Patent Application
20200254315
The present application concerns golf club heads, and more particularly, golf club heads having unique relationships between the club head's mass moments of inertia and center-of-gravity position, golf club heads having a center of gravity projection that is near the center of the face of the golf club, golf club heads having unique relationships between loft and center of gravity projection location, and golf club heads having increased striking face flexibility.
Other patents and patent applications concerning golf clubs, such as U.S. Pat. Nos. 7,407,447, 7,419,441, 7,513,296, and 7,753,806; U.S. Pat. Appl. Pub. Nos. 2004/0235584, 2005/0239575, 2010/0197424, and 2011/0312347; U.S. patent application Ser. Nos. 11/642,310, and 11/648,013; and U.S. Provisional Pat. Appl. Ser. Nos. 60/877,336 are incorporated herein by reference in their entireties.
Center-of-gravity (CG) and mass moments of inertia critically affect a golf club head's performance, such as launch angle and flight trajectory on impact with a golf ball, among other characteristics.
A mass moment of inertia is a measure of a club head's resistance to twisting about the golf club head's center-of-gravity, for example on impact with a golf ball. In general, a moment of inertia of a mass about a given axis is proportional to the square of the distance of the mass away from the axis. In other words, increasing distance of a mass from a given axis results in an increased moment of inertia of the mass about that axis. Higher golf club head moments of inertia result in lower golf club head rotation on impact with a golf ball, particularly on “off-center” impacts with a golf ball, e.g., mis-hits. Lower rotation in response to a mis-hit results in a player's perception that the club head is forgiving. Generally, one measure of “forgiveness” can be defined as the ability of a golf club head to reduce the effects of mis-hits on flight trajectory and shot distance, e.g., hits resulting from striking the golf ball at a less than ideal impact location on the golf club head. Greater forgiveness of the golf club head generally equates to a higher probability of hitting a straight golf shot. Moreover, higher moments of inertia typically result in greater ball speed on impact with the golf club head, which can translate to increased golf shot distance.
Most fairway wood club heads are intended to hit the ball directly from the ground, e.g., the fairway, although many golfers also use fairway woods to hit a ball from a tee. Accordingly, fairway woods are subject to certain design constraints to maintain playability. For example, compared to typical drivers, which are usually designed to hit balls from a tee, fairway woods often have a relatively shallow head height, providing a relatively lower center of gravity and a smaller top view profile for reducing contact with the ground. Such fairway woods inspire confidence in golfers for hitting from the ground. Also, fairway woods typically have a higher loft than most drivers, although some drivers and fairway woods share similar lofts. For example, most fairway woods have a loft greater than or equal to about 13 degrees, and most drivers have a loft between about 7 degrees and about 15 degrees.
Faced with constraints such as those just described, golf club manufacturers often must choose to improve one performance characteristic at the expense of another. For example, some conventional golf club heads offer increased moments of inertia to promote forgiveness while at the same time incurring a higher than desired CG-position and increased club head height. Club heads with high CG and/or large height might perform well when striking a ball positioned on a tee, such is the case with a driver, but not when hitting from the turf. Thus, conventional golf club heads that offer increased moments of inertia for forgiveness often do not perform well as a fairway wood club head.
Although traditional fairway wood club heads generally have a low CG relative to most traditional drivers, such clubs usually also suffer from correspondingly low mass moments of inertia. In part due to their relatively low CG, traditional fairway wood club heads offer acceptable launch angle and flight trajectory when the club head strikes the ball at or near the ideal impact location on the ball striking face. But because of their low mass moments of inertia, traditional fairway wood club heads are less forgiving than club heads with high moments of inertia, which heretofore have been drivers. As already noted, conventional golf club heads that have increased mass moments of inertia, and thus are more forgiving, have been ill-suited for use as fairway woods because of their relatively high CG.
Accordingly, to date, golf club designers and manufacturers have not offered golf club heads with high moments of inertia for improved forgiveness and low center-of-gravity for playing a ball positioned on turf.
Additionally, due to the nature of fairway wood shots, most such shots are impacted below the center of the face. For traditionally designed fairway woods, this means that ballspeed and ball launch parameters are less than ideal. A continual challenge to improving performance in fairway woods and hybrid clubs is the limitation in generating ballspeed. In addition to the center of gravity and center of gravity projection, the geometry of the face and clubhead play a major role in determining initial ball velocity.
This application discloses, among other innovations, fairway wood-type golf club heads that provide improved forgiveness, ballspeed, and playability while maintaining durability.
The following describes golf club heads that include a body defining an interior cavity, a sole portion positioned at a bottom portion of the golf club head, a crown portion positioned at a top portion, and a skirt portion positioned around a periphery between the sole and crown. The body also has a forward portion and a rearward portion and a maximum above ground height.
Golf club heads according to a first aspect have a body height less than about 46 mm and a crown thickness less than about 0.65 mm throughout more than about 70% of the crown. The above ground center-of-gravity location, Zup, is less than about 19 mm and a moment of inertia about a center-of-gravity z-axis, Izz, is greater than about 300 kg-mm2.
Some club heads according to the first aspect provide an above ground center-of-gravity location, Zup, less than about 16 mm. Some have a loft angle greater than about 13 degrees. A moment of inertia about a golf club head center-of-gravity x-axis, Ixx, can be greater than about 170 kg-mm2. A golf club head volume can be less than about 240 cm3. A front to back depth (Dch) of the club head can be greater than about 85 mm.
Golf club heads according to a second aspect have a body height less than about 46 mm and the face has a loft angle greater than about 13 degrees. An above ground center-of-gravity location, Zup, is less than about 19 mm, and satisfies, together with a moment of inertia about a center-of-gravity z-axis, Izz, the relationship Izz≥13·Zup+105 .
According to the second aspect, the above ground center-of-gravity location, Zup, can be less than about 16 mm. The volume of the golf club head can be less than about 240 cm3. A front to back depth (Dch) of the club head can be greater than about 85 mm. The crown can have a thickness less than about 0.65 mm over at least about 70% of the crown.
According to a third aspect, the crown has a thickness less than about 0.65 mm for at least about 70% of the crown, the golf club head has a front to back depth (Dch) greater than about 85 mm, and an above ground center-of-gravity location, Zup, is less than about 19 mm. A moment of inertia about a center-of-gravity z-axis, Izz, specified in units of kg-mm2, a moment of inertia about a center-of-gravity x-axis, Ixx, specified in units of kg-mm2, and, the above ground center-of-gravity location, Zup, specified in units of millimeters, together satisfy the relationship Ixx+Izz≥20·Zup+165.
In some instances, the above ground center-of-gravity above ground location, Zup, and the moment of inertia about the center-of-gravity z-axis, Izz, specified in units of kg-mm2, together satisfy the relationship Izz≥13·Zup+105. In some embodiments, the moment of inertia about the center-of-gravity z-axis, Izz, exceeds one or more of 300 kg-mm2, 320 kg-mm2, 340 kg-mm2, and 360 kg-mm2. The moment of inertia about the center-of-gravity x-axis, Ixx, can exceed one or more of 150 kg-mm2, 170 kg-mm2, and 190 kg-mm2.
Some golf club heads according to the third aspect also include one or more weight ports formed in the body and at least one weight configured to be retained at least partially within one of the one or more weight ports. The face can have a loft angle in excess of about 13 degrees. The golf club head can have a volume less than about 240 cm3. The body can be substantially formed from a steel alloy, a titanium alloy, a graphitic composite, and/or a combination thereof. In some instances, the body is substantially formed as an investment casting. In some instances, the maximum height is less than one or more of about 46 mm, about 42 mm, and about 38 mm.
In golf club heads according to a fourth aspect, the crown has a thickness less than about 0.65 mm for at least about 70% of the crown, a front to back depth (Dch) is greater than about 85 mm, and an above ground center-of-gravity location, Zup, is less than about 19 mm. In addition, a moment of inertia about a center-of-gravity x-axis, Ixx, specified in units of kg-mm2, and the above ground center-of-gravity location, Zup, specified in units of millimeters, together satisfy the relationship Ixx≥7·Zup+60.
In some instances, the above ground center-of-gravity location, Zup, and the moment of inertia about the center-of-gravity z-axis, Izz, specified in units of kg-mm2, together satisfy the relationship Izz≥13·Zup+105.
The moment of inertia about the center-of-gravity z-axis, Izz, can exceed one or more of 300 kg-mm2, 320 kg-mm2, 340 kg-mm2, and 360 kg-mm2. The moment of inertia about the center-of-gravity x-axis, Ixx, can exceed one or more of 150 kg-mm2, 170 kg-mm2, and 190 kg-mm2.
Some embodiments according to the fourth aspect also include one or more weight ports formed in the body and at least one weight configured to be retained at least partially within one of the one or more weight ports.
According to the fourth aspect, the face can have a loft angle in excess of about 13 degrees. The golf club head can have a volume less than about 240 cm3. The body can be substantially formed from a selected material from a steel alloy, a titanium alloy, a graphitic composite, and/or a combination thereof. In some instances, the body is substantially formed as an investment casting. The maximum height of some club heads according to the fourth aspect is less than one or more of about 46 mm, about 42 mm, and about 38 mm.
In golf club heads according to a fifth aspect, the club head has a center of gravity projection (CG projection) on the striking surface of the club head that is located near to the center of the striking surface. In some instances, the center of gravity projection is at or below the center of the striking surface. For example, in some embodiments, the center of gravity projection on the striking surface is less than about 2.0 mm (i.e., the CG projection is below about 2.0 mm above the center of the striking surface), such as less than about 1.0 mm, or less than about 0 mm, or less than about −1.0 mm.
In some instances, the CG projection is related to the loft of the golf club head. For example, in some embodiments, the golf club head has a CG projection of about 3 mm or less for club heads where the loft angle is at least 16.2 degrees, and the CG projection is less than about 1.0 mm for club heads where the loft angle is 16.2 degrees or less.
In golf club heads according to a sixth aspect, the club head has a channel, a slot, or other member that increases or enhances the perimeter flexibility of the striking face of the golf club head in order to increase the coefficient of restitution and/or characteristic time of the golf club head. In some instances, the channel, slot, or other mechanism is located in the forward portion of the sole of the club head, adjacent to or near to the forwardmost edge of the sole.
The foregoing and other features and advantages of the golf club head will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
The following describes embodiments of golf club heads for metalwood type golf clubs, including drivers, fairway woods, rescue clubs, hybrid clubs, and the like. Several of the golf club heads incorporate features that provide the golf club heads and/or golf clubs with increased moments of inertia and low centers of gravity, centers of gravity located in preferable locations, improved club head and face geometries, increased sole and lower face flexibility, higher coefficients or restitution (“COR”) and characteristic times (“CT”), and/or decreased backspin rates relative to fairway wood and other golf club heads that have come before.
The following makes reference to the accompanying drawings which form a part hereof, wherein like numerals designate like parts throughout. The drawings illustrate specific embodiments, but other embodiments may be formed and structural changes may be made without departing from the intended scope of this disclosure. Directions and references (e.g., up, down, top, bottom, left, right, rearward, forward, heelward, toeward, etc.) may be used to facilitate discussion of the drawings but are not intended to be limiting. For example, certain terms may be used such as “up,” “down,”, “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships, particularly with respect to the illustrated embodiments. Such terms are not, however, intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same object.
Accordingly, the following detailed description shall not to be construed in a limiting sense and the scope of property rights sought shall be defined by the appended claims and their equivalents.
Normal Address Position
Club heads and many of their physical characteristics disclosed herein will be described using “normal address position” as the club head reference position, unless otherwise indicated.
As used herein, “normal address position” means the club head position wherein a vector normal to the club face 18 substantially lies in a first vertical plane (i.e., a vertical plane is perpendicular to the ground plane 17), the centerline axis 21 of the club shaft substantially lies in a second vertical plane, and the first vertical plane and the second vertical plane substantially perpendicularly intersect.
Club Head
A fairway wood-type golf club head, such as the golf club head 2, includes a hollow body 10 defining a crown portion 12, a sole portion 14 and a skirt portion 16. A striking face, or face portion, 18 attaches to the body 10. The body 10 can include a hosel 20, which defines a hosel bore 24 adapted to receive a golf club shaft. The body 10 further includes a heel portion 26, a toe portion 28, a front portion 30, and a rear portion 32.
The club head 2 also has a volume, typically measured in cubic-centimeters (cm3), equal to the volumetric displacement of the club head 2, assuming any apertures are sealed by a substantially planar surface. (See United States Golf Assocation “Procedure for Measuring the Club Head Size of Wood Clubs,” Revision 1.0, Nov. 21, 2003). In some implementations, the golf club head 2 has a volume between approximately 120 cm3 and approximately 240 cm3, such as between approximately 180 cm3 and approximately 210 cm3, and a total mass between approximately 185 g and approximately 245 g, such as between approximately 200 g and approximately 220 g. In a specific implementation, the golf club head 2 has a volume of approximately 181 cm3 and a total mass of approximately 216 g. Additional specific implementations having additional specific values for volume and mass are described elsewhere herein.
As used herein, “crown” means an upper portion of the club head above a peripheral outline 34 of the club head as viewed from a top-down direction and rearward of the topmost portion of a ball striking surface 22 of the striking face 18 (see e.g.,
As used herein, “sole” means a lower portion of the club head 2 extending upwards from a lowest point of the club head when the club head is at normal address position. In some implementations, the sole 14 extends approximately 50% to 60% of the distance from the lowest point of the club head to the crown 12, which in some instances, can be approximately 10 mm and 12 mm for a fairway wood. For example,
In other implementations, the sole 14 extends upwardly from the lowest point of the golf club body 10 a shorter distance than the sole 14 of golf club head 2. Further, the sole 14 can define a substantially flat portion extending substantially horizontally relative to the ground 17 when in normal address position. In some implementations, the bottommost portion of the sole 14 extends substantially parallel to the ground 17 between approximately 5% and approximately 70% of the depth (Dch) of the golf club body 10.
In some implementations, an adjustable mechanism is provided on the sole 14 to “decouple” the relationship between face angle and hosel/shaft loft, i.e., to allow for separate adjustment of square loft and face angle of a golf club. For example, some embodiments of the golf club head 2 include an adjustable sole portion that can be adjusted relative to the club head body 2 to raise and lower the rear end of the club head relative to the ground. Further detail concerning the adjustable sole portion is provided in U. S. Patent Application Publication No. 2011/0312347, which is incorporated herein by reference.
As used herein, “skirt” means a side portion of the club head 2 between the crown 12 and the sole 14 that extends across a periphery 34 of the club head, excluding the striking surface 22, from the toe portion 28, around the rear portion 32, to the heel portion 26.
As used herein, “striking surface” means a front or external surface of the striking face 18 configured to impact a golf ball (not shown). In several embodiments, the striking face or face portion 18 can be a striking plate attached to the body 10 using conventional attachment techniques, such as welding, as will be described in more detail below. In some embodiments, the striking surface 22 can have a bulge and roll curvature. For example, referring to
The body 10 can be made from a metal alloy (e.g., an alloy of titanium, an alloy of steel, an alloy of aluminum, and/or an alloy of magnesium), a composite material, such as a graphitic composite, a ceramic material, or any combination thereof. The crown 12, sole 14, and skirt 16 can be integrally formed using techniques such as molding, cold forming, casting, and/or forging and the striking face 18 can be attached to the crown, sole and skirt by known means.
For example, the striking face 18 can be attached to the body 10 as described in U.S. Patent Application Publication Nos. 2005/0239575 and 2004/0235584.
Referring to
In some embodiments, the striking face 18 is made of a composite material such as described in U.S. Patent Application Publication Nos. 2005/0239575, 2004/0235584, 2008/0146374, 2008/0149267, and 2009/0163291, which are incorporated herein by reference. In other embodiments, the striking face 18 is made from a metal alloy (e.g., an alloy of titanium, steel, aluminum, and/or magnesium), ceramic material, or a combination of composite, metal alloy, and/or ceramic materials. Examples of titanium alloys include 3-2.5, 6-4, SP700, 15-3-3-3, 10-2-3, or other alpha/near alpha, alpha-beta, and beta/near beta titanium alloys. Examples of steel alloys include 304, 410, 450, or 455 stainless steel.
When at normal address position, the club head 2 is disposed at a lie-angle 19 relative to the club shaft axis 21 and the club face has a loft angle 15 (
A club shaft is received within the hosel bore 24 and is aligned with the centerline axis 21. In some embodiments, a connection assembly is provided that allows the shaft to be easily disconnected from the club head 2. In still other embodiments, the connection assembly provides the ability for the user to selectively adjust the loft-angle 15 and/or lie-angle 19 of the golf club. For example, in some embodiments, a sleeve is mounted on a lower end portion of the shaft and is configured to be inserted into the hosel bore 24. The sleeve has an upper portion defining an upper opening that receives the lower end portion of the shaft, and a lower portion having a plurality of longitudinally extending, angularly spaced external splines located below the shaft and adapted to mate with complimentary splines in the hosel opening 24. The lower portion of the sleeve defines a longitudinally extending, internally threaded opening adapted to receive a screw for securing the shaft assembly to the club head 2 when the sleeve is inserted into the hosel opening 24. Further detail concerning the shaft connection assembly is provided in U.S. Patent Application Publication No. 2010/0197424, which is incorporated herein by reference.
Golf Club Head Coordinates
Referring to
The head origin coordinate system defined with respect to the head origin 60 includes three axes: a z-axis 65 extending through the head origin 60 in a generally vertical direction relative to the ground 17 when the club head 2 is at normal address position; an x-axis 70 extending through the head origin 60 in a toe-to-heel direction generally parallel to the striking surface 22, e.g., generally tangential to the striking surface 22 at the ideal impact location 23, and generally perpendicular to the z-axis 65; and a y-axis 75 extending through the head origin 60 in a front-to-back direction and generally perpendicular to the x-axis 70 and to the z-axis 65. The x-axis 70 and the y-axis 75 both extend in generally horizontal directions relative to the ground 17 when the club head 2 is at normal address position. The x-axis 70 extends in a positive direction from the origin 60 to the heel 26 of the club head 2. The y-axis 75 extends in a positive direction from the origin 60 towards the rear portion 32 of the club head 2. The z-axis 65 extends in a positive direction from the origin 60 towards the crown 12.
An alternative, above ground, club head coordinate system places the origin 60 at the intersection of the z-axis 65 and the ground plane 17, providing positive z-axis coordinates for every club head feature.
As used herein, “Zup” means the CG z-axis location determined according to the above ground coordinate system. Zup generally refers to the height of the CG 50 above the ground plane 17.
In several embodiments, the golf club head can have a CG with an x-axis coordinate between approximately −2.0 mm and approximately 6.0 mm, such as between approximately −2.0 mm and approximately 3.0 mm, a y-axis coordinate between approximately 15 mm and approximately 40 mm, such as between approximately 20 mm and approximately 30 mm, or between approximately 23 mm and approximately 28 mm, and a z-axis coordinate between approximately 0.0 mm and approximately −12.0 mm, such as between approximately −3.0 mm and approximately −9.0 mm, or between approximately −5.0 mm and approximately −8.0 mm. In certain embodiments, a z-axis coordinate between about 0.0 mm and about −12.0 mm provides a Zup value of between approximately 10 mm and approximately 19 mm, such as between approximately 11 mm and approximately 18 mm, or between approximately 12 mm and approximately 16 mm. Referring to
Another alternative coordinate system uses the club head center-of-gravity (CG) 50 as the origin when the club head 2 is at normal address position. Each center-of-gravity axis passes through the CG 50. For example, the CG x-axis 90 passes through the center-of-gravity 50 substantially parallel to the ground plane 17 and generally parallel to the origin x-axis 70 when the club head is at normal address position. Similarly, the CG y-axis 95 passes through the center-of-gravity 50 substantially parallel to the ground plane 17 and generally parallel to the origin y-axis 75, and the CG z-axis 85 passes through the center-of-gravity 50 substantially perpendicular to the ground plane 17 and generally parallel to the origin z-axis 65 when the club head is at normal address position.
Mass Moments of Inertia
Referring to
For example, a moment of inertia about the golf club head CG z-axis 85 can be calculated by the following equation
Izz=∫(x2+y2)dm (2)
where x is the distance from a golf club head CG yz-plane to an infinitesimal mass, dm, and y is the distance from the golf club head CG xz-plane to the infinitesimal mass, dm. The golf club head CG yz-plane is a plane defined by the golf club head CG y-axis 95 and the golf club head CG z-axis 85.
The moment of inertia about the CG z-axis (Izz) is an indication of the ability of a golf club head to resist twisting about the CG z-axis. Greater moments of inertia about the CG z-axis (Izz) provide the golf club head 2 with greater forgiveness on toe-ward or heel-ward off-center impacts with a golf ball. In other words, a golf ball hit by a golf club head on a location of the striking surface 18 between the toe 28 and the ideal impact location 23 tends to cause the golf club head to twist rearwardly and the golf ball to draw (e.g., to have a curving trajectory from right-to-left for a right-handed swing). Similarly, a golf ball hit by a golf club head on a location of the striking surface 18 between the heel 26 and the ideal impact location 23 causes the golf club head to twist forwardly and the golf ball to slice (e.g., to have a curving trajectory from left-to-right for a right-handed swing). Increasing the moment of inertia about the CG z-axis (Izz) reduces forward or rearward twisting of the golf club head, reducing the negative effects of heel or toe mis-hits.
A moment of inertia about the golf club head CG x-axis 90 can be calculated by the following equation
Ixx=∫(y2+z2)dm (1)
where y is the distance from a golf club head CG xz-plane to an infinitesimal mass, dm, and z is the distance from a golf club head CG xy-plane to the infinitesimal mass, dm. The golf club head CG xz-plane is a plane defined by the golf club head CG x-axis 90 and the golf club head CG z-axis 85. The CG xy-plane is a plane defined by the golf club head CG x-axis 90 and the golf club head CG y-axis 95.
As the moment of inertia about the CG z-axis (Izz) is an indication of the ability of a golf club head to resist twisting about the CG z-axis, the moment of inertia about the CG x-axis (Ixx) is an indication of the ability of the golf club head to resist twisting about the CG x-axis. Greater moments of inertia about the CG x-axis (Ixx) improve the forgiveness of the golf club head 2 on high and low off-center impacts with a golf ball. In other words, a golf ball hit by a golf club head on a location of the striking surface 18 above the ideal impact location 23 causes the golf club head to twist upwardly and the golf ball to have a higher trajectory than desired. Similarly, a golf ball hit by a golf club head on a location of the striking surface 18 below the ideal impact location 23 causes the golf club head to twist downwardly and the golf ball to have a lower trajectory than desired. Increasing the moment of inertia about the CG x-axis (Ixx) reduces upward and downward twisting of the golf club head 2, reducing the negative effects of high and low mis-hits.
Discretionary Mass
Desired club head mass moments of inertia, club head center-of-gravity locations, and other mass properties of a golf club head can be attained by distributing club head mass to particular locations. Discretionary mass generally refers to the mass of material that can be removed from various structures providing mass that can be distributed elsewhere for tuning one or more mass moments of inertia and/or locating the club head center-of-gravity.
Club head walls provide one source of discretionary mass. In other words, a reduction in wall thickness reduces the wall mass and provides mass that can be distributed elsewhere. For example, in some implementations, one or more walls of the club head can have a thickness (constant or average) less than approximately 0.7 mm, such as between about 0.55 mm and about 0.65 mm. In some embodiments, the crown 12 can have a thickness (constant or average) of approximately 0.60 mm or approximately 0.65 mm throughout more than about 70% of the crown, with the remaining portion of the crown 12 having a thickness (constant or average) of approximately 0.76 mm or approximately 0.80 mm. See for example
Thin walls, particularly a thin crown 12, provide significant discretionary mass compared to conventional club heads. For example, a club head 2 made from an alloy of steel can achieve about 4 grams of discretionary mass for each 0.1 mm reduction in average crown thickness. Similarly, a club head 2 made from an alloy of titanium can achieve about 2.5 grams of discretionary mass for each 0.1 mm reduction in average crown thickness. Discretionary mass achieved using a thin crown 12, e.g., less than about 0.65 mm, can be used to tune one or more mass moments of inertia and/or center-of-gravity location.
For example,
To achieve a thin wall on the club head body 10, such as a thin crown 12, a club head body 10 can be formed from an alloy of steel or an alloy of titanium. Thin wall investment casting, such as gravity casting in air for alloys of steel (
Referring to
Alternatively, a thin crown can be made from an alloy of titanium. In some embodiments of a titanium casting process, modifying the gating provides improved flow of molten titanium, aiding in casting thin crowns. For further details concerning titanium casting, please refer to U.S. Pat. No. 7,513,296, incorporated herein by reference. Molten titanium can be heated (1002) to between about 3000 degrees Fahrenheit and about 3750 degrees Fahrenheit, such as between about 3025 degrees Fahrenheit and about 3075 degrees Fahrenheit. In addition, the casting mold can be heated (1006) to between about 620 degrees Fahrenheit and about 930 degrees, such as about 720 degrees. The casting can be rotated in a centrifuge (1004) at a rotational speed between about 200 RPM and about 800 RPM, such as about 500 RPM. Molten titanium can be cast in the mold (1010) and the cast body can be cooled and/or heat treated (1012). The cast titanium body 10 can be extracted from the mold (1014) prior to applying secondary machining operations or attaching the striking face.
Weights and Weight Ports
Various approaches can be used for positioning discretionary mass within a golf club head. For example, many club heads have integral sole weight pads cast into the head at predetermined locations that can be used to lower, to move forward, to move rearward, or otherwise to adjust the location of the club head's center-of-gravity. Also, epoxy can be added to the interior of the club head through the club head's hosel opening to obtain a desired weight distribution. Alternatively, weights formed of high-density materials can be attached to the sole, skirt, and other parts of a club head. With such methods of distributing the discretionary mass, installation is critical because the club head endures significant loads during impact with a golf ball that can dislodge the weight. Accordingly, such weights are usually permanently attached to the club head and are limited to a fixed total mass, which of course, permanently fixes the club head's center-of-gravity and moments of inertia.
Alternatively, the golf club head 2 can define one or more weight ports 40 formed in the body 10 that are configured to receive one or more weights 80. For example, one or more weight ports can be disposed in the crown 12, skirt 16 and/or sole 14. The weight port 40 can have any of a number of various configurations to receive and retain any of a number of weights or weight assemblies, such as described in U.S. Pat. Nos. 7,407,447 and 7,419,441, which are incorporated herein by reference. For example,
Inclusion of one or more weights in the weight port(s) 40 provides a customizable club head mass distribution, and corresponding mass moments of inertia and center-of-gravity 50 locations. Adjusting the location of the weight port(s) 40 and the mass of the weights and/or weight assemblies provides various possible locations of center-of-gravity 50 and various possible mass moments of inertia using the same club head 2.
As discussed in more detail below, in some embodiments, a playable fairway wood club head can have a low, rearward center-of-gravity. Placing one or more weight ports 40 and weights 80 rearward in the sole as shown, for example, in
Club Head Height and Length
In addition to redistributing mass within a particular club head envelope as discussed immediately above, the club head center-of-gravity location 50 can also be tuned by modifying the club head external envelope. For example, the club head body 10 can be extended rearwardly, and the overall height can be reduced.
Referring now to
In some embodiments, the fairway wood golf club head 2 has a height (Hch) less than approximately 55 mm. In some embodiments, the club head 2 has a height (Hch) less than about 50 mm. For example, some implementations of the golf club head 2 have a height (Hch) less than about 45 mm. In other implementations, the golf club head 2 has a height (Hch) less than about 42 mm. Still other implementations of the golf club head 2 have a height (Hch) less than about 40 mm.
Some examples of the golf club head 2 have a depth (Dch) greater than approximately 75 mm. In some embodiments, the club head 2 has a depth (Dch) greater than about 85 mm. For example, some implementations of the golf club head 2 have a depth (Dch) greater than about 95 mm. In other implementations, as discussed in more detail below, the golf club head 2 can have a depth (Dch) greater than about 100 mm.
Forgiveness of Fairway Woods
Golf club head “forgiveness” generally describes the ability of a club head to deliver a desirable golf ball trajectory despite a mis-hit (e.g., a ball struck at a location on the striking surface 22 other than the ideal impact location 23). As described above, large mass moments of inertia contribute to the overall forgiveness of a golf club head. In addition, a low center-of-gravity improves forgiveness for golf club heads used to strike a ball from the turf by giving a higher launch angle and a lower spin trajectory (which improves the distance of a fairway wood golf shot). Providing a rearward center-of-gravity reduces the likelihood of a slice or fade for many golfers. Accordingly, forgiveness of fairway wood club heads, such as the club head 2, can be improved using the techniques described above to achieve high moments of inertia and low center-of-gravity compared to conventional fairway wood golf club heads.
For example, a club head 2 with a crown thickness less than about 0.65 mm throughout at least about 70% of the crown can provide significant discretionary mass. A 0.60 mm thick crown can provide as much as about 8 grams of discretionary mass compared to a 0.80 mm thick crown. The large discretionary mass can be distributed to improve the mass moments of inertia and desirably locate the club head center-of-gravity. Generally, discretionary mass should be located sole-ward rather than crown-ward to maintain a low center-of-gravity, forward rather than rearward to maintain a forwardly positioned center of gravity, and rearward rather than forward to maintain a rearwardly positioned center-of-gravity. In addition, discretionary mass should be located far from the center-of-gravity and near the perimeter of the club head to maintain high mass moments of inertia.
For example, in some of the embodiments described herein, a comparatively forgiving golf club head 2 for a fairway wood can combine an overall club head height (Hch) of less than about 46 mm and an above ground center-of-gravity location, Zup, less than about 19 mm. Some examples of the club head 2 provide an above ground center-of-gravity location, Zup, less than about 16 mm.
In addition, a thin crown 12 as described above provides sufficient discretionary mass to allow the club head 2 to have a volume less than about 240 cm3 and/or a front to back depth (Dch) greater than about 85 mm. Without a thin crown 12, a similarly sized golf club head would either be overweight or would have an undesirably located center-of-gravity because less discretionary mass would be available to tune the CG location.
In addition, in some embodiments of a comparatively forgiving golf club head 2, discretionary mass can be distributed to provide a mass moment of inertia about the CG z-axis 85, Izz, greater than about 300 kg-mm2. In some instances, the mass moment of inertia about the CG z-axis 85, Izz, can be greater than about 320 kg-mm2, such as greater than about 340 kg-mm2 or greater than about 360 kg-mm2. Distribution of the discretionary mass can also provide a mass moment of inertia about the CG x-axis 90, Icc, greater than about 150 kg-mm2. In some instances, the mass moment of inertia about the CG x-axis 85, Ixx, can be greater than about 170 kg-mm2, such as greater than about 190 kg-mm2.
Alternatively, some examples of a forgiving club head 2 combine an above ground center-of-gravity location, Zup, less than about 19 mm and a high moment of inertia about the CG z-axis 85, Izz. In such club heads, the moment of inertia about the CG z-axis 85, Izz, specified in units of kg-mm2, together with the above ground center-of-gravity location, Zup, specified in units of millimeters (mm), can satisfy the relationship
I
zz≥13·Zup+105.
Alternatively, some forgiving fairway wood club heads have a moment of inertia about the CG z-axis 85, Izz, and a moment of inertia about the CG x-axis 90, Ixx, specified in units of kg-mm2, together with an above ground center-of-gravity location, Zup, specified in units of millimeters, that satisfy the relationship
I
xx
+I
zz≥20·Zup+165 .
As another alternative, a forgiving fairway wood club head can have a moment of inertia about the CG x-axis, Ixx, specified in units of kg-mm2, and, an above ground center-of-gravity location, Zup, specified in units of millimeters, that together satisfy the relationship
I
xx≥7·Zup+60.
Coefficient of Restitution and Center of Gravity Projection
Another parameter that contributes to the forgiveness and successful playability and desirable performance of a golf club is the coefficient of restitution (COR) of the golf club head. Upon impact with a golf ball, the club head's face plate deflects and rebounds, thereby imparting energy to the struck golf ball. The club head's coefficient of restitution (COR) is the ratio of the velocity of separation to the velocity of approach. A thin face plate generally will deflect more than a thick face plate. Thus, a properly constructed club with a thin, flexible face plate can impart a higher initial velocity to a golf ball, which is generally desirable, than a club with a thick, rigid face plate. In order to maximize the moment of inertia (MOI) about the center of gravity (CG) and achieve a high COR, it typically is desirable to incorporate thin walls and a thin face plate into the design of the club head. Thin walls afford the designers additional leeway in distributing club head mass to achieve desired mass distribution, and a thinner face plate may provide for a relatively higher COR.
Thus, thin walls are important to a club's performance. However, overly thin walls can adversely affect the club head's durability. Problems also arise from stresses distributed across the club head upon impact with the golf ball, particularly at junctions of club head components, such as the junction of the face plate with other club head components (e.g., the sole, skirt, and crown). One prior solution has been to provide a reinforced periphery about the face plate, such as by welding, in order to withstand the repeated impacts. Another approach to combat stresses at impact is to use one or more ribs extending substantially from the crown to the sole vertically, and in some instances extending from the toe to the heel horizontally, across an inner surface of the face plate. These approaches tend to adversely affect club performance characteristics, e.g., diminishing the size of the sweet spot, and/or inhibiting design flexibility in both mass distribution and the face structure of the club head. Thus, these club heads fail to provide optimal MOI, CG, and/or COR parameters, and as a result, fail to provide much forgiveness for off-center hits for all but the most expert golfers.
In addition to the thickness of the face plate and the walls of the golf club head, the location of the center of gravity also has a significant effect on the COR of a golf club head. For example, a given golf club head having a given CG will have a projected center of gravity or “balance point” or “CG projection” that is determined by an imaginary line passing through the CG and oriented normal to the striking face 18. The location where the imaginary line intersects the striking face 18 is the CG projection, which is typically expressed as a distance above or below the center of the striking face 18. When the CG projection is well above the center of the face, impact efficiency, which is measured by COR, is not maximized. It has been discovered that a fairway wood with a relatively lower CG projection or a CG projection located at or near the ideal impact location on the striking surface of the club face, as described more fully below, improves the impact efficiency of the golf club head as well as initial ball speed. One important ball launch parameter, namely ball spin, is also improved.
The CG projection above centerface of a golf club head can be measured directly, or it can be calculated from several measurable properties of the club head. For example, using the measured value for the location of the center of gravity CG, one is able to measure the distance from the origin to the CG along the Y-axis (CGy) and the distance from the origin along the Z-axis (CGz). Using these values, and the loft angle 15 (see
CG_projection=[CGy−CGz*Tan(Loft)]*Sin(Loft)+CGz/Cos(Loft)
The foregoing equation provides positive values where the CG projection is located above the ideal impact location 23, and negative values where the CG projection is located below the ideal impact location 23.
Fairway wood shots typically involve impacts that occur below the center of the face, so ball speed and launch parameters are often less than ideal. This results because most fairway wood shots are from the ground and not from a tee, and most golfers have a tendency to hit their fairway wood ground shots low on the face of the club head. Maximum ball speed is typically achieved when the ball is struck at the location on the striking face where the COR is greatest.
For traditionally designed fairway woods, the location where the COR is greatest is the same as the location of the CG projection on the striking surface. This location, however, is generally higher on the striking surface than the below center location of typical ball impacts during play. For example,
In contrast to these conventional golf clubs, it has been discovered that greater shot distance is achieved by configuring the club head to have a CG projection that is located near to the center of the striking surface of the golf club head. Table 20B shows a plot of the golf club head CG projection versus the loft angle of the club head for several embodiments of the inventive golf clubs described herein. In some embodiments, the golf club head 2 has a CG projection that is less than about 2.0 mm from the center of the striking surface of the golf club head, i.e., −2.0 mm<CG projection<2.0 mm. For example, some implementations of the golf club head 2 have a CG projection that is less than about 1.0 mm from the center of the striking surface of the golf club head (i.e., −1.0 mm<CG projection<1.0 mm), such as about 0.7 mm or less from the center of the striking surface of the golf club head (i.e., −0.7 mm≤CG projection≤0.7 mm), or such as about 0.5 mm or less from the center of the striking surface of the golf club head (i.e., −0.5 mm≤CG projection≤0.5 mm).
In other embodiments, the golf club head 2 has a CG projection that is less than about 2.0 mm (i.e., the CG projection is below about 2.0 mm above the center of the striking surface), such as less than about 1.0 mm (i.e., the CG projection is below about 1.0 mm above the center of the striking surface), or less than about 0.0 mm (i.e., the CG projection is below the center of the striking surface), or less than about −1.0 mm (i.e., the CG projection is below about 1.0 mm below the center of the striking surface). In each of these embodiments, the CG projection is located above the bottom of the striking surface.
In still other embodiments, an optimal location of the CG projection is related to the loft 15 of the golf club head. For example, in some embodiments, the golf club head 2 has a CG projection of about 3 mm or less above the center of the striking surface for club heads where the loft angle is at least 15.8 degrees. Similarly, greater shot distance is achieved if the CG projection is about 1.4 mm or less above the center of the striking surface for club heads where the loft angle is less than 15.8 degrees. In still other embodiments, the golf club head 2 has a CG projection that is below about 3 mm above the center of the striking surface for club heads where the loft angle 15 is more than about 16.2 degrees, and has a CG projection that is below about 2.0 mm above the center of the striking surface for club heads where the loft angle 15 is 16.2 degrees or less. In still other embodiments, the golf club head 2 has a CG projection that is below about 3 mm above the center of the striking surface for golf club heads where the loft angle 15 is more than about 16.2 degrees, and has a CG projection that is below about 1.0 mm above the center of the striking surface for club heads where the loft angle 15 is 16.2 degrees or less. In still other embodiments, the golf club head 2 has a CG projection that is below about 3 mm above the center of the striking surface for golf club heads where the loft angle 15 is more than about 16.2 degrees, and has a CG projection that is below about 1.0 mm above the center of the striking surface for club heads where the loft angle 15 is between about 14.5 degrees and about 16.2 degrees. In all of the foregoing embodiments, the CG projection is located above the bottom of the striking surface. Further, greater initial ball speeds and lower backspin rates are achieved with the lower CG projections.
For otherwise similar golf club heads, it was found that locating the CG projection nearer to the center of the striking surface increases the COR of the golf club head as well as the ball speed values for balls struck by the golf club head. For example,
Increased Striking Face Flexibility
It is known that the coefficient of restitution (COR) of a golf club may be increased by increasing the height Hss of the striking face 18 and/or by decreasing the thickness of the striking face 18 of a golf club head 2. However, in the case of a fairway wood, hybrid, or rescue golf club, increasing the face height may be considered undesirable because doing so will potentially cause an undesirable change to the mass properties of the golf club (e.g., center of gravity location) and to the golf club's appearance.
As seen in
In the club head 200b embodiment shown in
In the club head 200d shown in
In the club head 210e shown in
Additional golf club head embodiments are shown in
Turning to
The club head 2 has a channel 212 located in a forward position of the sole 14, near or adjacent to the striking face 18. The channel 212 extends into the interior of the club head body 10 and has an inverted “V” shape defined by a heel channel wall 214, a toe channel wall 216, a rear channel wall 218, a front channel wall 220, and an upper channel wall 222. In the embodiment shown, the upper channel wall 222 is semi-circular in shape, defining an inner radius Rgi and outer radius Rgo, extending between and joining the rear channel wall 218 and front channel wall 220. In other embodiments, the upper channel wall 222 may be square or another shape. In still other embodiments, the rear channel wall 218 and front channel wall 220 simply intersect in the absence of an upper channel wall 222.
The channel 212 has a length Lg along its heel-to-toe orientation, a width Wg defined by the distance between the rear channel wall 218 and the front channel wall 220, and a depth Dg defined by the distance from the outer surface of the sole portion 14 at the mouth of the channel 212 to the uppermost extent of the upper channel wall 222. In the embodiment shown, the channel has a length Lg of from about 50 mm to about 90 mm, or about 60 mm to about 80 mm. Alternatively, the length Lg of the channel can be defined relative to the width of the striking surface Wss. For example, in some embodiments, the length of the channel Lg is from about 80% to about 120%, or about 90% to about 110%, or about 100% of the width of the striking surface Wss. In the embodiment shown, the channel width Wg at the mouth of the channel can be from about 3.5 mm to about 8.0 mm, such as from about 4.5 mm to about 6.5 mm, and the channel depth Dg can be from about 10 mm to about 13 mm.
The rear channel wall 218 and front channel wall 220 define a channel angle β therebetween. In some embodiments, the channel angle β can be between about 10° to about 30°, such as about 13° to about 28°, or about 13° to about 22°. In some embodiments, the rear channel wall 218 extends substantially perpendicular to the ground plane when the club head 2 is in the normal address position, i.e., substantially parallel to the z-axis 65. In still other embodiments, the front channel wall 220 defines a surface that is substantially parallel to the striking face 18, i.e., the front channel wall 220 is inclined relative to a vector normal to the ground plane (when the club head 2 is in the normal address position) by an angle that is within about ±5° of the loft angle 15, such as within about ±3° of the loft angle 15, or within about ±1° of the loft angle 15.
In the embodiment shown, the heel channel wall 214, toe channel wall 216, rear channel wall 218, and front channel wall 220 each have a thickness 221 of from about 0.7 mm to about 1.5 mm, e.g., from about 0.8 mm to about 1.3 mm, or from about 0.9 mm to about 1.1 mm. Also, in the embodiment shown, the upper channel wall outer radius Rgo is from about 1.5 mm to about 2.5 mm, e.g., from about 1.8 mm to about 2.2 mm, and the upper channel wall inner radius Rgi is from about 0.8 mm to about 1.2 mm, e.g., from about 0.9 mm to about 1.1 mm.
A weight port 40 is located on the sole portion 14 of the golf club head 2, and is located adjacent to and rearward of the channel 212. As described previously in relation to
In the embodiment shown, the weight port 40 is located adjacent to and rearward of the rear channel wall 218. One or more mass pads 210 may also be located in a forward position on the sole 14 of the golf club head 2, continguous with both the rear channel wall 218 and the weight port 40, as shown. As discussed above, the configuration of the channel 212 and its position near the face plate 18 allows the face plate to undergo more deformation while striking a ball than a comparable club head without the channel 212, thereby increasing both COR and the speed of golf balls struck by the golf club head. By positioning the mass pad 210 rearward of the channel 212, the deformation is localized in the area of the channel 212, since the club head is much stiffer in the area of the mass pad 210. As a result, the ball speed after impact is greater for the club head having the channel 212 and mass pad 210 than for a conventional club head, which results in a higher COR.
Turning next to
The club head 2 has a channel 212 located in a forward position of the sole 14, near or adjacent to the striking face 18. The channel 212 extends into the interior of the club head body 10 and has an inverted “V” shape defined by a heel channel wall 214, a toe channel wall 216, a rear channel wall 218, a front channel wall 220, and an upper channel wall 222. In the embodiment shown, the upper channel wall 222 is semi-circular in shape, defining an inner radius Rgi and outer radius Rgo, extending between and joining the rear channel wall 218 and front channel wall 220. In other embodiments, the upper channel wall 222 may be square or another shape. In still other embodiments, the rear channel wall 218 and front channel wall 220 simply intersect in the absence of an upper channel wall 222.
The channel 212 has a length Lg along its heel-to-toe orientation, a width Wg defined by the distance between the rear channel wall 218 and the front channel wall 220, and a depth Dg defined by the distance from the outer surface of the sole portion 14 at the mouth of the channel 212 to the uppermost extent of the upper channel wall 222. In the embodiment shown, the channel has a length Lg of from about 50 mm to about 90 mm, or about 60 mm to about 80 mm. Alternatively, the length Lg of the channel can be defined relative to the width of the striking surface Wss. For example, in some embodiments, the length of the channel Lg is from about 80% to about 120%, or about 90% to about 110%, or about 100% of the width of the striking surface Wss. In the embodiment shown, the channel width Wg at the mouth of the channel can be from about 3.5 mm to about 8.0 mm, such as from about 4.5 mm to about 6.5 mm, and the channel depth Dg can be from about 10 mm to about 13 mm.
The rear channel wall 218 and front channel wall 220 define a channel angle β therebetween. In some embodiments, the channel angle β can be between about 10° to about 40°, such as about 16° to about 34°, or about 16° to about 30°. In some embodiments, the rear channel wall 218 extends substantially perpendicular to the ground plane when the club head 2 is in the normal address position, i.e., substantially parallel to the z-axis 65. In other embodiments, such as shown in
A plurality of weight ports 40—three are included in the embodiment shown—are located on the sole portion 14 of the golf club head 2, and are located adjacent to and rearward of the channel 212. As described previously in relation to
In the embodiment shown, the weight ports 40 are located adjacent to and rearward of the rear channel wall 218. The weight ports 40 are separated from the rear channel wall 218 by a distance of approximately 1 mm to about 5 mm, such as about 1.5 mm to about 3 mm. As discussed above, the configuration of the channel 212 and its position near the face plate 18 allows the face plate to undergo more deformation while striking a ball than a comparable club head without the channel 212, thereby increasing both COR and the speed of golf balls struck by the golf club head. As a result, the ball speed after impact is greater for the club head having the channel 212 than for a conventional club head, which results in a higher COR.
In
In some embodiments, the slot 312 has a substantially constant width Wg, and the slot 312 is defined by a radius of curvature for each of the forward edge and rearward edge of the slot 312. In some embodiments, the radius of curvature of the forward edge of the slot 312 is substantially the same as the radius of curvature of the forward edge of the sole 14. In other embodiments, the radius of curvature of each of the forward and rearward edges of the slot 312 is from about 15 mm to about 90 mm, such as from about 20 mm to about 70 mm, such as from about 30 mm to about 60 mm. In still other embodiments, the slot width Wg changes at different locations along the length of the slot 312.
The slot 312 comprises an opening in the sole 14 that provides access into the interior cavity of the body 10 of the club head. As discussed above, the configuration of the slot 312 and its position near the face plate 18 allows the face plate to undergo more deformation while striking a ball than a comparable club head without the slot 312, thereby increasing both COR and the speed of golf balls struck by the golf club head. In some embodiments, the slot 312 may be covered or filled with a polymeric or other material to prevent grass, dirt, moisture, or other materials from entering the interior cavity of the body 10 of the club head.
In the embodiment shown in
The slot 312 formed in the sole of the club head embodiment shown in
In the embodiment shown in
A plurality of weight ports 40—three are included in the embodiment shown—are located on the sole portion 14 of the golf club head 2. A center weight port is located between a toe-side weight port and a heel-side weight port and is located adjacent to and rearward of the channel 312. As described previously in relation to
In the embodiment shown, the weight ports 40 are located adjacent to and rearward of the rear channel wall 218. The weight ports 40 are separated from the rear channel wall 218 by a distance of approximately 1 mm to about 5 mm, such as about 1.5 mm to about 3 mm. As discussed above, the configuration of the channel 212 and its position near the face plate 18 allows the face plate to undergo more deformation while striking a ball than a comparable club head without the channel 212, thereby increasing both COR and the speed of golf balls struck by the golf club head. As a result, the ball speed after impact is greater for the club head having the channel 212 than for a conventional club head, which results in a higher COR.
Three additional embodiments of golf club heads 2 each having a slot 312 formed on the sole 14 near the face plate 18 are shown in
Mass Pads and High Density Weights
In the implementations shown in
As described, desired discretionary mass can be added in the form of a mass pad, such as the mass pad 502 (see
In
In alternative embodiments, a mass pad or other high density weight is added to the body of a golf club by co-casting the weight into the golf club head or a component of a club head. For example, a mass pad or other high density weight can be added to a golf club head by co-casting the mass pad with the golf club head. In some embodiments, the mass pad/high density weight is co-casted using a negative draft angle in order to affix or secure the mass pad/high density weight within the club head body. Moreover, in some embodiments, the surface of the mass pad/high density weight is coated with a thermal resistant coating prior to casting. The thermal resistant coating on the surface of the weight acts as a thermal barrier between two dissimilar materials (i.e., the golf club body material and the material of the high density weight), and prevents any reaction between the molten metal of the club head body and the weight material. The coating also promotes adhesion between the molten metal and the weight by improving wetting of the molten metal on the surface of the weight.
For example, as shown in
The surface of the high density weight 250 is preferably coated with a thermal resistant coating 280, as shown in
As noted above, the thermal resistant coating 280 provides a thermal barrier that prevents the materials contained in the high density weight 250 (e.g., tungsten, iron, nickel, et al.) from reacting with the materials contained in the club head body 10 (e.g., stainless steel alloys, carbon steel, titanium alloys, aluminum alloys, magnesium alloys, copper alloys, or the like) during the co-casting process. These reactions may cause unwanted gaps or other defects to occur, which gaps or defects are inhibited or prevented by the thermal resistant coating 280. In addition, the thermal coating 280 has been observed to improve the wetting of the surface of the high density weight 250 by the molten metal of the club head body 10 during the co-casting process, thereby also reducing the occurrence of gaps or other defects.
A method of co-casting the high density weight 250 and golf club head 10 will be described with reference to
Once coated with the thermal resistant coating 280, the high density weight 250 is embedded in a wax pattern 290 used in an investment casting process. See
The foregoing method may be adapted to include multiple high density weights 250 into one golf club head 10 simultaneously. Moreover, in other embodiments, the high density weight 250 is placed in other locations within the mold or golf club head 10. Unlike other methods for installing high density weights or mass pads, there are no density or mechanical property constraints relating to the materials used for the weights, and no welding, deformation, or pressing of the weight(s) is required for installation. Moreover, the shape and size of the co-casted high density weight 250 may be varied to obtain desired results. For example, whereas the high density weight 250 shown in
Characteristic Time
A golf club head Characteristic Time (CT) can be described as a numerical characterization of the flexibility of a golf club head striking face. The CT may also vary at points distant from the center of the striking face, but may not vary greater than approximately 20% of the CT as measured at the center of the striking face. The CT values for the golf club heads described in the present application were calculated based on the method outlined in the USGA “Procedure for Measuring the Flexibility of a Golf Clubhead,” Revision 2.0, Mar. 25, 2005, which is incorporated by reference herein in its entirety. Specifically, the method described in the sections entitled “3. Summary of Method,” “5. Testing Apparatus Set-up and Preparation,” “6. Club Preparation and Mounting,” and “7. Club Testing” are exemplary sections that are relevant. Specifically, the characteristic time is the time for the velocity to rise from 5% of a maximum velocity to 95% of the maximum velocity under the test set forth by the USGA as described above.
Table 1 summarizes characteristics of two exemplary 3-wood club heads that embody one or more of the above described aspects. In particular, the exemplary club heads achieve desirably low centers of gravity in combination with high mass moments of inertia.
Club heads formed according to the Example 1 embodiment are formed largely of an alloy of steel. As indicated by Table 1 and depending on the manufacturing tolerances achieved, the mass of club heads according to Example 1 is between about 210 g and about 220 grams and the Zup dimension is between about 13 mm and about 17 mm. As designed, the mass of the Example 1 design is 216.1 g and the Zup dimension 15.2 mm. The loft is about 16 degrees, the overall club head height is about 38 mm, and the head depth is about 87 mm. The crown is about 0.60 mm thick. The relatively large head depth in combination with a thin and light crown provides significant discretionary mass for redistribution to improve forgiveness and overall playability. For example, the resulting mass moment of inertia about the CG z-axis (Izz) is about 325 kg-mm2.
Club heads formed according to the Example 2 embodiment are formed largely of an alloy of titanium. As indicated by Table 1 and depending on the manufacturing tolerances achieved, the mass of club heads according to Example 2 is between about 210 g and about 220 grams and the Zup dimension is between about 13 mm and about 17 mm. As designed, the mass of the Example 2 design is 213.8 g and the Zup dimension 14.8 mm. The loft is about 15 degrees, the overall club head height is about 40.9 mm, and the head depth is about 97.4 mm. The crown is about 0.80 mm thick. The relatively large head depth in combination with a thin and light crown provides significant discretionary mass for redistribution to improve forgiveness and overall playability. For example, the resulting mass moment of inertia about the CG z-axis (Izz) is about 302 kg-mm2.
Both of these examples provide improved playability compared to conventional fairway woods, in part by providing desirable combinations of low CG position, e.g., a Zup dimension less than about 16 mm, and high moments of inertia, e.g., Izz greater than about 300 kg-mm2, Ixx greater than about 170 kg-mm2, and a shallow head height, e.g., less than about 46 mm. Such examples are possible, in part, because they incorporate an increased head depth, e.g., greater than about 85 mm, in combination with a thinner, lighter crown compared to conventional fairway woods. These features provide significant discretionary mass for achieving desirable characteristics, such as, for example, high moments of inertia and low CG.
Referring to Table 2, golf club heads with added weight attached mechanically to the sole (e.g., as in
For a sample of five parts, the golf club heads having added weight attached by welding showed an average COR of 0.81 and an average characteristic time (CT) of 241 μs. Also for a sample of five parts, the club heads having added weight attached with screws had an average COR of 0.82 and an average CT of 252 μs.
Simulation results confirmed these empirical findings. In simulated results, a golf club head in which the added weight is mechanically attached, resulting in a flexible boundary, yielded a higher COR than a golf club head in which the added weight was welded to the sole without a flexible boundary.
As noted above, several of the illustrated golf club head designs were modeled using commercially available computer aided modeling software. Table 3 below summarizes characteristics of several exemplary 3-wood club heads that embody one or more of the above described aspects.
As shown in Table 3, Examples A through D describe embodiments of club heads that do not include a slot or channel formed in the sole of the club head. Examples E through J, on the other hand, each include a slot or channel of one of the types described above in relation to
Several golf club head were constructed and analyzed. Table 4 below summarizes characteristics of several exemplary 3-wood club heads that embody one or more of the above described aspects.
As shown in Table 4, each of Examples K through T includes a slot or channel of one of the types described above in relation to
Sole Channel
The following study illustrates the effect of forming a channel in the sole near or adjacent to the face of a fairway wood golf club. Two golf club heads having the general design shown in
From the information presented in Table 5 it is seen that the unfilled channel produces a COR that is 0.005 higher than the filled channel for both heads tested. Note that the mass was kept constant by placing lead tape on the sole of the heads when tested before the epoxy adhesive was introduced into the channel.
The epoxy adhesive is not a perfectly rigid material. For example, the modulus of elasticity of the DP420 epoxy adhesive is approximately 2.3 GPa, as compared to the modulus of elasticity of the stainless steel (Custom 450SS), which is approximately 193 GPa. As a result, the filled channel is still able to deflect during ball impact. This suggests that the increase in CT and COR due to the presence of the channel on the sole of the club head is even greater than illustrated by the data contained in Table 5.
Sole Slot
The following study illustrates the effect of forming a curved slot in the sole near or adjacent to the face of a fairway wood golf club. A Burner Superfast 2.0 fairway wood (3-15°) was used in the study. Five club heads were measured for center face characteristic time (CT) and balance point coefficient of restitution (COR) both before and after machining a curved slot in the sole having the general design shown in
From the information presented in Table 6 it is seen that the club heads had an average CT increase of 22 and an average COR increase of 0.011 after forming a curved slot in the sole of the club head. The slotted club heads proved to be durable after being submitted to endurance testing.
Additional COR testing was performed on Head ID 43563 from Table 6. The testing included measuring COR at several locations on the striking face of the club head. The results are shown below in table 7.
From the information presented in Table 7 it is seen that there was an average COR increase of 0.007 for the locations measured. The most significant increase of 0.017 COR points was at the low face location. This location is the nearest to the slot formed in the sole of the club head, and is therefore most influenced by the increased flexibility at the boundary condition of the bottom of the face.
Comparison of Slot, Channel, and No Slot/No Channel Clubs
The following study provides a comparison of the performance of three golf club heads having very similar properties, with one of the clubs having a channel formed in the sole (e.g., the design shown in
As noted in Table 8, the face thickness of the sample club heads were different, with the channel sole having the thickest face and the regular (no slot, no channel) sole having the thinnest face. It would be expected that the thicker face of the club heads having a channel and a slot (relative to the no slot/no channel sole) would tend to cause the measured COR to decrease relative to the measured COR of the No Slot/No Channel sole. Accordingly, the data presented in Table 8 supports the conclusion that the channel and slot features formed in the identified club heads provide additional sole flexibility leading to an increase in the COR of the club head.
Player Testing
Player testing was conducted to compare the performance of the inventive golf clubs to a current, commercially available golf club. Golf clubs according to Examples K and L were constructed and compared to a TaylorMade Burner Superfast 2.0 golf club. The head properties of these three golf clubs are presented in Table 9 below.
The information in Table 9 shows that the Example K and L clubs include a CG that is located significantly lower and forward in relation to the CG location of the Burner Superfast 2.0 golf club, thereby providing a CG projection that is significantly lower on the club face. The static loft of the inventive club heads are approximately equal to that of the Burner Superfast 2.0 comparison club. Accordingly, changes in the spin and launch angle would be associated with differences in dynamic loft, which is verifiable by player testing.
Head-to-head player tests were conducted to compare the performance of the Burner Superfast 2.0 to the two inventive clubs listed in Table 9. The testing showed that the inventive golf clubs (Examples K and L) provided significantly more distance (carry and total), less backspin, a lower peak trajectory, and higher initial ball speed relative to the Burner Superfast 2.0 fairway wood. All clubs had comparable initial launch angles, and both of the inventive golf clubs (Examples K and L) appeared to generate the same initial ball speed. In both tests, the Example K club head produced approximately 380 rpm less backspin, had more carry, and had more roll out distance than the Example L club head.
The hosel opening 3004 is also adapted to receive a hosel insert 200 (described in detail above), which can be positioned on an annular shoulder 3012 inside the club head. The hosel insert 200 can be secured in place by welding, an adhesive, or other suitable techniques. Alternatively, the insert can be integrally formed in the hosel opening. The club head 3000 further includes an opening 3014 in the bottom or sole of the club head that is sized to receive a screw 400. The screw 400 is inserted into the opening 3014, through the opening in shoulder 3012, and is tightened into the shaft sleeve 3006 to secure the shaft to the club head. The shaft sleeve 3006 is configured to support the shaft at different positions relative to the club head to achieve a desired shaft loft and/or lie angle.
If desired, a screw capturing device, such as in the form of an o-ring or washer 3036, can be placed on the shaft of the screw 400 above shoulder 3012 to retain the screw in place within the club head when the screw is loosened to permit removal of the shaft from the club head. The ring 3036 desirably is dimensioned to frictionally engage the threads of the screw and has an outer diameter that is greater than the central opening in shoulder 3012 so that the ring 3036 cannot fall through the opening. When the screw 400 is tightened to secure the shaft to the club head, as depicted in
The shaft sleeve 3006 is shown in greater detail in
The upper portion 3016 of the sleeve extends at an offset angle 3022 relative to the lower portion 3020. As shown in
As best shown in
As further shown in
Other shaft sleeve and hosel insert configurations can be used to vary the number of possible angular positions for the shaft sleeve relative to the longitudinal axis B.
As can be appreciated, the assembly shown in
Whereas this technology has been described in connection with representative embodiments, it will be understood that it is not limited to those embodiments. On the contrary, it is intended to encompass all alternatives, modifications, combinations, and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.
This application is a continuation of U.S. patent application Ser. No. 15/614,999, filed Jun. 6, 2017, which is a continuation of U.S. patent application Ser. No. 14/575,745, filed Dec. 18, 2014, now U.S. Pat. No. 9,700,769, issued Jul. 11, 2017, which is a continuation of U.S. patent application Ser. No. 13/975,106, filed Aug. 23, 2013, now U.S. Pat. No. 8,956,240, issued Feb. 17, 2015, which is a continuation of U.S. patent application Ser. No. 13/873,128, filed Apr. 29, 2013, now U.S. Pat. No. 8,753,222, issued Jun. 17, 2014, which is a continuation of U.S. patent application Ser. No. 13/469,023, filed May 10, 2012, now U.S. Pat. No. 8,430,763, issued Apr. 30, 2013, which is a continuation of U.S. patent application Ser. No. 13/338,197, filed Dec. 27, 2011, now U.S. Pat. No. 8,900,069, issued Dec. 2, 2014, which claims the benefit of U.S. Provisional Patent Application No. 61/427,772, filed Dec. 28, 2010, all of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61427772 | Dec 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15614999 | Jun 2017 | US |
| Child | 16795266 | US | |
| Parent | 14575745 | Dec 2014 | US |
| Child | 15614999 | US | |
| Parent | 13975106 | Aug 2013 | US |
| Child | 14575745 | US | |
| Parent | 13873128 | Apr 2013 | US |
| Child | 13975106 | US | |
| Parent | 13469023 | May 2012 | US |
| Child | 13873128 | US | |
| Parent | 13338197 | Dec 2011 | US |
| Child | 13469023 | US |
