Golf club head

A golf club head designed to act under impact load as a bridge comprising a face; an inertial support system; a rear structure; and a force transfer system, under impact load the force transfer system, in cooperation with the inertial support system, elongating the rear structure and controlling the bending of the face, the pattern of bending of the face being a substantially bridge-like pattern of bending or a substantially modified bridge-like pattern of bending.

TECHNICAL FIELD AND BACKGROUND ART

The present invention relates to golf club heads and, more particularly, to the design of golf club heads.

In general, golf club heads are designed as either solid bodies (for example, persimmons), plates (for example, irons and putters with perimeter weights), or shells with a diaphragm face (for example, metal drivers and fairway woods). Today, the general consensus is that a shell with a diaphragm face provides the optimal design solution for a golf club head, with incremental improvements on that design helping to improve how far and how accurately a golfer can hit the golf ball.

For example, as discussed in U.S. Pat. No. 6,348,015, the face of a “shell” golf club head is designed from a material having a natural frequency between 2800 Hz and 4500 Hz. Upon hitting the material, the golf ball undergoes smaller deformations and, hence, lower energy losses. Or, as discussed in U.S. Pat. No. 6,348,013, a “shell” golf club head is designed with one or more recesses in one or more of the head's walls. The recesses increase the amount of time the face of the head remains in contact with the ball, again reducing energy loss.

Similarly, in U.S. Pat. No. 6,267,691, the face of a “shell” golf club is reinforced with parallel ribs along the back side of the face, controlling how the face bends under impact load. The ribs help resist bending of the face in a direction parallel to the ribs, but permit bending of the face in a direction perpendicular to the ribs. The reinforcing ribs help dampen the head's vibrations and give the face a larger region in which there is an efficient transfer of energy from the face to the ball (known as the “sweet spot”).

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a golf club head comprises a face, an inertial support system, a rear structure, and a force transfer system. Under impact load, the force transfer system elongates the rear structure and controls, in cooperation with the inertial support system, the bending of the face, the pattern of bending of the face being a substantially bridge-like, or substantially modified bridge-like, pattern of bending.

In a further embodiment of the invention, the rear structure cooperates with the force transfer system and the inertial support system in controlling the bending of the face, the pattern of bending of the face being a substantially bridge-like, or a substantially modified bridge-like, pattern of bending. In another further embodiment of the invention, during an off-center impact load, a part of the face moves forward relative to the inertial support system. In an additional embodiment of the invention, the force transfer system and the rear structure control the forward movement of the face.

In still another embodiment of the invention, the golf club head further comprises a torsion control system, which is operatively connected to the inertial support system. The torsion control system may comprise a cross-brace, an insert, some combination of a cross-brace and an insert, or some combination of a cross-brace and a portion of an insert. The insert may have a wall thickness that is constant, multiple, varying or profiled. In addition, the torsion control system may be re-configurable or replaceable.

In alternate embodiments of the invention, the inertial support system may include a hosel, and the mass of the inertial support system may be at least equal to the combined mass of the face, the force transfer system and the rear structure. Also, the inertial support system, the force transfer system, the face, the rear structure or the torsion control system may each be an integral unit, or some combination of the inertial support system, the force transfer system, the face, the rear structure or the torsion control system may be an integral unit. In addition, the force transfer system may be separated into one or more portions.

In further embodiments of the invention, the force transfer system may be the crown of the golf club head, the sole of the golf club head, or a combination of the crown and sole of the golf club head. Or, a part of the force transfer system may be the crown of the golf club head, the sole of the golf club head, or a combination of the crown and sole of the golf club head. In addition, the golf club head may include a conventional crown or a conventional sole. The conventional crown or conventional sole may be composed of a thermoset elastomer, a thermoplastic elastomer, or an engineering plastic. The thermoset elastomer, thermoplastic elastomer, or engineering plastic may be combined with fillers or fibers, such as glass or carbon, to form a composite structure. Also, the conventional crown or conventional sole may be transparent (in whole or in part) or translucent (in whole or in part).

In accordance with another aspect of the invention, a golf club head comprises a face and a substantially non-deforming mass connected to the face. Under impact load, the contact forces from the impact load, in connection with the resulting inertial reaction forces from the substantially non-deforming mass produce a pattern of bending of the face that is a substantially bridge-like, or substantially modified bridge-like, pattern of bending.

In accordance with still another aspect of the invention, a golf club head comprises a face, an inertial support system, a rear structure, and a force transfer system. Under on-center impact load, the force transfer system may be placed in a state of substantially pure axial compression.

In a further embodiment of the invention, the rear structure may be placed in a state of substantially pure axial tension under on-center impact load.

In accordance with a further aspect of the invention, a golf club head designed to act under impact load as a bridge comprises a face, the face acting as a bridge span; an inertial support system, the inertial support system acting as a bridge support; a rear structure and a force transfer system, the force transfer system and the rear structure acting together as a bridge truss.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

In accordance with one embodiment of the invention, a golf club head is designed to act as a “bridge” when the golf club head impacts a golf ball during game play (referred to hereinafter as “under impact load”). In general, the face of the golf club head corresponds to the bridge span, with the bridge truss and the bridge inertial supports located behind the face. As such, the bridge-like golf club head designs described herein are minimum weight structures that are inertially-supported under dynamic loading.

For ease of reference, the term “bridge” is used herein to refer to both a bridge structure and a modified bridge structure. In a bridge structure, most, if not all, of the characteristics of the structure are similar to the characteristics of a bridge—with few, if any, of the characteristics of other structures, such as a solid body, a plate, or a shell with a diaphragm face. In a modified bridge structure, some, but not all, of the characteristics of the structure are similar to the characteristics of a bridge—with additional characteristics of other structures, such as a solid body, a plate, or a shell with a diaphragm face.

In general, a golf club head designed to act, under impact load, as a bridge may have a sweet spot that extends across the height of the face of the golf club head and a center of mass that may be closer to the face of the golf club head. The bridge truss, located behind the face, may be tailored to provide a particular rate of deflection under impact load, and the bridge inertial supports may be tailored to provide a particular moment of inertia. Furthermore, the mass of the golf club head needed to support the impact load may be less than the mass needed in a “shell” golf club head. This leaves more mass available to optimize the inertial performance of the golf club head.

FIG. 1is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head100, face110is connected to inertial support system120and force transfer system130. In turn, rear structure140is connected to force transfer system130and face110. Force transfer system130comprises two component parts, inner structure130aand radial structure130b.

For ease of reference, the term “connection” is used herein to refer to physical connections between structures, as well as operational connections between structures. For example, the statement that structure A is connected to structure B may mean: (1) structure A is physically attached to structure B; (2) structure A interacts with structure B under operational conditions; or (3) structure A is physically attached to structure B and structure A interacts with structure B under operational conditions.

Inertial support system120, connected to the left side edge and right side edge of face110, provides support for the “bridge structure” of golf club head100. The bridge structure is that part of golf club head100required to support the impact load of a golf ball—face110, force transfer system130and rear structure140. Under impact load, the bridge structure transfers load to inertial support system120.

Under an off-center impact load, inertial support system120also opposes the “rotation” of golf club head100resulting from the off-center impact load. For example, when a golf club head hits a golf ball somewhere between the center of the face and the toe of the golf club head, the golf club head will rotate about a vertical axis. In turn, the golf ball will travel in an unintended direction. With opposition, such as that provided with inertial support system120, the rotation of the golf club head is reduced. In other words, inertial support system120produces high moments of inertia for golf club head100.

In general, under impact load, force transfer system130, in connection with inertial support system120, elongates rear structure140, controls the “bending” of face110(and thus the deflection of face110), and controls the rate of deflection of face110. For example, force transfer system130and inertial support system120may control the rate of deflection of face110at the same rate of deflection of a golf ball hit at a particular swing velocity, thereby achieving a good dynamic response and an impedance match between face110and the golf ball. In golfer parlance, a good impedance match means a good driving distance for the golf ball. In an alternate embodiment of golf club head100, rear structure140may also, in connection with force transfer system130and inertial support system120, control the bending of face110and control the rate of deflection of face110.

In addition, under an on-center impact load, with force transfer system130and rear structure140acting substantially in the manner of a bridge truss, force transfer system130and rear structure140are placed in a state of either substantial axial compression or substantial axial tension. In particular, inner structure130a and radial structure130b are placed in a state of substantial axial compression (a “push” along the length of a structure) and rear structure140is placed in a state of substantial axial tension (a “pull” along the length of a structure).

Under all impact loads, on-center and off-center, face110bends under the impact. As shown inFIG. 12a, however, the pattern of bending differs from the pattern of bending seen in the face of a “drum” golf club head. In a drum golf club head, also referred to herein as a diaphragm golf club head, the pattern of bending of the face as measured along a vertical line (in relation to the horizon) from the top edge of the face to the bottom edge of the face is not uniform. In other words, along a vertical line A0to A10, the rearward deflection of A0may not equal the rearward deflection of A1, the rearward deflection of A1may not equal the rearward deflection of A2, the rearward deflection of A2may not equal the rearward deflection of A3, etc. The reason for the non-uniform bending is inherent in the diaphragm golf club head's design, which requires rigid connections of the face along its top, bottom and side edges.

In golf club head100, the pattern of bending of face110is substantially uniform from the top edge of the face to the bottom edge of the face, as measured along a vertical line (in relation to the horizon) (hereinafter referred to as “bridge-like pattern of bending”). In other words, along a vertical line B0to B10, the rearward deflection of B0is substantially equal to the rearward deflection of B1, the rearward deflection of B1is substantially equal to the rearward deflection of B2, the rearward deflection of B2is substantially equal to the rearward deflection of B3, etc. Thus, in comparison to a diaphragm golf club head, which has a sweet “spot” (defined as a single point on the face of the diaphragm golf club head), face110has a sweet “line” (defined as a series of points on face110of golf club head100). The “sweet” region on the face of a golf club head is, in part, the region optimized to have efficient transfer of energy from the face of the golf club head to the golf ball.

A person of skill in the art understands that the phrase “along a vertical line (in relation to the horizon)” is used for ease of reference. In operation, in many golf club heads, the vertical axis of the club face may not be perpendicular to the horizon. Instead, the vertical axis of the club face may be angled in relation to the horizon (for example, oriented in relation to a particular “hit” distribution). Thus, in such a club face, the bridge-like pattern of bending may occur along a line substantially parallel to the vertical axis of the club face. In addition, in many golf club heads, the face of the golf club head may not be planar (for example, the face may have a roll). In such a club face, the bridge-like pattern of bending may occur along a line substantially tangential to the curved face of the golf club head. In other words, a bridge-like pattern of bending is a pattern of bending of face110that is substantially uniform from near the top edge of face110to near the bottom edge of face110, as measured along a vertical line (in relation to the horizon), as measured along a line substantially parallel to the vertical axis of face110(which may not be perpendicular to the horizon) or as measured along a line substantially tangential to a curve in face110.

In an alternate embodiment of golf club head100, the pattern of bending of face110is a “modified” bridge-like pattern of bending. In a modified bridge-like pattern of bending the maximum deflections (and rates of deflection) at various points of impact for various impacts, which occur over a substantial area of the face, have approximately the same value. In other words, in an area C of the face, the rearward deflection Z1from impact I1(which occurs at point [X1, Y1] on the face) is substantially equal to the rearward deflection Z2from impact I2(which occurs at point [X2, Y2] on the face), the rearward deflection Z2from impact I2is substantially equal to the rearward deflection Z3from impact I3(which occurs at point [X3, Y3] on the face), the rearward deflection Z3from impact I3is substantially equal to the rearward deflection Z4of impact I4(which occurs at point [X4, Y4] on the face), etc. Thus, despite the fact that impacts I1, I2, I3and I4are all at different points on face110, the deflections from the impacts are substantially equal, such that Z1≈Z2≈Z3≈Z4. . . ≈Zn. In addition, the rates of deflections from the impacts are also substantially equal, such that Ż1≈Ż2≈Ż3≈Ż4. . . ≈Zn.

In contrast, as shown inFIG. 12b, in a diaphragm golf club head, the maximum deflections (and rates of deflection) at vari ous points of impact for various impacts, which occur over a substantial area of the face, do not have approximately the same value. In other words, in an area D on the face, the rearward deflection Z1from impact I1(which occurs at point [X1, Y1] the face) is not substantially equal to the rearward deflection Z2from impact I2(which occurs at point [X2, Y2] on the face), the rearward deflection Z2from impact I2is not substantially equal to the rearward deflection Z3from impact I3(which occurs at point [X3, Y3] on the face), the rearward deflection Z3from impact I3is not substantially equal to the rearward deflection Z4of impact I4(which occurs at point [X4, Y4] on the face), etc. Thus, in a diaphragm golf club head, the deflections from the impacts are not substantially equal, such that Z1≈Z2≈Z3≈Z4. . . ≈Zn. In addition, the rates of deflection from the impacts are also not substantially equal, such that Ż1≈Ż2≈Ż3≈Ż4. . . ≈Żn.

In one embodiment of the invention, the “sweet” area of face110is more than approximately 25% of the area of face110. In all embodiments for the sweet regions (both lines and areas) of face110, the regions may be angled to better match the golf impact distribution for a particular golfer (or a group of golfers). For example, the sweet regions of face110may be angled at 30° from the horizontal.

As discussed, under an off-center impact load, face110bends with the bridge-like pattern of bending. In addition, during an off-center impact load, a part of face110moves forward relative to inertial support system120. Typically, the part of face110that moves forward relative to inertial support system120is opposite from the side of face110impacted by the golf ball. It is believed that the forward movement of face110under an off-center impact load, which the force transfer system and the rear structure control, accounts for one of the great characteristics of a bridge-like golf club head-the ability to drive the golf ball in its intended direction even though the golfer hit the golf ball off the center line of face110.

In an alternate embodiment of golf club head100, face110includes a “hinged” portion (or portions) that flex(es), acting as a hinge. The hinged portion, typically located to the right side edge or left side edge of face110, flexes under impact load. In other words, the hinged portion of face110rotates about the connection of face110and inertial support system120.

In a further alternate embodiment of golf club head100, the mass of inertial support system120is greater than, or equal to, the combined mass of face110, force transfer system130and rear structure140. Thus, in this alternate embodiment of golf club head100, at least 50% of the mass of golf club head100may be used to optimize moment of inertia values for golf club head100.

In still further alternate embodiments of golf club head100, face110may not be physically connected to inertial support system120(see corresponding golf club elements inFIG. 5) or face110may not be physically connected to rear structure140(not shown). However, under impact load, these alternate embodiments of golf club head100react the same as golf club head100. For example, inertial support system120provides support for the bridge structure of golf club head100, receiving the load during impact and, under off-center impact loads, opposing rotation of golf club head100. In addition, in connection with other systems, force transfer system130controls the bending of face110(and thus the deflection of face110) and controls the rate of deflection of face110.

FIG. 2is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head200, force transfer system230comprises three radial structures, notated as230b, rather than one radial structure. Under impact load, radial structures230breact in the same manner as radial structure130b. In other words, under an on-center impact load, radial structures230bare each placed in a state of substantially pure axial compression, exhibiting minimal bending. While the disclosed exemplary embodiments describe a force transfer system with either one radial structure or three radial structures, the force transfer system may comprise any number of radial structures. For example, the force transfer system may appear to the naked eye to be a “solid” structure but, on a microscopic level, is comprised of some number of radial structures. A person of skill in the art understands that, as the number of radial structures increases, the more closely the force transfer system approximates a minimum weight structure.

FIG. 3is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head300, face310is connected to inertial support system320, force transfer system330, and back350. In turn, rear structure340is connected to force transfer system330and face310. Force transfer system330comprises two component parts, inner structure330aand radial structure330b.

However, unlike the inertial support systems for golf club head100and200, the inertial support system for golf club head300is a set of concentrated mass elements (hereinafter referred to as “posts”). Under impact load, inertial support system320reacts in the same manner as inertial support systems120and220—providing support for the bridge structure of golf club head300, receiving the load during impact and, under off-center impact loads, opposing rotation of golf club head300.

In an alternate embodiment of golf club head300, inertial support system320is comprised of a set of posts connected with one or more bars. The bars may connect the posts along any point, or points, on the posts. For example, the bars may connect just the top of the posts, just the bottom of the posts, just the center of the posts, or both the top and the bottom of the posts.

FIG. 4is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head400, face410is connected to inertial support system420(which includes hosel450) and force transfer system430. In turn, rear structure440is connected to force transfer system430and face410. In this exemplary golf club head, the connection between face410and inertial support system420is line connection A, which is substantially perpendicular to the page. A line connection is a connection between two structures along a single set of points substantially forming a line. Force transfer system430comprises three component parts, inner structure430aand radial structures430b.

As shown inFIG. 4, inertial support system420is a set of posts, notated as420a, connected with a curved bar, notated as420b. Inertial support system420may straddle radial structures430b, may rest on top of radial structures430b, or may rest within radial structures430b. Under impact load, inertial support system420reacts in the same manner as inertial support systems120,220and320—providing support for the bridge structure of golf club head400, receiving the load during impact and, under off-center impact loads, opposing rotation of golf club head400.

FIG. 5is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. As noted above, inFIG. 5, face510is not physically connected to inertial support system520.

FIG. 6is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. Like golf club head500, face610is connected to force transfer system630and rear structure640, but is not physically connected to inertial support system620. Force transfer system630comprises eight component parts, inner structures630aand radial structures630b.

In addition, force transfer system630is separated into a top portion and a bottom portion. The separation may occur at any point along the height of force transfer system630, with the height of the top portion being equal to, less than, or greater than, the height of the bottom portion. Under impact load, golf club head600reacts the same as golf club heads100through500. In particular, force transfer system630produces the same effect produced in force transfer systems130through530—that is, in connection with inertial support system620(or, in an alternate embodiment, in connection with inertial support system620and rear structure640), elongating rear structure640, controlling the bending of face610(and thus the deflection of face610), and controlling the rate of deflection of face610.

In alternate embodiments of golf club head600, force transfer system630may be separated into a left portion and a right portion. The separation may occur at any point along the length of force transfer system630, with the length of the left portion being equal to, less than, or greater than, the length of the right portion. In addition, force transfer system630may be separated into more than two portions, with the height (or length) of each portion being equal to, less than, or greater than the height (or length) of any other portion. In addition, the separate portions of force transfer system630may not be “mirror images” of each other. In other words, the separate portions of force transfer system630may have different structures. For example, in a force transfer system with a top portion and a bottom portion, the top portion may be structured similar to force transfer system430(inFIG. 4) and the bottom portion may be structured similar to force transfer system230(inFIG. 2). Also, the separate portions of force transfer system630may be “misaligned” with one or more of the separate portions in a different plane than one or more of the other portions.

FIGS. 7aand7bare schematics of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head700, face710connects to inertial support system720and force transfer system730. In turn, rear structure740is connected to force transfer system730and face710.

Unlike force transfer systems130through630, force transfer system730comprises the crown of golf club head700. In particular, force transfer system730is a crown of varying thickness that acts as part of the bridge structure. For example, as shown inFIG. 7b, force transfer system730may have a single region, in which the thickness varies from the front of the region to the back of the region. Or, force transfer system730may have more than one region, in which the thickness of each region varies in the same manner or in different manners. For example, in each region the thickness may vary from the front of each region to the back of each region. Or, in a first region, the thickness may vary from the front of that region to the back of that region, in a second region, the thickness may vary from the center of that region to the edges of that region, etc. Under impact load, force transfer system730produces the same effect produced in force transfer systems130through630-that is, in connection with inertial support system720(or, in an alternate embodiment, in connection with inertial support system720and rear structure740), elongating rear structure740, controlling the bending of face710(and thus the deflection of face710), and controlling the rate of deflection of face710.

In an alternate embodiment of golf club head700, force transfer system730comprises the sole of golf club head700. In another alternate embodiment of golf club head700, force transfer system730comprises both the crown and the sole of golf club head700.

In another alternate embodiment of golf club head700, force transfer system730may comprise a part of the crown of golf club head700, the remaining part of force transfer system configured in a manner similar to the force transfer systems shown inFIGS. 1-6. Or, force transfer system730may comprise a part of the sole of golf club head700, the remaining part of force transfer system configured in a manner similar to the force transfer systems shown inFIGS. 1-6. Likewise, force transfer system730may comprise a part of the crown and a part of the sole of golf club head700, the remaining part of force transfer system configured in a manner similar to the force transfer systems shown inFIGS. 1-6.

FIG. 8is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head800(which is similar in structure to golf club head100), a torsion control system, identified as cross-brace850, is connected to rear structure840and force transfer system830. Under off-center impact load, cross-brace850provides torsional resistance to force transfer system830. In other words, in connection with inertial support system820, cross-brace850opposes the internal “rotation” (relative to inertial support system820) of force transfer system830resulting from an off-center impact load. In addition, in an off-center impact load, approximately one-half (left side or right side) of cross-brace850is placed in a state of substantially pure axial compression and approximately one-half (right side or left side) is placed in a state of substantially pure axial tension.

In an alternate embodiment of golf club head800, the mass of inertial support system820is no less than 30% of the combined mass of face810, force transfer system830, rear structure840and torsion control system850. Thus, in this alternate embodiment of golf club head800, a large portion of the mass of golf club head800may be used to optimize moment of inertia values for golf club head800.

FIG. 9is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head900(which is similar in structure to golf club head200), a torsion control system, identified as cross-brace950, is connected between the various approximate intersections of rear structure940, and/or inner structure930a, and/or radial structure930b, and/or face910. Like cross-brace850, cross-brace950provides torsional resistance to force transfer system930. In other words, in connection with inertial support system920, cross-brace950opposes the internal “rotation” (relative to inertial support system920) of force transfer system930resulting from an off-center impact load.

FIG. 10is a schematic of an exemplary embodiment of a golf club head designed to act, under impact load, as a bridge. In golf club head1000(which is similar in structure to golf club head500), a torsion control system, identified as insert1050, is placed in the “opening” between force transfer system1030and rear structure1040and/or in the “opening” between force transfer system1030, rear structure1040and face1010, and/or in the “opening” between force transfer system1030and face1010. As shown inFIG. 11a, insert1050is a “cored out” structure that comprises two component parts, web1052and flange1054. In contrast, insert1050may be a solid structure (not shown). In an alternate embodiment, as shown inFIG. 11b, insert1050may further comprise a cross-brace, such as cross-brace1056. Insert1050may also comprise a flange, such as flange1054, and a cross-brace, such as cross-brace1056. Insert1050may be composed of an assembly of multiple elements, the elements composed of metal, plastic or composite materials. Insert1050may also be composed, in whole or in part, of foam.

In addition, web1052may have constant wall thicknesses, multiple wall thicknesses, varying wall thicknesses or profiled wall thicknesses. For example, the inner edge of web1052(near inner structure1030a) may be thicker than the outer edge of web1052(near rear structure1040or inertial support system1020). In another alternate embodiment, the thickness of web1052may mirror the thickness of radial structure1030b. It may also be profiled to conform with the deformation of radial structure1030bunder center impact loading.

Like cross-braces850and950, insert1050provides torsional resistance to force transfer system1030. Thus, in connection with inertial support system1020, insert1050opposes the internal “rotation” (relative to inertial support system1020) of force transfer system1030resulting from an off-center impact load.

In tuning performance of the golf club head, the torsion control system (whether a cross-brace, an insert, or some combination of both) may be positioned at any point along the height of the force transfer system. In addition, the torsion control system may be positioned at different points along the height of the force transfer system for each “opening” in the golf club head. Further, one or more “openings” in the golf club head may contain more than one component of the torsion control system or, in the alternative, contain no component of the torsion control system. A person of skill in the art understands that tuning the torsion control system “tunes” the rate of deflection of the face and, in turn, the impedance match between the face of the golf club head and the ball.

The geometry and/or material property and/or attachment method of the torsion control system may also be varied to tune the performance of the golf club head. The performance tuning may occur at the time of manufacture, at the time of sale, or “in the field”—making the torsion control system re-configurable and/or replaceable. These “sets” of torsion control systems may be designed for the needs of a particular group of golfers or for the needs of a particular golfer.

In an alternate embodiment of each of the exemplary embodiments of golf club heads, the golf club heads may further include a back, such as back350in golf club head300. Or, in further alternative embodiments of each of the golf club heads, the back of the golf club head may be the rear structure or the inertial support system. In addition, the torsion control system may form all (or part) of the sole or crown of the golf club head. When forming all (or part) of the sole or crown of the golf club head, the torsion control system may be composed (in whole or part) of a material that provides scuff resistance for the golf club head, such as a plastic, metal (for example, thin titanium) or composite material (such as a combination of metal and plastic).

In other alternate embodiments of each of the exemplary embodiments of golf club heads, the face may be convex in shape from crown to sole (for example, a “roll”) or convex in shape from heel to toe (for example, a “bulge”) or convex in shape from crown to sole and heel to toe (for example, a combination of a “roll” and a “bulge”).

In a further alternate embodiment of each of the exemplary embodiments of golf club heads, the inertial support system further includes a hosel, such as hosel450in golf club head400. A hosel is a connection point on a golf club head to which a golf club shaft is attached. In addition, the golf club heads may include other “conventional” design options, such as offsets, face angles, loft angles or lie angles.

In still another embodiment of each of the exemplary embodiments of golf club heads, the face, the inertial support system, the force transfer system, the rear structure, and the torsion control system may be integral units alone or in combination with each other. For example, the face and the force transfer system may be an integral unit, the inertial support system may be an integral unit, the face, the force transfer system and the rear structure may be an integral unit, or the torsion control system, the inertial support system and the force transfer system may be an integral unit.

In a further embodiment of each of the exemplary embodiments of golf club heads, the golf club head may further include a conventional crown, a conventional sole, or a conventional crown and a conventional sole. The term “conventional” is used herein to differentiate from the “crown of varying thickness” described inFIG. 7. In order to ensure that a conventional crown or conventional sole do not negatively impact the bridge-like operation of the golf club heads described herein, the conventional crown or conventional sole may be composed of a thermoset elastomer, a thermoplastic elastomer, or an engineering resin. The thermoset elastomer, thermoplastic elastomer, or engineering plastic may be combined with fillers or fibers, such as glass or carbon, to form a composite structure. In addition, the conventional crown or conventional sole may be transparent (in whole or in part) or translucent (in whole or in part).