KR20250011578A - Golf club head - Google Patents

Abstract

A golf club head comprises a body having a loft between 20 degrees and 54 degrees, and an upper portion, a sole portion opposite the upper portion, a heel portion, a toe portion opposite the heel portion, and a hosel portion extending from the heel portion. The hosel portion comprises a hosel bore having an open end for receiving a golf club shaft and an abutting surface configured to support the golf club shaft, and a secondary recess extending sole-sideward from the abutting surface, the secondary recess comprising a volume between 2 cubic centimeters and 3.5 cubic centimeters. The golf club head further comprises a striking face defining a virtual face plane and having a center of the face, an imaginary vertical plane perpendicular to the virtual face plane and extending through the center of the face, and a center of gravity spaced less than or equal to 5 mm from the imaginary vertical plane.

Description

Golf Club Head {GOLF CLUB HEAD}

The present disclosure relates generally to the field of golf clubs. More specifically, it relates to a golf club head having an insert in at least a hosel portion of the club head.

The goal of golf club head design is to align the center of gravity of the club head with the location on the striking face where it is most likely to make contact with the golf ball during the swing. This increases shot accuracy and ensures that as much energy as possible from the golfer's swing is transferred to the golf ball at impact, resulting in a favorable golf shot.

However, this goal can often be difficult to achieve within the constraints of a given mass budget. In some instances, perimeter weighting can be added to an iron or wedge-type golf club head to increase its moments of inertia and thereby add "forgiveness" on off-center hits. However, these features can detrimentally affect the sweet spot location. Therefore, a need exists for a design that discretely moves weight from one portion of the club head to another to provide forgiveness on off-center hits while moving the center of gravity closer to where the golf ball is likely to be struck.

A golf club head according to one or more aspects of the present disclosure comprises a body having a loft of between 20 degrees and 54 degrees when oriented in a reference position, and including an upper portion, a sole portion opposite the upper portion, a heel portion, a toe portion opposite the heel portion, and a hosel portion extending from the heel portion. The hosel portion comprises a hosel bore having an open end for receiving a golf club shaft and an abutment surface configured to support the golf club shaft, and a secondary recess extending sole-sideward from the abutment surface, the secondary recess comprising a volume of between 2 cubic centimeters and 3.5 cubic centimeters. The golf club head further comprises a striking face defining a virtual face plane and having a center of mass, a virtual vertical plane perpendicular to the virtual face plane and extending through the center of mass, and a center of gravity spaced no more than 5 mm from the virtual vertical plane.

A set of golf club heads according to one or more aspects of the present disclosure comprises a first body having a first loft between 30 degrees and 54 degrees when oriented in a reference position, and a first upper portion, a first sole portion opposite the first upper portion, a first heel portion, a first toe portion opposite the first heel portion, and a first hosel portion extending from the first heel portion. The first hosel portion comprises a first hosel bore having a first open end for receiving a golf club shaft and a first abutting surface configured to support the golf club shaft, and an auxiliary recess extending sole-sideward from the abutting surface, the auxiliary recess comprising a volume greater than 2.25 cubic centimeters. A second golf club head includes a second body including a second loft of less than 30 degrees and a second upper portion, a second sole portion opposite the second upper portion, a second heel portion, a second toe portion opposite the second heel portion, and a second hosel portion extending from the second heel portion. The second hosel portion includes a second hosel bore having a second open end for receiving a golf club shaft and a second abutting surface configured to support the golf club shaft, and a second bore extending sole-sideward from the abutting surface, the second bore including a volume of less than 1 cubic centimeter.

A method of forming a correlated set of golf club heads comprises the steps of providing a first golf club head having a first striking face and a first hosel portion, the first hosel portion including a first hosel bore having a first open end configured to receive a golf club shaft and a first abutting surface configured to support the golf club shaft, and an auxiliary recess extending sole-side from the abutting surface, the auxiliary recess comprising a volume greater than 2.25 cubic centimeters, applying a coating to at least a first striking face of the first golf club head, and applying a first medium blast comprising aluminum oxide having a grit of between 180 and 120 to the first striking face. The method comprises the steps of providing a second golf club head having a second striking face and a second hosel portion, the second hosel portion including a second hosel bore having a second open end configured to receive a golf club shaft and a second abutting surface configured to support the golf club shaft, and a second bore extending sole-side from the abutting surface, the second bore comprising a volume less than one cubic centimeter, providing the second golf club head, applying a coating to at least the second striking face of the second golf club head, and applying a second medium blast to the second striking face, the second medium blast comprising a mix of aluminum oxide and a ceramic medium, wherein the aluminum oxide has a grit between 180 and 120.

These and other features and advantages of the golf club head and the method of making the same according to various embodiments of the present disclosure will become more apparent in consideration of the following description, drawings, and appended claims. The following description and drawings are for illustrative purposes only and are not intended to limit the scope of the present invention in any way.

FIG. 1 illustrates a front elevation view of an exemplary golf club head according to one or more aspects of the present disclosure.
FIG. 2 illustrates a rear schematic view of the exemplary golf club head of FIG. 1.
FIG. 3 illustrates a heel-side elevation view of an exemplary golf club head according to one or more aspects of the present disclosure.
FIG. 4 illustrates a cross-section of the golf club head of FIG. 3 along line IV-IV.
FIG. 5 illustrates a front perspective view of the golf club head of FIG. 3 with the hosel removed.
FIG. 6 illustrates a cross-section of the golf club head of FIG. 5 along line VI-VI.
FIG. 7 shows an exemplary method for manufacturing the golf club head of FIG. 3.
FIG. 8 is an enlarged view of an insert in the golf club head of FIG. 3.
FIG. 9 illustrates overlapping club heads as part of a method of designing the insert of FIG. 8.
FIG. 10 illustrates a golf club head produced from the second step of the method of FIG. 7.
FIG. 11 illustrates a golf club head produced from the third step of the method of FIG. 7.
FIG. 12 illustrates a golf club head produced from step 4 of the method of FIG. 7.
FIG. 13 illustrates an exemplary method for manufacturing a golf club head according to one or more aspects of the present disclosure.
FIG. 14 illustrates a golf club head produced from step 4 of the method of FIG. 13.
FIG. 15 illustrates a rear cut-away view of a golf club head according to one or more aspects of the present disclosure.
Figure 16 illustrates a heel-side cut-away view of the golf club head of Figure 15.
Figure 17 illustrates a rear schematic view of the golf club head of Figure 15.
FIG. 18 illustrates a cross-section of the golf club head of FIG. 17 along line XVIII-XVIII.
FIG. 19 illustrates a cross-section of the golf club head of FIG. 17 along line XIX-XIX.
FIG. 20 illustrates a rear perspective view of a golf club head according to a second embodiment of the present disclosure.
Figure 21 illustrates a bottom view of the golf club head of Figure 20.
Figure 22 illustrates a plan view of the golf club head of Figure 20.
Figure 23 illustrates a toe-side elevation view of the golf club head of Figure 20.
Figure 24 illustrates a heel-side elevation view of the golf club head of Figure 20.
FIG. 25 is a perspective view of a golf club head according to a third embodiment of the present disclosure.
Figure 26 illustrates a heel-side elevation view of the golf club head of Figure 25.
Figure 27 illustrates a toe-side elevation view of the golf club head of Figure 25.
Figure 28 illustrates a front elevation view of the golf club head of Figure 25.
Figure 29 illustrates a rear elevation view of the golf club head of Figure 25.
FIG. 30 illustrates a portfolio of golf club heads in a front elevation view according to another embodiment of the present disclosure.
Figure 31 illustrates the characteristics of golf club heads for bounce options #1 and #2.
FIGS. 32a through 32h illustrate characteristics and shapes of low-density inserts for golf club heads.
Figure 33 shows a plot comparing loft to CGy for various golf club heads.
Figure 34 shows a plot comparing loft to Iyy for various golf club heads.
Figure 35 shows a plot comparing loft to Iyy/CGy for various golf club heads.
Figure 36 illustrates a table listing various parameters of exemplary golf club heads.
Figures 37a and 37b show plots of Sdr values for various golf club heads.
Figure 38 illustrates R ² modeling of exemplary golf club heads.
Figures 39a and 39b illustrate plots of Spk/Sk and Svk/Sk, respectively, for various golf club heads.
FIG. 40 illustrates a front view of a golf club head according to the fourth embodiment of the present disclosure.
Figure 41 illustrates a rear view of the golf club head of Figure 40.
FIG. 42 illustrates a front view of another golf club head of the fourth embodiment of the present disclosure.
Figure 43 illustrates a rear view of the golf club head of Figure 42.
FIG. 44 is a partial rear view of an exemplary rear surface of a striking face of a common-back club head according to the present disclosure.

A golf club head (100) according to one or more aspects of the present disclosure is illustrated in FIGS. 1 and 2. The body of the golf club head may be bounded by a toe portion (110), a heel portion (120) opposite the toe portion, a top portion (130), and a sole portion (140) opposite the top portion. A hosel portion (150) for securing the club head to an associated shaft (not shown) may extend from the heel portion, the hosel portion eventually defining an imaginary central hosel axis (152).

The club head may further include a striking face (160) on its forward portion. The striking face is a substantially planar outer surface portion of the forward portion that substantially conforms to the virtual striking face plane (76) and is positioned to contact a golf ball at a factory-specified loft angle taken between the striking face plane (76) and the center hosel axis (152). The striking face may be formed with surface features that increase traction between the striking face and the struck golf ball to ensure good contact with the ball (e.g., in wet conditions) and impart a degree of spin to the ball, for example, to provide stability during flight through backspin or to better control the stopping position of the ball as it returns to the ground. A plurality of substantially parallel horizontal grooves or score lines (162) may be recessed from the striking face. A variety of low-scale features may be considered to form a textured pattern on the striking face.

The striking face may include a leading edge (161) forming a junction formed between a generally planar striking face (160) and a sole portion (140). The leading edge (161) includes a forward-most point (165) (see FIGS. 1 and 3 ). An imaginary vertical center plane (166) passes through the forward-most point (165) of the leading edge (161). The striking face may include a face center (164). As used herein, face center refers to a point on the striking face of a club head that is midway between the most sole-side range of score lines and passes through the imaginary center plane (166). In some embodiments, such as the embodiment illustrated in FIG. 1 , the face center is preferably also midway between the most heel-side range and the most toe-side range of score lines. However, in alternative embodiments, the face center is not located midway between the heel-most and toe-most extents of the scorelines. For example, the scorelines may be offset laterally from the leading edge contour, or the scorelines may extend completely into the toe portion of the striking face. A virtual vertical center plane (166) perpendicular to the face plane may be projected through the face center in a forward-backward direction of the club head, and a center of gravity (170) of the golf club head may be offset from the virtual vertical center plane. In FIG. 1, for example, the center of gravity may be offset heelward from the virtual vertical center plane. The center of gravity may be offset from the virtual vertical center plane by a distance (172) less than 5 mm, and in more preferred embodiments, less than 2.5 mm from the virtual vertical center plane.

A golf club head is illustrated in FIG. 1 as being in a "reference position." As used herein, the "reference position" refers to a position of a golf club head, e.g., the club head of FIG. 1, where a sole portion of the club head contacts an imaginary ground plane (10) such that an imaginary central hosel axis (152) of the hosel portion lies in an imaginary vertical hosel plane and score lines (162) are oriented horizontally with respect to the ground plane (10). Unless otherwise specified, all club head dimensions described herein are taken with the club head in the reference position.

The golf club head of FIGS. 1 and 2 preferably comprises an iron-type club head, such as a wedge-type club head, and preferably may have a loft angle of 39° or greater. More preferably, the golf club head may be a traditional blade-type club head, which may otherwise be referred to by certain golfers as a "player" type club head. As such, and as illustrated in FIG. 2, the rear portion (180) of the club head may include an upper blade portion (182) and a lower muscle portion (184). The upper blade portion may preferably comprise a substantially planar surface, and thus may preferably be free of any substantial perimeter-weighting features. The muscle portion may project rearwardly from the upper blade portion in a direction perpendicular to the plane of the striking face. The mass of the golf club head may generally be concentrated in the muscle portion, and thus the center of gravity (170) may be located sole-side of the center of the face. And, specifically, as illustrated in FIG. 2, the moment of inertia (“MOI”) Izz (186) of the golf club head may be measured about an imaginary vertical axis (187) passing through the center of gravity, and the MOI Iyy (188) of the golf club head may be measured about an imaginary horizontal axis (189) that is parallel to an imaginary ground plane and extends in the heel-toe direction and likewise passes through the center of gravity. As is known to those skilled in the art, MOI generally correlates with the natural resistance of a club head to rotation about a particular axis upon off-center golf ball impact.

Golf club heads of one or more embodiments of the present disclosure preferably have an internal structure that, compared to other "player" type golf club heads, discretely moves weight from the heel portion or lower hosel portion to the sole/muscle portion or upper portion of the hosel portion, thereby moving the center of gravity closer to the center of the face, i.e., to a location where a skilled golfer is more likely to strike a golf ball off the striking face, thereby increasing both the vertical MOI (Izz) and the horizontal MOI (Iyy). Exemplary golf club heads having such internal structures are described below. Each of these exemplary club heads may include the body structure described above with respect to FIGS. 1 and 2.

FIG. 4 illustrates a cross-section of a golf club head according to one embodiment of the present disclosure taken along line IV-IV of FIG. 3. As illustrated, a hosel portion (150) of the club head may include a hosel bore (154) extending a depth (155) into the hosel portion from an open upper end (156) of the hosel portion. The bore may have an upper inside diameter (157) and a lower inside diameter (158), which may be the same or different. And the hosel bore may terminate in a metal shelf (159) that projects inwardly toward an imaginary central hosel axis (152) at its bottom. The hosel portion sidewalls (as well as the remainder of the golf club head body) may preferably comprise a first component formed of a primary material, such as steel, and/or a material having a density of greater than or equal to 8 g/cm3 and/or a melting point of less than 1600° C. And the minimum thickness (151) of the hosel portion sidewall (preferably measured from the bottom of the hosel bore) may be sufficient to ensure structural integrity of the hosel portion without negatively affecting vibrational feedback for golf shots. For example, this minimum thickness may be at least 0.5 mm, more preferably at least 0.75 mm.

The bottom of the hosel bore may be an insert (190) (i.e., an "auxiliary insert") that serves as a second or auxiliary component. The auxiliary insert may include a substantially cylindrical portion (192) (FIG. 8) having a central axis coaxial with the imaginary central hosel axis (152). The insert may also include a heel portion shaped to generally conform to the heel contour of the golf club head. The insert may be formed of an auxiliary material, such as a ceramic, and preferably has a melting point greater than the melting point of the first component and a density less than the density of the first component. As such, the insert may have a mass of less than about 5 g in the golf club head, and may be less than 1.5% of the total mass of the golf club head. The insert may be comprised of at least 60 wt. % aluminum oxide (Al ₂ O ₃ ). More specifically, the ceramic insert may be composed of (by weight) 20% SiO ₂ , 10% ZrO ₂ , and 70% Al ₂ O ₃ , although each of these percentages may vary by up to about 10%. By adjusting the ceramic composition, the material properties of the insert may be tailored to achieve weight distribution targets, such as an increased moment of inertia, a lower and/or centered center of gravity location, or a particular vibration frequency during impact. The insert may also have the following properties: (i) a bond strength of 15 MPa; (ii) a porosity of no greater than 40%, preferably no greater than 30%; (iii) an absorption of 30%; (iv) a melting point greater than 2500° C.; and (v) a density of preferably no greater than 3 g/cm 3 , more preferably no greater than 2 g/cm 3 . However, as with the composition of the insert, the bond strength, porosity, absorption and density of the insert may be varied to achieve specific weight distribution goals.

As illustrated in FIG. 6, which illustrates a cross-section taken along line VI-VI of FIG. 5, the insert (190) may extend from the hosel portion into the heel portion of the golf club head. And this insert may affect various MOI values of the golf club head. For example, the vertical MOI Izz is preferably 2500 g·cm2 or greater, more preferably 3,000 g·cm2 or greater, and the horizontal MOI Iyy may be greater than 1,000 g·cm2.

FIGS. 7-12 illustrate an exemplary method (200) for forming the golf club heads of FIGS. 3-6. In a first step (210), the insert may be formed, for example, by injection molding. FIG. 8 illustrates one embodiment of an insert (190) after this first forming step. The insert may preferably be designed in a computer-aided design ("CAD") program by overlaying various club lofts and selecting an overlapping region of the club heads while taking into account any necessary constraints, such as minimum steel wall thickness for hosel and/or heel portion integrity. For example, FIG. 9 illustrates an insert formed in the overlapping region of club heads having lofts of 46°, 54°, and 64°. Such a design process may alleviate manufacturing concerns and may provide various cost advantages since a new insert does not have to be designed for each golf club head loft and sole shape. In one or more embodiments, the minimum wall thickness is at least 0.5 mm, more preferably at least 0.75 mm.

In a second step (220) illustrated in FIG. 7, the golf club head body may be formed, for example, by investment casting, around the insert (190) so as to at least partially and preferably substantially completely encapsulate the insert therein. The result of this step is illustrated in FIG. 10, where the insert is illustrated extending not only below the lower metal shelf (159) of the hosel bore, but also through the hosel bore and beyond the opening in the uppermost end (156) of the hosel portion (150). The upper portion (194) of the insert, i.e. the portions extending beyond the uppermost opening of the hosel portion and into the hosel bore, may then be removed, for example, by machining, in a third step (230) illustrated in FIG. 7. As shown in FIG. 11 which illustrates the result of this third step, the hosel bore (154) and the uppermost end (156) of the hosel portion may now be opened to accommodate a golf club shaft, and the insert (190) may extend to the sole side of the metal shelf (159) defining the lower portion of the hosel bore.

Also, as illustrated in FIG. 11, the insert extends toe-wise of the most heel-side extension of the scorelines. Preferably, the insert extends toe-wise of the most heel-side extent by at least 1 mm, more preferably by at least 2 mm, and even more preferably by at least 3 mm.

Thus, the discretionary mass is increased and relocated to parts of the club head that are better suited to achieve a desirable combination of mass properties, such as the location of the club head center of gravity (e.g. center of gravity height, center of gravity depth from the striking face, and lateral center of gravity clearance from the face center) and moments of inertia, in particular Iyy. This greater extension of the auxiliary insert into the central region may, in and of itself, result in a lateral shift of the center of gravity toward the toe, which goes against the natural tendency of a blade-like iron, e.g. wedge-shaped club head, to have a heel-oriented center of gravity. Furthermore, the greater extension of the auxiliary insert toward the toe means a larger insert volume and insert mass, as will be further explained below. Since the auxiliary insert preferably has a lower density than the body, the discretionary mass is increased, thereby enabling a greater increase in moments of inertia, e.g. Izz and Iyy, by selective relocation of this discretionary mass. It has been discovered that auxiliary inserts constructed in the manner described herein may be extended in the described manner without detrimentally affecting performance, including shot dispersion, feel at impact and acoustic considerations. Also preferably, in embodiments where such golf club heads are provided in a correlated set of club heads, the extension of the auxiliary insert toe-side of the most heel-side extent of the plurality of scorelines varies from club head to club head within the set as a function of loft. For example, the shaping and mass of lower lofted golf club heads may allow for a greater mass, and therefore volume, auxiliary insert.

And in the final step (240) of FIG. 7, the result is illustrated in FIG. 12, an insert cap (196) may be introduced into the hosel bore to rest on a metal lathe (159). This insert cap, which may be formed of aluminum or ABS plastic, may provide a protective barrier between the tip end of the shaft and the top end of the insert. In other embodiments, the insert cap may not be necessary because the top end of the insert is covered by the epoxy layer when the tip end of the shaft is attached to the hosel bore. Thus, by forming the body of the golf club head around the insert, space that would otherwise be filled by a denser metal material is instead occupied by, for example, a ceramic material. Thus, mass is selectively removed from the hosel and heel portions, thereby achieving the goal of moving the center of gravity closer to the center of the face.

Other exemplary club heads are believed to be within the spirit and scope of the present invention. For example, as illustrated in FIG. 13 and in the method of FIG. 7, the insert (390) may be first formed in the first step (310), such as by injection molding, followed by the body of the golf club head formed around the insert in the second step (320), such as by precision casting. However, in the third step (330), instead of removing only the upper portion of the insert to form the hosel bore of the hosel portion, more of the insert may be removed to form an internal cavity beneath the hosel bore. More specifically, and as illustrated in FIG. 14, a portion (392) of the insert, such as at least 50 volume percent, or all, may be removed to form the internal cavity, such as by mechanical agitation, chemical etching, or electrolytic etching. In some embodiments, the insert may be composed of a material having a high solubility in water or an aqueous solution. In such embodiments, the insert may be readily melted out of the golf club head to form a cavity. This cavity may then be filled by injecting therein a material, such as a polymer foam, which is later solidified in the fourth step (340) of FIG. 13. Thus, this fourth step may allow for the introduction of a vibration damping material into the club head, or for example, the adjustment of the center of gravity position by varying the density of the polymer material. Then, as in the method of FIG. 7, an insert cap may be introduced into the hosel bore in the fifth step (350) so as to rest on a metal shelf defining a lower portion of the hosel bore.

Other exemplary club heads are contemplated as being within the spirit and scope of the present invention. For example, as illustrated in the exemplary golf club head (400) of FIGS. 15-19, the insert (490) may extend much further into the sole portion of the golf club head, or even into the toe portion. The insert may extend substantially the entire distance from the heel to the toe. Such a configuration may be more feasible in "game improvement" type golf club heads, which generally have a larger sole volume to accommodate such an insert. A golfer using a "game improvement" club head may also perceive any change in sound and/or feel resulting from an insert extending into the striking face as less unpleasant. In fact, the presence of the insert may provide a vibration damping effect and may improve the feel of off-center impacts. And as illustrated in FIG. 19 which illustrates a cross-section taken along line XIX-XIX of the golf club head of FIG. 17, a high-density portion (492) may be co-molded with the insert in the toe portion or positioned within the insert. This high-density portion may be a metallic material, such as a tungsten alloy, and may have a density greater than 10 g/cm3. Including this high-density portion in the insert may be advantageous because it may add mass to the toe portion of the golf club head to increase the MOI, may improve the feel of the golf club head when striking a golf ball, and may ultimately reduce manufacturing costs.

Based on the above structural advancements, such as increasing discretionary mass while maintaining a relatively laterally centered center of gravity, greater consideration may be given to adapting the golf club head to a particular intended user. In considering the desired mass relocation, a model is generated that represents the impact probability for each of a plurality of locations around the club head's striking face. Next, certain performance characteristics, such as ball speed at impact and/or average carry distance, are measured at each of the plurality of locations around the striking face. By associating the probability model with such performance characteristics, a system can be generated that aggregates such information and, based thereon, calculates an overall performance value that represents what a golfer can expect to achieve over a large sampling of golf shots throughout a play.

As a result of the creation and implementation of these models, various attributes were considered relatively acceptable or with minimal gain in the case of additional manipulation. Other attributes were considered to be amenable to additional manipulation. That is, when changing certain attributes can have detrimental effects on other attributes, adopting a model that uses probabilistic overall performance can help to indicate the most desirable combination of attributes.

In particular, and by way of example, increasing Iyy has been shown to be worthy of greater consideration. In the particular case of wedge-shaped golf club heads, golfers tend to strike the golf ball on the striking face with a greater change in the vertical direction (compared to lower lofted iron-shaped golf clubs). However, the lateral location of the center of gravity remains an important characteristic of wedge-shaped golf club heads. In other golf club head aspects, for example, the height of the sweet spot on the striking face is also of particular importance.

For these reasons, the need has been identified to generally maintain, or at least limit their manipulation, of various desirable characteristics, such as sweet spot height and relatively centered lateral placement of the center of gravity, while manipulating other characteristics, such as those that would significantly increase Iyy.

This combination of more desirable properties can be achieved in a variety of ways. For example, and as previously described, the low-density insert (190) may comprise a greater mass, a greater volume, and thus a greater percent volume and percent mass of the overall golf club head.

First, the inventors have determined that larger insert masses are feasible without degrading the structural integrity of the golf club head below an acceptable threshold. Second, larger insert volumes can be achieved if multiple different low-density inserts are implemented across a set or portfolio or offering of multiple loft-variable golf club heads. If the auxiliary insert were limited to a single, identically structured component across all differently lofted (and otherwise different) club heads in a set or portfolio, the design envelope into which a low-density insert could fit was considered to be the net overlap space of all such golf club heads overlapping each other in the same orientation. Instead, if multiple different low-density inserts are allowed to be incorporated into a set of different lofted club heads, fewer overlapping club heads need to be overlapped per low-density insert, or none at all. As a result, the design envelope can generally be larger, allowing for greater overall design freedom across the set or offering.

According to the above, the low-density insert preferably has a density of 4 g/cc or less, more preferably 3 g/cc or less, even more preferably 2.5 g/cc or less, and even more preferably about 2 g/cc. Additionally or alternatively, the low-density insert has a mass Ma of 4 g or more, more preferably 5.5 g or more, more preferably 6 g or more, and even more preferably in the range of from 6 g to 8 g. While higher masses naturally result in greater discretionary mass, the upper limit in this case acknowledges practical manufacturing considerations, which may tend to exert downward pressure on the mass from a viewpoint of maintaining the structural integrity of the club head for a normal range of use cases. Additionally, there may be a diminishing return as the range of mass results from the extension of the auxiliary insert toward the toe of the most heel-side range of scorelines, since mass removed closer to the center location of the club head may have less of an effect on the MOI than mass removed from a location farther out at the club head end. Additionally or alternatively, the low-density insert comprises a volume greater than or equal to 2 cc, more preferably greater than or equal to 2.75 cc, more preferably within the range of 2.75 cc to 4 cc. This range reflects similar considerations described with respect to the auxiliary insert mass.

Additionally, or alternatively, in some embodiments, the auxiliary insert mass Ma constitutes a relatively large proportion of the overall mass Mh of the club head. The overall club head mass Mh is preferably at least 250 g and/or less than 320 g. More preferably, Mh is greater than or equal to 275 g and less than or equal to 310 g. Most preferably, Mh is in the range of 285 g to 305 g. Preferably, the ratio Ma/Mh is greater than or equal to 0.0185 and in some such embodiments greater than or equal to 0.020. Additionally, in some such embodiments, the ratio Ma/Mh is in the range of 0.0185 to 0.0275. These parameters may refer to the extent to which discretionary mass is created for redistribution in more beneficial areas of the club head, and may also refer to the extent to which mass is removed from less beneficial areas, thereby maintaining a center of gravity position that is laterally centered relative to the face center, such as as described herein.

However, as noted above, applying multiple low-density inserts to a set or offering of different lofted club heads allows for greater design freedom, at least for certain lofts. As used herein, an offering refers to a plurality of products having similar aesthetic and functional characteristics that are intended and presented as a single product line, such that a user is expected to select from the offering a set of all or fewer than all of the products of the offering to form a set or part of a set of golf clubs or golf club heads. As used herein, a set or related set refers to a plurality of products having similar or related functionality and/or aesthetics that are sold or offered for sale in combination. Thus, in addition to or alternatively to the above, the low-density insert volume is preferably related to the loft throughout the set or offering in the following manner:

Volume ≥ 0.0279 cc/°* Loft + 0.7805 cc

As an example, referring to FIG. 30, a portfolio of golf club heads is illustrated according to the disclosure, wherein various sets of golf club heads may be arranged. The portfolio includes a first subset of golf club heads (500A-500D), each of which preferably shares the same effective bounce (bounce option #1), but varies progressively in loft. The portfolio also includes a second subset of golf club heads, each of which preferably shares the same second bounce offering (bounce option #2), but varies progressively in loft. The first correlated set of iron-shaped, and more specifically wedge-shaped, club heads may comprise at least two, and more preferably at least three, different lofted club heads selected from the first subset. The correlated set of club heads may similarly be considered to comprise two or more different lofted club heads selected from the second subset. In some alternative embodiments, the correlation set may be comprised of different lofted club heads having different effective bounce properties. Properties of the club heads and inserts of bounce options #1 and #2 are illustrated in FIG. 31 . The golf club heads 500A through 500H may each include one of the low-density inserts 190A through 190F according to the present disclosure, wherein the low-density inserts have properties and shapes as illustrated in FIGS. 32A through 32H .

Accordingly, as illustrated in the charts and images of FIGS. 32A-32H , a set of golf club heads (e.g., a set or offering (568)) of at least four club heads having unique lofts, such as wedge-shaped golf club heads, is contemplated to include low-density inserts that differ (in the manner described with respect to FIG. 1 ) from one particular loft club head to another different loft club head and/or differ in other characteristics, such as a variation in bounce offering. More specifically, at least six unique auxiliary inserts (190A, 190B, 190C, 190D, 190E, and 190F) are implemented in a portfolio (568) of club heads that vary in some combination of lofts and effective bounces. In some embodiments, a unique auxiliary insert is provided for each unique club head in the portfolio. However, preferably, still some club heads among the portfolio have similar or identical auxiliary inserts. Thus, greater discretionary mass is achieved, and this discretionary mass may be redistributed to more desirable areas of the club head, or may be removed from areas of the club head where mass removal may be desirable, such as proximate the heel portion and/or very close to the y-axis (i.e., the horizontal heel-toe axis passing through the center of gravity of the club head when the club head is oriented in a reference position relative to the imaginary ground plane). As a result, Iyy may be further increased.

Preferably, in combination with enlarging the low-density insert as described above, the mass is relocated to various extremities of the club head, preferably closer to the hosel portion. For example, the hosel may be lengthened as a result of incorporating the low-density insert. Preferably, the hosel length is at least 78 mm, more preferably at least 80 mm, even more preferably about 85 mm, but preferably does not exceed 90 mm. In some such embodiments, the hosel length may be considered a function of loft, with lower-lofted club heads having a lower hosel length and higher-lofted club heads having a greater hosel length. For example, a club head according to the embodiment of FIG. 1 having a loft of about 42° to about 52° may have a hosel length of between about 75 mm and 82 mm, more preferably about 80 mm, while a club head according to the embodiment of FIG. 1 having a loft of about 56° to about 64° may have a hosel length of between about 83 mm and 88 mm, more preferably about 84 mm. In this way, the moment of inertia characteristics are further improved. For example, Iyy is likely to increase as mass is relocated further vertically about the y-axis. Izz may also increase as mass is relocated further laterally from the z-axis where Izz is measured. Furthermore, such properties increase the compensation due to the gain in Iyy with loft, exploiting the belief that impact variability increases with loft from a probabilistic perspective. Additionally, when mass is removed closer to the heel and relocated closer to the hosel, the preferred lateral (heel-toe) positioning of the center of gravity can generally be maintained (although changes in distance from the axis have a significantly greater effect on MOI than center of gravity location). Preferably, the center of gravity (670) is spaced from the imaginary vertical center plane (666) by a distance D7 (e.g., see FIG. 22) of no greater than 5 mm. However, given the greater mass and volume of the low-density insert, even greater improvements in this dimension can be achieved. Thus, D7 is more preferably no greater than 2.5 mm, and even more preferably no greater than 1.25 mm.

Additionally, the center of gravity (670) preferably has a depth (D5, see FIG. 23 , where a positive value corresponds to a rearward direction) from the striking face plane (676) measured perpendicular to the striking face plane of no more than 2.5 mm, more preferably no more than 2.25 mm, even more preferably no more than 2 mm. In some embodiments, the depth of the center of gravity may be a negative value, indicating that the center of gravity is forward of the striking face. Such embodiments are particularly feasible when a large amount of discretionary mass is incorporated into the hosel. These values on the one hand indicate that the golf club head is qualitatively blade-like or solid in appearance and/or feel. On the other hand, these values may serve as an indication that the club head sweet spot is relatively low on the striking face, which may be considered a particularly desirable feature with respect to a wedge-shaped golf club head, given the golf club head's ability to generate beneficial spin upon impact.

Additionally or alternatively, the depth of the center of gravity (D5) is preferably related to the club head loft. For example, preferably, D5 ≤ 7.69 mm - 0.074 mm/°* L. More preferably, D5 ≤ 7.19 mm - 0.074 mm/°* L. These relationships ensure the aforementioned advantages associated with D5 in absolute form, but take into account the natural tendency of D5 to vary in correlation with the club head loft.

Based on the above configuration, Iyy is preferably at least 1000 g*cm2, more preferably at least 1100 g*cm2. Additionally, or alternatively, Izz is preferably at least 3000 g*cm2, more preferably at least 3250 g*cm2, even more preferably at least 3300 g*cm2. These values are believed to increase the expected ball carry distance and/or the expected ball impact velocity as considered across an array of locations around the striking face using a probability-based model as described above, thereby increasing the overall expected performance of the golf club head.

Referring to FIG. 23, additionally or alternatively, the sweet spot (678) of the club head preferably has a height (D1) measured vertically from the virtual ground (10) of less than or equal to 24 mm, more preferably between 19 mm and 23 mm. Relatedly, the center of gravity preferably has a height (D3) of less than or equal to 22 mm, more preferably within a range of from 19 mm to 21.5 mm. Additionally or alternatively, the club head has an overall depth (D4) measured rearward from the striking face plane and in a direction perpendicular to the striking face plane, preferably within a range of from 23 mm to less than or equal to 22 mm, even more preferably between 17 mm and 22 mm. The club head further has a toe width dimension (D2), which is the lateral distance between the face center and the most toe-side extent of the club head. D2 is preferably 44 mm or greater, more preferably 45 mm or greater, and even more preferably within a range of 45 mm to 48 mm. Additionally or alternatively, the club head includes a club head height dimension (D6), which is a vertical extent of the body of the club head excluding the hosel portion. The height (D6) is preferably 38 mm or greater, and even more preferably within a range of 39 mm to 49 mm.

As mentioned above, from the perspective of probability-based modeling, it is considered that it may be more desirable to improve Iyy while maintaining or providing less improvement to Izz. Therefore, the ratio Iyy/Izz is preferably at least 0.25, more preferably at least 0.28, even more preferably at least 0.30, and even more preferably at least 0.32. Preferably, this ratio is in the range of 0.30 to 0.35. This characteristic further improves the overall probability-based expected performance of the club head.

In addition to the above, it has been found that club head loft plays a particularly important role in establishing an appropriate balance (and the relationships that govern them) between various mass-related parameters of a golf club head. For example, from a probability perspective, increasing loft is believed to result in greater user impact variability perpendicular to the club head striking face. This finding has led to a focus on how Iyy varies with loft, and in particular, greater attention has been paid to increasing Iyy as loft increases, sometimes at the expense of other attributes that are considered less important.

So, Iyy is preferably about loft for a club head (or two, three, or preferably all club heads in a set or portfolio of club heads) in the following way:

Iyy ≥ 16.63g·㎠/° × L + 114g·㎠.

While increasing Iyy is desirable along with increasing loft, this goal may come at the expense of increasing the lateral distance of the center of gravity from the face center (D7 in practical terms). Some increase in D7 may be considered acceptable, but preferably a threshold is still applied to limit this unintended increase. As a result, Iyy, D7 and loft are preferably related as follows:

Iyy/D7 ≥ 527.4g·cm/°× L - 23,580g·cm.

More preferably, Iyy, D7 and loft are related as follows:

Iyy/D7 ≥ 527.4g·cm/°× L - 22,170g·cm.

More preferably, Iyy, D7 and loft are related as follows:

Iyy/D7 ≥ 527.4g·cm/°× L - 20,760g·cm.

Additionally, or alternatively, D7 relates to loft for a club head (or two, preferably three, or more preferably all club heads of a set or portfolio of club heads) in the following manner:

D7 ≤ 10.1㎜ - 0.135㎜/°× L.

More preferably, D7 relates to loft for a club head (or two, preferably three, more preferably all club heads of a set or portfolio of club heads) in the following manner:

D7 ≤ 8.75㎜ - 0.135㎜/°× L.

Such relationships ensure that efforts to increase moment of inertia, particularly Iyy, and especially for higher lofted clubheads, do not result in unnecessary overall losses in performance due to unintended increases in D7.

Additionally, or alternatively, Iyy is preferably related to the loft in the following manner:

Iyy ≥ 16.63g·㎠/°×L + 114g·㎠.

The uniqueness of these relationships can be illustrated by the tables and plots of FIGS. 33-36 comparing exemplary embodiments of the present disclosure to known prior art golf clubs. For the purposes of this specification, "CGy" is definitionally equivalent to D7.

As previously mentioned, one feature that is particularly sought after in a wedge-shaped golf club head is the ability to generate backspin at impact. In addition to the aforementioned features such as sweet spot location and moment of inertia, other golf club head aspects can help contribute to the generation of backspin. One such attribute is the surface roughness characteristics of the striking face.

The surface roughness of the striking face of a golf club head, such as an iron-shaped, wedge-shaped golf club, is regulated in various ways by organizations that promulgate the rules governing the play of professional golf, such as the United States Golf Association (USGA). In particular, the USGA has promulgated rules governing equipment, including rules limiting aspects of surface roughness. These rules are considered, in part, to limit the average surface roughness (Ra) to 180 μin. However, the average surface roughness is only one way of describing the characteristics of a surface. Therefore, complex surface variations are still possible within the limits of this allowable space.

Therefore, it has been found that the overall performance, for example backspin generation, can be improved by appropriate selection of the surface finishing process, with particular attention to playing under wet conditions. Preferably, in addition to the scoreline formed in the above-described manner, the striking face is preferably textured by media blasting.

In one or more embodiments, the striking face is textured, preferably by a surface treatment process comprising a media blasting process. Certain processes and the structures produced therefrom have been shown to increase overall backspin generation, and more specifically to significantly increase backspin generation under wet conditions. Thus, by use of such processes and/or production of such finishes, the gap in spin performance typically understood to exist between dry and wet conditions is minimized, resulting in greater overall backspin generation as well as more consistent club head performance during use.

In some of these embodiments, the process for surface finishing the club head striking face comprises a first step of applying a coating, preferably a chrome plating. Preferably subsequent to the plating step (but optionally prior to the plating step), a second step of applying a medium blast to the striking face is performed. The step of applying the chrome plating surface is believed to be particularly effective under wet conditions, thereby helping to minimize the gap in spin performance between dry and wet conditions as described above.

Additionally, or alternatively, the surface texture varies from club head to club head within a correlated set of club heads, for example, within the correlated set of club heads described above.

More specifically, and by way of example, in some embodiments, the medium blasting step comprises applying aluminum oxide, preferably having a grit of 180 to 120. However, in other cases, and particularly in view of the particular loft, the step comprises applying a medium comprising a mix of ceramic medium and 180 to 120 grit aluminum oxide. Preferably, such mix has a volume ratio of aluminum oxide to ceramic of from about 8:1 to 10:1, more preferably about a volume ratio of aluminum oxide to ceramic of from about 9:1.

With respect to a portfolio or related set of golf club heads, e.g., the club head portfolios and sets described herein, preferably, one or more of the high loft club heads are subjected to a medium blast comprising 180 to 120 grit aluminum oxide, preferably not applied to the chrome plated striking face surface. Also preferably, one or more of the mid-lofted club heads (i.e., one or more club heads each having a less loft than the high loft club heads) of the same portfolio or set are subjected to a similar or identical medium blast, but with the addition of having such medium blast applied to the chrome plated surface. Also preferably, one or more of the lower lofted club heads (i.e., one or more club heads each having a loft less than that of the mid-lofted club heads) of the same portfolio or set are media blasted with a mix of aluminum oxide and ceramic, preferably having a volume ratio of aluminum oxide to ceramic of greater than that of the higher lofted club heads, more preferably from about 8:1 to 10:1 of aluminum oxide to ceramic, and even more preferably about 9:1 of aluminum oxide to ceramic. Also preferably, for the one or more of the lower lofted club heads, the media blast is preferably applied to the chrome plated surface. Incorporating ceramic into the media blast mix has been shown to be advantageous in that it does not impact the surface to the extent that pure aluminum oxide would, thereby resulting in a surface roughening effect that is consistent with the performance expectations specific to the loft. Also preferably, in any case where the media blast is applied to the chrome plated substrate striking face, the chrome layer is preferably not worn away throughout, exposing any underlying surface, thereby creating a risk of rust/oxidation of such underlying surface. In addition to the specific choice of medium blast, and the parameters governing the application of such medium blast, such as blast time and blast angle, it is preferred that the chromium layer be applied to a thickness sufficient so as not to be worn away in a manner that exposes any underlying surface. Additionally, or alternatively, a third step, preferably subsequent to the medium blasting step, is performed to further influence the final finished striking face texture. Preferably, laser etching is applied to the striking face. Additionally, in the case of sets or portfolios, the laser etching is applied in a manner that varies as a function of loft. For example, in some embodiments, the laser etching process results in horizontal "lines" interposed between the scorelines. The "lines" may correspond to texture regions defining regions of the face that are narrower in width and proportionally longer in length. Such laser etched regions may correspond to a single horizontal "line" extending solely in the heel-toe direction, or alternatively may correspond to a plurality of co-linear but distinct line segments, thus forming, for example, a dash-like appearance. Such laser etched regions may also be characterized by having structural features that are particularly deep compared to the surrounding striking face portion. More preferably, the laser etching process results in a combination of horizontal "lines" and angular line segments extending at an angle (e.g. 5°-80°, more preferably 15°-60°, as measured relative to the virtual ground position and in the striking face plane). Preferably, the number (and therefore the density) of the horizontal lines increases with loft. Furthermore, preferably, the angle of the angular laser etched region increases with increasing loft (and preferably also the overall density of the laser etched region per unit area of the striking face increases). In part, these laser etched areas provide additional roughening which is believed to have the effect of reducing the precision and Ra tolerance, allowing targeting of Ra values closer to the USGA limits. The addition of the laser etched areas has been shown to increase spin performance, especially in wet conditions. Additionally, these laser etchings provide the golfer with a visual cue as to the relative degree of surface roughness per lofted club head.

In some specific embodiments, a "raw" or unplated finish is desirable, as a subset of golfers prefer such an aesthetic and functional surface finish. In some such cases, the striking face is free of sacrificial or other coatings intended to minimize or prevent rust formation or oxidation. In some such cases, additional coatings or applications of chemicals are introduced to specifically accelerate or promote rust formation or oxidation. In such cases, the risk of corroding the rust inhibiting surface may be less relevant, and thus restrictions on, for example, the medium grit may be of less concern. Thus, for example, for a set or portfolio of club heads that are intended to have a raw finish, a greater variation in the medium grit may be applied. For example, in some such embodiments, one or more of the high loft club heads may be medium blasted with 60 grit aluminum oxide, the mid loft club heads may be medium blasted with 120 grit aluminum oxide, and the low loft club heads may be medium blasted with 180 grit aluminum oxide. In particular, the 60 grit aluminum oxide medium is preferably not applied, for example, to chrome plated club heads. However, alternative processes may be applied to allow such grit application, for example, by adjusting the method to thicken the chrome deposited layer.

In terms of structure, the process affects unique surface properties in a manner that is desirably variable across the set or portfolio depending on the loft. Preferably, for any individual club head, the surface texture properties are partly a function of the loft.

In general, as a critical matter, the finished striking face preferably satisfies the equipment rules promulgated by the USGA (and similar regulatory bodies). As noted above, these rules are generally understood to include a face texture (excluding the scoreline) on an iron-type club head having an average surface roughness (Ra) not exceeding 180 μin. The USGA equipment rules are also understood to limit the Rz of any striking texture (excluding the scoreline) on an iron-type club head to an Rz of no greater than 1000 μin. Accordingly, preferably, regardless of loft, the golf club head resulting from the surface finishing process described above has an Ra of no greater than 180 μin, and preferably an Rz of no greater than 1000 μin. In fact, for a portfolio or set of club heads, the Ra is preferably generally constant among two, more preferably three, and most preferably all different lofted club heads in the set or portfolio. For example, for two, three or all club heads in a set or portfolio with varying lofts, Ra is preferably maintained within a range of 120 μin to 180 μin, more preferably 140 μin to 180 μin.

Nevertheless, despite the relative consistency of Ra with varying loft, other standard surface roughness parameters are preferably the point of focus, and preferably vary as a function of loft. For example, the aforementioned variation in basal blast is believed to correlate with a high (and progressively increasing with loft) developed interfacial surface ratio Sdr. This parameter can be considered, from a practical standpoint, to be related to the relative surface area of the surface. Increasing surface area, which is considered relatively measurable in terms of Sdr, has been shown to have a significant increase in spin performance, particularly under wet spin conditions. In relation to FIG. 1 , the striking face surface of the golf club head described above preferably has an Sdr of at least 1%, more preferably at least 2%, and even more preferably at least 3%. These values, given the unique interaction between the metal face, the elastomeric golf ball coating and the moisture, result in a dynamic interaction that produces high performance with respect to backspin generation. Additionally, it is believed that these desirable performance results are achieved by certain synergistic results of these surface roughness properties in combination with the mass properties (e.g., center of gravity location, and moment of inertia characteristics) described above with respect to the embodiment of FIG. 1.

Additionally, or alternatively, the Sdr varies as a function of loft, and thus preferably within a correlated set or portfolio of golf club heads. For example, the absolute difference between the Sdr values of different lofted club heads of a common set is preferably at least 0.75%, more preferably at least 1.0%. Such variations and values are further illustrated in the plots shown in FIGS. 37a and 37b. Preferably, such variations occur between a first club head having a loft within the range of 46°-52° and a second club head having a loft within the range of 56° to 64°.

As may be the case with average surface roughness Ra and many common surface roughness parameters, a single attribute almost purely describes the resulting phenomenon without further validation. Sdr is believed to be highly correlated with performance, as shown in the plot of Fig. 38, which shows R ² modeling of example club heads according to the present disclosure.

However, it is additionally believed that a surface having a relatively uniformly distributed high surface area is the primary factor responsible for the significant gain in spin performance. The complex dynamic interactions described above are believed to be partly due to the cohesive properties of the water, the surface tension properties, and the absorption properties of the substrate material. In other words, a surface having a high Sdr by chance, but in a non-uniform manner, may not produce the beneficial results achieved herein. A useful means for quantifying this distinction from a practical standpoint is, for example, another common metrological parameter, the "reduced valley depth to core ratio" or Spk/Sk.

Additionally or alternatively to the above, the striking face of the club head of the above embodiments preferably has Spk/Sk of 2 or less, more preferably 1 or less, as shown in the plots of FIGS. 39a and 39b.

Additionally or alternatively, with respect to embodiments of the portfolio of club heads, preferably such portfolio includes wedge-shaped club heads having varying characteristics in addition to loft. For example, the portfolio of club heads preferably includes varying bounce offerings, e.g., a low bounce option, a mid bounce option, and a full bounce option. In such cases, along with the varying sole grind features, the leading edge radius varies in each of the low bounce, mid bounce, and full bounce instances. In particular, preferably, the leading edge radius increases from low bounce to mid bounce and from mid bounce to full bounce. Other club head embodiments are illustrated in FIGS. 20-24 . The golf club head (600) of FIGS. 20-24 preferably includes all of the features and characteristics described above with respect to the embodiment of FIG. 1 , but differs in external contour and appearance. For example, the club head (600) preferably includes a distinct mass feature (612), for example a triangular mass feature located in the upper toe region (610) of the club head aft of the striking face (660). Also preferably, a first reinforcing element (614) and a second reinforcing element (616) are located on the rear surface (682) of the striking face. These elements further facilitate ensuring the structural integrity of the club head while increasing any discretionary mass to achieve the potential properties described above in connection with the embodiment of FIG. 1.

In FIGS. 25 to 29 , other club head embodiments are illustrated. The golf club head (700) of FIGS. 25 to 29 preferably includes all the features and characteristics described above with respect to the embodiment of FIG. 1 , but differs in its external contour and appearance. For example, the club head (700) preferably includes a distinct mass feature (712), for example a triangular mass feature located in the upper toe region (710) of the club head rearward of the striking face (760). Also preferably, and particularly with respect to FIG. 29 , a medallion (714) is secured to the rear surface (782) of the striking face, and an insert (716), preferably in the form of a cover, is associated with a lower portion of the rear portion (780) of the club head, for example an upper surface of the muscle portion. The golf club head (700) generally takes the form of a wedge-shaped golf club head, such as a blade. However, the club may specifically include a "game improvement" style wedge-shaped club head having hybrid features that adapt the club head to higher handicap level golfers, for example. For example, the muscle portion may preferably include recesses having a mass feature having a density greater than that of the body and/or a rear-provided mass insert therein. For example, such an insert may have a density of at least 8 g/cc, more preferably at least 10 g/cc. For continuity, the recesses are covered by the cover described above, one of the recesses preferably being positioned proximate the heel portion (720) of the club head and the other preferably being positioned proximate the toe portion (710) of the club head. The cover may be mechanically secured to the muscle portion at the lower portion of the rear portion (780) of the club head, for example, by an interlocking fit, such as a press fit, and/or fasteners. Alternatively, or additionally, a chemical adhesive may be applied to bond the cover to such rear portion of the club head. Additionally, in some embodiments, and particularly with reference to FIG. 28, the striking face (760) of the club head may include a plurality of scorelines (762) extending substantially across the entire striking face. This allows for greater flexibility in shot selection for the golfer, as well as greater forgiveness for higher handicap golfers. This feature also benefits from the potential mass characteristics applied to the golf club head as described above in connection with the embodiment of FIG. 1. These elements facilitate ensuring structural integrity of the club head while increasing any discretionary mass required to achieve the potential characteristics described above in connection with the embodiment of FIG. 1.

FIGS. 40 through 44 illustrate other golf club head embodiments. Unless otherwise stated, the golf club heads illustrated and described in FIGS. 40 through 44 include substantially the same features and characteristics as those described above in connection with the embodiment of FIG. 1.

Moreover, the golf club heads illustrated and described, particularly in connection with FIGS. 40 and 42, may be components of a correlated set of club heads, and preferably may represent one or more other golf clubs (or club heads) within the correlated set of golf club heads. It should be appreciated that the set of golf club heads may include additional golf club heads including features similar to those illustrated and described in FIGS. 40 to 44.

The set of golf club heads may include a set of iron-type golf club heads. As such, the lofts of the golf club heads may vary within a range of between 18 degrees and 56 degrees, or between 20 degrees and 54 degrees. In some examples, the set of golf club heads may include "game improvement" style iron-type club heads. While the set of golf club heads disclosed herein may include hollow back style golf club heads, it should be appreciated that the set of golf club heads may additionally or alternatively include hollow golf club heads.

FIG. 40 illustrates a front view of a first golf club head (800) of a set of golf club heads. The golf club head (800) may include a higher lofted iron, and as such may include a loft between 30 degrees and 54 degrees. However, the features of the golf club head (800) illustrated and described in connection with FIG. 40 may be incorporated into iron-type golf club heads having a loft of less than 30 degrees or greater than 54 degrees. The golf club head (800) may include a body (802). The body (802) may include an upper portion (804), a sole portion (806) opposite the upper portion, a toe portion (808), and a heel portion (810) opposite the toe portion (808). The body (802) may further include a hosel portion (812) extending from the heel portion (810). The hosel portion (812) can include a hosel bore (814) having an open end (816) for receiving a golf club shaft and an abutting surface (818) configured to support the golf club shaft. The hosel portion (812) can include an auxiliary recess (820) extending sole-side from the abutting surface (818). In some examples, the auxiliary recess (820) can include a volume between about (e.g., +/- 0.1 cc) 1.5 cubic centimeters (cc) and about 4 cc, between about 2 cc and about 3.5 cc, or between about 2.2 cc and about 2.8 cc.

In some examples, the golf club head (800) can include an auxiliary component (822) positioned at least partially within the auxiliary recess (820). As described above, the auxiliary component (822) can be formed of a different material than the body (802) of the golf club head (800), and thus can include different material properties than the body (802). In some examples, the auxiliary component (822) can be at least partially encapsulated by the body (802). The auxiliary component (822) can be substantially similar to the insert (190) described above. The auxiliary component (822) can include a volume substantially similar to the auxiliary recess (820). Furthermore, the auxiliary component can include a mass of greater than or equal to 4.0 g, greater than or equal to 4.5 g, or greater than or equal to 5.0 g.

As illustrated in FIG. 40, incorporating a secondary component (822) within an iron-type club head may allow discretionary mass to be increased and relocated to portions of the club head that are better suited to achieve a desirable combination of mass properties, such as club head center of gravity location (e.g., center of gravity height, center of gravity depth from the striking face, and center of gravity lateral spacing from the face center) and moments of inertia, particularly Iyy or Izz, particularly when the secondary component (822) has a lower density than at least adjacent portions of the body or hosel area of the club head.

As illustrated in FIG. 40, the auxiliary recess (820) and the corresponding auxiliary component (822) can extend from the heel portion (810) toward the toe portion (808). In some examples, the auxiliary recess (820) and the auxiliary component (822) can extend only to the heel-most extent (823) of the scoreline (824) formed on the striking face (826) of the golf club head (800). Alternatively, in some examples, the auxiliary recess (820) and the auxiliary component (822) can terminate at a heel-side location of the heel-most extent (823) of the scorelines (824) (as illustrated in FIG. 40).

FIG. 41 illustrates a rear view of a golf club head (800) having an auxiliary recess (820) and an auxiliary component (822) disposed within the auxiliary recess (820). As described above, the golf club head (800) may include a perimeter weighting element (828) disposed on a rear surface of the striking wall, the perimeter weighting element (828) defining a rear open main cavity, thereby contributing to selective identification of the club head as a cavity-back style iron type golf club head.

FIG. 42 illustrates a front view of a second golf club head (900) of a set of golf club heads. The golf club head (900) may include, for example, a lower loft iron having a second loft less than the loft of the club head of FIG. 41 , and thus may include a loft of less than 30 degrees. However, the features of the golf club head (900) illustrated and described with respect to FIG. 42 may, in some examples, be incorporated into iron-type golf club heads having a loft greater than 30 degrees. The golf club head (900) may include a body (902). The body (902) may include an upper portion (904), a sole portion (906) opposite the upper portion (904), a toe portion (908), and a heel portion (910) opposite the toe portion (908). The body (902) can further include a hosel portion (912) extending from the heel portion (910). The hosel portion (912) can include a hosel bore (914) having an open end (916) for receiving a golf club shaft and an abutting surface (918) configured to support the golf club shaft. The hosel portion (912) can also include a second bore (920) extending sole-side from the abutting surface (918). In some examples, the second bore (920) and the hosel bore (914) extend along a hosel axis (922) of the hosel portion (912). In some examples, the second bore (920) can have a volume of less than about (e.g., +/- 0.1 cc) 1.0 cc, less than about 0.75 cc, or less than about 0.7 cc.

In some examples, the second bore (920) may be empty, or the second bore (920) may be partially or fully occupied by an insert or auxiliary component. In examples where the second bore (920) is occupied, the second bore (920) may be occupied by an auxiliary component similar to the auxiliary component illustrated and described with respect to FIGS. 40 and 41. However, the insert disposed within the second bore (920) will be sized to fit within the volume of the second bore (920).

FIG. 43 illustrates a rear view of a golf club head (900). As described above, the golf club head (900) may include a perimeter weighting element (924) disposed on the rear surface of the striking wall, which may contribute to identification of the club head (900) as a hollow-back style iron type golf club head.

In some examples, one or more of the lower lofted club heads (e.g., less than 30 degrees) in the set of clubs may omit the auxiliary recess and have a rigidly constructed hosel portion for example, for alternative features, while preferably one or more of the higher lofted club heads (e.g., having a loft greater than 30 degrees) include such an auxiliary recess. For example, the club head (900) may include a striking face (926) having a variable face thickness. In some such embodiments, this variable face thickness pattern is absent from the one or more high lofted club heads, or alternatively is different from a second variable face thickness pattern of the one or more high lofted club heads.

FIG. 44 illustrates a partial rearward view of an exemplary rear surface (928) of a striking face (926) of a club head (900). As illustrated in FIG. 44, the rear surface (928) includes recesses in an upper region, a center region, a toe region, and a lower region. More specifically, the rear surface (928) includes an upper region groove or channel (930), a toe region groove or channel (932), and a lower region groove or channel (934) adjacent a periphery of the rear surface (928). The center region recess (936) (or main recess) is formed in a center region between the upper region groove (930), the toe region groove (932), and the lower region groove (934).

The middle region (938) surrounds the center region recess (936) and each of the upper region groove (930), the toe region groove (932), and the lower region groove (934). Additionally, the middle region (938) has an average thickness greater than each of the center region recess (936), the upper region groove (930), the toe region groove (932), and the lower region groove (934).

Such variable face thicknesses may be used in lower lofted irons in lieu of the secondary recess and secondary components, since lower lofted irons may benefit less from the provision of the secondary recess. Instead, the variable face thickness may improve the mass and performance characteristics of the club head (900) while maintaining similar stress limits, appearance, and overall club head weight. In some examples, the improved mass and performance characteristics may include, for example, a coefficient of restitution (COR), characteristic time (CT), moment of inertia (MOI), and/or center of gravity (CG) location for the club head (900). In some examples, a hollow-back or hollow body, iron-type club head has an improved variable face thickness pattern that allows discretionary weight to be transferred from the striking face of the club head to other areas of the club head to improve the mass and/or performance characteristics of the club head (900). Advantageously, these club heads can have improved mass and performance characteristics, such as higher COR on the striking face, higher MOI, and more laterally centered, deeper, and lower CG locations than comparable club heads, while maintaining similar stress limits. Additionally, these club heads do not sacrifice the traditional appearance, dimensions (e.g., blade length, topline thickness) and overall club head weight (e.g., swing weight) that some players may prefer.

In some examples, in addition to or alternatively to the variable face thickness features described above, one or more of the lower lofted irons (e.g., less than 30 degrees) may include a different surface treatment applied to the striking face (926) of the golf club head (900) than the surface treatment applied to the striking face (826) of one or more of the higher lofted (e.g., between 30 and 54 degrees) clubs of the set of clubs.

For example, the first golf club head (800) may accommodate a coating applied to at least the striking face (826) of the first golf club head (800). The coating may comprise a chrome plating. Once the coating is applied to the striking face (826), a first medium blast may be applied to the striking face (826). The first medium blast may comprise a medium, such as aluminum oxide, and/or may have a grit between 180 and 120.

Alternatively or additionally, the second golf club head (900) may likewise receive a coating applied to at least the striking face (926) of the second golf club head (900) that is similar to, but preferably different from, the face coating discussed in connection with the club head (800). Such a coating may comprise a chrome plating. If the coating is applied to the striking face (926), a second medium blast may be applied to the striking face (926). In this case, the second medium blast preferably incorporates a different medium than the medium incorporated in connection with the face coating of the club head (800) described above. Such differences may lie, for example, in the composition of the medium and/or in the grit of the medium. For example, preferably, the second medium comprises a mixture of aluminum oxide and a ceramic medium, wherein the aluminum oxide has a grit of between 180 and 120. The second medium blast can include a volume ratio of aluminum oxide to ceramic medium of between 8:1 and 10:1, respectively. Different methods of surface finishing the higher and lower loft club sets can result in more desirable spin characteristics across a variety of shot types and under a variety of conditions, which can provide greater consistency across the set of golf clubs. These processes and results of such surface finishing have been previously described in more detail.

In the above discussion, the present invention has been described with reference to specific exemplary embodiments. However, it will be apparent that various modifications and changes may be made to these exemplary embodiments without departing from the broader spirit and scope of the present invention. Accordingly, the above discussion and the accompanying drawings should be considered as merely illustrative of the present invention rather than limiting the scope of the present invention in any way.

Claims (20)

As a golf club head, when oriented at a reference position with respect to a virtual ground plane,
Loft between 20 and 54 degrees,
As a body,
Upper part,
The sole part opposite the upper part,
Heel part,
The toe part opposite the heel part above,
As a hosel portion extending from the above heel portion,
A hosel bore having an open end for receiving a golf club shaft and an abutting surface configured to support said golf club shaft;
A hosel portion including an auxiliary recess extending sole-wise from said adjacent surface, said auxiliary recess including a volume of between 2 cubic centimeters and 3.5 cubic centimeters, and
The body, which includes a striking face defining a virtual face plane and having a face center,
a virtual vertical plane perpendicular to the above virtual face plane and extending through the center of the face, and
Center of gravity less than 5 mm from the above virtual vertical plane
A golf club head comprising: In paragraph 1,
A golf club head, wherein the body is formed of a first material having a first melting point and a first density, the golf club head further comprising an auxiliary component formed of a second material having a second melting point greater than the first melting point and a second density less than the first density, the auxiliary component being at least partially positioned within the auxiliary recess and at least partially encapsulated by the first material. In the second paragraph,
A golf club head, wherein the auxiliary component comprises a ceramic material. In the second paragraph,
A golf club head having a second density of 2.5 g/cm3 or less. In the second paragraph,
A golf club head, wherein the auxiliary component comprises a component mass Ma of 4.5 g or more. In the second paragraph,
A golf club head, wherein the auxiliary component comprises a component mass Ma of 5.0 g or more. In the second paragraph,
A golf club head, wherein the auxiliary component comprises a volume of 2.5 cc or more. In paragraph 1,
The above striking face is,
a central region including the center of the face and having a first average thickness;
an upper region above the central region and having a second average thickness;
The toe-side of the above central region, and the toe region having a third thickness,
an intermediate region at least partially surrounding said central region, and positioned between each of said upper region and said toe region and said central region, said intermediate region having a fourth average thickness greater than said first average thickness, said second average thickness, and said third average thickness;
A golf club head further comprising: In paragraph 1,
A golf club head further comprising a common back style head. As a set of golf club heads,
As the first golf club head,
First loft between 30 and 54 degrees, and
As the first body,
First upper part,
The first sole portion opposite the first upper portion,
Part 1 of the hill,
a first toe portion opposite the first heel portion, and
As a first hosel portion extending from the first heel portion,
A first hosel bore having a first open end for receiving a golf club shaft and a first abutting surface configured to support the golf club shaft, and
A first golf club head comprising a first body, said first hosel portion including a first auxiliary recess extending sole-side from said first adjacent surface and comprising a volume greater than 2.25 cubic centimeters;
As a second golf club head,
Second loft less than 30 degrees, and
As the second body,
Second upper part,
The second sole portion opposite the second upper portion,
Part 2 of the hill,
A second toe portion opposite the second heel portion, and
As a second hosel portion extending from the second heel portion,
a second hosel bore having a second open end for receiving a golf club shaft and a second abutting surface configured to support the golf club shaft; and
A second golf club head comprising a second body, said second hosel portion including a second auxiliary recess extending sole-wise from said second adjacent surface and comprising a volume of less than one cubic centimeter.
A set of golf club heads, including: In Article 10,
The above second body has a face center and
a central region including the center of the face and having a first average thickness;
an upper region above the central region and having a second average thickness;
The toe-side of the above central region, and the toe region having a third thickness,
an intermediate region at least partially surrounding said central region, and positioned between each of said upper region and said toe region and said central region, said intermediate region having a fourth average thickness greater than said first average thickness, said second average thickness, and said third average thickness;
A set of golf club heads further comprising a striking face including: In Article 10,
A set of golf club heads, wherein the second hosel bore and the second auxiliary recess extend along the hosel axis of the second hosel. In Article 10,
A set of golf club heads, wherein the first body is formed of a first material having a first melting point and a first density, the first golf club head further comprising an auxiliary component formed of a second material having a second melting point greater than the first melting point and a second density less than the first density, the auxiliary component being at least partially positioned within the first auxiliary recess and at least partially encapsulated by the first material. In Article 10,
A set of golf club heads, wherein the first golf club head and the second golf club head include common back style golf club heads. A method of forming a correlated set of golf club heads, comprising:
A step of providing a first golf club head having a first striking face and a first hosel portion, the first hosel portion including a first hosel bore having a first open end for receiving a golf club shaft and a first abutting surface configured to support the golf club shaft, and an auxiliary recess extending sole-side from the first abutting surface, the auxiliary recess including a volume greater than 2.25 cubic centimeters,
A step of applying a coating to at least the first striking face of the first golf club head;
A step of applying a first medium blast comprising aluminum oxide having a grit of between 180 and 120 to the first striking face;
A step of providing a second golf club head having a second striking face and a second hosel portion, the second hosel portion including a second hosel bore having a second open end for receiving a golf club shaft and a second abutting surface configured to support the golf club shaft, and a second bore extending sole-side from the second abutting surface, the second bore including a volume less than one cubic centimeter,
a step of applying said coating to at least said second striking face of said second golf club head, and
A step of applying a second medium blast comprising a mix of aluminum oxide and ceramic medium having a grit between 180 and 120 to the second striking face.
A method of forming a correlated set of golf club heads, comprising: In Article 15,
A method of forming a correlated set of golf club heads, wherein the coating comprises chrome plating. In Article 15,
A method of forming a correlated set of golf club heads, wherein each of the second medium blasts comprises a volume ratio of aluminum oxide to ceramic medium of from about 8:1 to about 10:1. In Article 15,
A method of forming a correlated set of golf club heads, wherein the correlated set of golf club heads comprises common back style golf club heads. In Article 15,
A method of forming a correlated set of golf club heads, wherein the first golf club head comprises a first body formed of a first material having a first melting point and a first density, the first golf club head further comprising an auxiliary component formed of a second material having a second melting point greater than the first melting point and a second density less than the first density, the auxiliary component being at least partially positioned within the auxiliary recess and at least partially encapsulated by the first material. In Article 15,
A method of forming a correlated set of golf club heads, further comprising the step of laser etching at least a portion of the first striking face of the first golf club head.