Patent Publication Number: US-11644045-B2

Title: Method of manufacturing a fan assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/870,351, filed May 8, 2020, now U.S. Pat. No. 11,193,495, which is a continuation of U.S. patent application Ser. No. 16/185,198, filed Nov. 9, 2018, now U.S. Pat. No. 10,670,036, which is a continuation of U.S. patent application Ser. No. 14/517,212, filed Oct. 17, 2014, now U.S. Pat. No. 10,125,784, which is a continuation of U.S. patent application Ser. No. 13/022,250, filed Feb. 7, 2011, now U.S. Pat. No. 8,881,396, which are incorporated herein by reference. 
    
    
     FIELD 
     The field relates to fans and, more particularly, to fan assemblies for handling airflow. 
     BACKGROUND 
     Centrifugal or forward curved blower wheels may generally comprise a plurality of blades arranged in the form of a cylinder around a solid, central hub disc. During manufacture of a centrifugal blower wheel, a stamping press may be used to form the plurality of blades from a metal sheet. The sheet is gathered between the ends of adjacent blades to reduce the distance between the blades. The sheet, with the material gathered between the blades, is then shaped into a cylinder about the solid, central hub disc. Because the blades are stamped from a single metal sheet, the number of blades and the chords of the blades are limited by the size of the blades and the size of the sheet. 
     The solid, central hub disc of the centrifugal blower wheel may be formed by stamping a pair of discs from respective rectangular pieces of sheet metal, removing the scrap material for recycling, and joining the discs together. A centrifugal blower wheel may also have one or more end rings deformed onto ends of the plurality of blades to fix the blades in the cylindrical arrangement about the central hub disc. Like the central hub disc, the end rings may be formed by stamping circular rings from rectangular pieces of sheet metal and removing the scrap material for recycling. Stamping the one or more end rings generates additional scrap because each end ring has a central opening formed by removing a circular disc from the center of the end ring. In one approach, the scrap material removed from an end ring to form the central opening can be used as a solid, central hub disc for the centrifugal blower wheel. Although scrap material produced during manufacture of the centrifugal blower wheel may be recycled, the value of the recycled material may not compensate for the costs incurred in cutting, storing, and handling the scrap material. 
     Mixed flow fans, backward inclined wheels, backward curved wheels, and other centrifugal wheels may have a back disc and an end ring that are both stamped from rectangular pieces of metal, like the central hub disc and end ring(s) of centrifugal blower wheels. Because the back disc and the end ring have a generally circular shape, stamping the circular shapes from rectangular pieces of sheet metal produces scrap in the form of the corner portions of the sheet metal and a circular disc from the center of the end ring. Similarly, traditional approaches for producing a venturi or orifice for a fan assembly or a fan housing include stamping a generally ring-shaped orifice from a rectangular piece of metal. Even if the scrap circular disc from the end ring or orifice is used to produce a back disc, the corner portions of the sheet located outside of the end ring or orifice would still constitute a large amount of scrap material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a fan assembly; 
         FIG.  2    is a flow diagram of a method of manufacturing the fan assembly of  FIG.  1   . 
         FIG.  3    is a perspective view of the fan assembly of  FIG.  1    with all but two fan blades removed; 
         FIG.  4    is an exploded perspective view of a hub assembly of the fan assembly of  FIG.  1   ; 
         FIG.  5    is a perspective view of a fan blade of the fan assembly of  FIG.  1   ; 
         FIG.  6    is a side elevational view of the fan blade of  FIG.  5   ; 
         FIG.  7    is an exploded perspective view of another fan assembly with only one blade shown for clarity; 
         FIG.  8    is a flow diagram of a method of producing parts of fan assemblies and other components; 
         FIGS.  9 - 13    are perspective views of a ring forming sub-method of the method of  FIG.  8   ; 
         FIGS.  13 A and  13 B  are perspective views of rings formed using the sub-method of  FIGS.  9 - 13   ; 
         FIG.  14    is a top plan view of an orifice; 
         FIG.  15    is a side elevational view of the orifice of  FIG.  14   ; and 
         FIG.  16    is a perspective view of another fan assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In one aspect, a method is provided that minimizes the amount of scrap material produced during manufacture of blower wheel or fan assemblies and related components. Rather than stamp circular parts from rectangular sheets of metal, as in traditional approaches, a narrow strip of material is advanced from a coil and bent along a longitudinal edge of the strip to form a helix. An open annular member is cut from the helix and trimmed as needed before the ends of the open annular member are joined together to form a rigid, annular member. The rigid annular member may be used in place of traditional orifices and fan assembly end rings, to name a few applications. Further, by joining the rigid, annular member with one or more hub strips to produce a hub assembly, the rigid annular member may be used in place of central or end discs of traditional fan assemblies. 
     In another approach, a fan assembly is provided that minimizes the amount of scrap material produced during manufacture of the fan assembly. More specifically, the fan assembly does not utilize a solid disc traditionally used as a center or end disc for blower wheels, mixed flow fans, or other centrifugal air moving devices. Instead, the fan assembly has a hub assembly comprising a hub ring and one or more hub strips. Each hub strip has an attachment portion connected to the hub ring and a body portion extending radially inward from the attachment portion. The one or more hub strips are configured to connect directly or indirectly to a motive source, such as an electric motor, a diesel or gasoline engine, or a turbine, using known mechanical linkages. In one approach, the one or more hub strips are connected to a hub that is fixed to a driveshaft of an electric motor. In another approach, the one or more hub strips have a mounting point or feature for attachment to a shaft or clamp. As is apparent, the hub assembly transmits rotation from the motive source to the fan assembly without the use of a solid disc, as in traditional fan assemblies. 
     Turning to the Figures,  FIG.  1    illustrates a fan assembly  10  that produces a minimal amount of scrap material during production. The fan assembly  10  has a hub  12  for engaging a motor drive shaft (not shown) and transmitting rotation of the drive shaft to the fan assembly  10  such that the fan assembly  10  rotates about an axis of rotation  14 . The hub  12  is part of a hub assembly  16  that includes the hub  12 , one or more hub strips  18 ,  20 , and a hub ring  22 . The hub strips  18 ,  20  connect the hub  12  to the hub ring  22 . In an alternative embodiment, the hub  12  is integrally formed with the hub strips  18 ,  20 . 
     The hub ring  22  has a plurality of attachment points, such as slots  24 , for engaging a plurality of fan blades  26 . Each fan blade  26  extends between a pair of end rings  28 ,  30  and through an associated slot  24  in the hub ring  22 . The hub ring  22  and end rings  28 ,  30  are each formed from an elongate member, such as a strip of material, bent into an annular configuration with respective line welds  23 ,  25 ,  27  fixing the rings  22 ,  28 ,  30  in their annular configuration, as will be discussed in greater detail below. The hub strips  18 ,  20 , hub ring  22 , and end rings  28 ,  30  may be formed from steel, aluminum, or galvanized steel, among other materials. In alternative approaches, the hub ring  22  and the end rings  28 ,  30  may be fixed in an annular configuration without line welds  23 ,  25 ,  27 , such as by features integral to the rings, spot welding, parent metal fastening, or mechanical fasteners. 
     In one approach, each fan blade  26  has a pair of tabs  32 ,  34  extending through respective slots  36 ,  38  in the end rings  28 ,  30 . The tabs  32 ,  34  are bent downward against the end rings  28 ,  30  to fix the blades  26  to the end rings  28 ,  30 . In alternative embodiments, the fan assembly  10  may be a single-inlet type fan assembly with a hub ring  22  and only one end ring  28 . Alternative embodiments may also include attachment points such as rivets or welds that connect the blades  26  to the hub ring  22  and end ring(s)  28  (and  30 ) without the use of tabs or slots. For example, a Fergas peening process may be used to connect the blades  26  to the end ring(s)  28  (and  30 ). 
       FIG.  2    illustrates a method  41  of manufacturing the fan assembly  10  while producing a minimal amount of scrap material. The method  41  includes producing the hub assembly  16  and the end rings  28 ,  30  at step  43 . For some embodiments of the fan assembly  10 , such as a single-inlet blower wheel, only one end ring will be produced. The plurality of blades  26  are manufactured at step  45  with a profile that allows the fan assembly  10  to flow air more efficiently, as will be discussed in greater detail below. The hub assembly  16 , end rings  28 ,  30 , and blades  26  are then assembled at step  47  to produce the fan assembly  10 . 
     Turning to further details of the fan assembly  10 ,  FIG.  3    illustrates the fan assembly  10  with all but two blades  26 A,  26 B removed to show the positioning of the hub assembly  16  between the end rings  28 ,  30 . One of the blades illustrated, blade  26 A, extends between the end rings  28 ,  30  with tabs  32 A,  34 A extending through respective slots  36 A,  38 A. Blade  26 B is connected to the hub ring  22  and the end rings  28 ,  30  by advancing a tab  34 B through slot  24 B in the hub ring  22  until the tab  34 B passes through slot  38 B in the end ring  30 . A tab  32 B of the blade  26 B is then advanced through a slot  36 B in the end ring  28  before the tabs  32 B,  34 B are bent downward against the end rings  28 ,  30  to fix the blade  26 B to the end rings  28 ,  30 . To fix the blade  26 B to the hub ring  22 , an embossing process forms ridges (not shown) in the blade  26 B along paths  42 ,  44  on either side of hub ring  22  to restrict the hub ring  22  from sliding along the blade  26 B. A similar procedure may be performed to install the remaining blades  26  of the fan assembly  10 . 
     In an alternative approach, each slot  24  of the hub ring  22  extends all the way to an outer edge  46  of the hub ring  22 . With this configuration, the blade  26 B may be connected to the hub assembly  16  and the end rings  28 ,  30  by passing a center portion  48  of the blade  26 B through the slot  24 B in a radially inward direction toward the axis  14 . The blade  26 B is then manipulated to advance tabs  32 B,  34 B through respective slots  36 B,  38 B before the blade  26 B is secured to the hub ring  22  and the end rings  28 ,  30  as described above. 
     As shown in  FIG.  3   , the hub strips  18 ,  20  include attachment portions  56 A,  56 B and  58 A,  58 B, respectively. With reference to the attachment portion  56 A, the attachment portion  56 A includes tabs  60 ,  62  that are welded to the hub ring  22 . The tabs of the hub assembly  16  are sized to fit between the slots  24 . Although the attachment portions  56 A,  56 B,  58 A,  58 B are illustrated with tabs for welding to the hub ring  52 , the attachment portions  56 A,  56 B,  58 A,  58 B may connect to the hub ring  22  using any number of approaches, including but not limited to nuts and bolts, rivets, spot welds, line welds, and parent metal fastening. 
     Turning to  FIG.  4   , an exploded view of the hub assembly  16  is illustrated. The hub  12  has a through bore  80  aligned with the axis of rotation  14  for receiving a motor drive shaft (not shown) and an opening  82  for receiving a set screw (not shown) which secures the hub  12  to the motor drive shaft. The hub  12  may be cold headed from wire, machined from 12L14 steel bar stock, or any other acceptable manufacturing process and/or material. The hub  12  is generally received within openings  84 ,  86  of the hub strips  18 ,  20  and is connected to the hub strips  18 ,  20  using, for example, an orbital press, swedging, and/or staking. 
     The hub strip  18  includes a body portion  88  extending between the attachment portions  56 A,  56 B. In the illustrated embodiment, the hub  12  is a separate component from the hub strips  18 ,  20  and the hub strips  18 ,  20  have features for aligning the hub strips  18 ,  20  and receiving the hub  12 . More specifically, the body portion  88  includes a hub mounting portion  90  having a concave seat  92  that tapers downward toward a circular flat  94  extending about the opening  84 . Similarly, the hub strip  20  has a body portion  96  extending between attachment portions  58 A,  58 B. The body portion  96  has a hub mounting portion  98  with a concave seat  100  and a circular flat  102  that are complimentary to the seat  92  and the flat  94  of the hub strip  18  such that the hub mounting portions  90 ,  98  may nest together when the hub assembly  16  is assembled. Alternatively, the hub mounting portions  90 ,  98  may be flat and lack seats  92 ,  100  or other structures that nest together. 
     The hub ring  22  defines a central opening  110  having a center point  112  aligned with the axis  14 , as shown in  FIG.  4   . The hub ring  22  has an outer radius  114  and an inner radius  116  that define a width  113  of the hub ring  22 . When the hub strips  18 ,  20  are connected to the hub ring  22 , the body portions  88 ,  96  extend across the central opening  110  and provide a rigid connection between the hub  12  and the hub ring  22 . 
     As shown in  FIG.  5   , the blade  26  has a body portion  130  with a pair of opposed end portions  132 ,  134 . The blade  26  has an outlet portion  140  with an outlet angle and an inlet portion  142  with an inlet angle. Preferably, the outlet angle is different than the inlet angle, although the outlet portion  140  and the inlet portion  142  may have similar angles. In the illustrated embodiment, the blade  26  has a compound radius design, with the outlet portion  140  and inlet portion  142  each having a different radius of curvature, although other embodiments may have a similar radius of curvature for portions  140 ,  142 . The blade  26  moves more air than traditional fan blade designs for a given blade size, which allows a fan assembly utilizing the blade  26  to have fewer blades while flowing the same amount of air as traditional fan assemblies. Conversely, a fan assembly utilizing the blade  26  and having the same number of blades as a traditional fan assembly will flow a greater amount of air and generate a higher static pressure than a traditional fan assembly. 
     The blade  26  may be formed using, for example, roll forming or stamping. To control consistency during mass production, the blade  26  may be embossed after forming to limit spring-back of the blade  26  and provide more consistent tolerances of the blade  26 . Further, the blade  26  may be made from a number of materials, including but not limited to galvanized steel, aluminum, and plastic. For plastic blades, a rigid or semi-rigid plastic may be chosen, such as polypropylene. A plastic blade may be molded or extruded. 
     As shown in  FIG.  6   , the blade  26  extends between an outlet tip  150  and an inlet tip  152  that travel along an outer diameter  154  and inner diameter  156 , respectively, as the fan assembly  10  rotates. In one approach, the outer diameter  154  is in the range of approximately 9.66 inches to approximately 11.80 inches, preferably 10.73 inches. A ratio of the outer diameter  154  to the inner diameter  156  is preferably within the following range: 
     
       
         
           
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     In other approaches, the diameters  154 ,  156  may be increased or decreased with corresponding adjustments to the other dimensions of the blade  26  to accommodate different applications of the blade  26 . The outlet portion  140  of the blade  26  extends inward from the outlet tip  150  along a plane  158 . The plane  158  is oriented at an angle  160  relative to the outer diameter  154 , the angle  160  being in the range of approximately 100° to approximately 180°, preferably 160°. The outlet portion  140  converges with a plane  164  that extends parallel to a plane  174 . A blade camber distance  168  separates the plane  164  from the plane  174 , the blade camber distance  168  being in the range of approximately 0.150 inches to approximately 0.375 inches, preferably 0.287 inches. The plane  174  extends a chord distance  176  between the tips  150 ,  152 . The chord distance  176  is in the range of approximately 0.890 inches to approximately 1.088 inches, preferably approximately 0.989 inches. A ratio of the chord distance  176  to the blade camber distance  168  is preferably within the following range: 
     
       
         
           
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     Given this chord/camber ratio and the chord distance  176 , the blade camber distance  168  for a desired chord/camber ratio may be calculated by dividing the chord distance  176  by the desired chord/camber ratio. A plane  180  generally extends along a radius of the diameters  154 ,  156 , and intersects blade tip  150 . The plane  174  is oriented at a blade setting angle  166  relative to the plane  180 . The blade setting angle  166  is in the range of approximately 10° to approximately 40°, preferably approximately 27.4°. An inlet portion  142  extends away from the plane  164  and converges with a plane  170  at the inlet tip  152 . The plane  170  is oriented at an angle  172  relative to the inner diameter  156 , the angle  172  being in the range of approximately 45° to approximately 70°, preferably 63°. Given the outer diameter  154 , the ratio of the outer diameter  154  to the inner diameter  156 , and the blade setting angle  166 , the chord distance  176  can be determined using the following equation: 
     
       
         
           
             
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     Another embodiment of a fan assembly  300  having a hub assembly  302  is shown in  FIG.  7   . The fan assembly  300  is similar to the fan assembly  10 , with the exception that the hub strips  304 ,  306  have attachment portions  308 A,  308 B and  310 A,  310 B which lack tabs for engaging a hub ring  312 . Instead, the attachment portions  308 A,  308 B and  310 A,  310 B have slots  313 ,  314  which align with slots  316  of the hub ring  312 . To secure the hub strips  304 ,  306  to the hub ring  312 , each blade  318  is passed through one of the plurality of slots  313  (or  314 ) and one of the plurality of slots  316  before ridges are embossed in the blade  318  to fix the hub strip  304  (or  306 ) and the hub ring  312  between the ridges, as discussed above with respect to fan assembly  10 . The hub strips  304 ,  306  may alternatively be connected to the hub ring  312  using welds, rivets, or other approaches. Further, slots  313  (or  314 ) and the slots  316  may extend to an outer edge  319  of the hub ring  316  to accommodate radial insertion of the blades  318 , as discussed above. 
       FIG.  8    illustrates a method  400  of producing a product, such as the end rings  28 ,  30  or the hub assemblies  16 ,  302  of the fan assemblies  10 ,  300 , while generating a minimal amount of scrap material. The method  400  comprises a ring forming sub-method  402 , explained with reference to  FIGS.  9 - 13 B , and a finishing sub-method  404 , explained with reference to  FIGS.  1  and  14 - 16   . Although the method  400  is described in steps, it will be appreciated that the steps may be modified, combined, removed, or performed in a different order than the order presented. Further, additional or fewer actions may be performed at each step without departing from the teachings of this disclosure. If the method  400  is used to produce an orifice, end ring, or hub assembly, the method  400  provides a material yield of nearly 100%, which is at least a 33% improvement over traditional processes. 
     In one approach, the method  400  utilizes a ring forming device  500 , shown in  FIG.  9   , to shape a raw material into a ring during the ring forming sub-method  402 . For example, the raw material may be a strip of material  540  (see  FIG.  10   ) such as aluminum, steel, galvanized steel, coated steel, or other materials which can be advanced from a coil of the raw material. In the illustrated embodiment, the ring forming device  500  is connected to a roll forming machine  502  to utilize rotation of a shaft  504  of the roll forming machine  502 . In another embodiment (not shown), the ring forming device  500  may be a stand-alone device with a dedicated drive motor. Returning to  FIG.  9   , the strip of material  540  is advanced between feed rollers  506 ,  508 ,  510  and into slots  512 ,  514  on a pair of forming rollers  516 ,  518 . The feed rollers  506 ,  508  and forming rollers  516 ,  518  are driven to advance the strip of material  540  through the ring forming device  500 . More specifically, a powered roller drives the feed rollers  506 ,  508 . Similarly, a drive shaft  504  rotates a drive gear  520  and the roller  516  which is attached to the drive gear  520 . Rotation of the drive gear  520  rotates follower gear  522  and the roller  518  connected thereto in an opposite direction. A pair of arms  524 ,  526  hold the rollers  516 ,  518  relative to one another, with plates  528 ,  530  rigidly fixing the arms  524 ,  526  together. 
     The ring forming sub-method  402  begins at step  406  where a raw material and dimensions of the raw material are chosen. In the illustrated approach, the raw material is the strip of material  540  having a generally flat cross-section with a width  542  and a thickness  544  (see  FIG.  10   ). At step  408  in  FIG.  8   , the strip of material  540  is advanced into the ring forming device  500 , as shown in  FIG.  10   . The strip of material  540  has a center line  546  extending between central axes  548 ,  550  of the forming rollers  516 ,  518  as the strip of material  540  is fed through the rollers  506 ,  508 ,  510 . To adjust the radius of the ring produced from the strip of material  540 , the ring forming device  500  includes a radius adjustment device  552  that adjusts the position of the arms  524 ,  526  above a base  554  of the device  500 . The radius adjustment device  552  comprises a threaded bolt (not shown) and a nut  551  engaged with threads of the bolt. The plate  528  rests upon the threaded bolt such that rotation of the nut  551  advances/retracts the bolt relative to the base  554  and elevates/lowers the arms  524 ,  526  a distance  556  above the base  554 . 
     Adjusting the distance  556  between the arms  524 ,  526  and the base  554  rotates the arms  524 ,  526  and the roller  518  about the central axis  548  of the roller  516 . By adjusting the position of the arms  524 ,  526 , the angle at which the roller  518  bends the strip of material  540  can be adjusted. More specifically, rotating the arms  524 ,  526  counterclockwise about the axis  548  decreases the radius of the ring produced from ring forming device  500 . Conversely, rotating the arms  524 ,  526  clockwise about the axis  548  increases the radius of the ring. 
     With reference to  FIG.  10   , rotating the arms  524 ,  526  tends to bring the central axis  550  of the roller  518  closer to the centerline  546  of the strip of material  540 . Stated differently, rotating the arms  524 ,  526  counterclockwise about the axis  548  moves the roller  518 , decreases distance  558 , and increases distances  566 ,  568 . This causes the strip of material  540  to strike the roller  518 , in particular, a bottom surface  519 A of the slot  514 , closer to the equator of the roller  518  and bend at a relatively sharp angle away from the roller  518 . Conversely, rotating the arms  524 ,  526  clockwise increases the distance  558  and decreases the distances  566 ,  568 . This causes the strip of material  540  to strike the bottom surface  519 A of the slot  514  of the roller  518  farther from the equator of the roller  518  and bend at a relatively softer angle away from the roller  518 . 
     In the illustrated embodiment, the rollers  506 ,  508 ,  510 ,  516  of the ring forming device  500  do not change position as the radius adjustment device  552  is used to adjust the position of the arms  524 ,  526 . Given the stationary nature of the rollers  510 ,  516 , rotating the arms  524 ,  526  does not change the distances  560 ,  563 ,  564 . In alternative embodiments of the ring forming device  500 , the positions of one or more of the rollers  506 ,  508 ,  510 ,  516  may be adjustable in combination with, or in place of, movement of the roller  518 . 
     In addition to the radius adjustment device  552 , slot depths  570 ,  572 ,  574 ,  576 ,  578  of the feed rollers  506 ,  508 ,  510 ,  516 ,  518  also control the radius of the ring produced from the strip of material  540 , as shown in  FIG.  10   . The slot depths  570 ,  572 ,  574 ,  576 ,  578  are selected to position a predetermined amount of the width  542  of the strip of material  540  within the slots  512 ,  514  of the rollers  516 ,  518 . Further, the slots of the rollers  506 ,  508 ,  510 ,  516 ,  518  are sized to accommodate the thickness  544  of the strip of material  540 . In one approach, the width  542  of the strip of material  540  received within the slot  514  as the material  540  passes through the roller  518  is in the range of between approximately 20% and 90% of the total width  542 . This engagement between the roller  518 , in particular, two side surfaces  519 B,  519 C of the slot  514 , and the strip of material  540  tends to limit flexing of the strip of material  540  as the strip of material  540  advances through the ring forming device  500 , as shown in  FIG.  13   . 
     At step  410  in  FIG.  8   , the strip of material  540  is advanced toward the slotted rollers  516 ,  518  until a leading end portion  590  contacts the roller  518 , in particular, the bottom surface  519 A of the slot  514 , and curls upward, as shown in  FIGS.  11  and  13   . The leading end portion  590  may include a rounded nose  592  and a flat  594  for contacting the roller  518  and directing the leading end portion  590  upward. In this manner, the roller  518  acts as a curling shoe to curl the strip of material  540 . Curling the strip of material  540  compresses a radially inner portion  596  of the strip of material  540  while tensioning a radially outer portion  598  located across the center line  546 . 
     During step  410  in  FIG.  8   , the strip of material  540  continues to be advanced into the ring forming device  500  until the leading end portion  590  makes a complete loop and the strip of material  540  forms a ring  610 , as shown in  FIG.  12   . The ring  610  can extend in a generally annular configuration for greater or less than 360° as desired for a particular application. The ring  610  has inner and outer radii  614 ,  616  and a ring width  613  defined between the inner and outer radii  614 ,  616 . The process of bending the strip of material  540  into the ring  610  may create a wave in the ring  610  along the ring width  613 . To minimize the waviness of the ring  610 , the dimensions of the strip of material  540  may be selected to provide a predetermined ratio of the inner radius  614  to the width  542  (see  FIG.  10   ). For example, the ratio of the inner radius  614  to the width  542  may be in the range of approximately 0.5:1 to approximately 46:1. Further, the dimensions of the strip of material  540  may be selected to provide a predetermined ratio of the outer radius  616  to the width  542 . For example, the ratio of the outer radius  616  to the width  542  may be in the range of approximately 2.5:1 to approximately 48:1. These ratios can be adjusted to accommodate different thicknesses  544  of the strip of material  540 , as well as different materials, chemistries, and material treatments. The following table presents exemplary ratios for several products having a ten-inch outer diameter: 
     
       
         
           
               
               
               
             
               
                   
               
               
                   
                 Ratio of Ring Inner 
                 Ratio of Ring Outer 
               
               
                 Type of Product 
                 Radius to Strip Width 
                 Radius to Strip Width 
               
               
                   
               
             
            
               
                 Forward Curved Wheel 
                 18:1  
                 20:1  
               
               
                 Forward Curved Strip Wheel 
                 38:1  
                 40:1  
               
               
                 Backward Inclined Wheel 
                 0.5:1   
                 2.5:1   
               
               
                 Backward Curved Wheel 
                 0.5:1   
                 2.5:1   
               
               
                 Mixed Flow Wheel 
                 8:1 
                 10:1  
               
               
                 Orifices and Inlet Rings 
                 3:1 
                 5:1 
               
               
                   
               
            
           
         
       
     
     Continued advancing of the strip of material  540  into the ring forming device  500  produces a helix  620  at step  410 , as shown in  FIG.  13   . The helix  620  wraps around a center axis  612  and is directed to the side of the ring forming device  500 . At step  412  in  FIG.  8   , the ring  610  is cut from the helix  620  and at step  414 , mating ends of the ring  610  are formed. Steps  412  and  414  may be combined such that cutting the ring  610  from the helix  620  forms one or both of the mating ends of the ring  610 . For example, as indicated in  FIG.  13   , the ring  610  may be cut from the helix  620  by creating bevel cuts along paths  622 ,  624  so that ends  626 ,  628  of the ring  610  can be flush with one another after the ring  610  is removed from the helix  620 . Other approaches may be used to remove the ring  610  from the helix  620 , such as using a radial cut. In one approach, the strip of material  540  continues to be advanced into the ring forming device  500  to generate a larger helix  620  with several rings  610  before the helix  620  is separated from the strip of material  540 . The rings  610  may then be cut from the helix  620 . 
     At step  416  in  FIG.  8   , the mating ends  626 ,  628  are optionally joined together using, for example, a YAG laser-welding procedure. As shown in  FIG.  13 A , the ring  610  has mating ends  626 ,  628  joined together at a weld  630 . Joining the mating ends  626 ,  628  of the ring holds the ring  610  in an annular configuration and provides a rigid structure for subsequent processes, such as for connecting the fan blades  26  to the ring  610 . For some applications of the ring  610 , such as an orifice for a blower housing assembly, the mating ends  626 ,  628  need not be joined together. 
     The mating ends of the ring may be joined together using alternative approaches, such as spot welding, parent metal fastening, or mechanical fasteners. For an approach such as spot welding, the ring  610  may be longer than 360° so that there are overlapping portions of the ring  610  that can be spot welded together. For example, the ring  610  may have end portions  632 ,  634  that overlap and are joined at a spot weld  636 , as shown in  FIG.  13 B . If the ring  610  with overlapping portions  632 ,  634  is used in a fan assembly application, such as for the hub ring  22  of the fan assembly  10  (see  FIG.  1   ), it is preferred to utilize at least one other ring  610  with overlapping portions in the fan assembly  10 , such as the end rings  28  and  30 , to evenly balance the fan assembly  10 . More specifically, the overlapping portions  632 ,  634  of the rings  610  are spaced evenly around the fan assembly  10 , i.e., the overlapping portions of the hub ring  22  and end rings  28 ,  30  would each be separated by approximately 120° from one another around the circular profile of the fan assembly  10 . Weights or other corrective measures could be then applied to the fan assembly  10  to balance the fan assembly  10  after the blades  26  have been installed. 
     At this point, the completed ring  610  enters the finishing sub-method  404  of  FIG.  8   , which will be described in greater detail with respect to  FIGS.  1  and  14 - 16   . If the final product is to be a venturi or orifice at step  418  in  FIG.  8   , the shape of the orifice may be formed at step  420 . The orifice can be utilized on mixed flow fans, blower housing inlets, backward inclined centrifugal fan assemblies, and backward curved centrifugal fan assemblies, to name a few applications. In one approach the ring  610  can be formed into an orifice  700 , shown in  FIGS.  14  and  15   , at step  420  in  FIG.  8   . The ring  610  can be formed into an orifice  700  using spinning or forming in a die. The orifice  700  includes ends  702 ,  704  that correspond to the ends  626 ,  628  of the ring  610  in  FIG.  13   . The ends  702 ,  704  are joined at a weld  706 , which was applied at step  416  in  FIG.  8    before the ring  610  entered the finishing sub-method  404 . The orifice  700  includes a neck portion  708  defining an inlet  710  and a flange portion  712  for connecting to the associated fan assembly, blower housing structure, or other component. In another approach, the ring forming device  500  simultaneously bends the strip of material  540  into the ring  610  and forms features of an orifice into the ring  610  such that a substantially complete orifice  700  exits the ring forming device  500 . In this approach, the rollers  506 ,  508 ,  510 ,  516 ,  518  are configured to impart the desired curvature of the orifice  700 , such as the neck portion  708 , as the strip of material  540  is advanced through the ring forming device  500 . The orifice  700  may be made from galvanized steel, aluminized steel, aluminum, or stainless steel, among other materials. 
     If the ring  610  is to become an end ring at step  422  in  FIG.  8   , the ring  610  may be shaped at step  424 . For example, the end ring  28  of the fan assembly  10  in  FIG.  1    may not require additional forming. By contrast, a backward inclined centrifugal fan assembly  800 , as shown in  FIG.  16   , has an end ring  802  with an integral orifice  804  formed using a die press or other forming method at step  424 . The forming of the orifice  804  into the end ring  802  is one example of the shaping that may occur at step  424  in  FIG.  8   . Like the orifice  700 , the end ring  802  has ends  806 ,  808  that correspond to the ends  626 ,  628  of the ring  610 . The ends  806 ,  808  are joined at a weld  810 , or other joining method, which was applied at step  416  in  FIG.  8    before the ring  610  entered the finishing sub-method  404 . 
     At step  426  in  FIG.  8   , attachment points for connecting fan blades to the end ring are added to the end ring. For example, slots may be formed in the end ring if the end ring is similar to the end ring  28  of the fan assembly  10 . For the end ring  802  of the fan assembly  800 , rivets  812  are used to connect a plurality of blades  814  to the end ring  802 . 
     If the ring  610  is to become part of a hub assembly at step  428  in  FIG.  8   , the ring  610  is used as a hub ring and shaped at step  430  if needed. Further, fan blade attachment points may be formed on the hub ring at step  430 . A hub assembly produced at step  428  using the ring  610  may replace a back disc for, among other applications, a forward curved single inlet centrifugal fan assembly, a backward inclined centrifugal fan assembly, a backward curved centrifugal fan assembly, and a mixed flow fan assembly. A centrifugal fan assembly produced using the ring  610  may be any type of centrifugal air moving device having forward curved blades or other blade configurations. Similarly, a hub assembly produced using the ring  610  can replace a central disc for, among other applications, a forward curved double inlet centrifugal fan assembly or an end disc for a forward curved tangential fan assembly. 
     For example, the ring  610  may be used as a hub ring  22  of the fan assembly  10  with a minimal amount of shaping and the addition of slots  24  at step  430 . Similarly, the ring  610  may be used as a hub ring  824  of the fan assembly  800  with minimal shaping and the addition of holes to receive rivets  813  which secure the plurality of blades  814  to the hub ring  824 . As shown in  FIG.  16   , ends  826 ,  828  of the hub ring  824  correspond to ends  626 ,  628  of the end ring  610 . 
     At step  432  in  FIG.  8   , one or more hub strips for joining to the hub ring may be stamped from a coil of material, such as hub strips  18 ,  20  of the fan assembly  10  or the hub strips  820 ,  822  of the fan assembly  800 . At step  433 , the one or more hub strips may be shaped, such as shaping the hub mounting portions  90 ,  98  of the hub strips  18 ,  20  of the fan assembly  10  (see  FIG.  4   ). By contrast, the hub strips  820 ,  822  are illustrated in  FIG.  16    without mating portions, such that shaping the hub strips  820 ,  822  at step  433  is unnecessary. 
     At step  434  in  FIG.  8   , a hub may be connected to the hub strips, such as connecting a hub  823  of the fan assembly  800  to the hub strips  820 ,  822 . For rigidity purposes and/or to influence the resonance frequency of a fan assembly, the hub strips  820 ,  822  may be joined together before the hub strips  820 ,  822  and the hub  823  are connected to the hub ring  824 . The hub strips  820 ,  822  may be joined together using welds, rivets, or other approaches. In some applications of the method  400 , the step  434  is not performed, such as when the hub  823  is integrally formed with one of the hub strips  820 ,  822 . Further, the step  434  may be omitted when a fan assembly does not utilize a hub, such as when the hub strips  820 ,  822  have a mounting point or feature for direct attachment to a shaft or clamp. 
     At step  436  in  FIG.  8   , the attachment portions of the hub strips are connected to the hub ring. For example, the tabs  60 ,  62  of the hub strip  18  (see  FIG.  3   ) are spot welded or joined by some other method to the hub ring  22 . The hub strip  820 , by contrast, has attachment portions  830 ,  832  connected to the hub ring  824  using rivets  834 . 
     Returning to  FIG.  8   , if the ring  610  is to be used for a product other than an orifice, an end ring, or a hub assembly, the ring  610  goes on to subsequent processing at step  438  to produce the desired product. 
     It will be understood that various changes in the details, materials, and arrangements of parts and components which have been herein described and illustrated in order to explain the nature of the fan assembly and method may be made by those skilled in the art within the principle and scope of the fan assembly and method as expressed in the appended claims. Furthermore, while various features have been described with regard to a particular embodiment or a particular approach, it will be appreciated that features described for one embodiment also may be incorporated with the other described embodiments.