Golf club head

A golf club head having improved weight distribution comprising an integral hollow metal body with a bottom wall including a cavity recessed inwardly of the body throughout an extended area which lies rearwardly of the front striking face and inwardly of the heel and toe such that the ground engaging sole area of the head comprises a front rail portion adjacent the front striking face and side rail portions joined to the front rail portion and extending toward the rear wall. The side rail portions disposed between the center of percussion and the heel and toe areas. The recessed cavity has a size and depth sufficient to result in a concentration of club head weight in the area surrounding the center of percussion and to produce an elevation in the center of gravity of the head relative to the ground engaging sole area.

BACKGROUND OF THE INVENTION 
The subject invention is directed to an improved golf club head 
construction. 
The invention is especially suited for incorporation in a cast metal golf 
head and will be described with particular reference thereto; however, 
heads embodying the invention could be formed using many known techniques. 
Currently, many golf club heads of the "wood" category are manufactured 
from metal using investment casting techniques. These club heads are 
generally hollow shells with perimeter weighting. That is, the weight of 
the head is concentrated in the outer peripheral shell surface. 
Although perimeter weighting has resulted in improvement in club 
performance as compared to earlier solid body club designs, it is believed 
that even further performance improvements can result from more desirable 
club head weight distribution. 
SUMMARY OF THE INVENTION 
The subject invention provides a metal golf club head which can produce 
increased effectiveness and accuracy because of its unique weight 
distribution. In the subject invention, the design is such that weight is 
removed from the center sole area and redistributed to concentrations in 
the heel and toe area. In a preferred embodiment, the removed weight is 
positioned between the heel and toe areas and the center of percussion 
respectively. In addition, the design raises the center of gravity of the 
club head which is believed to create more roll on the ball after impact 
with the ground and, consequently, more total ball distance results. 
In accordance with the subject invention, a golf club head of the general 
form under consideration comprises an integral hollow metal body with a 
front striking face, an upper wall, a rear wall, a heel, a toe, a bottom 
wall forming a sole, and a hosel extending upwardly at a predetermined 
angle from the heel of the body for attaching the head to a shaft. An 
improved weight distribution results from a recessed cavity formed 
inwardly of the body throughout an extended area rearwardly of the front 
striking face and inwardly between the heel and toe such that the ground 
engaging sole area of the head comprises a front rail portion adjacent the 
front striking face and side rail portions joined to the front rail 
portion. The side rail portions extend toward the rear wall adjacent the 
heel and toe. Alternatively, the side rail portions are disposed behind 
the front striking face region adjacent the center of the club head, i.e. 
the preferred ball impact zone, and inward of the extreme heel and toe 
areas. This increases weight in the area surrounding the ball impact zone 
(center of percussion) helping off-center hits. Preferably, the side rails 
are sufficiently massive to result in added club head weight between the 
center of percussion and the heel and toe areas increasing the "sweet 
spot". In either embodiment, the side rails also help form a recessed 
cavity having a size and depth to produce an elevation in the center of 
gravity of the head relative to the ground engaging sole area. 
Preferably, and in accordance with a more limited aspect of the invention, 
the side rail portions extend generally perpendicular to the front 
striking face and define with the front rail portion a ground engaging 
section generally U-shaped in plan view. 
In accordance with a more limited aspect of the invention, the recessed 
portion is located centrally of the bottom wall and is generally aligned 
with the center of the front striking face. Additionally, rail portions 
preferably have a width in plan view not substantially greater than 
one-half inch and the recessed cavity has a depth of at least one-eighth 
and preferably at least one-quarter inch. By properly arranging and 
designing the recessed cavity, a significant improvement in the weight 
distribution and a resulting improvement in club effectiveness results. 
Additionally, the balance of the club head can be significantly improved. 
As can be seen from the foregoing, a primary object of the invention is the 
provision of a club head wherein the weight of the club is moved toward 
the heel and toe areas and the center of gravity of the head is in an 
elevated position on an axis extending through the middle of the sole and 
in alignment with the striking face of the club. 
A still further object of the invention is the provision of a club head of 
the type described which can be formed by conventional investment casting 
techniques from any of a variety of suitable metals. 
A still further object of the invention is the provision of a club head of 
the general type described wherein an improved club head balance results 
from the use of a recessed sole and peripheral rail members between the 
center of percussion and the heel and toe areas with the peripheral rail 
members joined integrally with a rail extending parallel to and adjacent 
the striking face to provide increased club head mass immediately adjacent 
the center of percussion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring more particularly to FIGS. 1 through 6, the club head of the 
subject invention is identified generally with the reference numeral 10 
and comprises a hollow metal body formed by conventional investment 
casting techniques from a cobalt-steel alloy identified as F-75 Cobalt. It 
should be appreciated, however, that many different metals or alloys could 
be used for forming the head of the invention and, additionally, many 
different known conventional forming techniques could be used. The club 
head as illustrated in the drawings is shown in a preferred form and the 
drawings illustrate the club head in actual, full size depiction. As is 
customary, the head includes a striking face indicated generally with the 
reference numeral 12 and inclined rearwardly as best seen in FIG. 5. The 
striking face 12 is preferably provided with suitable closely spaced 
grooves 14 which are cast or machined in the face in the arrangement 
shown. Here, again, however, many different types of grooves or surface 
treatments could be used to improve the engagement between the striking 
face and the ball. 
The striking face 12 extends between an upper wall 16 and a bottom wall 18. 
The upper wall 16 is preferably gently contoured as illustrated and 
connects integrally with a rear wall 20. The rear wall 20 is curved as 
shown and connects with the front wall or striking face 12 through a heel 
area 22 and a toe area 24. 
In the heel area, the hosel is formed as an integral portion of the body 
and extends upwardly at the predetermined angle illustrated. This angle 
can, of course, vary depending upon the club head lie desired and other 
factors necessary to suit the individual user's desires. 
It should be noted that both the heel and the toe areas of the club are 
somewhat concave in shape as shown at 28 and 30, respectively, in FIG. 4, 
for example. 
The sole area of the club is defined by the bottom wall 18. In this regard, 
the design of bottom wall be is such as to produce the previously 
described improved weighting and weight distribution in the club head. As 
illustrated, the bottom wall 18 is provided with an inwardly extending 
recess 36 which has a width W between the heel and toe areas and a length 
L extending generally in a direction perpendicular to the striking face 
12. Because of the recess 36 extending inwardly of the bottom wall 18 in 
the manner shown, there results a ground engaging sole area comprised of a 
front rail portion 38 and side rail portions 40 and 42, respectively (see 
FIG. 3). Side rail portion 40 is adjacent the toe portion of the head and 
extends generally perpendicular rearwardly from the striking face 12. The 
rail portion 42 is also an integral continuation of the front rail portion 
38 and runs adjacent the heel 22 of the head 10. Preferably, each of the 
rail portions 38, 40, and 42 have a width which is at least about one-half 
inch in width and has a height relative to the bottom of the recess in the 
range of from one-quarter to one-half inch. 
The general configuration for the recess 36 is shown in FIG. 5 and, in the 
preferred embodiment, extends from a depth of approximately three hundred 
thousandths of an inch adjacent the front rail portion 38 to a maximum 
depth of approximately four hundred thousandths of an inch adjacent the 
rear of the side rails 40, 42. To further increase the distribution of the 
weight in an upward direction, the club head is provided with the concave 
toe and heel portions 20, 30 previously mentioned as well as the recess 46 
which is shown at the lower portion of the rear wall 20 and best 
illustrated in FIGS. 5 and 6. This arrangement thus far described shifts 
the weight of the club head from the traditional spot in the center of the 
club to a location outwardly in the area of the outer side rail portions. 
In the club head illustrated, the side rail portions are spaced apart a 
distance of approximately one and one-quarter inches, and they have a 
length of approximately one and one-half inches. 
As mentioned earlier, the preferred embodiment of the club head of the 
subject invention is formed using conventional investment casting 
techniques. When manufactured from the previously mentioned F-75 Cobalt 
alloy, the head as shown in the drawings has a weight of approximately 200 
to 215 grams. In addition, the head is formed to be a hollow shell with 
the striking face having a thickness in the range of 0.125 to 0.136 inches 
and the sole plate area including the side rails being of about 0.040 to 
0.050 inches in thickness. The remaining portions of the head are about 
0.025 to 0.035 inches in thickness. 
FIGS. 7-12 illustrate an alternative form of club head formed in accordance 
with the invention. The club head of this embodiment is identified 
generally with reference numeral 100 and comprises a hollow metal body 
formed by conventional investment casting techniques from a stainless 
steel alloy identified as 17-4. It should be appreciated, however, that 
many different metals or alloys could be used for forming the head of the 
invention and, additionally, many different known conventional forming 
techniques could be used. Also, it should be noted that the club head 
illustrated in FIGS. 7-12 is shown in approximately actual, full-size 
depiction. 
As is customary, the head 100 includes a striking face indicated generally 
with the reference numeral 112 which is canted rearwardly as best seen in 
FIG. 12. Striking face 112 is preferably provided with suitable closely 
spaced grooves 114 which are cast or machined into the face in an 
effective arrangement. Here again, however, many different types of 
grooves or surface treatments could be used to improve the engagement of 
the striking face with the ball. Vertical score lines 115 generally define 
a preferred impact region (center of percussion) of the striking face 
wherein ball impact achieves optimum distance and control. 
The striking face 112 extends between an upper wall 116 and a bottom wall 
118. The upper wall 116 is preferably gently contoured as illustrated and 
connects integrally with a rear wall 120. The rear wall 120 is curved as 
shown and connects with the front wall or striking face 112 via a heel 
area 122 and a toe area 124. 
In heel area 122, a hosel 125 is formed as an integral portion of the body 
and extends upwardly at a predetermined angle. This angle can, of course, 
vary depending on the club head lie desired and other factors necessary to 
suit the individual user's requirements. 
The sole area of the club is defined by the bottom wall 118. In this 
regard, the design of bottom wall 118 is such as to produce the previously 
described improved weighting and weight distribution of the club. 
Particularly, the weighted members are positioned to increase the amount 
of mass in the club head adjacent the optimum striking area on the club 
face improving the energy impact of off-center hits without significantly 
reducing the energy/mass available for well struck balls as is the case 
with traditional perimeter weighting. In addition, the invention's 
weighting system results in an elevation of the center of gravity. 
As illustrated, the bottom wall 118 is provided with a first inwardly 
extending recess 136 which has a width W' defined by side rail members 140 
and 142. The first recess 136 has a length L' extending generally in a 
direction perpendicular to the striking face 112. In addition, a second 
recess in the form of a toe recess 137 is defined by the side rail member 
140 and front rail 138 and extends to toe area 124. A third recess shown 
as a heel recess 139 is defined by side rail member 142 and front rail 138 
and extends to heel area 122. Because the three recesses 136, 137 and 139 
extend inwardly to the bottom wall 118 in the manner shown, the club head 
100 has a ground engaging sole area comprised of front rail portion 138 
and side rail portions 140 and 142. Side rail portions 140 and 142 extend 
generally perpendicular and rearwardly from the striking face 112. Side 
rail portions 140 and 142 are preferably integral continuations of the 
front rail portion 138 creating a generally rectangular cavity 136. 
Preferably, each of the rail portions 138, 140 and 142 have a width which 
is at least about one-quarter to one-half inch in width and a height 
relative to the bottom of the recess in the range of from one-sixteenth to 
one-quarter inch. Depending upon the width of rail portions 138, 140 and 
142, the length L' will be in the range of about 21/8 to 21/2 inches and 
the width W' will be in the range of about 5/8 to 11/16 inches. 
Particularly, a #1 wood may have a length L' of 21/2" and a width W' of 
11/16"; a #3 wood a length L' of 25/16" and a width W' of 1"; a #5 wood a 
length L' of 22/8" and a width W' of 6/8"; and a #7 wood a length L' of 
21/8" and a width W' of 5/8". Additionally, the front rail portion extends 
beyond the side rails a distance of about 11/32". 
In contrast to the newly developed perimeter weighting systems which 
disperse weight to edges of the club, while decreasing mass at the center 
of percussion, this arrangement shifts weight in the club head from the 
traditional spot in the center in the club head to a location surrounding 
the center of the club increasing the mass adjacent the center of 
percussion where most off-center hits occur. Accordingly, the club head 
maintains mass in the area which impacts well-struck balls, provides a 
larger effective impact area and greater energy is transferred to the golf 
ball. 
As seen in FIG. 10, bottom wall 118 has a generally arcuate shape from heel 
area 122 to toe portion 124. The arcuate shape of bottom wall 118 in 
conjunction with the arcuate shape of upper wall 116 from heel to toe 
creates a golf club head with its thickest portion occurring at the 
approximate center of the club head. 
When manufactured from the previously mentioned stainless steel alloy, the 
head as shown in the drawings L as a weight of approximately 204 to 218 
grams. Preferably, a #1 wood weighs about 204 grams; a #3 wood 210 grams; 
and a #5 or #7 wood 218 grams. 
Preferably, the head is formed to be a hollow shell with a striking face 
having a thickness in the range of about 2.8 to 3.2 mm. 
Particularly, a #1 wood face is about 2.8 mm thick; a #3 wood face is about 
3.0 mm thick; a #5 wood face is about 3.3 mm thick; and a #7 wood face is 
about 3.2 mm thick. Bottom wall 118 has an average thickness, excluding 
the side rails of about 1.4 to 1.8 inches, wherein the heel area is 
generally thicker. Specifically, the sole plate of a #1 wood is preferably 
about 1.8 mm in the heel area and 1.3 mm in the toe; a #3 wood 1.8 mm in 
the heel and 1.5 mm in the toe; a #5 wood 1.7 mm in the heel and 1.2 in 
the toe; and a #7 wood 2.0 mm in the heel and 1.6 in the toe. The 
remaining portions of the club head are between about 1.0 mm to 1.5 mm 
inches in thickness. 
The invention has been described with reference to the preferred 
embodiments. Obviously, modifications and alterations will occur to others 
upon a reading and understanding of this specification. It is intended to 
include all such modifications and alterations insofar as they come within 
the scope of the appended claims or the equivalents thereof.