Abstract:
A ductmaking apparatus forms a laminate section including a sheet metal layer and a layer of insulation fastened to the sheet metal layer. The layer of insulation is severed from a moving web of insulation by pivoting slicing movement of a knife across the moving web.

Description:
CROSS-REFERENCE OF RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/159,609, filed on Mar. 12, 2009, and herein incorporated by reference in its entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates to apparatus for making ventilation ducts and, more particularly, to apparatus for attaching insulation to ventilation ducts. 
       BACKGROUND OF THE INVENTION 
       [0003]    Ducts are extensively utilized in heating and ventilating systems to distribute heated or cooled air throughout a building structure. These ducts are commonly formed from differing gauges of sheet metal, or the like, in sections of predetermined lengths which are then connected to one another to form a continuous duct system for distributing air. 
         [0004]    It is oftentimes necessary to integrate insulation material with ductwork in order to provide the required thermal characteristics for a given application. Typically, the insulation that is utilized is comprised of a fiberglass material and is commonly packaged as a continuous roll of insulation. Known cutting devices are then employed to unroll a predetermined amount of insulation and effect a severing action in accordance with the specific type, size and shape of ductwork that is intended to be insulated. 
         [0005]    For a variety of reasons, the HVAC industry has often used rubber or neoprene flexible foam insulation in place of or in addition to fiberglass insulation. Unlike fiberglass insulation, foam insulation has significant elasticity and mechanical structure. Because of its elastic structure, the foam insulation has greater mechanical toughness than fiberglass and more strongly resists being cut off by conventional chop or guillotine type shear. Thus, shears presently used for cutting fiberglass insulation and sheet metal can be utilized for cutting foam insulation only by adding structure and power to the shears. However, upgrades to make existing shears sturdier may not be compatible with the machinery in which the shears are housed. Also, stronger shears cost more to build and install, and more powerful shears cost more to operate. It will be readily appreciated that the operational difficulties in obtaining clean, repetitive cuts of the new insulating materials results in reduced productivity and increased labor costs. 
         [0006]    With the forgoing problems and concerns in mind, it is the general object of the present invention to provide an insulation cutoff device, which overcomes the above-described drawbacks. 
       SUMMARY OF THE INVENTION 
       [0007]    According to the present invention, a ductmaking apparatus includes a pivoting knife that is used to cut off a segment of fiberglass or foam insulation from a moving web by slicing, rather than by shearing. The ductmaking apparatus fastens the segment of insulation to a metal sheet to form a laminate section. 
         [0008]    These and other objects, features and advantages of the present invention will become apparent in light of the detailed description of the best mode embodiment thereof, as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a perspective view of an apparatus for assembling insulated duct sections, according to an embodiment of the present invention. 
           [0010]      FIGS. 2-5  are side and end elevation views of an insulation cut-off apparatus performing sequential steps of a method using said apparatus, according to an embodiment of the present invention. 
           [0011]      FIG. 6  is a detail side elevation view showing said insulation cut-off apparatus severing a web of insulation. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0012]    Referring to  FIG. 1 , according to an embodiment of the present invention a sheet of metal is fed from a coil (not shown), and a web of insulation  10  is fed by pinch rollers (not shown) from a roll  11 , through an apparatus  12  for assembling insulated duct sections. In the embodiment shown in  FIG. 1 , the web of insulation is fed above the sheet of metal. The apparatus includes a vertically movable clamp roller  13  for pressing the web of insulation downwardly against the metal sheet to form a laminate section  14 , guide rails  15  for supporting the metal sheet/laminate section, and conveyor belts  16  extending along the guide rails for feeding the metal sheet/laminate section under the clamp roller and then under an array of rivet guns  17 . The array of rivet guns is movable along tracks extending above and substantially parallel to the guide rails and is operable to fire at least one line of rivets  18  through the laminate section for firmly attaching the web of insulation to the metal sheet. Prior to being clamped together by the clamp roller, the metal sheet is severed from its coil by a hydraulic shear (not shown) and the web of insulation is severed from its roll by an insulation cut off assembly  20 . Optionally, a glue gun (not shown) can be included between the clamp roller and the roll of insulation. The glue gun, if included, is operable to deposit adhesive across an upper surface of the metal sheet or a lower surface of the web of insulation, prior to the clamp roller pressing the web of insulation downwardly against the metal sheet. For examples, the glue gun can squirt one or more beads of glue onto the metal sheet, or can spray one or more bands or spots of tack adhesive onto the web of insulation. The entire apparatus can be manually operated, or can be automatically operated by a pre-programmed controller  100 . 
         [0013]    Referring to  FIGS. 2-6 , the insulation cut off assembly  20  includes a frame  22 , a cut off blade  24  movable within the frame along an arcuate path  66 , an air cylinder or other linear actuator  26  connected between the frame and the cut off blade for moving the cut off blade within the frame, and a cutting stick  28  fixedly mounted across a lower side of the frame for supporting the web of insulation within the frame. The cutting stick and the frame together define an opening of the cut off assembly, through which the web of insulation  10  is fed from an upstream side facing the roll  11  to a downstream side facing the clamp roller  13 . 
         [0014]    The frame  22  includes a left support  32  and a right support  34 . Each support has an end bumper  36  fixed to an inner face of the support. The supports are joined at their upper ends by a top crossover bar  38 . The top crossover bar includes left and right pivot spacers  42  and an air cylinder mount  44 . Each pivot spacer has a link pin  46  protruding therefrom to define a pivot mount point. The pivot spacers define a pivot line that extends substantially parallel to the plane of the frame. However, the pivot line can be somewhat skewed from the plane of the frame if for any reason it becomes desirable to cut the web of insulation at an angle other than perpendicular to its motion through the frame. Optionally, an insulation edge sensor (not shown) can be mounted on the crossover bar between the pivot spacers, and can (for example) be any of a photoswitch, a deflectable finger switch, or a rotary encoder positioned to be rotated by contact with the web of insulation. 
         [0015]    The cut off blade  24  includes a knife body  48 , a blade holder  52 , and a clamp bar  54  securing the knife to the blade holder. Preferably, the knife has a hardened wavey cutting edge  56  for slicing the insulation. The knife also can have a straight edge or a scalloped edge. The blade holder includes two pivot pins  58  and a trunnion mount  62  with the trunnion extending substantially perpendicularly to the body of the knife. 
         [0016]    The cut off blade  24  is supported within the frame  22  by pivot links  64  connected between the blade holder pivot pins and the pivot spacer link pins. One (fixed) end of the air cylinder  26  is pivotally connected to the air cylinder mount on the frame, and the other (working) end of the air cylinder is pivotally connected to the trunnion of the blade holder, so that the cut off blade is swingably movable along the curvilinear or arcuate path  66  by extension and retraction of the air cylinder. 
         [0017]    The cutting stick  28  extends between bases of the left and right supports. The cutting stick can be any shape, but preferably has a substantially flat upper surface  68  for supporting the moving web of insulation. The upper surface of the cutting stick includes a slot  72  extending the full length of the cutting stick. The slot is disposed in registration with the knife  48 . Optionally, the edge sensor previously discussed can be mounted on the cutting stick proximate or within the slot of the cutting stick. Positioning the edge sensor within the slot could be particularly effective for a photosensor, which could then detect the insulation edge based on a change in the light within the slot. 
         [0018]    In operation, the air cylinder  26  can be either fully extended or fully retracted to hold the knife  48  away from the cutting stick  28 . The sheet or web of insulation  10  is fed through the cut off assembly  20  to a desired length. The air cylinder then is extended or retracted to pivot the cut off blade downward and upward within the frame. As the cut off blade swings downward and upward, the knife moves horizontally across and vertically through the insulation to sever the insulation. At a leftward end of the cut off blade&#39;s curvilinear or arcuate path  66 , the knife edge  56  is disposed a set distance above the cutting stick  68  and the left end of the blade holder  52  contacts the end bumper  36  of the left support; at a rightward end of the path, the knife edge again is disposed the same distance above the cutting stick and the right end of the blade holder contacts the end bumper of the right support. At the lowest point reached by the cut off blade, approximately midway along the curvilinear path, the knife passes below the upper surface of the cutting stick and into the slot  72  to make a clean cut of the insulation without contacting the cutting stick. Thus, the slot permits the insulation to be cut cleanly to a desired length without binding, partial cuts, or ragged edges and without wearing the knife through contact with the cutting stick. 
         [0019]    Additionally, the slot prolongs the useful life of the knife with fiberglass insulation. Fiberglass is very abrasive and will quickly dull the cutting edge  56 ; however, the dull knife  48  will continue to cut and fracture the fiberglass because of the narrow slot formed in the cutting stick. When switching from fiberglass insulation to conformable foam insulation, a new knife blade is preferred for optimal cutting. 
         [0020]    Referring back to  FIG. 1 , the electronic controller  100  houses a processor  102  pre-programmed to operate the cut off assembly  20 , the clamp roller  13 , the glue gun, and the rivet guns  17  according to production line speed and desired part length and also houses a keypad, touch screen, USB or other communications port, wireless antenna and signal decoder, or similar means  104  for re-programming the processor. Once programmed, the controller will detect the leading edge of an incoming insulation piece  10  based on an edge-detect signal received from the edge sensor. Alternatively, an operator can pre-feed the web of insulation through the frame and initiate motion of the insulation; at startup of the apparatus, the controller then can direct extension or retraction of the pneumatic actuator to make a first cut. Based on process variables such as (but not limited to) programmed line speed and elapsed time from a previous cut, or elapsed time from detection of the insulation leading edge, the controller can estimate a length of insulation passed through the frame, and can accordingly actuate the glue gun to apply adhesive to the metal sheet, lower and raise the clamp roller to engage and release the web of insulation and the metal sheet, operate the cut off apparatus to cut off the insulation at a desired length, and trigger the rivet guns to pin the insulation to the metal sheet at pre-determined locations. For example, line speeds of twenty-five (25) and fifty (50) feet per minute are typical. 
         [0021]    Typically, the apparatus is controlled so that the cut-off blade  24  does not sever the web of insulation  10  until the downstream end of the insulation has been clamped against the metal sheet by the clamp roller  13 . This mode of operation ensures positive alignment of the insulation to the sheet metal to form a laminate section, in preparation for perforation and fastening of the laminate structure by the array of rivet guns  17 . 
         [0022]    Although the invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and the scope of the invention. For example, a skilled human operator using mechanical switches and buttons, and responding in real-time to process conditions, can control the apparatus  12 . Equally, the apparatus can be controlled by an enhanced electronic controller programmed to respond in real-time to process conditions including (for example) line speed, engagement of the insulation with the clamp roller  13 , operation of the glue gun, and stock levels of the glue gun and of each of the array of rivet guns  17 .