Abstract:
Deadblow hammers capable of minimizing or eliminating recoils when the hammers impact their targets are discussed. These hammers have easy access anti-recoil chambers, at least one insert element placed inside the anti-recoil chamber, and improved openings for inserting the insert element. The insert element or elements function to negate the effects of the hammer recoils. Golf clubs with anti-recoil chamber and insert elements are also discussed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a continuation-in-part application of Ser. No. 11/595,534, filed Nov. 9, 2006, entitled Deadblow Hammer, which is a continuation application of Ser. No. 11/106,226, filed Apr. 13, 2005, entitled Deadblow Hammer, now U.S. Pat. No. 7,134,363, which is a continuation of Ser. No. 10/246,867, filed Sep. 17, 2002, entitled Deadblow Hammer, now U.S. Pat. No. 6,904,829, the contents of each of which are expressly incorporated herein by reference. 
     
    
     FIELD OF ART  
       [0002]     Deadblow hammers capable of minimizing or eliminating recoils when the hammers impact their targets are discussed herein. These hammers incorporate one or more insert elements, which function to negate the effects of the hammer recoils.  
       BACKGROUND  
       [0003]     It is a well-known principle that every action has an equal and opposite reaction (Newton&#39;s Third Law). Thus, for a hammer, when the impact surface of the hammer head impacts a target, the hammer is jolted backwards due to the reaction caused by the hammer head striking its target. This opposite reaction is commonly referred to as hammer recoil.  
         [0004]     For minimizing or eliminating hammer recoils, which cause vibrations and injuries to the user, numerous hammers were invented. Broadly speaking, these hammers utilize some form of inserts placed in a hollow chamber within the hammer head, or within a separate hollow body having a hollow chamber attached to the hammer head. The inserts are configured to move from a rear surface of the hollow chamber to a front surface of the hollow chamber. Accordingly, when the hammer moves in a first direction to impact its target, the inserts are pushed by the rear surface of the hollow chamber to move in the same first direction.  
         [0005]     As the impact surface of the hammer head impacts a target and starts its recoil in a second direction, the inserts still move in the first direction within the hollow chamber and impact the front surface of the hollow chamber, in the first direction. The inserts impacting against the front surface of the hollow chamber thus cancel the recoil in total or substantially. The amount of cancellation depends, in part, on the weight percentage of the inserts compared to the weight of the hammer head. Without being restricted to any particular theory, the deadblow impact or feel to the user also depends on the distance the insert travels before it impacts the front surface, which will influence how far the hammer recoils before the insert impacts the front surface to cancel out the effect.  
         [0006]     U.S. Pat. No. 6,234,048 to Carmien discloses a non-recoil hammer, with a hammer head that has an open socket for receiving a separate hollow canister. The hollow canister connects to a tool handle and contains a relatively high mass moveable filler material in a hollow chamber, such as steel shot pellets. The hollow canister is received within the open socket to form a completed hammer. Due to the two-piece design, the hammer is more complicated and costly to manufacture.  
         [0007]     U.S. Pat. No. 5,916,338 to Bergkvist et al. discloses a hammer having a hammer head with an impact element and a cavity at least partially filled with particulate material, such as steel shot, so as to dampen the recoil of the hammer. The impact element is forged with the head as a single piece or may be formed as a separate part that is connected to the head by welding. However, since the cavity extends the full length of the hammer head, the handle cannot attach to the hammer head by passing through a central portion of the hammer head, but is attached via a partial through hole at the central portion of the hammer head. This makes the handle more susceptible to slippage or separation from the hammer head. Furthermore, because of the cavity, a conventional handle with a split end for wedging the handle with a wedge is not useable with the disclosed hammer head.  
         [0008]     U.S. Pat. No. 4,039,012 to Cook discloses a non-rebound hammer having a hammer head portion with forwardly and rearwardly facing metallic impact surfaces. The head portion contains a hollow cylindrical core for receiving a quantity of pellets, such as small lead shots. The hammer head also contains a core hole for receiving a handle rod. The handle rod and the hammer head are then co-molded with an encasement. Due to the co-molded configuration, the entire hammer must be discarded when damage is done to the handle.  
         [0009]     U.S. Pat. No. 2,604,914 to Kahlen discloses a hammer head having a rebound-preventing means. The hammer head has a body with a striking head at each end of the body. Each striking head is formed integrally with the body, or alternatively it may be secured to the body as a separate piece. A chamber is formed in the body immediately behind the striking heads. The chamber contains irregularly shaped particles  26 , as shown in  FIG. 3  of the &#39;914 patent. The particles almost completely fill the chamber, with the total weight of the particles dependent on the recoil quality of the striking head, the size of the hammer, and the weight of the head. Due to the lengthwise chamber, a ferrule is used to connect a handle to the body. This makes the body unnecessarily bulky.  
         [0010]     There is therefore a need for a non-recoil hammer or deadblow hammer that minimizes or negates the effects of hammer recoils and that do so without the shortcomings of prior art deadblow hammers. Additionally, there is also a need for a method of making the desired deadblow hammer.  
       SUMMARY  
       [0011]     The present invention specifically addresses and alleviates the above-mentioned deficiencies associated with the prior art anti-recoil hammers. More particularly, the present invention comprises a deadblow hammer comprising a hammer head having a body, an anti-recoil chamber for receiving a plurality of insert elements located within a section of the body, and an open socket defined by a handle chamber which passes through the body for receiving a handle. The anti-recoil chamber comprises a first opening that is in communication with the open socket and that provides a first passage into the anti-recoil chamber, the first opening allowing the plurality of insert elements to be placed into the anti-recoil chamber by way of the open socket; and wherein insertion of the handle into the handle chamber seals off the first opening and occupies the open socket. Together, these features define a deadblow hammer that is more economical to make and that has an anti-recoil chamber that is easy to access.  
         [0012]     The present invention also involves a deadblow hammer comprising a hammer head having a body, two anti-recoil chambers, each having a plurality of insert elements situated therein and an impact surface attached adjacent thereto, and an open socket defined by a handle chamber that passes through the body for receiving a handle. This hammer is commonly known in the art as a sledge hammer.  
         [0013]     The two anti-recoil chambers in the sledge hammer each comprise a first opening that is in communication with the open socket and that provides a first passage into the anti-recoil chamber from the open socket; the first opening allows the plurality of insert elements to be placed into the anti-recoil chamber by way of the open socket; and wherein an insertion of the handle into the handle chamber seals off the first opening of each of the anti-recoil chamber and causes the open socket to be occupied.  
         [0014]     The present invention also involves a golf club head comprising a club face, a hosel for attaching the club head to a shaft, and a hollow chamber disposed within the club head; and wherein the hollow chamber includes insert elements for negating and dampening recoils when the golf club head impacts a solid surface.  
         [0015]     In another embodiment, a deadblow hammer comprises a hammer head comprising a body section having an interior surface defining an anti-recoil chamber having an internal cross-sectional dimension, the hammer head further comprising a handle chamber, an impact surface, a front wall disposed opposite the impact surface, and at least one of a back wall opposite the front wall and an opening in communication with the handle chamber. The hammer also includes a handle attached to the handle chamber. An insert element is disposed within the anti-recoil chamber and contacts the interior surface of the body section. The insert element has a width that is about 50 percent to about 95 percent of the internal cross-sectional dimension of the anti-recoil chamber and is movable within the anti-recoil chamber and contacts both the front wall and at least one of the back wall and the handle.  
         [0016]     In yet another embodiment, a deadblow hammer comprises a hammer head comprising an impact surface and a body section having an interior surface defining an anti-recoil chamber having an internal width, the interior surface having an opening. A handle is attached to the hammer head. An insert element is placed in the anti-recoil chamber by way of the opening, the insert element having a width that is greater than half the internal width of the anti-recoil chamber. The insert element is movable within the anti-recoil chamber and contacts the interior surface of the body section. The opening is adapted to be closed after placement of the insert element. The anti-recoil chamber is defined by a front wall disposed opposite the impact surface, the interior surface of the body section, and at least one of a portion of the handle and a back wall opposite the front wall. The insert element is adapted to contact at least one of the portion of the handle and the back wall when the hammer is swung forward.  
         [0017]     In still another embodiment, a deadblow hammer comprises a hammer head comprising an anti-recoil chamber having an internal cross-sectional dimension, the hammer head further comprising a handle chamber, an impact surface, a front wall disposed opposite the impact surface, and at least one of a back wall opposing the front wall and an opening in communication with the handle chamber. The hammer also includes a handle attached to the handle chamber. An insert element is disposed within the anti-recoil chamber. The insert element has a width that is about 50 percent to about 95 percent of the internal cross-sectional dimension of the anti-recoil chamber and is rotatable and translatable within the anti-recoil chamber. The insert element contacts both the front wall and at least one of the back wall and the handle. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     These and other features, aspects and advantages of the present invention will be more fully understood when considered with respect to the following detailed description, appended claims and accompanying drawings, wherein:  
         [0019]      FIG. 1  is a semi-schematic perspective view of an exemplary deadblow hammer provided in accordance with practice of the present invention;  
         [0020]      FIG. 2  is a semi-schematic cross-sectional side view of the deadblow hammer of  FIG. 1 ;  
         [0021]      FIG. 2A  is a semi-schematic cross-sectional view of the deadblow hammer of  FIG. 1  with a v-groove;  
         [0022]      FIG. 3  is a semi-schematic cross-sectional side view of the hammer of  FIG. 2  with an alternative anti-recoil chamber;  
         [0023]      FIG. 4  is a semi-schematic cross-sectional side view of the hammer of  FIG. 2  with another alternative anti-recoil chamber;  
         [0024]      FIG. 5  is a semi-schematic cross-sectional side view of the hammer of  FIG. 2  with yet another alternative anti-recoil chamber;  
         [0025]      FIG. 5   a  is a semi-schematic cross-sectional side view of the hammer of  FIG. 2  with side openings;  
         [0026]      FIG. 6  is a semi-schematic top plan view of the hammer head of  FIG. 1 ;  
         [0027]      FIG. 7  is a semi-schematic end view of the hammer head of  FIG. 2  taken at line A-A;  
         [0028]      FIG. 8  is a semi-schematic end view of the impact plate provided in accordance with practice of the present invention;  
         [0029]      FIG. 9  is a semi-schematic cross-sectional view of the impact plate of  FIG. 8  taken at line B-B;  
         [0030]      FIG. 10  is a semi-schematic cross-sectional view of an alternative hammer head provided in accordance with practice of the present invention;  
         [0031]      FIG. 11  is a manufacturing flow diagram provided in accordance with practice of the present invention;  
         [0032]      FIG. 12  is a metal golf club having an anti-recoil chamber provided in accordance with practice of the present invention;  
         [0033]      FIG. 13  is a metal wood golf club having an anti-recoil chamber made from a tube provided in accordance with practice of the present invention;  
         [0034]      FIG. 14   a  is a semi-schematic cross-sectional side view of an exemplary deadblow hammer provided in accordance with practice of the present invention;  
         [0035]      FIG. 14   b  is a semi-schematic cross-sectional side view of another embodiment of the deadblow hammer of  FIG. 14   a;    
         [0036]      FIG. 15   a  is a semi-schematic cross-sectional side view of an exemplary hammer head provided in accordance with practice of the present invention;  
         [0037]      FIG. 15   b  is a semi-schematic side view of another embodiment of the hammer head of  FIG. 15   a;    
         [0038]      FIG. 16  is a semi-schematic cross-sectional view of an alternative hammer head provided in accordance with practice of the present invention;  
         [0039]      FIG. 17  is a semi-schematic cross-sectional side view of an exemplary deadblow hammer provided in accordance with practice of the present invention;  
         [0040]      FIG. 18   a  is a semi-schematic cross-sectional side view of an exemplary hammer head provided in accordance with practice of the present invention;  
         [0041]      FIG. 18   b  is a semi-schematic cross-sectional side view of another embodiment of the hammer head of  FIG. 18   a ; and  
         [0042]      FIG. 19  is a semi-schematic cross-sectional side view of an exemplary hammer head provided in accordance with practice of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0043]     The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiments of the deadblow hammer in accordance with the present invention and is not intended to represent the only forms in which the present invention may be constructed or utilized. The description sets forth the features and the steps for constructing and using the deadblow hammer of the present invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. Also, as denoted elsewhere herein, like element numbers are intended to indicate like or similar elements or features.  
         [0044]     Referring now to  FIG. 1 , there is shown a deadblow hammer (“hammer”) provided in accordance with practice of the present invention, which is generally designated  10 . The hammer  10  comprises a hammer head  12 , which includes a body  14 , an impact section  16 , an impact plate  17  having an impact surface  18  and a claw  20 . The hammer  10  further comprises a handle  22 , which includes an attachment portion  24  for attaching to the open socket  26  of the hammer head  12  and a handle portion  28  for facilitating gripping of the hammer  10 . The handle  22  is shown with an optional handle grip  30 , which may be made from a rubber material and slidably inserted over the handle portion  28  of the handle  22 .  
         [0045]     The hammer head  10  is preferably cast from a steel material but alternatively may be forged from a steel block. The handle  22  may be any number of conventional handles, including handles made from wood, plastic, and fiberglass.  
         [0046]     Referring now to  FIG. 2 , there is shown a semi-schematic cross-sectional view of the hammer  10  of  FIG. 1 . As shown, the hammer head  12  comprises a hollow chamber  32 , which is also referred to herein as an anti-recoil chamber. The hollow chamber  32  comprises an enlarged chamber section  34 , a relatively smaller tail chamber section  36 , and a tapered transitional section  38 . The tapered transitional section  38  may include a straight taper, as shown, or a curved taper. The hollow chamber  32  further includes a first opening  40  that is just proximal of the tail chamber section  36 . The first opening  40  opens into the open socket  26  and is in communication with the open socket. However, once the handle  22  is inserted into the open socket  26 , the communication is severed and the attachment portion  24  of the handle occupies the open socket ( FIG. 2 ). Although the open socket  26  is shown with a straight wall, it is understood that a tapered wall may be incorporated without deviating from the scope of the present invention.  
         [0047]     A separate impact plate  17  is shown attached to the body  14  of the hammer head  12  and covers the hollow chamber&#39;s second opening  42 . The second opening  42  is shown larger than the first opening  40 . However, the arrangement is merely a designer&#39;s choice as the relative dimensions between the first opening  40  and the second opening  42  may be reversed. The impact plate  17  may be attached to the body  14  by conventional welding methods, by threads, or by inertia welding. In inertia welding, the body  14  is held in a lath and spins at relatively high speed. The lath used for inertia welding can be a vertical standing lath or a horizontal lath. The impact plate  17 , which is not spinning, is then pushed against the spinning end surface  44  of the second opening  42 . The friction generated by the contact causes the impact plate  17  and the end surface  44  to partially melt, which results in their fusion. As a by-product of their impact, a protruding section  46  is formed on the impact plate  17 , which protrudes into the hollow chamber  32 . Alternatively, the impact plate  17  can be rotated in the lath and the body  14  held stationary.  
         [0048]     A plurality of insert elements  48  are shown placed in the hollow chamber  32 . The insert elements  48  can be any number of weighted materials such as spherical pellets, small metal scraps, lead shots, or their equivalence. In one embodiment, steel pellets  50  are used for the insert elements  48 . The quantity of steel pellets  50  used is approximately equal to 25% to 70% of the weight of the hammer head  12  with 30% to 60% being more preferred. In another embodiment, tungsten shots are used for their relatively heavier density than steel. Consequently, less space or volume is required for the same weight percentage when tungsten shots are used.  
         [0049]     The insert elements  48  are added to the hollow chamber  32  by individually depositing the steel pellets  50  in through the first opening  40 , before attaching the handle  22  into the open socket  26  and after attaching the impact plate  17  to the end surface  44 . Alternatively, the steel pellets  50  may be added to the hollow chamber by first magnetizing the pellets or gluing the pellets so that they form a single large mass. The single large mass can then be added to the hollow chamber via the second opening  42 , before attaching the impact plate  17  to the end surface  44 . Subsequently, the impact plate  17  may be attached to the end surface  44  by inertia welding, using a vertical standing lath, or by conventional welding. Due to the size of the single large mass, it will not fall out of or fall through the first opening  40  when the welding is taking place. It is understood that if conventional welding is utilized to attach the impact plate  17  to the end surface  44 , the surfaces to be welded should be chamfered to provide a v-groove  35  for welding, See, e.g.,  FIG. 2A .  
         [0050]     Turning now to  FIG. 3 , there is shown an alternative hammer head  12   a  provided in accordance with practice of the present invention. The hammer head includes a single large opening  42  leading into the hollow chamber  32 . The smaller opening has been eliminated from the hammer head  12  shown in  FIG. 2 , but the tail chamber section  36  and the tapered transitional section  38  still incorporated. The hammer head  12   a  may be made by casting or forging the body  14   a  separately from the impact plate  17 . The insert elements  48  may be added to the hollow chamber  32  and the impact plate  17  welded to the end surface  44  of the body  14   a  in the same fashion as discussed above with reference to  FIG. 2 .  
         [0051]     Turning now to  FIG. 4 , there is shown another alternative hammer head  12   b  provided in accordance with practice of the present invention. The hammer head  12   b  includes a single large opening  42  leading into the hollow chamber  32 . The hollow chamber  32  is preferably cylindrical but may take on other or additional contours, such as a slight taper from the large opening  42  towards the back wall  52  of the hollow chamber. The hammer head  12   b  may be made by casting or forging the body  14   b  separately from the impact plate  17 . The insert elements  48  may be added to the hollow chamber  32  and the impact plate  17  welded to the end surface  44  of the body  14   b  in the same fashion as discussed above with reference to  FIG. 2 .  
         [0052]     Turning now to  FIG. 5 , there is shown yet another alternative hammer head  12   c  provided in accordance with practice of the present invention. The hammer head  12   c  includes a single small opening  40  that leads into the hollow chamber  32 , as shown in  FIG. 2 . However, the impact plate  17  is now integrally formed with the body  14   c . The hammer head  14   c  is therefore made from casting only, as further discussed below. The insert elements  48  may be added to the hollow chamber  32  by adding the individual pellets in through the small opening  40  before inserting the handle  22  into the open socket  26 , as discussed above with reference to  FIG. 2 .  
         [0053]      FIG. 5   a  shows still yet another alternative hammer head  12   d  provided in accordance with practice of the present invention. Similar to the other embodiments (i.e.,  FIGS. 1-5 ), the present embodiment preferably includes two openings  33 , one on each of the left and right side surface of the hammer head body  14   d  and each being in communication with the hollow chamber  32 . The impact surface  18  is integrally cast with the body  14   d  and the open socket  26  extends through the body without an opening, like the embodiment of  FIG. 5 . Thus, the insert elements  48  are added to the hollow chamber  32  via the side openings  33  and then subsequently sealed by plugs or caps. Alternatively, the openings  33  may be located along the upper and lower side surfaces of the hammer head body  14   d , and may take on 1 or more than 2 openings. The present embodiment, as well as other embodiments disclosed elsewhere herein, allows a conventional handle with a split attachment portion  24  to be used as it permits a wedge or several wedges to be inserted into the split attachment portion from the top of the open socket to wedge-in or lock-in the handle.  
         [0054]      FIG. 6  is a top plan view of the hammer head  12  of  FIGS. 1-5 . Although shown with the particular impact plate  17 , impact section  16 , open socket, and claw  20 , it is understood that the hammer head  12  may vary in any of these features, and in addition, in length, width, tapered neck section  54 , stepped collar section  56  (located in between the impact section  16  and the tapered neck section), etc. without deviating from the scope the present invention. For example, the present invention may be practiced by varying the metallurgy, the overall hammer head weight, and replacing the claw  20  with another impact section, as further discussed below.  
         [0055]      FIG. 7  is an end view of the hammer head  12  of  FIG. 2  taken at line A-A. As shown, the large opening  42  opens into the hollow chamber  32 , which has a circular chamber surface  58 . The circular chamber surface  58  intersects the transitional section  38 , which connects to the tail chamber section  36 , which terminates into the small opening  40 .  
         [0056]      FIG. 8  is an end view of the impact plate  17  provided in accordance with practice of the present invention. The impact plate  17  includes an impact surface  18  having an array of bumps or serrations  60 , which may be formed from casting, forging, or machining from bar stocks. However, a smooth surface or a dispersed array of bumps may be used instead of the serrated impact surface  18 .  
         [0057]      FIG. 9  is a semi-schematic cross-sectional view of the impact plate  17  of  FIG. 8  taken at line B-B. As evident by  FIG. 9 , a neck or stepped surface on the rear surface  62  of the impact plate  17  is not necessary as a protruding section  46  will form as a by-product of the inertia welding (See, e.g.,  FIG. 2 ).  
         [0058]      FIG. 10  shows an alternative hammer head provided in accordance with practice of the present invention, which is generally designated  64 . The hammer head  64  is commonly found in a sledge hammer. In particular, the hammer head  64  comprises a body  66 , a central open socket  68  (which is shown with a tapered surface but may include a straight surface), and two impact sections  70  with integrally molded impact surfaces  72 . The hammer head  64  further includes two hollow chambers  74 , one in each of the impact sections  70 . Each hollow chamber  74  includes a tapered transition section  76  that leads to a tail chamber section  78  and that leads to an opening  80 . As previously discussed with reference to, for example,  FIGS. 1, 2 , and  5 , the insert elements  48  may be added to each of the hollow chambers  74  by way of the small opening  80 , and preferably in equal amount. As before, the total insert elements should range from about 25% to 70% of the weight of the hammer head  64 , with about 30% to 60% of the total weight being more preferred.  
         [0059]     Although the hammer head  64  is shown with integrally formed impact surfaces  72 , separate impact plates may be used and thereafter welded to the body  66 , as previously discussed with reference to  FIGS. 2-4 . If separate impact plates are used, the small openings  80  may be eliminated from the hammer head  64 , such as that shown in  FIGS. 3 and 4 .  
         [0060]      FIG. 11  is a block flow diagram  82  of an exemplary manufacturing method provided in accordance with practice of the present invention. As shown, the method includes creating a metal die for the hammer head  84 . The metal die for the hammer head can take on any number of configurations, including a hammer head with a single opening, an integral impact surface, a sledge hammer head, a finishing hammer head, or a framing hammer head, just to name a few.  
         [0061]     Next, melted wax is pour into the die to create a wax replica of the hammer head  86 . The wax is then dipped into a slurry bath comprising silica flour and a chemical binder to form an “investment”  88 . After the investment hardens, the wax is removed from the investment by heating the investment and the wax in an oven or a steam chamber  90  to melt the wax. Once the wax is removed, the investment is baked or fired in a heater  92  to cure. Molten metal is then poured into the cured investment  94  to form the cast hammer head.  
         [0062]     Once the cast hammer head sufficiently cools, the investment is removed  96  by impacting the hammer head to break up the investment. The hammer head is now ready to receive the insert elements  98 . As discussed above with reference to  FIGS. 2-5 , if the impact plate is separately produced, the impact plate is then attached to the hammer head via welding. A handle is then attached to the hammer head  100  to complete the deadblow hammer.  
         [0063]      FIG. 12  depicts a metal golf club  102  that incorporates a hollow chamber  104  for receiving insert elements  48 . The golf club head  106  is preferably cast so that the hollow chamber  104  may be formed into the sole  105  of the club head during fabrication. The hosel  107  shown can be any prior art hosel, including an offset hosel or a more conventional hosel for attaching to a shaft. The hollow chamber  104  preferably runs the width of the club face  108  (the direction that is perpendicular to the viewing plane) and is sealed by a cap (not shown). The cap can be attached to the club head  106  by welding. In an exemplary embodiment, steel pellets making up about 10% to 50% of the club head  10  are used to dampen the vibration and the recoil effects of the club head  106  as the club face  108  miss hits and strikes the ground. Exemplary metal golf clubs are disclosed in U.S. Pat. No. 6,344,000, which is incorporated herein by reference.  
         [0064]      FIG. 13  depicts a metal wood golf head  110  that incorporates a hollow chamber  112  for receiving insert elements  48 . The hollow chamber is formed by attaching retaining clips  114  to the club face  116  and to the shell  118  and connecting a hollow tube  120  thereinbetween. Although a hosel is not shown, it is understood that any prior art hosel may be incorporated into the golf club head  110  for attaching to a shaft. Similar to the golf club head of  FIG. 12 , the insert elements  48  preferably make up about 10% to about 50% of the weight of the metal wood  110 . Exemplary metal wood golf clubs are disclosed in U.S. Pat. No. 5,873,791, which is incorporated herein by reference.  
         [0065]      FIGS. 14   a  and  14   b  show an exemplary hammer  200  provided in accordance with aspects of the present invention. The hammer  200  comprises a hammer head  212  and a handle  222 . The hammer head  212  includes a body  214 , a claw  220 , a hollow chamber  232  defined by an impact body section  250 , and an impact plate  217  having an impact surface  218 . The handle  222  has a grip  230  and fits into the opening  226  in the hammer head  212 . As shown, the handle chamber for receiving the handle  222  has a single opening  226 . However, in other embodiments, such as that shown in  FIG. 15   a , the handle chamber has two openings for manipulating the handle to be retained therein, such as for inserting a wedge to retain the handle to the hammer head.  
         [0066]     In a preferred embodiment, the hammer  200  has a single insert element  248  disposed in the hollow chamber  232 . In the embodiment shown in  FIG. 14   a , the insert element  248   a  is cylindrical in shape. In other embodiments, the insert element may be other shapes, such as the spherical insert element  248   b  shown in  FIG. 14   b . In  FIGS. 14   a  and  14   b , the hollow chamber  232  is cylindrical in shape, and therefore a spherical or cylindrical insert element  248   a  or  248   b  is preferred. The cylindrical or spherical insert element can move freely inside the cylindrical hollow chamber  232  without becoming obstructed or deflected by the inside surface of the chamber. For example, when the hammer is swung, the insert element can freely translate and rotate, either at least some or a full 360 degrees, within the chamber. In other embodiments, the chamber may have a different shape, such as a square cross-section, in which case an insert element with a corresponding cross-section may be more preferred.  
         [0067]     The insert element  248   a  may be formed of steel, tungsten, or another suitable metal or high-density material. The weight of the insert element is about 25% to about 70% of the weight of the hammer head  212 , with about 30% to about 60% being more preferred. The insert element  248   a  has a diameter or width that is about 50-95%, and preferably about 70-90%, of the inside diameter or width of the chamber  232 . This relative sizing allows the insert element  248  to carry a large amount of mass without being so large that it rubs or chafes against the inside surface of the chamber when the insert element moves. Thus, the insert element  248  can move back and forth freely within the chamber, but it is still large enough to provide an anti-recoil effect when the hammer  200  is swung. To maximize the mass of the insert element without making it too large to move freely, a solid insert element is preferred.  
         [0068]     The length of the insert element and the chamber may be adjusted according to many variables, including the desired amount of anti-recoil force, the desired amount of recoil the hammer experiences before the anti-recoil force occurs, the mass of the insert element, and the size and shape of the chamber  232 . In the embodiment shown in  FIG. 14   a , the insert element has a length that is approximately half of the inside length of the chamber  232 . The other half of the chamber length provides a space for the insert element  248  to travel to and fro when the hammer is swung and the insert element moves to cancel or minimize the recoil. Said differently, the insert element is configured to move across the chamber  232  to impact the impact plate  217  after the hammer  200  has been struck against a work surface. The delay between the hammer&#39;s impact and the insert element&#39;s impact provides the anti-recoil effect. The empty space left in the chamber  232  allows the insert element to impact the impact plate  217  with a delay. In other embodiments, the insert element may have a length that is less than or more than half of the length of the chamber  232 .  
         [0069]     The single insert element may offer advantages over prior art deadblow hammers comprising a plurality of smaller insert elements. The single insert element  248   a  or  248   b  moves as a whole in one direction when the hammer  200  is swung. The interior surface of the chamber  232  guides the movement of the insert element  248   a  towards the impact plate  217  when the hammer impacts a work surface. Because the insert element  248   a  or  248   b  is a unitary construction body, all of its mass moves toward and impacts the impact plate  217 . When a plurality of insert elements are placed in the chamber, individual elements may be scattered or deflected in transverse directions when the hammer is used. Thus, when such a hammer impacts a work surface, individual impact elements may scatter against each other and cancel out their anti-recoil effect and consequently less than all of the mass inside the chamber moves directly toward and impacts the impact plate  217 . However, when only a single insert element is used, such as that shown in  FIGS. 14   a  and  14   b , all of the mass of the insert element moves in the same direction. This single solid insert element embodiment has been tested and the results have shown a more direct and efficient anti-recoil effect.  
         [0070]     In the embodiment shown in  FIGS. 14   a  and  14   b , the chamber  232  is integral with the hammer head  212  and is opened all the way to the handle  222 . In other embodiments, the chamber is enclosed and is not opened to the handle (see, for example,  FIGS. 15   a  and  15   b ). In  FIGS. 14   a  and  14   b , the insert element  248   a  or  248   b  may be placed inside the chamber through the opening  242  at the front end of the impact body section  250 . The impact plate  217  is then welded or otherwise attached to the end surface  244  of the chamber  232  to close the opening  242 .  
         [0071]      FIG. 15   a  shows another exemplary embodiment of a hammer head  212   a  provided in accordance with practice of the present invention. In this embodiment, the chamber  232  does not open all the way to the handle  222 , but closes off at its end  225 . The chamber  232  is integral with the hammer head  212   a  and may be made by casting, forging, machining, or a combination thereof. The insert element  248   a  is placed into the chamber  232  through the opening  242 , and then the impact plate  217  is welded or otherwise attached to the chamber to close the opening.  
         [0072]      FIG. 15   b  shows another embodiment of a hammer head  212   b  in accordance with practice of the present invention. In this embodiment, a cylindrical impact body section  252  defining a chamber  232  is formed separately from the body  214  of the hammer head  212   b . The impact plate  217  is integrally formed to the cylindrical impact body section  252 . The insert element  248   b  is placed inside the chamber  232  and the cylindrical impact body section  252  is then welded or otherwise attached to the front end surface  227  of the body  214 , thereby sealing the chamber with the insert element  248   b  inside. In one exemplary embodiment, the impact body section  162  is welded to the body  214 . In another embodiment, the impact body section  252  is welded to the body  214  using inertia welding.  
         [0073]      FIG. 16  shows an alternative hammer head  264  provided in accordance with practice of the present invention. The hammer head  264  is commonly found in a sledge hammer. The hammer head  264  comprises two hollow chambers  274 , two insert elements  248   a , and two impact surfaces  272 . A handle  222  is provided in the middle between these pairs of elements. In this embodiment, the chambers  274  and impact plates  272  are integrally formed from a one piece material, with an opening or handle chamber  280  in between them for accommodating the handle  222 . The insert elements  248   a  are placed in their respective chambers, and the handle  222  is inserted into the chamber  280  to seal the two insert element chambers  274 . In other embodiments, the chambers  274  may be formed separately from the impact plates  272 , and the chambers  274  may or may not open to the handle  222 . The insert elements  248   a  may be placed into the chambers  274 , and then the impact surfaces  272  may be welded or otherwise attached to the hammer head  264  to seal the chambers.  
         [0074]      FIG. 17  shows an exemplary deadblow hammer  200 ′, which is described in greater detail in U.S. Pat. No. 6,311,582 B1 to Chow, which is expressly incorporated herein by reference. This embodiment shows a single solid insert element  248   b  incorporated in the hammer head as an improvement over the prior art. The insert element  248   b  is spherical in shape, and the chamber  232  is cylindrical. The insert element  248   b  moves freely and unimpeded through the chamber  232  when the hammer  200  is swung. The size of the insert element relative to the size of the chamber  232  is preferably the same as discussed above with reference to  FIGS. 14   a  and  14   b . In this embodiment, the chamber  232  is not integrally formed with the hammer head  212  but is inserted into the hammer head above the handle  222 .  
         [0075]      FIGS. 18   a  and  18   b  show an exemplary hammer head  212   c , which is described in greater detail in U.S. Pat. No. 4,039,012 to Cook, which is expressly incorporated herein by reference. This embodiment shows a single solid insert element  248   a  as an improvement over the prior art. In this embodiment, the hammer head  212   c  is formed from multiple different components, one of which, the outer body  256 , is integral with the handle  222 . The hammer head  212   c  includes a central bore  229  into which an inner body  258  having a chamber  232  and an integrally formed end piece  259  is placed. The impact plate  217  is threadedly attached, or alternatively welded, at the front of the inner body  258  to close the opening  242  of the chamber  232  and seal the insert element  248   a  inside. The insert element  248   a  and the chamber  232  are cylindrical in shape, although a spherical insert element  248   b  may be used as well. In  FIG. 18   a , the insert element  248   a  has a length that is less than half the length of the chamber  232 , while in  FIG. 18   b  the insert element  248   a  has a length that is greater than half the length of the chamber  232 . The relative lengths of the chamber and insert element may be varied as described above, depending on the desired anti-recoil effect.  
         [0076]      FIG. 19  shows an exemplary hammer head  212   d , which is described in greater detail in U.S. Pat. No. 6,052,885 to Carmien, which is expressly incorporated herein by reference. This embodiment shows a single solid insert element  248   b  as an improvement over the prior art. In this embodiment, the hammer head  212   d  is formed around the chamber  232 . The hammer head  212   d  is shown as it impacts a work surface  219 . The insert element  248   b  moves through the chamber  232  to strike the impact plate  217  when the hammer impacts the work surface  219 . The arrow  275  shows the motion of the hammer head  212   d . As described above, the single insert element  248   b  moves with all of its mass directly toward the impact plate  217  to provide the desired anti-recoil effect.  
         [0077]     Although the preferred embodiments of the invention have been described with some specificity, the description and drawings set forth herein are not intended to be delimiting, and persons of ordinary skill in the art will understand that various modifications may be made to the embodiments discussed herein without departing from the scope of the invention, and all such changes and modifications are intended to be encompassed within the appended claims. Various changes to the hammer head and golf club head may be made including changing the contour, the weight, the hollow chamber configuration, the overall dimensions, incorporating certain aspects of one embodiment into another embodiment provided they are compatible, etc. As another example, rather than a single cylindrical insert element (e.g.,  FIG. 18   a ) or a single spherical insert element (e.g.,  FIG. 19 ), two or more back-to-back cylindrical insert elements or spherical insert elements may be used so long as their relative positions are aligned to minimize deflection upon impact, which would diminish the recoil canceling force discussed above in connection with using a plurality of insert elements. Accordingly, many alterations and modifications may be made by those having ordinary skill in the art without deviating from the spirit and scope of the invention.