Golf club head with enhanced shaft joint strength

Abstract

To provide a golf club that improves the joint strength between the head and shaft while achieving the desired swing weight without adversely affecting mass properties and MOI. [Solution] The club head is provided with a hosel that receives the tip of the shaft. The tip of the shaft defines the shaft joint area and the effective joint area. The mechanism is designed to increase the effective shaft joint area with the hosel and improve the joint strength between the club head and the shaft. In some embodiments, the mechanism includes microgrooves located within the shaft joint area. The microgrooves increase the effective joint area and provide multidirectional resistance to forces applied to the shaft 140. In some embodiments, the mechanism includes a ferrule that includes a weight mechanism that serves as a substitute for a tip weight. In some embodiments, the mechanism includes a hot-melt weight located within the shaft.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 217,683, filed Jul. 7, 2021, and U.S. Provisional Application No. 63 / 140,747, filed Jan. 22, 2021, the contents of which are hereby incorporated by reference in their entirety.

[0002] The present disclosure generally relates to golf clubs, and more particularly to golf club shafts having various mechanisms for improving joint strength.

Background Art

[0003] A typical golf club includes a shaft and a club head connected to the bottom end of the shaft, thereby forming a head - shaft connection (the "connection portion"). During a swing, the connection portion is subjected to multi - directional swing forces, also known as vertical resistance and torsional forces. During the swing, the club head is pulled away from the shaft, thereby applying vertical resistance, and further, the club head rotates or twists relative to the shaft, thereby applying a torsional force to the connection portion. In addition to the swing forces, the connection portion is subjected to an impact force when it collides with the ball. To prevent breakage of the club head, the head - shaft connection must be strong enough to withstand these applied forces.

[0004] The connection portion is defined where the tip of the shaft is received by the hosel. To fix the shaft to the club head, an epoxy material is used. The epoxy material forms a joint or micro - link between the tip of the shaft and the hosel. The strength of the connection portion depends on the effective bonding surface, or the amount of the outer surface of the shaft that directly contacts the inner surface of the hosel. As the effective bonding area increases, the bonding strength also increases. The connection portion requires an effective bonding area sufficient to prevent the club head from flying off and causing a fatal breakage.

[0005] The effective joint area is limited by the shaft insertion depth and the hosel depth. In some golf clubs, the effective joint area is further limited by other components disposed within the hosel, such as ferrules, adjustable hosel sleeves, or chip weights. These components are used to improve other characteristics of the golf club. For example, chip weights provide a means of balancing the club head and shaft and achieving a desired swing weight. However, these components require space within the hosel, which reduces the allowable effective joint area between the shaft and the hosel. In some golf clubs, to compensate for these additional components, the hosel is made larger (longer) to achieve a sufficient effective joint area. However, forming a larger hosel requires moving mass from a desired location to the hosel, which negatively impacts the mass characteristics and sacrifices the performance of the entire club head.

Summary of the Invention

Problems to be Solved by the Invention

[0006] In view of the above, further development regarding appropriate reinforcement of golf club mechanisms can improve the performance of golf clubs while maintaining sufficient structural integrity of the golf clubs. Therefore, there is a need in the art for a golf club that improves the joint strength between the head and the shaft while achieving a desired swing weight without negatively affecting the mass characteristics and MOI.

Brief Description of the Drawings

[0007] [[ID=十六]] [Figure 1] FIG. 1 is an exploded cross-sectional view of a golf club according to a first embodiment.

[0008] [Figure 2A] FIG. 2 is a cross-sectional view of the golf club of FIG. 1.

[0009] [Figure 2B]This is a cross-sectional view of a golf club according to the second embodiment.

[0010] [Figure 3A] This is a side view of a golf club shaft equipped with microgrooves according to the first embodiment.

[0011] [Figure 3B] Figure 3A is a magnified view of the microgroove.

[0012] [Figure 4] This is a side view of a golf club shaft equipped with microgrooves according to a second embodiment.

[0013] [Figure 5] This is a side view of a golf club shaft equipped with microgrooves according to a third embodiment.

[0014] [Figure 6] This is a side view of a golf club shaft equipped with microgrooves according to the fourth embodiment.

[0015] [Figure 7] This is a side view of a golf club shaft equipped with microgrooves according to the fifth embodiment.

[0016] [Figure 8] This is a side view of a golf club shaft equipped with microgrooves according to the sixth embodiment.

[0017] [Figure 9] This is a side view of a golf club shaft equipped with microgrooves according to the seventh embodiment.

[0018] [Figure 10] This is a side view of a golf club shaft equipped with microgrooves according to the eighth embodiment.

[0019] [Figure 11] This is a perspective view of a ferrule according to the first embodiment.

[0020] [Figure 12A] This is a perspective view of a ferrule according to a second embodiment.

[0021] [Figure 12B] Figure 12A is a perspective view of the internal weight.

[0022] [Figure 13A] This is a cross-sectional view of a ferrule according to a third embodiment.

[0023] [Figure 13B] Figure 13A is a perspective view of the weight ring of the ferrule.

[0024] [Figure 14] This is a side view of the ferrule according to the fourth embodiment.

[0025] [Figure 15A] This is an exploded view of a golf club head equipped with a hot-melt chip weight.

[0026] [Figure 15B] Figure 15A is a cross-sectional view of a golf club head. [Modes for carrying out the invention]

[0027] This specification describes golf clubs that incorporate various mechanisms to increase the effective contact area between the shaft and the club head without adversely affecting the club head characteristics. In some embodiments, the existing hosel and tip weight geometry is maintained, and the shaft incorporates mechanisms according to aspects of the present invention, such as microgrooves. In other embodiments, these hosel and tip weight geometry is modified, and the hosel and tip weight are modified to include mechanisms such as weighted ferrules or to be replaced by mechanisms such as hot-melt tip weights.

[0028] In some embodiments, as described above, the mechanism for increasing the effective bonding area between the shaft and the golf club head includes microgrooves. Microgrooves enhance the connection strength in several ways. Firstly, the microgrooves are recessed in the shaft and define multiple side walls, which increases the effective bonding area. The side walls and floor of the microgrooves provide a larger surface area than the flat shaft surface. The additional bonding area enhances the bond strength because the epoxy has a larger surface area to form the joint between the hosel and the shaft. Secondly, the microgrooves form paths or channels that facilitate a uniform flow of epoxy around the shaft tip, which prevents pressure buildup and air pockets between the hosel and the rest of the golf club head. Finally, the side walls of each microgroove can be oriented in different directions to provide greater resistance to normal forces and / or torsional forces. Microgrooves create paths that distribute stress more uniformly across the entire connection. In some embodiments, the microgrooves may be discrete lines, discrete shapes, intersecting lines, or intersecting shapes. Microgrooves can extend circumferentially around the effective bonding area or can be formed as groups. A group comprises multiple microgrooves having various shapes. Microgrooves can be formed in various patterns that define the group. The sidewalls of the microgrooves may be smooth or serrated. Microgrooves can be applied to the tip of a shaft, the rear end of a shaft, or the inner surface of a grip. Microgrooves may include other mechanisms, such as ridges, notches, rough areas, or any other mechanisms that increase the roughness of the effective bonding area.

[0029] In other embodiments, as described above, the mechanism for increasing the effective contact area between the shaft and the golf club head includes weight elements that replace conventional perimeter weights and swing weight elements, such as tip weights. By removing the tip weight, the shaft can be inserted deeper into the hosel, thereby maximizing the shaft insertion depth. These weight elements can also be used in combination with smaller tip weights. In some embodiments, the weight element is a ferrule with a weight. The weight can be visible from the outside of the ferrule or hidden within the ferrule. In alternative embodiments, the ferrule is formed from a high-density material. In another embodiment, the weight element is a hot-melt weight located within the shaft body. These weight elements provide substantial mass to add weight to the club head, thereby allowing the tip weight to be removed or replaced with a smaller tip weight. The weight elements described herein maximize the effective contact area to enhance the head-shaft connection.

[0030] The terms “equipped with,” “included,” “possessed,” “possess,” “can possess,” and “included” as used herein, and their conjugations, are intended to be open-ended transitional phrases, terms, or words that do not exclude the possibility of additional actions or structures. The singular forms “a,” “and,” and “the” include plural references unless the context clearly indicates otherwise. This disclosure also contemplates other embodiments “equipped with,” “consisting of,” and “essentially consisting of,” the embodiments or elements presented herein, whether expressly described or not.

[0031] The term “about” as used herein in the following disclosures is used in relation to a quantity containing a stated value and has a meaning determined by the context (e.g., including some degree of error associated with at least a certain measurement of a particular quantity). The modifier “about” should also be considered to disclose a range defined by the absolute values ​​of two endpoints. For example, the expression “about 2 to about 4” also discloses the range “2 to 4”. The term “about” may represent plus or minus 10% of a given number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean 0.9 to 1.1. Other meanings of “about” may become apparent from the context.

[0032] The terms “first,” “second,” “third,” and “fourth” as used in the following disclosure are used to distinguish similar elements and are not necessarily used to indicate a specific sequential or chronological order. It should be understood that the terms used in this manner are interchangeable under appropriate circumstances to allow the embodiments described herein to operate in an order other than, for example, those illustrated or described herein. Furthermore, the terms “includes” and “have,” and their inflections, are intended to cover non-exclusive inclusion, and a process, method, system, item, device, or apparatus that includes an enumeration of elements is not necessarily limited to those elements and may include other elements not expressly enumerated or that are specific to such process, method, system, item, device, or apparatus.

[0033] The terms “circumferential,” “parallel,” “nonparallel,” “perpendicular,” and “non-perpendicular” as used in the following disclosure are for illustrative purposes only and are not necessarily used to describe permanent relative positions. It should be understood that such terms are interchangeable under appropriate circumstances to enable embodiments of the apparatus, methods, and / or products described herein to operate in orientations other than those illustrated or described herein.

[0034] As used herein, “joint strength” may refer to the strength of the epoxy material at a head-shaft connection or a grip-shaft connection. Joint strength can be quantified by the energy required to break the joint between the joint surface and the inner surface of the hosel or grip.

[0035] The "coordinate system" as used herein includes a loft plane tangent to the geometric center of the striking surface. When the club head is in the address position, the club head defines a contact surface tangent to the sole. This coordinate system is defined by the origin at the geometric center of the golf club head striking surface. The center of the striking surface defines the origin for a coordinate system having x, y, and z axes. The x-axis is a horizontal axis extending through the center of the surface in a direction parallel to the contact surface, from near the heel to near the toe. The y-axis is a vertical axis extending through the center of the surface in a direction perpendicular to the contact surface, from near the sole to near the crown. The y-axis is perpendicular to the x-axis. The z-axis is a horizontal axis extending through the center of the surface in a direction parallel to the contact surface, from near the front to near the rear. The z-axis is perpendicular to the x and y axes. The x-axis extends in the positive direction toward the heel. The y-axis extends in the positive direction toward the crown. The z-axis extends in the positive direction toward the rear.

[0036] As used herein, the “center of gravity coordinate system” is defined by the center of gravity of the golf club head. The center of gravity is located within the coordinate system defined above. The center of gravity may also have positions on the x, y, and z axes. The center of gravity further defines the origin of the coordinate system having the CGx, CGy, and CGz axes. The CGx axis extends through the CG from near the heel to near the toe. The CGy axis extends through the CG from near the crown to near the sole, and the CGy axis is perpendicular to the CGx axis. The CGz axis extends through the CG from near the front to near the rear, and is perpendicular to both the CGx and CGy axes.

[0037] As used herein, the “effective bonding region” may be the surface region of the outer shaft surface that is in direct contact with the inner surface of the hosel bore. The effective bonding region may extend circumferentially around the outer shaft surface and may be located along the effective bonding depth. The effective bonding region may be located within the shaft bonding region. Figure 2A shows an example of an effective bonding region 154.

[0038] As used herein, “effective joint depth” may refer to the depth of the outer shaft surface in direct contact with the inner surface of the hosel bore. Figure 2A shows an example of an effective joint depth 156, which can be measured along the longitudinal axis 110 from the bottom edge of the ferrule 2012 to the bottom end of the shaft 144. Figure 2B shows another example of an effective joint depth 156, which is measured along the longitudinal axis 110 from the bottom edge of the ferrule 2012 to the tip weight 192.

[0039] As used herein, “epoxy” may refer to any adhesive or resin mixture used to bond the shaft to the club head or grip. Epoxy is applied to the shaft bonding area and used as a means to secure the connection. Epoxy can form a joint between the shaft bonding area and the inner surface of the hosel or grip.

[0040] As used herein, “ferrule depth” may refer to the length of the lower portion of the ferrule that enters the hosel or the centering region. Figure 2A shows an example of a ferrule depth 2030, which is measured along the longitudinal axis 110 from the ferrule ledge 2018 to the bottom edge of the ferrule 2012.

[0041] As used herein, the “ferrule surface” may refer to the surface area of ​​the lower portion of the ferrule that is in contact with the hosel joint region. Figure 2A shows an example of a ferrule surface 2046, which extends circumferentially around the lower portion of the ferrule and is located at a ferrule depth of 2030.

[0042] As used herein, "golf club" may refer to an iron-type golf club, a wood-type golf club, or a putter-type golf club. Iron-type golf clubs may have cavity, cavity back, hollow body, forged, cast, or crossover golf club heads. Wood-type golf clubs may have driver, fairway, or hybrid golf club heads.

[0043] As used herein, “head-shaft connection” may refer to a connection between the outer surface of the shaft tip and the inner surface of the hosel. The head-shaft connection may be used interchangeably with the “connection.”

[0044] As used herein, the “hosel joint region” may be the surface region of the inner surface of the hosel bore that joins to the shaft. Figure 1 shows an example of a hosel joint region 138, which extends circumferentially around the inner surface of the hosel bore and is located along the hosel depth 134.

[0045] As used herein, “hosel depth” may refer to the total depth of the hosel bore measured along the longitudinal axis. Figure 1 shows an example of a hosel depth 134, which is measured from the hosel bore rim 126 to the hosel bore base 128.

[0046] As used herein, "iron-type golf club head" includes the top rail, sole, heel, toe, rear, and striking surface. Generally, an iron-type golf club head comprises a single, integrated body in which the striking surface and hosel are formed together. In other embodiments, the striking surface may be formed separately.

[0047] As used herein, the “longitudinal axis” may be an axis extending from the geometric center at the top of the shaft to the geometric center at the bottom of the shaft. The shaft may be a symmetrical cylinder bisected by the longitudinal axis.

[0048] As used herein, “moment of inertia” may refer to moment of inertia Ixx and / or Iyy. Moment of inertia Ixx is defined around the CGx axis (i.e., crown-sole moment of inertia), and moment of inertia Iyy is defined around the CGy axis (i.e., heel-toe moment of inertia). Moment of inertia represents the ability of a golf club head to withstand twisting.

[0049] As used herein, “normal force” may be a tensile force applied normal to or perpendicular to the cross-sectional area of ​​a shaft. In other words, a normal force can be applied parallel to the longitudinal axis of the shaft. A normal force may be used interchangeably with a “compressive force” or a “pulling force.” A normal force applied to a shaft may cause a uniform normal stress throughout the cross-sectional area of ​​the object.

[0050] As used herein, the “shaft joint region” may be the surface region of the shaft that joins with the inner surface of the hosel bore. The shaft joint region may extend circumferentially around the outer surface of the shaft and may be located at the shaft insertion depth. Figure 1 shows an example of a shaft joint region 150, which includes an effective joint region 154 and the outer surface of the ferrule 2046.

[0051] As used herein, “shaft insertion depth” may refer to the depth to which the shaft is inserted into the hosel hole. Figure 1 shows an example of a shaft insertion depth 152, which is measured along the longitudinal axis 110 from the shaft tip 144 to the ferrule ledge 2018.

[0052] As used herein, “tip weight” can be a cylindrical weight component that can be inserted into a hosel and held in place with epoxy material. The tip weight can be formed from a high-density material. Figure 2B shows an example of a tip weight 190 located near the hosel base 128 and having a tip weight depth 192 measured along the longitudinal axis 110.

[0053] As used herein, “torsional force” may be a twisting force applied parallel or tangentially to the cross-sectional area of ​​the shaft. In other words, a torsional force may be applied perpendicular to the longitudinal axis of the shaft. A torsional force can be used interchangeably with a torque or twisting force. A torsional force applied to a shaft may cause a distribution of shear stress across the entire cross-sectional area of ​​the shaft.

[0054] As used herein, the “transition step” may be a transition region located on the outer surface of the shaft near the bottom end. The transition step can be defined as the transition between the shaft joint surface and the remaining portion of the shaft located above the shaft joint region. In some embodiments, the transition step can be defined by a change in surface finish. For example, the portion of the shaft above the transition step may have a polished finish, while the portion of the shaft below the transition step may have a sandblasted finish. In other embodiments, the transition step can be defined by a change in the outer diameter of the shaft. For example, the portion of the shaft above the transition step may have a larger diameter than the portion of the shaft below the transition step.

[0055] As used herein, a “wood-type golf club head” may comprise a striking surface and a body fixed to each other to define a substantially closed / hollow internal volume. The club head comprises a crown, a sole opposite the crown, a heel, a toe opposite the heel, a front, and a rear opposite the front. The body may further include a skirt or trailing edge positioned adjacent to the crown and sole, the skirt extending from near the heel to near the toe of the club head.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art. In case of any conflict, the definitions in this document shall prevail. Preferred methods and materials similar to or equivalent to those described herein may be used in the practice or testing of the present invention. All publications, patent applications, patents, and other references referred herein are incorporated herein by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative and not intended to be limiting.

[0057] This specification describes a golf club that includes a mechanism to increase the bonding strength between the club head and the shaft. Bonding strength is increased when the effective bonding area is increased and epoxy can flow uniformly around the shaft. This can be achieved by increasing the bonding surface area while maintaining the current hosel and ferrule geometry, or by modifying the ferrule so that the current mechanism can be eliminated, thereby increasing the shaft insertion depth and bonding surface area.

[0058] The golf club described herein comprises a club head 100, a shaft 140, and a grip 160. The club head 100 comprises a body 120 and a hosel 122, the hosel 122 comprising a hosel hole 124. The hosel hole 124 is defined by an inner surface extending from a hosel rim 126 to a hosel base 128. The inner surface defines a hosel joint region 138 that interacts with the shaft 140. The hosel joint region 138 is the inner surface of the hole 122 used to join the hosel 122 to the shaft 140. The shaft 140 comprises a top end 142 that is received within the grip 160, a bottom end 144 that is received within the hosel hole 124, and an outer surface 146. The outer surface 146 defines a transition step 148 and a shaft joint region 150 near the bottom end 144. The shaft joint region 150 is the surface of the shaft 140 used to join the shaft 140 to the hosel 122. The shaft bottom end 144 is positioned within the hosel hole 124 such that the shaft joint region 150 is in contact with the hosel joint region 138. The interaction between the shaft joint region 150 and the hosel joint region 138 forms the connection between the club head 120 and the shaft 140. Furthermore, the configuration of the shaft joint region 150 and the hosel joint region 138 determines the strength of the head-shaft connection.

[0059] The portion of the shaft joint region 150 that is in direct contact with the hosel joint region 138 is known as the effective joint region 154. In most embodiments, the effective joint region 154 is smaller than the shaft joint region 150 and is limited by the presence of other components within the hosel bore. As discussed above, it is desirable to maximize the effective joint area 154 to enhance the head-shaft connection. One way to maximize the effective joint area 154 is to increase the effective joint depth 156 by removing additional components. The maximum effective joint depth 156 is equal to the shaft insertion depth 152, and the effective joint area 154 is equal to the shaft joint area 150. In such embodiments, the entire shaft joint region 150 is in direct contact with the hosel joint region 138. In other embodiments where additional components are present, the effective joint area 154 is maximized while remaining within the existing footprint.

[0060] For example, some golf clubs further include a ferrule 2000 positioned around the shaft 140. Referring to Figure 2A, the ferrule 2000 includes a lower portion that is inserted into the hosel hole 124 at a ferrule depth 2030. The lower portion of the ferrule 2000 includes an outer surface 2046 that contacts the hosel joint area 138, which prevents the shaft joint area 150 (at the ferrule depth 2030) from contacting the hosel joint area 138. This reduces the effective joint depth 156 by the amount of the ferrule depth 2030. In other embodiments, the golf club further includes a tip weight 190 located in the hosel hole base 128. The tip weight 190 occupies space within the hosel hole 124, thereby reducing the allowable shaft insertion depth 152. The effective joint area 154 is reduced by the amount of the tip weight depth 192. This disclosure describes several mechanisms designed to increase the effective bonding area 154 in order to enhance the bonding strength between the club head 100 and the shaft 140. The golf clubs described herein may have any combination of these mechanisms.

[0061] A. Golf club shafts with microgrooves As described below, the shaft 140 may have multiple microgrooves. The microgrooves increase the effective bonding area 154 without increasing the effective bonding depth 156. Microgrooves can be used to improve bonding strength while maintaining other desirable hosel mechanisms such as ferrules, tip weights, and hosel size.

[0062] Referring to Figures 3A-310, the golf club shaft 140 may further comprise multiple microgrooves. In some embodiments, the microgrooves are located within the shaft joining region 150. In other embodiments, the microgrooves are located only within the effective joining region 154. The microgrooves reinforce the head-shaft connection by increasing the effective joining area and providing multidirectional resistance to force. The microgrooves are recessed into the shaft, defining multiple sidewalls, each sidewall defining the depth of the microgroove and the sidewall surface area. The sidewall surface area provides additional area to the effective joining region 154. Thus, the microgrooves increase the effective joining area 154 without increasing the effective joining depth 156. The microgrooves are formed integrally with the shaft 140, which makes the microgrooves a versatile mechanism that can be applied to any shaft 140 without altering the existing footprint of the shaft 140 and / or hosel mechanism. In some embodiments, the microgroove may have two side walls and a planar base that define a U-shaped channel in cross-sectional view. In other embodiments, the microgroove may have two angled side walls that connect to form a V-shaped channel.

[0063] In addition to increasing the effective contact area 154, the microgrooves are oriented so that their sidewalls provide resistance to the various forces applied to the shaft 140 (and head-shaft connection) during the swing and impact with the golf ball. During the downswing, the shaft 140 is subjected to a normal force applied parallel to the longitudinal axis 110 in the direction from the rear end to the tip of the shaft 140, causing the club head to be pulled away from the shaft. The shaft 140 is also subjected to a torsional force applied perpendicular to the longitudinal axis 110 at impact with the golf ball, causing the golf club head to rotate around the shaft axis. The microgroove sidewalls provide resistance when oriented in a direction nonparallel to the applied forces. In other words, the microgroove sidewalls provide resistance to the normal force when oriented nonparallel to the longitudinal axis 110 and resistance to the torsional force when oriented nonperpendicular to the longitudinal axis 110.

[0064] Each microgroove defines a depth measured from the shaft outer surface 146 to the floor of each microgroove. Alternatively, the microgroove depth can also be called the height of the microgroove sidewall. In some embodiments, the sidewall is perpendicular to the shaft outer surface 146. In other embodiments, the sidewall is angled with respect to the shaft outer surface 146. The microgroove depth correlates with an increase in the sidewall surface area and the effective bonding area 154. The same amount of force applied to a larger surface area has less effect because the force is more widely distributed. Therefore, the microgroove depth is maximized to improve the bonding characteristics. However, the microgroove depth is dependent on the diameter of the shaft 140. The microgroove depth is limited to prevent the microgrooves from penetrating too deeply. Penetration that is too deep may impair the strength of the shaft 140.

[0065] Furthermore, the microgrooves provide epoxy pathways or channels extending circumferentially around the outer surface 146 of the shaft. These channels facilitate a uniform flow of epoxy around the shaft 140, which maximizes the surface area covered by epoxy and further enhances the bonding strength. Thus, the microgrooves take into account multidirectional forces, maximize the effective bonding area 154, and promote uniform epoxy coating. In some embodiments, the microgroove sidewalls are oriented in a direction nonparallel to and non-perpendicular to the longitudinal axis 110, as defined above, thereby providing resistance to both normal and torsional forces.

[0066] Microgrooves can be formed in any combination of discrete or intersecting shapes, with each shape having at least three sidewalls. Microgrooves can be formed as groups of at least two microgrooves. However, each group can have 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more microgrooves. Furthermore, microgrooves can be formed as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more groups of microgrooves. Microgrooves can be formed as multiple discrete or intersecting lines. Alternatively, microgrooves can also be formed as multiple randomly oriented elements. Microgrooves can be formed in any combination described herein. However, microgrooves can preferably be formed to provide resistance to both normal and torsional forces. The positioning and sizing of the microgrooves are selected to reinforce the head-shaft connection without compromising the strength of the shaft. As discussed below, microgrooves can be formed in various shapes and lines with various sizes.

[0067] The microgroove depth is between 0.0010 inches and 0.0050 inches. In some embodiments, the microgroove depth is approximately 0.0010 inches, 0.0015 inches, 0.0020 inches, 0.0025 inches, 0.0030 inches, 0.0035 inches, or less than 0.0040 inches. In some embodiments, the microgroove depth is between 0.0010 inches and 0.0025 inches, 0.0010 inches and 0.0050 inches, 0.0015 inches and 0.0030 inches, 0.0025 inches and 0.0040 inches, or 0.0035 inches and 0.0050 inches. In one exemplary embodiment, the microgroove depth is 0.0030 inches. Microgrooves can be applied to both graphite shafts and steel shafts. In some graphite shafts, the microgrooves are recessed into the outer resin layer of the shaft 140, but do not penetrate into the inner composite layer.

[0068] In some embodiments, the microgroove depth is constant throughout the microgroove, while in other embodiments, the microgroove depth varies throughout the microgroove. In some embodiments, the microgroove depth varies such that the microgroove is deeper near the shaft bottom end 144 and shallower towards the shaft top end 142. Conversely, in other embodiments, the microgroove depth varies such that the microgroove is deeper near the shaft top end 142 and shallower towards the shaft bottom end 144. The microgroove depth can vary in any pattern, or it can vary randomly. Furthermore, the depth can also vary in any direction within each individual microgroove.

[0069] The microgroove depth can be adjusted to provide microgrooves with greater yield strength in specific portions of the shaft joint area 150. For example, the shaft 140 may experience a non-uniform stress distribution due to applied torsional forces, and therefore, deeper microgrooves can be positioned where the effective joint area 154 experiences greater stress. For instance, the shaft 140 may experience greater stress at the top of the shaft joint area 150 than at the bottom due to torsional forces, and therefore, the top of the shaft joint area 150 benefits more from deeper microgrooves than the bottom. The microgroove depth is optimized to increase the effective joint area 154 without compromising the strength of the shaft 140. The microgroove length and width are similarly selected to provide greater yield strength in certain portions of the effective joint area 154.

[0070] Each microgroove further defines an individual microgroove length, measured along the longitudinal axis 110 from the point of the microgroove closest to the shaft bottom end 142 to the point closest to the shaft top end 144. Each microgroove further includes an individual microgroove width, measured circumferentially around the shaft 140 in a direction perpendicular to the longitudinal axis 110. The individual microgroove lengths and widths determine the increase in the effective bonding area 154.

[0071] In some embodiments, the length of individual microgrooves is constant throughout the microgroove, while in other embodiments, the length of individual microgrooves varies throughout the microgroove. In some embodiments, the length of individual microgrooves is less than 0.05 inches, 0.10 inches, 0.25 inches, 0.50 inches, 0.75 inches, 1.00 inches, 1.25 inches, 1.50 inches, 1.75 inches, 3.00 inches, 3.50 inches, or 5.00 inches. In some embodiments, the length of individual microgrooves is between 0.05 inches and 0.10 inches, 0.075 inches and 0.125 inches, 0.075 inches and 0.20 inches, 0.25 inches and 0.50 inches, 0.50 inches and 1.00 inches, 0.75 inches and 1.50 inches, 1.10 inches and 1.50 inches, 1.25 inches and 3.00 inches, or 2.00 inches and 5.00 inches. In one exemplary embodiment, the length of each individual microgroove is 0.75 inches. Microgrooves may have the same length as adjacent microgrooves or different lengths. The length of each individual microgroove can be adjusted to provide microgrooves with greater yield strength in specific portions of the shaft joint region 150. For example, longer microgrooves can be positioned where the shaft 140 is subjected to greater stress.

[0072] In some embodiments, the individual microgroove widths are constant throughout the microgroove, while in other embodiments, the individual microgroove widths vary throughout the microgroove. In some embodiments, the individual microgroove widths are less than 0.05 inches, 0.10 inches, 0.25 inches, 0.50 inches, 0.75 inches, or 1.00 inches. In some embodiments, the individual microgroove widths are between 0.05 inches and 0.50 inches, 0.075 inches and 0.125 inches, 0.075 inches and 0.20 inches, 0.25 inches and 0.50 inches, 0.30 inches and 0.75 inches, 0.50 inches and 1.00 inches, 0.75 inches and 1.50 inches, or 1.00 inches and 2.00 inches. In one exemplary embodiment, the individual microgroove width is 0.015 inches. The microgrooves may have the same width as adjacent microgrooves or different widths. The individual microgroove widths can be adjusted to provide microgrooves with greater endurance in specific portions of the shaft joint region 150. For example, wider microgrooves can be positioned where the shaft 140 is subjected to greater stress.

[0073] The surface area of each microgroove sidewall is determined by the depth, length, and width of each microgroove. The microgroove sidewalls increase the effective bonding area 154 and enhance the bonding strength by providing additional surface area for the epoxy to bond to. In some embodiments, the microgrooves increase the effective bonding area 154 to 0.01 in 2 , 0.05 in 2 , 0.10 in 2 , 0.25 in 2 , 0.50 in 2 , 0.75 in 2 , 1.00 in 2 , 1.25 in 2 , or 1.50 in 2The amount is increased by more than 5%. In some embodiments, the microgrooves increase the effective bonding area 154 by more than 5%, 10%, 15%, 20%, 30%, 50%, 75%, or 90%. In other embodiments, the microgrooves increase the effective bonding area 154 by an amount between 5% and 10%, 5% and 15%, 10% and 25%, 25% and 50%, 50% and 75%, or 75% and 90%. The microgrooves form microchannels that increase the effective bonding area 154. The increase in the effective bonding area 154 enhances the bonding strength in the head-shaft connection by providing more surface area for forming additional joints.

[0074] The microgrooves further comprise a total depth measured along the longitudinal axis from the microgroove closest to the shaft bottom end 144 to the microgroove closest to the shaft top end 142. The total microgroove depth is different from the individual microgroove depths. The total microgroove depth is the actual length of the shaft with the microgrooves. In some embodiments, the microgrooves cover the entire shaft joining region 150, and the total microgroove depth is equal to the shaft insertion depth. In other embodiments, the microgrooves are located only within the effective joining region 154, and the total microgroove depth is equal to the effective joining depth 156. In some embodiments, the total microgroove depth is greater than 0.90 inches, 1.00 inches, 1.10 inches, 1.20 inches, 1.30 inches, or 1.35 inches. In some embodiments, the total microgroove depth is between 0.50 inches and 1.00 inches, 0.50 inches and 1.50 inches, 0.60 inches and 0.90 inches, 0.70 inches and 1.10 inches, 0.80 inches and 1.10 inches, 1.20 inches and 1.75 inches, 1.50 inches and 3.00 inches, or 2.50 inches and 5.00 inches. In one exemplary embodiment, the total microgroove depth is 1.10 inches.

[0075] The total microgroove depth determines the portion of the shaft joint area 150 covered by the microgrooves. In some embodiments, the microgrooves cover between 10%–20%, 25%–50%, 25%–75%, 30%–80%, 50%–70%, 50%–90%, 60%–100%, or 75%–100% of the shaft joint area 150. The microgrooves are formed in a continuous pattern without large gaps between adjacent microgrooves. In some embodiments, the microgrooves are uniformly distributed, while in other embodiments, the microgrooves are concentrated across several portions of the shaft joint area 150. The microgroove sizing is selected to increase the effective joint area 154 without compromising the strength of the shaft 140. The microgroove sizing and morphology settings discussed above can be applied to various embodiments of the microgrooves described herein.

[0076] The golf clubs described herein may have any combination of the microgroove patterns described below. In some embodiments, the microgrooves are formed as lines, and in other embodiments, the microgrooves are formed in a specific shape. As discussed above, in some embodiments, each microgroove is recessed in the shaft 140 and defined by a plurality of side walls (or "side walls") and a planar base. In other embodiments, the microgroove is recessed in the shaft 140 and defined by two side walls that form a V-shaped or U-shaped channel. The orientation of the side walls is expressed with respect to the longitudinal axis 110. The side walls can be oriented horizontally (perpendicular to the longitudinal axis 110), vertically (parallel to the longitudinal axis 110), or obliquely (angled with respect to the longitudinal axis 110). The orientation of the microgrooves is selected to provide multidirectional resistance to forces applied to the golf club shaft. Each side wall may be a smooth continuous surface, or the side walls may be serrated. Furthermore, the microgrooves can be intersecting or discrete lines.

[0077] I. Microgrooves formed as lines In some embodiments, the microgrooves can be formed as multiple lines, as shown in Figures 3A-38. Microgrooves 1100, 1200, 1300, 1400, and 1500 are described using similar reference numbers. For example, microgrooves 1100, 1200, 1300, 1400, and 1500 comprise side walls 1110, 1210, 1310, 1410, and 1510, and floor sections 1120, 1220, 1320, 1420, and 1520.

[0078] In some embodiments (see Figures 3A and 3B), the microgrooves 1100 can extend circumferentially around the shaft 140 in a direction oblique to the longitudinal axis 110, such that the direction is neither perpendicular nor parallel. In other words, the microgrooves 1100 extend spirally around the shaft. The microgrooves 1100 have a first group 1130 and a second group 1140. The first group 1130 of the microgrooves 1100 extends spirally clockwise in the vertical direction around the shaft. The second group 1140 of the microgrooves 1100 extends spirally counterclockwise in the vertical direction around the shaft. The first and second groups 1130 and 1140 of the microgrooves 1100 intersect to form diamond-shaped projections between the microgrooves 1100.

[0079] The microgrooves 1100 form an angle with the longitudinal axis 110. The angle is measured from the longitudinal axis to the side wall 1110 of the microgrooves 1100. The angle can be greater than 0 degrees and less than 90 degrees, measured clockwise or counterclockwise from the longitudinal axis 110. For example, as shown in Figures 3A and 3B, one set of microgrooves 1100 forms an angle of 45 degrees when measured clockwise, and a second set of microgrooves forms an angle of 45 degrees when measured counterclockwise. In other embodiments, the microgrooves can form angles of 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 65 degrees, 70 degrees, 75 degrees, 80 degrees, or 85 degrees when measured clockwise or counterclockwise with respect to the longitudinal axis 110.

[0080] In other embodiments, as shown in Figure 4, the microgrooves 1200 can extend circumferentially around the shaft 140 in a direction perpendicular to the longitudinal axis 110, without intersecting. The side walls 1210 are parallel to each other and perpendicular to the longitudinal axis 110. The side walls 1210 provide resistance to normal forces.

[0081] In another embodiment, as shown in Figure 5, the microgrooves 1300 can extend in a direction parallel to the longitudinal axis 110. The microgrooves 1300 are circumferentially positioned around the shaft 140 and do not intersect. The side walls 1310 are parallel to each other and parallel to the longitudinal axis 110. The side walls 1310 provide resistance to torsional forces.

[0082] In another embodiment, as shown in Figure 6, the microgrooves may comprise a first plurality of microgrooves 1200 and a second plurality of microgrooves 1300. The side walls 1210 of the first plurality of microgrooves 1200 are parallel to each other and perpendicular to the longitudinal axis 110, and the side walls 1310 of the second plurality of microgrooves 1300 are parallel to each other and parallel to the longitudinal axis 110. The first plurality of microgrooves 1200 may be positioned above the second plurality of microgrooves 1300 or near the shaft top end 142. As shown in Figure 6, the first plurality of microgrooves 1200 may also be positioned below the second plurality of microgrooves 1300. The microgrooves 1200, 1300 provide resistance to normal and torsional forces.

[0083] Each of the first plurality of microgrooves 1200 and the second plurality of microgrooves 1300 comprises at least one microgroove. In some embodiments, the first and second plurality of microgrooves 1200, 1300 each comprise 10 to 20 microgrooves, 20 to 50 microgrooves, 10 to 30 microgrooves, 30 to 70 microgrooves, 50 to 100 microgrooves, 40 to 60 microgrooves, 50 to 150 microgrooves, or 30 to 50 microgrooves. In other embodiments, the microgrooves may further comprise a third plurality of microgrooves, a fourth plurality of microgrooves, or a fifth plurality of microgrooves.

[0084] In another embodiment, as shown in Figure 7, the microgrooves 1400 can extend circumferentially around the shaft 140 in a direction perpendicular to the longitudinal axis 110, without intersecting. The sidewalls 1410 define jagged or non-straight sidewall sections 1410. Each sidewall section 1410 is angled with respect to adjacent sidewall sections 1410. Furthermore, each sidewall section 1410 is oriented non-parallel and non-perpendicular to the longitudinal axis 110. The angled sidewall sections 1410 provide resistance to normal and torsional forces.

[0085] In another embodiment, as shown in Figure 8, the microgrooves 1500 can extend circumferentially around the shaft 140 at an angle to the longitudinal axis 110. In this embodiment, the microgrooves 1500 are generally parallel to each other. The microgrooves 1500 are similar to the microgrooves 1400 shown in Figure 7, with sidewalls 1510 defining sidewall sections 1510. The sidewall sections 1510 are angled with respect to adjacent sidewall sections 1510. Furthermore, each sidewall section 1510 is oriented non-parallel and non-perpendicular to the longitudinal axis 110. The angled sidewall sections 1510 provide resistance to normal and torsional forces.

[0086] II. Microgrooves formed in a specific shape In some embodiments, the microgrooves are formed as multiple lines, as shown in Figures 9 and 10. Microgrooves 1600, 1700 are described using similar reference numbers. For example, microgrooves 1600, 1700 comprise side walls 1610, 1710 and floor portions 1620, 1720. As discussed above, each microgroove is recessed in the shaft 140 by multiple side walls (or "side walls") and floor portions. The side walls define the shape of the microgroove.

[0087] Each microgroove defines a shape that may be the same as or different from the remaining microgrooves. Microgrooves may be circles, lines, triangles, squares, rectangles, polygons, or any combination of any suitable shape. Microgrooves may intersect or overlap, or they may be discrete shapes. Microgrooves may form as multiple rows or as groups.

[0088] A group of microgrooves is defined by a collection of dense microgrooves. These groups of microgrooves can be spaced equally apart or with varying spacing. Furthermore, the microgrooves within each group can be spaced equally apart or with varying spacing. The spacing and density of microgrooves within each group and across all groups can be selected so that the microgrooves provide greater perpendicular or torsional resistance to certain parts of the shaft 140.

[0089] Similar to groups of microgrooves, microgrooves can be organized as several rows. Rows of microgrooves can be spaced equally apart or with varying spacing. Furthermore, microgrooves within each row can be spaced equally apart or with varying spacing. The spacing and density of microgrooves within each row, and across all rows, can be selected so that the microgrooves can provide greater vertical or torsional resistance to some portion of the shaft 140. Each microgroove can have a shape that may be the same as or different from adjacent microgrooves in the same row. Furthermore, microgrooves can have the same shape in each row, or different shapes across multiple rows.

[0090] In some embodiments, the microgrooves 1600 can be formed as groups 1630, as shown in Figure 9. The groups 1630 have a hexagonal shape. Each group 1630 comprises six triangular microgrooves 1600.

[0091] In other embodiments, as shown in Figure 10, the microgrooves 1700 can be formed as several rows 1740 extending circumferentially around the shaft 140. The microgrooves 1700 are triangular in shape. The microgrooves 1700 have different sizes across the multiple rows 1740, with the top row of microgrooves 1700 being smaller than the bottom row of microgrooves 1700.

[0092] Furthermore, the microgrooves 1600 and 1700 may be circles, lines, triangles, squares, rectangles, polygons, or any combination of any suitable shapes. The side walls 1610 and 1710 may be oriented non-parallel to or non-perpendicular to the longitudinal axis 110. Thus, each microgroove 1600 and 1700 forms at least one of either a vertical resistance component or a torsional resistance component. Each group and row 1630 and 1740 may be oriented perpendicular to the longitudinal axis 110 or not perpendicular to the longitudinal axis 110. Each group and row 1630 and 1740 may comprise at least one microgroove 1600 and 1700. For example, each group and row 1630 and 1740 may comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more microgrooves 1600 and 1700. Furthermore, one or more groups or rows 1630 and 1740 may be present. For example, there may be one, two, three, four, five, or six or more groups 1630 and rows 1740. The groups and rows 1630 and 1740 can be spaced equally apart or the spacing can be varied. The spacing and density of the microgrooves 1600 and 1700 can be selected to provide greater perpendicular or torsional resistance to some portion of the shaft 140.

[0093] A golf club shaft 140 incorporating microgrooves as described herein offers advantages over shafts known in the art. Mainly, the microgrooves create a stronger joint between the club head and the shaft by (1) allowing epoxy to flow uniformly around the shaft tip, (2) increasing the total effective bonding area, and (3) providing resistance to normal and torsional forces. When a conventional shaft is pressed into a hosel, the epoxy spreads unevenly around the shaft and concentrates near the bottom of the hosel. As a result, pressure can build up within the hosel, creating trapped air pockets within the epoxy. These trapped air pockets can be observed by cutting open the hosel and examining the cross-section after the shaft has been bonded. Trapped air pockets can also be observed by creating a test hosel made of a transparent material (not used in actual clubs), such as plastic, so that the inside of the hosel can be seen during shaft insertion. Trapped air pockets weaken the bond strength and become points of stress fracture propagation. Microgrooves provide pathways for epoxy to flow uniformly around the shaft, thereby reducing pressure buildup within the hosel and significantly decreasing, or even eliminating, the porosity of air pockets. Furthermore, because less epoxy is needed to create a uniform distribution, microgrooves reduce epoxy waste. The sidewalls of the microgrooves provide additional surface area for the epoxy, forming microlinks between the shaft tip and the inner surface of the hosel hole. Additionally, the sidewalls are oriented at least asymmetrically or perpendicularly to the longitudinal axis to resist forces applied parallel or perpendicular to the longitudinal axis. By increasing the bond strength, club designers can add weight components such as tip weights to the hosel. Microgrooves compensate for the reduction in bond strength caused by loss of shaft insertion depth. Furthermore, microgrooves are a versatile mechanism that can accommodate both right-handed and left-handed clubs.

[0094] B. Golf clubs equipped with weighted ferrules This specification further describes various embodiments of weighted ferrules that replace conventional tip weights by removing the mass from the tip weight and redistributing that mass to the ferrule. By removing the mass from the tip weight, the tip weight can be completely removed or its size can be significantly reduced. By removing the tip weight or reducing the tip weight size, the shaft 140 can be inserted deeper into the hosel hole 124, thereby increasing the effective bonding area 154 and improving the bonding strength. The tip weight 190 has a tip weight depth 192 that reduces the allowable shaft insertion depth 152 (and effective bonding depth 156), as shown in Figure 2B. The tip weight depth 192 may range from 0.1 inches to 0.5 inches. For example, the tip weight depth 192 may be 0.1 inches, 0.2 inches, 0.25 inches, 0.3 inches, 0.35 inches, 0.40 inches, or 0.5 inches. In some embodiments, the tip weight 190 is used to manipulate the center of gravity (CG) of the club head 100 or to adjust the swing weight of the club head 100.

[0095] Therefore, in the embodiments discussed below, the tip weight 190 can be removed or replaced with a smaller tip weight 190, which increases the shaft insertion depth 152. In some embodiments, the shaft insertion depth is increased by an amount between 0.10 inches and 0.50 inches. The increase in shaft insertion depth 152 increases the effective bonding area 154, thereby increasing the bonding strength at the head-shaft connection.

[0096] In some embodiments, referring to Figures 11-14, the golf club further comprises a ferrule 2000 positioned around the outer surface 146 of the shaft. The bottom end 142 of the shaft extends into the club head 120 through the ferrule 2000. The ferrule 2000 centers the shaft 140 within the hosel 122 and covers the non-sharp hosel top rim, creating a smooth transition from the hosel 122 to the shaft 140. Referring to Figure 11, the ferrule 2000 is a cylindrical body comprising a top rim 2010 proximal to the grip 160 and a bottom rim 2012 proximal to the club head 120. The ferrule further comprises an inner surface 2014 in contact with the shaft 140 and an outer surface 2016 exposed to the outside. The ferrule 2000 further comprises a ferrule ledge 2018 defining the transition between the upper and lower portions of the ferrule. The upper portion is a tapered region 2020 exposed above the hosel 122. The lower portion is a centering region 2040 located within the hosel 122.

[0097] The centering region 2040 is defined between the ferrule ledge 2018 and the bottom edge 2012. The centering region 2040 is received within the hosel 122 such that the ferrule ledge 2018 is flush with the hole top rim. The centering region 2040 comprises a plurality of windows 2042 and a plurality of ribs 2044. The plurality of windows 2042 increase the paths for excess epoxy to flow around the centering region 2040, thereby increasing the joint strength. The plurality of ribs 2044 act as a self-aligning mechanism. The ribs 2044 are spaced equally apart across the entire centering region 2040, applying an equal amount of pressure to the hosel hole 124, preventing the shaft 140 from entering the hosel 122 at an angle. The centering region 2040 is the lower portion of the ferrule 2000 that is received within the hosel 122, and the tapered region 2020 is the upper portion that is exposed above the hosel 122.

[0098] The tapered region 2020 is defined between the ferrule ledge 2018 and the apex 2010. The tapered region 2020 tapers from the maximum outer diameter 2060 to a smaller diameter near the apex 2010. The tapered region 2020 creates a smooth transition from the shaft diameter 140 to the hosel diameter 122. In some embodiments, the tapered region 2040 accommodates a weight element.

[0099] Ferrule 2000 has a viscosity of 0.9 g / cm³. 3 ~1.5g / cm 3 It is formed from a resin that can have a density of 0.9 g / cm³. In some embodiments, the density is 0.9 g / cm³. 3 ~1.0g / cm 3 1.0 g / cm³ 3 ~1.1 g / cm³ 3 , 1.1 g / cm³ 3 ~1.2g / cm 3 , 1.2 g / cm³ 3 ~1.3g / cm 3 1.3 g / cm³ 3 ~1.4g / cm 3 , or 1.4 g / cm³ 3 ~1.5g / cm 3 It is between these two values. For example, in one embodiment, the resin is 1.19 g / cm³. 3 It can have a density of . In some embodiments, the resin includes cellulose acetate propionate (CAP) resin. The ferrule material is lightweight and does not provide a means of adding weight to the golf club head 120. Therefore, in some embodiments, the ferrule 2000 further comprises a weight element. Various embodiments of the weight element are described below. In some embodiments, the weight element comprises a weight. In other embodiments, the weight element comprises a ferrule formed from a high-density material.

[0100] The various embodiments of the weight elements described below are formed from metallic materials such as stainless steel, tungsten, tungsten-tenite propionate (TPU) mixtures, or stainless steel-tenite propionate (TPU) mixtures. The weight element material is denser than the ferrule material. The density of the weight element material is 1 g / cm³. 3 ~18g / cm 3 It is between 1 g / cm³. In some embodiments, the density of the material of the weight element is 1 g / cm³. 3 ~2g / cm 3 , 2g / cm³ 3 ~3g / cm 3 , 3g / cm³ 3 ~4g / cm 3 , 4g / cm³ 3 ~5g / cm 3 , 5g / cm 3 ~6g / cm 3 , 6g / cm 3 ~7g / cm 3 7g / cm³ 3 ~8g / cm 3 8g / cm³ 3 ~9g / cm 3 , 9g / cm³ 3 ~10g / cm 3 , 10g / cm 3 ~11g / cm 3 , 11 g / cm³ 3 ~12g / cm 3 , 12g / cm³ 3 ~13g / cm 3 13g / cm³ 3 ~14g / cm 3 14g / cm³ 3 ~15g / cm 3 15g / cm³ 3 ~16g / cm 3 , 16g / cm³ 3 ~17g / cm 3 , or 17g / cm³ 3 ~18g / cm 3 It is between these two points.

[0101] The various embodiments of the weight element described below define a height measured along the longitudinal axis 110. The height is measured between the top edge and the bottom edge of the weight element. In some embodiments, the height is between 0.3 inches and 0.7 inches. In some embodiments, the height is between 0.3 inches and 0.45 inches, 0.35 inches and 0.40 inches, 0.40 inches and 0.60 inches, 0.45 inches and 0.60 inches, 0.50 inches and 0.55 inches, 0.52 inches and 0.57 inches, 0.53 inches and 0.60 inches, or 0.54 inches and 0.60 inches. In some embodiments, the height is approximately 0.3 inches, 0.31 inches, 0.32 inches, 0.33 inches, 0.34 inches, 0.35 inches, 0.36 inches, 0.37 inches, 0.38 inches, 0.39 inches, 0.40 inches, 0.41 inches, 0.42 inches, 0.43 inches, 0.44 inches, 0.45 inches, 0.46 inches, 0.47 inches, 0.48 inches, 0.49 inches. These are inches, 0.5 inches, 0.51 inches, 0.52 inches, 0.53 inches, 0.54 inches, 0.55 inches, 0.56 inches, 0.57 inches, 0.58 inches, 0.59 inches, 0.6 inches, 0.61 inches, 0.62 inches, 0.63 inches, 0.64 inches, 0.65 inches, 0.66 inches, 0.67 inches, 0.68 inches, 0.69 inches, or 0.7 inches.

[0102] The various embodiments of the weight element described below further define the thickness measured between the inner and outer surfaces of the weight element. In some embodiments, the thickness remains constant throughout the weight element, while in other embodiments, the thickness varies throughout the weight element. The thickness is between 0.01 inches and 0.09 inches. In some embodiments, the thickness is between 0.01 inches and 0.05 inches, 0.01 inches and 0.07 inches, 0.03 inches and 0.08 inches, 0.04 inches and 0.09 inches, or 0.05 inches and 0.09 inches. In some embodiments, the thickness is approximately 0.01 inches, 0.02 inches, 0.03 inches, 0.04 inches, 0.05 inches, 0.06 inches, 0.07 inches, 0.08 inches, or 0.09 inches. In one exemplary embodiment, the thickness near the top edge is 0.031 inches, and the thickness near the bottom edge is 0.062 inches. In another exemplary embodiment, the thickness near the top edge is 0.021 inches, and the thickness near the bottom edge is 0.055 inches.

[0103] The ferrule 2000, comprising a weight element and resin material, defines a mass between 1 gram and 12 grams. In some embodiments, the mass is between 1 gram and 5 grams, 2 grams and 7 grams, 3 grams and 6 grams, 5 grams and 10 grams, or 6 grams and 12 grams. In other embodiments, the mass is 1 gram, 2 grams, 3 grams, 4 grams, 5 grams, 6 grams, 7 grams, 8 grams, 9 grams, 10 grams, 11 grams, or 12 grams. The mass of the ferrule 2000 is selected to provide a substantial weight element to the club head for manipulating the club head CG and / or achieving a desired swing weight.

[0104] The ferrule 2000, which includes weight elements and resin material, has a weight of 1 g / cm³. 3 ~6g / cm 3 The average density in this range is further defined as the ratio of the total mass of the ferrule 2000 to the total volume of the ferrule 2000. For example, the average density is 2.95 g / cm³. 3This may be the case. In other embodiments, the ferrule 2000 is 1 g / cm³ 3 1.5 g / cm³ 3 , 2g / cm³ 3 2.5 g / cm³ 3 , 3g / cm³ 3 3.5 g / cm³ 3 , 4g / cm³ 3 4.5 g / cm³ 3 , 5g / cm 3 5.5 g / cm³ 3 , or 6 g / cm³ 3 It can have an average density that is possible.

[0105] A ferrule 2000 comprising a weight element and resin material has a mass increase rate of 300% to 2500% compared to a ferrule comprising only resin material. In some embodiments, the mass increase rates are 300% to 400%, 400% to 500%, 500% to 600%, 600% to 700%, 700% to 800%, 800% to 900%, 900% to 1000%, 1000% to 1100%, 1100% to 1200%, 1200% to 1300%, 1300% to 1400%, and 1 The ranges are between 400% and 1500%, 1500% and 1600%, 1600% and 1700%, 1700% and 1800%, 1800% and 1900%, 1900% and 2000%, 2000% and 2100%, 2100% and 2200%, 2200% and 2300%, 2300% and 2400%, or between 2400% and 2500%.

[0106] The weight element may be an internal weight positioned between the inner surface of the ferrule and the shaft, a weight ring extending circumferentially around the outer surface of the ferrule, or a ferrule made of high-density material. The weight element replaces the conventional tip weight by removing the mass from the tip weight and redistributing that mass to the ferrule. By removing the mass from the tip weight, the tip weight can be completely removed or its size can be significantly reduced. By removing the tip weight or reducing its size, the shaft 140 can be inserted deeper into the hosel hole 124, thereby increasing the effective bonding area 154 and improving the bonding strength.

[0107] I. Ferrule with internal weight In one embodiment (see Figure 12A), the ferrule 2000 includes an internal weight 2100. The internal weight 2100 provides substantial mass to the ferrule 2000, manipulating the club head CG and forming a weight element that can serve as a substitute for a tip weight. Referring to Figure 12A, the internal weight 2100 is formed integrally with the ferrule 2000 near the tapered region 2020. The internal weight 2010 extends through the entire tapered region 2020. However, in other embodiments, the internal weight 2100 extends through only a portion of the tapered region 2020.

[0108] Referring to Figure 12B, the internal weight 2100 is cylindrical and comprises a top edge 2110 proximal to the ferrule top edge 2010 and a bottom edge 2120 proximal to the ferrule bottom edge 2012. The internal weight 2100 further comprises an inner surface 2130 that forms part of the inner surface 2014 of the ferrule and an outer surface 2140 that contacts the ferrule 2000. The internal weight 2100 defines a gap 2150 extending from the top edge 2110 to the bottom edge 2120. When the ferrule 2000 is pressed onto the shaft 140, the gap 2150 relieves stress throughout the ferrule 2000.

[0109] Gap 2150 defines the gap width measured across the opening. The gap width ranges from 0.01 inches to 0.5 inches. In some embodiments, the gap width is 0.01 inches to 0.05 inches, 0.02 inches to 0.04 inches, 0.03 inches to 0.07 inches, 0.04 inches to 0.09 inches, 0.05 inches to 0.10 inches, 0.10 inches to 0.25 inches, 0.15 inches to 0.45 inches, 0.20 inches to 0.40 inches, 0.25 inches to 0.50 inches, 0.30 inches to 0.5 inches, or 0.40 inches to 0.50 inches. The gap width is approximately 0.01 inches, 0.02 inches, 0.03 inches, 0.04 inches, 0.05 inches, 0.06 inches, 0.07 inches, 0.08 inches, 0.09 inches, 0.10 inches, 0.15 inches, 0.20 inches, 0.25 inches, 0.30 inches, 0.35 inches, 0.40 inches, 0.45 inches, or 0.50 inches. In one exemplary embodiment, the gap width is 0.03 inches. The gap width is selected to provide stress relief to the ferrule 2000 without significantly reducing the mass of the internal weight 2100. The dimensions of the internal weight are further selected to provide a substantial weight-adding function.

[0110] The internal weight 2100 defines a height between 0.5 inches and 0.6 inches. In some embodiments, the height is between 0.50 inches and 0.55 inches, 0.52 inches and 0.57 inches, 0.53 inches and 0.60 inches, or 0.54 inches and 0.60 inches. The height is approximately 0.5 inches, 0.51 inches, 0.52 inches, 0.53 inches, 0.54 inches, 0.55 inches, 0.56 inches, 0.57 inches, 0.58 inches, 0.59 inches, 0.6 inches, 0.61 inches, 0.62 inches, 0.63 inches, 0.64 inches, 0.65 inches, 0.66 inches, 0.67 inches, 0.68 inches, 0.69 inches, or 0.7 inches. In one exemplary embodiment, the height is 0.653 inches. The internal weight 2100 is concealed within the ferrule 2000 and is not exposed to the outer surface 2016 of the ferrule. In other embodiments, the weight element is exposed to the outer surface 2016 of the ferrule.

[0111] II. Ferrule with weight ring Referring to Figures 13A-14, in some embodiments, the ferrule 2000 may comprise one or more weighted rings. The weighted rings provide substantial mass to the ferrule 2000, manipulating the club head CG and forming a weight element that can serve as a substitute for a tip weight. The weighted rings are formed integrally with the ferrule 2000 and extend circumferentially around the tapered region 2020. The weighted rings may consist of one, two, three, four, five, or any other suitable number of rings. In some embodiments, the weighted rings have the same height, while in other embodiments, the weighted rings have different heights.

[0112] Referring to Figures 13A and 13B, the ferrule 2000 further comprises a single weighted ring 2200. The weighted ring 2200 comprises a top edge 2210 proximal to the top edge 2010 of the ferrule and a bottom edge 2220 proximal to the bottom edge 2012 of the ferrule. The weighted ring 2200 further comprises an inner surface 2230 adjacent to the outer surface 2016 of the ferrule and an outer surface forming a portion of the outer surface 2016 of the ferrule.

[0113] Referring to Figure 14, the ferrule 2000 further comprises two load rings 2300. Each load ring 2300 comprises a top edge 2310 proximal to the top edge 2010 of the ferrule and a bottom edge 2320 proximal to the bottom edge 2012 of the ferrule. Each load ring 2300 further comprises an inner surface 2330 adjacent to the outer surface 2016 of the ferrule and an outer surface forming a portion of the outer surface 2016 of the ferrule.

[0114] III. Ferrules formed from high-density materials In another embodiment, the weight mechanism comprises a high-density ferrule similar to the ferrule disclosed in the previous embodiment. The ferrule can be molded from a high-density resin mixture such that the ferrule 2000 has a suitable mass to replace the tip weight. The resin mixture may include a combination of resin and filler material. In some embodiments, the resin may include cellulose acetate propionate (CAP) resin. The filler material may be selected from the group consisting of steel or tungsten. The resin mixture may have a specific gravity of 1 to 9. In some embodiments, the specific gravity may be between 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, 7 to 8, 8 to 9, or 9 to 10.

[0115] The overall mass of a high-density ferrule can range from 0.1 grams to 20 grams. For example, high-density ferrules can range from 0.1 to 2 grams, 2 to 4 grams, 4 to 6 grams, 6 to 8 grams, 8 to 10 grams, 10 to 12 grams, 12 to 14 grams, 14 to 16 grams, 16 to 18 grams, and 18 to 20 grams. The mass of the ferrule can be selected to provide a substantial weight element.

[0116] The weighted ferrule described herein is designed to replace the tip weight 190, thereby allowing the shaft 140 to be inserted deeper into the hosel hole 124. The increased shaft insertion depth 152 increases the effective contact area 154, thereby increasing the joint strength at the head-shaft connection. Furthermore, the ferrule 2000 with the weight element described above improves mass properties such as MOI and CG. The ferrule 2000 is located above the hosel 122 and closer to the periphery of the club head 100 than the tip weight 190. Thus, the ferrule 2000 shifts the mass closer to the periphery of the club head 100, thereby improving the moment of inertia (MOI) of the club head 100.

[0117] C. Golf club head with hot melt weight This specification further describes another embodiment that provides an alternative means for adding weight to a shaft, similar to the embodiment of the weighted ferrule described above. In this embodiment, a hot-melt weight is injected into the tip of the shaft, increasing the overall weight of the shaft by the added mass. As described above, adding weight to the shaft allows for an increase in the overall shaft insertion depth by removing or reducing the size of the tip weight.

[0118] In one embodiment, the club head 100 may include a ferrule 2000, similar to the embodiments described above. The shaft 140 may further include a hot melt weight 3000 and a cap 3050, as shown in Figures 15A and 15B. The hot melt weight 3000 may be formed inside the shaft 140 along the longitudinal axis 110. The hot melt weight 3000 may be located within the hosel hole 124 near the shaft bottom end 144. The cap 3050 may be located near the bottom end 144 to secure the hot melt weight 3000 inside the shaft 140. In some embodiments, the hot melt weight 3000 may extend from the shaft bottom end 144 to the bottom edge 2012 of the ferrule. In other embodiments, the hot melt weight may extend from the bottom end 144 to the top edge of the ferrule. The hot melt weight 3000 can extend from the bottom end 144 to any suitable length within the shaft 140 to form the desired mass.

[0119] The hot melt weight 3000 can be made from a partially thermoplastic polymer. For example, the hot melt weight can be made from butyl rubber (BR), hydrocarbon resin, polybutene, process oil, or any combination thereof. In some embodiments, the hot melt weight 3000 contains 30% BR, 50% hydrocarbon resin, 15% polybutene, and 5% process oil. The hot melt is solid at room temperature but can become liquid when activated by a heating element. The hot melt weight 3000 is liquid when injected into the tip of the shaft and becomes solid when cooled. The hot melt weight 3000 bonds to the inner surface of the shaft and prevents the hot melt weight 3000 from moving within the shaft.

[0120] Hot melt weight 3000 can be formed in part from metal filler material. The metal filler material can form part of the composition of the hot melt described above. The metal filler material can include any suitable high-density material, such as tungsten powder. The metal filler material increases the overall density of the hot melt weight 3000, achieving a weight sufficient to replace the chip weight 190. The metal filler material can add any amount of weight with an accuracy of 0.1 grams.

[0121] A hot melt weight of 3000 can range from 0.1 grams to 20 grams. For example, a hot melt weight of 3000 can range from 0.1 to 2 grams, 2 to 4 grams, 4 to 6 grams, 6 to 8 grams, 8 to 10 grams, 10 to 12 grams, 12 to 14 grams, 14 to 16 grams, 16 to 18 grams, or 18 to 20 grams.

[0122] The weighting mechanisms described herein offer several advantages over conventional perimeter weights. Removing the tip weight allows the shaft to engage further into the hosel, increasing the surface area for bonding and reducing the amount of clubhead breakage in practice. Furthermore, removing the tip weight eliminates vibration or rattle caused by a loose tip weight. These weighting mechanisms shift mass closer to the periphery than conventional tip weights, increasing the MOI and creating a more forgiving club. The filler material used to form the weight allows for the addition of any amount of weight with high precision.

[0123] method The golf club 100 described herein can be manufactured in various ways. As discussed above, the golf club 100 comprises at least a club head, a shaft, and a grip. By combining different embodiments of each mechanism, numerous variations of the golf club 100 can be formed. The shaft may comprise any one or more of the variations of the microgrooves 1000, 1100, 1200, 1300, 1400, or 1500 described above. The manufacturing method may differ for each different variation of the golf club 100. An exemplary method for manufacturing the golf club 100 is described below.

[0124] A method for manufacturing a club head 100 having microgrooves 1000, 1100, 1200, 1300, 1400, 1500 may include (1) forming a shaft 140, (2) etching microgrooves 1000, 1100, 1200, 1300, 1400, 1500 onto the shaft, (3) injecting epoxy material into a hosel hole 124 and inserting the shaft 140 into the hosel hole 124, and (4) injecting epoxy material into a grip and inserting the shaft 140 into the grip. In step 1, the shaft 140 may be a graphite shaft or a steel shaft. The shaft is formed by bending a sheet of prepreg around a steel mandrel, coating the prepreg material with resin, curing the shaft 140, and removing the steel mandrel. In step 2, the shaft 140 can be rotated using a shaft spinner, which allows the microgrooves 1000, 1100, 1200, 1300, 1400, and 1500 of any modified form to be applied to the shaft. The application of the microgrooves 1000, 1100, 1200, 1300, 1400, and 1500 may depend on the shaft material used. For example, a 3D printer can be used to etch the microgrooves 1000, 1100, 1200, 1300, 1400, and 1500 into the outer resin layer. In step 3, the microgrooves 1000, 1100, 1200, 1300, 1400, and 1500 formed near the tip of the shaft allow the epoxy to flow uniformly around the tip of the shaft, which reduces pressure buildup and air pockets within the hosel.

[0125] A method for manufacturing a club head 100 equipped with a ferrule 2000 may include the steps of: (1) forming weight mechanisms 2100, 2200, and 2300 from a first material; (2) forming the ferrule 2000 integrally with the weight mechanisms 2100, 2200, and 2300 using a second material; (3) inserting the shaft 140 into the ferrule 2000; (4) securing the shaft 140 and the ferrule 2000 to the hosel 122; (5) blending the ferrule 2000; and (6) assembling the toe weight. In step 1, the first material may include a metal consisting of stainless steel, tungsten, a tungsten-tenite propionate (TPU) mixture, or a stainless steel-tenite propionate (TPU) mixture. In step 2, the ferrule 2000 may be injection molded around the weight mechanisms 2100, 2200, and 2300. The second material may include a resin. In some embodiments, the resin may consist of a cellulose acetate propionate (CAP) resin. In step 3, in some embodiments, the shaft 140 can be inserted into the ferrule 2000 so that the gap 2150 relieves stress. In step 4, epoxy can be used to secure the shaft within the hosel 122. Multiple ribs 2024 located in the ferrule 2000 help to center the shaft 140 within the hosel 122 by applying circumferential pressure to the hosel hole 124. Multiple windows 2042 located in the ferrule 2000 allow excess epoxy to flow around the ferrule 2000, increasing the bond strength between the shaft 140 and the hosel 122. In step 5, the ferrule 2000 can be blended with acetone so that it can be made flush with the hole top rim 126. In step 6, a toe weight can be secured using a screw.

[0126] A method for manufacturing a club head 100 with a high-density ferrule (not shown) may include the steps of: (1) forming a ferrule from a high-density resin mixture; (2) inserting a shaft 140 into the ferrule; (3) securing the shaft 140 and ferrule to a hosel 122; (4) blending the ferrule; and (5) assembling a toe weight. In step 1, the ferrule may be injection molded. The resin mixture may include a combination of resin and filler material. In some embodiments, the resin may include cellulose acetate propionate (CAP) resin, and the filler material may be steel or tungsten. In step 3, epoxy may be used to secure the shaft 140 within the hosel 122. Multiple ribs 2044 located on the ferrule 2000 help to center the shaft 140 within the hosel 122 by applying circumferential pressure to the hosel hole 124. Multiple windows 2042 located in the ferrule 2000 allow excess epoxy to flow around the ferrule 2000, increasing the bond strength between the shaft 140 and the hosel 122. In step 4, the ferrule 2000 can be blended with acetone so that it can be made flush with the hosel hole rim 126. In step 4, the toe weight can be secured using screws.

[0127] A method for manufacturing a club head 100 equipped with a hot melt weight 3000 may include: (1) forming a hot melt weight using a first material; (2) securing a cap 3050 to the shaft bottom end 144; (3) curing the hot melt weight 3000; (4) forming a ferrule 2000 using a second material; (5) inserting the shaft 140 into the ferrule 2000; (6) securing the shaft 140 and the ferrule 2000 to the hosel 122; (7) blending the ferrule 2000; and (8) assembling a toe weight. In step 1, the hot melt weight 3000 can be formed near the shaft bottom end 144. The first material, or hot melt solution, may include a metal and a filler material. In some embodiments, the filler material may include tungsten powder. In step 2, the cap 3050 may be equipped with a centering cap or Christmas tree plug that can be press-fitted onto the shaft bottom end 144. The cap 3050 can prevent the hot melt solution from leaking out of the shaft 140. In step 3, the golf club can be positioned in the curing carousel so that the hot melt weight 3000 can be positioned near the shaft bottom end 144. In step 4, the ferrule 2000 can be injection molded. In some embodiments, the second material may include a resin. In other embodiments, the second material may include a resin mixture comprising a combination of resin and a filler material. In some embodiments, the resin may include cellulose acetate propionate (CAP) resin, and the filler material may be steel or tungsten. In step 6, the shaft 140 can be fixed in the hosel 122 using epoxy. Multiple ribs 2044 located on the ferrule 2000 help to center the shaft 140 in the hosel 122 by applying circumferential pressure to the hosel hole 124.Multiple windows 2042 located in the ferrule 2000 allow excess epoxy to flow around the ferrule 2000, increasing the bond strength between the shaft 140 and the hosel 122. In step 7, the ferrule 2000 can be blended with acetone so that it can be made flush with the hosel hole rim 126. In step 8, the toe weight can be secured using screws. [Examples]

[0128] A. Example A: Microgroove tensile test Tensile tests were conducted to demonstrate the effect of microgrooves on epoxy tensile strength. In these tensile tests, various shafts were used to measure the normal force required before the head-shaft connection broke. Each shaft was formed with or without microgrooves, and the shaft insertion depth was varied. For each sample shaft, the effective joint depth was equal to the shaft insertion depth. The purpose of these tensile tests was to investigate how much additional strength could be obtained by adding microgrooves and increasing the shaft insertion depth.

[0129] The first sample shaft was a control shaft without microgrooves and with a shaft insertion depth of 1.1 inches. The tip of the control shaft was prepared using the sanding method currently used to manufacture the shaft. The second shaft was a first exemplary shaft having microgrooves similar to those shown in Figures 3A and 3B. The first exemplary shaft had a shaft insertion depth of 1.1 inches. The third shaft was also a second exemplary shaft having microgrooves similar to those shown in Figures 3A and 3B. The second exemplary shaft had an FSD of 1.3 inches and contained microgrooves. The microgrooves of the first and second exemplary shafts were similar, but the shaft insertion depth was varied. The microgrooves included a first and second set of interconnected microgrooves applied to the entire shaft joint region.

[0130] Tensile tests were performed by fixing the club and pulling the shaft away from the club head. Three sample shafts were tested five times each, ending each test when the epoxy bond explosively failed (indicating failure when the club head flew off). The tensile tests measured the force at which the connection failed at a specific displacement. This force represents the strength of the head-shaft connection. This test measured the average strength of each of the five tensile tests and the minimum strength for each sample shaft. In each test, the same amount of epoxy was used on each sample shaft, and the depth and pattern of the microgrooves were kept constant for the exemplary shafts. [Table 1]

[0131] The results of this tensile test are shown in Table 1 above. This tensile test concluded that shafts with microgrooves exhibited higher epoxy tensile strength. The average epoxy tensile strength of the control shaft was 2756.77 lbf, with a standard deviation of 151.14 lbf. The minimum epoxy tensile strength of the control shaft was 2589.37 lbf.

[0132] The average epoxy tensile strength of the first exemplary shaft was 3269.15 lbf, with a standard deviation of 102.27 lbf. The average epoxy tensile strength of the first exemplary shaft was 18.59% (512.38 lbf) higher than that of the control shaft. The minimum epoxy tensile strength of the first exemplary shaft was 3153.92 lbf, a 21.80% increase compared to the control shaft. The control shaft and the first exemplary shaft had the same shaft insertion depth, but the first exemplary shaft had a larger effective bonding area due to the presence of microgrooves. The first exemplary shaft demonstrated the additional strength of the shaft when microgrooves were added while maintaining a constant shaft insertion depth.

[0133] The mean epoxy tensile strength of the second exemplary shaft was 3470.13 lbf, with a standard deviation of 174.21 lbf. The mean epoxy tensile strength of the second exemplary shaft increased by 25.88% (713.36 lbf) compared to the control test. The minimum epoxy tensile strength of the second exemplary shaft was 3292.90 lbf, an increase of 27.17%. The second exemplary shaft had a deeper shaft insertion depth than both the control shaft and the first exemplary shaft. By increasing the shaft insertion depth from 1.1 inches to 1.3 inches, the mean epoxy tensile strength of the second exemplary shaft increased by 200.98 lbf compared to the first exemplary shaft. The second exemplary shaft demonstrated additional shaft strength when the shaft insertion depth was increased. The tensile tests concluded that introducing microgrooves into the shaft and increasing the shaft insertion depth significantly increased the bond strength between the club head and the shaft.

[0134] B. Example B: Microgroove Tensile Test (Comparison of Hosel and Microgroove) A tensile test similar to the one in Example A was performed to demonstrate the effect of microgroove depth and to compare the bonding strength between microgrooves located in the hosel and those located in the shaft. This tensile test determines the maximum force that the club head / shaft connection can withstand before it breaks. A higher force indicates a stronger connection. In this tensile test, two exemplary club heads from one embodiment were compared with a control club head.

[0135] The comparison club head comprised a club head body, a hosel, and a shaft. The shaft did not have microgrooves. The hosel had microgrooves on the inner surface of the hosel hole. The grooves extended perpendicular to the longitudinal axis 110. The grooves were parallel and spaced equally apart so as not to intersect. Furthermore, the grooves had a depth of 0.003 inches. The groove depth did not compromise shaft durability.

[0136] The first exemplary club head had a shaft with horizontal microgrooves, as shown in Figure 4. The shaft had four parallel microgrooves spaced equally apart so as not to intersect. The microgrooves had a depth of 0.002 inches.

[0137] The second sample, like the first sample, had a shaft with horizontal microgrooves, as shown in Figure 4. The shaft had four parallel microgrooves spaced equally apart so as not to intersect. The microgrooves had a depth of 0.006 inches. [Table 2]

[0138] The results of this tensile test are shown in Table 3 above. This tensile test concluded that club heads with microgrooves in the shaft have higher joint strength than club heads with microgrooves in the hosel. Furthermore, this test concluded that deeper microgrooves result in higher joint strength than shallower microgrooves.

[0139] The first example club head had a joint strength of 2198.60 lbf, an increase of 163.62 lbf (8%) compared to the control club head. Therefore, the shaft with microgrooves has superior joint strength compared to the hosel with microgrooves.

[0140] The second exemplary club head had a bond strength of 2308.91 lbf, an increase of 273.93 lbf (13.4%) compared to the control club head. Furthermore, the second exemplary club head was 110.31 lbf stronger than the first exemplary club head. Increasing the groove depth from 0.002 inches to 0.006 inches increased the bond strength.

[0141] C. Example C: Ferrule extreme temperature test Extreme temperature (ET) testing was conducted to evaluate the durability of several ferrules with different weight elements under extreme temperature control conditions. The purpose of this test was to determine how several weighted ferrule designs perform under stress across a wide range of temperatures. In other words, the ET testing demonstrated the flexibility and fracture resistance of the weighted ferrule designs.

[0142] Three different weighted ferrule designs were tested on assembled golf clubs. In each of the three ET tests, one of the ferrule designs was evaluated, and 4-5 sample golf clubs with the same ferrule design were used. Each sample golf club was assembled using the respective weighted ferrule and cured for 24 hours before testing. Each sample was placed in a freezer at approximately 0°F for approximately 2 hours. The temperature of the sample was measured upon removal from the freezer. Then, using this sample, 30 "low-temperature" blows were performed near the lower area of ​​the clubface toe. The temperature of each sample was then obtained after 30 low-temperature blows. Next, the samples were placed in an oven at approximately 200°F for approximately 2 hours. The temperature of the test sample was obtained upon removal from the oven. Again, using this sample, 30 "high-temperature" blows were performed near the lower area of ​​the clubface toe. The temperature of each sample was then obtained after 30 high-temperature blows. For each sample, it was determined whether it passed or failed the ET test. Failed samples show signs of wear, such as cracks, breakage, chipping, and twisting. In contrast, approved samples show no signs of wear.

[0143] Each sample was an iron-type golf club. The material of the weighted ferrule was kept constant throughout the three tests. Each sample contained a ferrule formed from CAP resin, which is used to form conventional ferrules. Each sample further contained an internal weight made of steel. The three tests evaluated ferrules with internal weights of different masses and dimensions. Throughout the tests, the dimensions of the internal weight, such as outer diameter and height, were adjusted to balance the mass and volume of the internal weight material with the ferrule body material. The balance of materials affects the strength and flexibility of the ferrule. Another important dimension is the curvature of the internal weight edge. The internal weight includes an upper and lower edge, each with curvature. The curvature was adjusted throughout the tests to reduce stress points throughout the ferrule.

[0144] Test 1: Five test samples were used in the first ET test. The mass of the internal weight was 3.69 grams, and the mass of the assembled ferrule was 4.54 grams. The curvature of the edge was 0.1 inches. The results of the first ET are shown in Table 1 below. Each sample passed in the first 30 shots but failed in the next 30 shots. The pass rate for the first test was 0%. [Table 3]

[0145] Second Test: The second ET test also used five test samples. The internal weight mass was 3.80 grams, and the assembled ferrule mass was 4.60 grams. The internal weight height was 0.65 inches, and the outer diameter was 0.490 inches. The internal weight used in the second test contained more rounded corners (greater curvature). Corners can become stress points, and removing them can prevent cracking. The curvature was changed from 0.1 inches to 0.4 inches. The results of the second ET are shown in Table 2 below. In the second test, only two of the samples failed, and three of the five samples passed. The pass rate for the second test was 60%. [Table 4]

[0146] Third Test: Four samples were used in the third ET test. The mass of the internal weight was X grams, and the mass of the assembled ferrule was X grams. Compared to the second test sample, the outer diameter of the internal weight was reduced from 0.490 inches to 0.436 inches, and the length was reduced from 0.65 inches to 0.63 inches. Although the outer diameter was reduced compared to the second test, it was still larger than the outer diameter of the ferrule in the first test. In the third test, a ferrule with more rounded corners than the sample used in the first test was used again. The curvature was reduced from 0.4 inches to 0.3 inches. The results of the third ET are shown in Table 3 below. In the third ET test, all four samples passed. The pass rate in the third test was 100%. [Table 5]

[0147] The results of the three tests demonstrate the effect of internal weight dimensions on durability. These results show that reducing the weight height and diameter improves the ferrule's durability. Furthermore, increasing the curvature of the rounded corners also improves the ferrule's durability. The weight and ferrule geometry used in Test 3 showed a 100% pass rate. Therefore, the weighted ferrule design is durable and can be successfully implemented in products without breakage.

[0148] D. Example D: Example of mass properties of a weighted ferrule A comparative test was conducted between an exemplary club head with a weighted ferrule and a control club head with a ferrule and tip weight. This test was performed to compare the center of gravity position and moment of inertia characteristics. The characteristics of the center of gravity and moment of inertia are defined within the coordinate system and center of gravity coordinate system described above. Computer-aided design software was used to determine the center of gravity position and moment of inertia in this test.

[0149] The exemplary club head comprised a club head, shaft, and weighted ferrule, similar to the embodiments shown in Figures 12A and 12B. The weighted ferrule had a total weight of 7.35 grams. The exemplary club head did not have a tip weight, and therefore the shaft was inserted further into the hosel to improve joint strength.

[0150] The control club head had the same club head geometry as the exemplary club head. The control club head further had a ferrule with a mass of 1.35 grams. The ferrule of the control club head did not have a weight element. The control club head further had a 6-gram tip weight so that the shaft insertion depth was shallower than that of the exemplary embodiment described above. [Table 6]

[0151] The exemplary club head had a CG position along the x-axis. CGx was 0.065 inches. The exemplary club head also had a CG position along the y-axis. CGy was 0.631 inches. The exemplary club head also had an MOI around the x-axis. Ixx was 139.7. The exemplary club head also had an MOI around the y-axis. Iyy was 545.6.

[0152] The control club head had a CG position along the x-axis. CGx was 0.048 inches. The control club head had a CG position along the y-axis. CGy was 0.598 inches. The control club head had an MOI around the x-axis. Ixx was 118.6. The control club head had an MOI around the y-axis. Iyy was 523.

[0153] The exemplary club head had a CGx position that was 0.017 inches further along the x-axis (towards the heel) than the control club head. Furthermore, the exemplary club head had a CGy position that was 0.033 inches further along the y-axis (upwards) than the control club head. The exemplary club head had a 17.8% increase in Ixx compared to the control club head. The exemplary club head had a 4.3% increase in Iyy compared to the control club head.

[0154] Therefore, the exemplary club head with a weighted ferrule showed an increased moment of inertia around both the x and y axes compared to the control club head with a tip weight. This increased moment of inertia gives the exemplary club head an improved performance compared to the control club head. Furthermore, the weighted ferrule further improves the joint strength because the shaft is inserted deeper into the hosel than in the control club head with a tip weight.

[0155] Clause Clause 1: A golf club comprising a club head, a shaft, and a grip, wherein the club head comprises a body and a hosel, the hosel comprising a hosel hole having an inner surface defining a hosel joint region, the shaft comprising a shaft tip, a shaft rear end, and a shaft outer surface, the hosel hole receiving the shaft tip forming a head-shaft connection, the shaft defining a longitudinal axis extending from the geometric center of the shaft rear end to the geometric center of the shaft tip, the shaft outer surface defining a shaft joint region and an effective joint region near the shaft tip, the shaft joint region being the portion of the shaft outer surface inserted into the hosel hole A golf club wherein the effective bonding region is a portion of the outer surface of the shaft that is in contact with the hosel bonding region, the effective bonding region comprises a plurality of microgrooves, the plurality of microgrooves are recessed into the shaft from the outer surface of the shaft via a plurality of side walls, the plurality of side walls increase the effective bonding region, the plurality of microgrooves are formed as a line and define a first plurality of microgrooves extending in a first direction and a second plurality of microgrooves extending in a second direction, the first plurality of microgrooves and the second plurality of microgrooves are interconnected and extend circumferentially around the shaft, and the grip is connected to the rear end of the shaft.

[0156] Clause 2: The golf club according to Clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves are integrally formed with the shaft.

[0157] Clause 3: The golf club as described in Clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves define the individual microgroove depths, and the individual microgroove depths are less than 0.0038 inches.

[0158] Clause 4: The golf club according to Clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves define a total microgroove depth, the total microgroove depth is measured along the longitudinal axis, the total microgroove depth is the depth of the shaft tip having the microgrooves, and the total microgroove depth is between 1.00 inch and 3.00 inch.

[0159] Clause 5: The golf club according to Clause 1, wherein the first plurality of microgrooves and the second plurality of microgrooves cover 50% to 90% of the shaft joint area.

[0160] Clause 6: The golf club according to Clause 1, wherein each of the plurality of microgrooves comprises a base portion, the base portion being perpendicular to the plurality of side walls of the individual microgrooves, and the individual microgrooves being U-shaped in cross-section.

[0161] Clause 7: The golf club according to Clause 1, wherein each microgroove of the first plurality of microgrooves extends in the first direction and is parallel to adjacent microgrooves of the first plurality of microgrooves, and each microgroove of the second plurality of microgrooves extends in the second direction and is parallel to adjacent microgrooves of the second plurality of microgrooves.

[0162] Clause 8: The golf club according to Clause 7, wherein the first and second directions are oblique to the longitudinal axis.

[0163] Clause 9: The golf club as described in Clause 8, wherein the first plurality of microgrooves and the second plurality of microgrooves provide resistance to normal and torsional forces.

[0164] Clause 10: The golf club according to Clause 7, wherein the first direction is perpendicular to the longitudinal axis and the second direction is parallel to the longitudinal axis.

[0165] Clause 11: A golf club comprising a club head, a shaft, and a grip, wherein the club head comprises a body and a hosel, the hosel comprising a hosel hole having an inner surface defining a hosel joint region, the shaft comprising a shaft tip, a shaft rear end, and a shaft outer surface, the hosel hole receiving the shaft tip which forms a head-shaft connection, the shaft defining a longitudinal axis extending from the geometric center of the shaft rear end to the geometric center of the shaft tip, the shaft outer surface defining a shaft joint region and an effective joint region near the shaft tip, A golf club wherein the shaft joining region is the portion of the outer surface of the shaft that is inserted into the hosel hole, the effective joining region is the portion of the outer surface of the shaft that is in contact with the hosel joining region, the effective joining region comprises a plurality of microgrooves, the plurality of microgrooves are recessed into the shaft from the outer surface of the shaft via a plurality of side walls, the plurality of side walls increase the effective joining region, the plurality of microgrooves are formed into a predetermined shape, the plurality of microgrooves are not interconnected, extend circumferentially around the shaft, and the grip is connected to the rear end of the shaft.

[0166] Clause 12: The golf club according to Clause 11, wherein the plurality of microgrooves are formed integrally with the shaft.

[0167] Article 13: The golf club as described in Clause 11, wherein the plurality of microgrooves define the individual microgroove depths, the individual microgroove depths being less than 0.0038 inches.

[0168] Clause 14: The golf club as described in Clause 11, wherein the plurality of microgrooves define a total microgroove depth, the total microgroove depth is measured along the longitudinal axis, the total microgroove depth is the depth of the shaft tip having the microgrooves, and the total microgroove depth is between 1.00 inch and 3.00 inch.

[0169] Clause 15: The golf club according to Clause 11, wherein the plurality of microgrooves cover 50% to 90% of the shaft joint area.

[0170] Clause 16: The golf club according to Clause 11, wherein each of the plurality of microgrooves comprises a base portion, the base portion being perpendicular to the plurality of side walls of the individual microgrooves, and the individual microgrooves being U-shaped in cross-section.

[0171] Clause 17: A golf club as described in Clause 11, wherein each microgroove has a shape selected from the group consisting of triangles, lines, squares, rectangles, or spirals.

[0172] Clause 18: The golf club described in Clause 17, wherein each of the microgrooves has the same shape.

[0173] Clause 19: The golf club described in Clause 17, wherein each of the microgrooves has a different shape.

[0174] Clause 20: The golf club according to Clause 11, wherein the plurality of microgrooves provide resistance to normal and torsional forces.

[0175] Clause 21: A golf club comprising a club head, shaft, grip, and ferrule, wherein the club head comprises a body and a hosel having a hosel rim, a hosel base, and an inner hosel surface, the inner hosel surface defining a hosel hole extending from the hosel rim to the hosel base; the shaft having a top end that is received in the grip, a bottom end that is received in the hosel hole, and a diameter; the ferrule comprising a top edge, a bottom edge, a ledge, an outer surface, an inner surface, a centering region, and a tapered region, the ledge defining a boundary between the tapered region and the centering region, the centering region being the lower portion of the ferrule defined between the ledge and the bottom edge, the centering region being received in the hosel hole, and the tapered region being the upper portion of the ferrule defined between the ledge and the top edge, the tapered region comprising an internal weight, the internal weight comprising a cylindrical tube having a top edge, a bottom edge, an inner surface, an outer surface, and a gap.

[0176] Clause 22: The golf club as described in Clause 21, wherein the internal weight is formed integrally with the tapered region.

[0177] Clause 23: The golf club as described in Clause 21, wherein the inner surface of the internal weight forms part of the inner surface of the ferrule.

[0178] Clause 24: A golf club as described in Clause 21, which defines a gap as an opening extending from the top rim to the bottom rim.

[0179] Clause 25: A golf club as described in Clause 24, having a gap width between 0.01 inches and 0.5 inches.

[0180] Clause 26: A golf club as described in Clause 21, wherein the internal weight has a height between 0.5 inches and 0.7 inches.

[0181] Clause 27: A golf club as described in Clause 21, wherein the internal weight has a thickness between 0.01 inches and 0.09 inches.

[0182] Clause 28: The golf club according to claim 27, wherein the thickness of the internal weight increases from the top periphery to the bottom periphery.

[0183] Clause 29: The golf club as described in Clause 21, wherein the centering region comprises multiple windows for increasing epoxy flow around the shaft to form a stronger bond between the shaft and the hosel.

[0184] Clause 30: The golf club as described in Clause 21, wherein the centering area further comprises a plurality of ribs, the plurality of ribs being equally spaced apart throughout the centering area, and the plurality of ribs applying equal pressure to the hosel hole to center the shaft within the hosel.

[0185] Clause 31: A golf club comprising a club head, a shaft, a grip, and a ferrule, wherein the club head comprises a body and a hosel having a hosel rim, a hosel base, and an inner hosel surface, the inner hosel surface defining a hosel hole extending from the hosel rim to the hosel base; the shaft having a top end that is received in the grip, a bottom end that is received in the hosel hole, and a diameter; the ferrule comprising a top edge, a bottom edge, a ledge, a centering region, and a tapered region, the ledge defining a boundary between the tapered region and the centering region, the centering region being the lower portion of the ferrule defined between the ledge and the bottom edge, the centering region being received in the hosel hole, and the tapered region being the upper portion of the ferrule defined between the ledge and the top edge; the tapered region comprising one or more weighting rings, each comprising a cylindrical tube having a top edge, a bottom edge, an inner surface, and an outer surface.

[0186] Clause 32: The golf club according to Clause 31, wherein one or more weighted rings are formed integrally with the tapered region.

[0187] Clause 33: The golf club as described in Clause 31, wherein the outer surface of each of the one or more weighted rings forms part of the outer surface of the ferrule.

[0188] Clause 34: A golf club as described in Clause 31, wherein the weighted rings may consist of one ring, two rings, three rings, four rings, or five rings.

[0189] Clause 35: A golf club as described in Clause 31, having one or more weighted rings that are 0.1 inches to 0.5 inches high.

[0190] Clause 36: A golf club as described in Clause 35, wherein each of the one or more weighted rings is the same height.

[0191] Clause 37: A golf club as described in Clause 35, wherein each of the weighted rings has a different height.

[0192] Clause 38: A golf club as described in Clause 31, wherein one or more weighted rings are 0.01 inches to 0.08 inches thick.

[0193] Clause 39: The golf club as described in Clause 31, wherein one or more weighted rings are formed from a metallic material selected from the group consisting of stainless steel, tungsten, tungsten-tenite propionate mixture, or stainless steel-tenite propionate mixture.

[0194] Clause 40: A golf club as described in Clause 31, wherein one or more weighted rings have a total mass of 1 gram to 10 grams.

[0195] Clause 41: A golf club comprising a club head, a shaft, and a grip, wherein the club head comprises a body and a hosel having a hole, and the shaft comprises a top end, a bottom end, a hot melt weight, and a cap, the top end being near the grip, the bottom end being near the club head on the opposite side of the top end, the bottom end being received within the hosel, the hot melt weight being formed inside the shaft near the bottom end, and the cap being fixed to the bottom end.

[0196] The replacement of one or more claimed elements constitutes a reconstruction, not a repair. Furthermore, benefits, other advantages, and solutions to problems have been described in relation to specific embodiments. However, benefits, advantages, solutions to problems, and any elements that can produce or make more prominent such benefits, advantages, or solutions should not be construed as essential, required, or necessary functions or elements of any or all claims unless such benefits, advantages, solutions, or elements are described in the claims.

[0197] Furthermore, embodiments and limitations disclosed herein are not provided to the public under the doctrine of Dedication if (1) embodiments and / or limitations are not expressly claimed in the claims and (2) are equivalent to, or could be equivalent to, the express elements and / or limitations of the claims under the doctrine of equivalents.

Claims

1. A golf club comprising a club head, shaft, and grip, The aforementioned club head comprises a body and a hosel, The hosel comprises a hosel hole having an inner surface that defines the hosel bonding region, The shaft comprises a shaft tip, a shaft rear end, and a shaft outer surface, The hosel hole receives the tip of the shaft that forms the head-shaft connection. The shaft defines a longitudinal axis extending from the geometric center of the rear end of the shaft to the geometric center of the tip of the shaft, The outer surface of the shaft defines a shaft joining region and an effective joining region near the tip of the shaft, wherein the shaft joining region is the portion of the outer surface of the shaft that is inserted into the hosel hole, and the effective joining region is the portion of the outer surface of the shaft that is in contact with the hosel joining region. The effective bonding region comprises a plurality of microgrooves, The plurality of microgrooves are recessed into the shaft from the outer surface of the shaft via a plurality of side walls, and the plurality of side walls increase the effective bonding area. The plurality of microgrooves are formed as lines and are defined as a first plurality of microgrooves extending in a first direction and a second plurality of microgrooves extending in a second direction. The first plurality of microgrooves and the second plurality of microgrooves are interconnected and extend circumferentially around the shaft, The grip is connected to the rear end of the shaft. Golf club.

2. The golf club according to claim 1, wherein the first plurality of microgrooves and the second plurality of microgrooves are formed integrally with the shaft.

3. The first plurality of microgrooves and the second plurality of microgrooves define the depth of each individual microgroove, The depth of each of the aforementioned microgrooves is less than 0.0038 inches. The golf club described in claim 1.

4. The first plurality of microgrooves and the second plurality of microgrooves define the total microgroove depth. The total microgroove depth is measured along the longitudinal axis, the total microgroove depth is the depth of the shaft tip having the microgrooves, and the total microgroove depth is between 1.00 inch and 3.00 inch. The golf club described in claim 1.

5. The golf club according to claim 1, wherein the first plurality of microgrooves and the second plurality of microgrooves cover 50% to 90% of the shaft joint area.

6. The golf club according to claim 1, wherein each of the plurality of microgrooves is provided with a base portion, the base portion is perpendicular to the plurality of side walls of the individual microgrooves, and the individual microgrooves are U-shaped in cross-section.

7. The golf club according to claim 1, wherein each microgroove of the first plurality of microgrooves extends in the first direction and is parallel to adjacent microgrooves of the first plurality of microgrooves, and each microgroove of the second plurality of microgrooves extends in the second direction and is parallel to adjacent microgrooves of the second plurality of microgrooves.

8. The golf club according to claim 7, wherein the first direction and the second direction are oblique to the longitudinal axis.

9. The golf club according to claim 8, wherein the first plurality of microgrooves and the second plurality of microgrooves provide resistance to normal forces and torsional forces.

10. The golf club according to claim 7, wherein the first direction is perpendicular to the longitudinal axis and the second direction is parallel to the longitudinal axis.

11. A golf club comprising a club head, shaft, and grip, The aforementioned club head comprises a body and a hosel, The hosel comprises a hosel hole having an inner surface that defines the hosel bonding region, The shaft comprises a shaft tip, a shaft rear end, and a shaft outer surface, The hosel hole receives the tip of the shaft that forms the head-shaft connection. The shaft defines a longitudinal axis extending from the geometric center of the rear end of the shaft to the geometric center of the tip of the shaft, The outer surface of the shaft defines a shaft joining region and an effective joining region near the tip of the shaft, wherein the shaft joining region is the portion of the outer surface of the shaft that is inserted into the hosel hole, and the effective joining region is the portion of the outer surface of the shaft that is in contact with the hosel joining region. The effective bonding region comprises a plurality of microgrooves, The plurality of microgrooves are recessed into the shaft from the outer surface of the shaft via a plurality of side walls, and the plurality of side walls increase the effective bonding area. The plurality of microgrooves are formed in a predetermined shape, The plurality of microgrooves are not interconnected and extend circumferentially around the shaft, The grip is connected to the rear end of the shaft. Golf club.

12. The golf club according to claim 11, wherein the plurality of microgrooves are formed integrally with the shaft.

13. The aforementioned plurality of microgrooves define the depth of each individual microgroove, The depth of each of the aforementioned microgrooves is less than 0.0038 inches. The golf club according to claim 11.

14. The aforementioned plurality of microgrooves define the total microgroove depth, The total microgroove depth is measured along the longitudinal axis, the total microgroove depth is the depth of the shaft tip having the microgrooves, and the total microgroove depth is between 1.00 inch and 3.00 inch. The golf club according to claim 11.

15. The golf club according to claim 11, wherein the plurality of microgrooves cover 50% to 90% of the shaft joint area.

16. The golf club according to claim 11, wherein each of the plurality of microgrooves is provided with a base portion, the base portion is perpendicular to the plurality of side walls of the individual microgrooves, and the individual microgrooves are U-shaped in cross-section.

17. The golf club according to claim 11, wherein each microgroove has a shape selected from the group consisting of triangles, lines, squares, rectangles, or spirals.

18. The golf club according to claim 17, wherein each of the microgrooves has the same shape.

19. The golf club according to claim 17, wherein each of the microgrooves has a different shape.

20. The golf club according to claim 11, wherein the plurality of microgrooves provide resistance to normal forces and torsional forces.

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