US20040132544A1 - Golf club head - Google Patents

Abstract

A golf club driver head comprised of a hollow body shell of a standard golf club driver shape. This shape has a front impact face plate, a bottom sole plate, a top crown shell, a curved rear wall, a heel, a toe, and a cylindrical hosel, which extends from the face, crown, and heel junction to attach to a shaft. This body is composed completely from cast or machined billet magnesium alloy. The body shell thickness is generally thicker than that in equivalent locations of metallic and other alloy driver heads of the same head volume. The face plate is thicker than that in the remainder of the body to provide a lower deflection surface, improve durability, and to maintain a forward center of gravity. The result of such a large head is a much larger hitting sweet spot and corresponding increased driver accuracy and control.

Description

BACKGROUND OF THE INVENTION
• This invention relates to the golf club head of the wood driver type.[0001]
• Golf clubs are generally categorized into four main types, drivers, irons, putters and specialty. The traditional driver was made of wood, so the terminology “wood” has become synonymous with the driver, irrespective of its material composition. The wood drivers were made of solid wood and were typically of volumes 200 cc and smaller. Recent advances in manufacturing methodologies and material science have enabled the invention of drivers comprised of steel, alloy and composite materials. Because of the material properties and evolution of manufacturing (casting, forging and welding techniques and technology), the steel and alloy drivers are fabricated as hollow shells. Subsequently, the heads of wood drivers have evolved into a classic shape that includes a slightly curved impact face plate, a curved sole plate, an upper crown shell, a heel, a to and a rear wall. During the past decade these hollow driver heads have also evolved in volume, from approximately 200 cc to 360 cc, yet maintained the approximate 200 gram mass. The reason for the demand for increasing head volume is a larger impact face plate area and larger sweet spot due to the larger polar moment of inertia. However, the wall thicknesses of steel and titanium alloy heads have also become increasingly thin to match a corresponding increase in volume. The impact face plate for these large steel and titanium heads are now thinner than 0.10 inches and are unable to maintain their form and meet regulatory requirements for coefficients of restitution during impact with the golf ball. This has resulted in reduced control of launch angle at impact as well as non-compliance status labeling by major golf governing organizations.[0002]
• In light of the current manufacturing and material technology, the steel and titanium heads are limited in size to the 300 cc to 360 cc range if it is desired to meet current functional and regulatory requirements.[0003]
SUMMARY OF THE INVENTION
• It is an object of this invention to provide a wood driver golf club head which improves the forgiveness of the off-centered impact and increases the sweet spot through the use of magnesium alloy to increase the volume of the head to the 370 cc to 505 cc range and larger.[0004]
• The present invention comprises a golf club head which is an empty, hollow body shaped in the form of a golf club driver head, the body formed entirely of cast or machined billet magnesium alloy, the body also having a front impact face plate, a bottom sole plate, an upper crown shell, a curved rear wall, a heel, a toe, and a hollow neck extending upwardly from the face/crown/heel junction of the body at a predetermined angle, and the front impact face plate having an average thickness of 0.23 inches (in the 370 cc baseline configuration). The walls of the hollow magnesium body can be made thicker than those of a standard steel or titanium golf club head, because magnesium is approximately 77% lighter than steel, 60% lighter than titanium and 33% lighter than aluminum. This added thickness decreases the face deflection at impact, resulting in a more controlled trajectory. This increased thickness also gives a more solid feel at impact and reduces noise and vibration. The thicker material also provides a boss for the insertion of a more dense material to provide better ballasting and tuning to the individual preference of the player. The head volume can be greater than that of a steel or titanium head because of the lighter material used, resulting in a much larger sweet spot and less face deflection during impact. In the preferred embodiment of the invention, the overall head dimensions can be more than 20% larger than those of the largest steel or titanium driver club head.[0005]
• The impact face plate thickness distribution is integral to the structural integrity of the head during impact with the golf ball. The wall has a vertical thickness bias to the height corresponding with the head's center of gravity. At the cross-sectional plane made by the longitudinal and vertical centerlines, the impact face plate thickness is 0.21 inches, 0.27 inches, and 0.21 inches for the top, middle and bottom respectively (corresponding to T3B, T2B and T1B respectively in drawing[0006]5). This thickness distribution provides the most material at the center of the sweet spot, to decrease the localized face deflection and decrease localized bending stresses. The wall also has a horizontal thickness bias that decreases with distance from the hosel. At the cross-sectional plane made by the longitudinal and horizontal centerlines, the impact face plate thickness is 0.28 inches, 0.27 inches, and 0.21 inches for the heel side, middle and toe side respectively (corresponding to T2A in drawing4, T2B in drawing5, and T2C in drawing6 respectively). This distribution decreases the overall bending and improves the feel at impact.
• The lighter material also provides excess material for ribbing on the backside of the impact face plate. This ribbing is typically 0.25 inches deep and 0.125 inches wide. The base configuration is three vertical ribs, the first rib located in the middle of the impact face plate with the remaining two[0007]ribs1 inch on the left and right (drawing10). The alternative “web” ribbing adds more ribs to create a grid of triangular patterns (drawing11). This ribbing provides more bending strength and reduces material stress at impact.
• Because the forward portion of the bottom sole plate can come into direct contact with the ball and/or the ground, the plate is thicker in the forward location relative to that of the aft portion of the plate. The top crown shell is similarly proportioned because with severe miss-struck shots, it can directly impact the ball. The back wall is as thin as the casting or machining technology will allow.[0008]
• There are two locations on the head that allow for ballast material. This ballast material can be lead, tungsten or other malleable, dense material. The first ballast location is in the hosel, which is a standard location in the inner hosel below the tip of the shaft. The second ballast location is in the toe, where there is a boss that can be drilled and ballast material inserted. Varying amounts of ballast material such as tungsten or lead can be added or removed to increase or decrease the center of gravity (CG) height of the head. These two ballasting locations are in the forward part of the head. This allows the location of the head CG to be adjusted vertically and horizontally, while maintaining a forward location. This ballasting also provides a spectrum of swingweights necessary to satisfy the requirements of golfers based on their skill and strength level, without significantly altering the characteristics or weight distribution of the head.[0009]
DESCRIPTION OF THE DRAWINGS
• The invention will be graphically described from the following drawings. These drawings were produced from the detailed three-dimensional mathematical computer aided design model that was used to fabricate actual driver head components. Drawings[0010]1-3 will give the basic views of the head while drawings4-11 show the corresponding cut sections and drawings. The vertical, horizontal and longitudinal centerlines intersect at the head center of gravity:
• [0011]Drawing1 is a front elevation view of a golf club driver head according to the baseline configuration of the invention;
• [0012]Drawing2 is the left side elevation view of the head;
• [0013]Drawing3 is a top plan view of the head;
• [0014]Drawing4 is a cross-section on the lines A-A ofDrawing3;
• [0015]Drawing5 is a cross-section on the lines B-B ofDrawing3;
• [0016]Drawing6 is a cross-section on the lines C-C ofDrawing3;
• [0017]Drawing7 is a cross-section on the lines D-D ofDrawing3;
• [0018]Drawing8 is a cross-section on the lines E-E ofDrawing3;
• [0019]Drawing9 is a cross-section on the lines F-F ofDrawing3;
• [0020]Drawing10 is a cross-section on the lines E-E ofDrawing3 which shows the baseline rib configuration;
• [0021]Drawing11 is a cross-section on the lines E-F ofDrawing3 which shows the alternative rib configuration.
DESCRIPTION OF THE PREFERRED CONFIGURATION
• [0022]Drawings1,2,3 describe the golf club driver head according to the baseline configuration of the present invention. The head can be described as a hollow shell body of cast or machined magnesium alloy, having a frontimpact face plate1 anupper crown shell2, a bottomsole plate3, aheel4, atoe5, a rearcurved shell6, and ahollow hosel7 extending from the face/crown/heel junction at a specified angle for the insertion of the golf club shaft (not illustrated). The head has the shape of a conventional golf club driver head, but is of larger dimensions than conventional large-headed drivers.
• The size of the head ranges from 370 cc to 505 cc and greater, which is larger than that of a standard titanium or steel driver head producing a corresponding increase in the sweet spot and reducing the number of miss-struck shots. The face thickness is increased to improve durability and decrease localized face deflection, which increases the predictability and consistency of the shot. In addition to a larger head and sweet spot, the weight of the 370 cc baseline head is about 185 grams, which is less than that of a standard titanium head. This weight allows for the addition of up to 20 grams ballast weight in the hosel and the toe of the head to allow for horizontal and vertical adjustment of the center of gravity. In the 370 cc baseline configuration of the invention, the impact face plate is 2.25 inches high and 5 inches wide.[0023]
• [0024]Drawings4,5 and6 illustrate the variation of thickness of the impact face plate over its area for the 370 cc baseline configuration. The impact face plate has an average thickness of 0.23 inches, whereas the remainder of the body has a wall thickness between 0.09 inches and 0.15 inches. Thus, the impact face plate contains the most material of any wall and the weight and center of gravity is closer to the front of the head, which improves the ball-striking properties. The impact face plate is not of uniform thickness but is generally thicker in the sweet spot corresponding to the CG height and head center. This wall contour is designed to decrease the localized material stresses, improve durability, and move the center of gravity closer to the front of the striking face. The various thickness dimensions indicated indrawings4,5,6 in the baseline configuration of the invention are given below in inches:

  370 cc Baseline Configuration (inches):

  T1A = 0.235	T1B = 0.220	T1C = 0.200
  T2A = 0.280	T2B = 0.270	T2C = 0.235
  T3A = 0.235	T3B = 0.220	T3C = 0.200
  T4A = 0.105	T4B = 0.125	T4C = 0.120
  T5A = 0.110	T5B = 0.115	T5C = 0.120
  T6A = 0.120	T6B = 0.120	T6C = 0.120

• [0025]

  505 cc Version (inches):

  T1A = 0.188	T1B = 0.176	T1C = 0.160
  T2A = 0.224	T2B = 0.216	T2C = 0.188
  T3A = 0.188	T3B = 0.176	T3C = 0.160
  T4A = 0.100	T4B = 0.095	T4C = 0.090
  T5A = 0.090	T5B = 0.090	T5C = 0.090
  T6A = 0.090	T6B = 0.090	T6C = 0.090

• To reduce stresses at the inside corners, radius fillets are applied. As a practical precaution to cutting or scraping items the club may incidentally come into contact with, the outer corners are sanded or ground to a radius. The front curvature of the impact face plate is relatively large over its entire area to provide a large striking area. This further increases the sweet spot and results in a head that produces improved accuracy for miss-struck shots. The maximum thickness of 0.28 inches (in the 370 cc baseline configuration) is located at the horizontal centerline of the striking face on the hosel side, while the minimum thickness is 0.09 inches (in the 370 cc baseline configuration) at the back wall.[0026]
• [0027]Drawings7,8,9 ate the horizontal cut-sections D, E, F corresponding to the forward, middle and rear respectively. These drawings show the hosel and the wall thickness of the crown, sole, heel and toe. Drawing7 cuts through the hosel, showing the following:
• Interior Threads: For the increased retention of the shaft to the[0028]head8
• Interior Chamfer: For the reduction of the point contact load of the end of the hosel with the[0029]shaft9
• Weight Ballast Compartment: For the addition of a standard lead weight located at the tip of the[0030]shaft10
• [0031]Drawing7 also shows the wall thickness of the toe to be thicker than is structurally required during impact, but this material acts as a boss for the insertion of a soft malleable metal extrusion or screw made from material such as tungsten, brass or lead.
• [0032]Drawings7,8 and9 show how the wall thickness of the sole, crown, heel and toe tapers from front to back. This tapering maintains the forward location of the center of gravity of the head as well as reduces the overall head weight to allow for a larger total volume of the head.
• [0033]Drawings10 and11 show the baseline and alternate configuration respectively of the ribbing behind the front impact face plate. These ribs provide added strength to the face to reduce total deflection upon impact resulting in increased control on miss-struck shots.
• By manufacturing the hollow shell of the golf club head completely of lightweight magnesium or magnesium alloy, the weight distribution can be improved by increasing the overall impact face plate thickness and optimally varying the thickness. This also moves the center of gravity forward, closer to the impact face plate. In addition, the total volume of the head can be increased, which results in a corresponding increase in the sweet spot and improved control and distance with miss-struck shots. The wall thickness over the entire body can be increased, resulting in increased structural rigidity and reduced vibration upon impact with the golf ball.[0034]
• The two locations of weight adjustment in the toe and the hosel allow for the adjustment of the CG location in the vertical, horizontal and longitudinal direction in addition to providing swing weights to accommodate the personal requirements of golfers of every power and skill level.[0035]
• Though the baseline and alternative configurations of the invention have been described by explicit detail, it will be understood by those in the golf industry that alternative configurations of and modifications to the disclosed invention still are within the scope of the invention, which is defined by the following claims:[0036]

Claims (14)

I claim:

1. A golf club head, comprising:

(a) a complete body, the body having a front impact face plate, a bottom sole plate, a top crown shell, a curved rear wall, a heel, a toe, and a hollow hosel which extends upward from the face/crown/heel junction at a predetermined angle for attaching said golf club head to a shaft;

(b) said body and hosel being formed entirely of cast or machined billet magnesium alloy;

(c) said front impact face plate having a thickness which varies across its area and is thickest at the center of the impact face plate while generally thinnest around the periphery of the impact face plate;

(d) said impact face plate being thicker at the heel area than the toe area while having no bottom versus top thickness bias.

2. The golf club head as inclaim 1, wherein the body is cast or machined in two parts. The first part comprises the complete shell of the head with the exception of which the bottom sole plate has an opening extending over the majority of its surface. The second part is a separate sole plate, which is welded flush around the periphery of the bottom opening of the first part.

3. The 370 cc baseline golf club head as claimed inclaim 1, wherein the thickness of the impact face plate is between 0.200 and 0.280 inches (0.160 inches and 0.224 inches respectively for the 505 cc version).

4. The 370 cc baseline golf club head as claimed inclaim 1, wherein the wall thickness at the center of the impact face plate is approximately 0.270 inches (0.216 inches for the 505 cc version).

5. The 370 cc baseline golf club head as claimed inclaim 1, wherein the wall thickness at the side edges of the impact face plate is in the range from 0.200 to 0.280 inches (0.160 inches and 0.224 inches respectively for the 505 cc version).

6. The 370 cc baseline, golf club head as claimed inclaim 1, wherein the wall thickness at the lower and upper edges of the impact face plate ranges from 0.200 to 0.235 inches (0.160 inches and 0.188 inches respectively for the 505 cc version).

7. The 370 cc baseline golf club head as claimed inclaim 1, wherein the wall thickness of the top crown shell is between 0.10 and 0.14 inches (0.09 inches and 0.11 inches respectively for the 505 cc version).

8. The 370 cc baseline golf club head as claimed inclaim 1, wherein the thickness of the sole plate is between 0.12 and 0.20 inches (0.09 inches and 0.09 inches respectively for the 505 cc version).

9. The 370 cc baseline golf club head as claimed inclaim 1, wherein the thickness of the toe is between 0.12 and 0.47 inches (0.10 inches and 0.37 inches respectively for the 505 cc version); the front most thickness of the toe being 0.47 (0.37 inches for the 505 cc version) to provide boss material for heavy material like lead or tungsten to be inserted.

10. The 370 cc baseline golf club head as claimed inclaim 1, wherein the thickness of the back wall is between 0.11 and 0.12 inches (0.09 inches and 0.09 inches respectively for the 505 cc version).

11. The 370 cc baseline golf club head as claimed inclaim 1, wherein the thickness of the heel is between 0.11 and 0.14 inches (0.09 inches and 0.10 inches respectively for the 505 cc version).

12. The golf club head as claimed inclaim 1, wherein the outside diameter of the hosel is approximately 0.66 inches and has a 0.337-inch diameter hole for insertion of a standard wood golf shaft. Standard 45-degree hosel chamfer and inner channels (Five V-channeled rings, cut 0.01 inches deep and placed 0.22 inches apart). Starting from about the horizontal centerline to the bottom of the heel, the hosel outside diameter tapers from 0.66 inches to approximately 0.50 inches respectively.

13. The golf club head as claimed inclaim 1, wherein the face has three ribs, one placed vertically in the center of the face and the others each 1 inch (1.25 inches for the 505 cc version) on each side of this central rib. The ribs are of 0.125 inches thickness with about a 0.25 inches (0.30 inches for the 505 cc version) depth.

The head is formed completely form a light weight alloy magnesium metal, which is at least 77% lighter in weight than steel, 60% lighter than titanium and 33% lighter than aluminum:

MagnesiumDensityDensity%Materiallb./in.{circumflex over ( )}3lb./in.{circumflex over ( )}3LighterSteel0.2840.06677%Titanium0.1640.06660%Aluminum0.0980.06633%

The front impact face plate has an average thickness of approximately two times that of the remainder of the head.

The thickness of the impact face plate varies from its outer perimeter towards its geometrical center; the impact face plate is thickest at its center and generally thinner around the periphery of the impact face plate.

14. The golf club head as claimed inclaim 1, wherein the inner corners have rounded fillets and the outer corners are rounded.

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