Patent Application
20140073447
The present invention generally relates to sets of iron golf clubs, and more particularly, to sets of iron golf clubs that provide a consistent ball flight peak height and consistent ball flight angle of descent.
In conventional sets of “iron” golf clubs, each club includes a shaft with a club head attached to one end and a grip attached to the other end. The club head includes a face for striking a golf ball. The angle between the face and a vertical plane is called “loft.” In general, the greater the loft is of the golf club in a set, the greater the launch angle and the less distance the golf ball is hit.
A set of irons generally includes irons that are designated number 3 through number 9, and a pitching wedge. The iron set is generally complimented by a series of wedges, such as a pitching wedge, a lob wedge, a gap wedge, and/or a sand wedge. Sets can also include a 1 iron and a 2 iron, but these clubs are generally sold separate from the set. Each iron has a shaft length that usually decreases through the set as the loft for each club head increases, from the long irons to the short irons. The length of the club, along with the club head loft and center of gravity impart various performance characteristics to the ball's launch conditions upon impact. The initial trajectory of the ball generally extends between the impact point and the apex or peak of the trajectory. In general, the ball's trajectory for long irons, like the 3 iron, is a more penetrating, lower trajectory due to the lower launch angle and the increased ball speed off of the club. Short irons, like the 8 iron or pitching wedge, produce a trajectory that is substantially steeper and less penetrating than the trajectory of balls struck by long irons. The highest point of the long iron's ball flight is lower than the highest point for the short iron's ball flight. The mid irons, such as the 5 iron, produce an initial trajectory that is between those exhibited by balls hit with the long and short irons.
One of the major problems for players is that the lower launch angle of the golf balls hit with long irons leads to a low angle of descent. Because the ultimate peak height is less and the ball is traveling at a faster pace, the angle of descent can be very low. Thus, the ball can hit near a targeted area and then continue to roll for an extended distance. With short irons, players are generally able to hit the ball close to the intended target and the ball will remain close to the point of impact after it hits the ground. It would be desirable to have all the club heads in a set produce a relatively consistent peak height and, particularly, a more consistent angle of descent through the set. This would allow golfers to improve their performance and confidence.
In accordance with the present invention, a set of golf clubs is disclosed. The set includes at least first, second and third golf clubs that are comprised of a club head attached to a shaft and grip. An improvement is that the set is configured such that the angle of descent of a golf ball hit by each of the clubs in the set is substantially more constant than in the past. Furthermore, the set is preferably configured such that the maximum height of the ball trajectory for each of the clubs is greater than about 30 yards and is relatively constant through the set.
Within the set, the first, second and third golf club heads each comprise a heel, a toe, an upper surface, a lower surface, a hosel and a front face for striking the golf ball. The first club is a long iron, comprising a first loft angle (LA1) of between about 15 and 25 degrees and generally has a longer shaft. The second golf club is a mid iron comprising a second loft angle (LA2) of between about 26 and 36 degrees. The third golf club is a short iron comprising a third loft angle (LA3) of between about 37 and 47 degrees. In most circumstances, the long irons include the 2-4 irons within a set, the mid irons include the 5-7 irons and the short irons include the 8-Pitching Wedge.
After studying many PGA Tour players, the inventors discovered that the maximum height of each club in a set drastically decreased for long irons and the angle of descent was very low for long irons. According to the data obtained, prior art clubs could be characterized as having a angle of descent (AD) described by a best fit linear equation according to the following formula:
AD=m(LA)+z
wherein LA is the iron loft angle, mpa is about 0.7 and zpa is about 22 degrees. Thus, a preferred embodiment of the present invention can be characterized by the same equation wherein mI is less than about 0.5 and zI is greater than about 30 degrees. More preferably, mI is between about 0.1 and 0.4 and, most preferably, mI is between about 0.2 and 0.4. Further, in the preferred set of golf clubs according to the present invention, zI is between 35 and 45 degrees, and more preferably, zI is about 35-40 degrees.
Furthermore, in a preferred embodiment of the inventive set of irons, the maximum trajectory height for the first, second and third golf clubs are all between about 30 and 35 yards. The distance at which each club obtains the maximum height varies through the set, but is inversely proportional to the iron loft angle. In a most preferred set, the maximum trajectory height for the first, second and third golf clubs are substantially constant.
Still further, in a preferred embodiment of the inventive set of irons, the first center of gravity height for a long iron is less than the second center of gravity height of the mid iron by at least 0.1 inch and the second center of gravity height is less than the third center of gravity height of the short iron by at least 0.1 inch. Preferably, the lower surface of the first golf club is formed from a material have a specific gravity of greater than 10 g/c and/or a portion of the hosel of the first golf club is comprised of a material having a specific gravity of less than 7 g/cc.
Within a set of golf club irons according to the present invention, each of the first, second and third golf clubs has a shaft axis and a distance from the center of gravity of each club to the shaft axis. In one embodiment, this distance is approximately constant throughout the set. In another embodiment, this distance is progressive throughout the set such that the distance is inversely proportional to the loft angle such that as loft angle increases, the distance between the center of gravity and the shaft axis decreases. Also, the first golf club has a first offset, the second golf club has a second offset and third golf club has a third offset and, preferably, the first offset is less than 0.15 inch and greater than the second offset and the second offset is greater than the third offset. Even more preferably, the first offset is less than about 0.14 inches.
As illustrated in the accompanying drawings and discussed in detail below, the present invention is directed to a set of iron-type golf clubs, wherein the clubs create a ball flight that ends in a more consistent angle of descent AD throughout the set. Referring to
Club head 10 includes, generally, the hosel 20, a striking or hitting face 16 and a back portion that can be cavity backed or muscle backed as is well known in the art. The club head also has a heel 12, a toe 14, a top line 22 and a sole 24. As is well know in the art, the club head 10 and hosel 20 are designed such that the club has a center of gravity CG that is located between the toe 14 and heel 12.
As shown in
In accordance with an aspect of the present invention, the inventive iron golf clubs are designed to have substantially the same carry distance as conventional iron golf clubs. Each inventive iron golf club is designed to hit golf balls a prescribed distance in the air, and to stop on the green or fairway in a predictable manner.
Using actual golf ball flight data obtained using a TrackMan™, the carry distance, maximum ball height and angle of descent can be measured. First, 2011 Titleist Pro V1x golf balls are hit using a Golf Labs™ hitting machine set up to strike the golf ball at typical PGA Tour speeds. For example, and for purposes of this application, a 3-iron is set up to hit the ball at a club head speed of 97 mph and an attack angle of −5 degrees, a 5-iron is set up to hit the ball at a club head speed of 95 mph and an attack angle of −6 degrees and an 8-iron is set up to hit the ball at a club head speed of 92 mph and an attack angle of −7.5 degrees. The remainder of the clubs within the set can be tested by interpolating and extrapolating from these points. After the ball is hit, the TrackMan™ measures the flight of the ball, such that the ball height and angle of descent can be obtained. Next, adjustments are made to the irons in the set to adjust the flight parameters to reach the target performance. For example, if the data suggest that the maximum ball height for a particular club is lower than the target height, then adjustments are made to the club to increase the ball flight height, such as increasing launch angle or ball spin. Potential adjustments to the irons include, but are not limited to, the following factors and combinations thereof:
i. increasing/decreasing shaft length to adjust club head speed and initial ball speed;
ii. increasing/decreasing static loft angle to adjust launch angle and backspin;
iii. adjusting the flexing characteristics of the shaft to adjust club head speed, initial ball speed and spin;
iv. adjusting the location of the center of gravity, CG, of the club head, including lowering the CG and/or moving the CG further aft of the hitting face, to adjust trajectory of the ball; and
v. varying groove geometry and/or the surface roughness to adjust the amount of ball spin.
U.S. Pat. No. 7,699,716 outlines specifically what the PGA Tour speeds and launch conditions are in the specification and the entire specification provides a detailed discussion of club design characteristics that can be manipulated to achieve particular distances and flight characteristics through a set. In other words, while the '716 patent teaches away from designing a set of irons such that the flight height remains more consistent in a set, as evidenced by
Referring to
Referring to
In the first embodiment, the club heads are cast so that the club heads are integral and formed of one material. The club heads can be cast or forged from a material such as 431 Stainless Steel or other materials including alloys well known by those of ordinary skill in the art of making clubs. The clubs can also be formed in one or more parts that are joined by various methods, for example but not limited to welded, silver soldered, brazed, or mechanically fastened with fasteners.
These and other aspects of the present invention may be more fully understood with reference to the following non-limiting example which is merely illustrative of a preferred embodiment of the present invention set of golf clubs, and is not to be construed as limiting the invention, the scope of which is defined by the appended claims.
Tables I and II provides exemplary, non-limiting dimensions for the various measurements of clubs discussed in reference to
Referring to
AD=m(LA)+z
Where m is less than 0.5 and, preferably, between 0.1 and 0.4. Most preferably, m is between 0.2 and 0.4. z is greater than 30 degrees and preferably between 35 and 45 degrees. Most preferably, z is about 35-40 degrees. Thus, the angle of descent will be greater for the short irons that have higher loft angles. It is also understood that the short irons impart greater spin on the golf ball than long irons. Thus, the ground roll for short irons and long irons according to the present invention will differ significantly.
As set forth in Table I, the center of gravity locations within the set should be set to assist with the creation of the preferred flight paths. Option can include, for example, lowering the center of gravity of the long irons by forming the lower surface, or sole, of the long irons from a material have a specific gravity of greater than 10 g/cc such as tungsten or a tungsten alloy. Additionally, the hosel of the long irons can be comprised of a material having a specific gravity of less than 7 g/cc such as titanium, aluminum or alloys thereof. Conversely, high specific gravity materials may be employed within the topline portion of the short irons to raise the center of gravity. Another way to accomplish the progression of the center of gravity through the set is to employ a progressive face insert. Referring to
Another aspect of the preferred embodiment is to have a consistent feel within the set. Thus, the swing weights of the irons may be constant through the set. Furthermore, the distance from the center of gravity to the shaft axis can be approximately constant through the set or progress through the set inversely to the loft.
AD=m(LA)+z
And m is equal to 0.4 and z is equal to 35 degrees compared to the prior art 101. This demonstrates the drastic difference in the angle of descent between the long irons of the present invention and the prior art. For example, the 3 iron according to the embodiment in
While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. The sets of clubs disclosed can include a series of wedges, each with a different loft, such as pitching, lob, gap and sand wedges. The features disclosed to vary the angle of descent, as discussed above, can be used in different combinations. Therefore, it will be understood that the appended claims are intended to cover all modifications and embodiments which would come within the spirit and scope of the present invention.
