Method of making a golf club that provides enhanced backspin and reduced sidespin

An improved golf club wherein the surface of the face of the club is substantially flat, which is achieved by surfacing (milling) the club face, and wherein the edges of scoring lines (grooves) are made relatively sharp as a result of the surfacing operation. The sharp groove edges (and milling lines) of the present invention produce enhanced backspin and reduced sidespin when a golf ball is struck, which results in a relatively straight golf ball flight path, notwithstanding a glancing club impact angle. In addition, milling lines that may be formed on the club face are generally parallel to the scoring lines and hence enhance the club characteristics. The present invention also provides for methods of making a golf club that has the above features, including forging and casting methods. In either method, a club is processed to produce generally smooth and finished features with scoring lines formed in the face of the club. After the scoring lines are formed, the club face is surfaced (milled) to produce a flat club face and relatively sharp groove edges at the surface of the club face. The surface of the club face may be milled such that the milling texture or milling marks are generally aligned with the scoring lines. This improves the ball spinning capability of the present club. The shape of the scoring lines is not critical to the performance of the club. Any cross sectional shape may be used, including square, V- or triangular-shaped, or curved shapes. The critical point is that the edges of the grooves adjacent the flat club face are sharp, and a right angle edge is optimum.

BACKGROUND 
The present invention relates generally to golf clubs and manufacturing 
methods therefor, and more particularly, to a golf club that produces a 
relatively straight golf ball flight path notwithstanding a glancing 
impact angle, and hence produces enhanced backspin and reduced sidespin, 
and methods of making such a golf club. 
There has been a great deal of controversy and numerous articles have been 
written regarding golf clubs having "square grooves". Much of the 
controversy deals with the amount of backspin that the club imparts to the 
golf ball when struck. An accomplished player has the ability to produce a 
great deal of backspin on the golf ball, which is readily apparent when 
watching a professional tournament. However, the U.S. Golf Association 
(USGA) has guidelines and specifications that control the depth and 
spacing of grooves in golf clubs that are used by players in its 
tournaments. Consequently, although golf club manufacturers produce clubs 
that have relatively square grooves, they must be manufactured to be 
within the USGA specifications. 
Conventional clubs also cause sidespin when they strike a golf ball. When a 
club strikes a golf ball at a glancing angle relative to the swing path, a 
clockwise or counterclockwise sidespin is imparted to the ball which 
causes the golf ball to fade, slice, draw, or hook, depending upon the 
impact angle. Club manufacturers attempt to design their clubs to minimize 
this effect, and hence to produces a more accurate ball striking club. 
Golf clubs are typically made by forging or investment casting processes. 
In a conventional forging process, a female mold is made having the 
general shape of a desired club. The female mold is placed in a mold base 
of a forging press. A piece of hot metal is placed in the mold, and the 
hot metal is pounded into a desired club shape using the press. This 
produces a club having rough features. Then, a grinding operation is 
performed on the club which produces generally smooth and finished 
features. Scoring lines (grooves) are then cut into the face of the club, 
typically by means of a set of rolling blades. After the scoring lines are 
formed, a second grinding operation is performed to finish forming the 
club. The club is then vibrated to remove residue produced by the scoring 
and grinding operations. The scoring lines are also sandblasted. Finally, 
the club is plated to produce a finished product. 
In a conventional investment casting process, a master male mold is made 
having a desired club shape. Then a female mold is made using the master 
male mold. A wax member is then molded having the desired club shape using 
the female mold. A tree is made using a plurality of wax members, and the 
tree is dipped into a number of vats of ceramic "batter" having different 
size ceramic particles on top which successively coats the wax members 
with layers of ceramic. This results in a tree comprising a plurality of 
wax members captivated by a ceramic shell. The ceramic shell containing 
the plurality of wax members are then steam heated to melt the wax, thus 
leaving a ceramic shell having cavities therein that conform to the 
desired shape of the club. The shell is then heated to substantially the 
same temperature as molten metal that is to be poured into it. After 
heating the shell, molten metal is poured into the shell, and the shell is 
allowed to cool, leaving formed metal clubs in the cavities. The scoring 
lines are formed as part of the molding process. The cast clubs are then 
removed from the shell and each is subjected to a grinding operation to 
produce a desired club shape. The clubs are then vibrated to remove the 
residue from the grinding operation. The clubs are then polished and 
sandblasted to produce the finished product. 
In either of these manufacturing processes, the face of the club that is 
produced is not flat, and in particular, the face has an uneven, wavy, 
cavity filled surface, due to shrinkage of the wax and metal, grinding and 
sandblasting. Also, the grooves (scoring lines) do not have sharp edges, 
in that they are generally rounded at the edges of the surface of the club 
face. 
Accordingly, it is an objective of the present invention to provide a golf 
club that has a club face and groove structure that produces enhanced 
backspin and reduced sidespin when it strikes a golf ball, and hence 
produces a flight path that is relatively straight relative to the impact 
angle of the club on the ball. It is also an objective of the present 
invention to provide methods of making a golf club that produces enhanced 
backspin and reduced sidespin and gear effect when it strikes a golf ball. 
SUMMARY OF THE INVENTION 
The assignee of the present invention has performed considerable research 
into groove shapes and club face design. It has been determined that the 
edge of the grooves (and not the specific groove shape) along with the 
surface flatness of the face of the club, may be designed so as to enhance 
backspin and reduce the sidespin caused by the club when it strikes a golf 
ball. This produces a golf club that has improved performance and more 
accuracy. These two factors may be controlled to produce a golf club that 
causes a golf ball to have a relatively straight flight path after being 
struck by the club. 
The present invention is an improved golf club that has several distinct 
features. First, the surface of the face of the club is made substantially 
flat, which is achieved by precision milling the club face, or by 
surfacing it using other available means. This removes any waviness in the 
surface of the club face that is typically found in conventional clubs. 
Second, the edges of the scoring lines (grooves) are made relatively sharp 
as a result of the surfacing (milling) operation, and they are very sharp 
when compared to grooves of conventional clubs. The sharp groove edges 
cause a struck golf ball to have backspin. Consequently, the struck golf 
ball will have a relatively straight flight path, or trajectory, due to 
the backspin imparted to the golf ball. Thus the slice and hook flight 
paths produced by conventional clubs are substantially reduced. 
Furthermore, the surface of the club is milled such that the milling 
texture or milling marks are generally aligned with the scoring lines. 
This improves the ball spinning capability of the present club. 
The present invention also provides for methods of making a golf club that 
has the above features. One forging process is as follows for a single 
club, although multiple clubs may also be made at the same time using the 
present invention. A female mold is made having the general shape of a 
desired club. The female mold is placed in a mold base of a forging press. 
Hot metal is placed in the mold, and it is pounded into a desired club 
shape using the press. This produces a club having rough club features. 
Then, a grinding operation is performed on the club to produce generally 
smooth and finished features. Scoring lines (grooves) are then cut into 
the face of the club. After the scoring lines are formed, the club face is 
surfaced (milled) to produce a flat club face and sharp groove edges 
adjacent the club face. The surfacing operation may be performed using 
computerized numerical controlled (CNC) milling machines, for example. 
One casting process is as follows that illustrates a process for casting 
several clubs at one time, although a single club may also be made using 
the present invention. A master male mold is made having a desired club 
shape. Then a female mold is made using the master male mold. A wax member 
is then molded having the desired club shape using the female mold. A tree 
is formed using a plurality of wax members, and a ceramic shell is formed 
around the tree. The ceramic shell containing the plurality of wax members 
are then heated to melt the wax, leaving a ceramic shell having cavities 
therein that conform to the desired shape of the club. The shell is then 
heated to substantially the same temperature as molten metal that is to be 
poured into it. After heating the shell, molten metal is poured into the 
shell, and the shell is allowed to cool, leaving formed metal clubs in the 
cavities. Scoring lines are typically formed as part of the molding 
process. The cast clubs are then removed from the shell and each is 
subjected to a grinding operation to produce a desired club shape. Each 
cast club is then surfaced (milled) to produce a flat club face and sharp 
groove edges adjacent the club face. The surfacing operation may be 
performed using CNC milling machines, for example. 
The shape of the grooves (scoring lines) of the golf club of the present 
invention is not critical to the performance of the club. Any groove cross 
sectional shape may be used, including square, V- or triangular-shaped, or 
curved shapes. The critical point is that the edges of the grooves at the 
surface of the club face are sharp, and a right angle edge is optimum. The 
shape of the bottom of the groove is not very relevant to the performance 
of the present golf club. Consequently, any manufacturing process that 
produces such a club face and groove arrangement is satisfactory.

DETAILED DESCRIPTION 
Referring to the drawing figures, FIG. 1 a illustrates a perspective view 
of a golf club 10 (or golf club head 10) made in accordance with the 
principles of the present invention, while FIGS. 1b and 1c are two 
enlarged partial cross sections of the golf club 10 at two stages of 
manufacture. These two cross sectional views represent two points during 
the manufacture of the club 10 and illustrate the improvements provided by 
the present invention. The golf club 10 is comprised of a club body 11 
that has a front face 12 or front surface 12 that is adapted to strike a 
golf ball when the finished golf club 10 is swung by a golfer. A plurality 
of scoring lines 14 (grooves 14) are formed in the front face 12. A shaft 
and grip (not shown) are connected to the club body 11 in a conventional 
manner to complete the finished product. The improvements of the present 
invention deal with the golf club body 11, front face 12, and the scoring 
lines 14. 
Referring to FIG. 1b, which shows the club 10 after it has been molded or 
cast into shape and has scoring lines 14 (grooves 14) formed the front 
face 12 thereof. As can be seen in FIG. 1a, the surface of the front face 
12 is not flat, and in fact the front face 12 is generally wavy. This 
surface finish is typically produces by all conventional manufacturing 
processes. The scoring lines 14 have rounded edges 15 adjacent the front 
face 12. This is generally true irrespective of the shape of the scoring 
lines 14. The scoring lines 14 may be any desired shape, including square, 
V- or triangular-shaped, or curved shapes, for example, and which is are 
shown in FIGS. 3a-3c and described below. 
Referring now to FIG. 1c, the front face 12 of the club 10 has been 
surfaced in accordance with the principles of the present invention, 
typically with a computerized numerical controlled (CNC) precision milling 
machine. The milling, or comparable surfacing operation, produces a 
substantially flat front face 12 of the club 10. This in turn produces 
scoring lines 14 having relatively sharp edges 15 at the front face 12. 
This is clearly shown in FIG. 1b, and is the essence of the present 
invention. 
Referring to FIG. 2, it illustrates the advantages produced by the golf 
club 10 of the present invention. FIG. 2 shows the golf club 10 impacting 
a golf ball 20, and shows several possible orientations and directions of 
travel of the club 10 at the instant of impact, shown by dashed lines and 
directional arrows 21a-21c. Normally, a glancing blow of the club 10 on 
the ball 20 in any direction other than straight causes the ball 20 to 
rotate counter to the direction of impact of the club 10. This is 
indicated by the rotational arrows 22a, 22b. This results in undesired 
rotation of the ball 20 and causes a draw (hook) or a fade (slice) 
depending upon the angle of impact. It has been found that a club 10 made 
in accordance with the principles of the present invention, namely that 
has a flat front face 12 and sharp groove edges 15, does not impart much 
sidespin to the ball 20. The edge of the grooves (and not the specific 
groove shape) along with the surface flatness of the face 12 of the club, 
cause enhanced backspin and reduced sidespin to be imparted by the club 10 
when it strikes the golf ball 20. Consequently, when the golf ball 20 
struck with the present golf club 10 it will have a flight path which is 
generally perpendicular to the club face 12 (shown by arrows 21a-21c), and 
which will not slice or hook relative to this flight path after it leaves 
the club face 12. 
The following is presented to provide a better understanding of the physics 
relating to the improvements provided by the present invention. The flight 
of the golf ball 20 is determined by the interactions of the ball 20 with 
the club face 12 diring impact and by the interaction of the ball 20 with 
the air during flight. Many of the aerodynamic effects on the golf ball 20 
are determined by the spin induced on the ball 20 during impact with the 
club face 12. It is well known that the golf ball 20 is slowed down in the 
air by drag. What is less widely known, but which is no less important, 
relates to the aerodynamic force perpendicular to the ball's flight path 
caused by the spin of the ball 20. This perpendicular force is called the 
Magnus force. The Magnus force can lead to additional lift forces away 
from the ground as well as producing golf ball trajectories that curve to 
the left or right (draw or fade). Hence, the ball spin produced at impact 
with the club face 12 causes the ball trajectory to deviate substantially 
from a simple parabolic path of normal simple projectile motion. 
It is the express purpose of the present invention to provide a golf club 
10 that reduces the lateral Magnus force experienced by the golf ball 20 
during its flight. This is a result of the surfaced club face 12 and sharp 
groove edges 15. The present golf club 10 imparts a higher ratio of 
backspin to sidespin to the golf ball 20, thereby reducing the relative 
and absolute magnitude of the fade or draw effect. 
The grooves and surface finish present in the golf club 10 of the present 
invention reduce golf ball sidespin by changing the fundamental frictional 
interaction of the ball 20 with the club face 12 during impact. The 
coefficient of friction (m) may be increased and given a directional 
characteristic using the golf club 10 of the present invention. That is to 
say, the present golf club 10 enhances the frictional coefficient of the 
ball-club interaction in a way that reduces the ball sidespin, thereby 
reducing the drawing or fading of the ball 20 in flight due to lateral 
Magnus forces, while at the same time causing no adverse effects on the 
desirable backspin imparted to the ball 20. 
For the purposes of completeness, FIGS. 3a-3c show cross sections of 
different groove shapes that may be employed with the golf club 10. The 
shape of the grooves 14 (scoring lines) is not critical to the performance 
of the club 10. Any cross sectional shape may be used, including V- or 
triangular-shaped, square, or curved shapes, as are shown in FIGS. 3a-3c, 
respectively. The critical point is that the edges 15 of the grooves 14 at 
the club face 12 are sharp, and a right angle edge is optimum. However, an 
angle that is not exactly 90 degrees is not absolutely required, in that 
it is the sharp edge and fiat club face 12 that is important. The 
performance of the club 10 would be less than optimum for grooves that are 
not sharp, however. Furthermore, the shape of the bottom of the groove 14 
is not very relevant to the performance of the present golf club 10. 
The golf club 10 may be manufactured using a variety of manufacturing 
processes, including forging and investment casting processes, for 
example. FIG. 4 shows a flow diagram of a first method of making a golf 
club in accordance with the principles of the present invention. The first 
method is a forging method 30 that illustrates forging of a single club 
10. However, it is to be understood that multiple clubs may be forged at 
the same time with the appropriate equipment. A female mold is made having 
the general shape of a desired club (step 31). The female mold is placed 
in a mold base of a forging press (step 32). Hot metal is poured into the 
mold (step 33), and it is pounded into a desired club shape using the 
press (step 34). This produces a club having rough club features. Then, a 
grinding operation is performed on the club 10 which produces generally 
finished features (step 35). Scoring lines 14 (grooves) are then formed in 
the face 12 of the club 10 (step 36). After the scoring lines 14 are 
formed, the club face 12 is surfaced to produce a flat club face and sharp 
groove edges 15 at the surface of the club face 12 (step 37). The 
surfacing operation may be performed using a computerized numerical 
controlled (CNC) milling machine, for example. 
FIG. 5 shows a flow diagram of a second method of making a golf club 10 in 
accordance with the principles of the present invention. The second method 
is an investment casting method 40. The casting method 40 illustrates a 
process for casting several clubs 10 at tone time, although a single club 
10 may also be made using the present invention. A master male mold is 
made having a desired club shape (step 41). Then a female mold is made 
using the master male mold (step 42). A plurality of wax members are then 
molded having the desired club shape using the female mold (step 43). A 
tree is formed using a plurality of wax members (step 44), and a ceramic 
shell is formed around the tree (step 45). The ceramic shell containing 
the plurality of wax members are then heated to melt the wax (step 46), 
leaving a ceramic shell having cavities therein that conform to the 
desired shape of the club 10. The shell is then heated to substantially 
the same temperature as molten metal that is to be poured into it (step 
477). After heating the shell, molten metal is poured into the heated 
shell (step 48), and the shell is allowed to cool (step 49), leaving 
formed metal clubs in the cavities. Scoring lines 14 are formed as part of 
the molding process. The cast clubs 10 with the scoring lines therein are 
then removed from the shell (step 50) and each is subjected to a grinding 
operation to produce a desired club shape (step 51). Each cast club 10 is 
then surfaced (milled) to produce a flat club face and sharp groove edges 
15 at the surface of the club face 12 (step 52). The surfacing operation 
may be performed using a CNC milling machine, for example. It is to be 
understood that the grooves 14 may be formed subsequent to casting, in a 
manner similar to that described with reference to the forging method 30, 
and prior to the surfacing step (step 52). 
Thus there has been described a new and improved golf club that produces a 
relatively straight golf ball flight path notwithstanding a glancing 
impact angle, and hence produces enhanced backspin and reduced sidespin, 
and methods of making such a golf club. It is to be understood that the 
above-described embodiments are merely illustrative of some of the many 
specific embodiments which represent applications of the principles of the 
present invention. Clearly, numerous and other arrangements can be readily 
devised by those skilled in the art without departing from the scope of 
the invention.