casting the lift master.  
   
   
   
       18 . The method of  claim 7  further comprising 
 using the slip-form table as a concrete press to stamp architectural patterns in a flat face of the precast block.    
   
   
       19 . The method of  claim 7  further comprising 
 using the slip-form table as a concrete press to stamp a functional feature in a flat face of the precast block.    
   
   
       20 . The method of  claim 7  wherein providing a slip form table further comprises 
 preparing a monolithic master with a precision-cut set of steel plates that are tabbed together and joined to build a full-size master; and    casting the slip form with the monolithic master.