Metal working – Method of mechanical manufacture – Impeller making
Reexamination Certificate
1998-09-15
2001-04-10
Cuda, I (Department: 3726)
Metal working
Method of mechanical manufacture
Impeller making
C029S889210, C029S432200
Reexamination Certificate
active
06212771
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to duct work used to convey air for heating, ventilating or air conditioning commercial, industrial and residential buildings. More particularly, the invention relates to a method and apparatus for making self-gripping air vanes provided with button-like protuberances which adapt the vanes to be lockingly fastenable to a pair of opposed air turning rails without tools to form a complete air turning assembly.
B. Description of Background Art
Flowing air used to ventilate, heat, or cool buildings is typically routed through a network of interconnected, elongated, straight rectangular cross-section tubes or ducts, which are collectively referred to as duct work. Changes in the orientation or directional bearing of ducts is usually effected by coupling a pair of ducts together with an angled transition section or elbow. These are bent at an angle, typically of 90 degrees, and have rectangular or circular openings for attachment to separate ducts oriented at the particular bend angle with respect to one another.
When air flowing through a duct impacts the side wall of an elbow or transition section disposed perpendicularly to the flow direction, substantial turbulence is created in the flowing air mass, even when the flow velocity is relatively modest. This turbulence impedes air flow, causing an increase in static pressure and pressure loss coefficients, thus necessitating the use of larger blowers that consume increased drive power, to maintain a given air flow rate at the outlet of the elbow section. Moreover, undesirable vibration and noise may be generated within the duct work, if the turbulence is sufficiently great.
For the reasons stated above, ventilation elbows or transition sections are often constructed to include means for minimizing turbulence, usually by encouraging laminar flow within the elbow. Thus, ventilation elbows constructed to minimize turbulence typically employ a plurality of curved, parallel blades or turning vanes spaced apart at regular intervals, to promote laminar air flow where the direction of air flow changes within the elbow. Typical turning vane assemblies use a plurality of curved sheet metal vanes disposed between a pair of flat, parallel metal sheets, often referred to as rails. The assembly is secured within an angled transition section or elbow.
Turning vane assemblies which employ a variety of techniques for fastening turning vanes to rails has been disclosed in the following United States patents:
Steffens, U.S. Pat. No. 2,292,246, Aug. 4, 1942, Duct Turn: Discloses curved double wall non-metallic duct turns or vanes having a metal insert with a tab that fits into slots cut longitudinally inward from the diagonal end wall of a duct shell, the tab having a protruding finger which is bent flush with the diagonal end wall.
Speiser, U.S. Pat. No. 2,826,221, Mar. 11, 1958, Duct Devices: Discloses duct devices that utilize vanes in the shape of a rectangular plate curved to form a partition wall or guide plate having parallel top and bottom horizontal edges and parallel vertical side edges. Both the top edge and bottom edge of each vane have formed therein a pair of vertically disposed cuts, forming at each cut two tongues, for a total of four tabs. This vane construction requires the provision in each plate or rail of a pair of longitudinally disposed channels or grooves having a V-shaped transverse cross-section. The grooves are formed by downwardly converging walls intersecting on fold line. Each groove or channel has formed therein a plurality of longitudinally spaced apart obliquely disposed slots to receive a pair of tongues, which must be peened over in opposite directions flush with the bottom walls of the V-shaped groove to retain a vane in position between the rails.
Gracer, U.S. Pat. No. 2,861,597, Nov. 25, 1958, Air Guide Device: Discloses single and double wall turning vanes secured in slots formed in the bottoms of dimples protruding inward from rails, by deforming lateral edge walls of the vanes protruding outwards through the slots.
Perlin, U.S. Pat. No. 2,884,956, May 5, 1959, Air Guide Device: Discloses flanged, slotted cup-shaped members inserted through holes formed in a pair of opposed side plates, to secure between the side plates turning blades positioned in the slots.
Gracer, U.S. Pat. No. 2,959,195, Nov. 8, 1960, Air Guide Device: Discloses an air turning assembly having a plurality of curved, rectangular plan view turning vanes or blades that are secured to a pair of rails by crimping opposite lateral edges of the blades protruding outwards through slots in inwardly extending protuberances formed in the rails.
Chesser, U.S. Pat. No. 3,050,160, Aug. 21, 1962, Sheet Metal Connection And Method For Effecting Same: Discloses a sheet metal connection employing a tongue protruding perpendicularly from a first plate inserted through a slot in a second plate, deformations being formed outwards from the plane of the tongue to lock it in place relative to the second plate.
Noll, U.S. Pat. No. 3,075,450, Jan. 29, 1963, Cap Assembly: Discloses a hollow tubular cap assembly having the shape of the frustrum of a cone, connectable to a cylindrical tube by extending flexible straps.
Bohannon, U.S. Pat. No. 3,144,204, Aug. 11, 1964, Centrifugal Blower Wheel: Discloses a centrifugal blower wheel having double-wall, air-foil shaped blades having a plurality of tabs protruding from opposite straight side walls thereof, the tabs on the two walls of each blade being inserted into first and second groups of slots provided through front and rear circular end plates, and bent over to retain the blades in place.
Olmsted, et al., U.S. Pat. No. 3,224,668, Dec. 21, 1965, Blower Wheel Wedged End Blade Mounting: Discloses curved blower wheel blades attachable to annular side rings by a central finger or tongue protruding from opposite short lateral edges of the blade. The fingers are bent into a V-shape, inserted into semi-circular or triangular-shaped holes through the side rings, and bent over to retain the blades in the rings.
Jacobsen, U.S. Pat. No. 3,381,713, May 7, 1968, Turning Vane And Rail Construction: Discloses double-wall, airfoil-shaped turning vanes having formed in the inner side of one wall a pair of cylindrically-shaped passageways disposed perpendicularly inwards from the outer lateral edge of the wall. Headed pins or nails are driven through holes provided in a pair of parallel side rails into the passageways, to secure the vanes to the rails.
Harper, U.S. Pat. No. 3,405,737, Oct. 15, 1968, Duct Device: Discloses double wall vanes secured in slots cut in inwardly protruding depressions in opposed side rails.
Hinden, U.S. Pat. No. 3,494,379, Feb. 10, 1970, Air Turning Assembly And Mounting Rail: Discloses an air turning assembly which employs turning vanes formed of glass fiber impregnated with a polymer and inserted through curved apertures or sockets punched in U-cross section rails. The sockets are outlined by outwardly deflected, spaced tabs or shoulder portions which are compressed by a cam lock against the protruding portion of a vane, thereby securing the vane to the rail.
Hinden, U.S. Pat. No. 3,602,262, Aug. 31, 1971, Air Turning Assembly: Discloses an air turning assembly utilizing fibrous, compressible vane members secured to a pair of parallel rails between the sides of a U-shaped clamp protruding inward from a rail and secured thereto.
Myers, U.S. Pat. No. 4,467,829, Aug. 28, 1984, Turning Vane Rail: Discloses a rail for mounting sheet metal turning vanes that includes a sheet and integral vane guides extending generally perpendicularly away from the plane of the sheet. Each vane guide is a plate slit from the sheet except for one edge along which the plate is bent. The plate is adapted to be positioned adjacent to a wall of the vane. An access aperture, partially located in the sheet and partially located in the plate is adapted to allow access to a portion of the vane wall for contact by a striking tool. A blow from the tool splits th
Ellis Stanley J.
Siiter Donald H.
Chapin William L.
Cuda I
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