Abstract:
A method of applying at least one web of insulator material to a plurality of spring assemblies is provided. Each web of insulator material is unwound from a roll, passed along a roller and applied to multiple spring assemblies which are passed between rollers. Each web of insulator material is folded around outermost coil springs along longitudinal edges of the spring assemblies. Side portions of each web of insulator material are glued, welded or otherwise permanently secured to a middle portion of the web of insulator material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation-in-part application of U.S. patent application Ser. No. 10/143,377 filed May 10, 2002 entitled METHOD OF PACKAGING SPRING UNITS “, now abandoned” U.S. patent application Ser. No. 10/143,377 is a continuation-in-part application of U.S. patent application Ser. No. 10/034,823 filed Dec. 27, 2001, now U.S. Pat. No. 6,467,239, entitled METHOD OF PACKAGING SPRING UNITS, which is a continuation-in-part application of U.S. patent application Ser. No. 09/712,503 filed Nov. 14, 2000, entitled METHOD OF PACKAGING SPRING UNITS, now abandoned. U.S. patent application Ser. No. 09/712,503 is a continuation-in-part application of U.S. patent application Ser. No. 09/397,337, filed Sep. 15, 1999, entitled “METHOD OF PACKAGING SPRINGS AND RESULTING PACKAGED PRODUCT”, now abandoned. All of the above-identified applications are fully incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to the process of securing at least one web of insulator material to multiple spring assemblies. 
     BACKGROUND OF THE INVENTION 
     At the present time, most mattress spring core assemblies are manufactured by a spring manufacturer who assembles the springs into a spring assembly. To save space and therefore reduce shipping costs, the spring manufacturer compresses multiple spring assemblies and ties them in a crate. The crates are shipped to a mattress manufacturer, who then uncrates the compressed spring cores, applies a primary insulator to the top and bottom surfaces of the mattress, and then applies conventional padding and upholstery to complete the mattress. In order to keep the mattress spring assemblies straight and avoid the mattresses top and bottom surfaces being permanently canted and distorted as the spring assemblies are compressed for shipment in a crate, there are rods inserted through the spring assemblies during the compression process. These rods function to prevent misalignment of the top and bottom surfaces of the spring assemblies during compression, which rods are then removed after compression and during shipment within the crate. 
     As an alternative to compression of the spring assemblies for shipment in crates, some spring assemblies are compressed and roll-packed while sandwiched only between separator plies of paper or plastic, which paper or plastic may be either discarded or reused, depending on the nature of the separating materials. 
     For instance, it is known in the art to roll-pack multiple spring assemblies or units for use in making mattresses by winding disposable paper or re-usable hessian around a mandrel and feeding the spring units successively into the nip between the growing roll and the traveling web material. The spring units are compressed as they are drawn into the roll, and the result is that the roll-packed spring assemblies have a much reduced volume as compared to conventionally stacked spring units. 
     Prior art roll packing machines compress and wrap spring assemblies in a single web of disposable paper or reusable material which separates the multiple layers of spring assemblies in a roll and maintains the spring assemblies in a compressed state for shipment from a spring manufacturer to a mattress manufacturer. The mattress manufacturer then must unroll the spring units and manually attach an insulator pad to at least the top and usually the top and bottom surfaces of each spring unit before adding conventional padding and upholstery to the unit to complete the mattress. The insulator pads prevent the conventional filling materials such as padding from falling between the wire gaps in the spring assembly. The manual application of these insulator pads is time consuming and costly because it requires an operator manually securing the insulator pads to the spring assemblies with hog rings or other fasteners. 
     Applicant&#39;s U.S. Pat. No. 6,357,209, which is fully incorporated by reference herein, discloses a method of packaging spring units in which at least one layer of insulator material is permanently secured to multiple spring units before the spring units and insulator material are roll packed. The roll packed bedding products are then shipped in a roll to a mattress manufacturer who unrolls them and applies padding or other filling materials before encased each spring unit in a fabric covering. 
     However, in certain circumstances, a mattress manufacturer may receive a roll of roll packed spring assemblies which do not have any webs of insulator material attached thereto. In such a situation, the mattress manufacturer must unroll the roll packed spring assemblies and subsequently apply at least one web of insulator material to each spring assembly before padding and/or filling materials are added and the product encased in fabric. Heretofore, this process has been manual, an operator hog ringing or otherwise securing at least one web of insulator material individually to each spring assembly. This manual application of the insulator pads is time consuming and costly because among other things, this process requires a skilled, trained operator. 
     Therefore, it has been one objective of the present invention to provide an automated method of quickly and easily securing at least one web of insulator material to multiple spring assemblies. 
     It has been a further objective of the present invention to facilitate and ease the manufacture of spring mattresses by a mattress manufacturer. 
     SUMMARY OF THE INVENTION 
     The present invention accomplishes these objectives with a method of applying at least one web of insulator material to multiple spring assemblies. Each spring assembly preferably comprises a plurality of interconnected coil springs. Each of the coil springs has an upper end turn, a lower end turn and a plurality of central convolutions therebetween, as is conventional. However, other types of springs including continuous bands of coil springs may be incorporated into the spring assembly in accordance with the present invention. 
     The method of the invention allows at least one web of spring insulator material to be secured or attached to a plurality of spring units or spring assemblies in an automated manner so as eliminate the need for an operator. The process of the present invention enables a mattress manufacturer to unroll multiple spring assemblies from a roll of roll-packed spring assemblies and feed them one at a time into a space or nip between guide rollers. Any type of unroller may be used in accordance with the present invention. Alternatively, the mattress manufacture may uncrate a crate of compressed spring assemblies and feed the spring assemblies one at a time into the nip one at a time for application of the web or webs of insulator material thereto. 
     The nip or distance between the guide rollers is preferably slightly less than the height of the spring assemblies so that each spring assembly which passes therebetween is slightly compressed. The result of the slight compression is that when each web of insulator material is applied, it becomes taught on the top or bottom surface of the spring assembly. 
     Each spring assembly preferably has a uniform depth defined by a generally planar top first surface and a parallel generally planar bottom second surface. The spring assembly has a longitudinal dimension or length defined by a pair of opposed parallel end surfaces and a transverse dimension or width defined by a pair of opposed parallel side surfaces. The longitudinal dimension or length is generally greater than the transverse dimension or width of the spring assembly as in most bedding products. However, a square spring assembly in which the longitudinal and transverse dimensions are equal may also have one or more webs of insulator material applied thereto using this inventive method. 
     The method of the present invention comprises feeding or introducing spring assemblies into a space or nip between a pair of guide rollers spaced from one another. The spring assemblies are preferably oriented with the longitudinal dimension of the spring assembly parallel the direction of travel so that a leading end surface of the spring assembly is first introduced between the guide rollers. However, the spring assemblies may be oriented in any manner without departing from the spirit of the present invention. 
     First and second web rolls of insulator material are preferably provided generally above and below the spring assemblies, respectively. The first web roll comprises a first web of spring insulator material, e.g., bonded fiber or non-woven fiber or other web material, wound about a core. Similarly, the second web roll comprises a second web of similar spring insulator material wound about a core. However, the webs of insulator material may be stored in other ways and at other locations. Each of the first and second webs of insulator material have a pair of opposed side edges defining a width of the web which is wider than the spring assemblies&#39; transverse dimension. Each web across its width has a pair of opposed side portions and a central portion between the side portions. 
     The first and second webs of insulator material are each passed over a guide roller and located against the first and second surfaces of the spring assembly, respectively. The longitudinal dimension of the spring assembly is preferably parallel to the opposed side edges of the first and second webs of insulator material. However, the spring assemblies may be oriented such that the transverse dimension of the spring assembly is generally parallel to the opposed side edges of the first and second webs of insulator material. 
     Either before, during or after the process of being wound around a respective guide roller, a bonding material is applied to the inner surface of each of the side portions of each web of insulator material. The bonding material is preferably adhesive but may be other material such as, for example, a molten plastic material. The bonding material may be extruded or otherwise applied to the inner surfaces of the webs of insulator material. 
     The next step in the method of the present invention is to fold each of the webs of insulator material back upon itself around the top and bottom turns of the edgemost coil springs of the spring unit, respectively, so that the inner surfaces of the opposed side portions of each web of insulator material are located against the inner surface of the central portion of the web of insulator material. This central portion of each web of insulator material is located against either the top or bottom surface of the spring assembly. The bonding material is then allowed to dry, thereby securing the side portions of each web of insulator material to the central portion of the web of insulator material with the end turns of the coil springs trapped therebetween. In this manner, each web of insulator material is secured to the spring assembly. 
     In an alternative embodiment of the method of the present invention, the web or webs of insulator material may be secured to the spring assemblies after being folded. In this embodiment of the present invention, the side portions of each web of insulator material are welded, sewn or otherwise secured to the central portion of the web of insulator material at a securement station which is “downstream” of the location where the web or webs of insulator material are folded around the outermost end turns of the spring assemblies. Thus, in this embodiment the side portions of each web of insulator material are secured to the central portion of the web of insulator material after the web of insulator material is folded. 
     The final step in the method of the present invention is to cut the web or webs of insulator material between adjacent spring assemblies. 
     The spring assembly with the first and second webs of insulator material secured thereagainst constitutes a bedding or seating product to which padding may be subsequently applied before the product is encased in a covering. The web or webs of insulator material prevent the padding from falling between the wire gaps of the spring assembly. 
     These and other objectives and advantages of this invention will be readily apparent from the following description of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the present inventive method of applying webs of insulator material to a resilient spring assembly; 
         FIG. 2  is a perspective view of a method of applying webs of insulator material to a spring assembly after the spring assembly has been unrolled from a roll pack; 
         FIG. 3  is a cross-sectional view taken along line  3 — 3  of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings and particularly  FIG. 1 , a spring assembly  10  having a top or first surface  12  and a bottom or second surface  14  is illustrated. The spring assembly  10  has a length or a longitudinal dimension L defined as the distance between opposing end surfaces  16  and a width or a transverse dimension D defined as the distance between opposing side surfaces  18 . Typically, the longitudinal dimension L is larger than the transverse dimension D; however, it will be appreciated by those in the art that the length and width may be substantially similar. The spring assembly  10  has a thickness T between the first surface  12  and the second surface  14 . 
     The spring assembly  10  is generally comprised of a plurality of coil springs  20 , the coil springs  20  being secured one to another by means generally known in the art, such as helical lacing wires (not shown), for example. At least one border wire  21  may surround the assembled springs  20 . As best illustrated in  FIG. 3 , each coil spring  20  has a top turn  22  comprising a portion of the first surface  12 , a bottom turn  24  comprising a portion of the second surface  14  and a plurality of central convolutions  26  therebetween. Springs other than coil springs may be used in accordance with the present invention. In addition, springs of differing heights may be used in accordance with the present invention. 
     As illustrated in  FIGS. 1 and 2 , first and second webs of insulator material  28 ,  30  are wound about first and second cores  32 ,  34  into web rolls  35 ,  36 , respectively. The first and second webs of insulator material  28 ,  30  may be unrolled therefrom in directions as indicated by directional arrows  37 ,  38 , respectively. The first and second webs of insulator material  28 ,  30  are drawn between respective first and second guide rollers  40 ,  42 . Preferably, guide rollers  40 ,  42  are spaced apart from each other so that spring assembly  10  may be slightly compressed when passed therebetween. A space or nip  44  is defined between the first and second guide rollers  40 ,  42 . The guide rollers  40 ,  42  may be spaced such that the spring assemblies  10  passed therebetween are slightly compressed or not compressed at all. 
     Each of the first and second webs of insulator material  28 ,  30  has an inner surface  46  and an outer surface  48 . As the first and second webs of insulator material  28 ,  30  are passed around the guide rollers  40 ,  42 , the outer surfaces  48  of the first and second webs of insulator material  28 ,  30  contact the guide rollers  40 ,  42 . After the first and second webs of insulator material  28 ,  30  are secured to the spring assembly  10 , the inner surfaces  46  of the first and second webs of insulator material  28 ,  30  are located against the first and second surfaces  12 ,  14  of the spring assembly  10 . 
     As best illustrated in  FIG. 3 , the first web of insulator material  28  has a pair of side edges  50  between which is a center portion  52  and opposed side portions  54 . Similarly, the second web of insulator material  30  has a pair of side edges  56  between which is center portion  58  and opposed side portions  60 . Each of the first and second webs of insulator material  28 ,  30  has a substantially similar width W defined as the distance between the side edges  50 ,  56 , respectively. See  FIG. 1 . The width W of each web of insulator material is larger than the transverse dimension D of the spring assembly  10  so that the opposed side portions  54 ,  60  of the first and second webs of insulator material  28 ,  30 , respectively generally extend beyond the transverse dimension D of the spring assembly  10  in substantially equal amounts. The lengths (not indicated) of the first and second webs of insulator material  28 ,  30  are considerably longer than the longitudinal dimension L of a single spring assembly  10  so that the webs of insulator material  28 ,  30  may be applied to plural spring assemblies  10  by the inventive method described in further detail below. 
     Referring to  FIG. 1 , the method of the present invention comprises first introducing or feeding the spring assembly  10  into the nip  44  between guide rollers  40 ,  42  in the direction of arrow  61 . The spring assembly  10  is oriented such that the side surfaces  18  of the spring assembly  10  are generally parallel the side edges  50 ,  56  of the first and second webs of insulator material  28 ,  30 . However, the spring assembly  10  may be oriented in other directions, such as for example with the end surfaces  16  of the spring assembly  10  generally parallel the side edges  50 ,  56  of the first and second webs of insulator material  28 ,  30 , respectively. 
     As illustrated in  FIG. 1 , each spring assembly  10  is introduced or fed into the nip  44  between guide rollers  40 ,  42  in the direction of arrow  61  one at a time. The spring assemblies may be unrolled from a roll of roll-packed spring assemblies as illustrated in  FIG. 1A  and described below, removed from a crate of compressed spring assemblies or unpacked any other way before being introduced one spring assembly  10  at a time into the nip  44  between guide rollers  40 ,  42 . 
     The webs of insulator material  28 ,  30  are unwound or unrolled from web rolls of insulator material  35 ,  36 . Alternatively, the webs of insulator material may be unpackaged from a stack or pile or any other storage device or configuration. The webs of insulator material  28 ,  30  are passed around guide rollers  40 ,  42  before being located against the first and second surfaces  12 ,  14 , respectively, of the spring assembly  10 . 
     As illustrated in  FIG. 1 , either before, after or while the first and second webs of insulator material  26 ,  28  are passed around guide rollers  40 ,  42 , applicators  62  deposit a bonding material  64  such as adhesive against the inner surface  46  of the side portions  54  of the first web of insulator material  26 . Although  FIG. 1  illustrates the applicators  62  being located above the first web of insulator material  28 , they may be located elsewhere without departing from the spirit of this invention. Similarly, either before, after or while the second web  30  of insulator material is passed around guide roller  42  applicators  66  deposit a bonding material  68  such as adhesive against the inner surface  46  of the side portions  60  of the second web of insulator material  30 . Although  FIG. 1  illustrates the applicators  66  being located generally in front of the guide roller  42 , they may be located elsewhere without departing from the spirit of this invention. 
     The spring assembly  10  having the first and second webs of insulator material  28 ,  30  located thereagainst is then passed to a folding unit  70  which folds the side portions  54 ,  60  of each of the first and second webs of insulator material  28 ,  30  around the end turns of the outer coil springs  20 . More particularly, the inner surface  46  of the side portions  541   60  of each of the first and second webs  28 ,  30  with the bonding agent  64 ,  68  deposited thereon are folded around the upper and lower end turns  22 ,  24  of the outermost coil springs  20  before being pressed against the inner surfaces  46  of the respective center portions  52 ,  58 . The top and bottom end turns  22 ,  24  of the coil springs  20  comprising the longitudinal margins of the spring assembly  10  are trapped between the side portions and center portions of the first and second webs of insulator material  28 ,  30 . In this manner the first and second webs of insulator material  28 ,  30  are secured to the coil springs  20  of the spring assembly  10 . 
     The bonding agent is then allowed to dry such that the bonding agent secures the side portions  54 ,  60  of the first and second webs of insulator material  28 ,  30  to the center portions  52 ,  58  of the first and second webs of insulator material  28 ,  30 . 
     As illustrated in  FIGS. 1 and 2 , an alternative embodiment of the present invention is illustrated. In this embodiment, the first and second webs of insulator material  28 ,  30  are secured to the spring assemblies  10  at a securement station  84  (shown in dashed lines). In this embodiment, the side portions  54 ,  60  of the first and second webs of insulator material  28 ,  30  are secured to the center portions  52 ,  58 , respectively at the securement station  84  using any of numerous method including but not limited to sewing or ultasonic welding. The welding together of the side and center portions of each of the first and second webs of insulator material  28 ,  30  may be accomplished by any suitable welding process for woven or non-woven materials known in the art, e.g., ultrasonic or radio frequency welding, to create a weld or bond. In this embodiment, the applicators  62 ,  66  may not be activated or may be omitted entirely. 
     The insulator material used to cover the first and second surfaces  12 ,  14  of the spring unit  10  is generally a woven or non-woven material but may be any other flexible sheet of web material. 
     In one preferred embodiment, after the bonding agent drys, the first and second surfaces  12  of the spring assemblies  10  are covered with the webs  28 ,  30  of insulator material. After the webs of insulator material  28 ,  30  have been fixedly located against the first and second surfaces  12 ,  14  of the spring unit  10  by either the gluing or the welding methods as described above or any other conventional securement method, the spring assemblies  10  with the first and second webs of insulator material  26 ,  28  located there against are then passed to a cutter  70  which transversely cuts in a direction  72  the webs of insulator material  28 ,  30  at locations between adjacent, spaced spring assemblies  10 . 
     The spring assembly  10  with the first and second webs of insulator material  28 ,  30  attached permanently thereto comprises a bedding or seating product  74  ready for shipment, for example, from a spring manufacturer to a mattress or seat manufacturer. 
     When the bedding or seating products  72  arrive at the mattress or seat manufacturer&#39;s facility, all that the manufacturer need do is unpack the products  72  and apply the necessary padding and upholstery material. The resulting bedding or seating product  72  having the insulator material permanently secured to its top and bottom sides is than ready for application of the appropriate padding and upholstery materials to complete the mattress or seat. 
       FIG. 2  illustrates an alternative embodiment of the present invention. In this embodiment, the method includes a step of unrolling a plurality of spring assemblies  10   a  from a roll  76  of compressed spring assemblies  10   a . Within the roll  76  of compressed spring assemblies  10   a , separator material  78  is wound about a core  80  as the roll  76  of compressed spring assemblies  10   a  is being unrolled. Either after the spring assemblies  10   a  are unrolled or while the spring assemblies  10   a  are being unrolled, the spring assemblies  10   a  are moved, one at a time, in the direction of arrows  82  into the nip  44  between the guide rollers  40 ,  42 . 
     From the above disclosure of the detailed description of the present invention and the preceding summary of the preferred embodiment, those skilled in the art will comprehend the various modifications to which the present invention is susceptible. Therefore, I desire to be limited only by the scope of the following claims and equivalents thereof.