Abstract:
A method of roll packing a variety of compressible materials is provided which prevents the rotatable mandrel about which the materials are rolled from radially collapsing. The method further provides for easy removal of the roll packed material without tearing or-telescoping of the material. One embodiment of the present invention provides for wrapping a corrugated material around the rotatable mandrel prior to the compressible material being wrapped around the mandrel. In another embodiment, roll-packing material is laminated prior to being wound upon,the mandrel before the compressible material is wrapped around the mandrel.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to the packaging of compressible materials such as foam, spring assemblies, mattresses and the like, and is more particularly directed to method of roll packing such compressible materials.  
         BACKGROUND OF THE INVENTION  
         [0002]    Conventional packaging and transportation of compressible materials such as finished mattresses, as well as foam or spring assemblies used in the manufacture of mattress products, generally involves handling of the materials in an uncompressed state. As such, the shipping and storage of the materials requires much more space than would be required if the materials were provided in a compressed state. To improve the efficiency of shipping and storage, foam mattress cores have been packaged in a compressed state by flattening the foam and sealing it in an evacuated bag. See, for example, U.S. Pat. No. 4,711,067 to Magni. This method of packaging foam cores, however, is not useful in packaging spring assemblies. In addition, storage and transportation efficiencies of the foam could be further improved by packaging the flattened cores into a tight roll.  
           [0003]    Roll packing generally involves winding-up a desired material to form a roll and then securing the roll to prevent uncoiling of the roll during handling. In the case of compressible materials such as mattresses and foam or spring cores, it is often desired to compress the materials during the roll packing process to obtain a more dense and compact roll. Various devices have been used to achieve compression of roll packed materials. U.S. Pat. No. 3,927,504 to Forrister discloses an apparatus for rolling, resilient foamed sheet material without the use of a mandrel. This machine is not useful for packaging spring assemblies and does not have the capability to package multiple units of a compressible material into a large roll. The device further does not provide for packaging a compressible material with a barrier layer between successive turns of the roll, which barrier layer is desirable to prevent adhesion between successive layers of foam.  
           [0004]    Some roll packing systems include a mandrel for facilitating the winding of the material. For example, U.S. Pat. No. 2,114,008 to Wunderlich discloses a spring packing machine having a radially collapsible arbor for use in roll packing spring assemblies. A barrier layer between successive turns of the roll keeps the spring assemblies separate and permits easy removal of a single assembly from the roll. However, this machine is not useful for roll packing foam material due to the presence of a pressure bar which would tend to snag a compressed foam as it passed beneath. The disclosed machine also has other drawbacks. For example, to remove a finished roll, the arbor must be removed from the machine and collars must be adjusted to collapse the arbor so that the roll can be taken off the arbor. The arbor must then be replaced in the machine before another roll can be formed. Operation of the machine is thus very labor intensive and ergonomically inefficient.  
           [0005]    The roll packing of spring assemblies, foam cores or other compressible materials onto mandrels has heretofore been a problem because the compressible material does not slide easily off of the mandrel after being rolled up. Difficulties in removing the compressible material from the mandrel are due to the material&#39;s high friction coefficient in combination with the high compression force against the mandrel that is created when the compressed material is wound around the mandrel. When a spring or foam core is compressed onto a mandrel, the material has a natural tendency to want to expand in both radial directions, i.e., to expand radially outward from the mandrel and radially inward to the mandrel. As a result of the inward compressive force, the compressible material essentially sticks to the mandrel.  
           [0006]    Consequently, attempting to withdraw the roll from the mandrel may damage the first few layers of the roll or cause undesirable telescoping or tearing of the rolled material as it is removed from the mandrel. Additionally, the center of the roll may implode once the roll is removed from the mandrel, causing the layers proximate the center of the roll to deform or tear.  
           [0007]    There is thus a need for a method of efficiently roll packing compressible material such as foam or spring cores so that the roll may removed from the mandrel without damaging the rolled material or causing undesirable telescoping or tearing of the rolled material.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention provides a method of roll packing a variety of compressible materials such as foam cores, spring assemblies, and fiber materials used in the manufacture of bedding or seating products, as well as finished mattresses. The machine preferably has a rotatable mandrel with collapsible cleats which permits finished roll packed materials to be easily removed from the machine by sliding the roll off of the mandrel. This type of mandrel, when used in conjunction with the present invention, permits rolled materials to be removed without any telescoping or tearing of the materials which is usually caused by binding of the roll packed material on the mandrel. However, the methods of the present invention may be used with other types of mandrel including those without retractable cleats. The present invention is especially useful in roll packing foam materials which are highly susceptible to binding against a mandrel. The methods of the present invention further permit roll packing practically any compressible material, even materials as diverse as coiled spring assemblies for mattresses and foam cores.  
           [0009]    In accordance with the present invention, a method is provided which employs a mandrel having collapsible cleats for winding compressible materials to be roll packed. A feed table may be provided upstream of the mandrel to support and direct the compressible material to the mandrel. At least one compression roller associated with the mandrel is used to compress in-fed compressible materials in a nip between the compression roller and the mandrel as the material is being wound upon the mandrel. At least one compression roller is adjustable to vary the spacing between the mandrel and the compression roller so that the amount of compression for the in-fed materials can be varied accordingly. The apparatus used to practice of the present invention may be identical to or similar to the apparatus disclosed in applicant&#39;s U.S. patent application Ser. No. 10/066,905, filed on Oct. 22, 2001 entitled APPARATUS AND METHOD FOR ROLL PACKING COMPRESSIBLE MATERIALS, which is fully incorporated by reference herein. However, any other apparatus may be used to practice the present invention. The invention of this application is not intended to limit the apparatus used to employ the methods of the present invention.  
           [0010]    In further accordance with the present invention, a method for roll packing various compressible materials includes the steps of providing a mandrel rotatable about an axis and a compression roller, directing in-fed compressible materials between the mandrel and compression roller, adjusting the spacing between the mandrel and compression roller, winding the compressible material around the mandrel, stopping the mandrel when a desired amount of in-fed material has been wound upon the mandrel, and removing the roll packed material from the mandrel.  
           [0011]    According to one aspect of the present invention, roll packing material such as paper is wrapped around the mandrel before a sheet of corrugated material is fed to the mandrel. Rotation of the mandrel winds the corrugated material around the mandrel at least one revolution. The corrugated material is then secured to itself to form a corrugated sleeve or core around the mandrel. Preferably, the corrugations of the corrugated material are oriented generally perpendicular to the rotational axis of the mandrel. A compressible material such as a continuous web of foam or other compressible material or a series of spring assemblies is fed to the mandrel along with the roll packing material. Rotation of the mandrel causes the compressible material to wind around the mandrel along with the roll packing material which forms a barrier between layers of the compressible material. When a roll of the desired size is achieved, rotation of the mandrel is stopped and the webs of roll packing material and/or compressible material cut. The roll packing material is then wrapped at least once more around the roll and secured to prevent the roll from expanding. The roll is then removed from the mandrel without the roll imploding, thereby damaging the inner layers of the roll. The corrugated sleeve or core provides a protective layer which prevents the roll from imploding.  
           [0012]    According to another aspect of the present inventions a sheet of stiffening material, corrugated or not, is wrapped around the mandrel by rotation of the mandrel. The stiffening material may be secured to itself or to the mandrel; either way, it forms a sleeve or core around the mandrel which prevents the roll from imploding when the roll is removed from the mandrel and thereafter. Next, a compressible material such as a continuous web of foam, a series of spring assemblies or mattresses is fed to into the nip along with roll packing material. Rotation of the mandrel causes the compressible material to wind around the mandrel outside the sleeve or core along with the roll packing material which forms a barrier between layers of the compressible material. When a roll of the desired size is achieved, rotation of the mandrel is stopped and the webs of roll packing material and/or compressible material cut. The roll packing material may then be wrapped at least once more around the roll and secured to prevent the roll from expanding. The roll is then removed from the mandrel without the roll imploding, thereby damaging the inner layers of the roll.  
           [0013]    According to another aspect of the present invention, roll packing material is wrapped once around the mandrel to cover the mandrel. Adhesive or other similar materials are then applied to the roll packing material as the roll packing material is wrapped around the mandrel. As the roll packing material is applied over the existing layers of roll packing material by rotation of the mandrel, the adhesive between the layers of roll packing material drys. The result is a laminated sleeve or core immediately adjacent the mandrel. Once a sufficient number of layers of roll packing material have been wrapped around the mandrel, application of the adhesive is stopped. However, the roll packing material continues to be wrapped around the mandrel along with the compressible material. A compressible material such as a continuous web of foam or a series of spring assemblies is fed to the mandrel along with the roll packing material. Rotation of the mandrel causes the compressible material go wind around the mandrel along with the roll packing material which forms a barrier between layers of the compressible material. When a roll of the desired size is achieved, rotation of the mandrel is stopped and the webs of roll packing material and/or compressible material cut. The roll packing material is then wrapped at least once more around the roll and secured to prevent the roll from expanding. The roll including the sleeve or core is then removed from the mandrel without the roll imploding, thereby damaging the inner layers of the roll. The laminated sleeve or core provides a protective layer which prevents the roll from imploding.  
           [0014]    Accordingly, the invention provides a method for roll packing a variety of compressible materials and which is preferably used in conjunction with a mandrel having collapsible cleats that facilitates the easy removal of finished rolls without tearing, telescoping, or otherwise damaging the roll packed material. These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and description. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the invention.  
         [0016]    [0016]FIG. 1 is a schematic side elevational view showing a roll packing apparatus for use in practicing one embodiment of the method of the present invention and illustrates the step of securing roll-packing material to a rotatable mandrel.  
         [0017]    [0017]FIG. 2 is a schematic side elevational view of the roll packing apparatus of FIG. 1 and illustrates the step of wrapping roll-packing material around the rotatable mandrel.  
         [0018]    [0018]FIG. 3 is a schematic side elevational view of the roll packing apparatus of FIG. 1 and illustrates the step of feeding a sheet of corrugated material to the mandrel.  
         [0019]    [0019]FIG. 3A is a schematic top plan view of the roll packing apparatus of FIG. 1 and illustrates the step of feeding a sheet of corrugated material to the mandrel.  
         [0020]    [0020]FIG. 4 is a schematic side elevational view of the roll packing apparatus of FIG. 1 and illustrates the step of wrapping the sheet of corrugated material around the mandrel.  
         [0021]    [0021]FIG. 5 is a schematic side elevational view of the roll packing apparatus of FIG. 1 and illustrates the step of feeding a compressible material to the mandrel.  
         [0022]    [0022]FIG. 6 is a schematic side elevational view of the roll packing apparatus of FIG. 1 and illustrates the step of compressing the compressible material.  
         [0023]    [0023]FIG. 7 is a schematic side elevational view of the roll packing apparatus of FIG. 1 and illustrates the step of wrapping the compressible material around the mandrel.  
         [0024]    [0024]FIG. 8 is a perspective view of the stop of cutting the roll packing material to form a roll of the desired size.  
         [0025]    [0025]FIG. 9 is a perspective view of a mandrel used in accordance with the present invention.  
         [0026]    [0026]FIG. 9A is an end view of the mandrel of FIG. 9 showing the cleats in an expanded position.  
         [0027]    [0027]FIG. 9B is an end view of the mandrel of FIG. 9 showing the cleats in a collapsed position.  
         [0028]    [0028]FIG. 10 is a schematic side elevational view showing a roll packing apparatus for use in practicing an alternative embodiment of the method of the present invention and illustrates the step of securing roll-packing material to a rotatable mandrel.  
         [0029]    [0029]FIG. 11 is a schematic side elevational view of the roll packing apparatus of FIG. 10 and illustrates the step of wrapping roll-packing material around the mandrel.  
         [0030]    [0030]FIG. 12 is a schematic side elevational view of the roll packing apparatus of FIG. 10 and illustrates the step of wrapping roll-packing material with adhesive applied thereto around the mandrel.  
         [0031]    [0031]FIG. 13 is a schematic side elevational view of the roll packing apparatus of FIG. 10 and illustrates the step of stopping the application of adhesive to the roll packing material.  
         [0032]    [0032]FIG. 14 is a schematic side elevational view of the roll packing apparatus of FIG. 10 and illustrates the step of feeding a compressible material to the mandrel.  
         [0033]    [0033]FIG. 15 is a perspective view of the stop of cutting the roll packing material to form a roll of the desired size. 
     
    
     DETAILED DESCRIPTION  
       [0034]    An apparatus and methods are provided for roll packing compressible materials about a rotatable mandrel so that a completed roll may be removed from the mandrel in a simple and efficient manner without damaging the materials, and wherein the materials can be stored and shipped in a compact state. The methods of the present invention will be described and understood by a description of an exemplary apparatus. However, the methods of the present invention may be used on any suitable apparatus.  
         [0035]    With reference to FIG. 1, there is shown an illustration of one embodiment of roll packing apparatus  10  incorporating the principles of the present invention. The apparatus  10  includes a rotatable mandrel  12  for receiving in-fed compressible materials  14  and winding them into a roll. Although the compressible materials  14  are illustrated as being spring units, the compressible material may be foam or any other type of compressible material.  
         [0036]    As best illustrated in FIG. 9, the mandrel  12  rotates about a rotational axis A and is fixed to a shaft  16  that is driven by a driving mechanism (not shown). The mandrel  12  is generally cylindrical in shape and has an outer surface  18  and a pair of end surfaces  20 . The mandrel  12  has a plurality of aligned, spaced cleats  22  which are movable between a first expanded position illustrated in FIG. 9A and a second collapsed position illustrated in FIG. 9B. The cleats  22  may be moved between positions either mechanically, via air pressure, or via any other means. As seen in the drawings of this application, the cleats  22  are extended in their expanded position while the mandrel  12  is being rotated and collapsed radially inwardly into their collapsed position prior to a completed roll being removed. In accordance with the methods of the present invention, when the cleats  22  are in the collapsed position shown in FIG. 9B, a completed roll may be easily removed from the mandrel  12  without tearing, telescoping or otherwise damaging the compressible material which is roll-packed.  
         [0037]    A pair of compression rollers  24  are located proximate the mandrel  12 . Each compression roller has an axis generally parallel the rotational axis A of the mandrel  12 . The relative positions of the compression rollers  24  and mandrel  12  may be adjusted to either increase or decrease the spacing  26  between their respective outer surfaces. The spacing  26  between the mandrel  12  and the compression rollers  24  determines the amount of compression to be applied to the compressible material  14 . A feed table  28  may be located upstream of the mandrel  12  and compression rollers  24 . Although two compression rollers  24  are illustrated and described, any number of compression rollers including only one may be used in accordance with the methods of the present invention. Although a feed table  28  is illustrated and described any other support such as a conveyor may be used to feed compressible materials  14  into the spacing or nip  26  between one of the compression rollers  24  and the mandrel  12 .  
         [0038]    Referring to FIGS. 1-8, one embodiment of the method of the present invention is illustrated. Referring to FIG. 1, a supply roll  30  of roll packing material  32  such as paper is provided. The roll packing material  32  may alternatively be stacked or stored in other manner without departing from the spirit of the present invention. The roll packaging material  32  is wrapped around guide rollers  34  and attached to the outer surface  18  of the mandrel  12 . As seen in FIGS. 1-7, the retractable cleats  22  of the mandrel  12  are extended in the expanded position.  
         [0039]    Referring to FIG. 2, the mandrel  12  is rotated, thereby wrapping the roll packing material  24  around the mandrel  12 . Due to the expanded cleats  22  of the mandrel  12 , the roll packing material  32  assumes a multi-segmented form comprising multiple linear segments  36 . The number of linear segments  36  depends on the number of rows of cleats  22  around the circumference of the mandrel  12 . In this manner, the roll packing material  24  preferably does not directly contact the outer surface  18  of the mandrel  12 , although it may do so without departing from the spirit of this invention.  
         [0040]    Referring to FIGS. 3 and 3A, a sheet of corrugated material  38  supported by the feed table  28  is fed into the nip  36 . The mandrel  12  is further rotated, thereby wrapping the corrugated material  38  around the mandrel  12 . Again, due to the expanded cleats  22  of the mandrel  12 , the corrugated material  38  forms a multi-segmented form like the roll packing material  24 . As illustrated in FIG. 3A, the sheet of corrugated material  38  has side edges  40  defining a width W of the sheet, end edges  42  defining the length L of the sheet  38  and flutes or corrugations  44  extending parallel the side edges  40  or longitudinally. The sheet of corrugated material  38  is preferably oriented such that the corrugations  44  are generally perpendicular to the rotational axis A of the mandrel  12 . However, the sheet of corrugated material  38  may be oriented in any other manner. When the sheet of corrugated material  38  is fed into the nip  36 , one of the end edges  42  is introduced or fed into the nip  36  first.  
         [0041]    As shown in FIG. 4, the next step in the process is further rotation of the mandrel  12  which causes the sheet of corrugated material  38  to wrap at least once around the mandrel  12 . The sheet of corrugated material  38  is then wrapped over itself in an overlapped portion  48  and secured to itself either by adhesive, staples or other fasteners, thereby creating a sleeve, core or shell  50 , shown in FIG. 5. Alternatively, the sheet of corrugated material  38  may be secured to the roll packing material  32  or the mandrel  12 . The corrugated sleeve  50  has sufficient rigidity to prevent the finished roll pack from imploding while being removed from the mandrel or thereafter. As mentioned above, the present invention may also be practiced with non-corrugated material. Alternatively, the sleeve, core or shell  50  may be formed around the mandrel prior to the roll packing material  32  being wrapped around the mandrel. In this situation, the roll packing material  32  could be secured to the sleeve, core or shell  50  before further rotation of the mandrel wraps the roll packing material  32  around the sleeve  50 .  
         [0042]    [0042]FIG. 5 illustrates the step of feeding a compressible material, in this case a spring assembly  14  into the nip  36  between one of the compression rollers  24  and the mandrel  12  which is at this point surrounded with the corrugated shell  50 . At the same time the compressible material  14  is being fed to the mandrel  12 , the roll packing material  32  is being fed to the mandrel  12  underneath the compressible material  14 . As shown in FIG. 6, the compressible material  14  is compressed as it passes between the compression rollers  24  and the mandrel  12 .  
         [0043]    [0043]FIG. 7 illustrates the step of stopping the compressible material  14  from being fed into the nip  36 . Although the compressible material  14  is no longer being fed to the mandrel  12 , the roll packing material  32  is being fed to the mandrel  12  at least one revolution around the mandrel. As shown in FIG. 8, the roll packing material  32  is cut with a knife or other suitable apparatus  52  and secured in order to contain the compressible material  14 . The finished roll  54  is taken off the mandrel  12  as designated by arrow  53  in a manner such as that disclosed in U.S. patent application Ser. No. 10/066,905 once the cleats  22  of the mandrel  12  are moved to the collapsed position shown in FIG. 9B. However, the finished roll  54  may be removed from the mandrel  12  in any manner.  
         [0044]    [0044]FIGS. 10-15 illustrate another preferred embodiment of the method of the present invention. Referring to FIG. 10, a supply roll  30  of roll packing material  32  such as paper is provided. The roll packing material  32  may alternatively be stacked or stored in other manner without departing from the spirit of the present invention. The roll packaging material  32  is wrapped around guide rollers  34  and attached to the outer surface  18  of the mandrel  12  in any suitable manner. The retractable cleats  22  of the mandrel  12  are extended in the expanded position.  
         [0045]    Referring to FIG. 11, a dispensing apparatus  56  deposits adhesive or any other laminating material upon the roll packing material so that as the mandrel  12  is rotated, the roll packing material  24  is wrapped around the mandrel  12 , the adhesive being sandwiched between layers of roll packing material. Due to the expanded cleats  22  of the mandrel  12 , the roll packing material  24  assumes a multi-segmented form comprising multiple linear segments  36 . The number of linear segments  36  depends on the number of rows of cleats  22  around the circumference of the mandrel  12 . In this manner, the roll packing material  32  preferably does not directly contact the outer surface  18  of the mandrel  12 , although it may do so.  
         [0046]    Referring to FIGS. 12 and 13, the mandrel  12  is further rotated, thereby wrapping the roll packing material  32  around the mandrel  12 . Again, due to the expanded cleats  22  of the mandrel  12 , the roll packing material  32  forms a multi-segmented form. As shown in FIG. 12, the application of adhesive continues as the mandrel  12  is further rotated around the mandrel  12 . The adhesive between the layers of roll packing material  32  is then allowed to dry or cure, thereby creating a core or shell  58 , shown in FIG. 12. As shown in FIG. 13, the application of adhesive is stopped at a point, although the roll packing material  32  continues to be wrapped around the mandrel  12  upon further rotation of the mandrel.  
         [0047]    [0047]FIG. 13 illustrates the step of feeding a compressible material, in this case a spring assembly  14  into the nip  36  between one of the compression rollers  24  and the mandrel  12  which is at this point surrounded with the protective sleeve, core or shell  58 . The sleeve  58  is a laminated sleeve in this embodiment of the present invention and has sufficient rigidity to prevent the finished roll pack from imploding while being removed from the mandrel or thereafter. At the same time the compressible material  14  is being fed to the mandrel  12 , the roll packing material  32  is being fed to the mandrel  12  underneath the compressible material  14 . As shown in FIG. 14, the compressible material  14  is compressed as it passes between the compression rollers  24  and the mandrel  12 .  
         [0048]    Once the desired roll size is achieved, the compressible material  14  is no longer fed into the nip  36 . Although the compressible material  14  is no longer being fed to the mandrel  12 , the roll packing material  32  may be being fed to the mandrel  12  at least one revolution around the mandrel. As shown in FIG. 15, the roll packing material  32  is cut with a knife or other suitable apparatus  52  and secured in order to contain the compressible material  14 . The finished roll  54  is taken off the mandrel  12  as designated by arrow  53  in a manner such as that disclosed in U.S. patent application Ser. No. 10/066,905 once the cleats  22  of the mandrel  12  are moved to the collapsed position shown in FIG. 9B. However, the finished roll  54  may be removed from the mandrel  12  in any manner.  
         [0049]    While the present invention has been illustrated by the description of several preferred embodiments thereof, and while each embodiment has been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. For example, the sleeve or core of the roll may be formed of any suitable material. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of applicant&#39;s general inventive concept.