BACKGROUND Golf clubs known as wedges are used for short shots to the green, and are configured to provide a relatively high loft on the shot. That is, the head of the wedge, also referred to as the"blade"because it is relatively thin, is angled back from the bottom edge of the club to the top edge of the club relative to the axis of the shaft of the club.

As understood by the present invention, in making golf shots it is important to strike the ball correctly and with the so-called"sweet spot"of the club face, to hit the ball the distance expected by the golfer and to avoid imparting spin to the ball about an axis that will cause the ball to unintentionally curve. An example of a golf club designed to maximize the"sweet spot"area of a golf club face is shown in U. S. Patent No.

5,564,705, which teaches an iron having weights provided along the bottom edge and top edge of the club head to enlarge the sweet spot.

As further understood herein, it is particularly important to hit the ball in the sweet spot when hitting wedge shots, wherein shot control is highly crucial. Unlike the disclosure in the above-referenced patent, however, the present invention has made the critical observation that a golfer, particularly an inexperienced one, will not always strike the ball in the sweet spot of a wedge no matter how enlarged the sweet spot is, because wedge shots are typically hit from many different types of lies, e. g., sand traps, roughs, etc., consequently making it more likely the golfer will strike the ball above or below the sweet spot of the club.

In considering the above observation, the present invention further understands that to prevent a loss of distance when the ball is hit with a wedge above or below the sweet spot of the head, the moment of inertia of a wedge head should be increased about an axis defined by a line between the heel and toe of a club, parallel to the score lines on the face of the club. This axis is referred to herein as the"x axis"or as the"heel to toe axis". More particularly, as understood by the present invention increasing the moment of inertia about the heel to toe axis results in hitting the ball longer distances when the ball is struck above or below the sweet spot. While previous attempts have been made to increase the size of the sweet spot and/or raise or lower the center of gravity of a club head, the observation that raising the moment of inertia about the heel to toe axis improves wedge shot making is believed to be one of the present invention.

SUMMARY OF THE INVENTION A head for a golf club wedge includes a body defining a top region and a sole region opposed to the top region. A cavity is formed in the sole region, with a cavity cover being disposed over the cavity to enclose the cavity. Also, a weight element is established in the top region. With this structure, the moment of inertia of the head is relatively large about a heel to toe axis.

In one preferred embodiment, the body includes a face extending from the sole region to the top region and a back surface opposed to the face and lying between the sole region and top region. Moreover, the top region defines a top back surface, and a first thickness is defined from the face to the back surface. Also, a second thickness greater than the first is defined from the top back surface to the face to thereby establish the weight element. In other words, a thickened top region establishes the weight element in one embodiment.

In this preferred embodiment, curved score lines are formed on the face. More preferably, heel and toe vertical lines are formed on the face generally perpendicular to the score lines, with a first set of score lines extending in a region between the heel of the head and the heel vertical line and a second set of score lines extending in a region between the toe of the head and the toe vertical line. A middle set of score lines extends between the vertical lines. If desired, heel and toe channels are formed in the bottom surface of the head and extend generally perpendicular to the face. The channels are respectively coplanar with the heel and toe vertical lines.

In another embodiment, the body is made of a metal, such as steel, that defines a first density, and the weight element is made of a metal, such as tungsten, that defines a second density greater than the first. More particularly, in this embodiment the top region of the body is formed with plural receptacles and the weight element is established by plural tungsten plugs that are closely received in respective receptacles.

In another aspect, a golf wedge head defines a heel to toe axis and has a moment of inertia about the heel to toe axis of at least one hundred three kilogram-square millimeters (103 kg-mm2).

In still another aspect, a method for making a golf club head includes determining to establish a moment of inertia about a heel to toe axis of a golf club head. The method then includes configuring the head in accordance with the determining act.

The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of the present wedge head showing the face of the club in front elevational view, in an exploded relationship with a golf club shaft; Figure 2 is a cross-sectional view of the head as seen along the line 2-2 in Figure 1; Figure 3 is a perspective view from the back of the head, showing the cavity cover in an exploded relationship with the cavity; Figure 4 is a perspective view of an alternate wedge head; Figure 5 is a cross-sectional view as seen along the line 5-5 in Figure 4; and Figure 6 is a perspective view of the club shown in Figure 4, with the upper weight plugs and cavity cover in an exploded relationship with the body of the head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring initially to Figure 1, a head for a golf club wedge is shown, generally designated 10. As shown, the head includes a steel blade-like body 12 that defines a top region 14 and a sole region 16 that is opposed to the top region 14. Also, the body 12 defines a toe 18 and opposite the toe 18, a heel 20. Connected to and extending upwardly away from the heel 20 is a hosel 22 that can engage a shaft 24 in accordance with means known in the art to establish a golf club, generally designated 26.

Additionally, in cross-reference to Figures 1 and 2, the body 12 defines a bottom edge 28 and a top edge 30. A flat face 32 extends from the sole region 16 to the top region 14, and more particularly extends from the bottom edge 28 to the top edge 30.

Because the club 26 is preferably a wedge, an angle a of at least fifty degrees (50°) and more preferably 56° is established between the face 32 and the axis of the hosel 22.

In accordance with the present invention and as shown in Figures 2 and 3, a cavity 36 is formed in the sole region 16. In the preferred embodiment, the cavity 36 is symmetrically formed about the x axis of the head 10 as shown best in Figure 3.

As also shown in Figures 2 and 3, a cavity cover 38 is disposed over the cavity 36 to enclose the cavity 36 and to complete the sole region 16. Accordingly, the sole region 16 is hollow. The cavity cover 38 is configured like the cavity 36, such that the cavity cover 38 completely covers the cavity 36. As can be appreciated in reference to Figures 2 and 3, the cavity cover 38 defines a sole surface 40 that is flush with a sole surface 42 defined by the body 12 and that, in combination with the sole surface 42, establishes the sole of the head 10. Indeed, when the cavity cover 38 is properly installed and polished the joint between the cavity cover 38 and body 12 is virtually undetectable with the naked eye.

In further accord with the present invention, not only is the cavity 36 provided, but a weight element is established by the top region 14. In the embodiment shown in Figures 2 and 3, a back surface 43 is opposed to the face 32 and is parallel to the face 32. As intended by the present invention, the back surface 43 lies between the sole region 16 and top region 14, and a middle thickness t, is established between the face 32 and back surface 43. Furthermore, the top region 14 defines a top back surface 44. A top thickness t, is established from the top back surface 44 to the face 32, as best shown in Figure 2. As can be seen in Figure 2, the top back thickness t, is greater than the middle thickness t,. Stated differently, the weight element of the head 10 shown in Figures 1-3 is established by a top region 14 that is thicker than the middle portion of the body 12. The top region 14, as shown in Figure 3, extends in an arc along the top edge 30, ramping up from the heel 20 and terminating in an edge wall 14a at the toe 18.

With the above disclosure in mind, it may now be appreciated that the moment of inertia of the head 10 about the x axis shown in Figure 1, i. e., the horizontal axis that is parallel to the club face, that extends through the center of gravity of the club head, and that extends from the heel of the club to the toe of the club parallel to the score lines, is relatively large. In the preferred embodiment, the moment of inertia about the x axis is at least one hundred three kilogram-square millimeters (103 kg-mm2), more preferably is at least one hundred ten kilogram-square millimeters (110 kg-mm2), and most preferably is one hundred nineteen kilogram-square millimeters (119 kg-mm2), the last number representing about a 16% increase about the heel to toe axis moment of inertia relative to conventional wedges.

With such a high moment of inertia about the x axis, tests reveal that by using the head 10 instead of a conventional wedge head, a golfer can expect to add several yards to his or her wedge shots, a critical distance in the context of wedge shots.

Referring back to Figure 1, curved score lines 46 are formed in a middle region 48 of the face 32. At least some of the score lines 46 are gently curved upwardly from their ends toward their midpoints as shown. Further, heel and toe vertical lines 50,52 are formed on the face 32 generally perpendicular to the score lines 46. The vertical lines 50,52 bound the middle region 48. Per the preferred embodiment, a heel set of score lines 54 extends in a heel region 56 located between the heel 20 and the heel vertical line 50, a toe set of score lines 58 extend in a toe region 60 located between the toe 18 and the toe vertical line 52. The heel and toe score lines 54,58 both slope gently down and outwardly like shoulders on the face 32 as shown.

Accordingly, almost the entire face 32 is scored, giving a golfer, particularly a less skilled golfer, more confidence, in that it appears to the golfer that the sweet spot of the club is relatively large. Moreover, owing to their curvature the score lines 46,54, 58 result in a less deleterious ball spin if a golfer strikes a ball with the face 32"open" than would otherwise occur with conventional straight score lines. Still further, the vertical lines 50,52 establish an alignment feature to help a golfer better aline the sweet spot of the head 10 with the ball.

In addition to the above structure, as best shown in Figure 3 the bottom or sole surface 42 is formed with heel and toe channels 62,64 that extend generally perpendicular to the face 32 and that are respectively coplanar with the heel and toe vertical lines 50,52. Accordingly, the vertical lines 50,52 indicate to the golfer where the channels 62,64 are. As provided for herein, the channels 62,64 channel debris and decrease the resistance of the club through, e. g., a rough, further promoting head stability during a stroke and helping the golfer maintain the face 32 square to the ball during impact.

Figures 4-6 show a wedge head, generally designated 100, in accordance with the present invention and intended for a relatively advanced player. As shown, the face 102 includes no vertical lines and traditional straight score lines 104. The head 100 includes a steel body 106 that, as best shown in Figures 5 and 6, defines a top region 108 that is not greatly thickened relative to a middle region 110. Instead, plural, preferably four, relatively dense cylindrically-shaped plugs 112 made of, e. g., tungsten, are closely received in respective receptacles 114 formed in the top region 108 to establish the weight element of the present invention. As shown best in Figure 5, the back surface 116 of each plug 112 is flush with the back surface 118 of the body 106.

Like the head 10 shown in Figures 1-3, the head 100 shown in Figures 4-6 includes a sole region 120 that is centrally formed with a cavity 122. A cavity cover 124 covers the cavity 122. Unlike the cavity cover of the head 10 shown in Figures 1-3, however, the cavity cover 124 does not establish part of the sole surface 126 of the head 100 shown in Figures 4-6; rather, the cavity cover 124 establishes a portion of the back surface 128 of the sole region 120. Accordingly, with the above-disclosed cavity configuration and weight element, the body 106 of the head 100 shown in Figures 4-6, while having an increased moment of inertia about the heel to toe axis, assumes a more traditional wedge configuration preferred by many advanced golfers.

While the particular GOLF CLUB WEDGE HEAD WITH RAISED INERTIA ABOUT HEEL TO TOE AXIS as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and is thus representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean"one and only one"unless explicitly so stated, but rather"one or more". All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U. S. C. §112, sixth paragraph, unless the element is expressly recited using the phrase"means for".