Abstract:
A heat shrink tunnel with width adjustment includes a pair of opposing side wall assemblies, each assembly including an outer wall and an inner perforated wall defining a plenum therebetween. The opposing side walls define a product path therebetween having a longitudinal axis. The side wall assemblies are movable toward and away from the axis. A heater/blower assembly is disposed in each of the opposing side walls, each having an outlet directed into the product path and drawing air from the product path, through its respective plenum. A top wall extends between the pair of opposing side wall assemblies and has an adjustable width to accommodate movement of the side wall assemblies.

Description:
BACKGROUND 
       [0001]    Devices are known for wrapping or securing items for handling, transport and the like. Often, multiple items are placed together, bundled and a shrink wrap material is positioned around the items. The shrink wrap material is then heated to shrink around the bundled load. Such shrink wrap maintains the stability of the load and can provide protection against environmental conditions, such as water, dirt and the like. 
         [0002]    Heating the shrink wrapped load is often carried out in a shrink wrap tunnel. Typically, a load to be shrink wrapped is presented to the tunnel on a conveyor. The load is wrapped with the material, which shrinks when subjected to heat. The load is conveyed through the tunnel and as it moves through the tunnel, heat, typically applied by forced air heaters, is blown over the wrapped load. The heat is sufficient to shrink the wrap onto the load to create a tightly wrapped package. 
         [0003]    Known shrink wrap tunnels, include stationary walls. Because the heating elements are mounted to the walls, they too are stationary relative to the load moving through the tunnel, regardless of the size, or width of the load. 
         [0004]    Loads, however, can consist of a wide variety of items, materials and the like, of a likewise wide variety of sizes. As such, there can be significant inefficiencies in heat shrink tunnels, especially when, for example, a narrow load is conveyed through a relatively wide tunnel. That is, the tunnel may be quite large, and the load much smaller. Thus, there are thermal losses and inefficiencies due to convective losses. 
         [0005]    Accordingly, there is a need for a shrink wrap tunnel the reduces the inefficiencies inherent in the shrink wrapping process. Desirably, such a shrink wrap tunnel has a width that can be varied to accommodate loads having a variety of widths. More desirably, in such a shrink wrap tunnel, hot air can be directed or forced into open spaces around a wrapped load and drawn from the wrapped load, to minimize heat losses. 
       SUMMARY 
       [0006]    A heat shrink tunnel has dynamic width adjustment. The tunnel includes a pair of opposing side wall assemblies. Each assembly includes an outer wall and an inner perforated wall that define a plenum therebetween. The opposing side walls define a product path therebetween, that defines a longitudinal axis through the tunnel. The side wall assemblies being movable toward and away from the longitudinal axis to vary the width of the product path. 
         [0007]    A heater/blower assembly is disposed in each of the opposing side walls. Each heater blower assembly has an outlet directed into the product path and draws air from the product path, through its respective plenum. 
         [0008]    A top wall extends between the pair of opposing side wall assemblies and has an adjustable width to accommodate movement of the side wall assemblies. 
         [0009]    In a present embodiment, the heat shrink tunnel has a conveyor for moving product through the tunnel. The conveyor can define a floor for the heat shrink tunnel. The conveyor can include a conveying element, such as a belt, that is narrower than the distance between the tunnel walls and the conveyor width can be adjustable to, for example, accommodate the product width. 
         [0010]    The top wall can be formed having an accordion-fold configuration to permit adjustment of the width thereof. 
         [0011]    The tunnel can include front and rear walls at the entrance to and exit from the tunnel. The front and rear walls can be operably connected to one or both of the side wall assemblies and can likewise have an adjustable width to accommodate movement of the side wall assemblies. 
         [0012]    The height of the front and rear walls can be adjustable to vary the height of the entrance to and exit from the tunnel. In such an embodiment, the front and rear walls can be formed having an accordion-fold configuration to permit adjustment of the width of the front and rear walls, respectively. 
         [0013]    The inner perforated walls are preferably formed from or coated with a low-stick or non-stick material to reduce the opportunity for shrink wrap material to stick to the walls. Insulation can be disposed at about the outer walls to reduce heat losses. 
         [0014]    In one contemplated embodiment, heat shrink tunnel includes a controller. In such an embodiment, one or more drives can be configured for moving the side wall assemblies toward and away from the longitudinal axis. Such an embodiment can include sensors for sensing the width of the load, and the side wall assemblies can be moved, such as by the drives, in response to the sensed width of the load. 
         [0015]    These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of a shrink wrap tunnel with dynamic width adjustment; 
           [0017]      FIG. 2  is a view similar to  FIG. 1 , and showing a portion of the side wall out wall broken away; 
           [0018]      FIG. 3  is a perspective view of a portion of the shrink wrap tunnel shown broken away and showing a load positioned on the conveyor; 
           [0019]      FIGS. 4 and 5  are front side illustrations of the tunnel showing the tunnel width being increased and decreased; and 
           [0020]      FIG. 6  is another perspective view of the shrink wrap tunnel. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    While the present device is susceptible of embodiment in various forms, there is shown in the figures and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification of the device and is not intended to be limited to the specific embodiment illustrated. 
         [0022]    Referring to the figures and in particular to  FIG. 1  there is shown an exemplary shrink wrap tunnel  10  with dynamic width adjustment. The tunnel  10  is typically associated with a conveyor  12  to convey a load L through the tunnel  10 . The conveyor  12  can define a bottom wall or floor for the tunnel  10 . The conveyor can include a conveying element  13 , such as a belt, chain, or other conveying medium for moving the load L or product through the tunnel  10 . The conveyor  12  width can be adjustable to, for example, accommodate the product L width. 
         [0023]    The tunnel  10  includes a pair of side wall assemblies  14  and a top or ceiling  16 . The side wall assemblies  14  are moveable toward and away from each other (or a centerline A 12  of the conveyor  12 ) so as decrease or increase the distance d 14  between the walls  14 . In a present embodiment, the side wall assemblies  14  include outer walls  18  that are curved, bowing outward at about the middle of the walls (as indicated at  20 ) and inward at the lower and upper junctions with the floor (or conveyor  12 ) and top  16 , respectively. 
         [0024]    The top  16  is configured so that it expands and collapses to maintain a closed ceiling as the side wall assemblies  14  are moved outwardly and inwardly. In a present embodiment, the top  16  is configured with an accordion panel  21  that expands and contracts to accommodate the movement of the side wall assemblies  14 . Other wall expansion and contraction configurations can be provided to accommodate side wall assembly movement. For example, sliding panels can also be used. 
         [0025]    In a present embodiment front and rear walls  22 ,  24  can be provided for the tunnel  10 . The front and rear walls  22 ,  24  can also be configured to accommodate side wall assembly  14  movement by use of accordion walls/panels  26 ,  28  as shown, sliding panels and the like. In addition the front and rear walls  22 ,  24  can also include panels (front  30  shown, rear not shown) that allow for adjusting the height h of the tunnel opening O. As illustrated in  FIG. 1 , the panels (front  30  shown, rear not shown) can slide upward and downward to increase and decrease the height h of the tunnel opening O. It will be appreciated that the adjustment of the tunnel opening O height h will allow for minimizing heat losses from the tunnel  10 . 
         [0026]    The side wall assemblies  14  each include an inner wall  34  that, with their respective outer walls  18  each define an air plenum  36 . The inner walls  34  are perforated or foraminous, as indicated at  38 , to permit air flow between the tunnel  10  and the plena  36 . In a present configuration, the inner, perforated walls  34  are formed from or coated with a low-stick or non-stick material, such as a metal coated with, for example, a Teflon® material coating to prevent shrink wrap material or debris from sticking to the walls  35 , which could otherwise reduce airflow through the walls  34 . 
         [0027]    A heater/blower assembly  40  is positioned in each of the side wall assemblies  34 , in each plenum  36 . As seen in  FIG. 3 , the heater/blower assembly  40  is located between the inner  34  and outer  18  walls near the bottom of the plenum  36 . The heater/blower assembly  40  includes a centrifugal blower or fan  42  and a heat source  44 . Outlet vents  46  are positioned at the outlet of each of the assemblies  40 . In a present embodiment the heat source  44  is an electric heater, such as a resistance wire heater. Other suitable heat sources will be recognized by those skilled in the art. 
         [0028]    As seen in  FIG. 2 , the tunnel  10  can include a layer of insulation  47  within the side wall assemblies  14 . In a present embodiment the insulation  47  is present in the inside of the outer side wall  18  (on the plenum  36  side of the outer side wall  18 ) to further reduce heat losses from the tunnel  10  through the side wall assemblies  14 . 
         [0029]    The shrink tunnel  10  and conveyor  12  system can be mounted to a frame  48 , such as that shown in  FIG. 1 . Support rails  52 , mounted to the frame  48 , can be configured to support the tunnel side wall assemblies  14  and or the top wall  16 , to facilitate movement of the side wall assemblies toward and away from one another (decreasing and increasing the tunnel  10  width or distance d 14  between the side wall assemblies  14 ). The rails  52  can include locks  54  to lock the tunnel side wall assemblies  14  at a desired width d 14 . 
         [0030]    A controller  56  controls the overall operation of the tunnel  10 . Operation can be manual or, optionally, various aspects of the tunnel  10  operation can be automatically controlled. For example, the internal temperature of the tunnel  10  can be monitored and controlled automatically, as can the speed at which the load L moves through the tunnel  10  (e.g., the conveyor  12  speed). It is also contemplated that further automatic operations can be incorporated into the present tunnel  10 . For example, the width d 14  adjustment of the tunnel  10  as well as the height h adjustment of the front and rear walls  22 ,  24  may be carried out automatically. In such an arrangement, drives, such as servomotors or the like, such as indicated at  58  and  60 , can drive the width d 14  adjustment and height h adjustment based upon the width and height of the load L as determined by sensors placed within the system  10 . 
         [0031]    In use, the width (i.e., distance d 14  between the side wall assemblies  14 ) and height h (e.g., front and rear wall openings O) of the tunnel  10  are first set. It is anticipated that a load L will be positioned on the conveyor  12  for presentation to the tunnel  10 . As seen in  FIG. 3 , the load L will have a sleeve S of shrink wrap material positioned around the load L with the open sides D of the sleeve S directed toward the side wall assemblies  14 . As the load L moves along the conveyor  12 , hot air is forced from the heater/blower assembly  40  through the outlet vents and is directed into the wrapped load L. Because the tunnel side wall assemblies  14  are adjusted to contact or nearly contact the inner perforated wall  34  and the edges of the sleeve S, the hot air is essentially all directed into the sleeve S, rather than into the space around or outside of the load L within the tunnel  10 . 
         [0032]    Moreover, because air is drawn into the plenum  36  through the perforated plates  34 , there is a higher pressure region created within the sleeve S, which further facilitates drawing the air from sleeve S around the load L. Essentially, a high pressure region is created at the blower  40  discharge with a low pressure region created within the plenum  36 . In addition, because the sleeve S edge is positioned to contact or nearly contact the perforated wall  34 , the hot air blown into the sleeved load L (see, e.g.,  FIG. 3 ), is drawn out at the top and bottom of the sleeve, thus facilitating the flow of heated air and rapid heat exchange to the shrink wrap material. 
         [0033]    It will be appreciated by those skilled in the art that the relative directional terms such as upper, lower, rearward, forward and the like are for explanatory purposes only and are not intended to limit the scope of the disclosure. 
         [0034]    All patents referred to herein, are hereby incorporated herein by reference, whether or not specifically done so within the text of this disclosure. 
         [0035]    In the present disclosure, the words “a” or “an” are to be taken to include both the singular and the plural. Conversely, any reference to plural items shall, where appropriate, include the singular. 
         [0036]    From the foregoing it will be observed that numerous modifications and variations can be effectuated without departing from the true spirit and scope of the novel concepts of the present disclosure. It is to be understood that no limitation with respect to the specific embodiments illustrated is intended or should be inferred. The disclosure is intended to cover all such modifications as fall within the scope of the claims.