Patent Publication Number: US-6991551-B2

Title: Composite ball bat having a metal knob

Description:
BACKGROUND OF THE INVENTION 
     Baseball and softball bat manufacturers are continually attempting to develop low cost, lightweight ball bats that exhibit excellent durability and performance characteristics. Ball bats typically include a handle, a barrel, and a tapered section joining the handle to the barrel. A knob is typically attached to the free end of the handle, and a cap or other barrel closure is typically attached to the free end of the barrel. The outer shell of these bats is generally formed from aluminum or another suitable metal, and/or one or more composite materials. 
     Aluminum, or other metal, knobs are typically attached to metal ball bats via welding. Pins, screws, bolts, or other suitable attachment elements are alternatively used to attach the knobs to the bats. Aluminum knobs are desirable because they are durable, and are also relatively lightweight and inexpensive. Durability of a bat knob is important, as knobs are often subjected to stresses or forces when they are struck against a surface, such as when a batter slams the knob of a bat into the ground after striking out. Thus, aluminum knobs are generally preferred over less durable knobs in bat manufacturing. 
     Aluminum knobs cannot, however, be welded or otherwise readily attached to a composite, or other non-metal, bat handle. A common method for attaching a knob to a composite bat handle is to cast a polymer knob at the free end of the predominantly cylindrical bat handle. Structural integrity of the knob attachment is typically enhanced using one or more containment devices, such as pins and/or bolts. 
     The polymer knob is typically cast around the pins or bolts in order to improve the knob&#39;s structural performance. Unfortunately, the use of pins and bolts has a significant impact on the cost of manufacturing and the overall weight of the bat, and attaching a knob in this manner is a relatively lengthy process. Furthermore, polymer knobs are not nearly as durable as aluminum, or other metal, knobs. Thus, there is a need for a lightweight, low cost, durable knob that can be attached to a composite, or other non-metal, ball bat. 
     Attaching durable barrel caps to composite, or other non-metal, bats presents similar challenges. And barrel caps are more likely to be slammed into surfaces and struck by pitched balls, due to their location on the bat, than are bat knobs. Thus, there is also a need for a lightweight, low cost, durable barrel cap that can be attached to a composite, or other non-metal, ball bat. 
     SUMMARY OF THE INVENTION 
     The invention is directed to systems and methods for co-molding, or post-mold bonding, an aluminum, or other metal, tubular sleeve onto a predominantly cylindrical composite, or other non-metal, bat handle. An aluminum, or other metal, knob is attached to the metal tubular sleeve, via welding or another suitable attachment method. Similar methods may be used for attaching barrel end closures, e.g. barrel caps, to the end of the bat barrel. In these methods, a metal insert is co-molded or post-mold bonded onto the barrel of the bat. A metal barrel cap is then welded, or otherwise attached, to the metal insert to close the end of the bat. Alternatively, a cap retention device may be co-molded, or post-mold bonded, onto the barrel of the bat. A plastic, or other suitable material, cap is then attached to the cap retention device. 
     In a first aspect, a ball bat includes a metal sleeve co-molded onto a non-metal bat handle, such that the metal sleeve is integral with the bat handle. A metal knob is attached to the metal sleeve, preferably via a weld. One or more screws, or another suitable attachment device, may alternatively be used to attach the metal knob to the metal sleeve. 
     In another aspect, a metal insert is co-molded onto the bat barrel. A metal cap is attached to the metal insert, preferably via a weld or another suitable attachment device. 
     In another aspect, a cap retention device is co-molded onto the bat barrel. A plastic cap, or other suitable cap, is attached to the cap retention device. 
     In another aspect, the metal sleeve is positioned at least 0.25 inches from a terminal end of the bat handle. 
     In another aspect, the metal sleeve has a length of 0.25 to 2.0 inches. 
     In another aspect, the metal sleeve has a thickness of 0.02 to 0.07 inches. 
     In another aspect, a ball bat includes a metal sleeve bonded onto a non-metal handle, and a metal knob attached to the metal sleeve. 
     In another aspect, a method of constructing a ball bat includes the steps of arranging non-metal layers of the ball bat onto a bat-shaped mold, placing a metal sleeve onto the handle section of the ball bat, and co-curing the layers of the ball bat and the metal sleeve to integrate the metal sleeve with the bat handle. A metal knob is then attached to the metal sleeve, preferably via welding. Screwing, or another suitable attachment method, may alternatively be used to attach the metal knob to the metal sleeve. 
     In another aspect, a method of constructing a ball bat includes the step of placing a metal insert onto the barrel section before the co-curing step, such that the metal insert is co-cured with the layers of the ball bat during the co-curing step. 
     In another aspect, a method of constructing a ball bat includes the step of attaching a metal cap to the metal insert after the co-curing step. 
     In another aspect, a method of constructing a ball bat includes the step of placing a cap retention device onto the barrel before the co-curing step, such that the cap retention device is co-cured with the layers of the ball bat during the co-curing step. 
     In another aspect, a method of constructing a ball bat includes the step of attaching a plastic cap to the cap retention device. 
     In another aspect, a method of constructing a ball bat includes the steps of arranging non-metal layers of the ball bat onto a bat-shaped mold, curing the layers of the ball bat, and bonding a metal sleeve onto the handle section. A metal knob is then attached to the metal sleeve, preferably via welding. Screwing, or another suitable attachment method, may alternatively be used to attach the metal knob to the metal sleeve. 
     Further embodiments, including modifications, variations, and enhancements of the invention, will become apparent. The invention resides as well in subcombinations of the features shown and described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, wherein the same reference number indicates the same element throughout the several views: 
         FIG. 1  is a perspective view of a ball bat. 
         FIG. 2  is a side view of a non-metal bat handle with a metal sleeve positioned around the handle. 
         FIG. 3  is a partial side-sectional view of the bat handle illustrated in  FIG. 2  with a metal knob attached to the metal sleeve. 
         FIG. 4  is a partial side-sectional view of a non-metal bat barrel including a metal insert, with a metal barrel cap attached to the metal insert. 
         FIG. 5  is a partial side-sectional view of a non-metal bat barrel including a cap retention device, with a barrel cap attached to the cap retention device. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Turning now in detail to the drawings, as illustrated in  FIGS. 1–3 , a baseball or softball bat  10 , hereinafter collectively referred to as a “ball bat” or “bat,” includes a handle  12 , a barrel  14 , and a tapered section  16  joining the handle  12  to the barrel  14 . A knob  18  or similar structure is attached to the free end  17  of the handle  12 . The knob  18  is preferably aluminum, or another suitable metal. The barrel  14  is preferably closed off by a suitable cap  20  or plug. The cap may be aluminum, or another suitable metal, or it may be plastic or another suitable material. The manner in which the knob  18  and cap  20  are attached to the bat  10  is described in detail below. The interior of the ball bat  10  is preferably hollow, which allows the ball bat  10  to be relatively lightweight so that ball players may generate substantial bat speed when swinging the bat  10 . 
     The ball bat  10  preferably has an overall length of 20 to 40 inches, more preferably 26 to 34 inches. The overall barrel diameter is preferably 2.0 to 3.0 inches, more preferably 2.25 to 2.75 inches. Typical bats have diameters of 2.25, 2.69, or 2.75 inches. Bats having various combinations of these overall lengths and barrel diameters, as well as other sizes, are contemplated herein. The specific preferred combination of bat dimensions is generally dictated by the user of the bat  10 , and may vary greatly between users. 
     The barrel  14  is preferably made up of one or more substantially cylindrical layers. The actual shape of each barrel layer may vary according to the desired shape of the overall barrel structure. The barrel  14  may include a single wall, or two or more walls. U.S. Pat. No. 5,364,095, which is herein incorporated by reference, describes a variety of bats having multi-walled barrel constructions. 
     The barrel, handle, and tapered section preferably each include one or more composite plies, or one or more layers of another suitable non-metallic material. The composite materials are preferably fiber-reinforced, and may include glass, graphite, boron, carbon, aramid, ceramic, kevlar, and/or any other suitable reinforcement material. 
     A tubular metal sleeve  22  or cylinder is preferably co-molded onto the outer diameter of the composite (or other non-metal) bat handle  12 , as described below, such that the metal sleeve  22  is integral with the bat handle  12 . The metal sleeve  22  is preferably made of aluminum and/or another suitable metal. 
     The metal knob  18  is attached to the metal sleeve  22 , preferably via a weld  24 , one or more screws or pins, or another suitable attachment device. Welding is the preferred attachment method, as welding is generally faster and cheaper than the other attachment methods. For example, welding a metal knob  18  onto a metal sleeve  22  typically takes approximately five seconds, whereas drilling holes into the knob and handle, to facilitate attachment of the knob via screws or pins, typically takes several minutes. Additionally, the cost of the screws or pins is saved when the knob  18  is welded onto the metal sleeve  22 . 
     In an alternative embodiment, the metal sleeve  22  is bonded onto the handle  12  after the molding or curing process is performed on the bat  10 . The metal sleeve  22  may be bonded to the handle  12  with adhesive, epoxy, or another suitable bonding agent. The metal knob  18  is then attached to the metal sleeve  22  via welding or another suitable attachment method, as described above. When this post-mold bonding method is used, a bond interface forms between the metal sleeve  22  and the handle  12 , which results in the attachment between the metal sleeve  22  and the handle  12  not being as strong as the integration provided by the co-molded embodiment described above. Thus, the co-molding method is preferred over the post-mold bonding method, because the metal sleeve  22  becomes integrated with or encapsulated by the composite (or other non-metal) handle  12 , which provides a stronger integration than the post-mold bonding method. 
     The metal sleeve  22  is preferably positioned at least 0.25 inches from the terminal end  17  of the bat handle  12 , to provide sufficient shear strength against pullout loading, i.e., to prevent the metal sleeve  22  from shearing off of the handle  12  under loading conditions. The metal sleeve  22  may alternatively be located closer to the terminal end  17  of the handle  12 , since the co-molding and post-mold bonding processes both provide a secure integration or attachment. From a design standpoint, however, it is preferable to locate the metal sleeve  22  at least 0.25 inches from the terminal end  17  of the bat handle  12 , since the knob  18  can be attached to the metal sleeve  22  at a position that is distal from the terminal end  17  of the ball bat  10 , as shown in  FIG. 3 , and the metal sleeve  22  therefore does not need to be located at the extreme end of the handle  12 . 
     The metal sleeve  22  or cylinder preferably has a length of 0.25 to 12.0 inches, more preferably 0.25 to 2.0 inches, and a thickness of 0.02 to 0.07 inches, more preferably 0.05 to 0.07 inches. The diameter of the metal sleeve is generally determined by the outer diameter of the bat handle  12 . For example, on a softball bat  10  having a 0.810 inch diameter handle  12 , in the co-molding embodiment, the metal sleeve  22  preferably also has an outer diameter of approximately 0.810 inches, so that the outer surface of the metal sleeve  22  is substantially flush with the outer surface of the bat handle  12 . 
     In the post-mold bonding embodiment, the metal sleeve  22  may have the same outer diameter as the bat handle  12  (in which case the actual handle portion beneath the metal sleeve  22  would have a slightly smaller diameter), or it may have a slightly larger diameter. For example, on a bat with a 0.810 inch diameter handle  12 , the metal sleeve  22  may have an outer diameter of approximately 0.865 to 0.880 inches, and an inner diameter slightly greater than the 0.810 inch diameter of the handle  12 , so that the metal sleeve  22  can be slipped onto the handle  12  after the molding or curing process. The metal sleeve  22  may be sized to fit on any size bat handle  12 . 
     As illustrated in  FIG. 4 , an aluminum, or other metal, barrel cap  20  may be attached to a composite, or other non-metal, bat barrel  14  in a manner similar to that described above for attaching a metal knob  18  to a non-metal bat handle  12 . In this embodiment, a metal insert  30  is preferably co-molded onto or into the composite (or other non-metal) bat barrel  14 , as described below, such that the metal insert  30  is integral with the bat barrel  14 . The metal insert  30  is preferably made of aluminum and/or another suitable metal. 
     A metal barrel cap  20  is attached to the metal insert  30 , preferably via a weld  32 , one or more screws or pins, or another suitable attachment device. Welding, which is generally faster and cheaper than the other attachment methods, is the preferred attachment method, as described above. The metal insert  30  preferably includes a recessed portion  34  beginning at the barrel cap  20  attachment or weld point, so that the outer surface of the barrel cap  20  may be flush with the outer surface of the bat barrel  14  after attachment. Other barrel cap and metal insert shapes may alternatively be used. 
     In an alternative embodiment, the metal insert  30  is bonded onto the barrel  14 , with adhesive, epoxy, or another suitable bonding agent, after the molding or curing process is performed on the bat  10 . The barrel cap  20  is then attached to the metal insert  30  as described above. In this embodiment, a bond interface is formed between the metal insert  30  and the barrel  14 , which results in the attachment between the metal insert  30  and the barrel  14  not being as strong as the integration provided by the co-molded embodiment described above. Thus, the co-molding method is preferred over the post-mold bonding method, because the metal insert  30  becomes integrated with or encapsulated by the composite (or other non-metal) barrel  14 , which provides a stronger integration than the post-mold bonding attachment method. 
     In another alternative embodiment, a cap retention device  40  is co-molded onto or into the composite (or other non-metal) bat barrel  14 , as described below, such that the cap retention device  40  is integral and flush with the bat barrel  14 . The cap retention device  40  may alternatively be bonded onto the barrel  14 , with adhesive, epoxy, or another suitable bonding agent, after the molding or curing process is performed on the bat  10 . The cap retention device  40  is preferably made of aluminum and/or another suitable metal, or another durable material. The cap retention device  40  may be a forged end of the barrel  14 , a snap ring, or another suitable retention device. A plastic, or other suitable material, barrel cap  20 ′ is attached to the cap retention device  40 . In the embodiment illustrated in  FIG. 5 , a flexible arm  21  of the barrel cap  20 ′ slides over and snaps behind a radially inwardly extending portion  42  of the cap retention device  40 . Other suitable means or methods of attachment may alternatively or additionally be used. 
     The metal insert  30  or cap retention device  40  preferably has a length of 0.25 to 4.0 inches, more preferably 0.25 to 1.0 inch, and a thickness of 0.02 to 0.07 inches, more preferably 0.05 to 0.07 inches. The outer diameter of the metal insert  30  or cap retention device  40  is preferably the same as the outer diameter of the bat barrel  14 , such that the outer surface of the metal insert  30  or cap retention device  40  is flush with the outer surface of the bat barrel  14 . The metal insert  30  or cap retention device  40  may be sized to fit any size bat barrel  14 . 
     One or more of the above described features may be used alone or in combination with one another. For example, a metal knob  18  may be attached to a metal sleeve  22  on the bat handle  12 , and a metal cap  20  or a plastic cap  20 ′ may be attached to a metal insert  30  or a cap retention device  40 , respectively, on the bat barrel  14 . Alternatively, only one of a metal knob  18  and a metal barrel cap  20  or a plastic barrel cap  20 ′ may be attached to the composite, or other non-metal, ball bat  10 . By using one or more of these features, bat durability is increased, while manufacturing costs and/or bat weight are reduced. 
     The ball bat  10  is generally constructed by rolling or arranging the various layers of the bat  10  onto a mandrel or similar bat-shaped mold, as described in U.S. patent application Ser. No. 10/336,130, filed Jan. 3, 2003, which is herein incorporated by reference. In the co-molding embodiments described above, once the composite, or other non-metal, layers of the ball bat are arranged onto the bat-shaped mold, a metal sleeve  22  is slipped or otherwise placed onto the handle section  12  of the ball bat  10 , or the layers of the handle section are squeezed through the metal sleeve  22 . Additionally or alternatively, a metal insert  30  or cap retention device  40  may be positioned or arranged onto or into the barrel section  14 , as described above. 
     Internal pressure and/or heat are then applied to the ball bat  10  to co-cure or co-mold the layers of the ball bat  10 , the metal sleeve  22 , and/or the metal insert  30  or cap retention device  40  together. This co-curing process allows the composite, or other non-metal, material to encapsulate the metal sleeve  22  and/or the metal insert  30  or cap retention device  40 , making them integral parts of the bat handle  12  and/or the bat barrel  14 . Once the co-curing process is complete, and the bat  10  has sufficiently cooled, a metal knob  18  is welded or otherwise attached (e.g., by screwing or pinning) to the metal sleeve  22 , as described above. If a metal insert  30  is co-cured with the bat barrel  14 , a metal barrel cap  20  is subsequently welded or otherwise attached to the metal insert  30 , as described above. If a cap retention device  40  is co-cured with the bat barrel  14 , a plastic, or other suitable material, cap  20 ′ is subsequently snapped onto or otherwise attached to the cap retention device  40 , as described above. 
     In an alternative method of constructing the ball bat  10 , the layers of the ball bat  10  are cured before the metal sleeve  22  and/or the metal insert  30  or cap retention device  40  are placed, slipped, or arranged on the ball bat  10 . After the ball bat  10  has been cured and has sufficiently cooled, the metal sleeve  22  and/or the metal insert  30  or cap retention device  40  are positioned on the bat handle  12  or bat barrel  14 , respectively, and are then bonded thereto with an adhesive, epoxy, or other suitable bonding agent. The metal knob  18  is then attached to the metal sleeve  22 , and/or the metal cap  20  or plastic cap  20 ′ is attached to the metal insert  30  or cap retention device  40 , as described above. The co-curing methods are preferred over the post-mold bonding methods, however, because the metal sleeve  22  and/or the metal insert  30  or cap retention device  40  become integrated with or encapsulated by the composite (or other non-metal) handle  12  or barrel  14  during the co-curing methods, which provides a stronger integration than the post-mold bonding attachment methods. 
     The ball bat  10  described herein provides a more durable knob  18  and/or barrel cap  20  or  20 ′ than that which is typically used on a composite, or other non-metal, ball bat. Additionally, the manufacturing costs and/or manufacturing time associated with the ball bat  10  are reduced, since the metal knob  18  and/or the metal cap  20  or plastic cap  20 ′ may be attached via welding (or snapping, in the case of the plastic cap  20 ′), as opposed to using pins or screws, which is typically costly and time-consuming. Furthermore, the undesirable weight provided by pins or screws is avoided when the metal knob  18  and/or the metal cap  20  or plastic cap  20 ′ are attached via welding or snapping. 
     Thus, while several embodiments have been shown and described, various changes and substitutions may of course be made, without departing from the spirit and scope of the invention. The invention, therefore, should not be limited, except by the following claims and their equivalents.