Patent Publication Number: US-2012046137-A1

Title: Baseball bat employing a dual density foam material

Description:
FIELD OF THE INVENTION 
     The present invention is generally related to the field of baseball and softball and more specifically to a baseball or softball bat. 
     BACKGROUND OF THE INVENTION 
     Baseball and softball players continually search for better bats to improve their hitting performance. Bat performance is generally based upon length, weight, moment of inertia (MOI) and impact response during contact with the ball. Manufacturers have made attempts to improve the impact response during contact with the ball using a variety of material construction. Unfortunately, each of these prior attempts has various shortcomings. 
     A s manufacturers have improved bats, various regulatory bodies and administrators of organized baseball and softball games have placed restrictions on bat performance and configuration. In order to limit the maximum response to the bat, manufacturers have traditionally modified their designs to dampen the response to all impacts. In other words, these designs reduce the responsiveness of the bat at both low impact speeds as well as high impact speeds. Typically this is done by adding material to the thickness of the barrel portion of the bat to increase the hoop of stiffness. This approach hinders the hitting performance of less skilled players in an effort to control the maximum rebound speed generated by the best players. 
     Bat rebound performance is generally maximized at a narrow width of the barrel commonly referred to as the sweet spot. The prior art includes several attempts to produce a bat with reduced performance at the sweet spot. The intent of these designs has been to level the impact response along. the width of the barrel, effectively widening the perceived sweet spot. These attempts have several shortfalls. For example, U.S. Pat. No. 6,949,038, issued to Fritzke, discloses increasing in the wall thickness of the bat near the sweet spot. This is accomplished, for example, by including an insert  22 , as illustrated in  FIG. 4 , having first and second tubular wall transition regions  36  and  38 , as well as an intermediate tubular region  40 , having an increased thickness. Additionally, as illustrated with respect to  FIG. 7 , an intermediate tubular region  140  provided on the outside surface of the bat would also have an increased thickness. As can be appreciated, the added thickness of the insert or the outer portion of the bat would add additional weight and create stress concentrations at each end of the thicker regions. 
     Consequently, there is a need to provide an improved bat which would meet regulation standards for maximum barrel response with less dampening at slower speed impacts. 
     Additionally, there is a need to produce a bat having a more consistent impact response along the length of the barrel than conventional bats without the increased weight or the creation of stress concentrations, as described in prior art references. 
     Baseball bats are generally constructed having a barrel portion, a tapered portion and a handle portion. Recently, several U.S. patents have illustrated non-wood bats provided with a foam in the interior of the bat filling at least a portion of the barrel as well as perhaps a portion of the tapered portion. example, U.S. Pat. Nos. 6,248,032, 6,334,824 and 6,432,007, issued to Filice et al describe an aluminum shell bat including a foam filler  30  comprising a syntactic foam which substantially fills the interior of the bat shell  10  in the hitting area by filling the entire barrel of the bat as well as a portion of the tapered area. It is important to note that the foam filler  30  consists of only a single density material. 
     U.S. Pat. Nos. 5,458,330 and 5,533,723 both issued to Baum describe a composite baseball bat provided with a core in the barrel section. This baseball bat includes a layer of wood-like veneer covering a layer of fiber reinforced resin.  FIGS. 12 and 13  illustrate a bat having a core with a central cavity. As discussed in column 4, lines 18-30 of both patents, a core  28  is provided formed from a resilient urethane foam. It is noted that this core  28  extends around a plug  31  in the barrel portion of the bat as well as extending throughout the handle portion. As further described in column 5, lines 20-51 of the &#39;723 patent, the plug  31  is provided within the central cavity formed of a different and generally less dense material than the core  28 . Since the plug material  31  is less dense than the material of the core, the plug  31  would be more compressible than the core  28 . 
     U.S. Pat. No. 3,810,098 issued to Gildemeister discusses a metallic baseball bat including a hollow tube having a rigid urethane foam core  20  as well as a plug  15   a  comprised of a heavier foam than the core  20 . It is noted that the plug  15   a  does not surround the rigid urethane foam but is provided adjacent to the end cap portion of the bat. 
     U.S. Pat. No. 5,964,673 issued to MacKay, Jr. describes a hollow metallic bat containing one or more resilient sponge-like balls  26 . A hardenable material  28 , such as urethane or the like is provided around a portion of one of the balls as shown in  FIG. 4  or would completely surround a sponge ball as illustrated with respect to  FIG. 5 . 
     However, it has been found that the aforementioned designs would produce a bat in which the hitting performance of the less skilled players might be compromised in the effort to control the maximum rebound speed generated by the best players. 
     Consequently, a need has arisen in which the placement and type of foam materials particularly within the barrel portion of the bat would be crucial to elevating the performance of lesser players without hindering the performance of the better players. 
     SUMMARY OF THE INVENTION 
     The deficiencies of the prior art are addressed by the present invention in which a non-wood baseball or softball bat is produced utilizing an insert with a highly compressible outer foam layer which allows the bat frame to deflect within a limited range with minimal dampening of the vibrations produced when a ball strikes the outer surface of the baseball or softball bat. The prior art use of a single density material such as described in the aforementioned Felice patents would dampen even small deflections of the baseball bat frame. The present invention would allow a greater barrel response (commonly referred to as the “trampoline effect”) for lower speed impacts verses the prior art, while still limiting the maximum barrel response for higher speed impacts produced by the best players. This would allow the bat to meet the required safety standards by the various governing bodies, but still providing an improved hit performance for the less skilled players. 
     Additionally, the present invention is also an improvement of the prior art bats utilizing a dual density material such as described in the aforementioned Baum patents. As previously indicated, the Baum patents employ a core material formed from a resilient urethane foam which is denser and therefore less compressible than the plug material which it surrounds. This is in contradistinction to the present invention utilizing two separate foams of different density. A first foam material is provided in the interior of the bat extending from the end cap to approximately the beginning of the tapered portion of the bat. This material is surrounded by a thin layer of a foam material having a density less than the density of the inner foam material. Consequently, the thin outer layer of the foam is much more compressible than the inner foam layer. This particular configuration would provide for a better performance at low impact speeds than the prior art bats utilizing a single foam material. 
     These and other objects of the present invention will be explained in detail with respect to the following detailed description, when viewed with respect to the accompanying drawings, wherein like reference numerals refer to like parts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal cross-sectional drawing of a conventional hollow non-wooden bat; 
         FIG. 2  is a longitudinal cross-sectional drawing of a prior art bat having a single density foam filler; 
         FIG. 3  is a longitudinal cross-sectional drawing of a first embodiment of the present invention; 
         FIG. 4  is an enlarged cross-sectional drawing of the embodiment shown in  FIG. 3 ; and 
         FIG. 5  is a longitudinal cross-sectional drawing of a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
       FIG. 1  illustrates a typical hollow non-wood bat  10  generally consisting of a barrel portion  12  provided with an outer surface  14  which includes the primary hitting portion of the bat normally known as the sweet spot. The material of the outer surface  14  would be metallic, such as aluminum or titanium. Alternatively, the exterior surface of the bat can be constructed from a composite fiber material. A handle  22  is used by the player to properly grip the bat. A tapered portion  18  is provided between the barrel portion  12  and the handle  22 . The interior portion of the bat  16  is generally hollow and would extend from an end cap  20  through the barrel portion  12  to the tapered portion  18  and then to the handle portion  22 . 
     The prior art, such as discussed in the Filice patents would try to minimize impact induced vibrations by filling a portion of the interior of the bat with a single density foam material. As shown in  FIG. 2 , the prior art bat  26  is provided with an outer surface  30  and would also include a barrel section  28 , an end cap  36 , a tapered portion  34 , a handle  38  and an end knob  40 . The entire barrel portion of the bat  28  and possibly a small portion of the tapered section  34  abutting the barrel  28  would be filled with a single density foam material  32 . The foam would have a density and hardness correlated with the thickness of the bat wall in the hitting area. 
       FIGS. 3 and 4  illustrate a first embodiment of the present invention. These figures show a non-wood bat  42  including a barrel section  44  provided with an outer surface  46 , an end cap  50 , a handle  52  and a tapered section  48  extending between the barrel  44  and the handle  52 . Similar to prior art bats, an end knob  54  would be provided at the end of the handle section  52 . The entire interior section of the barrel  44  would be filled with two different types of foam material. The majority of the interior section of the barrel  44  would be filled with a relatively low compression inner foam material  58 . The tapered portion  48  and the handle portion  52  are not filled with the foam material and remain hollow for their entire length as shown by  60 . 
     This inner foam material  58  would be surrounded by a thin highly compressible outer foam layer  56 . The outer highly compressible foam layer  56  could be constructed from an open cell polyether or polyester foam having a compressive deflection of less than one psi to compress 25% of the volume of that outer foam layer  56 . The inner foam layer  58  is much less compressible than the outer foam layer  56 . This foam layer  58  can be constructed from an expanded polystyrene foam (EPS foam) or a closed cell polyethylene. The compressive deflection of the inner foam layer would be greater than 10 psi to compress 25% of the volume of this inner foam layer. The inner foam layer  58  would constitute approximately 85% to 95% of the inner volume of the barrel  44 , with the outer foam layer  56  constituting approximately 5% to 15% of inner volume of the barrel  44 . 
       FIG. 5  illustrates a second embodiment of the present invention which primarily illustrates the barrel portion  62  having an outer surface  64  of the bats illustrated with respect to  FIGS. 3 and 4 . Similar to  FIGS. 3 and 4 , the portion of the bat illustrated with respect to  FIG. 5  would include a relatively low compressibility foam layer  68  surrounded by a relatively high compressibility layer  66 . However, as illustrated with respect to  FIGS. 3 and 4 , the thickness of the outer foam layer  58  and the outer foam layer  56  is constant over the length of the barrel  44 . This is to be distinguished from the barrel  62  in which the thickness of the outer foam portion  66  and the inner foam portion  68  would gradually vary over the length of the barrel  62 . For example, the thickness of the outer foam layer  66  is smallest at approximately the middle portion of the bat  72 . The diameter of the outer foam layer  66  would gradually increase as it moves from the section  72  to section  70  as it approaches the end cap of the barrel as well as gradually increase as it approaches the tapered section of the bat at  74 . Since the inner foam layer  68  as well as the outer foam layer  66  fill the entire interior of volume of the barrel  62 , as the thickness of the outer foam layer  66  increases, the diameter of the inner foam layer  68  would decrease and vice versa. Similar to the embodiments illustrated with respect to  FIGS. 3 and 4 , the outer foam layer  66  is highly compressible whereas the inner foam layer  68  has a lower compression ratio. This would result in a higher damping and therefore less vibration created in section  72  with lower damping and therefore higher vibrations created in sections  70  and  74 . 
     The volume of both the inner and outer foam layers varies through the length of the barrel. For example, the volume of both of the foam layers would be approximately equal to one another close to the end cap as well as close to and end of the tapered portion. The ratio of the volume of the inner and outer layers would change as the inner and outer layer approach section  72  from both ends. For example, the volume of the inner layer  68  at section  72  would be approximately 90-95% of the entire inner volume of the barrel, and the volume of the outer layer would be approximately 5-10%. 
     The higher and lower density foam layers would be inserted into the interior of the barrel portion of the bat during the typical assembly process. 
     It is appreciated that various features of the present invention which are, for clarity, described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable subcombination. 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the claims as follows: