Patent Application
20130324308
Aspects of this invention relate generally to golf clubs and golf club heads. Particular example aspects relate to a golf club head having a ball striking surface with a stiffening feature.
Golf is enjoyed by a wide variety of players—players of different genders and dramatically different ages and/or skill levels. Golf is somewhat unique in the sporting world in that such diverse collections of players can play together in golf events, even in direct competition with one another (e.g., using handicapped scoring, different tee boxes, in team formats, etc.), and still enjoy the golf outing or competition. These factors, together with the increased availability of golf programming on television (e.g., golf tournaments, golf news, golf history, and/or other golf programming) and the rise of well known golf superstars, at least in part, have increased golf's popularity in recent years, both in the United States and across the world.
Golfers at all skill levels seek to improve their performance, lower their golf scores, and reach that next performance “level.” Manufacturers of all types of golf equipment have responded to these demands, and in recent years, the industry has witnessed dramatic changes and improvements in golf equipment. For example, a wide range of different golf ball models now are available, with balls designed to complement specific swing speeds and/or other player characteristics or preferences, e.g., with some balls designed to fly farther and/or straighter; some designed to provide higher or flatter trajectories; some designed to provide more spin, control, and/or feel (particularly around the greens); some designed for faster or slower swing speeds; etc. A host of swing and/or teaching aids also are available on the market that promise to help lower one's golf scores.
Being the sole instrument that sets a golf ball in motion during play, the golf club also has been the subject of much technological research and advancement in recent years. For example, the market has seen improvements in golf club heads, shafts, and grips in recent years. Additionally, other technological advancements have been made in an effort to better match the various elements of the golf club and characteristics of a golf ball to a particular user's swing features or characteristics (e.g., club fitting technology, ball launch angle measurement technology, etc.).
Because golf clubs typically are designed to contact the ball at or around the center of the face, off-center hits may result in less energy being transferred to the ball, thereby decreasing the distance of the shot. The energy or velocity transferred to the ball by a golf club also may be related, at least in part, to the flexibility of the club face at the point of contact, and can be expressed using a measurement called coefficient of restitution (“COR”). Accordingly, it would be advantageous to provide a golf club head having a flexible ball striking surface and other structural features that provide an improved or maximized COR. The present invention seeks to overcome certain of the limitations discussed above and other drawbacks of the prior art, and to provide features not heretofore available.
The following presents a simplified summary in order to provide a basic understanding of some aspects of the invention. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to the description below.
A golf club and golf club head structures having a ball striking face, a frame member and a perimeter stiffening element are disclosed herein. The golf club head may be a wood-type club head. Further, the club head may have an interior cavity. The golf club head may have a volume greater than or equal to 440 cc and a ball striking face area greater than or equal to 32 cm2
According to certain aspects, the frame member may extend rearwardly from a perimeter of the ball striking face. The perimeter stiffening element may extend along at least a portion of the perimeter of the ball striking face and further may extend from the ball striking face to the frame member.
According to other aspects, a thickness of the perimeter stiffening element may be greater than or equal to a thickness of the ball striking face adjacent to the perimeter stiffening element. A width of the perimeter stiffening element may be greater than or equal to a thickness of the frame element adjacent to the perimeter stiffening element.
Further, the thickness of the ball striking face adjacent to the perimeter stiffening element may be greater than the thickness of the frame member adjacent to the perimeter stiffening element.
The coefficient of restitution of the club head may be greater than or equal to 0.830.
According to certain other aspects, the cross-sectional area of the perimeter stiffening element may be greater than or equal to 10 mm2. Further, the thickness of the perimeter stiffening element may be greater than or equal to 4.0 mm and/or the width of the perimeter stiffening element may be greater than or equal to 3.0 mm. Even further, the out-of-plane bending stiffness (EIB) of the perimeter stiffening element may range from 1500 in2-lb to 2500 in2-lb. The torsional stiffness (GJ) of the perimeter stiffening element may range from 1200 in2-lb to 1600 in2-lb.
The ratio of the thickness of the perimeter stiffening element to the width to the perimeter stiffening element may be greater than or equal to 1:1. The ratio of the thickness of the perimeter stiffening element to the thickness of the ball striking face adjacent to the perimeter stiffening element may range from approximately 2:1 to approximately 4:1. The thickness of the perimeter stiffening element may range from approximately 2.5 mm to approximately 7.5 mm. The width of the perimeter stiffening element may have a value that is within ±20% of the value of the thickness of the perimeter stiffening element.
The thickness of the frame member may be less than or equal to 1.0 mm. Optionally the thickness of the frame member adjacent to the perimeter stiffening element may range from approximately 0.25 mm to approximately 1.25 mm. According to some embodiments, the thickness of the ball striking face may be less than or equal to 2.0 mm. Alternatively, the thickness of the ball striking face adjacent to the perimeter stiffening element may range from approximately 0.5 mm to approximately 2.5 mm. The ratio of the thickness of the ball striking face adjacent to the perimeter stiffening element to the thickness of the frame member adjacent to the perimeter stiffening element may be greater than or equal to approximately 1.5:1.
According to some aspects, the perimeter stiffening element may be integrally joined to the frame member. Further, the perimeter stiffening element may be integrally joined to the ball striking face. According to certain embodiments, the ball striking face, the frame member and the perimeter stiffening element may be unitarily formed. Further, the ball striking face, the frame member and the perimeter stiffening element may be formed of a titanium material.
According to some aspects, a golf club and golf club head structures have a ball striking face, a frame member and a perimeter stiffening element. The ball striking face may be configured to flex inward upon contacting a golf ball. The frame member may extend around and be integrally joined to the ball striking face. The perimeter stiffening element may extend around at least majority of a perimeter of the ball striking face. Further, the perimeter stiffening element may be joined to an interior surface of the ball striking face and to an interior surface of the frame member. The ball striking face may have a thickness, measured adjacent to the perimeter stiffening element, which ranges from approximately 1.25 mm to approximately 2.5 mm. The frame member may have a thickness, measured adjacent to the perimeter stiffening element, which ranges from approximately 0.40 mm to approximately 1.0 mm. The perimeter stiffening element may have a cross-sectional area greater than or equal to 20 mm2. The coefficient of restitution of the club head may be greater than or equal to 0.830.
The present invention is illustrated by way of example and not limited in the accompanying figures, in which like reference numerals indicate similar elements throughout, and in which:
The reader is advised that the various parts shown in these drawings are not necessarily drawn to scale.
The following description and the accompanying figures disclose features of golf clubs and golf club head structures in accordance with examples of the present invention.
When a player hits a golf ball, both the golf ball and the golf club head (particularly, the ball striking face) deform—the golf ball compressing in diameter against the ball striking face and the ball striking face flexing inward. Because the ball is of a more resilient material and its mass is so much smaller than the ball striking face of the club head, the golf ball causes a greater energy loss than the amount that the face of the head may lose when its face flexes inward—in fact, the golf ball may be responsible for up to 80% of the loss of energy between the two. As a result, if the ball striking face can be designed so that the face deflects more, the golf ball will compress less, resulting in a greater ball speed velocity in relation to the player's swing speed.
The development of thinner ball striking faces leads to a more flexible face, thereby reducing the energy loss associated with deformation of the golf ball. A limit case of this concept would be analogous to a trampoline, which consists of a thin membrane, supported by springs and a frame. However, if the frame of the trampoline is too flexible, both control and speed of the rebounding ball can be lost.
For flexible ball striking faces, it was determined that adding a stiffening ring around the perimeter (i.e., where the ball striking face meets the front frame of the club head) improves the overall response and increases the COR. Modeling and analyses have shown that this stiffening ring isolates the club head energy at the ball striking face, where it is best poised to return more energy to the ball during the rebound process. Thus, less energy flows beyond the ball striking face, such that, for example, outward deformations of the front frame of the club head adjacent to the ball striking face are reduced and tend to be more localized. Additionally, analyses show that peak deformations of the ball striking face with the stiffening ring occur earlier during the impact time than of the ball striking face without a stiffening ring. It is expected that the combination of these factors would allow the club head having the stiffening ring around the perimeter of the balls striking face to return more energy to the ball, rather than dissipating it through club head front frame vibrations. With more energy being returned to the ball, a significant increase in COR is expected to be produced.
These findings may be applied to any of various golf club heads and various types of golf clubs in accordance with aspects described herein. For instance, a perimeter stiffening element may be used with wood-type golf clubs and golf club heads, e.g., clubs and club heads typically used for drivers and fairway woods, as well as for “wood-type” utility or hybrid clubs, or the like. Such club head structures may have little or no actual “wood” material and still may be referred to conventionally in the art as “woods” (e.g., “metal woods,” “fairway woods,” etc.). Further, a perimeter stiffening element may also be used with iron-type, hybrid-type, utility type, etc. golf clubs and golf club head structures.
In accordance with the above, aspects of this invention relate to golf club and golf club head structures. In some examples, a golf club head may include a golf club head body having a crown, a sole, a toe, a heel, a rear and a ball striking face. The crown, sole, toe, heel, rear and ball striking face may define an at least substantially enclosed interior portion of the golf club head. The portion of the club head that extends rearwardly from the ball striking face may be referred to as a frame member.
The golf club and golf club head includes a perimeter stiffening element extending around the inside perimeter edge of the ball striking face. The perimeter stiffening element couples the ball striking face to the frame member. The perimeter stiffening element may extend along just a portion of the perimeter of the ball striking face or it may extend completely around the perimeter of the ball striking face. The perimeter stiffening element may be continuous or discontinuous. Further, the perimeter stiffening element may have a constant cross-sectional area and/or shape or the area and/or the shape may vary as the perimeter stiffening element extends around the perimeter of the ball striking face. Additionally, the perimeter stiffening element may be integrally formed with the ball striking face and/or with the frame member (or portions thereof). Alternatively, the perimeter stiffening element may be formed separately from the ball striking face and/or the frame member and joined to the ball striking face and/or the frame member in a secondary or subsequent operation. The perimeter stiffening element may be formed of the same or different material(s) than the ball striking face and/or the frame member.
According to certain aspect, the thickness of the perimeter stiffening element may be greater than or equal to a thickness of the ball striking face adjacent to the perimeter stiffening element, and the width of the perimeter stiffening element may be greater than or equal to a thickness of the frame element adjacent to the perimeter stiffening element. For example, the thickness of the perimeter stiffening element may be greater than one-and-a-half times the thickness of the ball striking face or greater than twice the thickness of the ball striking face. The width of the perimeter stiffening element may be greater than twice the thickness of the frame element, or even greater than triple the thickness of the frame element.
According to some aspects, the thickness of the perimeter stiffening element may be greater than or equal to the width of the perimeter stiffening element.
Further, the thickness of the ball striking face adjacent to the perimeter stiffening element may be greater than the thickness of the frame member adjacent to the perimeter stiffening element.
Given the general description of various example aspects of the invention provided above, more detailed descriptions of various specific examples of golf clubs and golf club head structures according to the invention are provided below.
The following discussion and accompanying figures describe various example golf clubs and golf club head structures in accordance with various aspects of the present invention. When the same reference number appears in more than one drawing, that reference number is used consistently in this specification and the drawings to refer to the same or similar parts throughout.
“Integrally joined” refers to a single piece, component, element, member, etc. that cannot be separated into multiple pieces or subcomponents without structural damage. Integrally joining techniques including unitarily forming the piece or component (i.e., manufacturing the piece as a single unit from the raw materials used to form the piece), and further includes irreversibly or permanently joining (such as adhesively joining, cementing, welding, brazing, soldering, or the like) originally separate pieces so that the pieces effectively become inseparable without structural damage.
“Transverse” means extending across or in a cross direction to a line, plane, edge, surface, etc., defined at an actual or virtual intersection point, but does not necessarily imply a perpendicular intersection.
Specific examples and features of golf club heads and golf club structures will be described in detail below in conjunction with the example golf club structures illustrated in
Additionally, a grip or handle (not shown) may be provided on a proximal end of the shaft 12. Any suitable grip material may be used without departing from this invention, including, by way of non-limiting examples: elastomeric materials, leather materials, rubber or other materials including cord or other fabric material embedded therein, polymeric materials, and the like. The grip may be secured to the shaft 12 in any suitable manner, including in conventional manners known and used in the art, e.g., using adhesives or cements; using welding, soldering, brazing or the like; using mechanical connectors (such as threads, retaining elements, etc.); etc. As another example, the grip may be integrally formed as a unitary, one-piece construction with the shaft 12.
In the example structure shown in
As additional examples or alternatives, in order to reduce the weight of the club head 14, one or more portions of the club head 14 may be made from a composite material, such as from carbon fiber composite materials that are conventionally known and used in the art. Other suitable composite materials that may be used for one or more portions of the club head 14 include, for example: fiberglass composite materials, aramid fiber reinforced composite materials, basalt fiber reinforced composite materials, polymer materials, ceramic materials, etc. The composite material(s) may be incorporated as part of the club head 14 in any suitable manner, including in conventional manners that are known and used in the art.
In the embodiment of
The ball striking face 17 is located at the front of the club head 14, and has a ball striking surface 17b located thereon and an inner surface 17c opposite the ball striking surface 17b, as best illustrated in
The ball striking face 17 may be formed from a single piece of material. For example, the ball striking face 17 may be formed of a metal material, such as a titanium alloy (e.g., Ti-6Al-4V). Other high strength materials, such as stainless steel or other steel alloys may be used. Additionally, vitreous alloys such as iron-boron, nickel-copper, nickel-zirconium, nickel-phosphorous, and the like may be used. Further, the ball striking face 17 may be formed from ceramics, composites and/or other metal. Even further, the striking face may be formed from amorphous metals, including alloys containing zirconium, titanium, beryllium, niobium, copper, nickel, etc., using a bulk-solidifying process. Such bulk-solidifying amorphous metals are disclosed, for example, in U.S. Pat. No. 7,357,731, issued Apr. 15, 2008, to Johnson et al., and hereby incorporated by reference in its entirety.
The ball striking face 17 may be forged, drawn, cast, machined, injection bmolded, powder-metal formed, milled, etched, etc. Alternatively, the ball striking face 17 may be formed from multiple pieces of material that are subsequently joined together.
Referring to
Further, the ball striking face 17 may generally be provided with a loft angle, such that at the point of impact (and also at the address position, i.e., when the club head is positioned on the ground adjacent to the golf ball prior to the initiation of the backswing) the ball striking surface 17b is not perpendicular to the ground. Generally, the loft angle is meant to affect the initial upward trajectory of the golf ball—increased loft induces greater ball trajectory heights. Standard loft for a driver is around 10 degrees, although lofts may frequently range from 7 or 8 degrees up to 14 degrees.
Even further, the ball striking face 17 may be provided with a face angle, such that at the point of impact the ball striking surface 17b is not parallel to the orientation of the shaft. Generally, the face angle is meant to counteract a particular golfer's tendency to hook or slice his shots—an “open face” is meant to counteract a tendency to hook; a “closed face” is meant to counteract a tendency to slice.
Although, bulge and roll and face and loft angles have been described above with respect to the ball striking face 17 and the ball striking surface 17b, generally, the ball striking face 17 may be considered to be a relatively flat, planar component. Referring to
According to certain aspects, the club head 14 may include a front body portion 14a and an aft body portion 14b. In certain embodiments, the two portions 14a, 14b may actually be two components that are formed separately and then subsequently assembled to form the club head. Thus, for example as shown in
The front body portion 14a may include the ball striking face 17, extending generally within a plane, with a frame member 19, extending generally transversely to the plane of the ball striking face 17 and rearwardly from the perimeter 17d of the ball striking face 17. The perimeter 17d may define the intersection of the ball striking face 17 with the frame member 19. The frame member 19 may extend continuously around the perimeter 17d of the ball striking face 17.
Further, the frame member 19 may include and/or form portions of the crown 18, the toe 20, the sole 28, the heel 24 and/or the hosel region 26. In some embodiments, the frame member 19 may integrally and/or unitarily formed with the crown 18, the toe 20, the sole 28, the heel 24 and/or the hosel region 26. Thus, the frame member 19 is that portion of the club head that lies adjacent to and frames and extends around the ball striking face 17. In those embodiments wherein the frame member 19 may be separately formed and/or distinguishable from the more aftward portions of the club head, the rearward extent of the frame member 19 may be relatively constant, such as shown in
According to some aspects, the frame member 19 may have a wall thickness t2 that is less than the thickness t1 of the ball striking face 17. Thus, for example, the thickness t2 of the frame member 19 may be constant and may be approximately 0.025 inches (approximately 0.635 mm). Optionally, the thickness t2 of the frame member 19 may range from 0.010 inches (approximately 0.25 mm) to 0.075 inches (approximately 1.91 mm), ranging from 0.010 inches (approximately 0.25 mm) to 0.050 inches (approximately 1.25 mm), ranging from 0.020 inches (approximately 0.508 mm) to 0.050 inches (approximately 1.25 mm), or even ranging from 0.015 inches (approximately 0.40 mm) to 0.035 inches (approximately 0.90 mm). According to other aspects, the thickness t2 of the frame member 19 may vary. Thus, for example, the frame member 19 may be thicker in the sole region than in the crown region. As another example, the frame member 19 may be thickest closest to the ball striking face 17 and thinner as it extends rearwardly away from the face 17. Further, by way of non-limiting example, the frame member 19 may be considered to be a thin-walled shell structure, i.e., a structure that generally reacts loads by developing in-plane stresses.
According to certain aspects, a ratio of the thickness t1 of the ball striking face 17 to the thickness t2 of the frame member 19 may be greater than approximately 1.5:1, greater than approximately 2.5:1, greater than approximately 3:1, greater than approximately 4:1, even greater than approximately 5:1, or even up to approximately 6:1. Thus, for example, if the thickness t1 of the ball striking face 17 is 0.075 inches (approximately 1.905 mm) and the thickness t2 of the frame member 19 is 0.025 inches (approximately 0.635 mm), the ratio is approximately 3:1. If the thickness t1 of the ball striking face 17 varies and/or if the thickness t2 of the frame member 19 varies, the ratio may be determined using the minimum thicknesses t1, t2.
Referring to
The perimeter stiffening element 117 is located where the frame member 19 joins the ball striking face 17. Specifically, the perimeter stiffening element 117 is located on the interior surface of the ball striking face 17 and extends along the perimeter of the ball striking face 17. According to certain aspects, the perimeter stiffening element 117 may extend completely around the perimeter 17d of the ball striking face 17. The perimeter stiffening element 117 is also located on the interior surface of the frame member 19. In other words, the perimeter stiffening element 117 extends from the ball striking face 17 to the frame member 19, further reinforcing the attachment of the frame member to the ball striking face 17.
The perimeter stiffening element 117 stiffens the ball striking face 17 and also stiffens the frame member 19. Further, the perimeter stiffening element 117 stiffens the attachment of the ball striking face 17 to the frame member 19, such that the frame member 19 and the ball striking face 17 are more strongly coupled to each other. Thus, deflections and stresses of the ball striking face 17 and of the frame member 19 are decreased in the vicinity of their intersection.
As noted above, if the ball striking face 17 has a very thin thickness t1, a high COR response due to a trampoline-like effect may result upon impact with a golf ball. However, as also noted above, if the perimeter of the ball striking face 17 is too flexible, control over the rebounding golf ball may be reduced. The presence of the perimeter stiffening element 117 may allow the ball striking face 17 to be made of a thin or relatively thinner material than would be possible for club heads without a perimeter stiffening element 117, and thus may allow for more flexibility of the ball striking face 17 and ultimately a higher COR, with greater control over the rebounding golf ball. Additionally, the perimeter stiffening element 117 may aid in preventing over flexing of the ball striking face 17 and/or of the frame member 19. Over flexing could result in failure of the ball striking face 17 and/or of the frame member 19 (e.g., breaking, cracking, stress fatigue, etc.).
Referring to
According to other aspects, the thickness t3 of the perimeter stiffening element 117 may be related to the thickness t1 of the ball striking face 17. For example, the thickness t3 of the perimeter stiffening element 117 may be greater than or equal to the thickness t1 of the ball striking face 17. By way of non-limiting example, the thickness t3 of the perimeter stiffening element 117 may be greater than or equal to twice the thickness t1 of the ball striking face 17. Optionally, the ratio of the thickness t3 of the perimeter stiffening element 117 to the thickness t1 of the ball striking face 17 may be greater than or equal to 3:1, or even greater than or equal to 4:1. Alternatively, it may be desirable to limit the thickness t3 of the perimeter stiffening element 117 to between two and four times the thickness t1 of the ball striking face 17 or even to between one and three times the thickness t1 of the ball striking face 17.
Still referring to
According to certain aspects, the width w3 of the perimeter stiffening element 117 may be related to the thickness t3 of the perimeter stiffening element 117. For example, the ratio of the width w3 of the perimeter stiffening element 117 to the thickness t3 of the perimeter stiffening element 117 may be approximately 1:1. By way of other non-limiting examples, the width w3 of the perimeter stiffening element 117 may be greater than the thickness t3 of the perimeter stiffening element 117; greater than or equal to twice or even thrice the thickness t3 of the perimeter stiffening element 117. On the other hand, it may be desirable to have the thickness t3 of the perimeter stiffening element 117 greater than the width w3 of the perimeter stiffening element 117. Thus, the ratio of the thickness t3 of the perimeter stiffening element 117 to the width w3 of the perimeter stiffening element 117 may be greater than 1:1; greater than 1.5:1, greater than 2:1, or even greater than 3:1.
According to other aspects, the width w3 of the perimeter stiffening element 117 may be related to the thickness t2 of the frame member 19. For example, the width w3 of the perimeter stiffening element 117 may be greater than or equal to the thickness t2 of the frame member 19. By way of non-limiting examples, the width w3 of the perimeter stiffening element 117 may be greater than or equal to the twice or even thrice the thickness t2 of the frame member 19. Further, it may be desirable to provide a perimeter stiffening element 117 having a width w3 that is greater than or equal to four times, six times, eight times or even ten times the thickness t2 of the frame member 19. Alternatively, the width w3 of the perimeter stiffening element 117 may lie between four and ten times the thickness t2 of the frame member 19 or even to between five and eight times the thickness t2 of the frame member 19.
According to other aspects, the perimeter stiffening element 117 may have a cross-sectional area (A) that is approximately 26 mm2 (approximately 0.04 square inches). When determining the cross-sectional area A of the perimeter stiffening element 117 the areas due to the thicknesses t1 and t2 of the ball striking face 17 and the frame member 19, respectively, would typically not be included in the calculation. By way of non-limiting example, the perimeter stiffening element 117 may have a cross-sectional area A that ranges from approximately 5 mm2 to approximately 35 mm2, from approximately 10 mm2 to approximately 30 mm2, from approximately 15 mm2 to approximately 25 mm2, or even from approximately 15 mm2 to approximately 20 mm2. It is expected that, generally, the greater the cross-sectional area, the stiffer the perimeter stiffening element will be, and the greater the isolation of the dynamic response of the ball striking face 17 from the dynamic response of the frame member 19. Thus, by way of other non-limiting examples, the perimeter stiffening element 117 may have a cross-sectional area A that is greater than approximately 5 mm2, greater than approximately 10 mm2, greater than approximately 15 mm2, greater than approximately 20 mm2, or even greater than approximately 25 mm2.
A simplified, axisymmetric analytical model developed with an LS-DYNA transient finite element analysis program was developed to investigate various potential high ball speed design concepts.
As a baseline, an analytical model similar to that shown in
Further, as seen by comparing
Without the perimeter stiffening element 117, the ball striking surface 17 may flex more than it would with the perimeter stiffening element 117 present, which may result in greater stress and/or deformation of the material of the ball striking surface 17 and thus increased likelihood of cracking, fatigue, strain failure, etc. Further, without the perimeter stiffening element 117, the thin-walled frame member 19 may flex more than it would with the addition of the perimeter stiffening element 117, which may result in greater stress and/or deformation of the material of the frame member 19 and the corresponding increased likelihood of cracking, fatigue, strain failure, etc. Thus, for both these reasons, the inclusion of the perimeter stiffening element 117 in the front body portion 14a may allow a club head designer to maintain the COR response of the club head within USGA limits while preventing or greatly inhibiting detrimental overflexing of the ball striking surface 17 and/or the thin-walled frame member 19.
According to some aspects, the perimeter stiffening element 117 may have a varying flexibility or stiffness along portions of the perimeter 17d of the ball striking face 17. The stiffness may vary due to varying a bending stiffness EIB of the perimeter stiffening element 117 and/or varying a torsional stiffness GJ of the perimeter stiffening element 117. For purposes of this disclosure, E refers to Young's modulus (i.e., a material property related to the elastic stress-strain deformation of the material), IB refers to a bending moment of inertia (i.e., a property of the cross-section related to out-of-plane bending of the perimeter stiffness element relative to its midplane), G refers to a modulus of rigidity of the material (i.e., a shear modulus), and J refers to a torsional or polar moment of inertia (i.e., a property of the cross-section related to twisting of the perimeter stiffening element relative to its central axis). By way of non-limiting examples, the bending stiffness EIB may range from 500 in2-lb to 5000 in2-lb, from 1000 in2-lb to 3000 in2-lb, or even from 1500 in2-lb to 2500 in2-lb. Further, by way of non-limiting examples, the torsional stiffness GJ may range from 100 in2-lb to 3000 in2-lb, 500 in2-lb to 2000 in2-lb, or even from 1200 in2-lb to 1600 in2-lb. Thus, it is understood, given the benefit of the present disclosure, that the bending and/or torsional stiffness of the perimeter stiffening element 117 may be optimized by a golf club designer to achieve the desired COR while avoiding detrimental stresses and/or strains in the ball striking face 17 and/or in the frame member 19.
Referring back to
According to certain aspects, the front body portion 14a, which includes the ball striking face 17, the frame member 19 and the perimeter stiffness element 117, may be formed from a single piece of material. For example, the front body portion 14a may be formed of a metal material, such as a titanium alloy (e.g., Ti-6Al-4V). Other high strength materials, such as stainless steel or amorphous metallic alloys, may be used. The front body portion 14a may be forged, drawn, cast, machined, injection molded, powder-metal formed, milled, etched, etc. Thus, by way of non-limiting example, the front body portion 14a may be unitarily formed as a cup face structure. Alternatively, the front body portion 14a may be formed from multiple pieces of material that are subsequently integrally joined. Thus, by way of another non-limiting example, the ball striking face 17 and the frame member 19 may be unitarily formed as a separate piece and the perimeter stiffness element 117 may be formed as a separate piece or pieces of material that are subsequently integrally joined to ball striking face 17 and to the frame member 19 such as by welding, brazing, cementing, adhesively joining, etc.
Still further, the perimeter stiffening element 117 may be formed in a variety of different ways. According to certain aspects, the perimeter stiffening element 117 may be unitarily constructed with the ball striking face 17, such as by cutting, milling, forging, or other such technique. It is understood that the perimeter stiffening element 117 may be unitarily constructed with the ball striking face 17 and then subsequently shaped or finished with secondary machining operations, such as milling, grinding, etc. In other embodiments, for example, in the case of a multi-piece ball striking face 17, the perimeter stiffening element 117 may be formed separately and subsequently integrally joined with the ball striking face 17. Again, secondary machining operations may be used to shape or refine the ball striking face 17 and/or the perimeter stiffening element 117.
Optionally, the perimeter stiffness element 117 may formed from multiple pieces. For example, as shown in
The perimeter stiffening element 117 may be formed of any suitable material, including metals, non-metals and composites. For example, the perimeter stiffening element 117 may be formed of a lightweight material, such as a lightweight metal. Some example lightweight metals that may be used include steel, titanium and titanium alloys, aluminum and aluminum alloys, magnesium and magnesium alloys, etc. Additionally or alternatively, the perimeter stiffening element 117 may be formed, at least in part, of non-metallic materials, including composite materials, such as carbon fiber composite materials, fiberglass composite materials, basalt fiber composite materials, polymer materials, ceramics, etc. Even further, the perimeter stiffening element 117 may be formed of more than one material.
According to other aspects, the club head 14 may be provided with other features. For example, referring back to
As another example feature, the club head 14 may include a groove 29 formed about a portion of a periphery of the club head 14. Groove 29 may function as a Kammback feature during at least certain portions of the downswing of the golf club 10. As illustrated in
Generally, golf club heads may generally include a plurality of different regions, segments, portions, ends, etc. In an example embodiment, a golf club head may generally include a ball striking face, a rear, a toe, a heel, a crown, a sole and/or a hosel region that may, taken together, generally, enclose an interior of the golf club head. The golf club heads may include a multiple piece construction and structure, or if desired, various portions of the club head structure may be integrally formed with one another, as a unitary, one piece construction. Optionally, the various portions of the club head structure (such as the sole, the crown, the face, the rear, etc.) individually may be formed from multiple pieces of material and subsequently joined using integral joining techniques (e.g., thereby forming an integrally joined crown, an integrally joined sole, an integrally joined aft body portion, etc.) without departing from this invention. Also, as other alternative, if desired, a one piece, unitarily constructed front body portion may be attached to a one piece, unitarily constructed club head aft body portion (optionally, a hollow body, etc.). As even another alternative, the entire club head may be made or formed as a single, one piece, unitary construction.
As mentioned above, aspects of the invention described herein may be used with various other types of golf clubs and golf club head structures, including hybrid type clubs, iron-type clubs, and the like. Although the above description of golf club structures is generally directed to wood-type golf club heads, nothing in the disclosure should be viewed as limiting use of the invention as described herein to use with only wood-type golf clubs.
The present invention is described above and in the accompanying drawings with reference to a variety of example structures, features, elements, and combinations of structures, features, and elements. The purpose served by the disclosure, however, is to provide examples of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the embodiments described above without departing from the scope of the present invention, as defined by the appended claims. For example, the various features and concepts described above may be used individually and/or in any combination or subcombination without departing from this invention.
