Golf club head having slit and flexure insert

Abstract

Described herein are embodiments of golf club heads having slits and flexure inserts. The slits have openings through the club head body that communicate between the exterior of the club head and a hollow interior cavity. The flexure inserts can include a spring component and a cap. The spring component creates a spring effect within the flexure insert, increasing the internal energy of the club head upon impact, leading to improved ball speed and other golf ball performance characteristics.

Description

[Technical field]

[0001] (Cross Reference Priority) This application claims the benefit of U.S. Provisional Application No. 63 / 371,613, filed August 16, 2022, and U.S. Provisional Application No. 63 / 266,722, filed January 12, 2022, the contents of which are incorporated by reference in their entireties herein.

[0002] The present invention relates generally to golf equipment, and more particularly to golf club heads having slits and flexure inserts that increase the flexure of the striking face to manipulate club head loft, ball speed, and ball spin. [Background technology]

[0003] Many golf club heads, particularly wood-type golf club heads (i.e., drivers, fairway woods, and hybrids), have features designed to control the deflection of the striking face upon impact. Increasing the deflection of the striking face generally improves the performance of the club head, due to increased ball speed and reduced spin, both of which can lead to increased ball distance. Many prior art club heads attempt to increase the deflection of the striking face by providing an elongated slit (also referred to herein as a "slot") adjacent the striking face, the slit having an opening that passes through a portion of the club head body and into an internal cavity. The slit is then typically filled with a lightweight, flexible insert to block the opening and seal the internal cavity. The lightweight, flexible insert is typically made of a soft, viscoelastic material so as not to restrict the deflection of the slit.

[0004] Many prior art club heads focus on providing viscoelastic, homogeneous inserts of material. Due to the purely viscoelastic structure of the inserts used in the prior art slits, the aforementioned inserts absorb and dissipate energy under compression, which reduces the overall energy transfer between the club head and the golf ball. Less energy transfer between the club head and the golf ball reduces ball velocity, adversely affecting the performance of the club head.

[0005] Furthermore, the uniform material and / or uniform geometric construction of the prior art inserts provides uniform deflection throughout the slit. The prior art inserts are not designed to control deflection along various portions of the slit. The prior art inserts do not locally reinforce the high stress areas of the slit, nor do they allow maximum deflection in the low stress areas of the slit. Thus, there is a need in the art for a golf club head having a slit and insert combination configured to locally control deflection of the striking face and slit and maximize energy transfer between the club head and the golf ball. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a top perspective view of a wood-type club head with a slit and a flexure insert.

[0007] [Diagram 2] FIG. 2 is a front view of the wood-type club head of FIG.

[0008] [Diagram 3] FIG. 2 is a heel side view of the wood-type club head of FIG. 1.

[0009] [Figure 4] FIG. 2 is a sole view of the wood-type club head of FIG. 1 without the flexure insert.

[0010] [Diagram 5]FIG. 2 is a sole view of the wood-type club head of FIG. 1.

[0011] [Figure 6] FIG. 2 is a detailed cross-sectional view of a wood-type club head with a slit and a flexure insert according to the first embodiment.

[0012] [Figure 7] 7 is a detailed cross-sectional view of the wood-type club head of FIG. 6 with a slit and flexure insert according to the first embodiment.

[0013] [Figure 8] FIG. 7 is an upper internal cavity view of the slit and flexure insert of FIG. 6.

[0014] [Figure 9] FIG. 7 is a perspective internal cavity view of the slit of FIG. 6 without the flexure insert.

[0015] [Figure 10] FIG. 11 is a detailed cross-sectional view of a wood-type club head with a slit and a flexure insert according to a second embodiment.

[0016] [Figure 11] FIG. 11 is a top cross-sectional view of a spring component from the flexure insert of FIG. 10.

[0017] [Figure 12] FIG. 11 is a cross-sectional view of a wood-type club head with a slit and a flexure insert according to a third embodiment.

[0018] [Figure 13] FIG. 13 is a detailed cross-sectional view of the slit and flexure insert of FIG. 12.

[0019] [Figure 14] FIG. 13 is an upper internal view of the slit and flexure insert of FIG. 12.

[0020] [Figure 15] FIG. 13 is a detailed cross-sectional view of a wood-type club head with a slit and a flexure insert according to a fourth embodiment.

[0021] [Figure 16] FIG. 16 is a detailed cross-sectional view of the slit and flexure insert of FIG. 15.

[0022] [Figure 17] FIG. 16 is an upper internal view of the slit and flexure insert of FIG. 15.

[0023] [Figure 18] FIG. 13 is a cross-sectional view of a wood-type club head with a slit and a flexure insert according to a fifth embodiment.

[0024] [Figure 19] FIG. 13 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to a sixth embodiment.

[0025] [Figure 20] FIG. 13 is a cross-sectional view of a wood-type club head with a slit and a flexure insert according to a seventh embodiment.

[0026] [Figure 21] FIG. 13 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to an eighth embodiment.

[0027] [Figure 22] FIG. 13 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to a ninth embodiment.

[0028] [Figure 23] FIG. 17 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to a tenth embodiment.

[0029] [Figure 24]FIG. 19 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to an eleventh embodiment.

[0030] [Diagram 25] FIG. 23 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to a twelfth embodiment.

[0031] [Figure 26] FIG. 23 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to a thirteenth embodiment.

[0032] [Figure 27] FIG. 23 is a cross-sectional view of a wood-type club head having a slit and a flexure insert according to a fourteenth embodiment.

[0033] [Figure 28] FIG. 2 is a sole view of a wood-type club head having a slit extending in a heel-to-toe direction.

[0034] [Figure 29] 29 is a cross-sectional view of the golf club head of FIG. 28 with slits formed by a plurality of retaining walls according to a first embodiment.

[0035] [Diagram 30] 11 is a cross-sectional view of a golf club head with slits formed by a plurality of retaining walls according to a second embodiment. FIG.

[0036] [Diagram 31] 1 is a top perspective view of a golf club head with a slit, a flexure insert, and a striking face crown return according to one embodiment.

[0037] [Diagram 32] FIG. 32 is a cross-sectional view of the golf club head of FIG. 31 with the slit, flexure insert, and striking face crown return. Summary of the Invention

[0038] Various embodiments of a wood-type golf club head (e.g., driver, fairway wood, or hybrid) with slits and flexure inserts to strategically increase the deflection of the striking face are described herein. The club head includes a flexure insert that is tailored to provide a desired amount of deflection of the striking face. The flexure insert provides advantages over uniform prior art inserts with uniform stiffness and bending properties throughout the slit. The flexure insert can be designed with variable stiffness and bending properties to locally reinforce high stress areas of the slit and locally allow maximum deflection in low stress areas of the slit. In many embodiments, the flexure insert has a multi-material construction, where the flexure insert includes a cap and a spring component. The flexure insert always has two or more materials. The flexure insert has advantages over a slit insert with a single material. The spring component can be provided in specific areas of the slit to provide a desired stiffness profile of the flexure insert. Additionally, the spring component provides a spring effect that increases the energy transfer between the club head and the golf ball. The flexure insert allows for the stiffness and flexibility of the slit to be varied at different locations of the slit, allowing for more precise control of the deflection of the striking face. Club heads with multi-material flexure inserts offer performance advantages over prior art inserts, which are typically made of a uniform shape and material and therefore do not introduce variability in the stiffness or flexibility profile of the slit.

[0039] Additionally, embodiments of the flexure insert described herein may provide increased energy transfer between the club head and the golf ball. The spring element may be formed of a material having linear elastic properties. The spring element efficiently stores internal energy as the flexure insert compresses upon impact and releases said internal energy upon expansion. The linear elastic nature of the spring element allows it to retain and release more internal energy back to the striking surface than a prior art viscoelastic insert. A prior art pure viscoelastic insert dissipates more energy. A club head with a flexure insert having a spring element provides increased ball speed and other performance advantages over a club head having an insert made of a pure viscoelastic material.

[0040] Club heads with the slits and multi-material flexure inserts described herein can significantly improve striking face deflection and launch conditions as compared to single-material viscoelastic prior art inserts. In particular, the slits and flexure inserts with spring components can lead to increases in ball speed between 0.5 mph and 4.5 mph and increases in internal energy between 3 lb-force inches and 20 lb-force inches. Additionally, the slits and flexure inserts with spring components can provide other performance benefits such as increased striking face deflection, increased dynamic loft, and reduced ball spin rate.

[0041] The wood-type golf club heads described in this disclosure can combine the slits and flexure inserts with other club head features that improve performance. In some embodiments, the club heads can utilize a multi-material design to increase the MOI. In some embodiments, the club heads can include a large mass pad located behind the slits to provide a desirable CG location, increase ball speed and ball distance, and improve launch conditions. Any one or combination of the features described above can be combined with the slits and flexure inserts to provide a high performance club head.

[0042] DEFINITIONS The terms "first," "second," "third," "fourth," and the like, in the specification and claims, if any, are used to distinguish between similar elements and are not necessarily used to describe a particular sequential or chronological order. It is to be understood that terms used in this manner may be interchanged under appropriate circumstances, such that the embodiments described herein are capable of operating in sequences other than those illustrated or otherwise described herein. Furthermore, terms such as "include" and "have," and variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus having a set of elements is not necessarily limited to those elements and may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.

[0043] Terms such as "left," "right," "front," "rear," "top," "bottom," "above," "below," and the like, in this specification and claims, if any, are used for descriptive purposes and not necessarily to describe permanent relative positions. It is to be understood that terms so used may be interchanged under appropriate circumstances, such that embodiments of the apparatus, methods, and / or articles of manufacture described herein are operable, for example, in orientations other than those illustrated or otherwise described herein.

[0044] As used herein, the term "striking face" refers to the front of the club head that is configured to strike a golf ball. The term striking face can be used interchangeably with the term "face."

[0045] As used herein, the term "striking face perimeter" may refer to the edge of the striking face. The striking face perimeter may be located along the outer edge of the striking face where the curvature deviates from the bulge and / or roll of the striking face.

[0046] As used herein, the term "geometric center" or "geometric center" of a striking face can refer to the geometric center of the striking face's perimeter and the midpoint of the face height of the striking face. In the same or other examples, the geometric center can also be centered with respect to an engineered impact zone, which can be defined by an area of ​​grooves on the striking face. As another approach, the geometric center of the striking face can be located according to a definition of a golf governing organization, such as the United States Golf Association (USGA).

[0047] As used herein, the term "ground plane" may refer to a reference plane associated with the surface on which a golf ball rests. The ground plane may be the horizontal plane that is tangent to the sole at address position.

[0048] As used herein, the term "loft plane" may refer to a reference plane that is tangent to the geometric center point of the striking face.

[0049] As used herein, the term "loft angle" may refer to the angle measured between the loft plane and the XY plane (defined below in relation to the XYZ coordinate system).

[0050] As used herein, the term "face height" may refer to the distance measured parallel to the loft plane between the top of the striking face perimeter and the bottom of the striking face perimeter.

[0051] As used herein, the term "lie angle" may refer to the angle between a hosel axis extending through the hosel and the ground plane. The lie angle is measured from a front view.

[0052] As used herein, the "depth" of a golf club head may be defined as the dimension from the front to the rear of the golf club head.

[0053] As used herein, the "height" of a golf club head may be defined as the dimension from the crown to the sole of the golf club head. In many embodiments, the height of the club head may be measured according to a golf governing organization, such as the United States Golf Association (USGA).

[0054] As used herein, the "length" of a golf club head may be defined as the heel-to-toe dimension of the golf club head. In many embodiments, the length of the club head may be measured according to a golf governing organization, such as the United States Golf Association (USGA).

[0055] As used herein, the "face height" of a golf club head may be defined as the height measured parallel to the loft plane between the upper end of the striking face perimeter near the crown and the lower end of the striking face perimeter near the sole.

[0056] The "geometric center height" of a fairway-type golf club head as described herein is the height measured perpendicularly from the ground plane to the geometric center point of the golf club head.

[0057] The "leading edge" of the club head described herein may be identified as the sole-most portion of the periphery of the striking face.

[0058] As illustrated in Figures 2 and 3, the "XYZ" coordinate system of the golf club head 100 described herein is based on the geometric center 120 of the striking face 102. The dimensions of the golf club head 100 described herein may be measured based on the coordinate system as defined below. The geometric center 120 of the striking face 102 defines a coordinate system having an origin located at the geometric center 120 of the striking face 102. The coordinate system defines an X-axis 3040, a Y-axis 3050, and a Z-axis 3060. The X-axis 3040 extends through the geometric center 120 of the striking face 102 in a direction from the heel 104 to the toe 106 of the club head 100. The Y-axis 3050 extends through the geometric center 120 of the striking face 102 in a direction from the crown 110 to the sole 112 of the golf club head 100. The Y-axis 3050 is perpendicular to the X-axis 3040. The Z-axis 3060 extends through the geometric center 120 of the striking face 102 in a direction from the front end 108 toward the back end 111 of the golf club head 100. The Z-axis 3060 is perpendicular to both the X-axis 3040 and the Y-axis 3050.

[0059] The term or phrase "center of gravity location" or "CG location" may refer to the location of the club head center of gravity (CG) 199 relative to an XYZ coordinate system, with the CG location being characterized by location along the X-axis 3040, the Y-axis 3050, and the Z-axis 3060. The term "CGx" may refer to the CG location along the X-axis 3050, measured from the origin 120. The term "CG height" may refer to the CG location along the Y-axis 3050, measured from the origin 120. The term "CGy" may be synonymous with CG height. The term "CG depth" may refer to the CG location along the Z-axis 3060, measured from the origin 120. The term "CGz" may be synonymous with CG depth.

[0060] The XYZ coordinate system of the golf club head described herein defines an XY plane extending through the X-axis 3040 and the Y-axis 3050. The coordinate system defines an XZ plane extending through the X-axis 1040 and the Z-axis 3060. The coordinate system further defines a YZ plane extending through the Y-axis 3050 and the Z-axis 3060. The XY, XZ, and YZ planes are all perpendicular to one another and intersect at the coordinate system origin located at the geometric center 120 of the striking face 102. In these or other embodiments, the golf club head 100 can be viewed from the front when the striking face 102 is viewed from a direction perpendicular to the XY plane. Additionally, in these or other embodiments, the golf club head 100 can be viewed from the side or side cross section when the heel 104 is viewed from a direction perpendicular to the YZ plane.

[0061] As shown in Figures 2 and 3, the golf club head 100 further has a coordinate system centered at the center of gravity 199. The coordinate system has an X'-axis 3070, a Y'-axis 3080, and a Z'-axis 3090. The X'-axis 3070 extends in a heel-to-toe direction. The X'-axis 3070 is positive toward the heel 104 and negative toward the toe 106. The Y'-axis 3080 extends in a sole-to-crown direction and is perpendicular to both the Z'-axis 3090 and the X'-axis 3070. The Y'-axis 3080 is positive toward the crown 110 and negative toward the sole 112. The Z'-axis 3090 extends in a front-to-rear direction, is parallel to the ground plane, and is perpendicular to both the X'-axis 3070 and the Y'-axis 3080. The Z'-axis 3090 is positive toward the striking face 102 and negative toward the rear 111.

[0062] The term or phrase "Moment of Inertia" (hereinafter "MOI") may refer to values ​​measured on the CG 199. The term "MOIxx" may refer to the MOI measured in a heel-to-toe direction about the X'-axis 3070. The term "MOIyy" may refer to the MOI measured in a sole-to-crown direction about the Y'-axis 3080. The term "MOIzz" may refer to the MOI measured in a front-to-back direction about the Z'-axis 3090. The MOI values ​​MOIxx, MOIyy, and MOIzz determine how forgiving the club head 100 is for off-center impacts with a golf ball.

[0063] A "driver" or "driver-type" club head, as used herein, has a loft angle of less than about 16 degrees, less than about 15 degrees, less than about 14 degrees, less than about 13 degrees, less than about 12 degrees, less than about 11 degrees, or less than about 10 degrees. Additionally, in many embodiments, a "driver golf club head," as used herein, has a volume of greater than about 400cc, greater than about 425cc, greater than about 445cc, greater than about 450cc, greater than about 455cc, greater than about 460cc, greater than about 475cc, greater than about 500cc, greater than about 525cc, greater than about 550cc, greater than about 575cc, greater than about 600cc, greater than about 625cc, greater than about 650cc, greater than about 675cc, or greater than about 700cc. In some embodiments, the volume of the driver can be about 400cc to 600cc, 425cc to 500cc, about 500cc to 600cc, about 500cc to 650cc, about 550cc to 700cc, about 600cc to 650cc, about 600cc to 700cc, or about 600cc to 800cc.

[0064] As used herein, a "fairway wood" or "fairway wood-type" club head has a loft angle of less than about 35 degrees, less than about 34 degrees, less than about 33 degrees, less than about 32 degrees, less than about 31 degrees, or less than about 30 degrees. Additionally, in some embodiments, the loft angle of a fairway wood club head can be greater than about 12 degrees, greater than about 13 degrees, greater than about 14 degrees, greater than about 15 degrees, greater than about 16 degrees, greater than about 17 degrees, greater than about 18 degrees, greater than about 19 degrees, or greater than about 20 degrees. For example, in other embodiments, the loft angle of a fairway wood can be between 12 and 35 degrees, between 15 and 35 degrees, between 20 and 35 degrees, or between 12 and 30 degrees.

[0065] Further, a "fairway wood" or "fairway wood-type" club head as used herein may have a volume of less than about 400cc, less than about 375cc, less than about 350cc, less than about 325cc, less than about 300cc, less than about 275cc, less than about 250cc, less than about 225cc, or less than about 200cc. In some embodiments, the volume of a fairway wood may be about 100cc to 200cc, about 150cc to 250cc, about 150cc to 300cc, about 150cc to 350cc, about 150cc to 400cc, about 300cc to 400cc, about 325cc to 400cc, about 350cc to 400cc, about 250cc to 400cc, about 250cc to 350cc, or about 275cc to 375cc.

[0066] As used herein, a "hybrid" or "hybrid-type" club head has a loft angle of less than about 40 degrees, less than about 39 degrees, less than about 38 degrees, less than about 37 degrees, less than about 36 degrees, less than about 35 degrees, less than about 34 degrees, less than about 33 degrees, less than about 32 degrees, less than about 31 degrees, or less than about 30 degrees. Additionally, in many embodiments, the loft angle of a hybrid can be greater than about 16 degrees, greater than about 17 degrees, greater than about 18 degrees, greater than about 19 degrees, greater than about 20 degrees, greater than about 21 degrees, greater than about 22 degrees, greater than about 23 degrees, greater than about 24 degrees, or greater than about 25 degrees.

[0067] Further, as used herein, a "hybrid" or "hybrid type" has a volume of less than about 200cc, less than about 175cc, less than about 150cc, less than about 125cc, less than about 100cc, or less than about 75cc. In some embodiments, the volume of the hybrid can be from about 100cc to about 150cc, from about 75cc to about 100cc, from about 100cc to about 125cc, or from about 75cc to about 125cc.

[0068] The golf club heads described herein can be made of metals, metal alloys, composite materials, or combinations of metals and composite materials. For example, but not limited to, the golf club heads can be made of steel, steel alloys, stainless steel alloys, nickel, nickel alloys, cobalt, cobalt alloys, titanium alloys, amorphous metal alloys, or other similar materials. As a further example, but not limited to, the golf club heads can be made of C300 steel, C350 steel, 17-4 stainless steel, or T9s+ titanium.

[0069] Other features and aspects will become apparent from consideration of the following detailed description and the accompanying drawings. Before any embodiment of the present disclosure is described in detail, it should be understood that the disclosure is not limited in its application to the details or to the arrangement of the embodiments and components set forth in the following description or illustrated in the drawings. The present disclosure is capable of supporting other embodiments and can be practiced or carried out in various ways. It should be understood that the description of a particular embodiment is not intended to limit the disclosure from covering all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure. It should also be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070] I. Overview of Golf Club Head Referring to the drawings, in which like reference numerals are used in the various views to identify similar or identical components, FIGS. 1-3 generally illustrate a wood-type golf club head 100 in various views. Specifically, FIG. 1 illustrates a front perspective view of the wood-type club head 100. It should be noted that although the features described herein are illustrated in a fairway wood, any features including slits and flexure inserts may be applied to a driver or hybrid-type club head. The club head 100 may include a striking face 102 and a body 101 secured together to define a substantially closed / hollow interior cavity 107. The club head 100 includes a crown 110, a sole 112 opposite the crown 110, a heel 104, a toe 106 opposite the heel 104, a front portion 108, and a rear portion 111 opposite the front portion 108. The body 101 may further include an adjacent skirt 114 located between the crown 110 and the sole 112 , the skirt 114 extending from adjacent the heel 104 to adjacent the toe 106 of the club head 100 .

[0071] The striking face 102 and the body 101 may define an interior cavity 107 (shown in further figures below) of the club head 100. The body 101 may extend around the perimeter of the crown 110, the sole 112, the heel 104, the toe 106, the rear 111, and the front 108. In these embodiments, the striking face 102 may be located only at the front 108 of the club head 100. In other embodiments, the striking face 102 may extend around the perimeter of the front 108 and form a forward portion of at least one of the crown 110, the sole 112, the heel 104, and the toe 106. In such embodiments, the club head 100 may resemble a "cup face" or "face wrap" design. The striking face 102 includes a striking face 113 configured to impact a golf ball and a back face (shown in a later embodiment) opposite the striking face 113.

[0072] As shown in Figures 1-3, the club head 100 includes a hosel structure 105. The hosel structure 105 can receive a golf shaft (not shown). In many embodiments, the hosel structure 105 can further include a hosel sleeve 116, which can be coupled to an end of the golf shaft. In such embodiments, the hosel sleeve 116 can be coupled to the hosel structure 105 in multiple configurations, thereby allowing the golf shaft to be secured to the hosel structure 105 at multiple angles. In such embodiments, the hosel sleeve 116 can provide loft and / or lie angle adjustability for the club head 100.

[0073] In many embodiments, the club head 100 can have a multi-material design. The striking face 102 can be formed from a metallic material, and the body 101 can be formed from one or more metallic or non-metallic materials. In such embodiments, the body 101 can have a metallic first component 118 and a non-metallic second component 119. As shown in FIG. 1, the club head 100 can be configured with a wrap-around non-metallic design, with the second component 119 forming a portion of the crown 110, skirt 114, heel 104, toe 106, and sole 112. In other embodiments, the club head 100 can have any other multi-material design, with the non-metallic second component 119 forming any portion of the striking face 102, crown 112, skirt 114, heel 104, toe 106, and / or sole 112. By providing the club head 100 in a multi-material design, discretionary mass can be increased, which can be redistributed throughout the club head 100 to improve mass properties such as the MOI or CG 199 location. In other embodiments, the club head 100 can have a single-material design in which the body 101 is all formed of the same or similar material.

[0074] II. General Description of Slits 4 and 5, the club head 100 includes a slit 130 configured to receive a flexure insert 150. The slit 130 may be a through slit 130 that communicates between the exterior of the club head 100 and the interior cavity 107. In many embodiments, the slit 130 is located in the sole 112, but in other embodiments, the club head 100 may include one or more slits in the sole 112, the heel 104, the toe 106, the skirt 114, the crown 110, or any combination thereof. With reference to the illustrated embodiment of FIG. 4, the slit 130 may be an opening in the sole 112 that extends across a portion of the sole 112 in a heel-to-toe direction. The slit 130 provides strategic weakness to the sole 112, making the sole 112 more flexible than a sole without the slit 130. Thus, the slit 130 facilitates flexure of the club head body 101. The slit 130 may have a forward edge 132 adjacent the striking face 102 and a rearward edge 134 opposite the forward edge 132, with the forward edge 132 and the rearward edge 134 defining boundaries of the slit 130. The slit 130 further has a heel end 129 and a toe end 131 opposite the heel end 129. The forward edge 132 and the rearward edge 134 may extend between the heel end 129 and the toe end 131.

[0075] In many embodiments, the slits 130 may be located proximate the striking face 112 and may be spaced from the leading edge 103 by the forward sole portion 117. By being proximate to the striking face 112, the slits 130 may increase the deflection of the striking face 102 upon impact. Additionally, the proximity of the slits 130 to the striking face 102 may increase dynamic loft and / or decrease spin. Details regarding the location, shape, and configuration of the slits 130 are discussed further below.

[0076] Described herein are various embodiments of golf club heads including slits 130 for improving bending of the striking face 120. The sole 112 defines a slit 130. The slit 130 is configured to hold a flexure insert 150. Although the dimensions, properties, and characteristics of the slit 130 are described in relation to the club head 100, any of the slits 130, 230, 330, 430, 530, 630, 730, 930, 1030, 1130, 1230, 1330, 1430, 1530, 1630, 1730, 1830 described herein may be combined with any of the club head embodiments described herein. For example, any of the flexure inserts 150, 250, 350, 450, 550, 650, 750, 950, 1050, 1150, 1250, 1350, 1450, 1550, 1650, 1750, 1850 described in the following embodiments can be applied to any of the slit shapes described herein. Any of the flexure insert embodiments described above can be applied to a basic slit 130, where the slit 130 does not have a retaining wall or a complex shape. In other embodiments, any of the flexure inserts described above can be applied to a slit 130 that includes one or more retaining walls or other features described and illustrated in the following embodiments. In some embodiments, one or more retaining walls or other slit 130 shapes can complement the flexure insert 150 by further controlling the deflection of the striking face 152 or by helping to retain the flexure insert 150 within the slit 130.

[0077] As discussed above and illustrated in FIGS. 4 and 5, the sole 112 of the club head 100 defines a slit 130. The slit 130 may be a through slit 130 such that the slit 130 provides an opening between the exterior of the club head 100 and the interior cavity 107. In many embodiments, the slit 130 is located proximate the striking face 102. The slit 130 includes a forward edge 132 adjacent the striking face 102 and a rear edge 134 opposite the forward edge 132. In many embodiments, the slit 130 is located in a forward portion of the sole 112, closer to the front end 108 than the rear portion 111. With reference to FIG. 4, the slit 130 may be spaced from the leading edge 103 of the striking face 102 by the forward sole portion 117. The slit 130 extends in a heel-to-toe direction across the sole 112.

[0078] The slits 130 strategically weaken the sole 112 adjacent the striking face 102, allowing the striking face 102 to flex upon impact. Thus, the slits 130 improve the bending dynamics of the striking face 102, providing beneficial golf ball performance characteristics such as increased speed, higher launch, and lower spin. As described in more detail below, the sole 112 can define various slit 130 embodiments to improve the flexure of the striking face 102.

[0079] The shape and dimensions of the slits 130 are important in determining the nature of the deflection of the striking face 102 upon impact. As shown in Figure 4, the size, shape, and location of the slits 130 when viewed from the sole can be defined as the "profile" of the slits 130. The profile of the slits 130 affects not only the overall amount of deflection of the striking face 102, but also how individual portions of the striking face 102 deflect relative to one another (i.e., whether the striking face 102 deflects more near the geometric center 120 than near the periphery of the striking face 102).

[0080] 28, the slit profile can be characterized by a slit offset distance 141 measured from the leading edge 103 of the club head 100 to the slit front edge 132. The slit offset distance 141 is measured from the club head leading edge 103 to the slit front edge 132. In many embodiments, the slit offset distance 141 can be less than 20 mm. In some embodiments, the slit offset distance 141 can be less than 15 mm, less than 10 mm, or less than 5 mm. In some embodiments, the slit offset distance 141 can be approximately 20 mm, 15 mm, 14 mm, 13 mm, 12 mm, 11 mm, 10 mm, 9 mm, 8 mm, 7 mm, 6 mm, or 5 mm.

[0081] The profile of the slit 130 can be further characterized by a slit width and a slit length. The slit width can be measured as the lateral width between the front edge and the rear edge. In many embodiments, the slit width can range from 3.5 mm to 10 mm. In some embodiments, the slit width can be about 3.5 mm, 3.8 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, or 10 mm. The slit length can be measured as the distance between the heel-most point of the slit 130 to the toe-most point of the slit 130 measured parallel to the X-axis 1040. In many embodiments, the slit length can range from 70 mm to 90 mm. In some embodiments, the slit length can be about 70 mm, 75 mm, 80 mm, 85 mm, or 90 mm.

[0082] The profile of the slit 130 may be further characterized by the shape of the slit 130. The slit 130 may be an elongated slit 130 that extends across the sole 112 in a heel-to-toe direction. Figure 28 illustrates an embodiment of an elongated slit 130. The slit 130 may have a heel end 219 and a toe end 131. The heel end 129 and the toe end 131 may have rounded ends.

[0083] In some embodiments, the heel end 129 and the toe end 131 of the slit 130 can be angled relative to the center of the slit 130. The heel end 129 and the toe end 131 of the slit 130 can be angled backward toward the rear 111 of the club head 101. The angled toe end 129 and the heel end 131 of the slit 130 increase the heel-to-toe length Ls of the slit 130. The heel end 129 and the toe end 131 of the slit 130 can extend rearward of the striking face 102. In other words, a portion of the front edge 132 of the slit 130 can be parallel to the striking face 102, while another portion of the slit front edge 132 is non-parallel. The orientation of the slit front edge 132 contributes to lengthening the slit 130, thereby increasing the deflection of the sole 112. Increasing the length Ls of the slit 130 increases the deflection of the sole 112. The angled heel end 129 and toe end 131 also help secure the flexure insert within the slit 130 .

[0084] Additionally, the angles of the heel end 129 and toe end 131 may help reduce the overall stress experienced by the slit 130. Due to the shape of the elongated slit 130, the club head 100 experiences stress buildup at the ends 129, 131 upon impact with a golf ball. Upon impact, the front edge 132 of the slit 130 deflects more rearward than the center. As the slit 130 deflects, stress builds up at the toe end 129 and heel end 131. The angles of the heel end 129 and toe end 131 allow for more mass to be placed at both ends of the slit 130 to withstand the stress buildup.

[0085] In other embodiments, the profile of the slit 130 can have other shapes and geometries to increase the flex and durability of the slit 130. For example, the heel end 129 and the toe end 131 can have a larger angle. Also, the center of the slit 130 may be angled or curved relative to the leading edge. The heel end 129 and the toe end 131 may also have a larger width or more rounded ends, resembling a dumbbell shape.

[0086] III. Flexure Insert As discussed above and illustrated in FIG. 5, the club head 100 further includes a flexure insert 150 configured to be inserted into the slit 130. The flexure insert 150 serves multiple functions. The flexure insert 150 fills the opening formed by the slit 130 to seal the interior cavity 107. The flexure insert 150 also provides resistance to excessive bending of the slit 130 upon impact. The amount that the slit 130 bends upon impact may be related to the stiffness of the flexure insert 150. The stiffer the flexure insert 150, the less the slit 130 will bend upon impact. The flexure insert 150 may be designed to provide the maximum amount of bending of the slit 130 possible without risking excessive bending to the point of failure. The flexure insert 150 may improve the durability of the slit 130 such that the walls surrounding the slit 130 may be thin. The flexure insert 150 may also allow the striking face to be thin. In some embodiments, the flexure insert 150 may have variable stiffness at different points along the slit 130. In such embodiments, the flexure insert 150 may provide more precise control over the deflection of the striking face 102.

[0087] The flexure insert 150 can have various configurations to adjust the overall stiffness of the slit 130 to achieve the desired flexure and support of the slit 130. In some embodiments, the flexure insert 150 can be stiffer near the center of the slit 130 than near the heel end 129 or toe end 131. In other embodiments, the flexure insert 150 can be stiffer near the heel end 129 or toe end 131, if desired. Additionally, the degree of stiffness of the flexure insert 150 can also be adjusted to provide the desired flexure and support of the slit 130. In this manner, the flexure insert 150 can be customized or specially designed to adjust the overall performance of the slit 130 to achieve the desired flexure and support by making certain areas of the slit 130 stiffer or by adjusting the stiffness of the flexure insert 150 itself.

[0088] The stiffness of the flexure insert 150 can be tailored by using at least two materials in the flexure insert 150. The flexure inserts described herein have at least two materials. The first material can have a first stiffness value and the second material can have a second stiffness value that is different than the first stiffness value. The first and second materials can be arranged in any configuration to provide a desired stiffness profile for the slit, as described above.

[0089] In many embodiments, as shown and described below, the flexure insert 150 can include a spring element 160 and a cap 180. The flexure insert 150 is a separate component formed of a different material than the striking face 102 and the body 101. The flexure insert 150 is not integral with the club head 100 (i.e., it is not formed from the same material as the sole 112). The spring element 160 acts like a brace or support structure that prevents the slit 130 from flexing too much that it may break. The spring element 160 can also help increase the internal energy of the club head 100 upon impact with a golf ball. The spring element 160 stores energy when compressed upon impact and returns energy when expanded, thereby increasing the overall performance of the slit 130. The spring element 160 is an improvement over previously used inserts by returning more energy to the club head. The spring element functions linearly elastically, whereas previously used inserts (polymer and similar inserts) function viscoelastically. Viscoelastic compression results in energy loss compared to linear elastic compression. Viscoelastic compression results in significant energy loss because it absorbs and dissipates energy so that it is not returned to the system. The spring element 160 can have a plastic, composite, spring steel, titanium, or other material that provides sufficient linear elastic compression. Linear elastic compression returns most, if not all, of the energy to the system and the club head, resulting in an increase in energy. The cap 180 seals the internal cavity 107 of the club head 100. The cap 180 can be formed from a polymeric material. The cap 180 fills the remaining space of the slit 130 and blocks communication between the exterior of the club head 100 and the internal cavity 107.

[0090] During impact with a golf ball, the slits 130 allow the club head body 101 to flex more than a club head sole without the slits 130. However, if the slits 130 flex too much, the excessive flexing of the slits 130 can lead to cracking and failure. To prevent excessive flexing, the flexure insert 150 supports and reinforces the slits 130 as the sole 112 flexes upon impact with a golf ball. The flexure insert 150 prevents the sole 112 from flexing too much upon impact with a golf ball, thereby improving the durability of the club head. The increased durability of the club head allows the club head 100 to achieve the desired flexing of the striking face 102 to increase ball speed, spin, and / or distance. In some embodiments, the flexure insert 150 can reduce the need for a sole wall constructed around the slits 130. The additional wall construction adds unnecessary weight to the forward portion of the sole, which can negatively affect the MOI characteristics and CG location. Additionally, thinning the sole wall immediately surrounding the slits allows for increased flexure and ball speed while also providing increased discretionary mass. The slits 130 and flexure inserts 150 of the present invention provide for maximum flexure of the striking face 102 and sole 112 while improving golf ball performance (e.g., ball speed, spin, and distance).

[0091] The flexure insert 150 with spring element 160 provides performance advantages over conventional inserts without spring elements. Conventional inserts are made of a homogenous viscoelastic material that dissipates energy upon impact rather than returning the energy to the striking face 102. In comparison, the flexure insert 150 includes a linear elastic spring element 160 that efficiently stores and returns internal energy upon impact, increasing ball velocity and the overall internal energy of the club head.

[0092] In many embodiments, the flexure insert 150 with the spring element 160 can increase the internal energy at impact by between 3 lbf·in and 25 lbf·in over a club head with an insert without a spring element. In many embodiments, the increase in internal energy at impact can be between 3 lbf·in and 5 lbf·in, between 5 lbf·in and 10 lbf·in, between 10 lbf·in and 15 lbf·in, between 15 lbf·in and 20 lbf·in, or between 20 lbf·in and 25 lbf·in. In many embodiments, the increase in internal energy upon impact can be about 3 lb-in, about 4 lb-in, about 5 lb-in, about 6 lb-in, about 7 lb-in, about 8 lb-in, about 9 lb-in, about 10 lb-in, about 11 lb-in, about 12 lb-in, about 13 lb-in, about 14 lb-in, about 15 lb-in, about 16 lb-in, about 17 lb-in, about 18 lb-in, about 19 lb-in, about 20 lb-in, about 21 lb-in, about 22 lb-in, about 23 lb-in, about 24 lb-in, or about 25 lb-in.

[0093] Similarly, in many embodiments, a flexure insert 150 with a spring element 160 can increase ball speed (measured at a club head speed of 100 mph) at impact by between 0.5 mph and 4.5 mph over a club head with an insert that does not include a spring element. In many embodiments, the increase in ball speed at impact can be between 0.5 mph and 1.0 mph, between 1.0 mph and 1.5 mph, between 1.5 mph and 2.0 mph, between 2.0 mph and 2.5 mph, between 2.5 mph and 3.0 mph, between 3.0 mph and 3.5 mph, between 3.5 mph and 4.0 mph, or between 4.0 mph and 4.5 mph. In some embodiments, the increase in ball velocity at impact is about 0.5 mph, about 0.6 mph, about 0.7 mph, about 0.8 mph, about 0.9 mph, about 1.0 mph, about 1.1 mph, about 1.2 mph, about 1.3 mph, about 1.4 mph, about 1.5 mph, about 1.6 mph, about 1.7 mph, about 1.8 mph, about 1.9 mph, about 2.0 mph, about 2.1 mph, about 2.2 mph, about 2.3 mph, about It can be 2.4 mph, about 2.5 mph, about 2.6 mph, about 2.7 mph, about 2.8 mph, about 2.9 mph, about 3.0 mph, about 3.1 mph, about 3.2 mph, about 3.3 mph, about 3.4 mph, about 3.5 mph, about 3.6 mph, about 3.7 mph, about 3.8 mph, about 3.9 mph, about 4.0 mph, about 4.1 mph, about 4.2 mph, about 4.3 mph, about 4.4 mph, or about 4.5 mph.

[0094] IV. Overview of Multi-Material Flexure Inserts As described in more detail below, the club head 100 includes a flexure insert 150 configured to be inserted into the slit 130. In one embodiment, the flexure insert 150 may include a spring element 160 and a cap 180. The spring element 160 is configured to limit the deflection of the slit 130 upon impact with a golf ball while increasing the internal energy of the club head 100. The cap 180 is configured to seal the internal cavity 107 of the club head 100. The spring element 160 may be formed from a polymer, plastic, composite, spring steel, or titanium. The cap 180 may be formed from a polymer or plastic material.

[0095] In many embodiments, the spring element 160 is located in the center of the slit 130. In other embodiments, the spring element 160 can be located near the heel end 129 of the slit 130, near the center of the slit 130, near the toe end 131 of the slit 130, or any combination thereof. In general, the center of the sole 112 closer to the striking face 102 will deflect more compared to the portions of the sole 112 closer to the heel 104 or toe 106. In many embodiments, the spring element 160 is located near the center of the slit 130 where the sole 112 will deflect the most.

[0096] The flexure insert 150 may include one spring component 160. In other embodiments, the flexure insert may include one, two, or three spring components 160. For embodiments with two spring components (not shown), a first spring component may be located near the center of the slit 130 and a second spring component may be located near the heel end 129 or toe end 131 of the slit 130. For embodiments with three spring components, a first spring component may be located in a central portion of the slit 130, a second spring component may be located near the heel end 129 of the slit 130, and a third spring component may be located near the toe end 131 of the slit 130.

[0097] Similar to a spring, the spring element 160 stores energy upon linear elastic compression. The spring element 160 of the flexure insert 150 undergoes compression upon impact with a golf ball. Upon impact, the front edge 132 of the slit 130 deflects, i.e., deforms backward, thereby compressing the flexure insert 150. The spring element 160 limits the amount of deformation or deflection of the front edge 132 of the slit 130 to prevent failure and to increase the energy returned to the slit 130 during decompression. In other words, the spring element 160 limits the deflection of the slit 130, but pushes or springs the slit 130 back to its original shape, improving performance and durability. This provides greater structural integrity and increased internal energy than a viscoelastic polymer insert.

[0098] The spring element 160 has a first material, which may be selected from the group consisting of plastic, a composite thermoset, steel, stainless steel, spring steel, titanium, and aluminum.

[0099] The spring element 160 further has a first elastic modulus value. In some embodiments, the first elastic modulus value can be in a range of about 20 to 210 GPa. For example, the first elastic modulus value can be in a range of about 20 to 70 GPa, 70 to 120 GPa, 120 to 170 GPa, or 170 to 210 GPa.

[0100] As mentioned above, the flexure insert 150 includes a cap 180 configured to seal the club head interior cavity 157. The cap 180 may extend entirely across the profile of the slit 160 from the heel end 129 to the toe end 131 and from the forward edge 132 to the rearward edge 134. The cap 180 closes the slit 130 and separates the interior cavity 107 from the exterior of the club head 100. The cap 180 may have an outer cap surface 188 that forms part of the sole 112 at the slit 130. The cap 180 may provide structural support to the slit 130 to help prevent water and debris from entering the hollow interior cavity 107 and to prevent the slit 130 from flexing excessively.

[0101] As described above, the flexure insert 150 includes the cap 180 in addition to the spring element 160. The cap 180 has a second material, which may be an injection molded polymer such as TPE, TPU, silicone, butyl rubber, metal foam, or other suitable materials or combinations thereof.

[0102] The cap 180 further has a second elastic modulus value. In some embodiments, the second elastic modulus value can be in a range of about 0.1 GPa to 30 GPa. For example, the second elastic modulus value can be in a range of about 0.1 to 1 GPa, 1 to 5 GPa, 5 to 10 GPa, 10 to 20 GPa, or 20 to 30 GPa. In other embodiments, the spring element can have an elastic modulus of at least 30 GPa, at least 31 GPa, at least 32 GPa, at least 33 GPa, at least 33 GPa, at least 34 GPa, at least 35 GPa, at least 40 GPa, at least 45 GPa, at least 50 GPa, at least 60 GPa, at least 70 GPa, at least 80 GPa, at least 90 GPa, or at least 100 GPa. The spring element 160 has a greater elastic modulus value than the cap 180 such that the first elastic modulus value is greater than the second elastic modulus value.

[0103] In many embodiments, and as illustrated in the embodiments of FIGS. 6-27, the spring element 160 and the cap 180 combine to form the one-piece flexure insert 150. In many embodiments, the spring element 160 can be partially embedded in the cap 180 or entirely embedded in the cap 180. In many embodiments, the bottom of the spring element 160 can be embedded in the cap 180. In such embodiments, the cap 180 covers the entire bottom of the spring element 160 such that no portion of the spring element 160 is exposed to the exterior of the club head 100. In other embodiments, the bottom of the spring element 160 may not be completely embedded in the cap 180 such that at least a portion of the spring element 160 is exposed to the exterior of the club head 100. In many embodiments, only the bottom portion of the spring element 160 can be embedded in the cap 180 while the top of the spring element 160 is exposed to the hollow interior cavity 107. In many embodiments, described in more detail below, the spring element 160 can be embedded within the full cap 180 such that no portion of the spring element 160 is exposed to either the exterior of the club head 100 or the hollow interior cavity 107.

[0104] As discussed above, the flexure insert 150 provides multiple benefits. The flexure insert 150 seals the internal cavity 107, reinforces the slit 130, and prevents excessive flexure of the slit 130. Specifically, the multi-material flexure insert 150, including the spring element 160 and the cap 180, can provide performance advantages over conventional inserts. The spring element 160 creates a spring effect that increases the internal energy transferred between the club head 100 and the golf ball, improving golf ball performance (i.e., ball speed, spin, and distance).

[0105] a Flexure insert with U-shaped spring part 6-9 show one embodiment of a golf club head including a slit 130 and a flexure insert 150 that includes a U-shaped spring component 160. The U-shaped spring component includes a front wall 162, a rear wall 164, and a top wall 166. The top wall 166 connects the front wall 162 and the rear wall 164. The top wall 166 curves and extends into the interior of the club head to provide the appearance of a U-shape.

[0106] The front wall 162 and the rear wall 164 are configured to contact the front and rear surfaces of the slit 130, respectively. In other embodiments, the front wall 162 and the rear wall 164 may be offset from the front and rear surfaces of the slit. The front wall 162 and the rear wall 164 of the spring part 160 include a front protrusion 167 and a rear protrusion 168 extending forward and rearward, respectively. The front and rear protrusions 167, 168 are configured to be received in the front recess 140 and the rear recess 142, respectively. The protrusions 167, 168 allow the spring part 160 to be fixed in the slit 130. In other embodiments, the spring part 160 may have any number of other protrusions. For example, the spring part 160 may have no protrusions, the spring part 160 may have one protrusion, or the spring part 160 may have three or more protrusions.

[0107] 8, the spring element 160 is positioned within a central portion 190 of the slit 130 such that the heel and toe portions are free of the spring element 160. As discussed above, the spring element 160 targets the central portion 190 of the slit 130 because this is the portion that will deflect the most upon impact with a golf ball.

[0108] Upon impact with a golf ball, the front surface of slit 130 flexes rearward, pushing front wall 162 of spring element 160 rearward toward rear wall 164. The top wall 166 of spring element 160 flexes due to its curved shape, loading spring element 160 and storing internal energy. Once spring element 160 reaches maximum compression and bending, front wall 162 moves quickly forward, returning the front surface of slit 130 to its pre-impact position.

[0109] The spring part 160 has a length L which is the distance from the heel-most point of the spring part 160 to the toe-most point of the spring part 160. sc In this embodiment, the spring part length L sc is about 0.20 inches. In another embodiment, the spring component length L sc The spring component length L may range from about 0.10 inches to 1.50 inches. sc is the total slit length L s In the illustrated embodiment, the spring component length L sc is the total slit length L s In another embodiment, the spring component length L sc is the total slit length L s may range from about 10% to 50%.

[0110] The flexure insert 150 further comprises a cap 180. In this embodiment, the cap 180 covers the entire slit 130 and covers the spring element 160 such that the spring element 160 is not visible from the outside of the club head. The spring element 160 is partially embedded in the cap 180 such that a portion of the spring element 160 is visible from the inside of the club head. The cap 180 has a heel portion 182, a center portion 184, and a toe portion 186. The cap 180 has a thickness t measured from an outer surface 187 of the cap 180 to an inner surface 188 of the cap 180. c In many embodiments, the cap 180 may further have a thickness t c may be greater in the heel and toe portions than in the central portion.

[0111] The flexure insert 150 improves the durability of the slit by stiffening the center portion of the slit. Additionally, the U-shaped spring element 160 stores energy as the slit flexes. After maximum flexure occurs, the U-shaped spring element 160 returns energy to the club head, increasing ball speed, spin, and distance. The U-shaped spring element 160 also prevents failure of the slit by preventing it from flexing enough to crack.

[0112] In this embodiment, the spring element 160 has a U-shaped configuration. In other embodiments, the spring element 160 can have other shaped configurations, such as a V-shaped or W-shaped configuration. In each of these embodiments, a portion of the spring element extends toward the interior of the cavity such that a portion of the spring element is not embedded within the cap and is visible from the inside of the club head. In each of these embodiments, the spring element 160 contacts both the front and rear walls of the slit.

[0113] The shape of the slit 130 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 130 can be adjusted as desired. Additionally, the shape of the flexure insert 150 may also be adjusted such that the flexure insert 150 is complementary to the walls of the slit 130.

[0114] b. Flexure insert with floating spring element 10 and 11 show a second embodiment of a club head including a slit 230 and a flexure insert 250. The flexure insert 250 includes a spring element 260. In this embodiment, the spring element 260 is fully embedded in the cap 280. In other words, the spring element can float in the cap 280. In the embodiment of FIGS. 10 to 12, the spring element 260 can be spaced from the edge of the slit 230 such that the spring element 260 does not contact the front surface 233 or the rear surface 235 of the slit 230. In this embodiment, the spring element 260 is not connected to the walls of the slit 230. The spring element 260 acts like a "floating spring" in that the spring element 260 floats in the cap 280 and does not contact the walls of the slit 230. As mentioned above, the spring element 260 can be located anywhere in the cap 280.

[0115] As shown in FIGS. 10 and 11, the spring element 260 may have an elliptical shape. The elliptical shape has a major axis 270 and a minor axis 272. The major axis 270 of the elliptical shape may be aligned in the heel-to-toe direction within the slit 230, while the minor axis 272 of the elliptical shape may be aligned in the front-to-back direction. In this manner, the elliptical spring element 260 may be longer in the heel-to-toe direction than in the front-to-back direction. Additionally, as shown in FIGS. 10 and 11, the flexure insert 250 may include a series of elliptical spring elements 260 disposed within the slit 230. The elliptical shape allows the spring elements 260 to flex upon impact. The spring elements 260 flex along the minor axis 272 such that the minor axis distance is reduced. In other embodiments, the club head may include floating spring elements 260 that are not necessarily elliptical in shape. In alternative embodiments, the floating spring elements may have a circular, triangular, rectangular, columnar, or any other suitable shape. In each of these embodiments, the spring components do not contact the front and rear surfaces of the slit such that there is a different material between the spring components and the walls of the slit.

[0116] As shown in Figures 10 and 11, the cap 280 can completely fill the slit 230. The cap 280 can have a cap thickness tc. The cap thickness tc can be equal to the sole thickness at the front edge of the slit 230. The cap thickness tc can be equal to the sole thickness at the rear edge of the slit 230. The elliptical shaped spring element is disposed within the cap 280 such that the cap 280 completely surrounds the spring element 260.

[0117] In this embodiment, the spring element 260 has a continuous circumference. A continuous circumference allows the spring element 260 to bend and return to its original shape. The spring element can be of any desired shape, which has a continuous circumference. If the embedded spring element had a discontinuous circumference, the spring element would not be securely attached to the walls of the slit, adversely affecting the spring element's ability to store energy and return to its original shape.

[0118] The shape of the slit 230 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 230 can be adjusted as desired. Additionally, the shape of the flexure insert 250 may also be adjusted such that the flexure insert 250 is complementary to the walls of the slit 230.

[0119] Flexure insert with N-shaped spring element 12-14 show a third embodiment of a golf club head including a slit 330 and a flexure insert 350. The flexure insert 350 includes an "N-shaped" spring element 360. The N-shaped spring element 360 includes a front arm 361, a rear arm 363, and a cross arm 365 connecting the front arm 361 and the rear arm 363. The N-shaped spring element 360 is configured to flex within the slit 330 in response to the force of impact with a golf ball while providing resistance to excessive flexure of the slit 330. The "N-shaped" spring element 360 can also be viewed as a "Z-shape", where the "Z-shape" is rotated on its side.

[0120] The forearm 361 includes an upper forearm end 371 and a lower forearm end 373 opposite the upper forearm end 371. The forearm 361 defines a spring front wall 362 that extends vertically between the upper forearm end 371 and the lower forearm end 373. The spring front wall 362 forms the forward most surface of the flexure insert 350 and is configured to engage a front surface of the slit 330.

[0121] Similarly, rear arm 363 includes a rear arm upper end 375 and a rear arm lower end 377 opposite front arm upper end 375. Rear arm 363 defines a spring rear wall extending vertically between rear arm upper end 375 and rear arm lower end 377. Spring rear wall 363 forms the rearmost surface of flexure insert 350 and is configured to engage the rear surface of slit 330.

[0122] A cross arm 365 extends between the front arm 361 and the rear arm 363. In many embodiments, the cross arm 365 extends diagonally from the front arm upper end 371 to the rear arm lower end 377. This orientation forms an "N" shape when viewed in cross section (as shown by FIGS. 12 and 13). In other embodiments (not shown), the cross arm 365 can extend diagonally in the opposite direction from the front arm lower end 373 to the rear arm upper end 375. The diagonal orientation of the cross arm 365 allows the N-shaped spring element 360 to compress during impact with a golf ball.

[0123] The N-shaped spring part 360 defines a front joint 378 located at the junction between the cross arm 365 and the front arm 361, and a rear joint 379 located at the junction between the cross arm 365 and the rear arm 363. The front joint 378 and the rear joint 379 form strategic weak points in the N-shaped spring part 360, allowing the part to compress in the fore-aft direction. The N-shaped spring part 360 further defines a front joint angle defined as the acute angle formed between the front arm 361 and the cross arm 365. Similarly, the N-shaped spring part 360 defines a rear joint angle defined as the acute angle formed between the rear arm 363 and the cross arm 365. In many embodiments, the front joint angle and the rear joint angle may be substantially similar. In other embodiments, the front joint angle and the rear joint angle may be different. In many embodiments, the front joint angle and / or the rear joint angle may be between about 25 degrees and 65 degrees. For example, the front joint angle and / or the rear joint angle may be between approximately 25 degrees and 35 degrees, between 35 degrees and 45 degrees, between 45 degrees and 55 degrees, or between 55 degrees and 65 degrees. The front joint angle and the rear joint angle are each measured when the spring component is in a "rest" position where the club head is not experiencing an impact force.

[0124] The N-shaped spring element 360 cooperates with the cap 380 to form the flexure insert 350. In some embodiments, both the front arm lower end 373 and the rear arm lower end 377 can be embedded within the cap 380 such that no portion of the N-shaped spring element 360 is exposed to the exterior of the club head. In some embodiments, the front arm upper end 371 and the front arm lower end 373 may not be embedded within the cap 380 such that the front arm upper end 371 and the front arm lower end 373 are exposed to the hollow interior cavity. In other embodiments, the N-shaped spring element 360 may be completely embedded within the cap 380 such that no portion of the N-shaped spring element 360 is exposed to either the exterior of the club head or the hollow interior cavity.

[0125] The N-shaped spring element 360 is configured to flex under the load of a golf ball impact while providing structural support to the edges and surfaces of the slit 330 to prevent excessive flexing of the slit 330. Upon impact between the club head and the golf ball, the front joint 378 and the rear joint 379 allow the N-shaped spring element 360 to compress in response to the load applied by the edges of the slit 330 to the front and rear arms 361, 363. The more the N-shaped spring element 360 compresses, the more resistance the spring element 360 applies to the edges of the slit 330. In this manner, the N-shaped spring element 360 allows the slit 330 to flex without excessive flexing.

[0126] The N-shaped spring element 360 is configured to be disposed within a central portion 390 of the slit 330 such that the heel and toe portions of the slit 330 are devoid of the spring element 360. The spring element 360 targets and reinforces the central portion 390 of the slit to prevent it from over-bending. In other embodiments, the spring element 360 may be configured to abut the heel or toe portions of the slit 330.

[0127] The shape of the slit 330 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 330 can be adjusted as desired. Additionally, the shape of the flexure insert 350 may also be adjusted such that the flexure insert 350 is complementary to the walls of the slit 330.

[0128] d. Flexure insert with hook-shaped spring element 15-17 show a fourth embodiment of a club head including a slit 430 and a flexure insert 450. In this embodiment, the flexure insert 450 includes a "hook-shaped" spring element 460. The hook-shaped spring element 460 includes a bumper 474 configured to engage a front surface 433 of the slit 430 and an anchor 463 spaced rearwardly from the bumper 474 by a shank portion 461. The hook-shaped spring element 460 is configured to flex within the slit 430 in response to the force of a golf ball impact while providing resistance to excessive flexure of the slit 430. The hook-shaped spring element 460 may be asymmetric and may have a varying thickness.

[0129] The bumper 474 is disposed at the front end of the hook-shaped spring member 460 proximate the front face 433 of the slit 430. The bumper 474 forms a bumper surface 476 configured to contact the slit front face 433 when the slit 430 flexes upon impact with a golf ball. The bumper 474 can extend from the shank portion 461 into the slit 430. In some embodiments, the bumper surface 476 can be substantially flat to fit flush against the front face 433 of the slit 430. In other embodiments, the bumper surface 476 can be curved, as shown by FIGS. 15 and 16. In some embodiments, the bumper surface 476 can be configured to contact the front face 433 of the slit 430 when the club head is in a rest position (when the club head is not experiencing any impact force). In other embodiments, a gap can be formed between the bumper surface 476 and the front face 433 of the slit 430 when the club head is in a rest position. In the embodiments having the aforementioned gap, upon impact with a golf ball, the deflection of the slit 430 closes the gap and the slit front surface 433 engages the bumper surface 476. Thus, in such embodiments, the hook-shaped spring element 460 only contacts the front surface 430 of the slit 430 upon impact with the golf ball.

[0130] The anchor 463 is located at the rear end of the hook-shaped spring element 460 and is mounted within an inner recess 470 of the sole rearward of the slit 430. As shown in FIGS. 15-17, the club head has a recess 470 in the inner surface of the sole configured to receive the anchor 463. The recess 470 can be spaced rearward from the rear edge 434 of the slit 430. The recess 470 can extend substantially parallel to the rear edge 434 of the slit 430 in a substantially heel-to-toe direction. The anchor 463 can be substantially vertical and extends into the recess 470 in a sole direction. Upon impact with a golf ball, the anchor 463 presses against a rear wall of the recess to facilitate compression of the hook-shaped spring element 460.

[0131] In many embodiments, the recess 470 can be positioned to correspond to a heel-to-toe location of a particular embodiment of the hook-shaped spring element 460. For example, in many embodiments in which the hook-shaped spring element 460 is located in a central portion of the slit 430, the recess 470 can be located in the central portion 490 of the sole rearward of the central portion 490 of the slit 430.

[0132] As described above, the bumper 474 and the anchor 463 of the hook-shaped spring element 460 are connected by the shank portion 461. The shank portion 461 can extend in a substantially fore-aft direction. The shank portion 461 can be located partially within the slit 430 and partially within the hollow internal cavity. The bumper 474 is disposed within the slit 430 and the anchor 463 is received within a recess 470 spaced rearwardly from the slit 430, so that the shank portion 461 can extend from the slit 430 through the internal cavity to the recess 470. In many embodiments, the shank portion 461 bridges a portion of the sole located between the slit rear edge 434 and the recess 470, as shown in Figures 15-17.

[0133] The hook-shaped spring element 460 is configured to flex under the load of a golf ball impact while providing structural support to the edges and surfaces of the slit 430 to prevent excessive flexing of the slit 430. The hook-shaped spring element 460 may be compressed in a forward and backward direction upon impact with a golf ball. As the slit 430 flexes, the hook-shaped spring element 460 is compressed between the slit front face and the recess rear wall exerting a rearward force on the bumper 474, forcing the bumper to move downward, bending the entire spring element 460 and exerting a forward force against the anchor. The more the hook-shaped spring is compressed, the more resistance it exerts on the edges of the slit. In this manner, the hook-shaped spring allows the slit to flex without excessive flexing.

[0134] The shape of the slit 430 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 430 can be adjusted as desired. Additionally, the shape of the flexure insert 450 may also be adjusted such that the flexure insert 450 is complementary to the walls of the slit 430.

[0135] e. Flexure insert with elongated U-shaped spring element 18 illustrates another embodiment of a golf club head including a slit 930 and a flexure insert 950. The flexure insert 950 includes a cap 980 and a spring member 960. In this embodiment, the spring member 960 is configured to contact a front face 933 and a rear face 935 of the slit 930. The front face 933 and the rear face 935 of the slit 930 extend inwardly into the interior of the club head, providing sufficient surface area for the flexure insert 950 to fit snugly against. The rear face 935 of the slit has an indentation 937 that helps secure the spring member 960 to the slit 930. The indentation 937 is located at the top end of the rear face 935.

[0136] The spring element 960 includes a front wall 962, a rear wall 964, and a top wall 966 forming an elongated U-shaped appearance. The rear wall 964 includes a protrusion 969 extending rearwardly away from the rear wall 964 at an upper end thereof. The protrusion 969 is configured to be received by the recess 937 in the rear surface 935 of the slit 930.

[0137] Upon impact with a golf ball, the front surface 933 of the slit 930 deforms forward, thereby compressing the spring element 960. The front wall 962 of the insert also deforms forward, decreasing the distance between the front wall 962 and the rear wall 964. The front wall 962 and the rear wall 964 bend around the top wall 966.

[0138] The shape of the slit 930 as shown in the figures is not meant to be limiting, but rather is illustrated as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 930 can be adjusted as desired. Additionally, the shape of the flexure insert 950 may also be adjusted such that the flexure insert 950 is complementary to the walls of the slit 930.

[0139] f. Flexures with Cross Arms FIG. 19 illustrates another embodiment of a golf club head including a slit 1030 and a flexure insert 1050. The flexure insert 1050 includes a cap 1080 and a spring member 1060. In this embodiment, the slit 1030 has a front surface 1033, a rear surface 1035, and a top surface. The spring member 1060 can be configured to contact the front surface 1033, the rear surface 1035, and the top surface of the slit 1030. The front surface 1033 and the rear surface 1035 of the slit 1030 extend inwardly into the interior of the club head to provide sufficient surface area for the flexure insert 1050 to seal against. The top surface 1037 extends in a direction from the rear surface 1035 toward the front surface 1033. The top surface 1037 includes a protrusion 1039 that extends away from the interior of the club head to help secure the spring member 1060 to the slit 1030.

[0140] The spring element 1060 may have a shape similar in many respects to the "N" shaped spring element 360 described above. The spring element 1060 includes a front arm 1062, a rear arm 1064, and a cross arm 1066 connecting the front arm 1061 and the rear arm 1063. The spring element 1060 is configured to deflect within the slit 1030 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1030. The front arm 1061, the rear arm 1063, and the cross arm 1065 are configured to connect and function similarly to those of the front arm 361, the rear arm 363, and the cross arm 365 of the "N" shaped spring element 360. The upward projection 1039 may contact both the cross arm 1065 and the rear arm 1063 of the spring element 1060. 19, the protrusion 1039 can have a shape that corresponds to the shape of the cross arm 1065 and the rear arm 1063. The top surface 1037 of the slit 1030 abuts the end of the rear arm 1063 and can be located further inside the club head than the spring element 1060.

[0141] Upon impact with a golf ball, the front surface 1033 of the slit 1030 deforms forward, thereby compressing the spring element 1060. The front arm 1062 also deforms rearward, decreasing the distance between the front arm 1062 and the cross arm 1066.

[0142] The shape of the slit 1030 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1030 can be adjusted as desired. Additionally, the shape of the flexure insert 1050 may also be adjusted such that the flexure insert 1050 is complementary to the walls of the slit 1030.

[0143] g. A flexure insert having a spring component with a concave converging wall FIG. 20 shows another embodiment of a golf club head including a slit 1130 and a flexure insert 1100. The flexure insert 1100 includes a cap 1180 and a spring member 1160. In this embodiment, the slit 1130 has a front face 1133, a rear face 1135, and a recess 1137 in the front face 1133. The recess 1137 helps to position and secure the insert in the slit 1130. The spring member 1160 can be configured to contact the front face 1133 and the rear face 1135. The front face 1133 and the rear face 1135 of the slit 1130 extend inwardly into the interior of the club head to provide sufficient surface area for the flexure insert 1100 to fit snugly. Additionally, the front face 1133 and the rear face 1135 extend inwardly into the interior of the club head in a curved manner such that the top ends of the front face 1133 and the rear face 1135 are closer together than the bottom ends. In other words, the front surface 1133 and the rear surface 1135 of the slit 1130 are concave. In other embodiments, the front surface 1133 and / or the rear surface 1135 may or may not be convexly curved.

[0144] The spring element 1160 may have a shape similar in many respects to the "U" shaped spring element 160 described above. The spring element 1160 includes a front wall 1162, a rear wall 1164, and a top wall 1166 connecting the front wall 1162 and the rear wall 1164. The spring element 1160 is configured to deflect within the slit 1130 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1130. The front wall 1162, rear wall 1164, and cross wall 1166 are configured to connect and function similarly to those of the front wall 162, rear wall 164, and top wall 166 of the "U" shaped spring element 160. The front wall 1162 of the spring element 1160 includes a protrusion 1169 configured to be received by the recess 1137.

[0145] Upon impact with a golf ball, the front surface 1133 of the slit 1130 deforms forward, thereby compressing the spring element 1160. The front wall 1162 of the insert also deforms forward, decreasing the distance between the front wall 1162 and the rear wall 1164. The front wall 1162 and the rear wall 1164 bend around the top wall 1166.

[0146] The shape of the slit 1130 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1130 can be adjusted as desired. Additionally, the shape of the flexure insert 1150 may also be adjusted such that the flexure insert 1150 is complementary to the walls of the slit 1130.

[0147] h Flexure insert with V-shaped spring element 21 shows another embodiment of a golf club head including a slit 1230 and a flexure insert 1250. The flexure insert 1250 includes a cap 1280 and a spring member 1260. In this embodiment, the slit 1230 has a front face 1233 and a rear face 1235. The spring member 1260 can be configured to contact the front face 1233 and the rear face 1235. The front face 1233 and the rear face 1235 of the slit 1230 extend inwardly into the interior of the club head to provide sufficient surface area for the flexure insert 1250 to seal against. Additionally, the front face 1233 and the rear face 1235 are curved and extend inwardly into the interior of the club head. The front face 1233 has a concave shape and the rear face 1235 has a convex shape.

[0148] The "V" shaped spring element 1160 may have a shape similar in many respects to the previously described "U" shaped spring element 160. The spring element 1260 includes a front wall 1261, a rear wall 1263, and a top wall 1265 connecting the front wall 1261 and the rear wall 1263. The spring element 1260 is configured to deflect within the slit 1230 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1230. The front wall 1262, rear wall 1264, and cross walls 1266 are configured to connect and function similarly to those of the front wall 162, rear wall 164, and top wall 166 of the "U" shaped spring element 160.

[0149] Upon impact with a golf ball, the front surface 1233 of the slit 1230 deforms forward, thereby compressing the spring element 1260. The front wall 1262 of the insert also deforms forward, decreasing the distance between the front wall 1262 and the rear wall 1264. The front wall 1262 and the rear wall 1264 bend around the top wall 1266.

[0150] The shape of the slit 1230 as shown in the figures is not intended to be limiting, but rather is illustrated as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1230 can be adjusted as desired. Additionally, the shape of the flexure insert 1250 may also be adjusted such that the flexure insert 1250 is complementary to the walls of the slit 1230.

[0151] i. A flexure insert comprising a U-shaped spring member with a curved back wall FIG. 22 illustrates another embodiment of a golf club head including a slit 1330 and a flexure insert 1350. The flexure insert 1350 includes a cap 1380 and a spring member 1360. In this embodiment, the slit 1330 has a front surface 1333 and a rear surface 1335. The spring member 1360 can be configured to contact the front surface 1333 and the rear surface 1335. The front surface 1333 and the rear surface 1335 of the slit 1330 extend inwardly into the interior of the club head, providing sufficient surface area for the flexure insert 1350 to fit against. Additionally, the front surface 1333 has a generally flat surface, and the rear surface 1335 has a curved surface. The rear surface 1335 is concave. The curvature of the rear surface 1335 helps to secure the insert 1350 in place.

[0152] The spring element 1360 may have a shape similar in many respects to the "U" shaped spring element 160 described above. The spring element 1360 includes a front wall 1360, a rear wall 1362, and a top wall 1366 connecting the front wall 1362 and the rear wall 1364. The spring element 1360 is configured to deflect within the slit 1330 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1330. The front wall 1362, rear wall 1364, and top wall 1366 are configured to connect and function similarly to those of the front wall 162, rear wall 164, and top wall 1366 of the "U" shaped spring element 160. The rear wall 1364 has a shape complementary to the curved rear surface 1335 of the slit 1330.

[0153] Upon impact with a golf ball, the front surface 1333 of the slit 1330 deforms forward, thereby compressing the spring element 1360. The front wall 1362 of the insert also deforms forward, decreasing the distance between the front wall 1362 and the rear wall 1364. The front wall 1362 and the rear wall 1364 bend around the top wall 1366.

[0154] The shape of the slit 1330 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1330 can be adjusted as desired. Additionally, the shape of the flexure insert 1350 may also be adjusted such that the flexure insert 1350 is complementary to the walls of the slit 1330.

[0155] j Flexure insert with U-shaped spring component and curved surface FIG. 23 illustrates another embodiment of a golf club head including a slit 1430 and a flexure insert 1450. The flexure insert 1450 includes a cap 1480 and a spring member 1460. In this embodiment, the slit 1430 has a front surface 1433 and a rear surface 1435. The spring member 1460 can be configured to contact the front surface 1433 and the rear surface 1435. The front surface 1433 and the rear surface 1435 of the slit 1430 extend inwardly into the interior of the club head, providing sufficient surface area for the flexure insert 1450 to fit against. Additionally, the front surface 1433 has a generally flat surface, and the rear surface 1435 has a curved surface. The rear surface 1435 is concave. The curvature of the rear surface 1435 helps to secure the insert 1450 in place.

[0156] The spring element 1460 may have a shape similar in many respects to the "U" shaped spring element 160 described above. The spring element 1460 includes a front wall 1460, a rear wall 1462, and a bottom wall 1466 connecting the front wall 1462 and the rear wall 1464. The spring element 1460 is configured to deflect within the slit 1430 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1430. The front wall 1462, rear wall 1464, and bottom wall 1466 are configured to connect and function similarly to those of the front wall 162, rear wall 164, and top wall 166 of the "U" shaped spring element 160. The rear wall 1464 has a shape complementary to the curved rear surface 1435 of the slit 1430.

[0157] Upon impact with a golf ball, the front surface 1433 of the slit 1430 deforms forward, thereby compressing the spring element 1460. The front wall 1462 of the insert also deforms forward, decreasing the distance between the front wall 1462 and the rear wall 1464. The front wall 1462 and the rear wall 1464 bend about the bottom wall 1466.

[0158] The shape of the slit 1430 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1430 can be adjusted as desired. Additionally, the shape of the flexure insert 1450 may also be adjusted such that the flexure insert 1450 is complementary to the walls of the slit 1430.

[0159] k. Flexible insert with two cross arms 24 illustrates another embodiment of a golf club head including a slit 1530 and a flexure insert 1550. The flexure insert 1550 includes a cap 1580 and a spring member 1560. The spring member 1560 can be configured to contact a front face 1533 and a rear face 1535. The front face 1533 and the rear face 1535 of the slit 1530 extend inwardly toward the interior of the club head to provide sufficient surface area for the flexure insert 1550 to seal against. Additionally, the front face 1533 and the rear face 1535 extend inwardly generally vertically toward the interior cavity of the club head such that the top ends of the front face 1533 and the rear face 1535 are approximately equal to the bottom ends of the front face 1533 and the rear face 1535.

[0160] The spring element 1560 may have a shape similar in many respects to the "N" shaped spring element 360 described above. The spring element 1560 includes a front arm 1562, a rear arm 1564, a first cross arm 1566 connecting the front arm 1562 and the rear arm 1564, and a second cross arm 1568 connecting the front arm 1562 and the rear arm 1564. The first cross arm 1566 may be closer to the interior cavity of the club head. The second cross arm 1568 may be closer to the sole of the golf club. The first cross arm 1566 and the second cross arm 1568 may be spaced apart from each other. The spring element 1560 is configured to deflect within the slit 1530 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1530. The front arm 1562, the rear arm 1564, and the cross arm 1566 are configured to connect and function similarly to the front arm 361, the rear arm 363, and the cross arm 365 of the "N" shaped spring element 360. The top surface protrusion 1539 can contact both the cross arm 1566 and the rear arm 1564 of the spring element 1560. As shown in FIG. 19, the protrusion 1539 can have a shape corresponding to the shape of the cross arm 1566 and the rear arm 1564. The top surface 1537 of the slit 1530 can contact the end of the rear arm 1564 and be located further inwardly of the club head than the spring element 1560.

[0161] Upon impact with a golf ball, the front surface 1533 of the slit 1530 deforms forward, thereby compressing the spring element 1560. The front arm 1562 of the insert also deforms forward, decreasing the distance between the front arm 1562 and the rear arm 1564. Due to the orientation and angle of the first cross arm 1566 and the second cross arm 1568, the front arm 1562 also moves slightly inward, toward the inside of the club head, as the spring element 1560 compresses.

[0162] The shape of the slit 1530 as shown is not to be construed as limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1530 can be adjusted as desired. Additionally, the shape of the flexure insert 1550 may also be adjusted such that the flexure insert 1550 is complementary to the walls of the slit 1530.

[0163] Flexure insert with Z-shaped spring element FIG. 25 illustrates another embodiment of a golf club head including a slit 1630 and a flexure insert 1650. The flexure insert 1650 includes a cap 1680 and a spring member 1660. In this embodiment, the slit 1630 includes a front wall 1631 and a rear wall 1641. The front wall 1631 includes an upper surface 1632, an inclined surface 1633, and a lower surface 1635. The rear wall 1641 includes an upper horizontal surface 1642, an upper vertical surface 1643, an inclined surface 1644, a lower horizontal surface 1645, and a lower vertical surface 1646. The surfaces of the front wall 1631 and the rear wall 1641 extend inwardly into the interior cavity of the club head to provide sufficient surfaces for the flexure insert 1650 to seal against. In other embodiments, the front wall 1631 and the rear wall 1641 can have other combinations of surfaces and shapes to improve manufacturability and durability of the slit 1630.

[0164] The spring part 1660 can have a "Z-shaped" configuration, where the spring part 1660 includes an upper arm 1662, a cross arm 1664, and a lower arm 1666. The spring part 1660 has a shape that is complementary to the surfaces of the front wall 1631 and the rear wall 1641 of the slit 1630. The "Z-shaped" configuration improves the ability of the insert 1650 to be retained within the slit 1630.

[0165] The shape of the slit 1630 as shown is not intended to be limiting, but rather is shown as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1630 can be adjusted as desired. Additionally, the shape of the flexure insert 1650 can also be adjusted such that the flexure insert 1650 is complementary to the walls of the slit 1630.

[0166] m. A flexure insert with an inverted U-shaped spring part and a protrusion 26 illustrates another embodiment of a golf club head having a slit 1730 and a flexure insert 1750. The flexure insert 1750 includes a cap 1780 and a spring member 1760. In this embodiment, the slit 1730 has a front face 1733, a rear face 1735, a first recess 1737 in the front face 1733, and a second recess 1738 in the rear face 1735. The first recess 1737 and the second recess 1738 help position and secure the flexure insert 1750 in the slit 1730. The spring member 1760 can be configured to contact the front face 1733 and the rear face 1735. The front face 1733 and the rear face 1735 of the slit 1730 extend inwardly into the interior cavity of the club head to provide sufficient surface area for the flexure insert 1750 to fit snugly against. Additionally, the front face 1733 and the rear face 1735 extend generally vertically inwardly into the interior cavity of the club head such that the upper ends of the front face 1733 and the rear face 1735 are approximately the same distance apart as the lower ends of the front face 1733 and the rear face 1735.

[0167] The spring element 1760 may have a shape similar in many respects to the "U" shaped spring element 160 described above. The spring element 1760 includes a front wall 1762, a rear wall 1764, and a top wall 1766 connecting the front wall 1762 and the rear wall 1764. The spring element 1760 is configured to deflect within the slit 1730 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1730. The front wall 1762, rear wall 1764, and top wall 1766 are configured to connect and function similarly to those of the front wall 162, rear wall 164, and top wall 166 of the "U" shaped spring element 160. In this embodiment, the top wall 1766 is disposed proximate to the interior cavity of the golf club head. The front wall 1762 of the spring element 1760 has a first protrusion 1769 and a second protrusion 1770 configured to be received by the first recess 1737 and the second recess 1738 .

[0168] Upon impact with a golf ball, the front surface 1733 of the slit 1730 deforms forward, thereby compressing the spring element 1760. The front wall 1762 of the insert also deforms forward, decreasing the distance between the front wall 1762 and the rear wall 1764. The front wall 1762 and the rear wall 1764 bend around the top wall 1766.

[0169] The shape of the slit 1730 as shown is not intended to be limiting, but rather is illustrated as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1730 can be adjusted as desired. Additionally, the shape of the flexure insert 1750 may also be adjusted such that the flexure insert 1750 is complementary to the walls of the slit 1730.

[0170] n. A long, thin U-shaped flexible spring part having a protrusion 27 illustrates another embodiment of a golf club head including a slit 1830 and a flexure insert 1850. The flexure insert 1850 includes a cap 1880 and a spring member 1860. In this embodiment, the slit 1830 has a front face 1833, a rear face 1835, and a recess 1837 in the front face 1833. The recess 1837 helps to position and secure the insert in the slit 1830. The spring member 1860 can be configured to contact the front face 1833 and the rear face 1835. The front face 1833 and the rear face 1835 of the slit 1830 extend inwardly toward the inside of the club head to provide sufficient surface area for the flexure insert 1850 to fit snugly against. Additionally, the front face 1833 and the rear face 1835 extend generally vertically inwardly toward the interior cavity of the club head such that the upper ends of the front face 1833 and the rear face 1835 are approximately the same distance apart as the lower ends of the front face 1833 and the rear face 1835.

[0171] The spring element 1860 may have a shape similar in many respects to the "U" shaped spring element 160 described above. The spring element 1860 includes a front wall 1862, a rear wall 1864, and a bottom wall 1866 connecting the front wall 1862 and the rear wall 1864. The spring element 1860 is configured to deflect within the slit 1830 in response to the force of a golf ball impact while providing resistance to excessive deflection of the slit 1830. The front wall 1862, rear wall 1864, and bottom wall 1866 are configured to connect and function similarly to those of the front wall 162, rear wall 164, and top wall 166 of the "U" shaped spring element 160. In this embodiment, the bottom wall 1866 is disposed proximate to the sole of the golf club head. The front wall 1862 of the spring element 1860 includes a first protrusion 1869 and a second protrusion 1870 configured to be received by the first recess 1837 and the second recess 1838 .

[0172] Upon impact with a golf ball, the front surface 1833 of the slit 1830 deforms forward, thereby compressing the spring member 1860. The front wall 1862 of the insert also deforms forward, decreasing the distance between the front wall 1862 and the rear wall 1864. The front wall 1862 and the rear wall 1864 bend about the bottom wall 1866.

[0173] The shape of the slit 1830 as shown is not intended to be limiting, but rather is illustrated as an exemplary embodiment. For example, the width, length, profile, and walls of the slit 1830 can be adjusted as desired. Additionally, the shape of the flexure insert 1850 may also be adjusted such that the flexure insert 1850 is complementary to the walls of the slit 1830.

[0174] V. Slit retention structure The performance of the slit 130 (i.e., the amount of deflection of the striking face 102 that the slit creates) may depend on the structure of the slit 130. The structure of the slit 130 refers to the structure surrounding the through opening formed by the slit 130 and may include the various walls of the slit 130 and features of the club head 100 adjacent to the slit 130. The structure of the slit 130 may affect how the slit 130 flexes, as well as how the flexure insert 150 is retained within the slit 130. In some cases, the structure of the slit 130 may further affect the durability of the slit 130 and help prevent breakage of the sole 112. In many embodiments, it may be desirable to minimize the complexity of the structure of the slit 130 to allow for simplified manufacturing. In many embodiments, the structure of the slit 130 may include features such as mass pads (described in more detail below) that may modify the mass properties of the club head 100 to compensate for the addition of the slit 130.

[0175] As discussed above, in many embodiments, the slit 130 can be a basic opening through the sole 112. In such embodiments, the structure of the slit 130 is not formed by a retaining wall or built-up structure around the slit 130, and the walls and surfaces of the slit 130 are formed solely by the thickness of the sole 112. In many such embodiments, the thickness of the sole 112 at the forward edge 132 of the slit 130 can be similar or equal to the thickness of the sole 112 at the rearward edge 134 of the slit 130.

[0176] In many embodiments, rather than forming a basic slit 130, the club head 100 may include a slit 130 having a structure that includes one or more retaining walls or other constructed features surrounding the slit 130. As discussed above, the structure of the slit 130 may improve the durability and flexibility characteristics of the slit 130, as well as the ability of the slit 130 to retain the flexure insert 150.

[0177] 29 illustrates a club head 500 with a slit 530 defined by a number of retaining walls 592. The retaining walls 592 are formed by the sole 112 and form edges 532, 534 of the slit 530. The retaining walls 592 may be features of the sole 512 that extend upwardly from the inner surface 521 of the sole 512 into the interior cavity 507. The retaining walls 592 are configured to hold the flexure insert 550 in place such that the flexure insert 550 fills the slit 530 against the retaining walls 592. The number of retaining walls 592 includes a forward retaining wall 592a located at the forward edge 532 of the slit 530 and a rearward retaining wall 592b located at the rearward edge 534 of the slit 530.

[0178] 29, the front retaining wall 592a may be a vertical wall such that the front wall 592a may extend substantially perpendicular to the inner surface 521 of the sole 512. The front retaining wall 592a further has a front surface 594a disposed toward the rear surface 525 and a rear surface 594b disposed toward the slit 530 and configured to abut the flexure insert 550. The front retaining wall 592a has a base 596a at the junction between the front retaining wall 592a and the sole 512 and a free upper end 597a opposite the base 596a.

[0179] Similarly, the rear retaining wall 592b can be a vertical wall extending substantially perpendicular to the inner surface 521 of the sole 512. The rear retaining wall 592b further has a front surface 594a disposed toward the slit 530 and configured to abut the flexure insert 550, and a rear surface 595b disposed toward the rear 511 of the club head 500. Similar to the front retaining wall 592a, the rear retaining wall 592b has a base 596b at the junction between the rear retaining wall 592b and the sole 512, and a free upper end 597b opposite the base 596b. In many embodiments, the front retaining wall 592a and the rear retaining wall 592b can be substantially parallel to one another. In other embodiments, one or both retaining walls 592 can be angled relative to the other.

[0180] By being located at the front edge 532 and the rear edge 534 of the slit 530, the front retaining wall 592a and the rear retaining wall 592b are spaced apart from one another in the front-to-rear direction and form an opening therethrough from the exterior of the club head 500 to the interior cavity 507. The slit 530 forms an exterior opening 538 between the front retaining wall base 596a and the rear retaining wall base 596b. The exterior opening 538 forms an entrance to the slit 530 from the exterior of the club head 500. The slit 530 further forms an interior opening 536 between the front retaining wall top end 597a and the rear retaining wall top end 597b. The interior opening 536 forms an exit of the slit 530 to the interior cavity 507.

[0181] The retaining walls 592 illustrated in FIG. 29 may provide several advantages. The surfaces that the flexure insert 550 contacts (i.e., the rear surface 595a of the forward retaining wall 592a and the front surface 594b of the rearward retaining wall 592b) provide increased surface area for the flexure insert 550 to adhere to or interlock with. The increased surface area described above may increase the ability of the slit 530 to retain the flexure insert 550. Additionally, the retaining walls 592 provide additional mass around the edges 532, 534 of the slit 530, reinforcing the slit 530 and increasing its durability. The vertical retaining walls 592 illustrated in FIG. 29 have a simple shape that is not difficult to cast. Thus, providing the retaining walls 592 does not complicate the manufacturing process.

[0182] 30 illustrates a second embodiment of a club head 600 that includes multiple retaining walls 692. Each of the retaining walls 692 (i.e., a front retaining wall 692a and a rear retaining wall 692b) can have a transition portion 693 and an upper portion 698. Each of the retaining walls 692 with the transition portion 693 creates a size difference between the outer opening 638 and the inner opening 636 of the slit 630. The size difference between the outer opening 638 and the inner opening 636 forms a mechanical stop that securely holds the flexure insert 650 within the slit 630.

[0183] 30, the front retaining wall 692a can include a front wall transition 693a that begins at a base 696a of the front retaining wall 692a and extends into the interior cavity 607. The front wall transition 693a can be angled relative to the sole inner surface 621. In many embodiments, the front surface 694a of the front wall transition 693a can be angled at an angle between 30 and 60 degrees relative to the sole inner surface 621. In some embodiments, the angle between the front surface 694a of the front wall transition 693a and the sole inner surface 621 can be between 30 and 40 degrees, between 35 and 45 degrees, between 40 and 50 degrees, between 45 and 55 degrees, or between 50 and 60 degrees. In some embodiments, the angle between the front surface 694a of the front wall transition 693a and the sole inner surface 621 can be about 30 degrees, about 35 degrees, about 40 degrees, about 45 degrees, about 50 degrees, about 55 degrees, or about 60 degrees. The angle of the front wall transition 693a provides a gradual change in shape between the sole 612 and the forward retaining wall 692a.

[0184] Additionally, the front retention wall 692a has a front wall upper portion 698a that extends from the end of the front transition portion 693a opposite the base portion 696a and further into the interior cavity 607. The front wall upper portion 698a can be substantially vertical such that the front wall upper portion 698a is approximately perpendicular to the sole inner surface 621. This gradual change in shape can improve durability by minimizing stress buildup around the perimeter of the front retention wall 692a.

[0185] Similar to the front retaining wall 692a, the rear retaining wall 692b can have a rear wall transition 693b that begins at a base 696b of the rear retaining wall 692b and extends into the interior cavity 607. The rear wall transition 693b can be angled relative to the sole inner surface 621. In many embodiments, the rear surface 695b of the rear wall transition 693b can be angled at an angle between 30 and 60 degrees relative to the sole inner surface 621. In some embodiments, the angle between the rear surface 695b of the rear wall transition 693b and the sole inner surface 621 can be between 30 and 40 degrees, between 35 and 45 degrees, between 40 and 50 degrees, between 45 and 55 degrees, or between 50 and 60 degrees. In some embodiments, the angle between the rear surface 695b of the rear wall transition 693b and the sole inner surface 621 can be about 30 degrees, about 35 degrees, about 40 degrees, about 45 degrees, about 50 degrees, about 55 degrees, or about 60 degrees. The angle of the rear wall transition 693b provides a gradual change in shape between the sole 612 and the rear retaining wall 692b. Such a gradual change in shape can improve durability by minimizing stress risers around the perimeter of the rear retaining wall 692b.

[0186] Additionally, the rear retention wall 692b has a rear wall upper portion 698b that extends from an end of the rear transition portion 698b opposite the base portion 696b further into the interior cavity 607. The rear wall upper portion 698b can be substantially vertical such that the rear wall upper portion 698b is approximately perpendicular to the sole inner surface 621. In many embodiments, the rear wall upper portion 698b can be parallel to the front wall upper portion 698a.

[0187] 30 illustrates the retaining wall 692 having a flat transition 693, in other embodiments, the transition 693 can be curved or concave (when viewed in cross section) relative to the interior cavity 607. Such a curved transition 693 can provide a more gradual transition between the sole 612 and the retaining wall 692.

[0188] As shown in FIG. 30, the front wall transition 693a and the rear wall transition 693a converge toward each other as each extends deeper into the internal cavity. The convergence transition 693 creates a variable slit width Ws. The slit 630 has an outer slit width Wse located at the outer opening 638 and an inner slit width Wsi located at the inner opening 636. In many embodiments, the outer slit width Wse is greater than the inner slit width Wsi. The variable width Ws of the slit 630 forms a mechanical stop to hold the flexure insert 650 in place. The flexure insert 650 can be shaped to complementarily fill the profile of the slit 630 formed by the retaining wall 692, flush with the rear surface 695a of the front retaining wall 692a and the front surface 694 of the rear retaining wall 692b. The variable slit width Ws allows the flexure insert 650 to be inserted through the larger exterior opening 638 but prevents it from slipping through the smaller interior opening 636 into the interior cavity 607.

[0189] As shown in FIG. 30, in some embodiments, the flexure insert 650 can further include a stopper 655 configured to secure the flexure insert 650 in the slit 630. The stopper 655 can be located at an end of the flexure insert 650 exposed to the internal cavity 607. The stopper 655 can be a portion of the flexure insert 650 that has a front-to-back width that is slightly larger than the inner slit width Wsi. When the flexure insert 650 is assembled in the slit 650, the stopper 655 can overlap the top end 697 of the retaining wall 692. The stopper provides resistance against the top end 697 of the retaining wall 692 to prevent the flexure insert 650 from exiting the slit 630 through the exterior opening 638. The flexible material of the flexure insert 650 compresses the stopper 655 as the flexure insert 650 is pressed into the slit 630. Once the stopper 655 passes through the interior opening 636, the stopper 655 may decompress and return to its original shape, securely locking the flexure insert 650 in place.

[0190] VI. Club head with slits and striking face crown return The club heads described herein may include a variety of additional features that work (directly or indirectly) with the slits to provide high performance club heads. Any of the additional features described below may be provided in combination with any of the various slits 130, 230, 330, 430, 530, 630, 730, 930, 1030, 1130, 1230, 1330, 1430, 1530, 1630, 1730, 1830 and flexure inserts 150, 250, 350, 450, 550, 650, 750, 950, 1050, 1150, 1250, 1350, 1450, 1550, 1650, 1750, 1850 described herein.

[0191] 31 and 32 show a club head 700 with a striking face 702 having a crown return 727 and an associated slit 730. As shown in FIG. 31, the striking face 702 defines a striking face portion 728 located at a front end 708 of the club head 700 and a crown return 727 extending rearwardly from a top of the striking face portion 728. The crown return 728 extends rearwardly and may form at least a forward portion of a crown 710. The striking face 702 may have an upper perimeter 737 and a lower perimeter 739, each of which functions as an interface between the striking face 702 and the body 701. For example, the upper perimeter 737 may be located along the rear edge of the crown return 727 and form an interface between the striking face 702 and the crown 710. In the embodiment of FIGS. 31 and 32, a lower perimeter 739 of the striking face is located at the front end 708 and an upper perimeter 737 of the striking face is located at the crown 715 and spaced rearwardly from the front end 708 .

[0192] In many embodiments, the crown return 727 can have a return depth Dcr measured in a front-to-rear direction from the geometric center 720 to the upper periphery 737, as shown in FIG. 32. In many embodiments, the return depth Dcr can be between 0.25 and 0.50 inches, between 0.50 and 0.75 inches, between 0.75 and 1.0 inches, between 1.0 and 1.25 inches, or between 1.25 and 1.5 inches. In many embodiments, the return depth Dcr can be greater than 0.50 inches, greater than 0.60 inches, greater than 0.70 inches, greater than 0.80 inches, greater than 0.90 inches, greater than 1.0 inches, greater than 1.1 inches, greater than 1.2 inches, greater than 1.3 inches, greater than 1.4 inches, or greater than 1.5 inches.

[0193] In many embodiments, the striking face 702 and the body 701 are formed from different materials. In many embodiments, the striking face 702 has a stronger material than the body 701. By forming a portion of the crown 710 with the crown return 727, a stronger material is provided along the transition from the leading end 708 to the crown 710. The crown return 727 thereby increases the durability of the aforementioned area that is typically at increased risk of failure upon impact.

[0194] The crown return 727 allows for stronger striking face 702 material to be placed in the forward portion of the crown 710, thereby allowing the aforementioned forward portion of the crown 710 to be thinner without sacrificing durability. Thinning this portion of the crown 710 allows for increased deflection of the striking face 702, which complements the internal energy gain provided by the slits 730 to provide maximum ball velocity increase. In many embodiments, the crown return 727 can have a thickness (measured from the outer surface to the inner surface of the crown return 727) of less than 0.040 inches. In many embodiments, the crown return 727 can have a thickness of less than 0.038 inches, less than 0.036 inches, less than 0.034 inches, less than 0.032 inches, less than 0.030 inches, less than 0.028 inches, less than 0.026 inches, less than 0.024 inches, less than 0.022 inches, or less than 0.020 inches.

[0195] Typically, the striking face 702 may be formed by stamping, pressing, or forging rather than a casting process. This makes it difficult to form the striking face 702 into a complex shape. In many embodiments of the club head 700 that include the slit 730, particularly those described above with one or more retaining walls, the shape of the slit 730 must be cast into the sole 712. In many embodiments, the proximity of the slit 730 to the front end 708 makes it disadvantageous for the striking face 702 to form any portion of the sole 712. As such, the striking face 702 may not have a sole return. In such an embodiment, the striking face 702 may form part of the crown 710 via the crown return 727, but may not form part of the sole 712.

[0196] In other embodiments (not shown), particularly those having a simple slit 730 design, the striking face 702 may have a sole return that extends rearwardly from the striking surface portion 728 along the sole 712. In such embodiments, the sole return may have one or more edges that form one or more edges of the slit 730. The striking face 702 having the crown return 727 may be provided in combination with any of the various slit shapes described herein, and in combination with any of the various flexure insert embodiments 150, 250, 350, 450, 550, 650, 750, 950, 1050, 1150, 1250, 1350, 1450, 1550, 1650, 1750, 1850 described herein.

[0197] VII. Club Head with Slits and Mass Pad In many embodiments, the club head includes an inner mass pad to provide a desired CG location that further enhances golf ball performance characteristics. Referring to FIG. 32, the club head 700 includes an inner mass pad 745 in combination with the slit 730. In many embodiments, the mass pad 745 is integrally formed from the inner sole surface 721. The mass pad 745 is a large concentration of mass having a thickness greater than the stock thickness of the sole 712. The mass pad 745 may be located between the slit 730 and the trailing end 711. However, in many embodiments, the mass pad 745 may be located closer to the striking face 702 than the trailing end 711, providing the club head 700 with a relatively forward CG 799 location to reduce undesirable golf ball spin. The mass pad 745 can be provided in combination with any of the various slit shapes described herein, any of the various flexure insert embodiments 150, 250, 350, 450, 550, 650, 750, 950, 1050, 1150, 1250, 1350, 1450, 1550, 1650, 1750, 1850 described herein, or any of the other additional features described herein.

[0198] In many embodiments, the mass pad 745 is spaced rearward from the slit 730, as shown in FIG. 32. In such embodiments, the mass pad 745 does not form any portion of the slit 730 or any portion of any retaining wall 792. In such embodiments, the mass pad 745 may be spaced from the slit 730 by a portion of the sole 712. In such embodiments, the mass pad 745 does not form the rear edge 734 of the slit 730 and is separate and independent of any retaining wall 792. Spaced apart the mass pad 745 from the slit 730 allows the slit to bend or flex a maximum amount. Because the mass pad 745 is thicker (and therefore less flexible) than the remainder of the sole 712, spacing the mass pad 745 rearward from the slit 730 allows the sole 712 and striking face 702 to flex more. Additionally, spacing the mass pad 745 rearward of the slit 730 allows the CG 799 to be located further rearward, resulting in a club head 700 with a higher MOI.

[0199] In other embodiments (not shown), it may be desirable for the mass pad 745 to be immediately adjacent the slit 730 such that the mass pad 745 forms a portion of the slit 730. In such embodiments, the mass pad 745 may form at least a portion of the slit trailing edge 734. By providing the mass pad 745 immediately adjacent the slit 730, a much more forward CG 799 location may be provided, resulting in improved launch characteristics (i.e., lower spin rate) for the golf ball.

[0200] In many embodiments, the mass pad 745 can have a mass between 25 grams and 40 grams. In some embodiments, the mass pad 745 can have a mass between 25 grams and 30 grams, between 30 grams and 35 grams, or between 35 grams and 40 grams. As noted above, in many embodiments, the mass pad 745 is integrally formed with the sole 712. In other embodiments, the mass pad 745 can be formed separately and attached to the sole 712 (either medially or laterally) via adhesive and / or mechanical attachment means.

[0201] VIII. Characteristics of Center of Gravity and Moment of Inertia The club heads described herein provide a means for improving the bending dynamics of the striking face to provide beneficial golf ball performance characteristics such as increased speed, higher launch, and lower spin. As discussed above, the slits 130 are positioned proximate to the striking face 102 to affect the bending characteristics of the striking face 102. The following mass properties are applicable to any combination of the various slits 130, 230, 330, 430, 530, 630, 730, 930, 1030, 1130, 1230, 1330, 1430, 1530, 1630, 1730, 1830 and flexure inserts 150, 250, 350, 450, 550, 650, 750, 950, 1050, 1150, 1250, 1350, 1450, 1550, 1650, 1750, 1850 described herein.

[0202] Consideration of slits often removes mass from the front of the club head, which can adversely affect center of gravity (CG) and moment of inertia (MOI) characteristics. However, the club heads described herein have improved center of gravity locations, thereby providing improved moment of inertia characteristics. Specifically, the club heads with slits described herein have low and rearward center of gravity locations, thereby providing high moment of inertia. Club heads with high moment of inertia improve forgiveness on off-center hits. Thus, various configurations of club heads with slits as described herein improve feel, increase forgiveness, and improve playability.

[0203] To achieve improved center of gravity location and high moment of inertia characteristics, the club head may further include structures that affect the mass properties of the club head, such as removable weights, mass pads, thinned crowns, weighted inserts, and / or lightweight crowns formed from non-metallic materials. These structures allow for tuning of the mass properties to achieve a low and rearward CG location as well as high moment of inertia characteristics. Described below are improved CG locations that provide a low and rearward CG location to increase the moment of inertia and forgiveness of the club head.

[0204] In various embodiments of a driver-type club head, the CGx position can range from -2mm to 6mm. In some embodiments, the driver-type club head has a CGx position between -2mm to 2mm, or 2mm to 6mm. In some embodiments, the driver-type club head has a CGx position of about -2mm, -1.5mm, -1mm, 0mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, or 6mm.

[0205] In various embodiments of the fairway wood type club head, the CGx position may range from -7mm to 1mm. In some embodiments, the fairway wood type club head has a CGx position between -7mm to -3mm, or 3mm to 1mm. In some embodiments, the fairway wood type club head has a CGx position of about -7mm, -6mm, -5mm, -4mm, -3mm, -2mm, -1mm, 0mm, 0.5mm, or 1mm.

[0206] In various embodiments of the hybrid type club head, the CGx position may be between -5mm and 2mm. In some embodiments, the hybrid type club head has a CGx position between -5mm and -1mm, or 1mm and 2mm. In some embodiments, the hybrid type club head has a CGx position between -4mm and 0mm, -3mm and 1mm, or 2mm and 2mm. In some embodiments, the hybrid type club head has a CGx position of about -5mm, -4mm, -3mm, -2.5mm, -2mm, -1.5mm, -1mm, -0.5mm, 0mm, 0.5mm, 1mm, 1.5mm, or 2mm.

[0207] In various embodiments of the driver-type club head, the CG has a CGy position in the range of -4mm to -10mm. In some embodiments, the driver-type club head has a CGy position in the range of -4mm to -7mm, or 7mm to -10mm. In some embodiments, the driver-type club head has a CGy position of about -4mm, -5mm, -6mm, -7mm, -8mm, -9mm, or 10mm.

[0208] In various embodiments of the fairway wood type club head, the CG has a CGy position in the range of -3mm to -12mm. In some embodiments, the fairway wood type club head has a CGy position in the range of -3mm to -7mm, or -7mm to -12mm. In some embodiments, the fairway wood type club head has a CGy position of about -3mm, -4mm, -5mm, -6mm, -7mm, -8mm, -9mm, -10mm, -11mm, or 12mm.

[0209] In various embodiments of the hybrid type club head, the CG has a CGy position in the range of -3mm to -12mm. In some embodiments, the hybrid type club head has a CGy position in the range of -3mm to -8mm, or 8mm to -12mm. In some embodiments, the hybrid type club head has a CGy position in the range of -4mm to -8mm, -5mm to -9mm, -6mm to -10mm, -7mm to -11mm, or 8mm to -12mm. In some embodiments, the hybrid type club head has a CGy position of about -3mm, -4mm, -5mm, -6mm, -7mm, -8mm, -9mm, -10mm, -11mm, or 12mm.

[0210] In various embodiments of a driver-type club head, the CG has a CGz location greater than 38 mm, greater than 40 mm, greater than 42 mm, greater than 45 mm, or greater than 48 mm. In some embodiments, the driver-type club head has a CGz location in the range of 38 mm to 55 mm. In some embodiments, the driver-type club head has a CGz location in the range of 38 mm to 45 mm, or 45 mm to 55 mm. In some embodiments, the driver-type club head has a CGz location of about 38 mm, 39 mm, 40 mm, 41 mm, 42 mm, 43 mm, 44 mm, 45 mm, 46 mm, 47 mm, 48 mm, 49 mm, 50 mm, or 55 mm.

[0211] For various embodiments of fairway wood-type club heads, the CG can have a CGz location greater than 25 mm, greater than 28 mm, or greater than 30 mm. In some embodiments, the fairway wood-type club head has a CGz location in the range of 25 mm to 40 mm. In some embodiments, the fairway wood-type club head has a CGz location in the range of 25 mm to 32 mm, or 32 mm to 40 mm. In some embodiments, the fairway wood-type club head has a CGz location of about 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, 36 mm, 37 mm, 38 mm, 39 mm, or 40 mm.

[0212] For various embodiments of the hybrid-type club head, the CG can have a CGz location greater than 15 mm, greater than 18 mm, greater than 20 mm, greater than 22 mm, or greater than 24 mm. In some embodiments, the hybrid-type club head has a CGz location in the range of 15 mm to 30 mm. In some embodiments, the hybrid-type club head has a CGz location in the range of 15 mm to 25 mm, or 25 mm to 30 mm. In some embodiments, the hybrid-type club head has a CGz location between 16 mm to 26 mm, 17 mm to 27 mm, 18 mm to 28 mm, 19 mm to 29 mm, or 20 mm to 30 mm. In some embodiments, the hybrid-type club head has a CGz location of about 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, or 30 mm.

[0213] As mentioned above and with reference to Figures 2 to 4, the center of gravity (CG) defines the origin of a coordinate system having CGx, CGy, and CGz axes. The CGx axis is parallel to the X axis, the CGy axis is parallel to the Y axis, and the CGz axis is parallel to the Z axis. Additionally, the club head has a moment of inertia Ixx (i.e., crown-to-sole moment of inertia) about the CGx axis and a moment of inertia Iyy (i.e., heel-to-toe moment of inertia) about the CGy axis. In many embodiments, the crown-to-sole moment of inertia Ixx and the heel-to-toe moment of inertia Iyy are increased or maximized based on the amount of discretionary mass available to the club head designer. The moment of inertia represents the golf club head's ability to resist twisting. A larger moment of inertia about the X axis increases the forgiveness of off-center high and low strikes. A larger moment of inertia about the Y axis increases the forgiveness of off-center heel and toe strikes.

[0214] For various embodiments of driver-type club heads, in many embodiments, the crown-to-sole moment of inertia Ixx is about 3000 g cm 2 It is larger than 3250g cm 2 It is larger than 3500g cm 2 Larger than 3750g-cm2, approximately 4000g cm 2 Larger, approx. 4250g cm 2 Larger, approx. 4500g cm 2 Larger, approx. 4750g·cm 2 Larger or about 5000g cm 2 For various embodiments of driver-type club heads, in many embodiments the crown-to-sole moment of inertia Ixx is 3000 g cm 2 From 5000g cm 2 In another embodiment, the crown to sole moment of inertia Ixx is between 3000 g cm 2 From 4000g cm 2 Between 4000g cm 2 From 5000g cm2 For example, the crown-to-sole moment of inertia Ixx can range between 3000 g cm 2 , 3100g·cm 2 , 3200g·cm 2 , 3300g·cm 2 , 3400g·cm 2 , 3500g·cm 2 , 3600g·cm 2 , 3700g·cm 2 , 3800g·cm 2 ,3900g·cm 2 ,4000g·cm 2 ,4100g·cm 2 ,4200g·cm 2 ,4300g·cm 2 ,4400g·cm 2 ,4500g·cm 2 ,4600g·cm 2 ,4700g·cm 2 ,4800g·cm 2 ,4900g·cm 2 , or 5000g·cm 2 It could be.

[0215] For various embodiments of fairway wood type club heads, in many embodiments the crown-to-sole moment of inertia Ixx is about 1200 g cm 2 It is larger than 1300g cm 2 It is larger than 1400g cm 2 It is larger than 1500g cm 2 It is larger than 1600g cm 2 It is larger than 1700g cm 2 It is larger than 1800g cm 2 or approximately 1900 g cm 2 In another embodiment, the crown-to-sole moment of inertia Ixx is greater than 1200 g cm 2 From 2200g cm 2 In another embodiment, the crown to sole moment of inertia Ixx can be between 1200 g cm 2From 1700g cm 2 Between 1700g cm 2 From 2200g cm 2 For example, the crown-to-sole moment of inertia Ixx can be between 1200 g cm 2 , 1300g·cm 2 , 1400g·cm 2 , 1500g·cm 2 , 1600g·cm 2 , 1700g·cm 2 , 1800g·cm 2 , 1900g·cm 2 , 2000g cm 2 , 2100g·cm 2 , or 2200 g cm 2 It could be.

[0216] For various embodiments of the hybrid type club head, in many embodiments, the crown-to-sole moment of inertia Ixx is about 880 g cm 2 It is larger than the 2 It is larger than 900g cm 2 It is larger than the 2 Larger, approx. 920g cm 2 Larger, approx. 930g cm 2 Larger, approx. 940g·cm 2 Larger, approx. 950g cm 2 Larger or about 960g cm 2 In another embodiment, the crown-to-sole moment of inertia Ixx is 880 g cm 2 From 1500g cm 2 In another embodiment, the crown to sole moment of inertia Ixx can be in the range of 880 g cm 2 From 1200g cm 2 , or 1200g cm 2 From 1500g cm 2 In another embodiment, the crown to sole moment of inertia Ixx can be in the range of 900 g cm 2 From 1300g cm 2, 1000g cm 2 From 1400g cm 2 , or 1100g cm 2 For example, the crown-to-sole moment of inertia Ixx can range from 880 g cm 2 , 900g·cm 2 , 920g·cm 2 , 930g·cm 2 , 940g·cm 2 , 950g·cm 2 , 960g·cm 2 ,970g·cm 2 ,980g·cm 2 ,990g·cm 2 , 1000g cm 2 , 1020g·cm 2 , 1100g·cm 2 , 1200g·cm 2 , 1300g·cm 2 , 1400g·cm 2 , or 1500g cm 2 It could be.

[0217] For various embodiments of driver-type club heads, in many embodiments, the heel-to-toe moment of inertia Iyy is about 4500 g cm 2 It is larger than 4800g cm 2 It is larger than 5000g cm 2 Larger than 5150g cm 2 It is larger than 5250g cm 2 It is larger than 5500g cm 2 It is larger than 5750g cm 2 or approximately 6000 g cm 2 In other embodiments, the heel-to-toe moment of inertia Iyy can be greater than 4500 g-cm2 to 6000 g cm 2 In another embodiment, the heel-to-toe moment of inertia Iyy can be between 4500 g cm 2 From 5200g cm 2 Between 5200g cm 2 From 6000g cm2 For example, the heel-to-toe moment of inertia Iyy can range between 4500 g cm 2 , 4600g·cm 2 , 4700g·cm 2 , 4800g·cm 2 , 4900g·cm 2 , 5000g·cm 2 , 5100g·cm 2 , 5200g·cm 2 , 5300g·cm 2 ,5400g·cm 2 , 5500g·cm 2 , 5600g·cm 2 , 5700g·cm 2 , 5800g·cm 2 , 5900g·cm 2 , or 6000 g cm 2 The range may be:

[0218] In various embodiments of a fairway wood type club head, the heel-to-toe moment of inertia Iyy is about 2700 g cm 2 It is larger than 2800g cm 2 It is larger than 2900g cm 2 It is larger than 3000g cm 2 It is larger than the 2 It is larger than 3200g cm 2 or approximately 3300 g cm 2 In another embodiment, the heel-to-toe moment of inertia Iyy can be greater than 2700 g cm 2 From 3500g cm 2 In another embodiment, the heel-to-toe moment of inertia Iyy can range from 2700 g cm 2 From 3100g cm 2 Between 3100g cm 2 From 3500g cm 2 In another embodiment, the heel-to-toe moment of inertia Iyy can range from 2700 g cm 2 From 3200g cm 2, or 3200 g cm 2 From 3500g cm 2 For example, the heel-toe moment of inertia Iyy can range from 2700 g cm 2 , 2800g·cm 2 , 2900g·cm 2 , 3000g cm 2 , 3100g·cm 2 , 3200g·cm 2 , 3300g·cm 2 , 3400g·cm 2 , or 3500 g cm 2 It could be.

[0219] For various embodiments of the hybrid club head, in many embodiments, the heel-to-toe moment of inertia Iyy is about 2400 g cm 2 It is larger than 2500g cm 2 It is larger than 2600g cm 2 It is larger than 2700g cm 2 It is larger than 2800g cm 2 It is larger than 2900g cm 2 or approximately 3000 g cm 2 In another embodiment, the heel-to-toe moment of inertia Iyy can be greater than 2400 g cm 2 From 3200g cm 2 In another embodiment, the heel-to-toe moment of inertia Iyy can range from 2400 g cm 2 From 2700g cm 2 , or 2700 g cm 2 From 3200g cm 2 In another embodiment, the heel-to-toe moment of inertia Iyy can range from 2400 g cm 2 From 2900g cm 2 , 2500g·cm 2 From 3000g cm 2 , 2600g·cm 2 From 3100g cm 2 , or 2700 g cm 2 From 3200g cm2 For example, the heel-to-toe moment of inertia Iyy can range from 2400 g cm 2 ,2500g·cm 2 , 2600g·cm 2 , 2700g·cm 2 , 2750g·cm 2 , 2800g·cm 2 , 2850g·cm 2 , 2900g·cm 2 , 2950g·cm 2 , 3000g cm 2 , 3100g·cm 2 , or 3200 g cm 2 It could be.

[0220] In various embodiments of a driver-type club head, the composite moment of inertia (i.e., the sum of the crown-to-sole moment of inertia Ixx and the heel-to-sole moment of inertia Iyy) is greater than or equal to 8000 g cm 2 Larger, 8500g cm 2 Larger, 9000g cm 2 Larger, 9500g cm 2 Larger, 10000g cm 2 Larger, 11000g cm 2 Larger than 12000g cm 2 It could be bigger.

[0221] In various embodiments of a fairway wood type club head, the composite moment of inertia (i.e., the sum of the crown-to-sole moment of inertia Ixx and the heel-to-sole moment of inertia Iyy) is 4000 g cm 2 Larger, 4100g cm 2 Larger, 4200g cm 2 Larger, 4300g cm 2 Larger, 4400g cm 2 Larger, 4500g cm 2 Larger, 4600g cm 2 Larger, 4700g cm 2 Larger or 4800g cm 2It could be bigger.

[0222] In various embodiments of the hybrid club head, the composite moment of inertia (i.e., the sum of the crown-to-sole moment of inertia Ixx and the heel-to-sole moment of inertia Iyy) is greater than or equal to 3500 g cm 2 Larger, 3600g cm 2 Larger, 3700g·cm 2 Larger, 3800g cm 2 Larger, 3900g·cm 2 Larger, 4000g cm 2 Larger, 4100g cm 2 Larger or 4200g cm 2 It could be bigger.

[0223] (example) A. Example 1 - Club Head with Slit and Crown Return A comparative example was conducted comparing a control club head with an exemplary embodiment according to aspects of the present invention. The exemplary embodiment was a club head similar to the club head illustrated in FIG. 18. The exemplary embodiment includes a slit and a striking face crown return. The striking face crown return is formed from the same high strength material as the striking face. The striking face crown return extends from the top of the striking face to a front portion of the crown. The striking crown return of the exemplary embodiment has a thickness of about 0.025 inches. The control club head includes a slit and a face insert such that the crown return is formed from a different material than the striking face. The crown return of the control club head was about 0.035 inches. The slit of the control club head and the exemplary embodiment have the same shape and characteristics.

[0224] The data was collected using Finite Element Analysis (FEA). The FEA simulation involved a golf ball impacting the center of the face at approximately 100 MPH. The FEA simulation determined that the exemplary embodiment had an increase in ball velocity of 0.67 MPH over the control club head. Thus, the striking face crown return, where the crown return is made of the same material as the striking face, provided improved ball velocity over the control club head lacking the striking face crown return. The striking face crown return allows the crown to be thinner, resulting in more bending upon impact with the golf ball resulting in increased ball velocity.

[0225] B. Example 2 - Comparison of flexure insert and control insert The comparative examples are conducted using finite element analysis (FEA). The FEA tests compare the performance of an exemplary club head with a flexure insert according to an embodiment of the present invention to a control club head with an insert. The exemplary flexure insert used in the tests is similar to the insert of FIGS. 6-9. The flexure insert includes a slit with a U-shaped spring member and a cap. The control club head includes a slit with a single viscoelastic material. The slit shape and other club head features of the control and exemplary club heads are substantially the same.

[0226] FEA testing is expected to show that the exemplary club heads will produce approximately 0.5 MPH to 5 MPH increases in ball speed over the control club heads.

[0227] (item) Item 1: A golf club head comprising: a striking face having a striking surface for impacting a golf ball; and a body having a crown, a sole, a heel, a toe, and a rear end, the striking face and the body being configured to be secured together to enclose a hollow interior cavity, the sole defining a slit adjacent the striking face, the slit providing an opening communicating the hollow interior cavity with an exterior of the club head, the slit having a forward edge adjacent the striking face and a rear edge opposite the forward edge, the forward edge and the rear edge being configured to be secured together to the striking face. the slit defines a boundary of a sole, the slit is configured to receive a flexure insert, the flexure insert comprises a spring member and a cap, the spring member comprises a first material having a first modulus of elasticity, the cap comprises a second material having a second modulus of elasticity, the first modulus of elasticity is greater than the second modulus of elasticity, the flexure insert is connected to a forward edge and a rearward edge of the slit, the flexure insert fills the opening and seals the internal cavity, and the flexure insert is configured to flex with the sole upon impact of a golf ball.

[0228] Item 2: The golf club head of item 1, wherein the spring component is at least partially embedded within the cap.

[0229] Item 3: The golf club head of item 1, wherein the first material is selected from the group consisting of plastic, composite thermoset, steel, stainless steel, spring steel, titanium, and aluminum.

[0230] Item 4: The golf club head according to item 1, wherein the first elastic modulus is between 20 GPa and 210 GPa.

[0231] Item 5: The golf club head of item 1, wherein the second material is an injection molded polymer.

[0232] Item 6: The golf club head according to item 1, wherein the second elastic modulus is between 0.1 GPa and 30 GPa.

[0233] Item 7: The golf club head of item 1, wherein the slit further comprises a front recess formed on a front surface of the slit and a rear recess formed on a rear surface of the slit.

[0234] Item 8: A golf club head as described in Item 7, wherein the spring part has a front wall and a rear wall, the front wall has a forward projection extending forward from the front wall, and the rear wall has a rearward projection extending rearward from the rear wall, the forward projection configured to be received within the front recess, and the rear projection configured to be received within the rear recess.

[0235] Item 9: The golf club head of item 1, wherein the slit has a slit length measured as the heel-to-toe distance between a heel-most point of the slit and a toe-most point of the slit, and the spring component has a spring component length that is the heel-to-toe distance from the heel-most point of the spring component to the toe-most point of the spring component, and the spring component length is between 10% and 50% of the slit length.

[0236] Item 10: The golf club head described in Item 9, wherein the slit further comprises a slit heel portion located on the heel side of the club head, a slit toe portion located on the toe side of the club head, and a slit central portion located between the slit heel portion and the slit toe portion, the spring component being located within the slit central portion, and no spring component being present in the slit heel portion or the slit toe portion.

[0237] Item 11: The golf club head of item 1, further comprising an inner mass pad integrally formed on an inner surface of the sole, the inner mass pad rearward of the slit and spaced from the slit by a portion of the sole.

[0238] Item 12: The golf club head of item 11, wherein the inner mass pad has a mass between 25 grams and 40 grams.

[0239] Item 13: A golf club head comprising: a striking face having a striking surface and a geometric center for impacting a golf ball; and a body having a crown, a sole, a heel, a toe, and a rear end, the striking face and the body being configured to be secured together to enclose a hollow interior cavity, the striking face further comprising a crown return extending rearwardly from a top of the striking face, the crown return forming at least a forward portion of the crown, the sole defining a slit proximate the striking face, the slit providing an opening communicating the hollow interior cavity with an exterior of the club head, the slit having a forward edge adjacent the striking face and a rear edge opposite the forward edge, the forward edge and the rear edge defining a boundary of the slit. a slit configured to receive a flexure insert, the flexure insert comprising a spring member and a cap, the spring member comprising a first material having a first modulus of elasticity, the cap comprising a second material having a second modulus of elasticity, the first modulus of elasticity being greater than the second modulus of elasticity, the flexure insert connected to a forward edge and a rearward edge of the slit, the flexure insert filling the opening and sealing the internal cavity, the flexure insert configured to flex with the sole during impact of a golf ball, and the club head achieving an increase in ball velocity of between 0.5 mph and 4.5 mph at a club head speed of 100 mph compared to a similar club head comprising an insert without the spring member.

[0240] Item 14: The golf club head of item 13, wherein the crown return has a crown return thickness of less than 0.030 inches.

[0241] Item 15: The golf club head of item 13, wherein the striking face further comprises an upper periphery located along a rear edge of the crown return, the upper periphery forming an interface between the striking face and the crown.

[0242] Item 16: The golf club head of item 15, wherein the crown return has a crown return depth measured in a front-to-back direction from the geometric center to the upper outer periphery, the crown return depth being greater than 0.50 inches.

[0243] Item 17: A golf club head comprising: a striking face having a striking surface for impacting a golf ball; and a body having a crown, a sole, a heel, a toe, and a rear end, the striking face and the body configured to be secured together to enclose a hollow interior cavity, the sole defining a slit adjacent the striking face, the slit providing an opening communicating the hollow interior cavity with an exterior of the club head, the slit having a forward edge adjacent the striking face and a rear edge opposite the forward edge, the forward edge and the rear edge defining a boundary of the slit, the slit configured to receive a flexible insert. 16. A golf club head comprising: a flexure insert comprising a spring member and a cap, the spring member comprising a first material and the cap comprising a second material, the spring member comprising a front wall, a rear wall, and a U-shaped top wall, the U-shaped top wall curvingly extending into the interior cavity connecting the front wall and the rear wall, the slit further comprising a forward recess formed in a front surface of the slit and a rear recess formed in a rear surface of the slit, the front wall comprising a forward protrusion extending forwardly therefrom and the rear wall comprising a rear protrusion extending rearwardly therefrom, the forward protrusion configured to be received within the forward recess and the rear protrusion configured to be received within the rear recess.

[0244] Item 18: The golf club head of item 17, wherein the spring component is at least partially embedded within the cap.

[0245] Item 19: The golf club head of item 18, wherein the first material is selected from the group consisting of plastic, composite thermoset, steel, stainless steel, spring steel, titanium, and aluminum.

[0246] Item 20: The golf club head of item 19, wherein the second material is an injection molded polymer.

Claims

1. A golf club head, a striking face having a striking surface for impacting a golf ball; a body having a crown, a sole, a heel, a toe, and a rear end; the striking face and the body are configured to be secured together to enclose a hollow interior cavity; the sole defines a slit adjacent the striking face, the slit providing an opening communicating the hollow interior cavity with an exterior of the club head; the slit has a forward edge adjacent the striking face and a rearward edge opposite the forward edge; the forward edge and the rearward edge define a boundary of the slit; The slit is configured to receive a flexure insert; the flexure insert comprises a spring component and a cap; the spring component comprises a first material having a first elastic modulus; the cap comprises a second material having a second modulus of elasticity; the first elastic modulus is greater than the second elastic modulus; the flexure insert is connected to the forward and rearward edges of the slit; the flexure insert fills the opening and seals the internal cavity; The flexure insert is configured to flex with the sole upon impact with a golf ball.

2. The golf club head of claim 1 , wherein the spring element is at least partially embedded within the cap.

3. The golf club head of claim 1 , wherein the first material is selected from the group consisting of plastic, composite thermoset, steel, stainless steel, spring steel, titanium, and aluminum.

4. The golf club head of claim 1 , wherein the first elastic modulus is between 20 GPa and 210 GPa.

5. The golf club head of claim 1 , wherein the second material is an injection molded polymer.

6. The golf club head of claim 1 , wherein the second elastic modulus is between 0.1 GPa and 30 GPa.

7. The golf club head of claim 1 , wherein the slit further comprises a front recess formed in a front surface of the slit and a rear recess formed in a rear surface of the slit.

8. The spring component includes a front wall and a rear wall. the front wall includes a forward projection extending forwardly from the front wall; the rear wall includes a rear projection extending rearwardly from the rear wall; the forward projection is configured to be received within the forward recess; The golf club head of claim 7 , wherein the rearward projection is configured to be received within the rearward recess.

9. the slit has a slit length measured as the heel-to-toe distance between a heel-most point of the slit and a toe-most point of the slit; the spring component has a spring component length that is a heel-to-toe distance from a heel-most point of the spring component to a toe-most point of the spring component; The golf club head of claim 1 , wherein the spring component length is between 10% and 50% of the slit length.

10. the slit further comprises a slit heel portion located on the heel side of the club head, a slit toe portion located on the toe side of the club head, and a slit central portion located between the slit heel portion and the slit toe portion, The spring part is located in the slit central portion, 10. The golf club head of claim 9, wherein the slit heel portion and the slit toe portion are free of the spring components.

11. an inner mass pad integrally formed on an inner surface of the sole; The golf club head of claim 1 , wherein the inner mass pad is rearward of the slit and spaced from the slit by a portion of the sole.

12. The golf club head of claim 11 , wherein the inner mass pad has a mass between 25 grams and 40 grams.

13. A golf club head, a striking face having a striking surface and a geometric center for impacting a golf ball; a body having a crown, a sole, a heel, a toe, and a rear end; the striking face and the body are configured to be secured together to enclose a hollow interior cavity; the striking face further comprising a crown return extending rearwardly from a top portion of the striking surface, the crown return forming at least a forward portion of the crown; the sole defines a slit adjacent the striking face, the slit providing an opening communicating the hollow interior cavity with an exterior of the club head; the slit has a forward edge adjacent the striking face and a rearward edge opposite the forward edge; the forward edge and the rearward edge define a boundary of the slit; The slit is configured to receive a flexure insert; the flexure insert comprises a spring component and a cap; the spring component comprises a first material having a first elastic modulus; the cap comprises a second material having a second modulus of elasticity; the first elastic modulus is greater than the second elastic modulus; the flexure insert is connected to the forward and rearward edges of the slit; the flexure insert fills the opening and seals the internal cavity; the flexure insert is configured to flex with the sole during impact with a golf ball; A golf club head, wherein the club head realizes an increase in ball velocity of between 0.5 mph and 4.5 mph at a club head speed of 100 mph compared to a similar club head with an insert without a spring component.

14. The golf club head of claim 13 , wherein the crown return has a crown return thickness of less than 0.030 inches.

15. the striking face further comprising an upper periphery located along a rear edge of the crown return; The golf club head of claim 13 , wherein the upper periphery forms an interface between the striking face and the crown.

16. the crown return has a crown return depth measured in a front-to-rear direction from the geometric center to the upper periphery; The golf club head of claim 15 , wherein the crown return depth is greater than 0.50 inches.

17. A golf club head, a striking face having a striking surface for impacting a golf ball; a body having a crown, a sole, a heel, a toe, and a rear end; the striking face and the body are configured to be secured together to enclose a hollow interior cavity; the sole defines a slit adjacent the striking face, the slit providing an opening communicating the hollow interior cavity with an exterior of the club head; the slit has a forward edge adjacent the striking face and a rearward edge opposite the forward edge; the forward edge and the rearward edge define a boundary of the slit; The slit is configured to receive a flexure insert; the flexure insert comprises a spring component and a cap; the spring component comprises a first material; the cap comprises a second material; the spring part includes a front wall, a rear wall, and a U-shaped top wall; a U-shaped top wall that curves into the interior cavity and connects the front wall and the rear wall; The slit further includes a front recess formed on a front surface of the slit and a rear recess formed on a rear surface of the slit, the front wall includes a forward projection extending forwardly from the front wall; the rear wall includes a rear projection extending rearwardly from the rear wall; the forward projection is configured to be received within the forward recess; The golf club head, wherein the rearward projection is configured to be received within the rearward recess.

18. The golf club head of claim 17 , wherein the spring element is at least partially embedded within the cap.

19. 20. The golf club head of claim 18, wherein the first material is selected from the group consisting of plastic, composite thermoset, steel, stainless steel, spring steel, titanium, and aluminum.

20. The golf club head of claim 19 , wherein the second material is an injection molded polymer.

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