Patent Document

BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to baseball and softball bats. More particularly, the present invention relates to a bat having a vibration damping, flexible structure between the grip and the head of the bat.  
         [0002]     Baseball and softball are very popular sports in the United States, Mexico, Cuba, Japan and elsewhere. Due to the competitive nature of the sports, players are constantly seeking ways of improving their performance. An important aspect of baseball and softball is the ability to effectively hit the ball. Aluminum (metal) bats are allowed in baseball amateur play from Little League to College levels. Metal bats are also typically used in slow and fast pitch softball. Such bats are advantageous over wood bats in that they do not break and splinter like wood bats and thus can be repeatedly used with consequent cost savings. Metal bats also have a larger optimal hitting area or power zone (commonly referred to as the “sweet spot”) than wood bats. Furthermore, the ball comes off a metal bat faster than a wood bat resulting in longer hits.  
         [0003]     However, metal bats have certain disadvantages. Metal bats vibrate upon impact and may send painful vibrations into the hands and arms of the batter if the ball is not hit within the power zone of the bat. Metal bats, particularly aluminum bats, may also dent or otherwise deform due to forceful impacts with the ball. Metal bats also emit an undesirable high-pitched metallic sound, as opposed to the traditional sound heard when a wood bat contacts the ball.  
         [0004]     Various attempts have been made to overcome the problems associated with metal bats. Some attempts have been to coat or wrap the exterior of the metal bat with materials such as carbon reinforcing fibers to enhance batting performance. These externally wrapped bats have been found to be aesthetically unpleasant and lacking in significant improvement. Other attempts have been made to insert internal layers or compartments within the metal bat to improve performance. Such designs include utilizing multiple-layered graphite inserts to provide durability and flexibility to the bat, tubular coiled spring steel inserts to improve the spring-board effect when the ball contacts the bat, and pressurized air chambers within the bat. While providing benefits, these designs also have drawbacks. Some designs are very expensive to manufacture and are prone to structural failure. The composite sheaths break down over time and the bats are subject to premature longitudinal cracks in the barrel of the bat. In many of the newly designed metal bats, the reinforcement is focused around the optimal hitting area or center of the hitting area of the bat and do not run the length of the barrel of the bat.  
         [0005]     Accordingly, there is a need for a bat which enhances the performance of the bat and overcomes the disadvantages previously experienced with metal bats. The present invention fulfills these needs and provides other related advantages.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention resides in a vibration damping baseball bat that includes a barrel portion, a handle portion, and interconnects the barrel portion and the handle portion in an aligned and spaced-apart relation. The mechanism by which the barrel and handle portions are interconnected dampens vibrations created when a ball contacts the bat and provides limited pivotal movement of the barrel portion relative to the handle portion.  
         [0007]     The bat includes a first elastomeric washer disposed between the interconnecting mechanism and the barrel portion, and a second elastomeric washer disposed between the interconnecting mechanism and the handle portion.  
         [0008]     The interconnecting mechanism forms a tapered portion of the bat and includes an intermediate tapered section having first and second engaging members connected to, respectively, the barrel portion and the handle portion. In this manner, the first elastomeric washer is disposed between the tapered section and the barrel portion and the second elastomeric washer is disposed between the tapered section and the handle portion.  
         [0009]     The interconnecting mechanism includes a plug positioned within the barrel portion to receive the first engaging member. This barrel plug is sized and shaped to abuttingly engage the barrel portion when receiving the first engaging member. The barrel plug expands to wedge against the barrel portion as the plug receives the first engaging member. Threads within the barrel plug engage threads of the first engaging member, causing the plug to spread.  
         [0010]     Likewise, the interconnecting mechanism includes a plug positioned within the handle portion to receive the second engaging member. This handle plug is sized and shaped to abuttingly engage the handle portion when receiving the second engaging member. The handle plug expands to wedge against the handle portion as the plug receives the second engaging member. Threads within the handle plug engage threads of the second engaging member, causing the plug to spread.  
         [0011]     The tapered section is comprised of an elastomeric material to dampen vibrations created when a ball contacts the bat.  
         [0012]     The barrel and handle portions each include a tapered first end having an aperture. The barrel and handle plugs are each tapered and disposed within their respective portions of the bat near the aperture of that portion. Each plug abuttingly engages, respectively, the tapered first end of its respective portion when receiving the interconnecting mechanism.  
         [0013]     The interconnecting mechanism includes a mechanism for adjusting weight distribution of the bat. This adjustment mechanism includes a sleeve extending between the handle and barrel portions and a threaded rod received within the sleeve. A pair of threaded washers engage ends of the threaded rod that extend past the sleeve such that movement of at least one washer along the threaded rod adjusts weight distribution of the bat.  
         [0014]     Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The accompanying drawings illustrate the invention. In such drawings:  
         [0016]      FIG. 1  is a perspective view of a bat embodying the present invention;  
         [0017]      FIG. 2  is a cross-sectional elevation view of the bat of  FIG. 1  showing the handle, barrel and mechanism for interconnecting the barrel and handle;  
         [0018]      FIG. 3  is a perspective view of the interconnecting mechanism of  FIG. 2  with the bat shown in phantom; and  
         [0019]      FIG. 4  is an exploded perspective view of the handle, barrel and interconnecting mechanism;  
         [0020]      FIGS. 5-7  are cross-sectional elevation views showing the assembly of the bat by connecting the handle and the barrel using the interconnecting mechanism;  
         [0021]      FIG. 8  is a cross-sectional elevation view of another bat embodying the present invention that shows the handle, barrel and mechanism for interconnecting the barrel and handle;  
         [0022]      FIG. 9  is a perspective view of the interconnecting mechanism of  FIG. 8  with the bat shown in phantom;  
         [0023]      FIG. 10  is a partially exploded perspective view of the interconnecting mechanism of  FIG. 9 ;  
         [0024]      FIG. 11  is an exploded perspective view of the handle, barrel and interconnecting mechanism of the bat of  FIG. 8 ;  
         [0025]      FIGS. 12 and 13  are cross-sectional elevation views showing the assembly of the bat of  FIG. 8  by connecting the handle and the barrel using the interconnecting mechanism; and  
         [0026]      FIG. 14  is a flow chart illustrating the steps taken in manufacturing the bat of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]     As shown in  FIGS. 1-13  for purposes of illustration, the present invention is concerned with a bat  20  for use in baseball or softball, having an elongate hollow handle shell portion  22 , an elongate hollow barrel shell portion  24  and an intermediate cylindrically tapered section  26  interconnecting the handle portion  22  and the barrel portion  24 . A knob  28  may be welded or otherwise securely attached to the end of the handle portion  22 . The knob  28  may be made of various materials including, without limitation, aluminum, polyurethane, polycarbonate, a composite material or the like. Also, the handle portion  22  is typically wrapped with a grip  30  comprised of rubber, polyurethane, leather or the like, for comfort. The construction of the intermediate tapered section  26  dampens vibrations created when a ball contacts the bat  20  and provides limited pivotal movement of the barrel portion  24  relative to the handle portion  22 .  
         [0028]     The handle and barrel portions  22 ,  24  may be made of various materials including, without limitation, wood, a lightweight yet durable metal (e.g., aluminum, titanium, magnesium, or an alloy thereof, a composite material (e.g., fiberglass, carbon fibers, or a combination of glass and carbon fibers) or the like. Preferably, the handle and barrel portions  22 ,  24  are comprised of a 6000 or 7000 series aluminum alloy in which zinc is the major alloying element coupled with a smaller percentage of magnesium, resulting in a heat-treatable alloy of very high strength. The handle and barrel portions  22 ,  24  are finished to a mechanical strength of T6 Temper.  
         [0029]     The handle and barrel portions  22 ,  24  each include a tapered first end  32 ,  34  having an aperture  36 ,  38 . The intermediate tapered section  26  includes a central tapered connector  40  having generally cylindrical first and second engaging members  42 ,  44  and a central cylindrically tapered section  46  disposed therebetween. The tapered connector  40  is hollow and includes a central cavity  43  within the central section  46  and the engaging members  42 ,  44 . The diameters of the engaging members  42 ,  44  may be the same, or the diameter of one of the engaging members  42 ,  44  may be larger than the diameter of the other of the engaging members  44 ,  42 .  
         [0030]     A plug  48  positioned within the barrel portion  24  receives the first engaging member  42 . This barrel plug  48  is sized and shaped to abuttingly engage the barrel portion  24  when receiving the first engaging member  42 . The barrel plug  48  expands to wedge against an interior wall  50  of the barrel portion  24  as the plug  48  receives the first engaging member  42 . Likewise, a plug  52  positioned within the handle portion  22  receives the second engaging member  44 . This handle plug  52  is sized and shaped to abuttingly engage the handle portion  22  when receiving the second engaging member  44 . The handle plug  52  expands to wedge against an interior wall  54  of the handle portion  22  as the plug  52  receives the second engaging member  44 .  
         [0031]     The barrel and handle plugs  48 ,  52  are disposed within the interior of their respective portions  24 ,  22  of the bat  20  near the aperture  38 ,  36  of that portion  24 ,  22 . The end  32 ,  34  of each portion  22 ,  24  is curled or turned inwardly to create, respectively, an interior shoulder  56 ,  58  about the aperture  36 ,  38 . Each plug  52 ,  48  abuttingly engages, respectively, the shoulder  56 ,  58  and interior wall  54 ,  50  of the portion  22 ,  24  when the plug  52 ,  48  receives its respective engaging member  44 ,  42  of the connector  40 .  
         [0032]     A generally continuous taper is formed on the exterior surface of the intermediate tapered section  26  by the tapered end  34  of the barrel portion  24 , a first tapered cylindrical elastomeric washer  60  disposed between a shoulder  62  of the central section  46  and an exterior shoulder  64  of the tapered first end  34  of the barrel portion  24 , the central section  46  of the tapered connector  40 , a second tapered cylindrical elastomeric washer  66  disposed between another shoulder  68  of the central section  46  and an exterior shoulder  70  of the tapered first end  32  of the handle portion  22 , and the tapered end  32  of the handle portion  22 . The components of the intermediate tapered section  26  tightly fit together to isolate vibrations which insulates the handle portion  22  from vibrations generated in the barrel portion  24  when a ball strikes the barrel portion  24 . The length of the intermediate tapered section  26  will be varied based on the size and type of bat (e.g., adult baseball bat, youth baseball bat, softball bat or the like). A high strength bonding glue (not shown) may be applied to all joins to secure all the connections.  
         [0033]     The tapered connector  40  is comprised of a material to dampen vibrations created when a ball contacts the bat; isolating shock transmission from the barrel portion  24  to a hand of a batter gripping the handle portion  22  when a ball is in contact with the bat  20 . This material comes in various forms including, without limitation, an elastomeric material (e.g., solid rubber, high performance rubber foam, silicone or similar materials), polyurethane, polycarbonate, or a composite material (e.g., fiberglass, carbon fibers, or a combination of glass and carbon fibers). The plugs  48 ,  52  and washers  60 ,  66  may be made of the same materials as the connector  40 .  
         [0034]     An end  80  of the barrel portion  24  is typically open and directed inward for acceptance and retention of an end plug  82 . The end plug  82  is typically comprised of urethane, polyurethane, Zytel or the like. The end plug  82  has a circumferential groove  84  which accepts the inwardly directed annular lip  86  of the barrel portion  24 .  
         [0035]     As can be seen from  FIGS. 1-7 , in one embodiment of the present invention, each engaging member  42 ,  44  is generally cylindrical and includes exterior threads  72 ,  74  for engaging, respectively, the plugs  48 ,  52  of the barrel and handle portions  24 ,  22 .  
         [0036]     The barrel plug  48  is cylindrical tapered with a threaded bore  73  opening on an angled end  75 . The angle of the end  75  matches the angle of the interior shoulders  58  of the first end  34  of the barrel portion  24 ; the angle of the end  75  being between zero and forty-five degrees. The angle of the exterior shoulder  64  of the barrel portion  24  matches the angle of the exterior shoulder  62  of the central section  46 ; the angle of the exterior shoulder  62  being between zero and forty-five degrees. The washer  60  disposed between the shoulder  62  of the central section  46  and the exterior shoulder  64  of the first end  34  of the barrel portion  24  is compressed and bends to match this angle as the tapered connector  40  is connected to the barrel portion  24 .  
         [0037]     The handle plug  52  includes a cylindrical threaded bore  77  opening on an angled end  79 . The angle of the end  79  matches the angle of the interior shoulder  56  of the first end  32  of the handle portion  22 ; the angle of the end  79  being between zero and forty-five degrees. The angle of the exterior shoulder  70  of the handle portion  22  matches the angle of the exterior shoulder  68  of the central section  46 ; the angle of the exterior shoulder  68  being between zero and forty-five degrees. The washer  66  disposed between the shoulder  68  of the central section  46  and the exterior shoulder  70  of the tapered first end  32  of the handle portion  22  is compressed and bends to match this angle as the tapered connector  40  is connected to the handle portion  22 .  
         [0038]     Interior threads  76 ,  78  within bores  73 ,  77  of the plugs  48 ,  52  engage, respectively, the exterior threads  72 ,  74  of its engaging member  42 ,  44 . As the engaging members  42 ,  44  are threadedly received within the respective plug  48 ,  52 , the plug  48 ,  52  begins to spread until the plug  48 ,  52  abuts against the interior walls  50 ,  54  and shoulders  58 ,  56 . In the alternative, sides of the plugs  48 ,  52  may be comprised of a number of fingers (not shown) that spread to abut against the interior walls  50 ,  54  and shoulders  58 ,  56  as the engaging members  42 ,  44  are received within the respective plug  48 ,  52 .  
         [0039]     The bat  20  may be assembled in a number of ways. In one particular way, the barrel plug  48  is inserted through the open end  80  of the barrel portion  24  and positioned adjacent the aperture  38 . The diameter of the plug  48  is larger than the diameter of the aperture  38  so the plug  48  will not go through the aperture  38 . The handle plug  52  is inserted through the aperture  36  of the handle portion  22 . The diameter of the plug  52  is the same or smaller than the diameter of the aperture  36  but larger than the diameter of the handle portion  22  past the tapered end  32  so the plug  52  will not go through the handle portion  22  towards the knob  28 .  
         [0040]     The first washer  60  is positioned around the first engaging member  42  and disposed between the shoulder  62  of the central section  46  and the exterior shoulder  64  of the tapered first end  34  of the barrel portion  24 . The second washer  66  is positioned around the second engaging member  44  and disposed between the shoulder  68  of the central section  46  and the exterior shoulder  70  of the tapered first end  32  of the handle portion  22 . The engaging members  42 ,  44  are threadedly engaged to their respective plugs  48 ,  52  until the barrel and handle portions  24 ,  22  are tightly connected together by the tapered connector  40 . The end plug  82  is then secured to the end  80  of the barrel portion  24 .  
         [0041]     In another embodiment of the present invention, as seen in  FIGS. 8-13 , each engaging member  42 ,  44  is generally cylindrical and of constant diameter from where the engaging member  42 ,  44  is adjacent the central section  46  to about half its length when the engaging member  42 ,  44  tapers outwardly for the rest of its length.  
         [0042]     The barrel plug  48  is cylindrically tapered with a smooth-walled tapered bore  88  opening on an angled end  90 . The angle of the end  90  matches the angle of the interior shoulders  58  of the first end  34  of the barrel-portion  24 ; the angle of the end  90  being between zero and forty-five degrees. The angle of the exterior shoulder  64  of the barrel portion  24  matches the angle of the exterior shoulder  62  of the central section  46 ; the angle of the exterior shoulder  62  being between zero and forty-five degrees. The washer  60  disposed between the shoulder  62  of the central section  46  and the exterior shoulder  64  of the first end  34  of the barrel portion  24  is compressed and bends to match this angle as the tapered connector  40  is connected to the barrel portion  24 .  
         [0043]     The handle plug  52  is cylindrically tapered with a smooth-walled tapered bore  92  opening on an angled end  94 . The angle of the end  94  matches the angle of the interior shoulder  56  of the first end  32  of the handle portion  22 ; the angle of the end  94  being between zero and forty-five degrees. The angle of the exterior shoulder  70  of the handle portion  22  matches the angle of the exterior shoulder  68  of the central section  46 ; the angle of the exterior shoulder  68  being between zero and forty-five degrees. The washer  66  disposed between the shoulder  68  of the central section  46  and the exterior shoulder  70  of the tapered first end  32  of the handle portion  22  is compressed and bends to match this angle as the tapered connector  40  is connected to the handle portion  22 .  
         [0044]     Interior cylindrically tapered mounds  96 ,  98  within bores  88 ,  92  of the plugs  48 ,  52  engage, respectively, cylindrically tapered receptacles  100 ,  102  of its engaging member  42 ,  44 . When the engaging member  42 ,  44  is fully received within the bore  88 ,  92  of the respective plug  48 ,  52 , an end  104 ,  106  of the receptacle  100 ,  102  abuts against an end  108 ,  110  of mound  96 ,  98 . In the alternative, sides of the plugs  48 ,  52  may be comprised of a number of fingers (not shown) that spread to abut against the interior walls  50 ,  54  and shoulders  58 ,  56  as the engaging members  42 ,  44  are received within the respective plug  48 ,  52 .  
         [0045]     The tapered connector  40  and plugs  48 ,  52  are held together by press-fit engagement as well as by a mechanism for adjusting weight distribution  112  of the bat  20 . This adjustment mechanism  112  includes a sleeve  114  extending between the handle and barrel portions  22 ,  24  through a central bore  116  in the tapered connector  40  that has openings  118 ,  120  in the receptacles  100 ,  102  of the engaging members  42 ,  44 . Each plug  48 ,  52  also includes a central bore  122 ,  124  through which the sleeve  114  extends. Exterior ends  126 ,  128  of the sleeve  114  are threaded. Each plug  48 ,  52  includes a shallow hexagonal recess  130 ,  132  for receiving a threaded hexagonal washer  134 ,  136  that engages a respective threaded end  126 ,  128  of the sleeve  114 . The engagement of the washers  134 ,  136  and sleeve  114  help connect the tapered connector  40  and plugs  48 ,  52  together.  
         [0046]     A rod  138  with threaded ends  140 ,  142  is received within and extends past the ends  126 ,  128  of the sleeve  114 . Interior portions  150 ,  152  of the ends  126 ,  128  of the sleeve  114  are threaded to engage the threads of the threaded ends  140 ,  142  of the rod  138  and hold the rod  138  in position relative to the sleeve  114  until otherwise adjusted by a user. In the alternative, the entire exterior surface of the rod  138  may be threaded. In another alternative, the entire interior surface of the sleeve  114  may be threaded. A pair of threaded washers  144 ,  146  engage the threaded ends  140 ,  142  of the rod  138  that extend past the sleeve  114  such that movement of at least one washer  144 ,  146  along the threads of the rod  138  adjusts the weight distribution of the bat  20 . In a further alternative, the interior surface of the sleeve  114  may be smooth bored so as to allow the rod  138  to slidably move within the sleeve  114 , the rod  138  being held in place by the washers  144 ,  146  on the ends  140 ,  142  of the rod  138 . The washers  144 ,  146  may be the same weight or different weights. In this manner, centripetal acceleration would cause the rod  138  to slide within the sleeve  114  when the bat  20  is swung by a user, as well as causing mass of the bat  20  to shift between the handle and barrel portions  22 ,  24 .  
         [0047]     The bat  20  may be assembled in a number of ways. In one particular way, the barrel plug  48  is inserted through the open end  80  of the barrel portion  24  and positioned adjacent the aperture  38 . The diameter of the plug  48  is larger than the diameter of the aperture  38  so the plug  48  will not go through the aperture  38 . The washer  134  is threadedly engaged to the sleeve  114  and the sleeve  114  inserted into the plug bore  122  until the washer  134  is fully received within the recess  130 . The washer  144  is threadedly engaged to the rod  138  and the rod  138  inserted into the sleeve  114 . The first washer  60  is positioned around the first engaging member  42  and disposed between the shoulder  62  of the central section  46  and the exterior shoulder  64  of the tapered first end  34  of the barrel portion  24 .  
         [0048]     The sleeve  114  (and the rod  138  within and extending beyond the sleeve  114 ) pass through the central bore  116  and openings  118 ,  120  of the tapered connector  40  when the first engaging member  42  is received within the plug  48 .  
         [0049]     The tapered handle plug  52  is inserted one of the open ends of the handle portion  22  with the sides of the tapered plug  52  being compressed as necessary to position the plug  52  within the handle portion  22 . The taper of the plug  52 , once positioned, prevents the plug  52  from going through the handle portion  22  towards the knob  28  or through the aperture  36  of the handle end  32 . Once the plug  52  is in position, the second washer  66  is positioned around the second engaging member  44  and disposed between the shoulder  68  of the central section  46  and the exterior shoulder  70  of the tapered first end  32  of the handle portion  22 . The second engaging member  44  is then received within the plug  52  with the sleeve  114  (and the rod  138  within and extending beyond the sleeve  114 ) passing through the bore  124  of the plug  52 . The washers  136 ,  146  are then connected, respectively, to the sleeve  114  and rod  138  with the barrel and handle portions  24 ,  22  being connected together thereby. The end plug  82  is then secured to the end  80  of the barrel portion  24 .  
         [0050]     The interconnection of the handle portion  22  and the barrel portion  24  improves and amplifies the spring-board effect when the ball contacts the bat  20  by allowing the bat  20  to bend along the intermediate section  28  upon impact and then springing back to its original shape. The intermediate section  26  also reduces vibrations in that the components of the intermediate section  26  deflects, absorb and isolate vibrations traveling along the length of the barrel portion  24  towards the handle portion  22 , thus reducing the vibration created when a ball contacts the bat  20 . The width and depth of the intermediate section  26  can be varied to obtain the ultimate performance of the bat, depending on the design of the bat. The diameters and thicknesses of the handle portion  22 , barrel portion  24  and intermediate section  26  can be varied to alter the characteristics and performance of the bat  20 .  
         [0051]     The knob  28  includes a bore  148  that allows an Allen wrench to be inserted into the handle portion  22  to engage and adjust the position of the rod  138  within the sleeve  114 .  
         [0052]     An example of one particular method of manufacturing the bat  20  of the present invention will now be described. It is to be understood that the following method may be altered in some respects while still creating a bat  20  having the desired characteristics. Also, certain dimensions, materials, temperatures, etc. may be altered depending upon the size, weight and intended use of the resulting bat  20 . Accordingly, a softball bat having a length of 34 inches and weighting 28 ounces will be described by way of example in connection with the manufacturing method.  
         [0053]     Metal tubes, such as aluminum alloy tubes, are provided at predetermined lengths and weights prior to manufacturing. For purposes of the following example, aluminum alloy tubes are provided for the handle and barrel portions  22 ,  24 .  
         [0054]     With reference to  FIG. 14 , the metal tubes are first thermally treated ( 36 ). This is often referred to in the art as an annealing process. The thermal treatment softens the metal by removing the stress resulting from cold working. This process is to be repeated after a certain amount of cold work has been performed on the metal tubes. Before each cold forming process, the temperature of an anneal oven is set at 410° C. The aluminum tubes are heated in the oven at this temperature for approximately three hours. The oven temperature is then decreased by 20° C. per hour, after the three hour soak time, until the temperature of the tubes has reached 20° C. The aluminum tubes are then heated at a temperature of 230° C. for two hours, at which point the oven temperature is reset to 140° C. The tubes are removed from the oven when the temperature of the oven has reached 140° C.  
         [0055]     The tubes are then cleaned ( 38 ). During the annealing process, an oxidation scale develops on the surface of the aluminum tubes. An acid cleaning process is required to remove the oxidation scale. The tubes are soaked in a sulfuric acid solution for approximately thirty minutes to remove the oxidation scale each time the tubes are annealed.  
         [0056]     The tubes are then formed into handle and barrel portions  22 ,  24  of desired thickness, contour and length ( 40 ). This wall forming process is a cold working process. It is performed to obtain a wall of a desired thickness. Several cold forming passes may have to be performed depending upon several factors including metal type and the type of bat  20  desired. In the instant example, the tubes forming the aluminum handle and barrel portions  22 ,  24  are subject to the cold working process on the outside diameter and the wall thickness simultaneously to obtain a wall thickness of 0.055 inches with a tolerance of ±0.003 inches.  
         [0057]     The portions  22 ,  24  are then cleaned ( 42 ). A degreasing process is required to remove all lubricants and residue substances out of the aluminum portions  22 ,  24 . This is performed using an ultrasonic method with a detergent agent before and after the aluminum tube is annealed.  
         [0058]     The portions  22 ,  24  are then cut, trimmed and swaged to a desired length and contour ( 44 ). A thin end of each aluminum portion  22 ,  24  is trimmed to a predetermined length. It is important to have the thin ends of the aluminum portions  22 ,  24  squarely trimmed to avoid folding problems when the tubes are swaged by a rotary taper swager. The aluminum portions  22 ,  24  are swaged with a rotary swaging machine to obtain the desired contour shape and wall thickness. In the instant example, the required wall thickness after swaging is generally 0.055 inches with a tolerance of ±0.002 inches for the barrel portion  24 . The required wall thickness for the handle portion  22  is generally 0.085 inches with a tolerance of ±0.002 inches. The rotary swaging machine also contours the tapered ends  32 ,  34  of the handle  22  and barrel  24  portions.  
         [0059]     The tapered connector  40 , plugs  48 ,  52 , and washers  60 ,  66  may be formed using conventional methods which may vary according to whether a bat  20  of  FIGS. 1-7  or a bat  20  of  FIGS. 8-13  is desired. The tapered connector  40  is shaped to obtain a desired contoured shape.  
         [0060]     If necessary, after shaping, the handle and barrel portions  22 ,  24  are cut to the desired length. In the instant example, the total required length of the bat  20  is 34.5 inches and the weight is 17 ounces. From the end of the barrel portion  24  to an index is 19.5 inches, and from the index to the end of the handle portion  22  is 15 inches.  
         [0061]     The handle and barrel portions  22 ,  24  are then thermally treated, quenched and aged ( 46 ). It is commonly known in the art to expose metal or alloys to a heating and cooling treatment to obtain desired conditions, properties and an increase in strength. The handle and barrel portions  22 ,  24  are heat treated to obtain the highest tensile and yield strengths. The required temperature and time for the solution heat treatment is twenty-seven minutes at a temperature of 480° C. After the handle and barrel portions  22 ,  24  are heat treated, they are quenched immediately with either air or water. Quenching is a controlled rapid cooling of a metal from an elevated temperature by contact with a liquid, gas or solid. Precipitation from solid solution results in a change in properties of the alloy, usually occurring rapidly at elevated temperatures. The handle and barrel portions  22 ,  24  are aged in an oven for twelve hours at 135° C.  
         [0062]     The handle and barrel portions  22 ,  24  are then cleaned again ( 48 ). Due to the treatments in step  510 , the handle and barrel portions  22 ,  24  oxidize. This oxidation is removed by an anodizing process. The handle and barrel portions  22 ,  24  are anodized for five minutes. To eliminate all possible contaminations, the surface of the handle and barrel portions  22 ,  24  are then thoroughly cleaned with methyl ethyl ketone.  
         [0063]     At this point, the handle and barrel portions  22 ,  24  are assembled as outlined above, with respect to  FIGS. 1-7  and  FIGS. 8-13 .  
         [0064]     Thereafter, approximately a 0.50 inch portion of the open barreled end  80  is rolled inward at a 90° angle to accommodate the end plug  82 . If necessary, the protruded portion of the rolled portion is machined to achieve an opening of 1.25 inches in diameter for installing the end plug  82 .  
         [0065]     The bat  20  is then polished and decorated ( 52 ). Any appropriate methods of polishing and decoration, as are well known in the art, can be applied. In the preferred embodiment, the outer surfaces of the handle and barrel portions  22 ,  24  are exposed to sodium hydroxide to strip an anodize coating created during the manufacturing process as well as to prepare the outer surface for anodic coating process. Typically, the concentration of the sodium hydroxide is fifty grams per liter. The outer surface of the handle and barrel portions  22 ,  24  are mechanically polished to obtain a mirror finish. The external surface of the handle and barrel portions  22 ,  24  are then anodized. In the alternative, the external surface of the handle and barrel portions  22 ,  24  may be painted, chromed, powder-coated, or covered by some other method of decorative coating. The outer surface of the handle and barrel portions  22 ,  24  may be decorated with a graphic by using various methods such as silkscreening, heat transferring, or pad stamping.  
         [0066]     The bat  20  is completed by attaching the knob  28 , typically by welding a knob comprised of 5000 series or 6000 series aluminum alloy to an open end of the handle portion  22  opposite the tapered end  32 . The grip  30  and the end plug  82  are also installed to finish the bat  20  ( 54 ).  
         [0067]     In the alternative, the above described method of manufacturing the bat  20  may be varied. For example, physical characteristics of the bat  20 , such as the length, wall thickness or diameter may be increased or decreased.  
         [0068]     Although constructed from affordable medium to high strength, light weight, and commercially available materials, the bat  20  of the present invention offers the performance and advantages of expensive and high strength materials. The bat  20  provides improved dent resistance. The bat  20  also dampens the vibrations created when traditional metal bats hit the ball that would otherwise sting the hitter&#39;s hand when a bat contacts a ball. Premature longitudinal cracking of the barrel portion  24 , caused in traditional bats with thin wall thicknesses and high stress conditions, is avoided in the present invention.  
         [0069]     The above-described embodiments of the present invention are illustrative only and not limiting. It will thus be apparent to those skilled in the art that various changes and modifications may be made without departing from this invention in its broader aspects. Therefore, the appended claims encompass all such changes and modifications as falling within the true spirit and scope of this invention.

Technology Category: a