Abstract:
The invention described in the specification relates to a heavy bag for use in training a boxer and to a method for filling the bag. The bag has a substantially cylindrical outer shell made from a fabric-like material, the shell having closed ends. A shredded rubber material fills the bag and provides the bag with sufficient weight for punching and sparring training activities. Use of the shredded rubber material to fill the bag not only permits significant improvement in the bag filling operation but also provides increased durability, improved impact absorbing characteristics and less permanent deformation of the bag during use.

Description:
The invention relates to a heavy boxing bag apparatus and to an improved method for filling heavy boxing bags. 
     BACKGROUND 
     Conventional heavy bags used for training for boxing and sparring are typically filled with shredded fabric or paper, polyester batting, jute, sawdust or other light weight shredded materials and have sand bags interspersed in the fill material to provide the desired bag weight so that when the boxer punches the bag, the feel experienced by the boxer resembles that of punching another boxer. Such bags are typically filled by hand with careful placement of the sand bags to distribute the weight evenly within the bag and to prevent misshapened bags or bags which do not provide the proper impact-absorbing function upon being struck or punched. 
     Heavy bags may weigh from 25 to 100 pounds or more depending on the size and use of the bag. Smaller bags require less weight and thus fewer sand bags while larger bags typically require more weight and thus more sand bags. Because not all bags are manufactured to the have the same weight, production of a variety of bag sizes and bags having different weights is a time consuming, often manpower intensive operation which does not readily lend itself to automation. 
     Another disadvantage of conventional heavy bags is that they often lose there shape over time as a result of repeatedly punching the same area of the bag. Punching the bag causes movement of the shredded fabric or paper, polyester batting, jute, sawdust and/or sand bags within the bag. Reshaping of a misshapen bag requires the bag be opened and the fill material and sand bags be redistributed or repacked within the bag. Unless the fill material is redistributed periodically, damage to the bag may occur from repeated punching of the bag after the material has shifted. 
     An object of the invention is to provide an improved heavy bag for boxing and sparring training. 
     Another object of the invention is to provide a heavy bag which will maintain its shape substantially longer than conventional heavy bags. 
     A further object of the invention is to provide a method for filling a heavy bag used for boxing and sparring training activities. 
     Still another object of the invention is to provide a heavy bag having a weighting material therein which is may be used to fill a variety of heavy bags with a minimum of manpower. 
     Yet another object of the invention is to provide a heavy bag that has a feel which more closely resembles the feel of punching a human being. 
     Another object of the invention is to improve the performance and durability of a heavy bag. 
     A still further object of the invention is to provide a heavy bag of the character described which economical to manufacture. 
     SUMMARY OF THE INVENTION 
     With regard to the above and other objects, the invention provides a heavy bag for boxing and sparring training including a natural or synthetic fabric web having a substantially cylindrical shape and having opposed closed ends which defines a closed chamber containing pellets or granules of rubber which substantially fill the chamber. 
     In another aspect the invention provides a method for filling a heavy bag used for boxing or sparring training activities. The method includes forming a chamber having substantially cylindrical walls made from a resilient web-like material wherein the chamber has a closed end and an open end, loading the chamber through the open end with a rubber material in granular or pellet form and closing the open end to provide a substantially filled heavy bag. 
     An advantage of the heavy bag loaded with a rubber material as described herein is that the bag maintains its shape substantially longer and provides a more realistic feel when punched or struck as compared to conventional bags filled with shredded fabric, sawdust or jute and weighted with sand bags. Furthermore, the rubber material is easier to handle and loading a bag with such material may be conducted more quickly and with substantially less manpower than filling and packing a conventional heavy bag. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other benefits and advantages of the invention will be evident from the drawings in conjunction with the following description in which: 
     FIG. 1 is an elevational view of a heavy bag according to the invention; 
     FIG. 2 is a cross-sectional view not to scale of a heavy bag showing a preferred construction thereof; and 
     FIG. 3 is a simplified illustration of a preferred method for filling a heavy bag according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, there is provided a heavy bag  10  for use in boxing and sparring training activities. The bag  10  includes a substantially cylindrical fabric shell, sleeve or outer layer  12  preferably provided by a natural or synthetic web-like or fabric material such as canvas, nylon, polyester, leather and the like having a closed end  14  opposite a closeable end  16  defining a chamber therein. The closed and closeable ends may be made out of the same or different material as the shell  12 . End  16  may be closed after filling the bag as by closure device  18  such as a zipper, hook and loop fastener, snaps, buttons or by sewing a portion of end  16  to an adjacent portion of shell  12 . Closed end  14  may be permanently or temporarily attached to the shell  12  by use of devices similar to the devices used to close closeable end  16 . 
     Heavy bags are typically suspended from a hook or other support device so that they hang freely. Thus, suspension straps  20  and support ring  22  may be provided for use in suspending the bag from a support such as a ceiling or cantilevered frame. Additional straps may be attached adjacent closed end  14  of the bag if desired to prevent the bag from swinging too far or to reduce the tendency of the bag to swing when struck or punched. It will also be recognized that the bag may be also suspended horizontally by attaching the suspension straps  20  to ends  14  and  18  of the bag  10  or to a central portion of the cylindrical surface of the bag. The orientation of the bag in use is not important to the invention. 
     A unique feature of the heavy bag according to the invention is the use of a resilient, substantially free-flowing granular or pellet material as a impact absorbing material which substantially fills the bag  10 . The granular or pellet material is preferably a shredded rubber material having a density ranging from about 20 to about 35 pounds per cubic foot and having an average size of from about 1 to about 10 mm in the longest dimension. A preferred source of shredded rubber material is shredded tires, however, any shredded rubber material and preferably those having the size and density described above may be used to load the bag. Recycled, shredded rubber material which may be used to fill the bag is available from rubber recycling sources such as NRI of Easton, Md. 
     FIG. 2 provides a cross-sectional view of a heavy bag  10  according to the invention showing the shredded rubber material  24  within the bag. The outer shell  12  is preferably provided by a web-like material having a substantially cylindrical shape. In order to soften the impact exerted by a boxer on the bag, it is preferred to line substantially all of the inner surface of the shell  12  with a foam pad  26 . The foam pad  26  may be an open cell polyurethane foam, a closed cell polyethylene foam or any other padding or cushing material conventionally used to provide a resilient impact surface which is softer than the material used to fill the bag. 
     A preferred foam pad  26  has a thickness ranging from about 0.25 to about 4 inches or more depending on the diameter of the bag. For heavy bags having weights ranging from 25 to about 100 pounds, a pad having a thickness ranging from about 0.5 to about 1.5 inches is preferable. 
     Between the foam pad  26  and the fill material  24  there is preferably placed a barrier  28 . The barrier  28  is preferably composed of a substantially air impermeable material such as heavy weight paper or paperboard. The weight of paper or paperboard used for barrier  28  is not critical to the invention but will typically have a caliper ranging from about 10 to about 40 thousands of an inch (about 10 to about 40 point board) available from Accurate Paper Box Company, Inc. of Knoxville, Tenn. Other air impermeable materials may be used for the barrier  28  such as plastic films, molded plastic sheets, and the like. It is preferred that the barrier  28  be sufficiently rigid so as to be substantially self-supporting in order to maintain the pad  26  and shell  12  in a substantially upright position while the bag is being loaded with shredded rubber  24 . 
     Once the bag has been loaded, a packing stuffer pad  30  is used to maintain the shredded rubber in a closely packed configuration so that the bag substantially maintains its shape. The stuffer pad  30  may be made of a variety of materials which may be compressed but which resiliently returns to its shape when the compression force is removed. A suitable stuffer pad  30  is an open cell polyurethane foam. Other materials which may be used to provide the stuffer pad  30  include closed cell foams such as polyethylene foam or any other resiliently compressible material. 
     A preferred stuffer pad  30  has a thickness of about  4  inches, however thicknesses of from about 2 to about 6 inches or more may be used to compress the fill material in order to maintain the fill material in its closely packed orientation. The weight of the bag may be adjusted by using more or less fill material  24 , higher or lower density fill material and a thicker or thinner stuffer pad  30  for a selected heavy bag size. 
     A distinct advantage obtained by using shredded rubber fill material  24  of the size and density described above to load and weight a heavy bag  10  is that shredded rubber provides an impact absorbing effect and a sufficient weight to the bag and yields a bag having improved punching characteristics as compared to conventional heavy bags. Accordingly, there is no need to add additional weight to the bag with sand bags or similar ballast or weighting materials. Furthermore, because the shredded rubber as described herein is substantially free-flowing, there is less tendency for the bag to be misshapened or damaged over time. If the bag becomes misshapen on one side due to punching or striking the same spot, striking the opposite side of the bag will cause movement of the shredded rubber within the bag so that the bag is reshaped by use rather than by opening the bag and redistributing the packing material by hand. The sleeve or fabric shell  12  and packing stuffer  30  also maintain the shredded rubber in a closely packed configuration so that the bag simulates a human body when punched or struck. 
     Referring now to FIG. 3, there is illustrated a preferred method for loading heavy bags  10  according to the invention. In the method, a source of shredded rubber  32  is provided. The shredded rubber is transferred to the heavy bag by means of a transfer device  34 . The transfer device  34  may be a conventional grain auger or a pneumatic conveyor or any other granular or pellet material transfer device known by those of ordinary skill to be useful for transferring such free-flowing materials from one location to another. In the alternative, the bag may be filled by gravity from an overhead source of shredded rubber fill material. The shredded rubber is preferably sufficiently free-flowing so as to promote the loading of heavy bags with a minimum of effort. 
     Use of a loading device  34  such as a grain auger or pneumatic transfer unit enables a heavy bag  10  to be loaded with the shredded rubber  24  in a matter of a few seconds as opposed to hand packing a heavy bag with shredded cloth, etc. and sand bags which may take a substantially longer amount of time. Accordingly, the use of shredded rubber fill material as a weighting and fill material for a heavy bag significantly decreases the time and manpower previously required to load a heavy bag with conventional materials. 
     During the loading operation, end  16  of the bag  10  is opened and a nozzle  36  having a flexible spout  38  is positioned over the bag  10  so that shredded rubber material  24  will be directed into the bag to substantially fill the bag. Once the nozzle  36 , spout  38  and bag  10  are properly positioned, the loading operation can begin. In the case where a grain auger is used as the loading device  34 , the motor  40  of the auger is turned on to fill the auger  34 , nozzle  36  and spout  38  with shredded rubber material from source  32 . The motor is connected either directly to the auger shaft  42  or indirectly by means of pulleys  44  and  46  and belt  48 . 
     When a sufficient amount of shredded rubber material has been transferred into the bag  10 , the motor  40  of the auger is turned off and the bag is closed by attaching end  16  to shell  12  using a zipper or other closure device. Prior to closing the bag, a foam pad  30  (FIG. 1) as described above is inserted over the fill material  24 . The foam pad  30  is preferably slightly compressed over the fill material  24  by end  16  so that the pad  30  maintains the fill material in a closely packed orientation in order to provide a heavy bag  10  having a suitable impact absorbing effect. 
     Having described and illustrated various aspects and embodiments of the invention, it will be appreciated that many modifications, rearrangements, additions, improvements and substitutions may be made to these embodiments by those of ordinary skill all of which are nevertheless within the spirit and scope of the invention as defined in the appended claims.