Two-piece molded fan

Abstract

A two-piece molded fan assembly is produced having overlapping fan blades using an axial draw technique. The two halves are then removed from the mold and coupled together to form the two-piece fan. By molding the fan as two pieces, a fan blade can be produced that wraps around the outside of the housing and overlaps with each other in a quick and easy manner using a simple mold design. The two pieces are formed such that the a portion of each overlapping blade is formed on both halves of the assembly so that the die casting tool can be removed along a central axis defining the fan assembly without contacting the respective portion of the fan blades, therein greatly simplifying the manufacturing techniques.

What is claimed is:  
     
         1 . A method for forming a fan assembly defined by and capable of spinning about a central axis, said fan assembly having a plurality of circumferentially displaced, radially disposed overlapping fan blades coupled about a central hub, the method comprising comprising: 
 determining a relative positioning plane extending through the plurality of overlapping fan blades and central hub of the fan assembly, said relative positioning plane located such that a front portion of said plurality of overlapping fan blades are located on one side of the relative positioning plane a rear portion of said plurality of overlapping fan blades are located on the opposite side of said relative positioning plane;    die casting said front portion of the two piece fan assembly, said front portion having said first portion of said plurality of overlapping fan blades and a front hub portion and a substantially flat front flat portion, said front flat portion defined by said relative positioning plane;    die casting a rear portion of the two piece fan assembly, said rear portion having said second portion of said plurality of overlapping fan blades and a rear hub portion and a substantially flat rear flat portion, said rear flat portion defined by said relative positioning plane; and    coupling said front portion to said rear portion to form the two-piece fan assembly.    
     
     
         2 . The method of  claim 1 , wherein die casting a front portion and die casting a rear portion comprises: 
 introducing a first quantity of a molten material within said front portion of a die casting tool;    introducing a second quantity of said molten material within said rear portion of said die casting tool; and    cooling said first quantity of cast molten material to form said front portion and cooling said second quantity of cast molten material to form said rear portion.    
     
     
         3 . The method of  claim 1 , wherein said front hub portion has a plurality of bolt holes formed therein and wherein said rear hub portion has a second plurality of holes formed therein.  
     
     
         4 . The method of  claim 2 , wherein coupling said front portion to said rear portion comprises: 
 providing a plurality of bolts, each of said plurality of bolts having a head;    forming a plurality of front bolt holes on said front hub portion in a post-casting step;    forming a second plurality of rear bolt boles on said rear hub portion in a post-casting step;    coupling said front flat portion of said front portion to said rear flat portion of said rear portion;    introducing one of said plurality of bolts through a corresponding one of said plurality of front bolt holes and through a corresponding one of said second plurality of rear bolt holes, wherein at least one of said heads of said plurality of bolts is closely coupled with said front hub portion; and    securing each of said plurality of bolts.    
     
     
         5 . The method of  claim 2 , wherein coupling said front portion to said rear portion comprises: 
 providing a plurality of bolts, each of said plurality of bolts having a head;    forming a plurality of front bolt holes on said front hub portion in a post-casting step;    forming a second plurality of rear bolt boles on said rear hub portion in a post-casting step;    coupling said front flat portion of said front portion to said rear flat portion of said rear portion;    introducing one of said plurality of bolts through a corresponding one of said second plurality of rear bolt holes and through a corresponding one of said plurality of front bolt holes such that at least one of said heads is closely coupled with said rear hub portion; and    securing each of said plurality of bolts.    
     
     
         6 . The method of  claim 4 , wherein securing said plurality of bolts comprises securing each of said plurality of bolts with a corresponding nut, said corresponding nut closely coupled with said rear hub portion.  
     
     
         7 . The method of  claim 5 , wherein securing said plurality of bolts comprises securing each of said plurality of bolts with a corresponding nut, said corresponding nut closely coupled with said front hub portion.  
     
     
         8 . The method of  claim 3 , wherein coupling said front portion to said rear portion comprises: 
 providing a plurality of bolts, each of said plurality of bolts having a head;    coupling said front flat portion of said front portion to said rear flat portion of said rear portion;    introducing one of said plurality of bolts through a corresponding one of said plurality of front bolt holes and through a corresponding one of said second plurality of rear bolt holes, wherein at least one of said heads of said plurality of bolts is closely coupled with said front hub portion; and    securing each of said plurality of bolts.    
     
     
         9 . The method of  claim 3 , wherein coupling said front portion to said rear portion comprises: 
 providing a plurality of bolts, each of said plurality of bolts having a head;    coupling said front flat portion of said front portion to said rear flat portion of said rear portion;    introducing one of said plurality of bolts through a corresponding one of said second plurality of rear bolt holes and through a corresponding one of said plurality of front bolt holes such that at least one of said heads is closely coupled with said rear hub portion; and    securing each of said plurality of bolts.    
     
     
         10 . The method of  claim 8 , wherein securing said plurality of bolts comprises securing each of said plurality of bolts with a corresponding nut, wherein said corresponding nut is closely coupled with said rear hub portion.  
     
     
         11 . The method of  claim 9 , wherein securing said plurality of bolts comprises securing each of said plurality of bolts with a corresponding nut, wherein said corresponding nut is closely coupled with said front hub portion.  
     
     
         12 . A method for die casting a two-piece fan assembly having a plurality of circumferentially displaced, radially disposed overlapping fan blades, said fan assembly capable of rotating about a central axis, the method comprising: 
 determining a relative positioning plane extending through the plurality of overlapping fan blades and central hub of the fan assembly, said relative positioning plane located such that a front portion of said plurality of overlapping fan blades are located on one side of the relative positioning plane a rear portion of said plurality of overlapping fan blades are located on the opposite side of said relative positioning plane;    die casting a front portion and a rear portion of the two piece fan assembly within a die casting tool having a front section and a rear section, wherein said front portion having said first portion of said plurality of overlapping fan blades and a substantially flat front flat portion, said front flat portion defined by said relative positioning plane,    wherein said rear portion having said second portion of said plurality of overlapping fan blades and a substantially flat rear flat portion, said rear flat portion defined by said relative positioning plane;    uncoupling said front section of said die cast tool along said central axis away from said relative positioning plane such that said front section does not contact first portion of said plurality of overlapping blades; and    uncoupling said rear section of said die cast tool along said central axis away from said relative positioning plane such that said rear section does not contact second portion of said plurality of overlapping blades.    
     
     
         13 . The method of  claim 12 , wherein die casting a front portion and die casting a rear portion comprises: 
 introducing a first quantity of a molten material within said front section;    introducing a second quantity of said molten material within said rear section; and    cooling said first quantity of cast molten material to form said front portion and cooling said second quantity of cast molten material to form said rear portion.    
     
     
         14 . The method of  claim 12 , wherein said front hub portion has a plurality of bolt holes formed therein and wherein said rear hub portion has a second plurality of holes formed therein.