Golf club head controlling golf ball movement

Details Golf club head controlling golf ball movement Golf club head controlling golf ball movement

1998-10-09

2001-02-20

Passaniti, Sebastiano (Department: 3711)

Games using tangible projectile

Golf

Club or club support

C473S342000, C473S345000, C473S349000

Reexamination Certificate

active

06190267

ABSTRACT:

BACKGROUND
Field of Invention
Clubhead Heel Weight
The present invention relates generally to golf clubs and specifically to peripherally weighted golf clubs. In the past 100+ years of golf club design evolution, several key parts of the golf club have moved to today's commercial design practices and accepted principles of operation. Lengths of the clubs have standardized (ie the most common Driver is 43 to 45 inches in length), weight of the clubhead itself have stabilized (ie Driver heads generally weigh 190-210 grams), weight of the golf shaft has been reduced (ie graphite construction shafts for woods are in the 50 to 75 grams weight), the end result is construction of clubs that meet the needs of the majority of golfers, both men and women, young and old.
One facet of a golf club that has been advertised, discussed, argued about, and generally misunderstood is the ‘Sweet Spot’ of the clubhead itself. In the literature on golf club construction and performance this ‘Sweet Spot’ is described mainly as a single point where the maximum amount of energy is transferred to the golf ball when it is struck during the golf swing. Contact at this point is also considered optimum because no sideways spin motion is imparted to the ball. This results in the golfer hitting a straighter shot. This is the goal of all golfers. The problem here arises from the fact that all golf club manufacturers describe the ‘Sweet Spot’ as nothing but a ‘spot’ of unknown size on the face of the clubhead. When a manufacturer advertises that the ‘Sweet Spot’ on his club is larger, it is never defined how much larger, or how big it is.
The largest, most recent development in golf club design over the past 15-20 years was the increase in rotational inertia of the clubhead itself. This was accomplished with the development of the metal (hollow) wood clubs and the irons with weight moved to the edges around the face itself. It has been believed that this increase in rotational inertia about the face center-point has increased the ‘Sweet Spot’. This improved playability of the clubs resulting in straighter shots with more control of the results by the golfer.
The development of increased rotational inertia had a part in increasing the accuracy of the golf shots. However the improvement was not in the form most commonly believed in the industry. The ‘Sweet Spot’ has a 2 dimensional characteristic on the club face. It is the result of space between the Center-of-Gravity (CG) of the clubhead itself, independent of the shaft which is attached, and the physical phenomena known as the Center-of-Percussion (COP).
FIG. 11
shows the location of the COP
48
relative to the CG
32
of a clubhead
28
attached to a golf shaft
192
. Center-of-Percussion effects are described in the literature most commonly in the Free-Body Diagram form as shown in FIG.
12
. This Figure shows a body of any shape rotating about pivot axis
2
that results in formation of a COP
48
, a fixed distance
182
(Sweet Spot area) past the CG
32
, due to applied force F, as shown. The distance from pivot axis
2
to the CG
32
is the length
176
. There is no reactive force at the pivot axis when the force passes directly through to the COP.
In the referenced literature MECHANISM AND MACHINE THEORY by J. S. Rao, (paragraph 12-2), THEORY OF MACHINES AND MECHANISMS, by J. E. Shipley and J. J. Uicker, Jr. (paragraph 13-7), and KENT'S MECHANICAL ENGINEERS HANDBOOK, Design and Production Volume, 12th Edition (pages
7-26
to
7-27
), this physical condition of forces acting upon a body that pivots about a fixed axis, will pass through the COP, is described mathematically. This results in no reactive forces being generated at the pivot axis if the applied force passes through the COP itself and not the CG. The same analysis for forces acting through the Center-of-Gravity, when translation motion is present, is described in these same references. The forces applied in translation have the same effect acting through the CG, as does the rotation forces for the COP described above. Contained within the reference, COLLEGE PHYSICS, by F. W. Sears and M. W. Zemensky, (pages 213 through 220), are all of the relationships between Center-of-Gravity and Center of Percussion. How the COP and CG produce the true ‘Sweet Spot’ is discussed in this text.
From the referenced engineering textbooks the following equations apply to determining the various parameters (like distance to COP, rotational inertia of any solid body, pendulum period of oscillation, and etc.), and can be used in new golfhead design.
Definitions
J=Rotational Inertia about any pivot axis
LCG=Distance to Center-of-Gravity from any pivot axis
LCOP=Distance to Center-of-Percussion from same pivot axis
T=Period of Oscillation for any solid body swinging from any pivot axis (with small amplitudes of movement side-to-side)
G=Acceleration of Gravity (386.4 In/Sec)
Pi=Constant 3.1614 used in Geometry and Trig Analysis
**=Mathematical Square Function
*=Mathematical Multiply Function
W=Weight of Clubhead
Equations of Interest
J=(T**2)*W*LCG/(4*Pi**2)(in-lb-sec**2)  Equation A
LCOP=J*G/(W*LCG)(in)  Equation B
It should be noted that the Rotational Inertia (J) of any shaped body can be determined by (1) swinging the part around a pivot axis of interest, (2) measuring the LCG and W of the body, and (3) calculating it's J from the Equation A above. On the other side of the coin, if the Rotational Inertia (J) and Weight (W) are estimated reasonably close, and the Distance to CG (LCG) can be closely approximated; then the Distance to the resulting COP (LCOP) can be determined by Equation B above.
After a prototype clubhead is built the resulting location of the COP can then be measured accurately and determined by the
2
C relationship that follows. The only parameter needed is the Pendulum Period of Oscillation (T). This physical relationship was developed in the U.S. Patent Record first in U.S. Pat. No. 5,269,177, Miggins, et al, (1993), and the literature references (for this patent). One can determine LCOP by making this calculation as follows:
LCOP=9.785*(T**2)(inches)  Equation C
Or,
LCOP=24.81*(T**2)(centimeters)
In a golf club making high velocity contact with a golf ball there are both translation and rotation motion occurring at the same time. With reference to
FIG. 13
where a top view of a golfhead making contact with a golf ball is shown, one can see both translation
3
and rotation
4
due to Force FB. Both motions are occurring at the same time. The Principle of Superposition applies in the golf club was confirmed with laboratory analysis, and it is described in detail in DYNAMICS OF MACHINERY, by A. R. Holowenko, (1955), from a mechanical application of forces viewpoint, and in INTRODUCTORY CIRCUIT ANALYSIS, by S. I. Pearson and G. J. Maler, (1965), from an voltage (electrical form of force) analysis viewpoint. The important result of interest in the golf club is how the CG and COP share in the handling of an applied impact force FB that is made with ball contact during the golf swing.
When the point of contact occurs between the two centers (CG and COP) they each take an appropriate share of the load depending upon the relative distance to each center from the point of contact. With respect to the body of the clubhead the effects of the ball contact force are absorbed by each center producing a moment about each center. When the force is applied between the two centers then the resulting moments will cancel each other out.
FIG. 14A
shows how the distribution of the absorbed force FB is distributed between the CG
32
and COP
48
.
These centers act as anchors (in the Percussive sense) where the applied force is absorbed (momentarily) as reactive forces FR(COP)
7
and FR(CG)
8
. The magnitude of each reaction force is dependent upon the distance from the applied force location on the clubhead face. The closer a reaction force is to the applied force,

Affiliated with

Also associated with

Rating

Golf club head controlling golf ball movement does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Golf club head controlling golf ball movement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Golf club head controlling golf ball movement will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2585492