Golf club head with improved striking face

Abstract

A golf club head having a thin-walled face, a thick-walled central region, and a thick peripheral region is further improved by removing unnecessary weight from the peripheral edge of the striking face and localizing the thickened peripheral region only at optimized locations that can benefit from such features.SOLUTION: The striking face 202 is comprised of a thickened central region 214 located near the geometric center of the striking face portion, a central transition region 216 extending radially outward from the thickened central region, a thinned intermediate region 218 extending radially outward from the central transition region, a thickened stress reducing region 220 extending radially outward from the thinned intermediate region, and a thinned peripheral region 222 extending radially outward from the thickened stress reducing region, all of which combine to form an improved striking face.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates generally to golf club heads with improved striking faces, and more particularly to metal wood-type golf club heads having a striking face including a thickened central region located near the geometric center of the striking face portion, a central transition region extending radially outward from the thickened central region, a thinner intermediate region extending radially outward from the central transition region, a thickened stress reduction region extending radially outward from the thinner intermediate region, and a thinner peripheral region extending radially outward from the thickened stress reduction region, which combine to form the improved striking face. [Background technology]

[0002] The striking face of a golf club head is the only part of the golf club head that experiences the highest level of stress when striking a golf ball. Furthermore, because the striking face is the only part that comes into contact with the golf ball, it is one of the most critical components in the design of any golf club.

[0003] To improve the performance of golf club heads through the striking face, golf club designers have attempted to create very thin striking faces, which allow the striking face to elastically deform upon impact with the golf ball, thereby increasing the velocity of the golf ball after it leaves the striking face of the golf club head, while still adhering to the rules of golf. U.S. Patent No. 4,432,549 to Zebelean shows one of the early attempts to thin the striking face of a golf club head by thinning the upper portion of the striking face.

[0004] Thinning the face is not the only way to improve the performance of a golf club head's striking face, and more recent improvements include adjusting the thickness of various portions of the striking face to improve performance. Building on already thin faces, U.S. Patent No. 6,863,626 to Evans et al. illustrates one of the early attempts to vary the thickness of a golf club head's striking face, disclosing that a thicker central region decreases from the center outward to help reduce the speed of the golf ball at the center, creating a larger area of ​​improved speed and performance.

[0005] Further building on the known technology of a thin face combined with a thick central portion, to further improve the performance of golf club heads, U.S. Patent No. 10,758,789 to Bacon et al. adds a thicker peripheral region to the end of the striking face, which the inventors claim improves durability, increases ball speed, and increases characteristic time. However, while this addition is beneficial, it is not optimal because, as shown in U.S. Patent No. 10,758,789, the benefits of the thicker peripheral region are generally localized and do not need to extend all the way to the periphery of the striking face.

[0006] It can therefore be seen that further improvements can be made to a golf club head having a thin face, a thick central region, and a thick peripheral region by removing unnecessary weight from the peripheral edges of the striking face and localizing the thickened peripheral region only in optimized locations that can benefit from such features. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 4,432,549 [Patent Document 2] U.S. Patent No. 6,863,626 [Patent Document 3] U.S. Patent No. 10,758,789 Summary of the Invention

[0008] One aspect of the present invention is a golf club head having a striking face portion positioned at a front portion of the golf club head and adapted to strike a golf ball, and a body portion attached to the rear of the striking face portion, the striking face portion further having a substantially planar front striking surface and an inner back surface, the front striking surface and the inner back surface combined further comprising a thick central region positioned near a geometric center of the striking face portion and having a first thickness, and a thick central region extending from the thick central region by a half-width. the golf club head having a central transition region extending radially outward and having a variable thickness; a thinned intermediate region extending radially outward from the central transition region and having a third thickness; a thickened stress reduction region extending radially outward from the thinned intermediate region and having a fourth thickness; and a thinned peripheral region extending radially outward from the thickened stress reduction region and having a fifth thickness, the thickened stress reduction region forming a ring projecting rearward from the inner rear surface of the striking face portion, the fourth thickness being greater than the first thickness.

[0009] Another aspect of the present invention is a golf club head having a striking face portion positioned at a front portion of the golf club head and adapted to strike a golf ball, and a body portion attached rearward of the striking face portion, the striking face portion further having a substantially planar front striking surface and an inner back surface, the front striking surface and the inner back surface in combination further comprising a thickened central region positioned near a geometric center of the striking face portion and having a first thickness, and a middle portion extending radially outward from the thickened central region and having a variable thickness. the golf club head having a central transition region, a thinned intermediate region extending radially outward from the central transition region and having a third thickness, a thickened stress reduction region extending radially outward from the thinned intermediate region and having a fourth thickness, and a thinned peripheral region extending radially outward from the thickened stress reduction region and having a fifth thickness, the thickened stress reduction region forming a ring projecting rearward from the inner rear surface of the striking face portion, the fifth thickness being less than the fourth thickness, and the third thickness of the thinned intermediate region being the thinnest portion of the striking face portion.

[0010] Another aspect of the present invention is a golf club head having a striking face portion positioned at a front portion of the golf club head and adapted to strike a golf ball, and a body portion attached rearward of the striking face portion, the striking face portion further having a substantially planar front striking surface and an inner rear surface, the front striking surface and the inner rear surface combined to further include an increased stress reduction region positioned around the striking face portion, the increased stress reduction region forming a ring projecting rearwardly from the inner rear surface of the striking face portion, the increased stress reduction region being located a distance between about 15 mm and about 30 mm from the geometric center of the striking face portion, measured across a vertical cross section passing through the geometric center of the striking face portion.

[0011] These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings, description, and claims. [Brief explanation of the drawings]

[0012] The foregoing and other features and advantages of the present invention will become apparent from the following description of the invention as illustrated in the accompanying drawings, which are incorporated herein and form a part of the specification, and which further serve to explain the principles of the invention and enable one skilled in the art to make and use the invention.

[0013] [Figure 1] FIG. 1 of the accompanying drawings shows a front view of a golf club head in accordance with an exemplary embodiment of the present invention, showing section line A-A'. [Figure 2] FIG. 2 of the accompanying drawings shows a cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention taken along section line A-A' shown in FIG. [Figure 3] FIG. 3 of the accompanying drawings shows an enlarged cross-sectional view of the striking face portion of the golf club head in accordance with the exemplary embodiment of the present invention shown in FIG. [Figure 4] FIG. 4 of the accompanying drawings again shows an enlarged cross-sectional view of the striking face portion of the golf club head in accordance with the exemplary embodiment of the present invention shown in FIG. 2, highlighting various features. [Figure 5] FIG. 5 of the accompanying drawings again shows an enlarged cross-sectional view of the striking face of the golf club head in accordance with the exemplary embodiment of the present invention shown in FIG. 2, highlighting various features. [Figure 6] 6a-6l show representative cross-sectional views of thickened stress reduced regions according to exemplary embodiments of the present invention. [Figure 7a] FIG. 7a of the accompanying drawings shows a shaded rear view of a striking face portion of a golf club head in accordance with an exemplary embodiment of the present invention. [Figure 7b] FIG. 7b of the accompanying drawings shows a rear view of the striking face portion of a golf club head in accordance with an exemplary embodiment of the present invention. [Figure 8] FIG. 8 of the accompanying drawings shows a cross-sectional view of a golf club head in accordance with yet another embodiment of the present invention taken along section line A-A' shown in FIG. [Figure 9] FIG. 9 of the accompanying drawings shows an enlarged cross-sectional view of the striking face portion of the golf club head according to another embodiment of the present invention shown in FIG. [Figure 10a] Attached drawing 10a shows a shaded rear view of a striking face of a golf club head in accordance with another embodiment of the present invention. [Figure 10b] FIG. 10b of the accompanying drawings shows a rear view of a striking face portion of a golf club head in accordance with another embodiment of the present invention. [Figure 11] FIG. 11 of the accompanying drawings shows an exploded view of a golf club head in accordance with yet another alternative embodiment of the present invention. [Figure 12] FIG. 12 of the accompanying drawings shows a cross-sectional view of a golf club head in accordance with yet another alternative embodiment of the present invention. [Figure 13] FIG. 13 of the accompanying drawings shows an enlarged cross-sectional view of a striking face portion of a golf club head in accordance with yet another alternative embodiment of the present invention. Detailed Description of the Invention

[0014] The following detailed description sets forth the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

[0015] Various features of the present invention are described below, each of which can be used independently of one another or in combination with other features. However, any single feature of the present invention may not address any or all of the problems discussed above, or may only address one of the problems discussed above. Furthermore, one or more of the problems discussed above may not be fully addressed by any of the features described below.

[0016] FIG. 1 of the accompanying drawings shows a front view of a golf club head 100 in accordance with an exemplary embodiment of the present invention. First and foremost, FIG. 1 of the accompanying drawings shows a coordinate system 101 defining the orientation of the golf club head 100 along the x, y, and z axes. The x-axis shown here is horizontal and extends in a heel-to-toe direction, with the positive axis pointing toward the heel of the golf club head 100. The y-axis shown here is vertical and extends in a crown-to-sole direction. Finally, the z-axis shown here refers to an axis that spans the front-to-back direction on the page, with the positive axis pointing toward the front. This front view of the golf club head 100 shows a striking face portion 102, which in this embodiment further comprises a face insert 104 and a face perimeter 106. FIG. 1 of the accompanying drawings also shows a vertical section line A-A' along the y-axis and along the y-z plane, which allows for a clearer view of the interior shape of the striking face portion 102.

[0017] FIG. 2 of the accompanying drawings shows a cross-sectional view of a golf club head 200 taken along section line A-A' shown in FIG. 1. In this cross-sectional view of the golf club head 200 shown in FIG. 2, it can be seen that the golf club head 200 has a striking face portion 202 and a rear body portion 203 attached to the rear of the striking face portion 202. The striking face portion 202, as defined in this invention, refers to the portion of the golf club head 200 that is substantially planar, located at the front of the golf club head 200, and adapted to strike a golf ball. The striking face portion 202 is manufactured with a thickness defined by a substantially flat forward striking surface 210 and a rear inner surface 212 with a variable contour, forming a striking face portion with a variable face thickness profile. The boundary between the striking face portion 202 and the rear body portion 203 occurs when the rear inner surface 212 deviates from a substantially planar vertical direction toward a substantially horizontal direction.

[0018] 2 of the accompanying drawings finally illustrates that in this embodiment, a face insert 204 is used to close the opening in the striking face portion 202 created by the face perimeter 206. In this embodiment of the invention, the face insert 204 may generally be made from a titanium material to achieve lightweight and durable characteristics, and may be significantly thinner than conventional golf club heads of similar construction due to the unique thickened stress reduction region 216 around the face perimeter 206. In this embodiment of the invention, the thickened stress reduction region 220 around the face perimeter 206 allows the face insert 204 to be thinner and lighter, resulting in a mass of less than about 25 grams, more preferably less than about 24 grams, and most preferably less than about 23 grams, all without departing from the scope and content of the present invention. Compared to a face insert installed without the thickened stress reduction region 220 around the face perimeter 206, the mass of the face insert is reduced by about 12 grams.

[0019] To more fully illustrate the thickened stress reduction region 220 around the face periphery 206, along with the geometry of the remainder of the striking face portion 202, such as the thickened central region 214, central transition region 216, thinned intermediate region 218, and thinned peripheral region 222, an enlarged view of the striking face portion 202 is provided in FIG. 3.

[0020] Figure 3 of the accompanying drawings shows an enlarged cross-sectional view of the striking face portion 202 of the golf club head 200. This enlarged cross-sectional view makes it possible to more clearly show the various heights of the striking face portion 202, while Figure 4 of the accompanying drawings shows the various thicknesses of the striking face portion 202. In accordance with this illustrated exemplary embodiment of the present invention, the striking face portion 202 further includes a thin-walled upper peripheral region 222-a and a thin-walled lower peripheral region 222-b, which combine to form the thin-walled peripheral region 222. The striking face portion 202 has an upper thick-walled stress reduction region 220-a and a lower thick-walled stress reduction region 220-b positioned inward from the thin-walled peripheral region and combine to form the thick-walled stress reduction region 220. In other words, the thick-walled stress reduction region 220 can be said to form a ring that projects rearward from the inner surface 212 of the striking face portion 202. The striking face portion 202 has an upper thinned intermediate region 218-a and a lower thinned intermediate region 218-b positioned inward from the thickened stress reduction regions and combined to form a thinned intermediate region 218. The striking face portion 202 has an upper central transition region 216-a and a lower central transition region 216-b positioned inward from the thinned intermediate regions and combined to form a central transition region 216. Finally, the striking face portion 202 includes a thickened central region 214 positioned inward from the central transition region 214.

[0021] In this embodiment of the invention shown in FIG. 3, the height H1 of the thickened central region 214 is generally between about 4.0 mm and about 15.0 mm, more preferably between about 4.0 mm and about 10.0 mm, and most preferably about 4.0 mm.

[0022] According to this embodiment of the present invention, the height of the central transition region 216 may be greater below the thickened central region 214 than above the thickened central region 214. Thus, according to this embodiment, the height H2-a of the upper central transition region 216-a is between about 7.0 mm and about 11.0 mm, more preferably between about 8.0 mm and about 10.0 mm, and most preferably about 9.0 mm. The height H2-b of the lower central transition region 216-b may generally be between about 13.0 mm and about 17.0 mm, more preferably between about 14.0 mm and about 16.0 mm, and most preferably about 15.0 mm. However, it should be noted that in alternative embodiments, the heights of the upper central transition region 216-a and the lower central transition region 216-b may be the same without departing from the scope and content of the present invention.

[0023] According to this embodiment of the present invention, the height of the thin-walled intermediate region 218 may also be greater below the thick-walled central region 214 than above it. Thus, according to this embodiment, the height H3-a is generally between about 3.5 mm and about 5.5 mm, more preferably between about 4.0 mm and about 5.0 mm, and most preferably about 4.5 mm. The height H3-b of the lower central transition region 218-b may generally be between about 6.5 mm and about 8.5 mm, more preferably between about 7.0 mm and about 8.0 mm, and most preferably about 7.5 mm. Note, however, that in more specific embodiments, the heights of the upper central transition region 218-a and the lower central transition region 218-b may be the same without departing from the scope and content of the present invention.

[0024] The height of the thickened stress reduction region 220, unlike the previous measurements, is the same measurement whether the measurement is for the upper thickened stress reduction region 220-a or the lower thickened stress reduction region 220-b. Thus, according to this embodiment, heights H4-a and H4-b are both about 4.0 mm to about 6.0 mm, more preferably about 4.5 mm to about 5.5 mm, and most preferably about 5.0 mm. Similar to the logic above, having different H4-a and H4-b values ​​does not depart from the scope and content of the present invention, as long as they are both within the above ranges. It is worth noting here that the height of the thickened stress reduction region 220 is critical to the proper functioning of the present invention, as it carefully balances the desire to avoid excessively adding unnecessary mass to the striking face portion 202 with the desire to provide sufficient structural rigidity to reduce stress from the face perimeter 106 (shown in FIG. 1 ), allowing the remainder of the striking face portion 202 to be thinner and more efficient. The height of the thickened stress reduced region 220, combined with the thickness of the thickened stress reduced region 220 (described below in FIG. 4), outlines an optimized shape that achieves the performance enhancements of the present invention.

[0025] Before moving on to a discussion of the thin peripheral region 222, it is important to note that the location of the thick stress reduction region 220 relative to the geometric face center 108 (shown in FIG. 1) is critical to achieving the performance enhancements of the present invention. This is particularly true along a vertical cross-sectional plane passing through the geometric face center 108 (shown in FIG. 1), as depicted in the enlarged cross-sectional view shown in FIG. 3. The importance of this particular cross-section, and the location of the thick stress reduction region 220 along this cross-section, stems from the tendency of the striking face portion 202 to achieve a higher stress enhancement in the upper face portion along this plane, thus adding the thick stress reduction region 220. In this embodiment of the invention, the thickened stress reduction region 220 may generally be positioned along cross-section A-A' at a distance of about 15 mm to about 30 mm from the geometric surface center 105, preferably about 17 mm to about 28 mm from the geometric surface center 105 (shown in FIG. 1) along cross-section plane A-A', and most preferably between about 20 mm and about 25 mm from the geometric surface center 105 (shown in FIG. 1) along cross-section plane A-A'.

[0026] The height of the thin-walled peripheral region 222 may also be greater below the thick-walled central region 214 than above it. Thus, according to this embodiment, height H5-a may be between about 1.8 mm and about 2.8 mm, more preferably between about 2.1 mm and about 2.5 mm, and most preferably about 2.3 mm. Height H5-b may generally be between about 2.3 mm and about 3.3 mm, more preferably between about 2.6 mm and about 3.0 mm, and most preferably about 2.8 mm. Note, however, that in alternative embodiments, the heights of the upper thin-walled peripheral region 222-a and the lower thin-walled peripheral region 222-b may be the same without departing from the scope and content of the present invention.

[0027] 4 of the accompanying drawings shows another enlarged cross-sectional view of the striking face portion 202 of the golf club head 200. In this cross-sectional view, the various thicknesses of the components of the striking face portion 202 are shown in more detail. In this current embodiment of the invention, the thickened central region 214 may generally have a thickness T1 of less than about 3.6 mm, more preferably less than about 3.4 mm, and most preferably less than about 3.2 mm, as an objective of the present invention is to minimize the thickness of the various components of the striking face portion 202 through the introduction of thickened stress reduction regions 220 that relieve stress on the striking face portion 202.

[0028] The thickness of the thinned intermediate region 218 may be generally the same regardless of whether it is located in the upper thinned intermediate region 218-a or the lower thinned intermediate region 218-b. Thus, thicknesses T3-a and T3-b are both less than about 2.5 mm, more preferably less than about 2.4 mm, and most preferably less than about 2.3 mm. However, in alternative embodiments of the present invention, the values ​​of T3-a and T3-b may be slightly different from each other without departing from the scope and content of the present invention as long as they are both within the above ranges.

[0029] The thickness of the thickened stress reduction regions 220, shown here as upper thickened stress reduction region 220-a having thickness T4-a and lower thickened stress reduction region 220-b having thickness T4-b, combined with the width of the thickened stress reduction regions 220, defines a geometric shape that is important for improved performance of the striking face portion 202 of the golf club head. In this embodiment, the thicknesses T4-a and T4-b of the upper thickened stress reduction region 220-a and lower thickened stress reduction region 220-b, respectively, are both the same and therefore are between about 3.6 mm and about 4.4 mm, more preferably between about 3.8 mm and about 4.2 mm, and most preferably about 4.0 mm. However, in other embodiments of the present invention, the thicknesses T4-a and T4-b may deviate slightly from one another without departing from the scope and content of the present invention, provided they do not fall outside the thickness ranges defined above.

[0030] Once the thickness T4 and height H4 of the thickened stress reduced region 220 are defined, a preferred geometry for the thickened stress reduced region 220 can be established as a ratio of thickness to height. The preferred geometry has a T to H ratio defined by the following equation (1): T-to-H ratio = (thickness of the thick stress-reduced region T4) / (height of the thick stress-reduced region H4) ---Formula (1) The T-to-H ratio of the increased stress reduction region 220 of the striking face portion 202 according to the present invention may generally be between about 0.6 and about 1.1, more preferably between about 0.7 and about 0.9, and most preferably about 0.8. Again, as discussed above, this ratio is important for achieving the stress reduction properties of the striking face portion 202 while minimizing unnecessary mass added by the addition of the increased stress reduction region 220.

[0031] The thickness of the thinned peripheral region 222 may be generally the same regardless of whether it is located in the upper thinned peripheral region 222-a or the lower thinned peripheral region 222-b. Thus, thicknesses T5-a and T5-b are both less than about 3.0 mm, more preferably less than about 2.8 mm, and most preferably less than about 2.7 mm. However, in alternative embodiments of the present invention, the values ​​of T5-a and T5-b may be slightly different from each other without departing from the scope and content of the present invention, as long as they are both within the aforementioned ranges.

[0032] Another important relationship worth highlighting here is the thickness T1 of the thickened central region 714 relative to the thickness T4 of the thickened stress reduction region 720. Because the introduction of the thickened stress reduction region 720 significantly reduces the overall thickness and mass of the entire striking face portion 702, the resulting relationship between the two thicknesses is critical to achieving the improved performance of the present invention. In this exemplary embodiment of the present invention, the ratio of T4 divided by T1 is generally greater than about 1, more preferably greater than about 1.15, and most preferably greater than about 1.375. Stated another way, the thickness T4 of the thickened stress reduction region 220 can be said to be greater than the thickness T1 of the thickened central region 214 or any other location along the entire striking face portion 202. The thickest portion of the striking face portion 202 is located on the thickened stress reduction region 220.

[0033] FIG. 5 of the accompanying drawings shows an enlarged cross-sectional view of the striking face portion 202 of the golf club head 200 similar to FIGS. 3 and 4, but this time focusing on the transition from the thicker stress reduction region 220 to the adjacent thinner intermediate region 218 and thinner peripheral region 222. In this embodiment of the invention, the various radii around the thicker stress reduction region 220 are also important to the proper functioning of the invention, as an undesirable radius not only defeats the purpose of reducing stress, but can also add manufacturing challenges. Above all, the radii must minimize the unwanted weight addition due to the addition of the thicker stress reduction region 220, on the one hand, and balance the stresses and manufacturing challenges caused by the thicker stress reduction region 220, on the other hand.

[0034] Radius R5-a and radius R5-b represent the radius of curvature, or blend, from thicker stress reduction regions 220-a and 220-b to thinner peripheral regions 222-a and 222-b. R5-a and R5-b in this embodiment may generally be the same number and generally range from about 1.0 mm to about 1.4 mm, more preferably from about 1.1 mm to about 1.3 mm, and most preferably about 1.2 mm. However, it should be noted that in other embodiments of the present invention, R5-a and R5-b may be different from each other as long as they fall within the radius ranges described above without departing from the scope and content of the present invention.

[0035] Radius R3-a and radius R3-b represent the radius of curvature, or blend, from the thicker stress reduction regions 220-a and 220-b to the thinner intermediate regions 218-a and 218-b. R3-a and R3-b in this embodiment may generally be the same or may be the same as R5-a and R5-b described above, and may be between about 1.0 mm and about 1.4 mm, more preferably between about 1.1 mm and about 1.3 mm, and most preferably about 1.2 mm. Note, however, that in other embodiments of the present invention, R3-a and R3-b may be different from one another as long as they fall within the radius ranges described above without departing from the scope and content of the present invention.

[0036] It is instructive to note here that the radii of blends from the thicker stress reduction region 220 to the thinner peripheral region 222 and the thinner intermediate region 218, designated R5 and R3, respectively, may generally be the same as one another. However, as noted above, in other embodiments of the invention, these numbers may be different from one another as long as they are within the ranges set forth above without departing from the scope and content of the invention.

[0037] Figures 6a through 6L of the accompanying drawings show alternative shapes for the thickened stress reduction region 220. Referring to Figure 6a, a substantially rectangular design similar to the previously described design with the addition of a transition radius is shown. Figure 6b of the accompanying drawings shows an alternative outwardly tapered design for the thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. Figure 6c of the accompanying drawings shows another inwardly tapered design for the thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. Figure 6d of the accompanying drawings shows an alternative outwardly tapered design for the thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. Figure 6e of the accompanying drawings shows an alternative outwardly tapered design for the thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. Figure 6f of the accompanying drawings shows an alternative outwardly tapered design for the thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. FIG. 6g of the accompanying drawings illustrates an alternative triangular chevron design for thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. FIG. 6h of the accompanying drawings illustrates an alternative inwardly offset triangular chevron design for thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. FIG. 6i of the accompanying drawings illustrates an alternative outwardly offset triangular chevron design for thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. FIG. 6j of the accompanying drawings illustrates an alternative hemispherical design for thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. FIG. 6k of the accompanying drawings illustrates an alternative organic design for thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention. FIG. 6l of the accompanying drawings illustrates an alternative tapered recess channel design for thickened stress reduction region 220 in accordance with an alternative embodiment of the present invention.

[0038] 7a and 7b show rear views of a striking face portion 702 of a golf club head in accordance with an exemplary embodiment of the present invention. In FIG. 7a, a shaded view is provided to better visualize the various components of the striking face portion 702. In FIG. 7a, a thinned peripheral region 722 forms the perimeter of the striking face portion 702. Inward from the thinned peripheral region 722, a thickened stress reduction region 720 can be seen. Inward from the thickened stress reduction region 720 is a thinned intermediate region 718. Finally, at the geometric center of the striking face portion 702 is a thickened central region 714. In addition to showing the various components of the striking face portion 701, FIG. 7a also shows how the heights of the various components vary depending on where they are located on the face; previous measurements of the heights of the various components referenced only a cross-section along the geometric center of the face, as shown in FIG. 1. In one example, the height of the intermediate transition region 718 is generally found to be less at the crown and sole portions of the striking face portion 702 compared to the height of the intermediate transition region 718 at the heel and toe portions of the striking face portion 702 .

[0039] To better illustrate the differences in height of the various components along various portions of the face, FIG. 7b shows an unshaded rear view of the striking face portion 702. In addition to the above, FIG. 7b allows for a more detailed depiction of the radial distances of the various components, since all measurements are taken from the face's geometric center 108 (shown in FIG. 1). This is similar to the above discussion regarding the location of the thickened stress reduced region 220 in FIG. 2. However, the distances provided here are not constrained to a particular cross-section A-A', as in the previous discussion in FIG. 2, but rather are measurements of minimum and maximum radial distances. In this rear view of the striking face portion 702 shown in FIG. 7b, it can be seen that the outer periphery of the thickened central region 714 is generally located within a projected distance D1 of between about 4.00 mm and about 14.0 mm from the geometric face center in any radial direction. The outer periphery of the central transition region 716 may generally be positioned at a distance D2 between about 13.0 mm and about 30.0 mm from the geometric face center in any radial direction. The outer periphery of the thinned intermediate region 718 may generally be positioned at a distance D3 between about 17.0 mm and about 40.0 mm from the face center in any radial direction. The outer periphery of the thickened stress reduction region 720 may generally be positioned at a distance D4 between about 15.0 mm and about 46.0 mm from the face center in any radial direction. Finally, the outer periphery of the thinned peripheral region 722 may generally be positioned at a distance D5 between about 25.50 mm and about 55.5 mm from the face center in any radial direction.

[0040] Figure 8 of the accompanying drawings shows a cross-sectional view of a golf club head 800 in accordance with an alternative embodiment of the present invention, taken along section line A-A' shown in Figure 1. In this cross-sectional view of the present invention, the shape and geometry of the upper, thickened stress reduction region 820-a is modified differently from the lower, thickened stress reduction region 820-b to generally help address the high stress levels generated in the upper crown region of the striking face portion 802. An enlarged view of the striking face portion 802 is provided in Figure 9 to illustrate the difference in blend height and radius of curvature between the upper, thickened stress reduction region 820-a and the lower, thickened stress reduction region 820-b.

[0041] FIG. 9 of the accompanying drawings shows an enlarged cross-sectional view of the striking face portion 802 of the golf club head 800 shown in FIG. 8. In this enlarged cross-sectional view, only the features that distinguish this embodiment of the present invention from the previous embodiment are highlighted. In this alternative embodiment of the present invention, the height H4-a of the upper, thicker stress reduction region 820-a is no longer the same as the height H4-b of the lower, thicker stress reduction region 820-b. In fact, the height H4-a of the upper, thicker stress reduction region 820-a is reduced to address stress risers that often occur at the top of the striking face portion 802. As the upper stress reduction region 820-a becomes thicker, the height H3-a of the upper, thinner intermediate region 818-a increases. In addition to the above, to further reduce stress, the radius R3-a between the upper, thicker stress reduction region 820-a and the upper, thinner intermediate region 818-a is increased to create a more gradual blend at this location. Finally, regardless of addressing stress levels in the striking face portion 802, the radius R5-a between the upper, thicker stress reduction region 820-a and the upper, thinner peripheral region 822-a may also be increased to soften the blend and facilitate manufacturability.

[0042] Breaking down the numbers, the height H4-a of the upper, thicker stress reduction region 820-a according to this embodiment of the invention may generally be between about 3.1 mm and about 3.9 mm, more preferably between about 3.3 mm and about 3.7 mm, and most preferably about 3.5 mm, which is about 0.5 mm shorter than the corresponding portion H4-b located in the lower, thicker stress reduction region 820-b. The height H3-a of the upper, thinner intermediate region 818-a according to the current embodiment of the invention may generally be between about 6.5 mm and about 8.5 mm, more preferably between about 7.0 mm and about 8.0 mm, and most preferably about 7.5 mm, making it approximately the same as the corresponding portion H3-b located in the lower, thinner intermediate region 818-b.

[0043] In addition to the height change, the radii R3-a and R5-a of the upper, thickened stress reduction region 820-a are also modified to differ from the corresponding portions of the lower, thickened stress reduction region 820-b. Increasing the radius of curvature of R3-a creates a more gradual transition between the two adjacent components, helping to eliminate stress buildup that may occur in that portion of the striking face portion 802. R3-a according to this embodiment of the invention may generally be greater than about 1.50 mm, more preferably greater than about 1.60 mm, and more preferably greater than about 1.70 mm. On the other hand, the radius of curvature R5-a is also increased to be more gradual, but this time to account for the less noticeable areas of reduced casting flow for manufacturing reasons. Therefore, R5-a according to this embodiment of the invention may generally be greater than about 1.50 mm, more preferably greater than about 1.60 mm, and more preferably greater than about 1.70 mm. It is therefore worth noting here that in this embodiment, it is important that the radius of curvature of the transition of the upper, thickened stress reduced region 820-a be greater than the radius of curvature of the transition of the lower, thickened stress reduced region 820-b, since striking face portion 802 often exhibits higher stress levels at that location.

[0044] 10a and 10b show rear views of a striking face portion 1002 of a golf club head according to an exemplary embodiment of the present invention. In FIG. 10a, a shaded view is provided to provide a better visualization of the various components of the striking face portion 1002. In the shaded view shown in FIG. 10a and the wireframe view shown in FIG. 10b, an adjustment to the upper, thickened stress reduction region 1020-a can be seen, with its height H4-a (shown in FIG. 9) being smaller compared to the remainder of the thickened stress reduction region 1020-a. Another thing worth noting here, not previously mentioned, is that in the current exemplary embodiment of the present invention, the entire thickened stress reduction region 1020 takes the shape of a ring surrounding a central portion of the striking face portion 1002. However, in alternative embodiments of the present invention, the thickened stress reduction region 1020 need not completely surround the striking face portion 1002 but may partially surround the striking face portion without departing from the scope and content of the present invention. Stated another way, the thickened stress reduction region 1020 may encompass less than 360 degrees around the face, less than about 270 degrees around the face, or less than 180 degrees around the face, all without departing from the scope and content of this invention.

[0045] Figures 11 through 15 of the accompanying drawings show golf club heads in accordance with further embodiments of the present invention, in which the thickened stress reduction regions are formed from multiple materials to achieve further improved stress reduction capabilities of the thickened stress reduction regions.

[0046] 11 of the accompanying drawings shows an exploded perspective view of a golf club head 1100 in accordance with yet another embodiment of the present invention, where the thickened stress reduction region is further formed from multiple materials. In this exploded cross-sectional view of the golf club head 1100 shown in FIG. 11, the body portion 1103 has a pocket 1134 with a peripheral ledge 1132 that helps to receive a gasket 1130 that separates the face insert 1104 from the peripheral ledge 1132, as shown in FIG. 11. In this embodiment of the present invention, the combination of the peripheral ledge 1132, the gasket 1130, and the periphery of the face insert 1104 combine to create the thickened stress reduction region (shown in FIG. 12).

[0047] [FIG. 12 of the accompanying drawings shows a cross-sectional view of a golf club head 1200 in accordance with an alternative embodiment of the present invention, taken along section line A-A' shown in FIG. 1. In this cross-sectional view of the golf club head 1200, it can be seen that the golf club head 1200 can be divided into a front striking face portion 1202 and a rear body portion 1203, similar to the previous embodiment. The front striking face portion 1202 further comprises an open pocket 1234 adapted to receive a face insert 1204, as in the previous embodiment. However, in this embodiment of the present invention, instead of welding the face insert 1204 directly around the perimeter of the pocket 1234, as is commonly known in the industry, the open pocket 1234 creates a peripheral ledge 1232 recessed from the outer surface of the striking face, and the peripheral ledge 1232 is adapted to receive a gasket 1230 that separates the face insert 1204 from the peripheral ledge 1232.] In this cross-sectional view of the invention, it can be clearly seen that the combination of peripheral ledge 1232, gasket 1230, and the periphery of face insert 1204 combine to create thickened stress reduced region 1220. Thickened stress reduced region 1220 in this embodiment may be further defined as upper thickened stress reduced region 1220-a and lower thickened stress reduced region 1220-b, both of which have similar dimensional measurements as the previous embodiments described above.

[0048] In this embodiment of the invention, the face insert 1204, gasket 1230, and peripheral ledge 1232 may generally be bonded together using some type of adhesive. However, in alternative embodiments of the invention, the three components forming the thickened stress reduced region 1220, which may have different material properties, may rely on various bonding techniques, such as brazing, swaging, or mechanical fasteners, all without departing from the scope and content of the invention, so long as the face insert 1204 is not directly bonded to the peripheral ledge 1232 itself.

[0049] The material used to construct gasket 1230 is also important in this embodiment of the invention and can help reduce stress around the front striking face portion 1202. In this embodiment, the material used to construct the gasket may generally have a modulus of elasticity, or Young's modulus, of between about 5 GPa and about 120 GPa, more preferably between about 10 GPa and about 80 GPa, and most preferably about 30 GPa. In addition to the above, gasket 1230 may also have a density of less than about 2,000 g / cc, more preferably less than about 1,900 g / cc, and most preferably less than about 1,800 g / cc, all without departing from the scope and content of the present invention.

[0050] To illustrate some of the dimensions of the gasket 1230 itself, an enlarged cross-sectional view of the striking face portion 1202 is shown in FIG. 13. In this view, it can be seen that the gasket 1230 can have approximately equal upper and lower gasket heights H6-a and H6-b. H6-a and H6-b, according to this embodiment of the invention, can generally be between about 3.0 mm and about 7.0 mm, more preferably between about 4.0 mm and about 6.0 mm, and most preferably about 5.0 mm. FIG. 13 also shows the gasket thickness T6, designated as upper gasket thickness T6-a and lower gasket thickness T6-b, both of which are approximately equal in this embodiment of the invention. Therefore, T6-a and T6-b, according to this embodiment of the invention, can generally be between about 0.3 mm and about 0.7 mm, more preferably between about 0.4 mm and about 0.6 mm, and most preferably about 0.5 mm.

[0051] Based on the thickness and height measurements described above, it can be said that the gasket 1230 may have a T to H ratio defined by equation (2) below: T to H ratio = (gasket thickness T6) / (gasket height H6) - (2) The T to H ratio of the gasket 1230 may generally be between about 0.04 and about 0.23, more preferably between about 0.06 and about 0.15, and most preferably about 0.1.

[0052] It should also be noted that while the thickness and height of the gasket 1230 are the same for the upper portion of the gasket 1230 and the lower portion of the gasket 1230, the thickness and height of the gaskets may differ from one another without departing from the scope and content of the present invention. In one exemplary embodiment, the upper portion of the gasket 1230 may be thicker and the lower portion of the gasket 1230 may be thinner to allow the striking face portion 1202 to flex more downward upon impact with the golf ball, helping to reduce downward launch and spin, without departing from the scope and content of the present invention. Of course, when manipulating the thickness of the gasket 1230, the depth of the perimeter ledge 1232 is typically adjusted accordingly to create a seamless, flat appearance for the golf club head in the rest neutral position. Alternatively, the thickness of the material can be maintained, but the modulus of elasticity adjusted to achieve the same effect without departing from the scope and content of the present invention.

[0053] It should be noted that while most of the embodiments described herein are directed to creating a releasable hosel hole cover, all of these embodiments may include adhesive to keep the hosel hole cover in the hosel hole, making the hosel hole cover non-removable, without departing from the scope and content of this invention.

[0054] Except in the working examples, or unless otherwise expressly stated, all numerical ranges, quantities, values, and percentages in the preceding specification, such as amounts of material, moments of inertia, center of gravity locations, lofts, draft angles, various performance ratios, etc., may be understood as if preceded by the term "about," even if the term "about" does not explicitly appear in the value, quantity, or range. Accordingly, unless otherwise indicated, the numerical parameters set forth in the foregoing specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of, at least the number of reported significant digits and by applying ordinary rounding techniques.

[0055] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, such numerical values ​​inherently contain certain errors resulting from the standard deviation found in their respective testing measurements. Further, when numerical ranges of various scopes are set forth herein, it is noted that any combination of these values ​​inclusive of the recited values ​​may be used.

[0056] Of course, it will be understood that the foregoing description relates to exemplary embodiments of the present invention and that modifications can be made without departing from the spirit and scope of the present invention as set forth in the following claims. The technical features described here are listed below. [Technical feature 1] In the golf club head, a striking face portion located on a front portion of the golf club head and adapted to strike a golf ball; a body portion attached rearwardly of the striking face portion; The hitting face portion further comprises: a substantially planar front striking surface; an interior back surface; The front striking surface and the inner rear surface in combination further comprise: a thickened central region located near a geometric center of the striking face portion, the thickened central region having a first thickness; a central transition region extending radially outward from the thickened central region and having a variable thickness; a thinned intermediate region extending radially outward from the central transition region, the thinned intermediate region having a third thickness; a thickened stress reduction region extending radially outward from the thinned intermediate region, the thickened stress reduction region having a fourth thickness; a thinned peripheral region extending radially outward from the thickened stress reduction region, the thinned peripheral region having a fifth thickness; the thickened stress reduced region forms a ring projecting rearwardly from the inner rear surface of the striking face portion; The fourth thickness is greater than the first thickness. [Technical feature 2] 2. The golf club head according to claim 1, wherein the fourth thickness of the thickened stress reduction region is the thickest portion of the striking face portion. [Technical feature 3] The golf club head according to Technical Feature 2, wherein the fifth thickness is greater than the third thickness. [Technical feature 4] The thickened stress reduced region has a T to H ratio of between about 0.6 and about 1.1, the T to H ratio being defined as: T-to-H ratio = (fourth thickness T4 of thick-walled stress reduced region) / (height H4 of thick-walled stress reduced region) A golf club head according to Technical Feature 1. [Technical feature 5] 5. The golf club head according to claim 4, wherein the T to H ratio is between about 0.7 and about 0.9. [Technical feature 6] 6. The golf club head according to Technical Feature 5, wherein the T to H ratio is about 0.8. [Technical feature 7] The thickened stress reduced region further comprises: an upper thick-walled stress reduction region; a lower thickened stress reduction region; 5. The golf club head according to claim 4, wherein the upper thick-walled stress reduction area and the lower thick-walled stress reduction area have the same height. [Technical feature 8] The thickened stress reduced region further comprises: an upper thick-walled stress reduction region; Lower thick-walled stress-reducing area, The golf club head according to Technical Feature 4, wherein the upper thick-walled stress reduction area and the lower thick-walled stress reduction area have different heights. [Technical feature 9] The golf club head according to Technical Feature 8, wherein the height of the stress reduction region of the upper thickness is smaller than the height of the stress reduction region of the lower thickness. [Technical feature 10] 10. The golf club head according to claim 9, wherein the height of the upper thickened stress reduction area is approximately 0.5 mm less than the height of the lower thickened stress reduction area. [Technical feature 11] In the golf club head, a striking face portion located on a front portion of the golf club head and adapted to strike a golf ball; a body portion attached rearwardly of the striking face portion; The hitting face portion further comprises: a substantially planar front striking surface; an interior back surface; The front striking surface and the inner rear surface in combination further comprise: a thickened central region located near a geometric center of the striking face portion, the thickened central region having a first thickness; a central transition region extending radially outward from the thickened central region and having a variable thickness; a thinned intermediate region extending radially outward from the central transition region, the thinned intermediate region having a third thickness; a thickened stress reduction region extending radially outward from the thinned intermediate region, the thickened stress reduction region having a fourth thickness; a thinned peripheral region extending radially outward from the thickened stress reduction region, the thinned peripheral region having a fifth thickness; the thickened stress reduced region forms a ring projecting rearwardly from the inner rear surface of the striking face portion; the fifth thickness is smaller than the fourth thickness; The golf club head, wherein the third thickness of the thin-walled intermediate region is the thinnest part of the striking face portion. [Technical feature 12] 12. The golf club head according to claim 11, wherein the fourth thickness of the thick stress reduction region is the thickest portion of the striking face portion. [Technical feature 13] 13. The golf club head of claim 12, wherein the thickened stress reduction region is located at a distance of about 15.0 mm to about 46.0 mm from the geometric center of the striking face portion, measured along a radial direction. [Technical feature 14] 14. The golf club head of claim 13, wherein the thickened stress reduction region is located at a distance between about 15 mm and about 30 mm from the geometric center of the striking face portion, measured across a vertical cross section through the geometric face center. [Technical feature 15] 15. The golf club head of claim 14, wherein the thickened stress reduction region is located at a distance between about 17 mm and about 28 mm from the geometric center of the striking face portion, measured across a vertical cross section through the geometric face center. [Technical feature 16] 16. The golf club head of claim 15, wherein the thickened stress reduction region is located at a distance between about 20 mm and about 25 mm from the geometric center of the striking face portion, measured across a vertical cross section through the geometric face center. [Technical feature 17] In the golf club head, a striking face portion located on a front portion of the golf club head and adapted to strike a golf ball; a body portion attached rearwardly of the striking face portion; The hitting face portion further comprises: a substantially planar front striking surface; an interior back surface; the front striking surface and the inner rear surface in combination further include an increased thickness stress reduction region positioned about the periphery of the striking face portion; the thickened stress reduced region forms a ring projecting rearwardly from the inner rear surface of the striking face portion; the thickened stress reduced region is located a distance between about 15 mm and about 30 mm from the geometric center of the striking face portion, measured across a vertical cross section passing through the geometric center of the striking face portion. [Technical feature 18] The thickened stress reduced region has a T to H ratio of between about 0.6 and about 1.1, the T to H ratio being defined as: T-to-H ratio = (fourth thickness T4 of thick-walled stress reduced region) / (height H4 of thick-walled stress reduced region) 18. A golf club head according to claim 17. [Technical feature 19] 19. The golf club head according to claim 18, wherein the T to H ratio is between about 0.7 and about 0.9. [Technical feature 20] 20. The golf club head according to claim 19, wherein the T to H ratio is about 0.8. [Explanation of symbols]

[0057] 100 golf club heads 101 Coordinate System 102 hitting face part 104 Face Insert 105 Geometric surface center 106 Face Circumference 108 Geometric Face Center 200 golf club heads 202 hitting face part 203 Rear main body part 204 Face Insert 206 Face Circumference 210 forward hitting face 212 Posterior inner surface 214 Central area 216 Central transition region 218 Intermediate area 220 Stress reduction area 222 Surrounding Area 702 hitting face part 714 Central area 716 Central Transition Region 718 Thin intermediate area 720 Stress reduction area 722 Thin-walled surrounding area

Claims

1. In the golf club head, a striking face portion located on a front portion of the golf club head and adapted to strike a golf ball; a body portion attached rearwardly of the striking face portion; The hitting face portion further comprises: a substantially planar front striking surface; an interior back surface; The front striking surface and the inner rear surface in combination further comprise: a thickened central region located near a geometric center of the striking face portion and having a first thickness; a central transition region extending radially outward from the thickened central region and having a variable thickness; a thinned intermediate region extending radially outward from the central transition region, the thinned intermediate region having a third thickness; a thickened stress reduction region extending radially outward from the thinned intermediate region, the thickened stress reduction region having a fourth thickness; a thinned peripheral region extending radially outward from the thickened stress reduction region, the thinned peripheral region having a fifth thickness; the thickened stress reduction region rises rearwardly from the inner rear surface of the striking face portion at both its boundary with the thinned intermediate region and its boundary with the thinned peripheral region, thereby forming an open ring projecting rearwardly from the inner rear surface of the striking face portion, the thickness of the open ring of the thickened stress reduction region being greater than the thickness of the thinned peripheral region and the thickness of the thinned intermediate region, and the thickened stress reduction region displaces about the thinned peripheral region when subjected to a force from the thinned intermediate region; The fourth thickness is greater than the first thickness.

2. 2. The golf club head of claim 1, wherein the fourth thickness of the thickened stress reduced region is the thickest portion of the striking face portion.

3. The golf club head of claim 2 , wherein the fifth thickness is greater than the third thickness.

4. The thickened stress reduced region has a T to H ratio of between 0.6 and 1.1, the T to H ratio being defined as: T-to-H ratio=(fourth thickness T4 of thick stress reduced region) / (height H4 of thick stress reduced region) The golf club head according to claim 1 .

5. 5. The golf club head of claim 4, wherein the T to H ratio is between 0.7 and 0.

9.

6. 6. The golf club head of claim 5, wherein the T to H ratio is 0.

8.

7. The thickened stress reduced region further comprises: an upper thick-walled stress reduction region; a lower thickened stress reduction region; 5. The golf club head of claim 4, wherein the upper thickened stress relief area and the lower thickened stress relief area have the same height.

8. The thickened stress reduced region further comprises: an upper thick-walled stress reduction region; Lower thick-walled stress-reducing area, 5. The golf club head of claim 4, wherein the upper thickened stress relief area and the lower thickened stress relief area have different heights.

9. 9. The golf club head of claim 8, wherein the height of the upper thickened stress relief region is less than the height of the lower thickened stress relief region.

10. 10. The golf club head of claim 9, wherein the height of the upper, thickened stress reduction region is 0.5 mm less than the height of the lower, thickened stress reduction region.

11. In the golf club head, a striking face portion located on a front portion of the golf club head and adapted to strike a golf ball; a body portion attached rearwardly of the striking face portion; The hitting face portion further comprises: a substantially planar front striking surface; an interior back surface; The front striking surface and the inner rear surface in combination further comprise: a thickened central region located near a geometric center of the striking face portion and having a first thickness; a central transition region extending radially outward from the thickened central region and having a variable thickness; a thinned intermediate region extending radially outward from the central transition region, the thinned intermediate region having a third thickness; a thickened stress reduction region extending radially outward from the thinned intermediate region, the thickened stress reduction region having a fourth thickness; a thinned peripheral region extending radially outward from the thickened stress reduction region, the thinned peripheral region having a fifth thickness; the thickened stress reduction region rises rearwardly from the inner rear surface of the striking face portion at both its boundary with the thinned intermediate region and its boundary with the thinned peripheral region, thereby forming an open ring projecting rearwardly from the inner rear surface of the striking face portion, the thickness of the open ring of the thickened stress reduction region being greater than the thickness of the thinned peripheral region and the thickness of the thinned intermediate region, and the thickened stress reduction region displaces about the thinned peripheral region when subjected to a force from the thinned intermediate region; the fifth thickness is less than the fourth thickness; The golf club head of claim 1, wherein the third thickness of the thin-walled intermediate region is the thinnest portion of the striking face portion.

12. The golf club head of claim 11 , wherein the fourth thickness of the increased stress reduced region is the thickest portion of the striking face portion.

13. 13. The golf club head of claim 12, wherein the thickened stress reduction region is located a distance of 15.0 mm to 46.0 mm from the geometric center of the striking face portion, measured along a radial direction.

14. 14. The golf club head of claim 13, wherein the thickened stress reduction region is located a distance between 15 mm and 30 mm from the geometric center of the striking face portion, measured across a vertical cross section passing through the geometric center of the striking face portion.

15. 15. The golf club head of claim 14, wherein the thickened stress reduction region is located a distance between 17 mm and 28 mm from the geometric center of the striking face portion, measured across a vertical cross section passing through the geometric center of the striking face portion.

16. 16. The golf club head of claim 15, wherein the thickened stress reduction region is located a distance between 20 mm and 25 mm from the geometric center of the striking face portion, measured across a vertical cross section passing through the geometric center of the striking face portion.

17. In the golf club head, a striking face portion located on a front portion of the golf club head and adapted to strike a golf ball; a body portion attached rearwardly of the striking face portion; The hitting face portion further comprises: a substantially planar front striking surface; an interior back surface; the front striking surface and the inner rear surface in combination further include an increased thickness stress reduction region positioned proximate the periphery of the striking face portion; the thickened stress reduction region rises rearwardly from the inner rear surface of the striking face portion at both its boundary with the central region of the striking face portion and its boundary with the peripheral region of the striking face portion, thereby forming an open ring projecting rearwardly from the inner rear surface of the striking face portion, the thickness of the open ring of the thickened stress reduction region being greater than the thickness of the peripheral region of the striking face portion and the thickness of the central region of the striking face portion, and the thickened stress reduction region displaces about the peripheral region of the striking face portion when subjected to a force from the central region of the striking face portion; the thickened stress reduction region is located a distance between 15 mm and 30 mm from the geometric center of the striking face portion, measured across a vertical cross section passing through the geometric center of the striking face portion.

18. The thickened stress reduced region has a T to H ratio of between 0.6 and 1.1, the T to H ratio being defined as: T-to-H ratio = (thick stress reduced region thickness T4) / (thick stress reduced region height H4) 18. The golf club head of claim 17.

19. 19. The golf club head of claim 18, wherein the T to H ratio is between 0.7 and 0.

9.

20. 20. The golf club head of claim 19, wherein the T to H ratio is 0.8.

Images