Abstract:
A method of making evaporative cooler pads having a mat of absorbent material substantially uniformly distributed throughout the mat to provide the desired thickness and density to efficiently cool by evaporation warm air that is passed through the mat attached to an evaporative cooler system. The absorbent material can comprise excelsior in the form of aspen wood fibers. This material is cut into mats of the desired size and separated from other mats to create gaps between the mats. A mesh netting encloses the mat and the gap between mats. A stitching machine adds stitching to the mat and to the netting in the gaps between mats to bind the netting to the mat and to interconnect the netting layers in the gap. Adhesive material is applied to the netting and stitching in the gaps to retain the mat inside the netting. A cutting assembly cuts in the gap between the mats to form individual cooler pads. The sealed ends of the netting beyond the mats prevents loss of absorbent material and assists in maintaining the mat in a sufficiently stable mass to be utilized as a cooler pad.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The field of the present invention relates generally to the assembly of evaporative cooler pads that are used in evaporative coolers for absorbing water to cool warm air that flows through the cooler pad and into a cooling system. In particular, the present invention relates to the manufacturing of evaporative cooler pads that utilize absorbent media contained in a mesh material. 
     2. Background 
     Evaporative cooler systems are commonly used in warm areas having relatively low humidity to produce cool air for use to cool the interior of houses, businesses and other structures at a relatively low cost. Such systems employ an evaporative cooler having a cabinet-like housing with one or more cooler pads located on the outer edge(s) of the housing. The evaporative cooler housing is typically located on or near the structure to pull warm air into the cooler, cool the air and deliver it through one or more vents located in the structure to distribute cool air in the structure&#39;s interior. Cooling of the warm air is achieved by pulling warm air across the wetted cooler pad or pads with the use of a fan or blower mounted inside the housing. A water circulation system including a pump, source of water and a water distribution mechanism located inside the housing supplies water to the cooler pad to keep it in a wetted condition so that it can effectively cool the warm incoming air by evaporation. 
     The typical evaporative cooler housing is made into a square or rectangular shaped open frame, although other shapes are also suitable, that is configured to demountably hold a cooler pad containment structure at the open faces of the housing frame. Typically, the cooler pad containment structure contains the cooler pad in an upright position so that water from the water circulation system flows down across and through the cooler pad to wet substantially the entire absorbent media in the cooler pad. In general, the cooler pad is sized and configured to fit inside the containment structure so as to completely fill the open faces of the housing frame. 
     The wettable cooler pad medium may be formed of any suitable material that is capable of absorbing water and allowing air to pass through the cooler pad. Although recent cooler pads have utilized a number of synthetic materials as the wettable medium, the most commonly used material is wood excelsior. Excelsior cooler pads are generally made from fine aspen wood fibers which are interwoven in a randomly orientated pattern to form a highly porous, absorbent material that has been found to be very effective for evaporative cooler systems. The typical excelsior cooler pad has a plastic or cloth netting that contains the excelsior media in a square or rectangular pad shape. Spikes or wires used in the typical containment structure penetrate the cooler pad to hold the cooler pad in place against the open face of the housing and maintain it as a non-sagging mass. 
     The manufacturing of the excelsior cooler pad typically involves forming a continuous mat of excelsior fibers of the desired width and thickness on an automated conveyor belt assembly either directly from the excelsior manufacturing process or from bales of excelsior material. The netting, typically made of polypropylene material, is applied to the upper and lower surfaces of the cut mat to form a continuous flow between the upper and lower netting. A stitching machine sews stitching material into the pad to hold the excelsior pad between and to the upper and lower netting. The continuous sheet of pad and netting is cut to the desired length. To avoid loss of material from the cut ends of the pad, the ends are stitched or glued together or, alternatively, a narrow strip or piece of netting is applied to each end and then sewn or glued on. The end stitching or gluing requires a separate step in the manufacture of cooler pads presently available. 
     To avoid the extra step of sealing the ends, some cooler pad manufactures cut the excelsior pad prior to placing the netting on the pad so as to obtain a gap between pad sections that will only have netting. Glue is applied to the surface of the pad, including the netting gap, and then the netting between the pad sections is cut, leaving the ends sealed by the glued netting. Although this method of manufacturing avoids the necessity for an extra sealing step, it does not provide an end seal that is as strong and durable as desired or adequately secure the netting to the pad. What is needed is a process of manufacturing a cooler pad that provides a stitched cooler pad with ends that are sewn, without the need for the extra step of sewing the ends after manufacture of the cooler pad, and that has the netting securely combined with the excelsior fibers. 
     SUMMARY OF THE INVENTION 
     The method of manufacturing cooler pads of the present invention solves the problems identified above. That is to say, the present invention provides a process of manufacturing cooler pads that fixedly seals the ends of the cooler pads with sewing material without the need for a separate end sewing step and that securely connects the netting to the fibers. As such, the method of the present invention is particularly suitable for automated processes that provide continuous flow manufacturing of evaporative cooler pads. 
     In the primary embodiment of the present invention, the method of manufacturing evaporative cooler pads starts with a source of absorbable, porous media that is placed on a first conveyor belt assembly. The media is shaped into a continuous mat of such material and compressed into the desired width, thickness and density. A first cutting assembly cuts the continuous mat into individual mats having the desired length. The pulling action of a second conveyor belt assembly creates a gap between cut mats. After the second conveyor belt assembly pulls the cut mat away from the continuous mat, mesh netting is placed on the opposing upper and lower surfaces of the individual mats. 
     After covering the upper and lower surfaces of the mat and the gap between mats with netting, the method of the present invention folds the lower netting around the sides of the mat and over on top of the mat and applies rows of stitching to the netting and mat. The stitching fixedly attaches the netting to the upper and lower surfaces of the mat to contain the mat inside the netting material. The netting in the gap between mats is also stitched to seal the ends of the netting and avoid loss of mat material and sagging of the mat. After stitching, adhesive material is applied to the netting and stitching in the gap between mats by spraying or other mechanism to further seal the ends of the netting and keep the stitching from unraveling after it is cut. Compression rollers further compress the mat and a second cutting assembly cuts the netting between the mats to form a cooler pad of the desired length. A take-off conveyor belt assembly takes the completed cooler pad off the belt conveyor system. 
     Accordingly, the primary objective of the present invention is to provide a method of manufacturing evaporative cooler pads that provides a cooler pad that effectively contains the absorbent material in the cooler pad that does not require an extra finishing step to seal the ends of the pad. 
     It is also an important objective of the present invention to provide a method of manufacturing cooler pads that utilizes a system of continuous stitching to seal the ends of the cooler pad that is suitable for use with automated cooler pad manufacturing systems. 
     It is also an important objective of the present invention to provide a method of manufacturing cooler pads that seals the stitched ends of the cooler pad with an adhesive to further strengthen the ends thereof and keep the stitches from becoming unraveled or undone. 
     It is also an objective of the present invention to provide a method of manufacturing cooler pads with stitched and sealed ends that is suitable for use with different types of absorbent media to produce a variety of different size cooler pads. 
     The above and other objectives of the present invention will be explained in greater detail by reference to the attached figures and the description of the preferred embodiment which follows. As set forth herein, the present invention resides in the novel features of form, construction, mode of operation and combination of processes presently described and understood by the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate the best modes presently contemplated for carrying out the present invention: 
     FIG. 1 is a perspective view of an evaporative cooler pad made by the preferred embodiment of the present invention; 
     FIG. 2 is a perspective view of the mat utilized in the method of the present invention; 
     FIG. 3 is a block diagram of the basic steps of manufacturing evaporative cooler pads according to the present invention; 
     FIG. 4 is a side view of an automated process utilizing the method of manufacturing evaporative cooler pads of the present invention; 
     FIG. 5 is a schematic showing various steps in the method of the present invention; and 
     FIG. 6 is a close-up view of the gap between mats that is utilized in the method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to the figures where like elements have been given like numerical designations to facilitate the reader&#39;s understanding of the present invention, and particularly with reference to the embodiment of the present invention illustrated in FIGS. 1 through 6, the preferred embodiment of the present invention is set forth below. FIG. 1 illustrates the evaporative cooler pad  10  made from the method of manufacturing evaporative cooler pads of the present invention, designated generally as  12 , and shown in FIGS. 3 through 5. Cooler pad  10  is formed from a mat  14 , shown in detail in FIG. 2, of substantially uniformly distributed absorbent media, such as aspen wood fibers (excelsior)  16  or other varieties of natural cellulosic materials, such as paper or other wood products. Aspen wood fibers  16  are commonly used due to the superior qualities, including its availability, cost and ease of forming into wood fibers to create a mat  14  having an open cellular structure providing a highly absorbent mat  14  that holds more water and creates more evaporative wicking area per square inch than many other materials. The natural wood of the excelsior material  16  also reduces the likelihood of objectionable odors from the cooling system. 
     In the preferred embodiment, wood fibers  16  are thinly cut into individual segments that enable them to be mechanically layered and oriented in a generally horizontal plane in a mat  14  of uniform thickness and density having opposing upper surface  18  and lower surface  20  and opposing first edge  22  and second edge  24 . Typical dimensions of such individual segments used by those in the industry are 0.042 inch width, 0.021 inch thickness and 18 inch length. As is known by those skilled in the art, a variety of sizes of the individual segments are available for the absorbent material. If the segments are too small, they will break easily and not stay together as a mat. If the segments are too large, the amount of surface area available for contact with the warm air will be substantially diminished, thereby reducing the cooling efficiency of the pad. Also in the preferred embodiment, the wood fiber segments are curled and barbed during the cutting process for added water holding capability. The wood fibers  16  are layered in a direction generally parallel with opposing upper  18  and lower  20  surfaces. The wood fibers  16  become intertwined and interwoven to form a plurality of interstices and passageways throughout mat  14  so that water may be absorbed by wood fibers  16  and warm air directed at cooler pad  10  may flow generally freely and uniformly through the pad  10  and into the cooling system after being cooled by heat transfer between the wetted mat  14  and the air. 
     To facilitate handling of pad  10  and to ensure the wood fibers  16  remain in the pad  10 , a mesh netting  26  abuts against the surfaces of mat  14 . Typically, netting  26  is made of a polypropylene plastic material having mesh openings  28  that are formed from approximately six strands per inch in each direction. Mesh openings  28  must be sized to contain wood fibers  16  in mat  14  without inhibiting the flow of air through pad  10  when in use. If mesh openings  28  are too large, pieces of wood fibers  16  from mat  14  would pass through pad  10  and into the cooler&#39;s water circulation system where it could clog pumps, water distribution systems and filters. Upper netting layer  30  abuts against the upper surface  18  of mat  14  and the lower netting layer  32  abuts against the lower surface  20  of mat  14 . In the method of manufacturing set forth below, the netting  26  on an individual cooler pad  10  extends beyond the first  22  and second  24  edges of mat  14 . To facilitate the reader&#39;s understanding of the method set forth herein, the netting extending beyond the first edge  22  of mat  14  is referred to as the first net end  34  and the netting extending past the second end  24  of mat  14  is referred to as the second net end  36 . First  34  and second  36  net ends should provide sufficient space between the end of the netting  26  and the first  22  and second  24  edges to provide room to contain loose fibers. 
     Netting  26  is secured to mat  14  with rows of stitching  38  spaced across the mat as preferred by the manufacturer. In the preferred embodiment of the cooler pad  10  of the present invention, the stitching rows are spaced apart approximately every two inches. The stitching  38  runs the entire length of the cooler pad  10  from first net end  34  to second net end  36 . Those prior art cooler pads that utilized stitching  38  similar to that set forth herein, but which required the edges of the mat  14  to be separately stitched, only have stitching  38  running from the first edge  22  to the second edge  24  of mat  14 . Stitching  38  penetrates mat  14  to stabilize and unitize the wood fibers  16  in mat  14  to substantially eliminate sagging of pad  10  when placed in a vertical position, as used in the typical cooling system. The stitching  38  can be made from plastic or a biodegradable material such as jute, cotton or other natural fibers. 
     The evaporative cooler pad  10  described above is manufactured by the process  12  described below and illustrated in FIGS. 3 through 5. The block diagram in FIG. 3 illustrates the basic steps in the process of manufacturing cooler pad  10 . FIG. 4 illustrates the equipment and various steps utilized in manufacturing the cooler pad  10  of the preferred embodiment. The basic steps of manufacturing cooler pad  10 , as shown in FIG. 3, requires a supply of individual mats  14  separated from each other a sufficient distance to create first  34  and second  36  ends of netting beyond the first  22  and second  24  edges of mat  14 . Netting  26  is placed in surrounding relation to mat  14  by placing upper netting layer  30  against upper surface  18  and lower netting layer  32  against lower surface  20 . Rows of stitching  38  are applied to mat  14  to fixedly attach netting  26  to mat  14  and to seal the first  34  and second  36  ends of netting to form the excelsior  16  or other materials into a cooler pad  10  that will withstand sagging and prevent loss of excelsior material from pad  14 . Adhesive material, such as plastic hot melt type  80860  available from SWIFT, is applied to the first  34  and second  36  ends of netting to seal mat  14  inside netting  26 . A cutting device then cuts the netting  26  between a pair of mats  14  to form individual evaporative cooler pads  10 . The cooler pads can then be packaged and stacked for shipping. 
     As shown in the detailed illustration in FIG. 4, the method  12  of the preferred embodiment of the present invention starts with a supply of pad  14  material, preferably a supply of fibrous material such as excelsior  16 . Typically, the supply of excelsior  16  is provided in bales  40  that are placed on bale conveyor  42  to feed the bales  40  into a bale breaker  44 . Bale breaker  44  breaks the bales  40  into a loose mix of excelsior  16  that is then fed into blower  46  that blows the excelsior  16  through blower line  47  into box feeder  48  and picker  49 , which places a continuous stream of excelsior  16  in an elongated mat  50  on a first conveyor belt assembly  52 . 
     The mat  50  deposited on first conveyor belt assembly  52  is compressed by one or more compression rollers  54  to form the uniformly thick and dense material needed for mat  14 . After the elongated mat  50  passes under the first cutting assembly  56  and is cut into the desired length for mat  14 , the mat  14  is pulled across shelf  57  by a second conveyor belt assembly  58  that moves at a higher speed than the first conveyor belt assembly  52 . The increased speed from the pulling action of the second conveyor belt assembly  58  separates the cut mat  14  from the elongated mat  50 , creating gap  60  between the cut mats  14 , as shown in FIGS. 5 and 6. As the second conveyor belt assembly  58  pulls mat  14  from elongated mat  50 , netting  26  is placed on mat  14  from a pair of netting rolls  62  and  64 . Netting roll  62  supplies upper netting layer  30  against upper surface  18  and netting roll  64  supplies lower netting layer  32  against lower surface  20 . After netting  26  is placed on mat  14 , drum roller  65  presses down on mat  14  while lower netting  32 , which is wider than mat  14 , is folded over opposing sides  68  and  70  of mat  14  onto mat  14  by folding device  66 . Roller  72  compresses mat  14  and netting  26  to form mat  14  with netting  26  into the desired thickness and density. Second conveyor belt assembly  58  then feeds mat  14  into stitching machine  74 . Alternately, a separate conveyor belt assembly (not shown) can be utilized to feed mat  14  into stitching machine  74 . 
     Stitching machine  74  applies rows of stitching  38  to the mat  14  to bind the netting  26  to mat  14 , including that portion of the netting folded over from sides  68  and  70 . As is known in the art, each row of stitching  38  can be a single thread having a double loop at the bottom. The stitching  38  is continuously applied by stitching machine  74  to the mat  14  and netting  26 , such that the netting  26  in gap  60  also contains stitching  38 . Unlike prior art methods of making evaporative cooler pads, which did not stitch the netting  26  in gap  60 , the method of the present invention stitches the netting  26  in the gap  60  to more securely seal the first  34  and second  36  ends of netting  26  to prevent loss of excelsior  16  and collapse or breakdown of mat  14 . Loss of excelsior  16  or breakdown of mat  14  is likely to result in damage to or clogging of the water circulation system in the evaporative cooler, requiring increased repair and maintenance, and loss of efficiency for the entire cooling system. The cooler pad  10  made by the method of the present invention reduces the likelihood of such problems, resulting in a more efficient cooling system that requires less repair and maintenance. 
     After stitching  38  is applied to the flow of mats  14 , As stitching is applied to the flow of mats  14 , double draw rollers  76  pull the flow of mats  14  through the stitching machine  74 . Double draw rollers  76  are used so that at least one set of rollers are on mats  14  at all times to hold the netting  26  taut and to pull mat  14  through stitching machine  74  at a constant speed. After stitching is applied, draw roller  82  pulls the flow of mats  14  under adhesive applicator  78  to apply an adhesive material, such as plastic hot melt, to the netting  26  and stitching  38  in the gap  60 . Adhesive applicator  78  can comprise one or more spray head assemblies (not shown) suitable for spraying hot melt or other adhesives across gap  60  to seal the netting  26  and stitching  38  in the gap  60 . After applying the adhesive, the draw rollers  82  pull the flow of pads  14  under a second cutting assembly  84  to cut the netting  26  and stitching  38  in gap  60  to form cooler pad  10  having sealed ends  34  and  36 . A take-off conveyor belt system  86  removes the cut pads  10  from the conveyor system  52 . Prior to removing the pads  10  from the conveyor system  52 , the pads can be covered by plastic or paper material, or other materials as desired, to protect the cooler pads  10  during shipment and make them more presentable for retail sales. 
     While there is shown and described herein certain specific alternative forms of the invention, it will be readily apparent to those skilled in the art that the invention is not so limited, but is susceptible to various modifications and rearrangements in design and materials without departing from the spirit and scope of the invention. In particular, it should be noted that the present invention is subject to modification with regard to the dimensional relationships set forth herein and modifications in assembly, materials, size, shape, and use.